UNITED STATES DEPARTMENT OF COMMERCE

BUREAU OF STANDARDS

THERMAL PROPERTIES OF

PETROLEUM PRODUCTS

MISCELLANEOUS PUBLICATION OF THE BUREAU OF STANDARDS, No. 97

UNITED STATES DEPARTMENT OF COMMERCE

R. P. LAMONT, Secretary BUREAU OF STANDARDS

GEORGE K. BURGESS, Director

MISCELLANEOUS PUBLICATION No. 97 THERMAL PROPERTIES OF

PETROLEUM PRODUCTS

NOVEMBER 9, 1929

UNITED STATES

GOVERNMENT PRINTING OFFICE

WASHINGTON : 1929

F<ir isale by tfttf^uperintendent of Dotmrtients, Washington, D. C. - - - Price IS cants

THERMAL PROPERTIES OF PETROLEUM PRODUCTS

By C. S. Cragoe

ABSTRACT

Various thermal properties of petroleum products are given in numerous tables which embody

the results of a critical study of the data in the literature, together with unpublished data obtained

at the Bureau of Standards. The tables contain what appear to be the most reliable values at

present available. The experimental basis for each table, and the agreement of the tabulated values

with experimental results, are given. Accompanying each table is a statement regarding the esti- mated accuracy of the data and a practical example of the use of the data. The tables have been

prepared in forms convenient for use in engineering.

CONTENTS

Page

I. Introduction 1

II. Fundamental units and constants 2

III. Thermal expansion t 4

1. Thermal expansion of petroleum asphalts and fluxes 6

2. Thermal expansion of volatile petroleum liquids 8

3. Thermal expansion of gasoline-benzol mixtures 10

IV. Heats of combustion : 14

1. Heats of combustion of crude oils, fuel oils, and kerosenes 16

2. Heats of combustion of volatile petroleum products 18

3. Heats of combustion of gasoline-benzol mixtures 20

V. Specific volume of vapor 22

VI. Thermal conductivity 24

VII. Specific heat - 26

1. Specific heat of petroleum oils of various gravities in Btu./lb. °F. or cal./g °C__ 28

2. Specific heat of petroleum vapors 28

3. Specific heat of petroleum oils of various gravities in Btu./gal. °F 30

4. Specific heat of petroleum asphalt 30

VIII. Latent heat of vaporization 32 IX. Heat content 36

1. Heat content of petroleum liquids 36

2. Heat content of petroleum vapors 37

3. Heat content of asphalt 42

4. Heat content of paraffin wax 44

X. Conclusion 46

I. INTRODUCTION

The Bureau of Standards receives many requests for information on the thermal

properties of petroleum products from other departments of the Government, from

the petroleum industry, and from users of these products which have found so wide a

variety of applications. Information of this sort is rarely to be found in systematic

form such that appropriate values for a desired property may readily be assigned to

the particular product in question. Engineering handbooks and physical and

chemical tables, the more accessable sources of such information, are surprisingly

1
2 BUREAU OF STANDARDS

deficient in this respect and the values given in these publications differ widely in j many instances.

The Bureau of Standards has made no extensive experimental study of the I subject as a whole, but has had occasion during the past few years to make numerous

determinations of some of the thermal properties of petroleum products in combination

with other investigations carried out in the laboratories of the Government. In 1927 an investigation was undertaken on the thermodynamic properties of petroleum

hydrocarbons, listed as project No. 38 of American Petroleum Institute Research,

j In order to lay out an experimental program intelligently, it was necessary to make a

critical study of the data avaiJable on the subject in the literature. The results obtained from this critical study when combined with unpublished results obtained at the bureau, including some preliminary results obtained under project No. 38,

appeared of sufficient technical importance to warrant the preparation of preliminary

tables covering several of the properties which have been investigated experimentally.

Because of the lack of published information in a form readily usable by the industry,

tables have been prepared in engineering units.

Most petroleum products consist essentially of a large number of different hydrocarbons which are so nearly alike physically that a mixture of them exhibits a thermodynamic behavior somewhat analogous to that shown by a mixture of isotopes.

Experimental evidence indicates that many of the thermodynamic properties of mixtures of hydrocarbons are not seriously affected by considerable changes in

composition. In fact, it has been found that many of these properties are very

closely related to the density of the liquid which is usually known or can be readily

determined with a hydrometer. This relationship afforded a very useful means of correlating existing data on commercial products. By the same means a valuable

check was obtained from data on pure hydrocarbons known to exist as constituent

parts of these products. Although some consistent differences were found between

data on paraffin and naphthene base products of the same density, these differences were small and, consequently, of little significance in practical applications of the

data. It must be realized, however, that values for the properties of petroleum

products, which are subject to considerable variation in composition, can not be

assigned with the same degree of accuracy as can be done in the case of materials

which have a definite composition.

H. FUNDAMENTAL UNITS AND CONSTANTS

Temperature scale.—The Fahrenheit scale as used in this paper is derived from

the International centigrade scale by means of the relation

Fahrenheit temperature = (1.8 X centigrade temperature) + 32

The International centigrade scale adopted by the International Conference of ; Weights and Measures at Paris in 1927 is realized in the temperature interval 0° to 660° C, by means of the resistance thermometer of pure platinum, standardized

at the temperatures of melting ice (0° C), condensing steam (100° C), and condensing

sulphur vapor (444.6° C), all at standard atmospheric pressure. In accordance with common practice in the United States, 60° F. is used here

as the reference temperature for specifying the density and volume of petroleum

products.
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 6

Mass.—The fundamental unit of mass, the kilogram, is used indirectly here. All units of weight used in this paper are weights in vacuo (mass) and not apparent

weights in air. The difference is small in all cases involved here, amounting to 0.1 or 0.2 per cent. Since most of the experimental data considered were given in terms

of unit mass, these units were retained and used consistently throughout. The

Hunts used are related as follows

:

1 pound = 0.453592 kilograms

Volume.—The fundamental unit of liquid volume, the liter, is defined as the

volume occupied by 1 kilogram of pure water at its maximum density (4° C). The

unit of liquid volume actually used throughout this circular, however, is the gallon

(231 cubic inches) because of the general use of this unit in engineering and industrial

practice in the United States. This unit is defined in terms of the fundamental unit

by the relation

1 gallon = 3.78533 liters It is often convenient to determine the volume of liquid containers by weighing

them both empty and filled with water. Since the mass of a gallon of pure water at 60° F. is known, the unit of liquid volume used here may be realized directly from

the fundamental unit of mass, by the relation.

1 gallon = 3.78170 kilograms or 8.33722 pounds of water at 60° F.

Density.—Mass per unit volume is the universal definition of density. In this

circular, densities are expressed in pounds per gallon which are related to the fundamental units by

1 pound per gallon = 0.119829 kilograms per liter Densities are also expressed in terms of specific gravity, defined by

i 60° TM density of oil at 60° F.

Specific gravity at w F>=

density of water at 6Qo R

which is equivalent to the following numerical relation

Density of oil at 60° F. in lbs. per gal. = 8.33722 X specific gravity of oil at 60°/60° F. Densities are commonly determined by means of a hydrometer, an instrument

familiar to large numbers of persons who take an interest in their storage batteries.

Some hydrometers are graduated to indicate density or specific gravity directly,

although there are almost an infinite variety of arbitrary hydrometer scales in

existence. Each industry in which hydrometers are used appears to have its own

selection of arbitrary scales. The petroleum industry has had, in the past, two such

arbitrary scales, both of which were known as Baume scales for liquids lighter than

water. In order to avoid confusion, the American Petroleum Institute, the Bureau

of Mines, and the Bureau of Standards agreed, in 1921, to recommend that in the

future only one arbitrary scale be used in the petroleum industry, and that it be

known as the A. P. I. scale. This scale is defined by the relation

Degrees A. P. i.-g—J*^^ -131.5

The A. P. I. scale is used extensively in the classification and description of petroleum

products. In order to make the data contained in this circular of convenience to those unfamiliar with this scale, it appeared desirable to use both, degrees A. P. I.
4 BUREAU OF STA.ND A.RDS and its equivalent, specific gravity at 60°/60° F. Degrees A. P. I. are used as one

of the independent variables in the tabulation of the data partly because they are equivalent to a uniform scale of specific volume.

Heat unit.—The fundamental heat unit used here is the international joule, or watt second, since electric heating was employed in most of the calorimetric measure- , ments considered. The relation between this unit and the corresponding cgs unit,

as given in Bureau of Standards Circular No. 60, 2d ed. (1920) is 1 international joule = 1.00034 absolute joules j The difference between these units is of little importance here.

As secondary beat units the calorie and the British thermal unit (Btu.) have

been used. The calorie is defined for the purposes of this circular as 4.183 absolute

joules. According to present evidence, this corresponds approximately to the 15°

calorie. The Btu. as here used is derived from the calorie by means of the relation

between the centigrade and Fahrenheit degrees and the relation between the kilo- gram and the pound. Thus

1 Btu. =|x 453.592 = 252.00 calories = 1054.1 absolute joules

This method of defining the Btu. retains the convenient relation

1 calorie per gram = 1.8 Btu. per pound

III. THERMAL EXPANSION

The results of measurements of thermal expansion made in 1912-1915 on 87

petroleum oils, ranging in density from 0.62 to 0.96 (16° to 97° A. P. I.) are recorded

in Bureau of Standards Technologic Paper No. 77, Density and Thermal Expansion

of American Petroleum Oils, by H. W. Bearce and E. L. Peffer. These measure- ments form the basis for the extensive tables given in Bureau of Standards Circular

No. 154, National Standard Petroleum Oil Tables, also the abridged tables given in the supplement to Circular No. 154, Abridged Volume Correction Table for Petro- leum Oils, which are sold only by the Superintendent of Documents, Government

Printing Office, Washington, D. C, at 30 cents and 5 cents, respectively.

The investigation on thermal expansion, made in 1912-1915, did not include the

following groups of commercial products:

(a) Petroleum asphalts and fluxes,

(b) volatile petroleum liquids (specific gravity 0.50 to 0.62),

(c) mixtures of gasoline and benzol, and

(d) gasolines obtained from various cracking processes. Consequently, the data in Circular No. 154 do not extend to products (a) and (b). The data given in Circular No. 154 for gasolines are based upon expansion measure- ments made on " straight-run" gasolines and, therefore, are not applicable with the same accuracy to products (c) and (d). In order to supply approximate expansion

data on products (a) and (b) and also to indicate the order of magnitude of departures

of expansion data on products (c) and (d) from the data given in Circular No. 154,

Tables 1 to 5, inclusive, have been compiled.

6 BUREAU OF STANDARDS

1. THERMAL EXPANSION OF PETROLEUM ASPHALTS AND FLUXES

Values of F60/Ft given in Table 1 represent volumes at 60° F. occupied by a unit

volume at indicated temperatures, t° F. For example, 1 gallon of petroleum asphalt

measured at 350° F. will have a volume of 0.9031 gallon at 60° F. Table 1 is similar in

form to the corresponding table given in National Standard Petroleum Oil Tables, B. S. Circular No. 154, and to the abridged volume correction table given in the

supplement to Circular No. 154. In fact, Table 1 might well be considered as an

addition to that supplement; that is, as group O for the gravity range 0° to 15°

A. P. I. The data given in Table 1 were calculated from the equation,

Vt =Vm [1+A (t-e>0) + B (#-60) 2

] using A = 0.000341 and 5 = 0.0000001, which is equivalent to the following:

Temperature range in °JP. Mean coefficient of expansion 60 to 150 0. 00035

60 to 250 . 00036

60 to 350 . 00037

60 to 450 . 00038

These are average values based on unpublished measurements made at the

Bureau of Standards on 25 samples within the temperature range 32° to 176° F., and

two samples within the range 60° to 400° F. These coefficients and the expansions,

(Veo/Vt) — 1, obtained from Table 1 apply to petroleum asphalts and fluxes in general

with an estimated accuracy of 5 per cent, which is equivalent to the following per- centage accuracy in the relative volumes, F60 /F«, for various temperature ranges:

0.1 per cent, 0° to 100°; 0.2 per cent, 100° to 200°; 0.4 per cent, 200° to 300°; 0.6 per

cent, 300° to 400°; and 0.8 per cent, 400° to 500° F. Products containing wax, gas bubbles, or nonbituminous materials have expansions which differ from those given by Table 1 in proportion to the amount present.

The experimental data obtained by:

Observer Material Reference

Zeitfuchs ... . California asphalt Ind. Eng. Chem., 17, p. 1280; 1925. Rossbaeher.. Petroleum residuums - Ind. Eng. Chem., 7, p. 577; 1915.

agree with the expansions (V&Q/Vt ) — 1 given by Table 1 to about 5 per cent. These

constitute the only data found in the literature on this class of petroleum products.

Example.—If the volume of a given quantity of petroleum asphalt is 10,000 gallons at 350° F., what is its volume at 60° F.? Calculate from the value given in Table 1 as follows: 760 = 10,OOOX0.9031 = 9031 gallons at 60° F.
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 7

Table 1.Thermal expansion of petroleum asphalts and fluxes

Temp.

t°F. Vt Temp.

t°F. Vto Vt Temp.t°F. Fao Vt Temp.

t°F. Vt Temp.

t°F. Vto Vt

1. 0205 100 0. 9864 200 0. 9527 300 0. 9195 400 "0. 8869

2 1. 0198 102 . 9857 202 . 9520 302 . 9188 402 .8863

1 1 Ol Q1 l. uxyx 1XU1C\A . yoou 9AA ZU1 . yoxo OU1 304 Q1 81 . yiox 404 88FiA . 00OO

a 1 ni 1. UX60 1 nA XUO . Q8A4 yoii ZUO . youo ouo . Q1y x 7K/ 4HA 1UO . 00OU

QO

11. niUl/o7e iXUona . Q837 yoo / 9A8 ZUo . youu OUo 308 . Q1yxooA8 408 . 00IO 8843

10 1. 0171 110 . 9830 210 . 9493 310 . 9162 410 .8837

12 1. 0164 112 . 9823 212 . 9486 312 . 9155 412 . 8831

1 AXI 1 m £7 1. UXO/ 1XXI1 A Q81 A . yoxo 01ZX1A QAan . yiou 314 . Q1yx^ty AQ 411X14 . oozi aa94

1IDA 1 ni ^n 1. UlOU 1XXO1 A . Qsi ysxun 91ZIOA . Q473 yi/ o OXO 31 A Q1 49 411XOA . 881 00X08

1 8 11. fi1 UXIOAQ 118 XXo . youo OlZXo8 OAAA . y^too OXo 31 a qi 3f;

. yxoo 411x0a 881 1

. 00 XX 30 1. 0137 120 . 9796 220 . 9460 320 . 9129 420 . 8805

22 1. 0130 122 . 9789 222 . 9453 322 . 9122 422 . 8799

Z1 i ni 93 1XZ194 . Q783 y / oo 99/1 ZZ1 Q44A OZ1- 394 . Q1y x

1xoA 494 izi .08709 / yz

9AZO 1. UXIO 1XZO9A . Q77A y / / o 99A ZZO OZO 39A . qiyiuyno 49A 1ZO . o/OO 878A

98 il. niuxuyno 1XZo98 . Q7AQ y / oy 998 ZZo Q433 OZO 398 . Q1yxuo03 49IZoa . 877Q oi /y 30 1. 0102 130 . 9762 230 . 9426 330 . 9096 430 . 8773

32 1. 0095 132 . 9755 232 . 9420 332 . 9090 432 .8767

oi34 1 0080 1XOl34. . Q74Q y / iy 934. Q41 3 334 004t . 0083 yuoo 434 101 . 87A0 O / ou

3fi 1. UUoZ 1XOO3A . Q749 y < iz 93A ZOO . yiuo OOO 33A . Q077 yu/ / 43A IOO . 87^4 0/ 01 oo38 1 007^ 1XOo38 . 073^ y i oo 938 Zoo . Q400 y'l-uu OOo 338 . 0070 yu / u 438 rkOO .0/1/ 8747

40 1. 0068 140 . 9728 240 . 9393 340 . 9064 440 . 8741

42 1. 0061 142 . 9722 242 . 9386 342 . 9057 442 . 8735

4411 X. UUOI 1XIILA Q71 K . y/ xo 9AA . Q38H yoou oft 344 . yuox 444 . 0/8798Zo

4fi ID i1. 004.8 UUlo 1XIO4fi . Q708 y / uo 9AA zio . 0373 yo i o oto 34A 0044 44A no . 8799 / zz 48 11. 0041 UU1X 1Xlo4.8 . Q701 y/ux 9Aa ZIo . Q3A7 yoo/ O'lo 348 . QH38 yuoo 448 llo 871 A . 0/ XO 50 1. 0034 150 . 9695 250 . 9360 350 . 9031 450 . 8709

52 1. 0027 152 . 9688 252 . 9353 352 . 9025 452 . 8703

OI^4 1 0090 1XOl^4 . QA81 yoox 9^4 Z01 Q347 OO3^41! . QOI yuxo8 4^4 101 . ooy/ 8AQ7

OO 1X. 001 UUX14 1XOO^A . QA74 yo 1 i 9£A ZOO . yo'i-u 3CiA OOO QH1 9 . yuxz 4p;a 100 . ooyu

^8 iX. 0007 uuu / 1XOO^8 . yooo 9^8 ZOO . Q333 yooo 3^8 OOo . QOO^ yuuo 4^8 lOo . oool 8Aa4

60 1. 0000 160 . 9661 260 . 9327 360 . 8999 460 .8678

62 . 9993 162 . 9654 262 . 9320 362 . 8992 462 .8671

A4 . QQ8A yyoo 1XOlA4 . QAA7 yoi/ 9AA ZOI Q31 3 . yoio OO'i 3AA . oyoo 8Q8A 4A4 IOI 8AAt^ . oOOO

Aft DO 008O 1XOOAA . QA41 yoix OAA ZOO . you/ QAA OOO 8Q7Q . oy/y AAA 100 . oooy

DoA8 . 0073 yy / o 1XOOA8 QA34 9A8 ZOO . youu 3A8 005 . 8Q73 oy /o 4Aa lOo . oOOZ

70 . 9966 170 . 9627 270 . 9294 37.0 . 8966 470 . 8646

72 . 9959 172 . 9620 272 . 9287 372 . 8960 472 . 8640

74. . yyoz 1X 74/

1

. QA1 yoxiA 974 Z / 1 . yzou o/4t . oyoo A7A 1/1 . 0O00

7A/ O

1X 7A/O . OAA7 you/ 07A Z/O 007/1 . yz / 4t Q7« O /0 . oy^t/ /17A I/O . OOZ/

4 O . QQ3Q yyoy 1X 78/O . QAnn youu 078 Z/O QOA7 . yzo/ O/o . ©y^u zl78 1/5 . OOZX 80 . 9932 180 . 9594 280 . 9260 380 . 8934 480 . 8614

82 . 9925 182 . 9587 282 . 9254 382 . 8927 482 . 8608

84 . 9918 184 . 9580 284 . 9247 384 . 8921 484 . 8602

86 . 9912 186 . 9573 286 . 9241 386 . 8914 486 . 8595

88 . 9905 188 . 9567 288 . 9234 388 . 8908 488 . 8589

90 . 9898 190 . 9560 290 . 9228 390 . 8901 490 . 8583

92 . 9891 192 . 9553 292 . 9221 392 . 8895 492 .8577

94 . 9884 194 . 9547 294 . 9214 394 . 8888 494 . 8570

96 . 9878 196 . 9540 296 . 9208 398 . 8882 496 . 8564

98 .9871 198 . 9533 298 . 9201 398 . 8876 498 . 8558

100 . 9864 200 . 9527 300 . 9195 400 . 8869 500 . 8552

56161°—29 2
s BUREAU OF STANDARDS

2. THERMAL EXPANSION OF VOLATILE PETROLEUM LIQUIDS

The thermal expansion of a particular product; for example, liquefied petroleum

gas, may be estimated from Table 2 if any one of the following characteristics of the

product is known: Normal bubble point,1 vapor pressure,1 or density. The expansion coefficients, A and B, given in Table 2, are defined by the equation

Vt = F60 [1 + A(f - 60) + B(t ~ 60)2

] The estimated accuracy of expansions (Vt — V&0)/Vq , calculated from the tabulated

values of A and B, is 10 per cent for the temperature range 0° to 130° F. The values given in the last two columns of Table 2 represent the maximum

charge for each 1-pound water capacity of container at 60° F., which will not completely fill the container with liquid at 100° F. or 130° F. (See Interstate Commerce Commission Regulations, Pt. I, par. 562; Pt. II, par. 148.) The estimated

accuracy of these values is 5 per cent. The data in Table 2 were compiled from experimental data on propane, n- butane, iso-butane, n-pentane, and ^so-pentane published by Dana, Jenkins, Burdick and Timm, Refrigerating Eng., 12, p. 387; 1926; and by Sidney Young, Sci. Proc. Royal Dublin Soc, 12, p. 374; 1910, using mixture rules. Expansion data

given in International Critical Tables, Volume III, indicate that the above hydrocarbons of the paraffin series expand less rapidly than hydrocarbons of other series with corresponding densities and conversely that these paraffin series hydrocarbons

expand more rapidly than those of other series with corresponding vapor pressures

at a given temperature. Therefore, in cases involving safety, it is desirable that

values in the last two columns of Table 2 be chosen from determinations of vapor

pressure rather than density, since some commercial products are known to contain variable amounts of hydrocarbons other than the paraffin series. Exam-pie. 1 —What is the maximum weight of material having a vapor pressure of 100 lbs. /in.2 gauge at 70° F., which can be charged into a cylinder of 90 pounds water capacity at 60° F. which

will not completely ml the cylinder with liquid at 130° F.? Answer: 0.454X90=40.86 pounds.

