NATIONAL BUREAU OF STANDARDS REPORT

2942

Progress Report

on

Air Conditioning in Underground Structures

to

Office of the Chief of Engineers

Department of the Army

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards is suggested in the following listing of

the divisions and sections engaged in technical work. In general, each section is engaged in specialized research, development, and engineering in the field indicated by its title. A brief description

of the activities, and of the resultant reports and publications, appears on the inside of the back

cover of this report.

Electricity. Resistance Measurements. Inductance and Capacitance. Electrical Instruments. Magnetic Measurements. Applied Electricity. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology. Length. Gage.

Heat and Power. Temperature Measurements. Thermodynamics. Cryogenics. Engines and

Lubrication. Engine Fuels. Cryogenic Engineering.

Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid State

Physics. Electron Physics. Atomic Physics. Neutron Measurements. Infrared Spectroscopy.

Nuclear Physics. Radioactivity. X-Rays. Betatron. Nucleonic Instrumentation. Radiological Equipment. Atomic Energy Commission Instruments Branch.

Chemistry. Organic Coatings. Surface Cheipistry. Organic Chemistry. Analytical Chemistry.

Inorganic Chemistry. Electrodeposition. Gas Chemistry. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics. Sound. Mechanical Instruments. Aerodynamics. Engineering Mechanics. Hydraulics. Mass. Capacity, Density, and Fluid Meters. Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Polymer Structure. Organic Plastics. Dental Research.

Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion.

Mineral Products. Porcelain and Pottery. Glass. Refractories. Enameled Metals. Concreting Materials. Constitution and Microstructure. Chemistry of Mineral Products.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Floor, Roof, and Wall Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Machine

Development.

Electronics. Engineering Electronics. Electron Tubes. Electronic Computers. Electronic

Instrumentation.

Radio Propagation. Upper Atmosphere Research. Ionospheric Research. Regular Propagation Services. Frequency Utilization Research. Tropospheric Propagation Research. High

Frequency Standards. Microwave Standards.

Ordnance Development. These three divisions are engaged in a broad program of research

Electromechanical Ordnance, and development in advanced ordnance. Activities include

Ordnance Electronics. basic and applied research, engineering, pilot production, field testing, and evaluation of a wide variety of ordnance materiel. Special skills and facilities of other

NBS divisions also contribute to this program. The activity is sponsored by the Department of

Defense.

Missile Development. Missile research and development: engineering, dynamics, intelligence,

instrumentation, evaluation. Combustion in jet engines. These activities are sponsored by the

Department of Defense. • Office of Basic Instrumentation • Office of Weights and Measures.
NATIONAL BUREAU OF STANDARDS REPORT

Air Conditioning in Underground Structures

hy

S= A „ Peavy

Ho E„ Robinson

Eo So Dill

to

Office of the Chief of Engineers

Department of the Array

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

MBS PR@JE©T

1003-10^4831

NBS REPORT

November 27, 1953 2942

Progress Heport

on

The publication, ri

unless permission i 25.D.C. Suchp®

tally prepared If I

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 201 5.

1 In part, Is prohibited

tandards, Washington

sport has been spedfleport fer Its own os«.

PROGEESS REPORT

AIR CONDITIONING IN UNDERGROUND STRUCTURES

I . INTRODUCTION

During the period from May 1 to November 15, 1953 » tests have been

continued in the underground test chamber at Mount Weather, testing at

the fort Ritchie site was initiated, and tests were made on the tunnel

ventilation and underground spray pond projects at Mount Weather, Va„

Data from previous tests were analyzed and two reports are included, one on an initial warm-up period and the other on tunnel ventilation,, Also

included are the method for determining thermal conductivity of rock

core samples, a theoretical heat transfer study of the vehicular tunnel

and underground reservoir at the Port Ritchie site, a trip to other

underground sites, and a mathematical treatise on the region bounded

internally by a circular cylinder.

II. TESTS PERFORMED AT MT„ WEATHER, VA.

1 . Underground Chamber

Test condition 12 - Steady state heating at 75® F air temperature from February 11 to April 13 , 1953°

No dehumidification or ventilation air.

Test condition 13 - Steady state heating at 75® F air temperature with ventilation air from April 14 to May 7 , 1953°

Test condition 14 - Cooling of chamber with negligible heat

added and no ventilation air or dehumidification from May 8

to May 27, 195 3

.

The remainder of the report period was spent with intermittent

ref rigeration of the chamber air in order to reduce the temperature in

the rock to approximately the original temperature of 53® F.

2. Underground Spray Pond Heat Exchanger

Test condition 1 - A constant heat input rate of approximately

55,000 BTU/hr was added to the spray water until the temperature

of the pond water reached 100® F - May 18 to June 7 , 1953°

Test condition 2 - The temperature of the spray water was maintained at approximately 100° F until there was perceptible

temperature rise at the 20-foot rock depth.

- 1-
-
The remainder of the report period was spent with refrigeration of

the pond water in order to reduce the temperature in the rock approximately to the original temperature of 53° D* During the next reporting period,

test conditions 3 and 4 will he run which are a repeat of conditions 1 and 2 except recirculation will he made to a stagnant pond instead of

using sprays

.

3o Tunnel Ventilation

Test condition 1 - Summer ventilation air was induced through the

l400=foot tunnel at an average air-flow rat© of 24,700 cfm for the

period July 8 to July 20, 1953° Temperatures and relative humidity

were recorded for the air entering and leaving the tunnel

*

Kb more tests were made during this reporting period because of

Bureau of Mines activity in the main tunnel„ During the next reporting

period, tests will he made using winter ventilation air*

III. TEMPERATURE STUDIES AT SITE HEAR JT* RITCHIE, MB*

lo Ve ntilation shaft

Thermocouples were placed at selected positions in the east

ventilation shaft and temperatures are measured by them in conjunction

with a recording potentiometer located at the bottom of the shaft*

The intended operation is that the east ventilation shaft will be used

every other week* Recordings will be made of the air and rock temperatures currently during use of the east ventilation shaft*

2. Structure

Thermocouples were placed at selected positions in the rock, rock

surface, ventilation air stream to structure and exhaust air stream

from the structure* Temperatures are measured by the thermocouples in

conjunction with a portable precision potentiometer* Readings of these

temperatures are being made on a bi-weekly basis due to the very limited

occupancy of the structure*

3* Cooling Water Heat Exchange to Earth

Temperature sensitive instruments have been ordered for installation in the 8-inch cooling water pipe* Temperatures will be measured

at the cooling tower bypass and on the feed and return lines at the

portal, blast gate, and power room*
•

'

!j

j

1

I
IV. INITIAL WARM-UP PERIOD OP UNDERGROUND CHAMBER

MTo WEATHER, VIRGINIA - April 23 to May 15, 1953

Object

The object of this test was to determine the time needed to bring

the temperature of an underground chamber up to a temperature comfortable

for human occupancy by means of a constant heat input rate, and also to

determine the applicability of the theoretical equations of heat transfer

to the experimental data gathered.