Exam-pie 2.—What is the maximum weight of material, having a normal bubble point of 20° F., which can be charged into an insulated tank car of 8,000 pounds water capacity at 60° F. in order

to be free from hydrostatic pressure at 100° F.? Answer: 0.547X8,000 =4,376 pounds.

1 The vapor pressure of a many-component liquid, as used here, is defined as the equilibrium pressure on a two-phase system composed of a relatively large volume of liquid and such a small volume of vapor that any decrease in the vapor volume would

not alter the pressure appreciably. The temperature at which the vapor pressure, as denned above, is equal to one standard atmos- phere is designated the normal bubble point.
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 9

Table 2.

Thermal expansion of volatile petroleum liquids

Normal

bubble

point,

o Yt

Vapor pressure, lbs ./in. 2 gauge at— Approximate gravity,

at 60° F. Expansioncoefficients Pounds of fluid per pound water capacity, hydrostatic

pressure, at—

70° F. 90° F. 100° F. 130° F. Specific ° A. P. I. AX10« BX107 100° F. 130° F. -50

| -48

\ -46

-44

-42

126

121 116

111 107

171 165

159

153 147

197

190

183 176 170

291

281 272 263 254

0. 501

. 504

. 507

. 510

. 513

151. 5

149. 5

147. 5

146.

144. 5

170

167

164

161 158

98

9388

8378

0. 461

. 465

. 469

. 473

.477

0. 428

. 433

. 438

. 442 .447

-40

-38

-36

-34

-32

10399

95

9187

141 136

131 126

121

164

158

152 147

141

246

238 230

222 214

. 516

. 519

. 522

. 525

. 528

142. 5

141.

139. 5

138. 136. 5

1 155

152 150

147

145

74

7067

6360

. 481

. 485

.488

. 492

.495

. 451

. 455 .459

. 463 .467

-30

-28

-26

-24

-22

83

8076

7370

117

112

108 104

100

136

131 126

121 117

207

200

193

187 180

. 531

. 533

. 536

. 538 .540

135.

134. 132. 5

131. 5

130. 5

142

140

138

137

135

57

55

53

5149

.498

. 501

. 504

. 506

. 509

.471

. 474

. 478

. 481 .484

-20

-18

-16

-14

-12

67

64

615856

96

9288

84

81

112

108 104

10096

174

168

162 157

151

. 542

. 544

. 546

. 548

. 550

129. 5

128. 5

127. 5

126. 5

125. 5

134

132

131 129 128

47

4644

43

42

. 511

. 513

. 516

. 518

.520

.487

. 489

. 492

. 494

. 496

-10

-8

-6

-4

-2

53

514846

44

78

75

7168

66

92

8985

82

78

146

141 136

131 126

. 552

. 553

. 555

. 556

. 557

125.

124. 123. 5

123.

122. 5

127

126

125 124

124

4140

393837

. 522

. 523

. 525

. 526

. 528

. 498

. 500

. 502

. 503

. 505

2

4

6

8

4240

38

3634

6360

5755

52

75

72

69

6664

122 117

113

109 105

. 558

. 560

. 561

. 562

. 564

122.

121.

120. 5

120. 119. 5

123

122

121 120 119

37

36

3534

33

. 529

. 531

. 532

. 533

. 535

. 506

. 508

. 509

. 511

. 512

10

1214

16

18

3230

2927

26

50

48

46

43

41

6158

56

53

51

1019794

90

87

.565

. 567

. 568

. 570

. 572

119. 118.

117. 5

117.

116.

119

118

117

116 115

3332

31

3130

.536

. 538

. 540

. 542

. 544

. 514

. 516

. 518

. 520

. 522 20

22

2426

28

24

23

2120

19

39

37

3634

32

49

4644

42

40

84

80

77

74

72

. 574

. 576

. 578

. 580

. 582

115.

114.

113. 112. 5

111. 5

113

112

111 110 109

29

2827

26

26

. 547

. 549

.551

. 553

. 555

. 525

. 527

. 530

. 532

. 535

30

32

3436

38

17

16

1514

13

30

29

27

2624

3837

3533

31

6966

63

6158

. 584

. 586

. 588

. 590

. 592

111. 110.

109.

108. 107.

108

107

106

105 104

2524

24

23

22

.558

. 560

. 562

. 564

.567

. 537

. 540

. 542

. 544

.547

40

45

50

55

60

70

129

7

5

3

2320

17

14

117

30

26

22

19

16

11

56

5045

40

35

28

. 595

. 600

. 605

. 610

. 615

. 620

106. 104. 5

102. 5

100. 5

98. 5

96. 5

102

10098

96

94

92

2120

19

17

16

15

. 570

. 575

. 580

. 585

. 590

. 596

. 550

. 556

. 561

. 567

. 573

. 579
10 BUREAU OF STA.NDA.RDS

3. THERMAL EXPANSION OF GASOLINE-BENZOL MIXTURES 2 The values given in the columns marked per cent in Tables 3, 4, and 5 are equivalent to those given in Bureau of Standards Circular No. 154. These values

are based on expansion measurements made in 1912-1915 on " straight run" gasolines.

They are included here to facilitate comparisons and interpolations.

The values given in the columns marked 25 per cent and 50 per cent in Tables

3, 4, and 5 were calculated by means of mixture rules using average values for the

coefficients of expansion of motor benzol and the coefficients of expansion of "straight

run" gasolines used as a basis for Circular 154. Unpublished measurements made

recently at this bureau under research project No. 38 of the American Petroleum

Institute, have confirmed the mixture rules used for this purpose.

The values given in the column marked "motor benzol 100 per cent" are based on the following average values for the coefficients of expansion of motor benzol:

.4 = 0.00065 and 5= 0.0000005.

. The estimated accuracy of the values given in Tables 4 and 5 and of expansions,

(Vt — Vm)/Vt , obtained from Table 3, is 5 per cent for mixtures of benzol and "straight

run" gasolines. Thus the relative volumes, V60/Vt , given in Table 3, are probably

accurate to better than 0.1 per cent in the temperature range 30° to 90° F. and to better than 0.2 per cent outside this temperature range.

Example 1.—A tank car contains, at 20 °F., 10,000 gallons of a mixture of gasoline and 40 per

cent benzol whose gravity is 47.5° A. P. I. at 60° F. What is the volume of the mixture at 60° F.? The result may be obtained from Table 3 by "double interpolation" as follows: 760 = 10,000 [1.0258-^ (0.0029)+^- (0.0017)] = 10,255 gallons

Example 2.—At 90° F. the indication of a hydrometer in a mixture of gasoline and 50 per

cent benzol is (a) 54.5° A. P. I. or (6) 0.7609. What is the gravity of the mixture at 60° F.?

(a) Applying the correction given in Table 4 gives 54.5—3.9=50.6° A. P. I at 60° F.; or (&) applying the correction given in Table 5 gives 0.7609+0.0161 = 0.7770 at 60°/60° F.

4. THERMAL EXPANSION OF "CRACKED" GASOLINES2 The limited information available indicates that "nonblended" gasolines obtained

from liquid phase cracking processes have expansions approximately equivalent to mixtures of " straight run" gasoline and 10 per cent benzol, and those obtained from

vapor phase cracking processes have expansions approximately equivalent to mixtures

of " straight run" gasolines and 20 per cent benzol, for corresponding gravities in

each case.

2 The data given in Tables 3, 4, and 5, and the statement on cracked gasolines are based, in part, upon experimental results

to be presented in detail in a separate publication under project No, 38 of American Petroleum Institute Research,
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 11

Table 3.

Thermal expansion of gasoline-benzol mixtures

[Ratio of volume at 60° F. to volume at t° F., Vw/ Vt, for mixtures containing 0, 25, 50, and 100 per cent motor benzol, by volume]

Temp. t° F.

45° A. P. I. at 60° F.

Sp. gr. 0.8017 at 60°/60° F.

50° A. P. I. at 60° F.

Sp. gr. 0.7796 at 60°/60° F.

55° A. P. I. at 60° F.

Sp. gr. 0.7587 at 60°/60° F.

Percentage motor-benzol Motor benzol

100 per cent

25 50 25 50 25 50

o 1. 0301 1. 0342 —,

1. 0386 1. 0324 —-»—1. 0367 1. 0410 1. 0347 1. 0391 1. 0440 1. 0387

5 1. 0276 1 0314 1. 0354 1. 0297 1. 0337 1. 0376 1.0318 1.0359 1. 0404 1. 0355

10 1. 0251 1. 0286 1. 0322 1. 0270 1. 0307 1. 0343 1. 0290! 1. 0326 1 0368 1. 0323

15 1. 0226 1. 0257 . 1. 0290 i

. 0243 1. 0276 1. 0309 1. 0261 1. 0294 1. 0332 1. 0291

20 1. 0201 h 0229 1. 0258 1. 0216 1. 0246 1. 0275 1. 0232 1. 0261 1. 0295 1. 0259

22 1. 0191 1. 0217 1. 0245 1. 0205 1. 0233 1. 0261 1. 0220 1. 0248 1. 0280 1. 0246

24 1. 0181 1. 0206 1. 0232 1. 0194 1. 0221 1. 0248 1. 0209 1. 0235 1. 0266 1. 0233

26 1. 0171 1. 0194 1. 0219 1. 0184 1 0209 L 0234 1. 0197 1. 0222 1 0251 1. 0220

28 1. 0161 1. 0183 1. 0207 -< . 0173 1. 0197 1. 0220 1: 0186 1. 0209 1. 0237 1. 0207

30 1. 0151 1. 0171 1. 0194 1. 0162 1. 0184 L 0206 1. 0174[ 1.0196 1. 0222 1. 0194

32 1. 0141 1. 0160 1. 0181 1. 0151 1. 0172 1. 0193 1. 0162 L 0183 1. 0207 1. 0181 34 1. 0131 1. 0149 1. 0168 1 . 0140 1. 0160 1. 0179 1. 0151 1. 0170 1. 0192 1. 0168

36 1. 0121 1 0138 1. 0155 1 . 0130 1. 0148 L 0165 1. 0139 1. 0157 1. 0178 1. 0156

38 1. 0110 1. 0126 1. 0142 1 . 0119 1. 0135 1. 0151 1. 0128 1. 0144 l! 0163 1. 0143

40 1. 0100 1. 0115 1. 0129 1 . 0108 1. 0123 1. 0138 1. 0116 L 0131 1. 0148 1. 0130

42 1. 0090 1. O103 L 0116 1. 0097 1. 0111 L 0124 1. 0104! 1. 0118 1. 0133 1. 0117

44 1. 0080 1 0092 1. 0103 1. 0086 1. 0099 1. 0110 1. 0093 1. 0105 1. 0119 1. 0104

46 1. 0070 1. 0080 1. 0090 1. 0076 1 0086 1. 0096 1. 0081 1. 0092 1 0104 L 0091

48 1. 0060 1. 0069 1. 0078 1. 0065 1. 0074 h 0083 1. 0070 L 0079 1. 0089 1. 0078

50 1. 0050 1 0057 1. 0065 1. 0054 1. 0061 1. 0069 L 0058 1. 0066 1. 0074 1. 0065

52 1. 0040 1 0046 1. 0052 1. 0043 1. 0049 1. 0055 1. 00461 1. 0053 L 0059 1. 0052

54 1. 0030 1 0034 1. 0039 1. 0032 1. 0037 1. 0041 1.0035! 1.0039 1. 0044 1. 0039

56 1. 0020 1 0023 1. 0026 1. 0022 1. 0025 1. 0028 11 0023 1. 0026 1 0030 1. 0026

58 1. 0010 1 0011 1. 0013 1. 0011 1. 0012 1. 0014 h 0012 1. 0013 1. 0015 1. 0013

60 1. 0000 1 0000 1. 0000 1. 0000 1. 0000 1. 0000 h 0000 1. 0000 1. 0000 1. 0000

62 . 9990 9988 '. 9987 . 9989 ! 9987 '. 9986 . 9988 . 9987 '. 9985 . 9987

64 . 9980 9977 . 9974 . 9978 . 9975 . 9972 . 9977 . 9974 '. 9970 . 9974

66 . 9970 9965 '. 9961 i 9968 . 9963 '. 9958 . 9965 . 9960 '. 9955 . 9961 68 . 9960 9954 . 9948 . 9957 . 9951 . 9944 . 9954 .9947 ! 9940 '. 9948

70 . 9950 9942 . 9935 . 9946 . 9938 . 9930 . 9942 .9934 QQ25 . 9935 72 . 9940 9931 . 9922 . 9935 . 9926 . 9917 . 9930 . 9921 QQ1 1 . 9922

74 . 9929 9919 . 9909 9924 ; 9913 ] 9903 . 9919 . 9908 . 9896 9909

76 . 9919 9908 . 9896 9913 . 9901 . 9889 . 9907 . 9895 . aooi . VOUKJ 78 . 9909 9896 . 9883 9902 . 9888 . 9875 . 9896 . 9881 • iJOOO 80 . 9899 9885 . 9870 9891 . 9876 . 9861 . 9884 . 9868 . 9851 . 9870

82 . 9889 9873 . 9857 9880 . 9864 . 9847 . 9871 . 9855 . 9836 . 9857

84 . 9879 9862 . 9844 9869 . 9852 . 9833 . 9860 . 9842 . 9821 . 9844

86 . 9869 9850 . 9831 9859 . 9839 . 9819 . 9848 . 9828 . 9806 . 9830

88 . 9859 9839 . 98-18 9848 . 9827 . 9806 .9837 . 9815 . 9791 . 9817

90 . 9849 9827 . 9805 9837 . 9814 . 9792 . 9825 . 9802 .9776 . 9804

92 . 9839 9816 . 9792 9826 . 9802 . 9778 . 9813 . 9789 . 9761 . 9791 94 . 9829 9804 . 9779 9815 . 9789 . 9764 . 9802 . 9776 . 9746 . 9778

96 . 9819 9793 . 9765 9805 . 9777 . 9750 . 9790 . 9763 . 9731 . 9765

98 . 9809 9781 . 9753 9794 . 9764 . 9736 . 9779 . 9749 .9716 . 9752

100 . 9799 9770 . 9740 9783 . 9752 . 9722 . 9767 . 9736 . 9701 . 9739

105 . 9773 9741 . 9707 9756 . 9727 . 9687 . 9737 . 9703 . 9663 . 9706

110 . 9748 9712 . 9675 9729 . 9690 . 9652 . 9708 . 9670 . 9626 . 9673

115 . 9723 9684 . 9642 9702 . 9659 . 9617 . 9679 . 9637 . 9588 . 9640

120 . 9698 9655 . 9609 9674 . 9628 . 9582 . 9650 . 9604 . 9550 . 9607

125 . 9673 9626 . 9577 9647 . 9597 . 9547 . 9620 . 9571 . 9513 . 9574
12 BUREAU OF STANDARDS

Table 4.

Corrections to readings of hydrometers in gasoline-benzol mixtures to reduce to ° A. P. I.

at 60° F

[Mixtures containing 0, 25, and 50 per cent motor benzol, by volume]

45° A. P. I. observed 50° A. P. I. observed 55° A. P. I. observed

Obs. Temp Percentage motor benzol Obs. Temp.

°F.

' °F. 25

1 50

! 25 50 25 50

Add to observed ° A. P. I.

5. 7 6. 5 7. 5 O. O 7. 2 8. 4 6. 9 .7. 9 9. 3

r

5. 1 5. 9 6. 8 5. 7 6. 5 7. 6 6. 3 7. 2 8. 4

r 1U 4. 6 5. 3 6. 1 5. 2 5. 9 6. 8 O. 4 6. 5 7. 5 1U

10 4. 1 4. 8 5. 4 4 6 5. 3 6. 1 O. 1 5. 8 6. 7 10 onZU 3.7 4. 2 4. 8 4 1 4 6 5.3 ^t. O 5. 1 5. 9 onZU

25 3. 2 3. 7 4. 2 3.5 4 46 Q Q o. y 4 4 5. 1 25 OA

2. 7 3. 1 3. 5 3. 3. 4 3. 9 3. 3 3. 8 4 4

OAoU

o2 2. 5 2. 9 3. 3 2. 8 3. 2 3. 7 3. 1 3. 5 4 1 oooz

OA 2. 3 2. 7 3.0 2.6 3. 3. 4 2. 8 3. 2 3. 8O/t oo 2. 2 2. 5 2. 8 2. 4 2. 7 3. 1 2. 6 3. 3. 5 OA 38 2.0 2.3 2.6 2.2 2.5 2.9 2. 4 2.7 3. 2 38 40 1. 8 2. 2.3 2.0 2. 3 2. 6 2. 2 2. 5 2. 9 40

42 1. 6 1. 8 2. 1 1.8 2. 2. 3 1. 9 2. 2 2. 6 42 44 1 4 1. 6 1.8 1.6 1. 8 2. 1 1. 7 2. 2. 3 44

46 1. 2 ll 4 1.6 1.4 1. 6 1. 8 1. 5 1. 7 2. 46

48 l! 1 L 2 1. 4 1. 2 1. 3 1.5 L 3 1. 5 1. 7 48

50 .9 1.0 1. 1 1.0 1. 1 1.3 1. 1 1.2 1.4 50

52 .7 .8 . 9 .8 . 9 1.0 . 9 1. 1. 1 52

KA04 .5 . 6 .7 . 6 .7 . 8 . 6 . 7 . 8 ot^4. 56 .4 . 4 . 5 . 4 . 4 . 5 . 4 . 5 . 6 56

58 . 2 . 2 . 2 . 2 . 2 . 3 . 2 . 2 . 3 58

Subtract from observed A. P. I.

60 0. 0. 0. 0. 0. 0.0 0. 0.0 0. ©0

62 . 2 . 2 . 2 . 2 . 2 . 2 . 2 . 2 .3 AOOZ 64 . 4 . 4 .4 . 4 .4 .5 .4 . 5 . 5

dA64

(JO DO . 5 .6 .7 . 6 .7 .7 .6 . 7 . 8 66

68 .7 .8 .9 .8 .9 1.0 .8 . 9 1. 1 68

70 .9 1.0 1. 1 1.0 1. 1 1. 2 1.0 1.2 1.3 MA70 72 1.0 1. 2 1.3 1. 1 1. 3 1.4 1. 2 1. 4 1. 6 72 74 1. 2 1.4 1. 5 1.3 1. 5 1.7 1.4 1. 6 1. 9 74

7b 1.4 1. 6 1.7 1.5 1. 7 1.9 1. 6 1. 9 2. 1 76

78 1.5 1. 7 2.0 1.7 1. 9 2.2 1. 8 2. 1 2. 4 78

80 1.7 1. 9 2. 2 1. 9 2. 1 2. 4 2.0 2.3 2.6 QA80

82 O 1 Z. 1 2. 4 2. 2.3 2. 7 2. 2 2 5 2 9 82 84 2. 2.3 2. 6 2. 2 2. 5 2. 9 2. 4 2. 8 3. 1 OA84 86 2. 2 2. 5 2. 8 2. 4 2.7 3. 1 2. 6 3. 3.4 86

88 2.4 2.7 3.0 2.6 2.9 3.3 2.8 3.2 3.6 88 90 2. 5 2.9 3. 2 2. 8 3. 1 3. 6 3.0 3.4 3.9 90

92 2. 7 3. 3. 4 2. 9 3. 3 3. 8 3. 2 3. 7 4 1 92 94 2. 8 3. 2 3. 6 3. 1 3. 5 4 3. 4 3.9 4 4 94

96 3. 3. 4 3. 8 3. 3 3. 7 4 2 3. 6 4 1 46 96 98 3. 1 3.6 40 3.4 3. 9 44 3.8 43 49 98

100 3.3 3.8 4 2 3.6 4 1 47 40 45 5. 1 100

105 3. 7 4. 2 4 7 40 4 6 5. 2 45 5.0 5.7 105

110 4. 1 4. 6 5. 2 4 5 5. 1 5.7 49 5. 6 6.3 110

115 4. 5 5. 1 5. 7 4 9 5.6 6. 3 5.4 6. 1 6.9 115

120 4.8 5. 5 6. 2 5.3 6. 6. 8 5. 8 6. 6 7. 4 120
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 13

Table 5.

Corrections to readings of hydrometers in gasoline-benzol mixtures to reduce to specific gravity at 60° /60° F.

[Mixtures containing 0, 25, and 50 per cent motor benzol, by volume]

Obs. Sp. gr.= 0.760 Obs. Sp. gr.== 0.780 Obs Sp. gr. = 0.800

Obs. Temp. F

Percentage motor benzol Obs. Temp,

o -p.

25 50 25 50 25 50

Subtract from observed specific gravity

5

101520

25

O 0979

. 0248

. 0224

. 0201

. 0177

. 0155

O 0307

. 0280

. 0253

. 0227

. 0201

. 0175

o o^ro

. 0328

. 0296

. 0265

. 0234

. 0204

. 0239

.0215

.0193

. 0171

. 0149

OU. 09Qrt \J6\3\J

. 0270

. 0245

. 0219

. 0194

. 0169

O 034.9

. 0311

. 0281

. 0251

. 0222

. 0193

0. 0251

. 0228

.0207

. 0184

.0164

. 0142

O 098^

. 0260

. 0235

. 0210

. 0186

. 0162

. 0296

. 0268

. 0240

. 0212

. 0185

510

1520

25 3032

34

3638

. 0132

. 0123

. 0114

. 0105

. 0096

. 0150

. 0140

. 0129

. 0119

. 0109

. 0174

. 0162

. 0150

. 0138

. 0126

. 0127

. 0118

. 0110

. 0101

. 0093

. 0144

. 0134

. 0124

. 0114

. 0105

. 0165

. 0154

. 0142

. 0131

. 0120

0121 0113

0105 0097

0089

. 0139

. 0129

. 0120

. 0111

. 0101

. 0158

. 0147

. 0136

. 0126

. 0115

30

3234

36

38

40

4244

4648

. 0087

. 0078

.0069

. 0061

. 0051

.0099

. 0089

. 0079

. 0069

. 0059

.0114

. 0103

. 0091

. 0079

. 0068

. 0084

. 0076

. 0067

. 0059

. 0050

.0095

. 0085

. 0076

. 0066

. 0057

. 0109

.0098

. 0087

.0076

.0065

0081 0072

0064

0056

0048

. 0092

. 0083

. 0073

. 0064

. 0055

. 0104

.0093

. 0083

. 0073

. 0062

40

42

44

46

48 50

52

5658

. 0043

.0035

. 0025 .0017

. 0008

. 0049

. 0039

.0029

. 0019

. 0010

. 0056

. 0045

. 0033

.0022

. 0011

. 0041 .0033

. 0025

. 0017

. 0008

.0047

. 0038

. 0028

. 0019

. 0009

. 0054

. 0043

. 0032

. 0022

. 0011

0040

0032

0024

0016

0008

. 0046

. 0036

.0027

. 0018

. 0009

. 0052

.0041

. 0031 .0020

.0010

50

52

5658 Add to observed specific gravity 60

6264

66

68

0. 0000

.0009

. 0017

.0026

. 0034

0. 0000

. 0010

. 0019

. 0029

.0039

0. 0000

.0011

.0022

.0033

. 0044

0. 0000

.0008

.0017

. 0025

.0033

0. 0000

. 0009

.0019

. 0028

.0037

0. 0000

. 0011

. 0021

. 0032

.0042

0. 0000

. 0008

.0016

.0024

.0031

0. 0000

.0009

.0018

. 0027

.0036

0. 0000

. 0010

.0021

. 0031 .0041

60

6264

66

68

70

7274

7678

.0042

. 0051 .0059

. 0068

.0076

. 0048

. 0058

.0067

. 0077

. 0087

.0055

.0066

.0076

.0087

.0098

.0041

.0049

.0057

.0065

.0073

.0046

.0056

.0065

.0074

.0083

.0053

. 0063

. 0074

. 0084

. 0094

0039

0047

0055

0063

0070

.0045

. 0054

. 0063

. 0072

. 0081

.0051

.0061

.0071

.0081

.0091

70

7274

76

78

80

8284

86

88

.0084

. 0092

. 0101 .0109

.0117

. 0096

. 0105

. 0115

. 0124

. 0133

.0108

. 0119

. 0129

. 0140

. 0150

.0081

.0089

. 0097

.0105

.0113

.0092

. 0101

. 0110

.0119

. 0128

. 0104

. 0115

. 0125

. 0135

. 0145

0078

0086

0094

0101 0109

.0089

. 0098

. 0107

. 0115

. 0124

.0101

. 0111

. 0121

. 0130

. 0140

80

8284

86

88

90

9294

96

98

.0125

.0133

.0141

.0150

.0158

. 0142

. 0152

. 0161

. 0170

. 0179

. 0161

. 0171

. 0182

. 0192

. 0203

.0120

. 0128

.0135

.0143

.0150

. 0137

. 0146

. 0155

. 0164

. 0173

.0155

. 0165

. 0175

. 0185

. 0195

0116

0123

0131 0137

0145

. 0133

. 0141

. 0150

. 0159

. 0167

.0150

. 0160

. 0169

. 0179

. 0188

90

92

94

96

98 100

105

110

115 120

.0166

.0186

.0206

. 0224

0244

. 0188

. 0211

. 0234

. 0257

. 0279

. 0213

. 0239

. 0264

. 0289

. 0314

.0158

.0178

.0198

.0215

. 0234

. 0181

. 0203

. 0225

. 0247

.0269

. 0205

. 0230

. 0254

. 0279

. 0303

0153

0172

0191 0209

0227

. 0176

. 0197

. 0218

. 0239

.0260

. 0198

. 0222

.0246

. 0270

.0293

100

105 110

115

120
14 BUREAU OF STANDARDS

IV. HEATS OF COMBUSTION

Determinations of the heat of combustion of petroleum oils are usually made

by means of a bomb calorimeter. The results so obtained yield values of the total heat of combustion at constant volume, which may be defined as the quantity

of heat liberated by the combination of unit quantity of oil with oxygen in a constant

volume inclosure, the products of combustion, carbon dioxide, sulphur dioxide, and

water being cooled to the initial temperature with the water condensed to the liquid

state. This quantity is sometimes called total, gross, or high heating value (calorific

power).

Determinations made by means of calorimeters of the flow type, with the water

formed in combustion remaining in the gaseous state, yield values of the net heat of

combustion at constant pressure. This quantity is sometimes called net or low

heating value (calorific power).

In what follows, it will be convenient to use symbols defined as follows:

Qv =total heat of combustion at constant volume per unit quantity of commercial product; final products: Ash, gaseous C02 , S02 , and liquid H2 0. Qv =net heat of combustion at constant pressure per unit quantity of commercial product; final products: Ash, gaseous C02 , S02 , and H2 0. Q v =total heat of combustion at constant volume per unit quantity of oil free from water, ash,

and sulphur, final products: Gaseous C02 and liquid H2 0. Qp =net heat of combustion at constant pressure per unit quantity of oil free from water, ash,

and sulphur; final products: Gaseous C02 and H2 0. d= Specific gravity at 60°/60° F. %H2 =water content of commercial product in per cent by weight.

%S=sulphur content of commercial product in per cent by weight.

% ash =noncombustible content of commercial product in per cent by weight.

The relation between total heat of combustion at constant volume and specific

gravity selected as best representing the available results on pure hydrocarbons

found in petroleum and on water, ash, and sulphur free petroleum oils is as follows

Q5 = 12,400-2,100 d

2 (1) in which Q„ is expressed in calories per gram. Values of Qv given in Tables 6 and 7 were calculated from this equation. Values in calories per gram multiplied by 1.8 yield values in Btu. per pound, and the latter multiplied by pounds per gallon yield

values in Btu. per gallon.

In most practical applications of the combustion of petroleum products, the process is carried out at constant pressure (atmospheric) and the water vapor formed in

combustion is not condensed. For such processes, therefore, the net heat of combustion at constant pressure is the more significant quantity in making comparisons of

fuels and in calculating the efficiencies of heating appliances.

Since nearly all of the determinations of heat of combustion have been made at constant volume, which are somewhat more precise, the values of net heat of combustion at constant pressure in calories per gram, given in Tables 6 and 7, were calculated by means of the relation

QP = Qv-%H [(9X585)-220] 0.01

in which 9 represents the number of grams of water formed from 1 gram of hydrogen,

585 represents the latent heat of vaporization of water at 20° C. (68° F.), and 220 is a small correction to take into account the change in volume from initial to final
THERM Mi PROPERTIES OP PETROLEUM PRODUCTS 15

products. Average values for percentages of hydrogen in oils of various specific

gravities were obtained from the relation

%H=2Q-15d (2) This relation agrees, within 1 per cent hydrogen, with values obtained from combusv tion analyses of a wide variety of petroleum oils recorded in International Critical

Tables, Vol. II, and also with known values for hydrocarbons of the paraffin series. High accuracy in the values of %H are not needed since the difference between total and net heats of combustion is relatively small, less than 10 per cent. Suppose two oils, A and B, of the same specific gravity contained considerably

different amounts of hydrogen and, in consequence thereof, their total heats of combustion differed by 1 per cent, then their net heats of combustion would differ only

about half this amount as shown by the following

:

Oil %H

Calories per gram

Q° A

B

1312

10, 710

10, 610

10, 052

10, 002

It appears, therefore, that the net heats of combustion of paraffin base and naphthene

base oils of the same specific gravity are more nearly alike than are their total heats of

combustion.

56161°—29 3
16 BUREAJJ OF STANDARDS

1. HEATS OF COMBUSTION OF CRUDE OILS, FUEL OILS, AND KEROSENES

The data on heats of combustion (heating values) given in Table 6 apply to petroleum oils free from water, ash, and sulphur with an estimated accuracy of 1 per cent. These data are based on experimental results obtained, on a total of 630

petroleum oils from 8 States and 10 foreign countries, by 5 groups of observers,

as follows:

Number of samples Authority Reference

50 (1) Bureau of Standards (Unpublished.)

Z. Ver. Deutsch. Ing., 57, p. 1576; 1913. Tech. Paper No. 74; 1914. Bulletin 19; 1911.

J. Am. Chem. Soc, 30, p. 1626; 1908.

109 (2) Constam and Schlapfer . . 252 (3) Bureau of Mines

158 (4) Bureau of Mines 01.— (5) Sherman and Kropff

due allowance being made for the water, ash, and sulphur contents of these oils where

such information was available. With complete data available on water, ash, and

sulphur, the results obtained by (1) and (2) agree with Table 6 within 1 per cent. With incomplete data available on water, ash, and sulphur, 80 per cent of the results obtained by (3), (4), and (5) agree with Table 6 within 1 per cent. Differences

greater than 1 per cent were probably due, in most cases to the presence of undetermined amounts of water, ash, and sulphur.

Many petroleum oils contain only negligible amounts of these foreign materials,

and their heats of combustion may be estimated with fair accuracy from their specific

gravities by means of Table 6. The heats of combustion of petroleum oils containing

appreciable amounts of foreign matter may be estimated by means of the following

relations : _

C, =0.-0.01 <2„(%H2 + %ash + %S) + X(%S)

Q, = Qp -0M Qv {% H20+% ash + % S) + X(% S)-F(% H20)

taking values of Qv and Qp from Table 6 in the particular units desired, corresponding

to the gravity of the oil and values of X and Y in the desired units from the following:

Units X Y

Cal/g 22.5

40.5

338 d

5. 85

10. 53 87.8 d

Btu./lb —

Btu./gal Since the heats of combustion of the hydrocarbon contents of fuel oils differ but little, the usefulness of a fuel oil depends largely upon its cod tent of water, ash,

and sulphur and its viscosity. Minimum water and ash represent freedom from

combustion difficulties, minimum sulphur represents freedom from corrosion, and

minimum viscosity represents freedom of flow. Example i

—What are the heats of combustion (heating values) of a gallon of fuel oil which has

a gravity of 25° A. P. I. at 60° F. and contains 0.5 per cent water, 0.1 per cent ash, and 1.0 per cent sulphur? These may be calculated from the above relations as followsj^ Total heat of combustion at constant volume (total heating value), Qv = 145,000— 1,450(0.5 + 0.1 + 1.0) +338(0.9042) = 142,936 Btu. per gallon. Net heat of combustion at constant pressure (net heating value), Qp = 136,400 — 1,364(0.5+0.1 + 1.0) +338(0.9042) -87.8(0.9042) (0.5) = 134,178 Btu. per gallon.
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 17

Table 6.Heats of combustion of crude oils, fuel oils, and kerosenes

Gravity Density Total heat of combustion at constant volume, Q» Net heat of combustion at constant

pressure, Qp Degrees

Degrees

A. P. I. at 60° F.

Specific

at 60°/60° F. Pounds

per

gallon Cal./g Btu./lb. Btu./gal. Cal./g Btu./lb. Btu./gal.

A. P. I. at 60° F.

10

111213

14

1. 0000

. 9930

. 9861

. 9792

. 9725

8. 337

8. 279

8. 221

8. 164

8. 108

10, 300

10, 330

10, 360

10, 390

10, 410

18, 540

18, 590

18, 640

18, 690

18, 740

154, 600

153, 900

153, 300

152, 600

152, 000

9, 740

9, 770

9, 790

9, 810

9, 840

17, 540

17, 580

17, 620

17, 670

17, 710

146, 200

145, 600

144, 900

144, 200

143, 600

10

1112

1314 15

16

1718

. 9659

. 9593

. 9529

. 9465

8. 053

7. 998

7. 944

7. 891

10, 440

10, 470

10, 490

10, 520

18, 790

18, 840

18, 890

18, 930

151, 300

150, 700

1 r r\ r\c\f\ 150, 000

149, 400

9, 860

9, 880

9, 900

9, 920

17, 750

17, 790

17, 820

17, 860

142, 900

142, 300

141, 600

140, 900

15

16

17

18

19 . 9402 7. 839 10, 540 18, 980 148, 800 9, 940 17, 900 140, 300 19 30

212223

.9340

. 9279

. 9218

. 9159

7. 787

7. 736

7. 686

7. 636

10, 570

10, 590

10, 620

10, 640

19, 020

19, 060

19, 110

19, 150

148, 100

147, 500

146, 800

146, 200

9, 960

9, 980

10, 000

10, 020

17, 930

17, 960

18, 000

18, 030

139, 600

139, 000

138, 300

137, 700

30 21

2223

24 . 9100 7. 587 10, 660 19, 190 145, 600 10, 040 18, 070 137, 100 24 35

26

0*7 Zl2829

. 9042

. 8984

. 8927

. 8871

. 8816

7. 538

7. 490

7. 443

7. 396

7. 350

10, 680

10, 710

1 A TOA

10, 730

10, 750

10, 770

19, 230

19, 270

19, 310

19, 350

19, 380

145, 000

144, 300

1 A O »7AA 143, 700

143, 100

142, 500

10, 050

10, 070

1 A AAA

10, 090

10, 110

10, 120

18, 100

18, 130

18, 160

18, 190

18, 220

136, 400

135, 800

IOC OA

A

135, 100

134, 600

133, 900

35

26

27

28

29 30

31oo3334

.8762

. 8708

. 8654

. 8602 .8550

7. 305

7. 260

7. 215

7. 171

7. 128

10, 790

10, 810

10, 830

10, 850

10, 860

19, 420

19, 450

19, 490

19, 520

19, 560

141, 800

141, 200

1 A A Crtft 140, 600

140, 000

139, 400

10, 140

10, 150

1 A 1 TA

10, 170

10, 180

10, 200

18, 250

18, 280

1 O O 1 A

18, 310

18, 330

18, 360

133, 300

132, 700

1 OO 1 A

A

16Z, 100

131, 500

130, 900

30

3132

3334

35

36

37

38

39

. 8498

. 8448

. 8398

. 8348

. 8299

7. 085

7. 043

7. 001

6. 960

6. 920

10, 880

10, 900

10, 920

10, 940

10, 950

19, 590

19, 620

19, 650

19, 680

19, 720

138, 800

138, 200

137, 600

137, 000

136, 400

10, 210

10, 230

10, 240

10, 260

10, 270

18, 390

18, 410

18, 430

18, 460

18, 480

130, 300

129, 700

129, 100

128, 500

127, 900

35

36

37

38

39 40

4142

4344

. 8251

. 8203

. 8155

. 8109

. 8063

o. o/y

6. 839

6. 799

6. 760

6. 722

10, 970

10, 990

11, 000

11, 020

11, 030

19, 750

19, 780

19, 810

19, 830

19, 860

135, 800

135, 200

134, 700

134, 100

133, 500

10, 280

10, 300

10, 310

10, 320

10, 330

18, 510

18, 530

18, 560

18, 580

18, 600

127, 300

126; 700

126, 200

125, 600

125, 000

4142

43

44 45

46

47

48

49

. 8017

. 7972

. 7927

. 7883

. 7839

6. 684

6. 646

6. 609

6. 572

6. 536

11, 050

11, 070

11, 080

11, 100

11, 110

19, 890

19, 920

19, 940

19, 970

20, 000

132, 900

132, 400

131, 900

131, 200

130, 700

10, 340

10, 360

10, 370

10, 380

10, 390

18, 620

18, 640

18, 660

18, 680

18, 700

124, 400

123, 900

123, 300

122, 800

122, 200

45

46

4748

49

Example 2.—How do the heats of combustion (heating values) of a 15° A. P. I. oil compare

with those of a 30° A. P. I. oil, assuming negligible amounts of water, ash, and sulphur present

in each oil? The following values are obtained from Table 6:

Quantity 15° A. P. I. oil 30° A. P. I. oil Difference

Total heat, Q„ Net heat, Qp.. 151,300

142, 900

141, 800

133, 300

9, 500

9, 600

Thus, the 15° A. P. I. oil has the greater heat of combustion (heating value) by about 7 per cent.
18 BUREAU OF STANDARDS

2. HEATS OF COMBUSTION OF VOLATILE PETROLEUM PRODUCTS

The data on heats of combustion (heating values) given in Table 7 apply to

volatile petroleum liquids in general with an estimated accuracy of 1 per cent. The

values given are probably too high by 1 or 2 per cent for products containing unusually large amounts of aromatic hydrocarbons; for example, " vapor phase cracked"

gasolines. The tabulated values should be increased by about 1 per cent (see Table

15) to yield corresponding values for the heats of combustion of the vapor (vaporized

product) ; that is, for those instances in which the latent heat of vaporization is supplied by the external surroundings and not by the combustion of the product.