Description of Underground Chamber and Equipment

The underground chamber, the dimensions of which are 100” x 35' x 10*

high, is adjacent to and connected with an experimental mine operated by

the Bureau of Mines at Mount Weather, Virginia, The chamber is approximately 215 feet below the surface of the ground and 1,200 feet from the

surface in a horizontal direction. The rock mass bounding the chamber

consists mainly of greenstone with a scattering of epidote and quartz,

and. traces of various other minerals. Petrographically , the greenstone

is a metamorphic basalt partially colored green by the presence of

chlorite.

Measurements of the surface area of the walls, floor, and ceiling

were made and showed that the projected surface area was approximately

10,000 square feet. Physical determinations of greenstone rock from the

excavation were made at this Bureau and the results were;

Density, p = 186 lb/ft^

Specific heat, c = 0.2 BTU/ib ®F

Thermal conductivity (cores) k - 1.45 BTU/hr ft ®F

Thermal diffusivity, s 0.039 ft^/hr

The apparent porosity of greenstone samples tested by the Bureau of

Mines was 0.50 percent.

The walls and ceiling are painted white and the floor paved with concrete. Figure 1 shows plan and elevation views of the chamber and arrangement of mechanical equipment and air distribution ductwork. Air was forced

by the circulating fan (l) into the ductwork past electric strip heaters

(5) to the diffusers (6) and the air from the chamber was returned to the

circulating fan through the air return filters (?) and the plenum chamber.

Fifteen 12-foot long thermocouple poles were placed at selected

positions (figure 2) in the rock. Thermocouples had been previously attached to these poles at intervals—one-half-foot intervals up to 6 feet

and one-foot intervals from 6 to 12 feet. Room air temperatures were measured at heights of 2, 3^» 60, and 90 inches above the floor at twenty

stations in the chamber. The thermocouples were copper-eonstantan and

temperatures were measured by them in conjunction with an indicating

potentiometer located in an instrument room built within the chamber.

“ 3=
. * ' II*I.I1I1 - I
Theory

For analytical purposes, the heat transfer in the test chamber was compared with that occurring in three elementary geometric shapes; namely, a cylinder, a sphere, and a group of plane surfaces., The boundary con- ditions were that heat was transferred to a solid bounding an elementary

shape with a constant heat flux at the surface of the shape and the

initial temperature of the solid was assumed equal to zero as an arbitrary

datum plane. For the three cases under consideration, the temperature at a distance from the surface is

;

plane

cylinder

V = |

^ct" (2 ierfc

v = Sf1

) ' Jx% I 2 ierfc ~Ji - i 2erfc

K \r / L 2v£ct 8ar

4, ^ t(53r2

t. . 6ar + 9&2

) ± ^erfc r - a

~|

sphe re v -_ ft a*

Kr

loa2r

2 * 2 \[ocl

r - a +«c t erfc — - a erfc r - a

2 V&C.t

and the temperature at the surface of the solid is?

plane

2 vGct

n

v = 1,1284 | fz%

cylinder

sphere

V s 9a

K

2 foe t\

FrfW)

1/2

1 < t 2 +

2 \Fff \ a2

y

1

^'3/2

16 i. a

* tb - *Kt,a' ertcM_

( 1 )

r - a

2 VSct

( 2 )

(3)

(4)

(5)

( 6 )

where the equations for the cylinder are applicable for small values of

time (satisfactory for the duration of the test in question). Development

of the above equation can be found in "Conduction of Heat in Solids", by

Carslaw and Jaeger, Oxford Press, 1948,

Homenelature and Units

v = temperature above arbitrary datum plane, ®F,

Q, = constant heat flux at surface of solid, BTU/hr ft^,

t = time, hours,

<x - thermal diffusivity of solid, ft2 /hr„ x distance into solid from plane surface, ft, a = radius of cylinder on sphere, ft,

r = radius of concentric cylinder or sphere composed of solid

for r greater than a, ft,

K = thermal conductivity of solid, BTU/hr ft deg F„

erfc y is the complement of the error integral and ierfc y, i^erfe y

and i.3erfe are successive integrations of erfc y.

-4-

Test Procedure

With the initial temperature in the rock to 12 feet in depth

practically uniform at 53*0 ® F„ a constant heat input of 17=8

kilowatt or 60,800 BTU/hr was supplied to the test chamber „ At regu=

lar intervals during the test, temperatures of the rock surface, the

rock at selected depths , room air, wet and dry bulb of the room were recorded as well as the electric energy input as measured by kilowatthour meters

o

The test was arbitrarily terminated at the time when the average

of the plane rock surface temperatures at poles 1 , 2 , 3 , 5 , 9 , 11 , and 15 on figure 2 reached ?0 ® F» This time was 522 hours or 21*75

days „

Results

Figure 3 is a plot of the average rock temperature (computed from

the average of the tenroeratures on the fifteen poles) against depth

in the rock, with time as a parameter* Figures 4 to 8 show temperature

distributions at various cross sections in the rock after 521 hours

of test*

Following is a table showing the heat input to the chamber from

readings of watt hour meters compared with the heat stored in the rock

computed from the mean temperature rise at various times from the start

of the test* Also the depth of perceptible heat penetration is noted*

8 Time “

« Electric heat input

8 9

8 Heat in rock4 8

8 8 Heat penetration

hr 0 49 8

i

BTU

3,010,300

« BTU »

8 2 , 979,300 8

9 s

ft

5*0

oo 5,960,000 8 6,299,000 8

9 8 7.8

170 0

8 10,256,000 8 11 , 243,000 8

1 1 8*8

290 8

0 17,928,000 8 18,581,000 8

0 8 11*0

*Uo attempt was made to account for irregularity in heat flow

at compressor room and chamber entrance in computing heat

absorbed by rock* The mean tenperature was determined by

finding area under curves of figure 3 s> and dividing the

area by the depth of perceptible heat penetration* The

specific heat of the rock was 37»2 BTU/ft^®F*

“5

“

The average room air temperature was approximately 6° F above that

of the rock surface temperature throughout the test and the heat flux

calculated from the kilowatt-hour meter readings averaged 6.08 BTU/hr ft2 . From these data, the heat transfer from the room air to the rock surface

appeared to obey Newton's law of cooling;

Q, = h2iT (7)

where the surface conductance coefficient h was approximately

l o 0 BTU/hr ft2 °Fo

Beferring to equations (4), (5), and (6), the heat flux, Q,, was computed from the experimental surface temperature data corresponding to

various times after the start of the test and plotted on figure 9° The

equivalent radii for the cylinder and sphere were computed on the basis

of surface areas equal to that of the space, yielding radii of 15»9 ft

for the cylinder and 28,2 ft for the sphere. The values of heat flux

computed from equations (4), (5), and (6) were used in computing the

temperatures at 0 o 5~» 1»0=, 2„0~, 3‘>0“» and 4,0-foot depths in the rock

by equations (l), (2), and (3)= These temperatures are plotted on figure 10 along with the experimental values for comparison purposes.

Figures 11 and 12 show views of the underground chamber.

Discussion and Conclusions

1, The heat balance showed that the heat stored in the rock as com- puted from the observed temperatures of th© rock agreed with the

measured electrical heat input to within 10 percent,. This com- parison was made for the first 290 hours of the test because the

heat penetration exceeded 12 feet soon after that time.