The data given in Table 7 are based on experimental results obtained, on a total

of 47 volatile petroleum liquids, by five groups of observers, as follows

Number of samples Authority Reference

10. (1) Bureau of Standards Nat. Advisory Comm. Aeronautics, Report No. 47; 1920. Technical Paper No. 163; 1916. Bulletin No. 43; 1912. The Internal-Combustion Engine, II; 1923.

J. Am. Chem. Soc, 30, p. 1626; 1908.

10 (2) Bureau of Mines

16 (3) Bureau of Mines

8 (4) Bicardo _ 3 (5) Sherman and Kropff—

which constitute all of the data found in the literature on this class of petroleum

products. The results obtained on all of these samples agree with the data given in

Table 7 within 1 per cent, except for the results on four samples, designated here as samples (a), (b), (c), and (d) for convenience. The differences (observed results minus tabulated values) on these samples are as follows: Sample (a) observer (1), — 1.3 per cent; sample (b), observer (2), —1.2 per cent; sample (c) observer (4), — 1.4 per cent; and sample (d) observer (5), +3.4 per cent. Sample (a) was known

to be a "cracked" gasoline, and an analysis of sample (c) indicated a content of 39

per cent aromatics.

Data, taken from International Critical Tables, Volume V, on the total heat of combustion of the following liquid hydrocarbons: Propane, ^so-butane, ^-pentane,

iso-pentane, 7i-hexane, 7i-heptane, w-octane, w-decane, cyclopentane, cyclohexane,

cycloheptane, methylcyclohexane, and 1-1 dimethylcyclohexane, agree with the

data in Table 7 within 0.5 per cent. Example.—What are the heats of combustion (heating values) of liquefied petroleum gas of

specific gravity 0.5517 at 60°/60° F. (125° A. P. I.)? Assuming vaporization at 60° F. and adding

the latent heat of vaporization given in Table 15 to the heats of combustion of the liquid given in Table 7, yields the following values:

Units

Total heat of combustion at constant volume Net heat of combustion at constant pressure

Liquid Vapor Liquid Vapor

Cal/g

Btu./lb

Btu./gal...

11, 760

21, 170 97,400

11, 870

21, 360 98,280

10, 860

19, 560 90,000

10, 970

19, 750 90,880
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 19

Table 7.

Heats of combustion of volatile petroleum products

Gravity Density Total heat of combustion at constant volume, Qv

Net heat of combustion at constant

pressure, Qp Degrees

Degrees

A. P. I. at 60° F.

Specific

at

6O°/60° F. Pounds

per

gallon

Oal./g Btu./lb. Btu./gal. Oal./g Btu./lb. Btu./gal.

A. P. I. at 60° F.

50

5152

5354

0. 7796

. 7753

TT1 1

. 7711

. 7669

. 7628

6. 500

6. 464

6. 429

6. 394

6. 360

11, 120

11, 140

11 1 CA 11, loU

11, 160

11, 180

20, 020

20, 050

OA ATA 20, 070

20, 100

20, 120

130, 100

129, 600

1 OA AAA 129, U00

128, 500

128, 000

10, 400

10, 410

1 A A OA 1U, 42U

10, 430

10, 440

18, 720

18, 740

i q taa lo, toO

18, 780

18, 800

121, 700

121, 100

1 OA AAA LZO, bOO

120, 100

119, 500

50

5152

5354 55

56

CT57

5859

.7587

. 7547

T C AT . 7507

. 7467 .7428

6. 326

6. 292

6. 258

6. 225

6. 193

11, 190

11, 200

1 1 OOA

11, 22U

11, 230

11, 240

20, 140

20, 170 OA 1 AA 20, 190

20, 210

20, 230

127, 400

126, 900

1 OZI A AA 12o, 400

125, 800

125, 300

10, 450

10, 460

1 A A TA 1U, 4/U

10, 480

10, 490

18, 810

18, 830

1 Q Q CA lo, ooU

18, 870

18, 880

119, 000

118, 500

11Q AAA llo, 000

117, 500

116, 900

55

56

5758

59 60

61OZ

63

64

. 7389

. 7351

. /olo

.7275

. 7238

6. 160

6. 128

6. 097

6. 065

6. 034

11,250

11, 270

1 1 OCA 11, ZoO

11, 290

11, 300

20, 260

20, 280

OA QAA ZO, 600

20, 320

20, 340

124, 800

124, 300

1 OO TAA 12o, iOO

123, 200

122, 700

10, 500

10, 510

i a Kon lu, ozo

10, 530

10, 540

18, 900

18, 920

1 Q AOA lo, you

18, 950

18, 960

116, 400

115, 900

lie Ann 110, 4UU

114, 900

114, 400

60

6162

6364

65

66

676869

. 7201

. 7165

T1 OQ . / 12o

. 7093

. 7057

6. 004

5. 973

5. 943

5. 913

5. 884

11,310

11, 320

1 1 QQfl 11, 660

11, 340

11, 350

20, 360

20, 380

OA A AA ZO, 4UU

20, 420

20, 440

122, 200

121, 700

1 01 OAA 121, 200

120, 700

120, 200

10, 540

10, 550

i A Cftn 1U, OoU

10, 570

10, 580

18, 980

18, 990

1 A A1 A

19, 010

19, 020

19, 040

113, 900

113, 400

1 1 O AAA 112, 900

112, 500

112, 000

65

66

67

68

69 70

' 7274

76

78

. 7022

. 6953

COOfi

. DOOO .6819

.6754

5. 855

5. 797

5. 741

5. 685

5. 631

11, 360

11, 380

11 A AA 11, 400

11, 420

11, 440

20, 460

20, 490

OA COA ZO, ooO

20, 560

20, 600

119, 800

118, 800

1 1 T AAA 117, 900

116, 900

116, 000

10, 580

10, 600

1 A tX 1 A

10, OlO

10, 630

10, 640

19, 050

19, 080

19, 100

19, 130

19, 150

111, 500

110, 600

1AA TAA 109, 700

108, 800

107, 900

70

7274

76

78 80

82o4

86

88

. 6690

. 6628

. DODO

. 6506

. 6446

5. 578

5. 526

5. 474

5. 424

5. 375

11, 460

11, 480

11 A AA 11, 490

11, 510

11, 530

20, 630

20, 660

OA CAA

20, 690

20, 720

20, 750

115, 100

114, 200

113, 300

112, 400 111,500

10, 650

10, 670

10, 680

10, 690

10, 700

19, 180

19, 200

19, 220

19, 240

19, 260

107, 000

106, 100

t AC OAA 105, 200

104, 400

103, 500

8082

84

86

88

90

9294

96

98

. 6388

. 6331

. 6275

. 6220

. 6166

5. 326

5. 278

5. 232

5. 186

5. 140

11, 540

11, 560

11, 570

11, 590

11, 600

20, 780

20, 810

20, 830

20, 860

20, 880

110, 700

109, 800

109, 000

108, 100

107, 300

10, 710

10, 720

10, 740

10, 750

10, 760

19, 280

19, 300

19, 320

19, 340

19, 360

102, 700

101, 900

101, 100

100, 300

99, 500

90

9294

96

98 100

105 110

115

120

. 6112

. 5983

. 5859

. 5740

. 5626

4. 988

4. 885

4. 786

4. 691

11, 620

11, 650

11, 680 11,710

11, 740

20, 910

20, 970

21, 020

21, 070

21, 120

106, 500

104, 600

102, 700

100, 900

99, 100

10, 770

10, 790

10, 810

10, 830

10, 850

19, 380

19, 420

19, 460

19, 490

19, 530

98, 700

96, 800

95, 100

93, 300

91, 600

1 ah

105 110

115

120 125

130

135 140

145

. 5517

. 5411

. 5310

. 5212 .5118

4. 599

4. 511

4. 427

4. 345

4.267

11, 760

11, 790

11, 810

11, 830

11, 850

21, 170

21, 210

21, 250

21, 290

21, 330

97, 400

95, 700

94, 100

92, 500

91, 000

10, 860

10, 880

10, 900

10, 910

10, 920

19, 560

19, 590

19, 610

19, 640

19, 660

90, 000

88, 400

86, 800

85, 300

83, 900

125

130 135

140 145
20 BTJREAJJ OF STANDARDS3. HEATS OF COMBUSTION OF GASOLINE-BENZOL MIXTURES

The data on heats of combustion given in Table 8 apply to mixtures of gasoline

and motor benzol with an estimated accuracy of 1 per cent. The values given in the

column marked per cent in Table 8, are the same as those given in Tables 6 and 7 and are based on experimental results described in parts (1) and (2) of this section.

The values for gasoline-benzol mixtures were calculated by means of the following

mixture rules

100 Qm =xQb + (100 -x)Q g 100 Dm =xDb + (l00-x)D g in which the subscripts m, b, and g refer to mixture, benzol, and gasoline, respectively,

and

(2 = heat of combustion in Btu. per gallon,

D = specific gravity at 60°/60°F., x = per cent benzol, by volume.

Values for gasoline given in Table 7 were used in these calculations, together with the

following experimental values for benzol: D = 0.885; Qv = 133,300 Btu. per gallon;

and Qp = 128,100 Btu. per gallon.

Table 8 gives the heat of combustion of the liquid. The net heat of combustion

of the vapor should be used in making comparisons of fuels used in internal-combustion engines, since the latent heat of vaporization is supplied largely by the air or by waste heat from the exhaust gases. Values for the heat of combustion of the

vapor may be obtained by adding the latent heat of vaporization at 60° F., viz, 880

Btu. per gallon of gasoline (see Table 12) and 1,400 Btu. per gallon of benzol. Thus,

for mixtures

X(Btu./gal.) = 14 x + 8.8 (100 -x)

Example.—How do the heats of combustion of a gallon of 57° A. P. I. gasoline compare with

the heats of combustion of a gallon 50° A. P. I. blend of gasoline and 40 per cent benzol? Adding

values of the latent heat of vaporization to the values given by Table 8 gives the following:

Fuel

Total heat of combustion at constant volumeNet heat of combustion

at constant pressure

Liquid Vapor Liquid Vapor

57° A. P. I. gasoline

50° A. P. I. blend

Difference per cent..

126, 400

125, 800 +0.5

127, 280

126, 890 +0.3

118, 000

118, 700 -0.6

118, 880

119, 790 -0.8
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 21

Table 8.Heats of combustion of gasoline-benzol mixtures

> Gravity Total heat of combustion at constant volume in Btu. / gal., Q„. Mixtures containing to 60 per cent benzol, by volume

Degrees

Degrees

A. P. I. at 60° F.

Specific at

bl) /oU x

.

10 20 30 40 50 60

A. P. I. at 60° F.

A A

4142

4344

A QOK1 U. oZoi

. 8203

. 8155

. 8109

. 8063

IOC CAA loo, bUU

135, 200

134, 700

134, 100

133, 500

1 OA CO/l 134, 200

133, 700

133, 100

132, 500

ion qaa loo, oUU

133, 200

132, 700

132, 100

131, 500

loZ, oUU

132, 200

131, 600

131, 000

130, 400

lol, oUU

131, 200

130, 600

130, 000

129, 400

loU, oOO

130, 100

129, 500

128, 900

128, 300

1 OO *7AA lzy, 7UU

129, 000

128, 400

127, 700

127, 100

40

4142

43

44 45

46

47

48

49

. 8017

. 7972

. 7927

. 7883

. 7839

132, 900

132, 400

131, 800

131, 200

130, 700

131, 900

131, 400

130, 800

130, 200

129, 600

130, 900

130, 300

129, 700

129, 200

128, 600

129, 900

129, 300

128, 700

128, 100

127, 500

128, 800

128, 200

127, 600

127, 000

126, 400

127, 700

127, 000

126, 400

125, 800

125, 200

126, 400

125, 800

125, 200

124, 500

123, 800

4546

47

48

49 50

5152

. 7796

. 7753

. 7711

130, 100

129, 600

129, 000

129, 100

128, 500

128, 000

128, 000

127, 400

126, 900

126, 900

126, 300

125, 700

125, 800

125, 200

124, 600

124, 500

123, 900

123, 300

123, 200

122, 600

122, 000

50

5152

5354

. 7669

. 7628

128, 500

128, 000

127, 400

126, 900

126, 300

125, 800

125, 200

124, 600

124, 000

123, 400

122, 700

122, 100

121, 300

120, 700

5354

55

5657

58

59

. 7587

. 7547

. 7507

. 7467

.7428

127, 400

126, 900

126, 400

125, 800

125, 300

126, 300

125, 800

125, 200

124, 700

124, 200

125, 200

124, 700

124, 100

123, 600

123, 000

124, 000

123, 500

122, 900

122, 300

122, 800

122, 800

122, 200

121, 700

121, 100

120, 500

121, 500

120, 900

120, 300

119, 700

119, 100

120, 000

119, 400

118, 800

118, 100

117, 500

55

5657

5859 60 .7389 124, 800 123, 600 122, 500 121, 300 120, 000 118, 500 116, 900 60

Gravity Net heat of combustion at constant pressure iri Btu. / gal., Qp . Mixtures containing to 60 per cent benzol, by volume

Degrees

Degrees

A. P. I. at 60° F.Specific at 60°/60° F. 10 20 30 40 50 60

A. P. I. at 60° F.

40

4142

43

44

0. 8251

. 8203

. 8155

. 8109

. 8063

127, 300

126, 700

126, 200

125, 600

125, 000

126, 700

126, 100

125, 500

124, 900

124, 300

126, 000

125, 400

124, 800

124, 200

123, 700

125, 300

124, 700

124, 100

123, 600

123, 000

124, 700

124, 100

123, 500

122, 900

122, 300

124, 000

123, 400

122, 700

122, 100

121, 500

123, 200

122, 600

122, 000

121, 300

120, 700

40

4142

4344

45

46

47

48

49

. 8017

. 7972

. 7927

. 7883

. 7839

124, 400

123, 900

123, 300

122, 800

122, 200

123, 800

123, 200

122, 600

122, 100

121, 500

123, 100

122, 500

121, 900

121, 400

120, 800

122, 400

121, 800

121, 200

120, 700

120, 100

121, 700

121, 100

120, 500

119, 900

119, 300

120, 900

120, 300

119, 700

119, 100

118, 500

120, 100

119, 400

118, 800

118, 200

117, 600

45

46

47

48

49 50

5152

5354

. 7796

. 7753

. 7711

. 7669

. 7628

121, 700

121, 100

120, 600

120, 100

119, 500

121, 000

120, 400

119, 900

119, 300

118, 800

120, 300

119, 700

119, 200

118, 600

118, 100

119, 500

118, 900

118, 400

117, 800

117, 300

118, 700

118, 100

117, 600

117, 000

116, 400

117, 900

117, 300

116, 700

116, 100

115, 500

117, 000

116, 300

115, 700

115, 100

114, 500

50

5152

5354

55

5657

58

59

. 7587

. 7547

. 7507

. 7467

. 7428

119, 000

118, 500

118, 000

117, 500

116, 900

118, 300

117, 700

117, 200

116, 700

116, 200

117, 500

117, 000

116, 400

115, 900

115, 400

116, 700

116, 200

115, 600

115, 100

114, 500

115, 900

115, 300

114, 800

114, 200

113, 600

114, 900

114, 400

113, 800

113, 200

112, 600

113, 900

113, 300

112, 700

112, 100

111, 500

55

5657

58

59

60 . 7389 116,400 115, 600 114, 800 114, 000 113, 100 112, 100 110, 900 60
22 BTJREAJJ OF STANDARDS

V. SPECIFIC VOLUME OF VAPOR

The data given in Table 9 on specific volume, V, were calculated by means of the

equation, pVM=RT, using standard atmosphere, R = 0.7303, T=°F. + 460,

and values of molecular weight, M, obtained from the equation, ~= 0.0001644 (°A. P. I.) - 0.000972 (3) which is equivalent to M=1.03 (*-43)=oS,

in which v = molecular volume of liquid at 60° F. and d = specific gravity of liquid at 60°/60°F.

The above relations between molecular weight and liquid density are fair approximations for the fighter hydrocarbons, propane, butane, and pentane, and represent an average of the experimental results on petroleum distillates (20° to 80° A. P. I.) obtained by

Observer Reference

Bridgeman

Zeitfuchs Stevenson and Stark. Ormandyand Craven ... Wilson and Wylde

Rittman and Egloff

J. Soc. Auto. Eng., 23, p. 478; 1928. Ind. Eng. Chem., 18, p. 79; 1926. Ind. Eng. Chem., 17, p. 679; 1925.

J. Inst. Petr. Techn., 11, p. 533; 1925. Ind. Eng. Chem., 15, p. 801; 1923. Ind. Eng. Chem., 7, p. 578; 1915. The data given in Table 9 apply to petroleum distillates in general with the fol- lowing estimated accuracies for various ranges of liquid gravity: 20° to 35° A. P. I., 50 per cent; 35° to 50° A. P. I., 25 per cent; 50° to 100° A. P. L, 10 per cent; and

100° to 150° A. P. I., 5 per cent. The tabulated values are probably too high for paraffin-base distillates and too low for naphthene-base distillates and those rich in

aromatics.

Saturation temperatures frequently differ considerably for different petroleum

products of the same gravity. Saturation temperatures or normal dew points are indicated roughly in Table 9 by means of the staggered lines. Many of the values

above the staggered lines are hypothetical values which are useful for rapid estimations

of specific volumes at reduced pressures. The specific volume, V, at any desired temperature and pressure may be obtained conveniently from

v=

V, _ 760V, =

14.77! _ 30V1 2>(atmos.) ^(mmHg) p(lbs./in.2

; abs.) ^(inches Hg)

selecting VY from Table 9, corresponding to the desired temperature and liquid

gravity.

Example.—Crude oil having the following fractional distillation characteristics: 5 per cent over

at 179° F., gravity 75.0° A. P. I.; 10 per cent, 229° F., 68.9° A. P. I.; 15 per cent, 270° F., 63.1° A. P. I.; 20 per cent, 297° F., 58.4° A. P. I.; 25 per cent, 327° F., 55.4° A. P. I.; 30 per cent, 352° F., 52.7° A. P. I.; 35 per cent, 394° F., 49.9° A. P. I., is heated in a fire still at such a rate as to yield 500 gallons of distillate per hour. If the vapor outlet from the still is 12 inches in diameter, what

is the velocity of the vapors? Table 9 indicates that the specific volume of the vapors of each

fraction is approximately 30 cubic feet per gallon of distillate. Thus, 500X30=15,000 cu. ft. per hour flow through an area of -^=0.785 sq. ft. at a velocity of 15,000 r n ei_ 15,000 * « ., 0.785 XS^OO^5' 3 ft

' Per sec' =

0.785X5,280 = 3 ' 6 mlleS p6P h°UP
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 23

Table 9.

Specific volume of petroleum products, completely vaporized at one atmosphere pressure

Gravity Volume of vapor in cu. ft. /lb. at various temperatures in ° F. Degrees

A. P. I. at

60° F.

Specific

at 60°/60° F. 60° 100° 200° 300° 400° 500° 600° 800° 1,000°

0. 9340 1. 8 2. 1 2. 5 25 . 9042 2. 2 • 2.4 2. 9 3. 4 OA30 . 8762 2. 5 I. 8 3. 1 3. 6

A O

4. 2 35 . 8498 2. 7 3. 3. 4 3. 7 4. 4 5. 1

A A . 8251 I. 7O 1 o. 1 6. O 6. 9 4. 3 5. 2 6. 45 . 8017 2. 6 3. 1 3. 6 4. 4. 5 5. 5. 9 6. 9 50

55

. 779b

. 7587

Z. ©

3. 1

6.3.36. 5

3. 9

A f\ 4. U 4.5a a

4. D

5. 1

5. 1 5.7

5. 6

6. 3

6. 7

7. 4

7. 7

8. 6 bv

65 . 7201

Q A 3.79. A 4.0A Q

4. 7

A Q 4t. y

5. 4

K A

6. 1 A O6. 8

A O 7.5

b. 2

8. 9

y. o

10. 4 70

75

. 7022

. 6852

4.4.34. 3

4. 6

5. 1

5. 5

5. 9 6.3

6. 6

7. 1

7. 4

8.

8. 2 8.8

9. 7

10. 5

11. 2

12. 1 80

85

. 6690

. 6536

4. 6

4. 9 5.05. 3

5. 9

6. 3 6.8

7. 2

7. 6

8. 2

8. 5

9. 1

9. 4

10. 1 11. 2

12. 13.

13. 8 90

95

. 6388

. 6247

5. 3

5. 6

5. 7 6.06. 7

7. 1 7.7

8. 1

8. 7

9. 2

9. 7

10. 3

10. 7

11. 3

12. 7

13. 5

14. 7

15. 6 100

110

. 6112

. 5859

5. 9

6. 5 6.3 7.0

7. 5

8. 2

8. 6

9. 5

9. 7

10. 8

10. 8

12.

12.

13. 2

14. 2

15. 7

16. 5

18. 2 120

130

. 5626

. 5411

7. 1

7. 7

7. 7

8. 3

9.

9. 8

10. 4

11. 3

11. 8

12. 8

13. 1 14. 314. 5

15. 8

17. 3

18. 8

20. 21. 8 140

150

. 5212

. 5027

8. 4

9. 9.09. 7

10. 6

11. 4

12. 2

13. 1 13. 814. 9

15. 4

16. 6

17. 1 18. 3

20. 3

21. 8

23. 5

25. 2

Gravity Volume of vapor in cu. ft. /gal. at various temperatures in °F. Degrees

A. P. I. at

60° F.

Specific

at 60760° F. 60° 100° 200° 300° 400° 500° 600° 800° 1,000°

20 0. 9340 14 17 19 25 . 9042 17 18 22 25 30 . 8762 18 20 22 27 31 35 . 8498 19 21 24 26 31 36 40 . 8251 19 21 24 27 30 36 41 45 . 8017 18 21 24 27 30 33 40 46 5055

. 7796

. 7587

18

19

19

21 2325

26

28

30

32 3336

36

39

4347 50

54 60

65

. 7389

. 7201

2122 22

24

26

28

30

32 34

37

38

41 4245

50

54

58

62 70

75

. 7022

. 6852

23

25

25

27

30

31 34

36

39

41 4346

4850 57

60 66

69 80

85

. 6690

. 6536

26

27 2829

333438394344485053

55

636572

75 90

95

. 6388

. 6247

28

29 30

31 3637

414246

48 52

53

57

59 6870

78

81 100

110

. 6112

. 5859

30

32

32

34

38

40 44

46

50

53 5558

616572

77 84

89 120

130

. 5626

. 5411 3335

3638

4244

49

51 5558

6164

68

71

8185 94

98 140

150

. 5212

. 5027

36

38

39

41 4648

53

55 60

62 6770

74

77 88

91 102

106 56161°—29 4
24 BUREAU OF STANDARDS

VI. THERMAL CONDUCTIVITY

The data on thermal conductivity of petroleum liquids, given in Table 10, were calculated from the following equation:

K=^~ [1-0.0003 (*-32)] (4) in which K= thermal conductivity in Btu. per hr., sq. ft., and °F. per in., d = specific

gravity of liquid at 60°/60° F., and £ = temperature in °F. This equation is based on

experimental results obtained at atmospheric pressure on a total of 18 petroleum

oils by 7 different observers as indicated in second part of Table 10. Equation (4) is fairly consistent with most of the available experimental data on

petroleum oils as shown by the percentage differences between observed and cal- culated values. The data in the first part of Table 10 are applicable to petroleum

products at atmospheric pressure with an estimated accuracy of about 10 per cent. The data are probably too low at high pressures, although Bridgman found the

thermal conductivity increased only about 2 per cent per 100 atmospheres at temperatures below 200° F. The data given in Table 10 for paraffin wax are those selected from a critical review of the results of various observers (for references, see International Critical

Tables, Vol. V). Differences in the results for paraffin waxes of different melting

points are comparable with the differences found by various observers for waxes of

the same melting point. The thermal conductivity of paraffin wax decreases slightly

with increased temperature, about 0.1 per cent per °F. and probably decreases

rapidly near the melting point, becoming equal to that for petroleum liquids of corresponding gravity at temperatures above the melting point.

The data given in the first part of Table 10 for asphalt are based on the only

experimental results found in the literature on asphalt practically free from mineral

matter, namely, those obtained by Max Jacob. Considerably higher values were found by Griffiths and by Poensgen for materials which probably contained different

amounts of mineral matter although no quantitative data on the mineral content

are given by these observers.

Example.—The opposite faces of a slab of petroleum asphalt, 3 inches thick, are maintained

at 32° and 77° F., respectively. What is the heat flow per day through each square foot of the

slab? The result is obtained as follows: 1.2X24X1 X^r- = 432 Btu.
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 25

Table 10.

Thermal conductivity of petroleum products

Temperature

Liquids of various gravities Solids

Degrees A. P. I. at 60° F. Amorphous Crystalline

10 20 30 40 50 60

Specific gravity at 60°/60° F. Asphalt Paraffin wax

1.0000 0.9340 0. 8762 0. 8251 0. 7796 0. 7389

°F.6 200 400

600 800

°C. 100 200

300 400

Units: Btu. per hr., sq. ft., and °F. per in.

0. 82 .77

.72

.67

.63

0. 88 .83

.77

.72

.67

0. 94

. 88 .83

.77

.71

1. 00

. 94

. 88

. 82

1. 05 .99

. 93

1. 11 L 05

0. 98

1. 2 | 1. 6 (For temperature

range, 32 °F. to melting point.)

Units: Cal. per sec, cm 2

, and °C. per cm

0. 00028

. 00027

. 00025

. 00024

. 00022

0. 00030

. 00028

. 00027

. 00025

. 00024

0. 00032

. 00030

. 00029

. 00027

. 00025

0. 00034

. 00032

. 00030

. 00028

0. 00036

. 00034

. 00032

0. 00038

. 00036

. 00034

0. 00040 | 0. 00056

(For temperature

range, 0°C. to melting point.)

Experimental data on petroleum oils compared with equation (10)

Observer Number of— Range Difference in per cent

obs.—calc. Reference

Oils Observations Sp. gr. Temp. °F. Average Maximum

Bridgman _ 1 2 (0. 81) 86-167 ±3 +5 0)

(

2

) Van Dusen _ 5 8 0. 86-0. 95 80-200 ±3 + 6 Ernst _ 1 1 (0. 90) 162-194 -3 -3 (

3

) Graetz _ _ _ 1 4 0.788 32-115 ±6 + 13 (

4

) (

5

) Weber __ _ 2 12 0. 78-0. 87 32-95 ±8 + 16 Kave and Higgins _ 4 39 0. 81-0. 90 68-400 ±8 + 18 (

6

)

(

7

) Davis 4 23 0. 81-0. 92 54-167 -8 -27

Experimental data on bituminous substances

Thermal conductivity Observer Material described as

Specific gravity Temp.

°F. Btu. in. Cal. cm

Refer- ence

nr. ft. 2 °F. sec. cm 2 °C. Jacob _ _ _ Bitumen _ _ _ _ / 1. 05 68 1. 16 0. 000400

/ Bitumen used for cementing

1 1. 05 176 1. 19 . 000411

Griffiths ("Not stated. 86 2.9 . 0010

I cork (2 different samples)

.

\Not stated. 86 4. 4 . 0015

Poensgen

f 2. 12 50 4. 5 . 00156

Asphalt used for road-mak- 2. 12 59 4.7 . 00161

ing. 2. 12 68 4. 8 . 00167

[ 2. 12 86 5. 2 . 00178

1 Proc. Am. Academy Arts and Sciences, 59, p. 141; 1923.

2 Bureau of Standards (unpublished).

3 Sitzungberichte Akademie Wissenschaften, Wien, 111, p. 922; 1902.

i Annalen der Physik, 25, p. 337; 1885.

4 Annalen der Physik, 11, p. 1047; 1903.

6 Proc. Royal Soc, London, 117, p. 459; 1928.

7 Philosophical Magazine, 47, p. 1057; 1924.

8 Zeitschrift fur Technische Physik, 7, p. 475; 1926.

6 Proceedings IV International Congress of Refrigeration, London, 1, p. 365; 1924.

10 Zeitschrift des Vereines Deutscher Ingenieure, 56, p. 1653; 1912.
26 BUREA.U OF STANDARDS

VII. SPECIFIC HEAT

The data on specific heat of petroleum oils, given in Tables 12 and 13, were

calculated from the equation

c = (0-388 + 0.00045/) (5)

in which c = specific heat in Btu. per pound per °F., or calories per gram per °C,

d = specific gravity at 60°/60° F., and t = temperature in °F.

This equation is based on over 100 measurements made by the electric heating

method at the Bureau of Standards, within the temperature interval 32° to 400° F., on 30 petroleum oils ranging in specific gravity at 60°/60° F. from 0.75 to 0.96. The

experimental results differ from the values calculated from this equation by less than 2 per cent, on the average, and by about 4 per cent as a maximum. The results on oils from mixed base crudes are in excellent agreement with the calculated values,

whereas the results on oils from paraffin base crudes are systematically higher by

about 2 per cent, on the average, and the results on oils from naphthene base crudes

are systematically lower by about 2 per cent than the values calculated from the

equation. The magnitudes of these systematic differences are consistent with

specific heat data on pure hydrocarbons of the paraffin and naphthene series (see

reference 13, to Table 11).

The bureau's data when extrapolated above 400° F. by means of the equation,

are consistent vrithin about 5 per cent with apparently the only published experimental data extending over the temperature interval 400° to 750° F., namely, those of

Fortsch and Whitman, Zeitfuchs, and Karawajeff.

A brief summary of all the specific heat data on petroleum oils found in the

literature is given in Table 11, which shows that the data obtained by 16 groups of

observers by 5 different methods agree within 5 per cent on the average with values

calculated from the above equation. A critical study of these data has indicated

that differences between observed and calculated values greater than 5 per cent were

not caused by differences in hydrocarbon contents, but were probably caused by one

or more of the following:

(a) Evaporation or condensation (volatile products).

(b) Solidification or liquefaction (distillates containing wax).

(c) Foreign materials, such as water, sulphur, etc. (crudes).

(d) Incorrect evaluation of heat leakage.

(e) Incorrect evaluation of heat capacity of calorimeter or container.

(/) Incorrect temperature measurements.

The specific heat chart prepared by W. R. Eckhart and published in Mechanical

Engineering, 47, p. 539; 1925, gives values at 60° F. which are in good agreement

with the values given in Table 12. Eckhart's values at higher temperatures, however,

are considerably larger, amounting to over 30 per cent at the highest temperatures.
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 27

Table 11.

Data of various observers on specific heat of petroleum oils compared with Bureau of Standards data as expressed by equation (5)

Observer Method

Number

of—

Oils Observa- tions

Range

Sp. gr. 60760° F. Temp. °F.

Difference in per cent Obs.—Calc.

Average Maxi- mum

Probable

cause of large dif- Refer- ence

Siivola__.

Regnault.

Regnault.

Rey

Karawajeff.

Regnault. _ Kuklin

Davis

Brame

Fortsch and Whitman.

Scheller and Georghiu

Graefe Bushong and Knight__ Mabery and Goldstein

Zeitfuchs

Leslie and Geniesse__.

Syniewski.

Heinlein..

IC

M

M

IM

C

M

X

E

B

B

B

IM

E

X

E

111

18

154

1214

11

22

8

5

6

7

5

4

3

2445

1 30

4

12 132

11

64

S2830

723

0. 826

0. 891

0. 891

0. 81

0. 82-0. 92

0. 891

0. 75-0. 87

0. 81-0. 92

0. 72-0. 93

0. 74-1. 00

0. 72-0. 92

0. 71-0. 89

0. 71-0. 99

0. 79-0. 96

0. 78-1. 02

0. 89-0. 92

0. 74-0. 82

0. 74-0. 91

32-205

41-68

60-210

18-244 32-756

64-433

60-104

68-212

54-77

35-554

60-68

60-77

52-176

32-122

77-712

100-300 68-104

77-200

-1.0

-1. 1 -1. 6 ±1.7

±1.8

-1. 9 ±2.

±2. 8 ±2. 8 ±3.

±3. 2 ±3. 5 ±3. 7 ±4.

±4. 6 ±4.8

+8. 3 + 12.

-2.

-1. 8 -2. 1 +4. + 4. 2 -1. 9 -5. 6 -4. 5 -5. 7 + 14. 3 +4. 8 -8. 6 -9. 8 -7. 7 + 10. 2 -15.7

+ 14. 3 +22. 3

(a)

(d) (e)

(c) (d)

(b) (c) (a) (f)

(f)

(a) (d) (e)

0)

(

2

)

(

3

)

(

4)

( 5)

(

6) (

7)

(

8

)

(

9) (10) (u

) (12)

(13)

(14)

(15) (16)

(

17

) (18) (Specific gravity of oil or temperature of experiment not stated; differences estimated by

assuming approximate specific gravity or temperature consistent with general description)

Wales

Redwood

Kuklin

Mabery and Goldstein

Bailey and Edwards. _ Pagliani

Marden and Dover

Sherman, Danziger,

and Kohnstamm

Schmitz

Sullivan, McGill, and

French

M

X

M

IE

M

M

X

X

12

9

22

1

1

117

129

8

26

3

117

10. 64-0. 89

0. 74-0. 76

0. 817

0. 86-0. 95

68

32-122

122-437

64-200

77-86

<5

<5

<5

<5

<5

<5

<5

<5

>5

>5

(b)

(d) (e)

(19)

(20)

(

7

) (14)

(21)

(22)

(23)

(24)

(25)

(26)

Methods: B=bomb calorimeter (heat supplied to oil from combustion of naphthalene, benzoic acid, etc.); C=cooling method

(see Preston's "Theory of Heat," p. 244; 1919 ed.); E=electric heating method; I =ice calorimeter; M=method of mixtures; and X=method not stated.

1 Oversikt av Finska Vetenskaps—Societetens Forhandlinger, 56, No. 8, p. 7; 1913-14.

2 Annales de Chimie et Physique, 9, p. 349; 1843.

3 Annales de Chimie et Physique, 73, p. 5; 1840.

i Annales des Mines, 8, p. 68, 1925.

« Petroleum Zeitschrift, 9, p. 1114; 1914.

6 Memoires de leAcad'mie Sciences, France, 26, p. 262; 1862.

7 Berichte der Deutschen Chemischen Gesellschaft, 16, p. 949; 1883.

« Philosophical Magazine, 47, p. 1057; 1924.

9 B. Redwood's "Treatise on Petroleum," I, p. 222; 1913.

i° Industrial and Engineering Chemistry, 18, p. 795; 1926. « Petroleum Zeitschrift, 8, p. 533; 1913. " Petroleum Zeitschrift, 2, p. 521; 1907.

13 Ind. & Eng. Chem., 12, p. 1197; 1920.

ii Proc. Am. Acad. Arts & Sci., 37, p. 539; 1913.

is Ind. & Eng. Chem., 18, p. 79; 1926. " Ind. & Eng. Chem., 16, p. 582; 1924.

1 7 Zeitschrift fur Angewante Chemie, 11, p. 621; 1898.

is Der Motorwagen, p. 75; Feb. 10, 1926. w Ind. & Eng. Chem., 6, p. 727; 1914.

20 1. 1. Redwood's, Mineral Oils and Their By-Products, p. 200; 1897. » Ind. & Eng. Chem., 12, p. 892; 1920.

22 Atti dela reale accademia delle scienze di Torino, 17, p. 97; 1881. » Ind. Eng. Chem., 9, p. 860; 1917.

24 J. Am. Chem. Soc, 24, p. 269; 1902.

25 Les Matieres Grasses, Jan. No. 58, p. 3005; 1913.

2« Ind. & Eng. Chem., 19, p. 1040; 1927.
28 BURE/UJ OF STANDARDS

1. SPECIFIC HEAT OF PETROLEUM OILS OF VARIOUS GRAVITIES IN BTU./LB. °F. OR CAL./G °C. The data given in Table 12 represent average' values based on measurements

described on page 26. The estimated accuracy of the tabulated data as true specific

heats at a constant pressure of 1 atmosphere is 5 per cent. The data are probably- somewhat too low for pressures much above 100 lbs. /in.2 The data do not take into

account such quantities as latent heat of fusion, latent heat of vaporization, and

heat of reaction (cracking).

Since the relation between true specific heat and temperature is linear, the mean

specific heat between any two temperatures is equal to the true specific heat at the

mean temperature.

Example—What are the true specific heats of a 30° A. P. I. oil (a) at 100° F., (6) at 500° F., and (c) what is the mean specific heat between 100° and 500° F.? The following values are obtained

from Table 12: (a) true specific heat at 100° F. = 0.463; (h) true specific heat at 500° F. =0.655;

(c) mean specific heat between 100° and 500° F. = 0.559.