The computed heat input was greater than the measured heat input,

which seems to show that the average temperature® computed from

temperatures in the rock from the fifteen poles were higher than

the actual average temperatures in the rock,

2, Figures 4 through 8 show isotherms in the rock at various cross

sections. The isotherms tend to elliptical shape, especially

in smaller cross sections and at greater depths,

3, The coefficient of heat transfer between the air and rock surface was approximately 1,0 BTU/hr ft2 deg F, This value is

approximately what would be expected for this case wherein heat

transfer was by natural convection from nearly still air, with

negligible radiation because all surfaces were approximately the same temperature.

-6-
s

'

-

.
4. The constant rate of energy input to the chamber, as measured

electrically averaged 60,800 BTTJ/hr, which gives an average heat

flux of 6,08 BTU/hr fi^ for the measured 10,000 square feet of

projected surface area. The discrepancy between the measured

and calculated heat flux (figure 9 ) is believed to be due

primarily to the difference between the actual shape of the

chamber and the shapes assumed for mathematical analysis; namely,

that heat flow from the chamber surfaces took place in three

dimensions (diverging similar to radii of a sphere) whereas the

equations apply strictly to one-dimensional flow for the plane

surface, two-dimensional flow for the cylinder equation, or three-dimensional flow for the sphere equation. The difference

between the measured input flux and that calculated from the

plane and cylinder equations is considered due to the extra bulk

of rock beyond corners and edges and that from the sphere equation is considered due mainly to the difference between the

configuration of the chamber and a sphere. Other sources of error

that may help to explain the discrepancy of the measured and com- puted values are air leaks, heated water migration from drips into

the chamber via the aggregate and concrete floor to the tunnel

outside, water vapor migration to the tunnel outside and heat

transfer through walls at chamber entrance and compressor room.

5» In order to determine the applicability of the theoretical

equations of heat transfer to the experimental data, the measured

rock surface temperatures were used in equations (4), ( 5 ), and

(6), and resultant values of heat flux were plotted on figure 9=

For the 522 hours of testing, the computed values decreased almost linearly with time. Percentage decreases in 522 hours are;

plane, 14 percent; cylinder, 9»1 percent, and sphere, y percent.

Since the actual heat flux, was constant within ±2 percent, the

change in heat flux indicated by equations (4), ( 5 ), and (6) for

planes, cylinders, and spheres of equal surface area indicate the

degree to which these simple geometric shapes cannot be used to

accurately predict heat flow in a chamber of another shape.

Equations (4), (5), and (6) are theoretically based on constant

heat flux to the surface of the solid from which heat flows into

the solid whose volume at a given distance from the surface is

known, A comparison is given in the following table showing the

volume of solid surrounding the actual chamber and that of the

three geometric shapes at various depths.

“7

-

Volume of rock 'between the surface and, various depths, eu ft

Chamber shape

0

9

9

«

Depth below surface, ft

1 2 3 4 6 10

Actual chamber

I

9

0 10,465 21,876 3^258 47,637 77 M5 150,240

Sphere

;

1 Radius = 28»2 9 0

II 10,351 21,438 33.283 45,912 73,622 139,570

Cylinders 1 Radius = 15 • 9

8 9

9 10 , 304 21,237 32,798 44,990 71,251 131,320

Plane 9

I 10,000 20,000 30,000 40,000 60,000 100,000

The table shows that the volumes of rock in the sphere, cylinder,

ana plane diverge from the actual volume with increase in deptho The

sphere is the closest approximation to the actual volume. The divergence between the amount of rock being heated in the actual chamber

and that which would be heated for the plane surface, cylindrical,

and spherical cases for measuring depths probably explains why the

computed heat flux decreased with time as shown in figure 9°

6» Figure 10 shows the temperatures in the rock at 0o5 =

, l-» 2-, V»

and 4-foot depths and the temperatures computed from equations (l),

(2), and (3

)

> 4s was noted in the results, values of the heat flux were picked from figure 9 in order to determine the temperature in

the rock at any given time. This seems to adjust the temperatures

in the rock to allow for the increase in volume of the actual over

the volumes represented by the plane, cylinder, and gpher@„ The

computed values give fair agreement to the experimental values,

especially at the 2~, 3~9 and 4-foot depths

„

“8-
.

.

.

-
Fig

I



70

68

66

64

u.62

»

©a

|60

58

56

54

52

2 4 6 8 10 12

Depth in feet

1

NBS



FIG- 5

SECTION B-B

SCALE • y

« I'-O*

TEST CONDITION No. I- HEATING UP PHASE

TEMPERATURE DISTRIBUTION IN ROCK

AFTER 521 HOURS

B



5

12 '

II



14

NBS

<£> '

i—t- - 2



ELECTRICAL

AND

COMPUTED

HEAT

FLUX

.

TEST

CONDITION

:=H+P

xnu IV 3 H

t?T B±J pr

1

IOO

200

300

400

500

600

700

TIME

IN

HOURS

FIG.

9

z

uj30G

500

TEMPERATURE^E at rock depth

TEST CONDITION

CONSTANT HEAT INPUT

INITIAL TEMPERATURE^ 53°F

400

XP6RIMENTAI

TEMPERATURE DIFFERENCE (*,-53.0),*F

Tin, in

- -

/Vj>

4

r <

YLi





V, TUNNEL COOLING OF VENTILATION AIR

Object

The object of this test was to determine the temperature drop and

heat loss of ventilation air in an underground tunnel during summer con- ditions at Mount Weather, Virginia, and to obtain data that would help

to predict what might be expected in other tunnels used for ventilation

of underground spaces.

Description of Underground Tunnel and Equipment

The underground tunnel (figure l) was approximately 1,400 feet long

with nominal dimensions of seven by seven feet. At the end of the tunnel

was a 230-foot shaft (at L5 on figure l) upward to the surface „ Air was

drawn through the tunnel from its entrance at the surface and up the

shaft by a centrifugal blower mounted over the shaft . Canvas barrier®

were placed across the tunnels RX and R2-1 for the test as shown in

figure 1 to prevent appreciable by-passing of the main tunnel,

Hygro thermo graphs were placed at the tunnel entrance and at the end

of the tunnel at L5 to measure dry-bulb temperature and relative humidity.

Three times daily, temperature readings of the air, rock, and flowing water

were taken at various cross sections (l~13 on figure l) in the tunnel.

Other readings were air-flow rate, static pressure drop across the blower,

and pressure drop in a selected 100-foot section of tunnel.

Results

An average air-flow rate of 24,700 cubic feet per minute was maintained in the tunnel for a period of ten days for which the last five days

are analyzed in this report.

Figure 2 shows the outside air conditions for the period July 14-18

and the average daily dry-bulb temperature and humidity computed from the areas under the curves. For this period, the temperature at the end of

the tunnel at L5» was nearly constant at 59® F and 100 percent relative

humidity. Table 1 shows the average daily heat and moisture release of

the ventilation air, as well as the heat loss rate per foot of tunnel

and temperature difference between the entering air and leaving air.

Figure 3 shows the air temperatures at the numerically designated

cross sections of the tunnel for times O63O, 12-30, and I7OO of July 15

.

Tables 2 and 3 show the air, rock surface, and water temperatures at the

thirteen stations and the rate of heat loss of the air per foot of tunnel

between the stations for the times 1700 and Q63O of July 15, respectively.

“

9=
i: ..'’.arri; imb'x

'

arid' ; s

iBsxcatf 5.-! Pool t

• >

-

• '. 5 .;

. ed$ o £' v^Pirtexs

X 3xixi. .

•" ' 'ii rool i

•P ifV 0T SiiS 4 - XiT:

•P
The coefficient of heat transfer “between the air and the rock

surface was computed for the time XyOO July 15 and for the distances

between the entrance and the various stations up to 1,200 feet from

the entrance by the relationship

h - T~%Z A Atm

where h = coefficient of heat transfer between the air and rock surface

BTU/hr ft2 deg F

A - projected surface area of tunnel, ft2

£t m - logarithmic mean temperature difference of air and rock

surface, deg F

Q, = heat transfer rate to surface A, BTU/hr

The average value for these computations was BTU/hr ft£' deg J,

The static pressure drop across the blower was 3°5 inches of water

and the pressure drop in the selected 100-foot section of tunnel (between

stations 11 and 12) was O.Oh inches of water.

Discussion and Conclusions

1. Table 1 shows that average heat loss rates up to 932,000 BTU/hr can

be accomplished by this tunnel. No conclusions can be made at this

time as to whether this rate could be sustained over a long duration

of average outside air conditions of 82 deg F and 58 percent relative humidity o It is hoped that a test can be made during a greater

portion of the 195^ summer season to determine more conclusively the

effectiveness of the rock surrounding the tunnel as a. heat sink for

an extended period of time. Also, it is suspected that additional

benefit will accrue from the seasonal changes, e.g., the rock will

act as a heat sink in the winter and a heat source in the summer.

2. Table 2 show® that more than half of the heat lost from the air was

lost in the first 200 feet of tunnel. This was a ca.se of sensible

cooling of the sir with possible evaporation of moisture from the

tunnel walls. Drying of the tunnel walls up to R1 was observed. A

case of the combination ©f both sensible and latent cooling is shown

in table 3 where less than 20 percent of the heat was taken from the

air in the first 200 feet. This condition will not always be true,

but serves to show that where air temperatures in the tunnel go

below the entering air dew-point temperature, more of the tunnel

area can be utilized as a heat sink by dissipating the latent heat

of condensation.

3° Air flowing by diffusion or force through side passages added to the

effective area for heat transfer. This was evident by observation

of air flow around the edges of the canvas barriers placed in HI

- 10-
.

.
and B2-1 and by table 2 0 where the heat loss between . and 7 increased over the two preceding 4, atlQns ^

Water

drop was

flow

greater

from

but actually the airflow rati wafs^eT^®

main tunnel

the side passage R1 was more than tha+ in the above Hi and wag al«?n

" na " n the

3, comparing water 2 “d

The average coefficient of best transfer between , and the rock: surface, when the heat transfer was for all nrart? i t0 u 4 ” 73

Engineers°^1953

A“ric“ Soci«V of Hea?^6^^^!^146 "

'

the test “ !fhe averag© coefficient of heat traLfb^wh^T

re r— z:

When only sensible cooling of the air . * tunnel;, the unit heat loss in BTU/hr (ft of ftT«5Sing

ventilation

in the 1,400

rate

feet

of

of

24

tuzmll)

700 c 3f m m

Lie

v a

t

'J'f^

19 for an^

air

removal of moisture fril the airand wl “°Ula indic“*

an increase in ^^l.^V'TSr ^ ££ TuV^

i7 rTM J tZ Z' stream and that for 4 It Zt Ld ^ T*”6 of the

air stream. These cha^^£^£-

column^ Stable T “*rtlT' TMluea °f mol9tare !<>•• shown in

seems to show that within a restri^o^ ,

“ ^nal ° Thls P lot

aAT S ea+bX

where AT s temperature difference

x s distance in tunnel from entrance

e s base for natural logarithms

a,b s constants

Determinations of the constants a and b were made but .m * held in abeyance until further .ubstantA^Tta £.* X-d,

“11-
'

..

.

I

j

I

1
Table 1. Average daily heat and moisture loss of tunnel ventilation air

Average air flow 24 , 7^0 cfm "based on 59® F and 100 percent

relative humidity at end of tunnel

Date

Outside air conditions

I !

1 1 (Moisture,

j loss g

1 1

Heat loss

' Dry-hulls

a temperature

( Relative

t humidity

9

, Dew

, point BTTJ/hr

' Tons 1 ’refrig- 1

1 ©ration'

BTU

hr-ft-M?*

7/14/53

* oy

• 72 = 9

i

8 Percent

• 58 = 7

1

1 op

8 57*5

i

1 Ih/hr 1

8 "75 8

1 1 320,000

t 1

8 26=6 8

« 1 16.4

7/15/53 • ?6 o 0

1

8 61 = 0

t

9 6l = 5

j

8 +107 ' 8

t 1 640,000 0 5^ 0 2

9

! "S 26 = 9

7/16/53 ' 79 o0

8

' 54 = 6

1

8 61 = 2

1

8 84 8

1 1 696,000 vn 00 0 24 = 8

7/17/53 8 80 o9

1

' 52 = 4

1

1 61.8

1

1 118 8

1 1 786,000 8 65=4 8

1 1 25.6

7/18/53 • 81 = 9

1

8 55 = 7

8

8 64=5

1

8 252 8

8 1 932,000 8 77 *7

8

1 1 29 = 1

* A T = temperature difference "between temperature of entering air and

air at L5 °

- 12-

I

Table 2» Temperatures at stations and lineal heat

loss Taetween stations - 1700 July 15, 1951

Station

No o1

2

3

4

5

6

7

8

9

10

11

12

13

si i ?

1 Distance '

' in tunnel

8 t

1 8

Air temperature

' Heat loss (sensible)

BTU/hr ft tunnel

11

8

( Average

surface 8

( temperature

8

' Water

s tempers.

* ture

8

1 ft 8 op 11 0 op 8 ®p

8 0

8

8 0 85 „0 8

8 1,752

8 ___ ! 58.3

8

8 50 '

8 I 82 „ 2

!

!

1 2,960

' 66„2

!

! 57.6

8 oo

11— 7608 8

1 2,020

' 67.5

8

9 5? 0 2

8

0 150 8

8 8 73*0

1

1

1 674

' 62,9

8

1 56.7

6

t 200 *

1 D 7 I 08 8

' 505

• 6lo9

1

5 56.2

8 oO 7O 0 I

!