2. SPECIFIC HEAT OF PETROLEUM VAPORS

There are in the literature practically no data on the specific heat of petroleum

vapors. Approximate values for the specific heat at constant pressure (moderate

pressures) may be obtained from the relation

in which L = latent heat of vaporization, t = temperature, Cg = specific heat of gaseous

phase at constant pressure, and Ct = specific heat of liquid phase.

Evaluating the rate of change of latent heat of vaporization with temperature

from equation (6) given in Section VIII, gives

at 0.09

d

where d = specific gravity at 60°/60° F. of the liquid corresponding to the condensed

vapor.

Example.—What is the specific heat at a constant pressure of one atmosphere of 60° A. P. I. gasoline vapor at 400° F.? An approximate value may be obtained as follows:

x Co = 0.661-

Q°

7339 =0.54 Btu./lb. °F. Note added to proof.—The recent experimental values obtained by Bahlke and Kay

(Ind. & Eng. Chem., 21, p. 942; 1929) agree with values calculated as outlined above within

about 3 per cent on the average.

Cg =Ci —
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 29

Table 12.

Specific heat of petroleum oils of various gravities in Btu./lb.°F. or cal./g °C.

Temp. °F.

Degrees A. P. I. at 60° F.

Temp. °F. 10 20 30 40

| 50 60 70 80

Specific gravity at 60°/60° F.

1.0000 0.9340 0. 8762 0. 8251 0. 7796 0. 7389 0. 7022 0. 6690

20

40

6080

100

120 140

160

180 300

220

240

260

280

300

320

340

360

380

40©

420

440

460

480

500

520

540

560

580

600

620

640 680

700

720

740

760

780

800

0.388

.397

. 406

.415

.424

.433

.442

.451

.460

. 469

.478

.487

. 496 .505

.514

.523

. 532

. 541 .550

.559

.568

. 577 .586

.595

.604

.613

. 622

.631

.640

.649

. 658

. 667

. 676

. 685

. 694

. 703

. 712

. 721 .730

.739

.748

0.401

.411

. 420

. 429

.439

.448

.457

. 467

. 476

.485

.495

. 504

. 513

. 523

.532

.541

.550

. 560

.569

.578

.588

.597

. 606

. 616

.625

.634

. 644

.653

. 662

. 672

. 681

. 690

. 699

. 709

.718

. 727

. 737

. 746

. 755

. 765 .774

0. 415

. 424

. 434

. 443

. 453

. 463

. 472

. 482

. 491 .501

.511

. 520

. 530

. 540

. 549 .559

. 568

. 578 .588

. 597

. 607

. 616

. 626

. 636

. 645 .655

. 665 .674

. 684

.693

.703

. 713 .722

. 732 .741

.751

. 761 .770

.780

.790

.799

0. 427

. 437

. 447

. 457

. 467

. 477

. 487

. 497

. 506

. 516

. 526

. 536

. 546

. 556

. 566

. 576

. 586

. 596

. 606

. 615

. 625

. 635

. 645

. 655

. 665

. 675

. 685

. 695

. 705 .715

. 724

0. 439

. 450

. 460

. 470

. 480

. 490

. 501

. 511

. 521 .531

. 541

. 552

. 562

. 572

. 582

. 592

. 603

. 613

. 623

. 633

. 643

. 653

. 664

. 674

. 684

. 694

0. 451

. 462

. 472

. 483

. 493

. 504

. 514

. 525

. 535

. 546

. 556

. 567

. 577

. 588

. 598

. 609

. 619

. 629

. 640

. 650

. 661

0. 463

. 474

. 485

. 495

. 506

.517

. 527

. 538

. 549

. 560

. 570

. 581

. 592

. 603

. 613

. 624

0. 474

. 485

. 496

. 507

. 518

. 529

. 540

. 551

. 562

. 573

. 584

2040

60

80 100

120 140

160 180 200

220

240

260 280 300

320

340

360

380 400

420

440

460

480
30 BUREAU OF STANDARDS

3. SPECIFIC HEAT OF PETROLEUM OILS OF VARIOUS GRAVITIES IN BTU./GAL. °F. The data given in Table 13 represent average values based on measurements

described on page 26. For statements regarding the estimated accuracy and the

limitations of the tabulated data, see page 28. The unit of mass used in Table 13 is

1 gallon of oil at 60° F.

Example.—How much heat is required to produce a change of 1° F. in the temperature of a

gallon of 30° A. P. I. oil (both referred -to 60° F.) : (a) When oil is at 100° F.; (6) when oil is at 500° F.? The following values are obtained from Table 12: (a) 3.38 Btu. at 100° F.; (6) 4.78 Btu.

at 500° F.

4. SPECIFIC HEAT OF PETROLEUM ASPHALT

Measurements of specific heat by the method of mixtures have been made at the Bureau of Standards on one sample of petroleum asphalt having the following

characteristics: Specific gravity at 77° F., 1.044; melting point (ball and ring method),

125° F.; loss after five hours at 325° F., 0.1 per cent; penetration at 77° F., 67 before

heating, 60 after heating; soluble in carbon disulphide, 99.6 per cent; ash, 0.1 per

cent. No evidence was found of any irregularity in the specific heat between — 100°

and +300° F., which indicates that petroleum asphalt may be regarded thermally as a subcooled liquid with no heat of transformation from liquid to apparent solid. The measurements on this sample agree within 2 per cent with the data given in

the 10° A. P. I. columns of Tables 12 and 13, which indicates that the data in these

columns are probably applicable to petroleum asphalts and to the bitumen content

of natural asphalts. This indication is confirmed by the measurements of Zeitfuchs

(see reference 15 on page 27) on a California asphalt, 70 penetration, specific gravity

1.013, and by the measurements of A. W. Dow (Municipal Engineering, 27, p. 22;

1904) on the following refined natural asphalts: Trinidad, Maracaibo, Cuban, and

Bermudez.

In many practical applications, petroleum asphalt is mixed with various amounts

of solids, such as sand, crushed rock, etc. The specific heat of such mixtures may

be obtained from the equation

Om = 0,01[(100 -x) Ca +xCs] (5a)

in which cc = per cent, by weight, of solids, C= specific heat, and the subscripts, a, s, and m refer to asphalt, solid, and mixture, respectively. The relation, (7S = 0.18 +

0.00006t° F., may be used for the solid constituents. (See International Critical

Tables, Vol. II, pp. 55, 63, and 128 for experimental data.) Values for Ca may be

taken from 10° A. P. I. column of Table 12. Example.—What is the specific heat at 60° F. of bituminous material containing by weight

15 per cent asphalt and 85 per cent solid materials? Table 12 and the above relations give

Cm =0.01 (15X0.415) + (85X0.184) =0.22. Kinoshita (Gesundheits-Ingenieur, 39, p. 497; 1916) obtained 0.22 for the mean

specific heat between 32° and 68° F. of an " asphalt" of specific gravity 2.10. No

further description of the material is given. The values for specific heat and specific

gravity are consistent with the data in the above example.
THERMAL PROPERTIES OF PETROLEUM PRODUCTS

Table 13.

Specific heat of petroleum oils of various gravities in Btu./gal. °F. 31

Temp. ° F. 10 20 30 40 50 60 70 80

Specific gravity at 60°/60° F.

Degrees A. P. I. at 60° F.

1.0000 0.8762 0.8251 0.7796 0.7389 0.7022 0.6690

20

40

6080 100

120

140

160

180 200

220

240

260

280 300

320

340

360 380

400

420

440 460

480 500

520 540

560

580 600

620 640

660

680

700

720

740

760

780 800

3. 23

3. 31

3. 38

3. 46

3. 53

3. 61

3. 69

3. 76

3. 84

3. 91

3. 99

4. 06

4. 14

4. 21

4. 29

4. 36

4. 44

4. 51

4. 59

4. 66

4. 74

4, 81

4. 89

4, 96

5. 04

11192634

4149

56

64

7179

5. 86

5. 94

6. 01

6. 09

6. 16

6. 24

3. 13

3. 20

3. 26

3. 33

3. 41

3. 49

3. 56

3. 63

3. 71

3. 78

3. 85

3. 92

4. 00

4. 07

4. 14

4. 21

4. 29

4. 36

4. 43

4. 50

58

65

727987

94

0108

162330

37

45

5259

66

74

8188

95

6. 03

3. 03

3. 10

3. 17

3. 24

3. 31

3. 38

3. 45

3. 52

3. 59

3. 66

73

8087

3. 94

4. 01

4. 08

4, 15

4. 22

4. 29

4. 36

4. 43

4. 50

4. 57

4. 64

4. 71

4. 78

4. 85

4. 92

4. 99

5. 06

5. 13

5. 20

5. 27

5. 34

5. 41

5. 49

5. 56

5. 63

5. 70

5. 77

5. 84

2. 94

3. 01

3. 07

3. 14

3. 21

3. 28

3. 35

3. 41

3. 48

3. 55

3. 62

3. 69

3. 75

3. 82

3. 89

3. 96

4. 03

4. 09

4. 16

4. 23

4. 30

4. 37

4. 44

4. 50

4. 57

4. 84

4. 91

4. 98

92

2.2.

2. 99

3. 06

3. 12

3. 19

3. 25

3. 32

3. 39

3. 45

3. 52

3. 58

3. 65

'3. 72

3. 78

3. 86

3. 93

3. 99

4. 06

4. 12

4. 1926

323946

4. 52

2. 78

2. 85

2. 91

2. 97

3. 04

3. 10

3. 17

3. 23

3. 30

3. 36

43

49

55

6268

3. 75

3. 81

3. 88

3. 94

4. 01

4. 07

2. 71 2. 65

2. 77 2. 71

2. 84 2. 77

2. 90 2. 83

2. 96 2. 89

3. 02 2. 95

3. 09 3. 01

3. 15 3. 08

3. 21 3. 14

3. 28 3. 20

3. 34 3. 26

3. 40

3. 46

3. 53

3. 59

3. 65
32 BUREAU OF STANDARDS

VIII. LATENT HEAT OF VAPORIZATION

The data on latent heat of vaporization of petroleum oils, given in Table 15, were

calculated from the equation

Z=|(110.9-0.09f) (6)

in which Z = latent heat of vaporization in Btu./lb., c£ = specific gravity of liquid at 60°/60° F., and t = temperature in °F. This equation is based on calorimetric measurements found in the literature on latent heat of vaporization of petroleum distillates,

all of which are enumerated briefly in the first part of Table 14. All of these measurements were made at atmospheric pressure, except for those

of Rey, which extended to a pressure of 7 atmospheres. In the experiments of Syniewski, Ormandy and Craven, Regnault, and Kuklin, petroleum vapors were condensed in a water calorimeter. Their results yielded, therefore, values of total heat of vaporization from liquid at room temperature to vapor at 1 atmosphere

pressure. These observed values were reduced to latent heats of vaporization for the purpose of comparison (Table 14), by means of the data on specific heat of liquid

given in the previous section. The values of latent heat so obtained differ somewhat

from those reported by the various authors, because, in one case, an arbitrary value

for specific heat was used and, in other cases, the increase of specific heat with

temperature was neglected.

Equation (6) is fairly consistent with most of the available experimental data on petroleum distillates as shown by the percentage differences between observed

and calculated values. The results obtained by Heinlein are obviously inconsistent

with the results of other observers. This was probably caused, in part at least, by

the fact that there was good opportunity for reflux condensation in Heinlein's

experiments.

Equation (6) yields values which differ less than 10 per cent, on the average,

from experimental results obtained at 1 atmosphere pressure on the following hydrocarbons: n-hexane, 4-methylheptane, cyclohexane, and methylcyclohexane (Mathews,

J. Am. Chem. Soc, 48, p. 562; 1926); n-hexane, 7i-heptane, n^pctane, hexamethylene,

dimethylpentamethylene, methylhexamethylene, and dimethylhexamethylene (Mar

bery and Goldstein, Proc. Amer. Acad. Arts and Sci., 37, p. 549; 1902); n-decane

(Louguinine, Ann. Chim. phys., 13, p. 289; 1898).

In addition to being in general accord with the available experimental results on petroleum distillates and individual petroleum hydrocarbons, equation (6) is in

fair agreement with about the only existing evidence on the magnitude of the variation of latent heat with temperature or pressure over a considerable range below the

critical point as shown by the second part of Table 14. There are in the literature numerous values for the latent heat of vaporization

of petroleum distillates, some of which were calculated by means of Trouton's rule

from measurements of " apparent" molecular weight and "average" boiling point

of the distillates, while others were obtained from data on pure substances by means

of Trouton's or Hildebrand's rule. The values so obtained are uniformly higher

than those found by calorimetric measurements on petroleum distillates, amounting

in some cases to nearly 100 per cent. Probably the major reasons for the higher

values are (1) that Trouton's and Hildebrand's rules are not applicable to complete

vaporization of mixtures with a wide range of boiling points, and (2) that the

"apparent" molecular weights of the heavier distillates are too low.
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 33

Table 14.

Comparison of observed and calculated values of latent heat of vaporization of petroleum

distillates and pure hydrocarbons

Observer Method

Range

Sp. gr. Temp.

°F.

Number

of—

Oils Observa- tions

Difference in per

cent obs.-calc.

Average Maxi- mum

Refer- ence

Syniewski

Gurwitsch

Ormandy and Craven.

Leslie, Geniesse, Legatski and Jagrawski. Regnault

Key

Kuklin

Redwood

Heinlein

Mixtures

Not stated- ___

Mixtures

Electric heating

Mixtures

Not stated Mixtures

Not stated

Electric heating

0. 74-0. 83

. 64- . 81

. 70- . 75

. 68- . 82

.89

.81 74- . 76 64- . 81 74- .91

212-470

104-348

232-250

152-576

536 347-527

200-235

70-260

194-345

7

6

317

1117

423

±2

-4

±4

±6+7 +9 + 12 ±19 + 40

-6

-9

-10

+ 10 + 10 + 16 + 19 -39

+70

0)

(

2)

(

3

) (

4 )

(

5

)

(

6

) (

7

)

( 8

) (

9

)

Temperature

C.

Pressure Latent heat

Observations 10 Calculations

Difference

in per

cent obs.-

calc.

Pressure atmos.

Latent heat

Observations 10 Calculations

Difference

in per

cent obs.-

calc. Temp.

° C.

(Normal pentane)

2040

6080

100

120

140

160

180

2040

6080

100

120

140

160

180 200

220

240 260

280

32

68

104 140 176 212

248

284

320

356

32

68

104

140

176 212

248

284

320

356

392 428

464

500 536

0. 24

. 55

1. 12

2. 11

3. 60

5. 80

8. 87

13.

18. 5

25. 5

168

160

152 144

136

126 116

10285

63

171 166

161 156

151 145

140

135 130

125 (Normal heptane)

0. 015 .05

. 12

. 27 .56

1. 05

1. 80

2. 92

4. 54

6. 70

9. 56

13. 3

18. 1 24. 3

162

158 154 149

143

136

129

121 113

105

84

67

39

157

152 148

143 138

133

129 124

119 115

110

105 10096

-2

-4

-6

-8

-11

-15

-21

-32

-53

-98

+3

+3 + 4 +4 +3 +2 -2

-5

-9

-15

-25

-49

-146

0. 06

. 16

. 36

. 75

1. 40

12.

42

9206

94

7

(Normal hexane)

164

158

152

145

140 132

125 115 10492

163 158

153 148

143

138

133

129 124

119 (Normal octane)

+ 1 -1

-2

-2

-4

-6

-12

-19

-29

0. 004

. 014

. 04

. 10

. 23

. 46

. 85

1. 47

2. 38

3. 65

5. 39

7. 73

10. 8

14. 7

19. 7

2040

60

80 100

120 140

160 180

161 153 +5

156 148 +5 20

150 144 +4 40

145 139 +4 60

139 134 +4 80

134 130 +3 100

129 125 +3 120

123 121 +2 140

117 116 + 1 160

110 112 -2 180

101 107 -6 200

94 102 -9 220

83 98 -18 240

70 93 -33 260

51 89 -75 280

1 Zeitschrift fur Angewante Chemie, 11, p. 621; 1898.

2 " Wissenschaftliche Grundlagen der Erdolverarbeitung," 2d ed., p. 144; 1924 (J. Springer, Berlin).

3 J. Inst. Petroleum Technologists, 9, p. 368; 1923.

* Ind. & Eng. Chem., 18, p. 45; 1926.

* Memoires de l'Academie Sciences, France, 26, p. 913; 1862.

8 Annales des Mines, 8, p. 53; 1925.

7 Berichte der Deutschen Chemischen Gesellschaft, 16, p. 949; 1883.

8 "Mineral Oils and Their By-Products" p. 200; 1897 (E. and F. N. Spon (Ltd.), London).

» Der Motorwagen, p. 395, June 30, 1926.

10 Observed values in Btu./lb. obtained from experimental data on vapor pressure and specific volume by means of Clapeyron

equation. (Young, Proc, Royal Dublin Soc,, 13, p. 374; 1910; also Mills, J. Am. Chem. Soc, 31, p. 1099; 1909.)
34 BUREAU OF STA.NDA.RDS

VIII. LATENT HEAT OF VAPORIZATION—Continued

The experimental basis for the data given in Table 15 is described on the preceding

pages. The following equation

£(Btu./lb.) =| (110.9 - 0.090 was found to represent satisfactorily most of the experimental results available on

petroleum distillates. This equation yields the following convenient relation

Z(Btu./lb.) X density (Ibs./gal.) =8.33722 Ld = 925 - 0.75£ (Btu./gal.) (7)

which indicates that the latent heat of vaporization per unit volume of liquid (60° F.)

is dependent only on the temperature of vaporization. Thus, the values given in

the second column of Table 15 are applicable to any petroleum oil, regardless of gravity. The values given in the other columns are applicable, in general, to all cases of vaporization of petroleum products in which the temperature of vaporization

and the gravity of the condensate are known.

The estimated accuracy of the data in Table 15 is 10 per cent, when vaporization

occurs at sensibly constant temperature and at pressures below 50 lbs. /in.2

, without

chemical change. The tabulated values are probably too low by more than this

amount for petroleum products containing large quantities of the lower members of

the aromatic series and too high for vaporization at high pressures, as is illustrated in

Table 14. Example 1. —What is the difference between the latent heats of vaporization of a 50° and a

70° A. P. I. gasoline, assuming complete vaporization occurs at 140° F. in the intake system of an

internal-combustion engine? According to Table 15, on a weight basis the difference in latent heats amounts to 140 — 126 = 14 Btu./lb. or about 10 per cent, while on a volume basis both gasolines

require 820 Btu./gal.

Exam-pie 2.—How much latent heat is required to vaporize or condense various petroleum

products at the average temperatures indicated below?

Product Gravity,

°A. P. I. Average

temperature °F.

Latent heat from

Table 15

Btu./lb. Btu./gal.

Gasoline.. 6050

40

30

280

340 440

580

116 10386

67

715 670

595 490 Naphtha

Kerosene

Fuel oil
THERMAL PROPERTIES OF PETROLEUM PRODUCTS

Table 15.

Latent heat of vaporization of petroleum oils 35

Temp. F.

2040

6080

100

120 140

160 180 300

220

240

260

280

320

340

360 380

400

420

440

460 480

500

520

540

560

580

600

620

640

660 680

700

720

740

760

780 800

Latent

heat

10°-80° A. P. I. oils Btu./gal.