1 898

0 60 o 0

8

' 55 .4

8

8 400 0

1 6 6608 11 618

1 60 „ 7

0

8 58.4

1

1 600 «

i g 62 „ 3

1

8 06

° 60 o 0

8

' 58o 3

8

8 800 1 6lc6 0

' 59 o 4 ' 58.3

t i

« 204 8 8 o oo

18— 60.1 0

8 123

1 59 °2

8

‘ 57.3

8

8 lt 200 1

1 0 59 »2 0

8

1 57°9

0

' 56.9

9 H oo 59° 3

8

8 ==_

8 57 o 6

8

1 56.6

8 O O

i

—

1

59-1 1

« 57 „ 1 ' 56.7

8 8

tic

Oo

1

2

3

4

5

6

7

8

9

10

11

12

Table 3® Temperature at stations and lineal heat lose

•between stations - 0630 July 15, 1953

i

' Distance

in tunnel

»

Air temperature

8 Heat loss BTU/h.r ft 1 Average

» of tunnel « surface

9 " ~~ ”7 TM~

« temper-

, Sensible# Latent

( ature

«

i Water

i temper-

, ature

ft 9 ®F ®]T ! ©J>

9 0

1

I 9

« 50 8

I 9

« 100 1

« 8

8 x5 o

«

1 8

8 200 8

! 9

8 300 i

I 9

8 400 8

i i

8 600 8

1 8

9 800 8

8 I

9 1,000 8

I I

8 1,200 8

0 8

« i s 3oo »

1 D

9 1,400 1

t i

65 .2 8

8 64o5 6

9 64„l 8

0 63 o 2

9

1 62.7 8

« 62.1 9

1 61.0 8

1 60.0 8

« 59®4 8

8 59 ol 8

9 58.6 9

» 58.4 8

8 58.7 8

9

449

180

494

270

146

281

124

84

39

67

9

8

8

8

67

562

258

141

79

123

90

i ___

8

9

8 58.0

• 60.7

1

8

1 57.9

8 60.3

1

8

8 57.8

8 59.7

1

1

8 56.5

8 59.8

8

I

I 56.2

9 59.2

8

1

1 55.5

' 59.2

9

8

1 58.2

8 58.6

8

9

8 58.1

8 58.5 8 57.4

8 8 57-9

57o9

57»6

57.7

57.5

56.9

57.7 57.4
II
t

Scale Feet

MOUNT WEATHER TESTING ADIT

FIGURE

II-5Z

FIG*





VI. DETERMXHATIGN OF THE THERMAL CO&DUCTXVITY

OF ROCK CORE SAMPLES

Ho Eo Robinson

Various physical properties of rock of interest for engineering

purposes can be determined by tests made on rock core samples obtained in

exploratory test drilling of proposed sites, provided that test methods

are available for application to cylindrical specimens „ To take advantage of this possibility, an apparatus was assembled for determining the

thermal conductivity of rock in the form of cylindrical core samples

from J>/k to 1 l/2 inches in diameter and about 18 incheg longo

The thermal conductivities of a few cylindrical samples were determined with this apparatus, by comparative method using a rod of stainless steel of measured conductivity as a reference.

Theory

If a long uniform rod is placed in an ambient of uniform temperature, and one end of the rod is raised in temperature, the termperatue

distribution along the rod after a steady state of temperature is attained is given by the general equation;

T = Ae^2® + BeTM ( 1 ) where

T

x

a

m

is the temperature rise above the ambient temperature,

at a point x

is the distance along the rod from a point taken as X ss O is the bag© of the system of natural logarithms

( 2.7183 ...)

- 1 “ 9 where h is the coefficient ©f heat transfer

kA ) between the convex surface of the rod and the ambient,

P and A are the perimeter and area of a cross-section

of the rod, respectively, and k is its thermal con- ductivity <> These quantities should be expressed in con- sistent unitSo

A and B are constants determined by the imposed conditions.

If the rod were infinitely long, B would be equal to zero and equation

(l) would become

T s T0e

=m3c

( 2 ) if T = T0 at x s Oo

-15“

Tak5”g natural logarithms on both sides of equation (2)

In T s Is T0 - mx (3)

If values of the logarithm of observed values of T at different

positions x are plotted against x, a straight line should be obtained,

the slope of which would give the value of -m„ If data were obtained

for two different rods under conditions where h is the same, the rods

having the respective properties Pp, Ap, kp, and Pg, A2 , kg, and mp

and mg were determined from the slopes of the respective lines, then

£L _ i h?l . k2 k2 m t k2 b2 m

2 | klAi h Pg

|

kl D1

( 4 )

where Dp and ©2 are diameters of the rods, respectively t

Hence, if kp were known.

"(S) C5)

In an actual case, where the rod is not infinitely long, but where

the part of the rod used for the measurements of T and x (o< xc xm) is

somewhat less than the length of the rod, Ls (i,e„, xm < L)

,

equation

(l) can be put into the form

T a T e-ra (l * e-2mL(Wl>

0

V l + e2"L

.

(6)

It will be observed that equation (6) is identical with equation (2)

except for the coefficient of To©”11® in equation (6). The value of

this coefficient is nearly unity for moderate and large values of roL, provided the value of x/L (which has a maximum value of Xm/L) is not

too large. It can be shown that the coefficient in equation (6) will

not differ from unity by more than one percent if

Xm/L— 1 - 2mL

^

Consequently, the relation given in equation ( 5 ) can be used for a rod of practical length (L) with only small error, provided that the

measurements of T are made at values of x less than x®. where xm is

limited in accordance with equation (?)» The value of x® can usually

be estimated in advance of a test to keep the value® of x used in the

test within safe limits

„

-16-

Description of the Apparatus

The thermal conductivity of the rock core sample was determined hy

comparison with that of a reference rod of Type 3^3 stainless steel, 0.85

inch in diameter and 1? inches long, the conductivity of which had previously been determined, hy another method, to he 8.91 Btu/hr ft (deg F)

at approximately the mean temperature at which the rod was used.

The test sample and reference rod were painted with the same hlack

paint to assure that their surfaces would have the same emissivity and

that the corresponding values of h would he equal. They were hung horizontally in line axially in an enclosed chamber 3x1 l/2 x 1 l/2 ft in

size. A few turns of resistance wire were wrapped around the adjoining

end of each rod, so that these ends could he heated to desired temperatures hy passing an electrical current through the windings. Buttwelded thermocouples were placed on each rod in close contact with the

rod surface at four accurately measured positions spaced from 3 to ^ cms apart. These positions were all well within the limits established hy

equation (?)>

The ambient temperature was measured hy two fine wire thermocouples

placed in corresponding positions two inches away from each rod. All

thermocouples were read with their cold junctions at 32° F, using a precision potentiometer.

Procedure and Results

The adjoining ends of the rods were heated electrically with con- stant voltages impressed, until all temperature measurements became

steady, at which time observations were recorded. The heater voltages

were selected to make the steady temperature of each rod at the point

x s o from 20 to 40 degrees F above the ambient air temperature.

For the temperatures used, the difference of the emfs of the rod

and air thermocouples could he taken as substantially proportional to

the temperature difference between rod and air. The emf differences were

plotted as ordinates on semi- logarithm paper against the corresponding

values of x on the linear abscissa scale, for each rod. It was found

that the points for each rod conformed closely to straight lines (see

Figure l), the slopes of which were determined to yield the values of

,! m" used in equation (5) to calculate the thermal conductivity of the

test sample (see attached sample calculation). Table 1 shows the thermal conductivities of several samples determined in this manner. For

comparison, the last column of the table gives values for similar

materials from a compilation by Francis Birch.

" 17“
_• •* t

. 1
<*»

<ro

Table 1

Avg. specimen

Material temoerature Thermal conductivity, Btu/hr ft (dee

• °F Observed Published data'i'

"Greenstone”^ 82 1.44 1„33 (Md„ diabase)

Granite'^ 88 1,6? 1.22-1,74

Gneiss 85 1,48 1.04-1.62

Pyrex glass 79 0,58 0.59

^

From Handbook of Physical Constants, Special Paper No. 36 , Geological

Society of America, pp. 251=260

„

From Mt. Weather, 7a.

From Woodstock, Md.

Discussion

The observed thermal conductivity values are near, or within the

range of, values published for similar materials . Because of the incompleteness as regards petrographic identity of the materials involved in the comparisons, a sharper comparison is not feasible.

The test method and apparatus are relatively simple to set up and

operate, and with good laboratory techniques it §eems possible to obtain results in successive tests on a specimen agreeing within about

t 5 percent. This includes the element of judgment involved in drawing

the lines illustrated in Figure 1,

- 18.

Sample Calculation for Gneiss (Figure l)

From Equation 5

c

\ m2 J $2 1

Btu

k]_ s 8o9! >

* , s thermal conductivity of stainless

steel reference

5i -

®

°

s 0„99 ratio of diameters

D2 0.86

ml - s 0°64 proportional slope for stainless steel as

° ^ measured from line in Figure 1

®2 s ~ 1»56 proportional slope for gneiss as measured

0 cm from line in Figure 1

*2 '( i 75s)

2(0 -" )(8 - 91) ‘ 1Aa £Tn °F

- 19-

VII . heat TRANSFER PROBLEMS AT THE FORT RITCHIE

UNDERGROUND SITE

Bo A 0 Peavy

Acting under a verbal request from Messrs, Kirkpatrick and Letts

of the Office of the Chief of Engineers, a study has been made of two

heat transfer problems at an underground site near fort Ritchie, In

general, these problems ares

1, Determine the effectiveness of the rock bounding a vehicular tunnel as a heat sink,

2, Determine the effectiveness of the rock bounding a water reservoir as a heat sink.

Heat Transfer to Rock Surrounding a Vehicular Tunnel

In accordance with present plans, during an emergency and with

cooling- tower services impaired, air from the structure will be drawn

along the vehicular tunnel by a 3^,000 cfm alert fan located in the fan

room 1,000 feet from the structure to which it is returned through a

duct. The purpose of this is to dissipate heat from the warm air to the

rock of the tunnel in order to reduce the load on the air cooling equipment, No definite schedule of operation has as yet been established for

the above equipment during emergency periods, consequently, in what

follows, necessary assumptions have been made.

It is assumed that during the time that the vehicular tunnel is to

be used as a heat sink, the heat input to the structure will be constant

and that the cooling load will be aecomplisned, by tne combined effects

of the air cooling equipment and the loss of heat to the surface of the

vehicular tunnel. It is further assumed that the mean temperature of the

air in. the tunnel will be 75 ® F and the initial temperature of the rock

bounding the vehicular tunnel 58 ® F„ This assumption implies that the

heat flux at the rock surface will decrease with time and the change

in rate of heat absorption by the tunnel rock will be made good by the

air cooling equipment.

-20-
11I<1
The heat "balance for heat transfer from the air to the rock sur- face of the tunnel is;

Q = H(u - v) = t a a

where Q, s heat flux, BTU/hr ft2

H = coefficient of heat transfer from air to the rock surface

BTU/hr ft2 deg F

u = constant mean air temperature in tunnel, deg F v = mean rock surface temperature, deg F

K = thermal conductivity of rock, BTU/hr ft deg F

r = position in the rock from the axis of the tunnel, ft a = equivalent cylindrical radius of tunnel, ft.

The rate of heat flow into the rock "bounding a tunnel of radius a

is given for the conditions assumed above, and for moderate values of

time, "by the following equations

q, = g'^2a^'E

” h ^0)

1 ^ 2

~

t 1 * 2ah + Q ) enerfc fnj

where c< = thermal diffusivity, ft^/hr

h = H/K, ft" 1

t = time, hrs n - °C th^, dimensionless

enerfcfn is plotted on figure 4

Substituting values K - 1.45 BTU/hr ft deg F, H =? 1.0 BTU/hr ft2 deg F,

oC=s 0.039 ft2 /hr, a =? 15.9 ft, and u = 75 deg numerical results obtained from the above equation for various values of time are shown in

Figure 1 for which the surface area of the 1,000-ft tunnel is taken to

be 100,000 ft 2 .

It should be noted carefully, however, that although the rock tunnel is capable, under the assumed temperature conditions, of absorbing

heat initially at the rate of about 1„7 x 10^ BTU/hr, the maximum heat

delivery to it by J>0,000 efm of air changing temperature from 75 deg to

58 deg F is only about 0.55 x 10^ BTU/hr. If the fan delivery were increased three times, maintaining the assumed temperature conditions,

heat delivery to the rock might approach that shown in figure 1.

The heat absorbing capacity of the tunnel is, therefore, less

governed by the rock than by the volume and average temperature of the

air in excess of rock temperature. The total heat absorbing capacity

of the rock under the assumed conditions, over the initial period of seven days, as taken from figure 1, amounts to 102 x 10° BTU, corres- ponding to a level average rate for the period of 0.6l x 10 6 BTU/hr.

Since the heat-absorbing capacity of the rock of the tunnel increases

as the rate of heat input is reduced, the rock should be capable of

absorbing heat at the rate of 0.6 x 10° BTU/hr for a period in excess

of seven days, or of absorbing substantially more for periods less than seven days.

-21-
I r ; '

..... 1 '
Heat Transfer to Rock Surrounding Underground Reservoir

The heat transfer to the rock surrounding an underground reser- voir was computed “by the architect engineer -under W, D, Contract

No. 57 (communication of H, A. Foster dated March 3 » 1953) • Another

approach to this problem with the present assumptions is that there

is a constant volume of water in the reservoir and the entire surface

area (excluding the dam face) of the reservoir is in contact with the

water

o

The physical problem is to determine the heat transferred to the

rock surface of a 23O by JU by 29 ft high water reservoir holding

approximately 1,525,090 gallons. Heat is transferred to water flowing

through the heat exchangers of refrigeration condensers and Diesel

lubricating oil and jacket coolers at assumed rates of 5, 6, ajid 7

million BTU/hr, The water is returned to the reservoir, heating its

contents. At the same time, some of the heat is transferred to the

rock surface which has an initial temperature of 52® F, The water is

constantly recirculated in this system. After a period of time, the

water will not be useful as a heat exchange medium due to an excessive

rise in temperature and it is this time which is to be determined.

•Tbe heat balance for heat transfer to the rock surface of the

reservoir is?

which assumes that at any time the mean temperature of the water and

rock surface are equal and whereg

M weight of wafer per unit length of cylinder, Ibs/ff,

c

8 = specific heat of water, BTU/lb deg F.