925

910 895

880 865

850

835 820

805

790

775 760

745 730

715 700

685

670

655 640

625 610

595

580

565 550

535 520

505

490

475

460 445

430

415 400

385

370

355 340

325

Latent heat of oils of various gravities in Btu./lb.

20

0.9340

9088

8684

82

8078

7674

73

716967

65

63

6159

57

55

53

5149

47

45

44

42

30

0.8762

106

104

102

10098

9694

92

9088

85

83

8179

77

75

73

7169

67

6563

615957

55

53

514846

44

Degrees A. P. I. at 60° F. 40 50 60

Specific gravity at 60°/60° F.

0.8251 0.7796 0.7389

123

121 119 117

115 113

110

108 106

104

1029997

95

93

9189

8684

8280

78

75

73

7169

142

140

138

135 133

131 128

126 124

121 119

117

115 112 110

108

105

103

101

9694

9189

87

85

150 148

145 143

140 138

135

133

131 128 126

123

121 118 116

113

111 109

106 104

101

70 80

158

155 153

150 148

145

143

140 137

135

132

130 127

125 122 119

Temp. F.

0.7022 0.6690

166

163 160

158

155 152

150

147 144

142

139

20

40

60

100

120

140

160

180 200

220

240 260

280 300

320

340 360

380 400

420

440

460 480
36 BUREAU OF STANDARDS

IX. HEAT CONTENT

Calculations of the quantities of heat involved in the heating and cooling of

fluids are very simple when use is made of the thermodynamic function called heat

content (also called total heat and enthalpy). For this reason, data on specific and

latent heats have been combined to yield the heat content data given in Tables 16

and 17. Strictly speaking, the data in these tables represent heat content at 1 atmosphere pressure, since they are based on measurements made at atmospheric pressure. The magnitude of the change of heat content with pressure (temperature constant) is small, however, being comparable with the estimated accuracy of these data in

general for pressures below 1,000 lbs. /in. 2

.

The experimental basis for the data on heat content of petroleum liquids, given in

Table 16, is the same as for the specific heat data described in Section VII. Differ- ences in heat content between 32° F. (or 77° F.) and higher temperatures have been

directly measured by numerous observers. The agreement of the observed results and the tabulated values is shown in Table 11. Following usual practice, the heat content of liquid has been arbitrarily assigned

the value zero at 32° F. Thus, for all practical purposes, the heat content of petroleum

liquids, Hi is given by the equation

since the heat equivalent of the external work, pdv, is so small that it may well be

neglected here. Integrating the equation for specific heat, c, given on page 26, and

multiplying by 8.33722(2 to reduce to a volume basis, gives the following equation

for heat content in Btu./gal.

in which d = specific gravity of liquid at 60°/60° F. and t = temperature in °F. This

equation was used to calculate the data given in Table 16. The estimated accuracy of the data in Table 16 as heat content at 1 atmosphere

pressure is 5 per cent. The data are probably too low by more than this amount in

the neighborhood of the critical point. The data do not take into account such

quantities as latent heats of fusion and vaporization and heats of chemical reaction.

1. HEAT CONTENT OF PETROLEUM LIQUIDS

cdt

Fz = V<Z(3.235* + 0.0001875*2 - 105.5) (8)
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 37

2. HEAT CONTENT OF PETROLEUM VAPORS

The data on heat content of petroleum vapors, given in Table 17, were calculated

from the following equation

^= V^(3 - 23 ^ + - 00187^2 - 105 - 5 ) + 925 -°-7^ ( 9 ) which represents a combination of heat content of liquid, equation (8), and latent

heat of vaporization, equation (7). Thus the data on heat content of vapor represent

values above that of the heat content of liquid at 32° F. The experimental basis for the data in Table 17 is the same as for the specific and

latent heat data described in Sections VII and VIII. It may be noted that the heat

content of petroleum vapors above that of liquid at room temperature has been

directly measured by Syniewski, Ormandy and Craven, Regnault, and Kuklin.

(See Table 14 for references.) The results obtained by these observers are consistent with the data in Table 17 within 5 per cent on the average.

Wilson and Barnard (Ind. & Eng. Chem., 13, p. 912; 1921) determined the

heat content of gasoline and kerosene vapor at atmospheric pressure by heating these

vapors to temperatures of 550° to 850° F. and measuring the heat given up in changing

to liquid at room temperature. Their results agree within 10 per cent with the

data given in Table 17. The agreement is within 5 per cent when account is taken of

the fact that the specific heat of the saturated vapor is less than that of the liquid

(see Sec. VII (2)), and that specific heats of superheated vapors increase less rapidly

with temperature, in general, than do those of liquids.

The accuracy of the data in Table 17, estimated solely from the agreement

with all of the rather meager experimental data available on petroleum vapors and

from known data on the properties of pure substances, is as follows: 5 per cent for vapor saturated at atmospheric pressure or below; 10 per cent for vapor saturated

at any temperature and pressure; 15 per cent for vapor at any pressure and superheated by any amount. The data do not take into account heats of chemical

reactions.

As pointed out in Sections VII and VIII, the specific heat data are too low and

the data on latent heat of vaporization are too high for the higher pressures. There

is considerable compensation, therefore, in the resultant values for heat content. There is an analogous compensation in the case of vapors rich in aromatics,
38 BUREAU OF STANDARDS

Table 16.

Heat content of petroleum liquids of various gravities in Btu./gal. 1

Degrees A. P. I. at 60° F.

10 20 30 40 50 60 70 80

Temp. P. Temp. F.

Specific gravity at 60760° F.

1.0000 0. 9340 0. 8762 0. 8251 0. 7796 0. 7389 0. 7022 0. 6690 -105 -102 -99 -98 -93 -91 -88 -86

10 -73 -70 -68 -66 -64 -63 -61 -60 10 20 -40 -39 -37 -38 -35 -34 -34 -33 20 32 32 40 -1-27 J_ OAzu JL9K 4.04 J-94 + 23 +22 40 50 61 59 57 55 54 52 51 50 50

60 95 92 89 86 84 82 80 78 60 70 130 126 122 118 115 112 109 106 70 80 165 160 155 150 146 142 138 135 80

90 901 1J. Q4art 1J. RR00 182 1 77 173 168 1 R4 90 100 237 229 222 215 209 204 198 194 100

110 273 264 256 248 241 235 229 223 110

120 310 300 290 281 273 267 260 253 120

' 130 347 335 325 315 306 299 291 284 130 140 3R4 Oil 971 ouu oio ^4Q OOu 331 322 Olrt 31 4 140 150 422 408 395 383 372 363 354 345 150

160 460 445 431 418 406 396 386 376 160

170 499 482 467 453 440 429 418 408 170

180 538 520 503 488 475 462 451 440 180 190 OlK77I OOo ^4A 0Z3: ouy 4R4 479 11 6 190 200 617 596 577 560 544 530 517 504 200

210 657 635 615 596 580 564 550 537 210 220 697 674 652 633 615 599 584 570 220

230 738 713 691 670 651 634 618 603 230

240 / /y / OO / zy i\Ji Doo ooy OOo Do I 240 250 820 793 768 745 724 705 688 671 250

260 862 833 OAT 807 TOO 783 7bl *i a 1 741 700 /Do 260

270 904 874 847 822 799 778 758 740 270

280 947 915 887 861 836 814 794 775 280 290 990 957 927 900 874 851 830 810 290

300 1, 034 999 968 939 913 889 866 846 300

310 1, 078 1, 041 1,009 979 952 926 903 881 310

320 1, 122 1. 084 1, 050 1, 019 991 964 940 917 320

OOU 1, 166 1, 127 1, 092 1, 059 1, 030 1, 002 977 954 330

340 1, 211 1, 170 1, 134 1, 100 1, 070 1, 041 1, 015 981 340 350 1, 256 1, 214 1, 176 1, 141 1, 110 1, 080 1, 053 1, 028 350

360 1, 302 1, 258 1, 219 1, 183 1, 150 1, 119 1,091 1, 065 360

370 1, 348 1, 303 1, 262 1, 225 1, 190 1, 159 1, 130 1, 103 370

380 1, 395 1,348 1, 306 1, 267 1, 231 1, 199 1, 169 1, 141 380

390 1, 441 1, 393 1, 349 1, 309 1, 273 1, 239 1, 208 1, 179 390 400 1, 489 1, 439 1, 393 1, 352 1, 314 1, 280 1, 247 1, 217 400

1 The unit used here is 1 gallon of oil at 60° F. See page 36 for statements regarding the experimental basis for these data and

their estimated accuracy. Example.—Row much heat is required to raise the temperature of a 30° A. P. I. oil from 70° to 500° F.? The result is obtained from Table 16 as follows: Heat content at 500° F. = 1,8.54 Btu./gal. Heat content at 70° F. = 122 Btu./gal. Heat required = difference = 1,732 Btu./gal.
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 39

Table 16.Heat content of petroleum liquids of various gravities in Btu.fgal.—Continued

Degrees A. P. I. at 60° F.

Temp. F. 10 15 20 25 30 35 40 45

Temp. F.

Specific gravity at 60760° F.

1.0000 0. 9659 0. 9340 0.9042 0. 8762 0.8498 0. 8251 0. 8017

400

410

420

430 440

1,489

1, 536

1, 584

1, 632

1, 681

1, 463

1, 510

1, 557

1, 604

1, 652

1, 439

1, 485

1, 531

1, 578

1, 625

1, 416

1, 461

1, 506'

1, 552

1, 598

1, 393

1, 438

1, 483

1, 528

1, 573

1, 372

1, 416

1, 460

1, 505

1, 549

1, 352

1, 395

1, 439

1, 483

1, 527

1, 333

1, 375

1, 418

1, 461

1, 505

400

410

420

430 440

A ETA 460

470 480

490

1,730

1, 779

1, 829

1, 879

1, 930

1, 700

1, 749

1,798

1, 847

1, 897

1, 672

1, 720

1,768

1, 816

1, 865

1, 645

1, 692

1, 740

1, 787

1, 835

1, 619

1, 666 1,712

1, 759

1, 806

1, 595

1, 640

1, 686

1, 732

1, 779

1, 571

1, 616

1, 661

1, 707

1, 753

1, 549

1, 593

1, 638

1, 683

1, 728

450

460

470

480

490

510 520

530 540

1, 981

2, 032

2, 084

2, 136

2, 188

1, 947

1, 997

2, 048

2, 099

2, 151

1, 914

1, 964

2, 014

2, 064

2, 115

1, 884

1, 932

1, 981

2, 031

2, 081

1, 854

1, 902

1, 950

1, 999

2, 048

1, 826

1, 873

I, 921

1, 969

2, 017

1, 799

1, 846

1, 893

1, 940

1, 988

1, 774

1, 820

1,866

1, 912

1, 959

oOO

510

520

530

540

SEA 550

560

570

580 590

2, 241

2, 294

2, 348

2, 402

2, 456

2, 203

2, 255

2, 308

2, 381

2, 414

2, 166

2, 217

2, 269

2, 321

2, 373

2, 131

2, 182

2, 233

2, 284

2, 335

2, 097

2, 147

2, 197

2, 248

2, 299

2, 066

2, 115

2, 164

2, 214

2, 264

2, 036

2, 084

2, 133

2, 182

2, 231

2, 007

2, 054

2, 102

2, 150

2, 199

550

560

570 580

590 AAA

610 620

630

640

2, 511

2, 566

2, 621

2, 677

2, 733

2, 467

2, 521

2, 576

2, 631

2, 686

2, 426

2, 479

2, 533

2, 587

2, 641

2, 387

2, 440

2, 492

2, 545

2, 599

2, 350

2, 402

2, 454

2, 506

2, 558

2, 314

2, 365

2, 416

2, 467

2, 519

2, 281

2, 331

2, 381

2, 432

2, 483

2, 248

2, 297

2, 347

2, 397

2, 447

AAA bOO

610 620

630 640 CCA bau

660

670

680

690

2, 789

2, 846

2, 903

2, 961

3, 019

2, 741

2, 797

2, 854

2, 911

2, 968

2, 696

2, 751

2, 806

2, 862

2, 918

2, 652

2, 706

2, 761

2, 815

2, 871

2, 611

2, 665

2, 718

2, 772

2, 826

2, 571

2, 624

2, 677

2, 730

2, 783

2, 534

2, 586

2, 638

2, 690

2, 743

2, 497

2, 548

2, 600

2, 651

2, 703

AfA b50

660

670

680

690 700

710

720

730

740

3, 078

3, 137

3, 196

3, 255

3, 315

3, 025

3, 083

3, 141

3, 199

3, 258

2, 974

3, 031

3, 088

3, 146

3, 204

2, 927

2, 983

3, 039

3, 095

3, 152

2, 881

2, 936

2, 991

3, 047

3, 103

2, 837

2, 891

2, 946

3, 001

3, 056

2, 796

2, 849

2, 903

2, 957

3, 011

2, 756

2, 809

2, 862

2, 915

2, 969

700

710

720

730 740

750

760

770

780

790

3, 376

3, 436

3, 497

3, 559

3, 621

3, 318

3, 377

3, 437

3, 498

3, 558

3, 262

3, 321

3, 380

3, 440

3, 499

3, 210

3, 268

3, 326

3, 384

3, 443

3, 159

3, 216

3, 273

3, 331

3; 389

3, 111

3, 167

3, 224

3, 280

3, 337

3, 066

3, 121

3, 177

3, 232

3, 289

3, 023

3, 078

3, 131

3, 186

3, 242

750

760 770

780

790 800 3, 683 3, 619 3, 559 3, 502 3, 447 3, 395 3, 345 3, 297 800
40 BUREAU OF STA.NDAJJDS

Table 17.Heat content of petroleum vapors in Btu. per gallon of condensed vapor 1

Temp.°F.

1020

32

4050

6070

80

90 100

110 120

130

140 150

160

170

180

190 200

210

220

230 240

250

260

270 280

290 300

310

320

330 340

350

360

370

380 390

400

A. P. I. at i F.

20

0. 9340

1, 371

1, 402

1, 434

1, 466

1, 498

1, 530

1, 563

1, 597

1, 630

1, 664

1, 699

1, 734

1, 769

1, 804

1, 840

1, 876

1,913

1, 950

1, 988

2, 026

2, 064

30 40 50 60 70 80

Specific gravity at 60°/60° F.

0. 8762

1, 208

1, 236

1, 264

1, 293

1, 322

1, 352

1, 382

1, 412

1, 443

1, 474

1, 505

1, 537

1, 569

1, 602

1, 635

1, 668

1, 701

1, 735

1, 769

1, 804

1, 839

1, 874

1, 910

1, 946

1, 982

2, 018

0. 8251

065

090

116

142 169 196 223

250

278 306

335 364

393

422

452

482

513

544

576

607 639

671 704

737

770 804

838

872

907 942

1, 977

0. 7796

941 964

987

1, Oil

I, 035

1, 059

1, 083

1, 108

1, 133

1, 159

1, 185 1,211

1, 238

1, 265

1, 292

1, 319

1, 347

1, 375

1, 404

1, 433

462

491

521

1, 551

1, 582

1, 613

1, 644

1, 676

1, 708

1, 740

1, 772

1, 805

1, 838

1, 871

1, 905

1, 939

0. 7389

834

855 876

901 918

940

962 984

1, 007

1, 030 054

078

102 126

151 176

201 226

252 278

305

332

359 386 414

442

471 500

529

559 589

619

649

680

711 742 774

806

839 872

1, 905

0. 7022

837

856

876

901 918

939

960

981

1, 003

1, 025

048

071 095

118

142

166

191 216

241 266

292 318

344

371 398

425

453

481 509

537 566

595

625 655

685

715 746

777

809 840

1, 872

0.6690

839

858

877

901 917 937

958

979

1, 000

1, 022 044

066

088

111 134

157

181 205 230

254

279

304

330

356

382

409

435

462 490

518

546

574

602

631

651 690

720

750

781 811

1, 842

1 The unit of mass used here, because of its practical usefulness, is the weight of petroleum vapor which, when condensed, is equal to the weight of a gallon of liquid at 60° F. See page 37 for statements regarding the experimental basis for these data and their estimated accuracy. Example—How much heat must be removed in a condenser in order to change vapor at 500° F. into liquid at 80° P., the

gravity of the condensate being 50° A. P. I. at 60° F.? The result is obtained as follows: Heat content of vapor at 500° F. =2,299 Btu./gal. (from Table 17). Heat content of liquid at 80° F. = 146 Btu./gal. (from Table 16). Heat removed=difference =2, 153 Btu./gal,
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 41

Table 17.Heat content of petroleum vapors in Btu. per gallon of condensed vapor—Continued

Degrees A. P. I. at 60° F.

15 20 25 30 35 40 45 50

Temp. F. Temp. ° F.

Specific gravity at 60760° F.

0.9659 0.9340 0.9042 0.8762 0.8498 0.8251 0.8017 0.7796

400

410

420

430

440

2, 088

2, 127

2, 167

2, 207

2, 247

2, 064

2, 102

2, 141

2, 180

2, 220

2, 041

2, 078

2, 116

2, 154

2, 193

2, 018

2, 055

2, 093

2, 130

2, 168

1, 997

2, 033

2, 070

2, 107

2, 144

i; 977

2, 013

2, 049

2, 085

2, 122

1, 958

1, 993

2, 028

2, 064

2, 100

1, 939

1, 974

2, 009

2, 044

2, 079

400

410

420

430

440 450

460

470

480 490

2, 288

2, 329

2, 370

2, 412

2, 454

2, 260

2, 300

2, 340

2, 381

2, 423

2, 232

2, 272 2,312

2, 352

2, 393

2, 207

2, 246

2, 285

2, 324

2, 364

2, 182

2, 220

2, 258

2, 297

2, 336

2, 159

2, 196

2, 234

2, 272

2, 310

2, 136

2, 173

2, 210

2, 248

2, 286

2, 115

2, 151

2, 187

2, 224

2, 262

450

460

470 480

490 500

510

520 530

540

2, 497

2, 540

2, 583

2, 627

2, 671

2, 464

2, 506

2, 549

2, 592

2, 635

2, 434

2, 475

2, 516

2, 558

2, 601

2, 404

2, 445

2, 485

2, 526

2, 568

2, 376

2, 416

2, 456

2, 496

2, 537

2, 349

2, 388

2, 428

2, 468

2, 508

2, 324

2, 362

2, 401

2, 440

2, 479

2, 299

2, 337

2, 375

2, 413

2, 452

50©

510

520

530

540 550

560

570

580

590

2, 715

2, 760

2, 805

2, 851

2, 896

2, 678

2, 722

2, 766

2, 811

2, 856

2, 644

2, 687

2, 730

2, 774

2, 818

2, 610

2, 652

2, 695

2, 738

2, 781

2, 578

2, 620

2, 662

2, 704

2, 746

2, 549

2, 589

2, 630

2, 672

2, 714

2, 519

2, 559

2, 600

2, 640

2, 681

2, 491

2, 530

2, 570

2, 610

2, 651

550

560

570 580

590

600

610

620

630

640

2, 942

2, 989

3, 036

3, 083

3, 131

2, 901

2, 947

2, 993

3, 039

3, 086

2, 862

2, 907

2, 952

2, 998

3, 044

2, 825

2, 869

2, 914

2, 958

3, 003

2, 789

2, 832

2, 876

2, 920

2, 964

2, 756

2, 798

2, 841

2, 884

2, 928

2, 723

2, 765

2, 807

2, 850

2, 892

2, 692

2, 733

2, 774

2, 816

2, 858

600

610

620

630

640 650

660 670

680

690

3, 179

o 997

3, 276

3, 326

3, 375

3, 133

o, lol

3, 229

3, 277

3, 325

3, 090

o, loo

3, 183

3, 230

3, 278

3, 049

o, oyo

3, 141

3, 187

3, 234

3, 009

O, KJD^k 3, 100

3, 145

3, 191

2, 972

O, UIO

3, 061

3, 105

3, 150

2, 935

z, y / o

3; 022

3, 066

3; 111

2, 900

Z, tf^O

2, 986

3, 030

3, 074

650

660

670 680

690 700

710 720

730 740

3, 425

3, 475

3, 526

3, 577

3, 628

3, 374

3, 424

3, 473

3, 523

3, 574

3, 327

3, 375

3, 424

3, 473

3, 522

3, 281

3, 328

3, 376

3, 424

3, 473

3, 237

3, 284

3, 331

3, 378

3, 426

3, 196

3, 242

3, 288

3, 334

3, 381

3, 156

3, 201

3, 247

3, 292

3, 339

3, 118

3, 162

3, 207

3, 252

3, 297

700 710

720

730

740 750

760

770

780

790

3, 680

3, 732

3, 785

3, 838

3, 891

3, 625

3, 676

3, 727

3, 780

3, 832

3, 572

3, 623

3, 673

3, 724

3, 775

3, 522

3, 571

3, 621

3, 671

3, 721

3, 474

3, 522

3, 571

3, 620

3, 670

3, 428

3, 476

3, 524

3, 572

3, 621

3, 385

3, 432

3, 479

3, 526

3, 574

3, 343

3, 389

3, 435

3, 482

3, 529

750 760

770

780

790 800 3, 944 3, 884 3, 827 3, 772 3, 720 3, 670 3, 622 3, 576 800
42 BUREAU OF STANDARDS

3. HEAT CONTENT OF ASPHALT

The data, given in Table 18, on the heat content of asphalts containing vari- ous percentages of mineral matter were calculated from the following equation:

Ha = (0.388£ + 0.000225*2 - 12.65) (1 - 0.01a) + (0.18*+ 0.00003*2 - 5.76) 0.01a

in which £=temperature in °F. and o=per cent, by weight of mineral matter. This

equation was obtained from the integration of equation (5a), using equation (5) for the specific heat of asphalt.