K ss thermal conductivity of rock, BTU/hr ft deg F.

Q, s heat transfer rate to water per unit length of cylinder

(constant) BTU/hr ft,

Q,

0 heat transfer rate to rock surface per unit length of

cylinder, BTU/hr ft, v ~ mean temperature of water and rock surface above the initial

temperature of water and rock at t = o, deg F„

t = time, hrs,

a s equivalent cylindrical radius of reservoir, ft,

c<! s thermal diffusivity of rock, ft^/hr.

n - th " ^

enerfe fn is plotted on figure 4,

- 22-

j
.

:-
The relationship derived from assuming the rock is internally

hounded hy a cylinder of radius a and for moderately short values

of time is ;

feah 8 + 3 'o^y/ 2

wJ ~^-j(l - enerf e fh) ~*TT\1 + 2 enerf c fn)

^ *q[(i + enerfc Vn 1

a

. <th* *4“ —=—

a

enerf

c

Substituting the following values for the constants;

K

oC

a

i M

Q,h s

2

^"x 20 °7 x — = 0 o 0876/ft

55,300 x i o 0 xO .039

various times

In the above equations, values at/of rock surface temperature and the

rate of heat transfer to the rock surface of the reservoir are shown in

figures 2 and 3 for heat inputs of 5. 6 , and 7 million BTU/hr. Also

plotted on figure 2 is the temperature rise of the water with time, assuming that no heat is transferred to the rock.

With a heat input of 6 x 10^ BTU/hr to water, assuming that the maximum allowable temperature entering the refrigeration condenser

will be 90® S', the mean temperature of the water in the well-stirred

reservoir should be 90 ® S' or, referring to figure 2, a time of 88 hours

or 3„7 days will elapse before the reservoir will no longer be useful as

a heat exchanger. The gain in time over what would be expected if heat

is transferred to the water only will be 8 hours. If higher water temperatures are allowable, the gain in time would be increased.

With a heat input of 5 x 10^ BTU/hr and the above assumptions, the

elapsed time will be 106 hours or 4.4 days before the reservoir will no longer be useful as a heat exchanger and the gain in time over what

would be expected if heat is transferred to the water only is 9 hours.

= 1.45 BTU/hr ft deg F

s 0.039 f

t

2 /hr = 2 W(68 + 58) ± a. * 29 , 20.7 ft

2TT230

= 1°5 25 x x 8^34 _ 55,300 lb/ft of reservoir

ss 21,720; 26,100; J>0,k20 BTU/hr ft of reservoir
.

'

-
HEAT

LOSS

TO

TUNNEL

ROCK

SURFACE

(IQ

5

FT. 2

4-HUH/ni8 ‘H3dSNVHl ±V3H JO 3±Vd

IOO

'

150

200

250

300

350

TIME

IN

HOURS

TEMPERATURE

OF

RESERVOIR

ROCK

SURFACE

-qxr.

-» rH i#

do ‘3UniVU3dlN31

120

160

200

240

280

TIME

IN

HOURS



t: HW

1+

_Ny\0dU3N 3

FIG.

4

VIII. REPORT OF OBSERVATIONS ON AIR CONDITIONING EQUIPMENT IN UNDERGROUND

INSTALIATIONS NEAR ATCHISON, KANSAS AND ALBUQUERQUE, NEW MEXICO

J, C. LETTS (QCE) AND R, S„ DILL (NBS)

1 D ITINERARY

On J>0 August, Jo C„ Letts and R. S„ Dill left Washington "by B&O RR for

the purpose of gathering data and information on the performance of air conditioning equipment now in use in underground protective structures near

Atchison, Kansas, Albuquerque, New Mexico, and Temple, Texas , The first

stop was at Kansas City, Missouri, for consultation with representatives of

Black and Veatch Company, Architect Engineers for the sites near Albuquerque

and Temple, Due to cancellation of the airline flight from Albuquerque, the

visit to Temple was omitted and data gathered on that installation are

those obtained from the Architect-Engineers, Letts and Dill returned to

Washington 11 September,

2.. Persons Interviewed

The following persons were consulted concerning the design and operation of the air conditioning systems of interests

At Kansas City

Mr, Bo F, Steves, Engineer, Black & Veatch

Mr, Jo C„ Robbins, " " Mr, Do P. Groshens, ,! Tulsa District, Engineer Corps

At Atchison

Mr, Van Marter, Manager, Page Airways, Inc,

Mr, D, Vo Case, Engineer, USBA, Retired

At Albuquerque

Lt, Col, Jo Co Hogle . Engineer, Construction Branch, Headquarters,

Field Command

Capto John Co Ward

Mr„ Jo T„ Fallon

Mr, Clives, Plant Operator

Mr, Ho W, Fenn, Plant Operator

3. Observations at Atchison

The installation near Atchison is under Contract Operation by Page

Airways, Incorporated of ^Rochester, N„Y. It is described in a report,

undated, signed by Lt„ Col„ E, M„ Serrem, Ordnance Corps, which forms

part of a brochure received from Mr. Van Marter, manager for Page

Airways, Inc»

Limestone was mined from this site, beginning about 1886, resulting in a cavity with a fairly level floor, about 15 acres in extent,

« with a ceiling height of about 12 feet and a rock and earth over-lay of

from 40 to 100 feet. During a food storage shortage incident to World

War II, the site was taken over by the Department of Agriculture, a large

brine refrigerating system was installed, and the space was maintained at

32° F for about seven years beginning in 1945° Installation and operation

of the refrigerating equipment was under the supervision of Mr* D. V. Case.

The original refrigerating equipment consisted of three 400-ton ammonia compressors, each with a 6Q0-HP motor, a cooling tower for condenser

water and heat exchangers for chilling the brine . The space was cooled

by mean® of 48 unit coolers to which the brine was pumped from the heat

exchangers through a circuit of 8-inch pipe. Mr. Case reported that 26

days were required to cool the space to 32® F from the initial temperature

of 57® Vo Thereafter, the cooling equipment was found to be considerably

excessive in capacity, so much so that the three original compressors and

motors were exchanged for two smaller units each having a 320-HP motor.

- 2-

After seven years' operation as a cold storage chamber, the plant

was shut down and lay idle until about the fall of 1952 when operations

commenced to warm it for use as a machinery storage space „ Heat was

sunnlied by a boiler, presumably through a heat exchanger to the brine

circulated through some of the unit coolers,, Much water resulted from

the melting of the ice on the brine lines and, apparently, on and in

the rock and this water was removed by means of sump pumps . later, the

refrigerating machines were started and dehumidification was accomplished

by means of part of the unit coolers. This operation proved expensive

so it was changed such that now part of the unit coolers are used for

dehumidification while another part are used to cool the condenser water

for the refrigerating machine. The cooling tower was valved out of the

circuit. The system was operating in this manner on the occasion of

this visit.