The experimental basis for the data in Table 18 is described in Section VII (4). The tabulated data on heat content of asphalt represent average values which are consistent to about 5 per cent with all of the experimental results at present available, namely, those obtained by the Bureau of Standards and by Zeitfuchs (Ind.

Eng. Chem., 18, p. 79; 1926) on petroleum asphalts and by Dow (Municipal Eng., 21,

p. 22; 1904) on the following refined natural asphalts: Trinidad, Maracaibo, Cuban,

and Burmudez.

The data given in the column marked "0 per cent" are applicable to the bitumen

content of natural asphalts and to petroleum asphalts which usually contain only

small amounts of mineral matter. The data given in the columns marked " 10 per

cent" to "80 per cent," inclusive, are applicable to natural asphalts and to mixtures

of natural or petroleum asphalts with known amounts of mineral matter. In using

these data, it should be noted that the content of mineral matter, as used here,

includes the so-called " free-carbon " content of the asphalt.

The values of heat content given in Table 18 are too small for products containing

water or wax by amounts which vary in proportion to the quantity of these materials

present.

Example.—How much heat is required to raise the temperature of asphalt containing 10 per

cent of mineral matter from 60° to 400° F.? The result may be obtained from Table 18 as follows: Heat content of asphalt at 400° F. = 168 Btu./lb. Heat content of asphalt at 60° F. = ll Btu./lb. Heat required = difference =157 Btu./lb.
THERM AX. PROPERTIES OF PETROLEUM PRODUCTS 43

Table 18.Heat content of asphalt in Btu./lb.

Heat content of asphalts containing to 80 per cent mineral matter, by weight Temp. F. Temp. ° F. 10 20 30 40 50 60 80 — 13 — 12 — 11 — 11 — 10 — 9 — 8 — 7

10 — 9 — 8 — 8 — 7 — 7 — 6 — 6 — 5 10 20 — 5 — 5 — 4 — 4 — 4 — 3 — 3 — 3 20 32 32

40 +3 +3 +3 + 3 + 2 +2 +2 +2 40

50 7 7 6 6 6 5 5 4 50

60 11 11 10 10 9 8 8 6 60

70 16 15 14 13 12 11 10 9 70

80 20 19 18 17 15 14 13 11 80 90 24 23 21 20 19 17 16 13 90 100 28 27 25 24 22 21 19 16 100

110 33 31 29 27 25 24 22 18 110

120 37 35 33 31 29 27 25 20 120 130 42 39 37 35 32 30 28 23 130 140 46 43 41 38 36 33 30 25 150 51 48 45 42 39 36 33 28 150

160 55 52 49 46 43 40 36 30 160

170 60 57 53 50 , 46 43 39 33 170 180 65 61 57 53 50 46 42 35 180 190 69 65 61 57 53 49 45 37 190 200 74 70 66 61 57 53 48 40 200

210 79 74 70 65 61 56 52 42 210

220 84 79 74 69 64 60 55 45 220 230 89 83 78 73 68 63 58 47 230 240 93 88 83 77 72 66 61 50 240 250 98 93 87 81 75 70 64 52 250

260 103 97 91 85 79 73 67 55 260 270 108 102 96 89 83 77 70 58 270

280 114 107 100 94 87 80 74 60 280 290 119 112 105 98 91 84 77 63 290 300 124 117 109 102 95 87 80 65 300

310 129 122 114 106 99 91 83 68 310

320 135 127 119 111 103 95 87 71 320

330 140 132 123 115 107 98 90 73 330

340 145 137 128 120 111 102 94 76 340

350 1101^1 1 49 Loo 1 94 110 1 1 ^ 1UO Q7 350

360 156 147 138 128 119 110 100 82 360

370 162 152 142 133 123 113 104 84 370

380 167 157 147 137 127 117 107 87 380

390 173 163 152 142 131 121 111 90 390

400 179 168 157 146 136 125 114 93 400 420 190 178 167 155 144 133 121 98 420

440 202 189 177 165 153 140 128 104 440

460 213 200 187 174 161 148 135 109 460 480 225 212 198 184 170 156 143 115 480 500 238 223 208 194 179 165 150 121 500
44 BUREAU OF STANDARDS

4. HEAT CONTENT OF PARAFFIN WAX

The data given in Table 19 represent the results of measurements made at the

Bureau of Standards on the summation of three quantities—latent heat of fusion,

specific heat of solid, and specific heat of liquid, all of which are involved simultaneously and inseparably in temperature changes of a complex material like paraffin wax. The data are given in terms of heat content above that of wax at 32° F. The data on the effective heat content of wax, when in solution with petroleum

oils at temperatures below the melting point of the wax, were obtained by extrapolation of the values at temperatures above the melting point. In other words,

the effective heat content when in solution was assumed equal to the heat content

of subcooled liquid and the heat of mixing was assumed equal to zero. The data on heat of solution (or of fusion) were obtained as differences between heat content

of wax and effective heat content when in solution.

The data in Table 19 are consistent, in general, to about 5 per cent, with the

experimental data on the change in heat content of paraffin wax obtained by the

following observers:

Author Eeference

Sullivan, McGill, and French Ind. & Eng. Chem., 19, p. 1040; 1927. Ind. & Eng. Chem., 18, p. 795; 1926. Ind. & Eng. Chem., 12, p. 1197; 1920. Chemische Umschau, Fette, Oele, Wachse, und Harze, p. 71; 1917. Annalen der Physik, 36, p. 413; 1911. Annalen der Physik, 36, p. 67, 1911. " Laboratoriumsbuch fur die Braunkohlenteerindustrie," p. 133; 1908. Atti del reale institute- Veneto, 3, p. 1781; 1884-85. Vierteljahrsschrift der naturforschenden Geselleschaft Zurich, 23, p. 209; 1878.

Fortsch and Whitman

Bushong and Knight

Kozicki and Pilat Nernst Koref—_ Battelli Weber...The estimated accuracy of most of the data in Table 19 is 5 per cent for paraffin waxes obtained from petroleum. The heat content of waxes at temperatures some- what below their melting points may be different by more than this amount for waxes of similar melting points due to different concentrations of the lower melting

point constituents.

Example.—A wax distillate of gravity equivalent to 30° A. P. I. at 60° F. yields 10 per cent by weight, of paraffin wax of melting point 125° F. when cooled to 15° F. How much refrigeration

is required to cool a gallon of this distillate from 90° to 15° F. and crystallize this amount of wax?

The result may be obtained from Tables 12 and 19 as follows: Weight of 1 gallon of 30° A. P. I. distillate =7.30 lbs. Weight of wax = 7.30X0.10 = 0.730 lbs. Weight of remaining oil= 7.30—0.73= 6.57 lbs. Heat content of wax in solution at 90° F. = lll Btu./lb. Heat content of wax at 15° F.= —7 Btu./lb. Change in heat content of wax, 90° to 15° F. = 118 Btu./lb. Mean specific heat of oil (90° to 15° F.) =0.440 Btu./lb. F. Heat removed from oil= 0.440X75X6.57= 217 Btu. Heat removed from wax = 118X0.730 = 86 Btu. Heat removed from oil and wax=303 Btu. per gallon of distillate,
THERMAL PROPERTIES OF PETROLEUM PRODUCTS 45

Table 19.

Heat content and heat of solution of paraffin waxes of melting points 110°, 125°, and

140° F., in Btu./lb.

Heat content of wax

Effective heat content of wax in solution Heat of solution Temp.

°F. Melting point Melting point Melting point Temp.

°F. 110° 125° 140° 110° 125° 140° 110° 125° 140°

5

10

1520

-15

-13

-11

-8

-6

-13

-11

-9

-7

-5

-11

-9

-8

-6

-4

62

656770

j 72

6568

70

73

75

68

7173

76

78

77

78

7878

78

78

79

79

8080

79

80

818282

5

10

1520

25

32

35

4045

-3

+ 14

7

-2

+ 13

6

-2

+ 1 +3

5

75

78

79

8285

78

81828588

8184

8588

91

7878

78

78

78

80

81

818282

83

84

84

8586

2532

3540

45

50

55

60

6570

10

1316

1923

8

1113

1619

7

9

111316

87

90

92

9598

90

93

95

98

101

9396

98

101 104

77

77

76

7675

82

82

828282

86

87

87

8888

50

55

60

6570

75

80

8590

95

27

3238

44

51

2227

3136

42

1922

2529

33

100

103

105 108

111

103

106 108

111 114

107

109

111 114 117

73

7167

6460

8179

77

75

72

88

87

86

8584

7580

85

9095 100

105

110

115

120

60

73

119

121 124

4957

6576

90

38

4349

55

62

113 116

119

121 124

116

119

122

124 127

119

122

125 127

130

534367

62

5748

37

8179

76

7268

100

105 110

115 120 125

130

135 140

145

127

130

132 135 138

130

133 135

138

141

718194

141 144

127

130

132

135 138

130

133

135 138

141

133

136 138

141 144

62

5544

125

130

135

140

145 150

160

170

180 190

141 146

152 157

163

144

149 155

160

166

147

152

158

163

169

141 146

152 157

163

144

149

155 160

166

147

152 158

163 169

n\J o

150

160 170

180

190 200

220

z40

260

280

169

181 193 205 217

172 184

196 208

220

175

187

199

211 223

169

181 193 205 217

172 184

196 208

220

175 187

199 211 223

200

220

240 260

280

300

320

340

360 380

230

243 256

269

282

233 246 259

272

285

236

249

262 275

288

230

243 256

269

282

233 246 259

272 285

236

249

262

275 288

300

320

340

360

380

400 295 298 301 295 298 301 400
46 BUREAU OF STANDARDS

X. CONCLUSION

Many of the thermal properties of petroleum oils appear to vary systematically

with temperature and with the density of the oils. Empirical equations have been

found which represent with moderate accuracy what appear to be the most reliable

experimental data at present available.

Table 20 contains a summary of the empirical equations expressed in engineering

units and also metric units. In the various columns are given (1) the property, (2)

the units in which the property is expressed, (3) the empirical equation, (4) the density

and temperature ranges covered by the experimental data used as a basis for the

equations, and (5) the accuracy of the values given by the equations, estimated

largely from the agreement with the experimental results. The data given in nearly

all of the preceding tables were calculated from these empirical equations.

The present work was undertaken with the object of collecting and correlating

the various scattered experimental data on the subject in order to determine wherein

the existing data were most deficient. The conclusions as to the data on the various

thermal properties may be summarized briefly as follows:

Thermal expansion.—The data given in Tables 1 to 5 supplement similar data

given in Bureau of Standards Circular No. 154, National Standard Petroleum Oil

Tables. The information now available on thermal expansion appears sufficient to meet most of the requirements of industry. Additional experimental data at high

temperatures appear desirable.

Heat of combustion.—The data given in Tables 6, 7, and 8 appear to be sufficient

for all practical uses of such data. Heating value determinations on petroleum

products as routine tests seem to serve no useful purpose.

Specific volume of vapor.—The data given in Table 9 for products of gravity 50°

to 150° A. P. I. appear to be sufficiently reliable for most industrial purposes. The

data given for products of gravity 20° to 50° A. P. I. are admittedly approximate and

are included mainly for the benefit of those users of petroleum products who have no

information at hand as to the source or the volatility of these products. Additional

experimental data on molecular weights of products of gravity 10° to 40° A. P. I. appear desirable.

Thermal conductivity.—The data given in Table 10 appear to be sufficient for all practical uses of such data.

Specific heat.—The data given in Tables 12 and 13 appear to be sufficiently

reliable for all practical applications wherein only moderate pressures (less than 50

lbs. /in.2

) are involved. Additional experimental data on petroleum vapors and also on petroleum liquids at high temperatures and pressures are desirable. Latent heat of vaporization.—The data given in Table 15 are in general accord

with the available, somewhat fragmentary, experimental data, the reliability of

which appears uncertain. Additional experimental data, particularly at pressures

above 1 atmosphere, are desirable.

Heat content.—The data given in Tables 16 to 19 should provide simplicity and

convenience in calculations of the quantities of heat involved in the heating and

cooling of petroleum products.
THERMAL PROPERTIES OF PETROLEUM PRODUCTS

Table 20.

Empirical equations for thermal properties of petroleum products

47

Experimental range Esti- mated

Property Units Empirical equation

d t

accuracy, per

cent

In engineering units: d=specific gravity at 60°/60° F.; *= temperature in °F.; p=pressure in lbs./in. 2 absolute; unit volume

of liquid =gallon, measured at 60° F.

Coefficient of expansion of liquid.

1 dV =A+2B(t-G0)~- - 0.51-1.00 32-200 5

Vio dt

log(AX105) =0.835+—°; log(.BX103) =^°-1.20

Total heat of combustion at fBtu./lb = 22,320-3,780^... }o. 51-0. 99 constant volume. \Btu./gal = 186,087d-31,515d3

1 Specific volume of vapor Thermal conductivity of

ft.Vlb =0.242(*+460) (1.03-d)

0. 51-0. 80 10 Btu. in. p d

[1-0.0003(^-32)] 0. 78-0. 95 32-400 10

liquid. ft.2 hr. °F.

jBtu./lb. °F..._ =-j= (0.388+0.00045<) _.

Jo. 72-0. 96 32-750 5 V d

i Btu./gal. °F...

fBtu./lb „

' = V d (3.235+0.00375*) _ Latent heat of vaporization.

=-^-(110.9-0.09*) —

J-0. 64-0. 91 100-600 10 [Btu./gal =925-0.75* Heat content of liquid Btu./gal = V d (3.235*+0.001875*2-105.5) 0. 72-0. 96 32-750 5 Heat content of vapor Btu./gal = V d (3.235*+0.001875*2-105.5)+925-0.75* 0. 64-0. 91 100-600 5

In metric units: d = density in g/ml at 15° C; <= temperature in °C; p=pressure in atmospheres; unit volume of liquid

milliliter, measured at 15° C.

0. 51-1. 00

•0. 51-0. 99

0-100 5

1

0. 51-0. 80 10

0. 78-0. 95 0-200 10

•0. 72-0. 96 0-400 5

0. 64-0. 91 40-300 10

0. 72-0. 96 0-400 5

0. 64-0. 91 40-300 5

Coefficient of expansion of

liquid.

Total heat of combustion at constant volume.

Specific volume of vapor

Thermal conductivity of

liquid.

Specific heat of liquid.

Latent heat of vaporization. Heat content of liquid. Heat content of vapor.

1 dV

Vn dtCal./g... Cal./ml.

1/g-Cal. cm. cm 2 sec. °C

Cal./g °C...

Cal./ml °C_.

Cal./g Cal./ml

Cal./ml

Cal./ml

=A+2B(t-15)... logUXlO5) = 1. 09+°^; \og(BXm =^°-0.£ = 12,400-2,100^2 = 12,400<i-2,100d3 _ 0.821 (*+273) _ (1.03-d) =»1 _ _ 0C054f] d___ = -=(0.403+0.00081*) V d = Vd (0.403+0.00081*) (60-0.09*) =60-0.09* = V~d (0.403i+0.000405*2) .... =60+(0.403 V d -0.09)*+0.000405 V d *

2

It is fully realized that the experimental data on several of the above properties is not as complete as could be desired and that a revision of the tabulated data may be

rendered necessary by additional experimental work, such as that recently undertaken on ''The Thermodynamic Properties of Petroleum Hydrocarbons/' listed as project No. 38 of the American Petroleum Institute Research. Hence, the tables

here presented are not to be considered as final, but as best representing our present

knowledge.

This publication represents the first attempt apparently ever made to supply the

petroleum industry and the users of petroleum products with comprehensive data on the thermal properties of these products in readily useful form somewhat analogous

to the tables now available on steam and ammonia. This is indeed surprising

when it is recalled that heat is involved, almost without exception, in all of the numerous processes used to convert crude petroleum into its many useful products.

Tables of the properties of steam and ammonia, based largely on the extensive

researches of Regnault, were available to mechanical and refrigerating engineers
48 BUREAU OF STANDARDS

nearly 50 years ago. Those tables played no small part in the progress and development of these two branches of engineering. The importance of such tables in engineering is reflected by the elaborate researches conducted on steam and ammonia in recent years, primarily to extend the range and accuracy of the tabulated data.

The petroleum industry has been less fortunate. It has had no analogous tables

to point the way toward advancement in processes and in design of equipment.

If the petroleum industry, in the last 25 years of its astounding growth, had possessed

as much information on the thermal properties of its fluids as was made available on

steam and ammonia by Regnault in 1862, the economic saving in more efficient methods and apparatus would probably have amounted to an appreciable fraction

of the total value of its products.

ACKNOWLEDGMENT

This paper contains the results of a critical survey of existing data which was undertaken as a preliminary step in an investigation on "The Thermodynamic Properties

of Petroleum Hydrocarbons," fisted as project No. 38 of the American Petroleum

Institute Research. Financial assistance in this work has been received from a

research fund of the American Petroleum Institute donated by John D. Rockefeller.

This fund is being administered by the institute with the cooperation of the Central

Petroleum Committee of the National Research Council.

Washington, April 20, 1929.

o