Since the underground site served as both heat source and sink,

the refrigerating machine would be expected to deliver more heat to the

site than it removed from it in the manner of a heat pump. The temperature in the site should therefore rise except for the heat absorbed

by the . surrounding rock and that removed by ventilating air. Engineering data on the installation under this regime of operation were gathered

as follows:

- 7-

Table 1. OPERATING DATA,, TYPICAL DAYS - ATCHISON

Operating data 8 Date, 1953

0

I March 19 June 18 ’

0 August 28

Outside temperature , approx., &vg„

1 °p—

'

8 45 78 80

Inside temperature, Chamber M A

W oy—

«

0 66 73 78

It )! 10 WjjJJ °F~ «

8 72 74 74

W 10 n wqio 8

0 57 55 74

M wet bulb temp.. Chamber M AM 0

0 53 60 60

It It [i « 03 M °r— 1

8 56 60 58

Hi #S ID II io ii q

n b

fl 51 52 55

Units used for cooling Ho.— '

0 12 11 9

•" M M heating No.— '

0 32 32 29

Brine circulating rate, each unit GPM—

=

8

« 50 50 50

Refrigerating effect Ton©-” 8

0 203 184 135

Heating effect, refrig. machines Tons— 8

8 240 240 220

Net M w w 00 Tons— 8

1) 37 56 85

M 10 10 W M Btu hr"l— 0

0 440,000 672,000 1,020,000

Heat input, electric mo tors,etCo 00 __ 8 1,065, 919,000 895.000

Total heat input

0 n __ o 1,509,

j

000 1,611,000 1,915,000

oo oo m

^ average M __ 8

0 1,678,000

Heat absorbed by structure ,Btu hr ^ ft"2 — 8

8 1.7

The data in Table 1 are considered indicative although high accuracy cannot be claimed for them because the observations on which

they are based were made by plant personnel with uncalibrated instruments , temperatures were instantaneous or "’spot" readings, etc. The

refrigerating effect was estimated on the nameplate brine circulating

rate for the unit coolers in use as dehumidifiers and the heating

effect of the refrigerating machines within the underground site was

estimated in the,j§ame way. The heat input due to electric motors was

estimated from the readings of a watthour meter which measured the

power received by them.

The water condensed from the air in the dehumidification process

is gathered in a measuring tank on a truck and the plant log sheets

showed consistently that the rate is slightly in excess of 1,000 gal=

Ions per day. This accounts for about 30 tons of the refrigerating

capacity now being utilized.

The ventilation of the site is held at a minimum. Fresh air is

admitted for short periods and only when there is reason to suppose

the air in the structure is becoming vitiated. For this reason,

ventilation is ignored in the above heat transfer estimate.

On the occasion of this visit, operating conditions were observed as shown in Table 2,

Table 2

Head pressure 180 psig

Suction pressure 25

' " Brine temperature, supply 31® F

w M

, return 39® F

Condenser water, supply 87® F

w M

, return 92® F

The data in Table 2 indicate that the refrigerating machines are

operating through a pressure range almost as great as if they were

making ice, There is reason to believe that the power consumption

could be considerably reduced if the cold air from the unit coolers

could be used to extract heat from the units now being used for cooling the condenser water. It might be possible to aeconplish this by setting units being used for dehumidification next to units being used to

cool condenser water and connecting them by means of a duct so that the

cooled air from the one would cool the condenser water flowing through

the other,, This arrangement would permit lowering the head pressure

against which the refrigerating machines must work and would, therefore,

be expected to save power. The arrangement would not be as effective

as dehumidification units containing both a dehumidification coil and

a condenser cooling water coil in the same cabinet and with a single

motor-driven fan for both, A choice between these procedures must be

based upon a detailed analysis of the factors involved.

With either of these arrangements, it is unlikely that the heat

due to the dehumidification process will exactly equal the heat requirements of the space. In fact, gradual temperature rise can be

expected in this installation and, for this reason, dismantling of

the present refrigerating equipment is not recommended. This equipment, including the cooling tower, may be essential for controlling

the temperature within the site if it is in use for a few years.

- 6-

4 . Observations at Monsanto Base

The installation examined at Monsanto Base occupies a series of

interconnected tunnels in hard rock with a number of enlargements which

serve as work rooms. The rock cover appears to vary in depth from about

100 to 200 feet or more. The engine room inspected, vrhich is also underground, contained a Diesel engine-generator set of 400 KW capacity and

air-conditioning equipment for the installation including a bank of four

absorption- type (Bryant "29R") dehumidifiers, a J,0-kon mechanical airconditioning machine, an oil-burning steam boiler, an evaporation cooler

for the engine jacket water, and necessary fans or blowers and auxiliary

equipment. Air is brought down to the engine room from the surface of

the mountain through a vertical shaft 36 inches in diameter and 112 feet

high. This air is used for combustion in the engine and boiler when in

operation, for cooling the condenser of the air conditioner and the

engine jacket water, and for fresh air supply to the installation.

The Diesel engine is now operated only about 8 hours per week for

maintenance purposes and the bank of dehumidifiers is operated only when

the relative humidity in the installation approaches the limit, 5

0

percent, set by the operating instructions. Table 4 "Operating Conditions"1

shows that it was necessary to operate the dehumidifiers only 458 hours

during the calendar year 1953° The humidity in the installation appears

to depend more than the temperature upon external conditions. The air

conditioner is operated only when either the Diesel engine or the dehumidifier-boiler combination is operated and then for the purpose of

keeping the engine room tolerably cool, not for cooling the working

portion of the installation. The boiler supplies heat for reactivating

-

7

-

the dehumidifiers so that operation of the holler is necessary when the

dehuraidif iers operate.

The data gathered at the Monsanto Base, and shown in Tables 3 and

4, indicate that the surrounding rock is absorbing all the heat generated

in the installation, except that removed by the ventilating air, without material assistance from the air-conditioning machine. Absorption of

this heat is gradually raising the temperature in the structure so that

removal of some heat by mechanical means can be expected to become essential in the future. The net heat generated in the installation, that

is, the difference between the total power consumed and the heat removed

the ventilating air, is less than the capacity of the air-conditioning

machine, on a yearly average basis. Therefore, the installation probably

can be kept from becoming intolerably warm by means of the present air

conditioner and the ventilating air. This would not be so if the Diesel

engine were operated for a long period. In that case, the present air

conditioner would have to be used to cool the engine room and other means

would be necessary to cool the working space of the installation. Also,

it would not be true if it were necessary to operate the dehumidifiers

for a long period. However, the climate at this site, with the usual

low humidity and dry earth, is so favorable that continuous dehumidification for long periods is not likely to be required.

itine ragy

Arrived at base September 3

Visited plant " 4 and 5

Departed from base " 6

- 8

-

Table 3„ MG-INEERING- BATA - PUNT NO, 1

Data Source

Floor areas 65,912 ft2

Wall and ceiling area; 277,000 ft^

Total internal area; 343,000 ft2

Air flows Supply 19,^75 0FM

Fresh 5,000 CFM

Return 14,475 CFM

Air filters (total air) 18 - Owens Corning 20 x 20 in.

Dehumidifiers - 4 Bryant M 29R" - 2900 CFM

Plant was put in operation, 1948

Max, electric load in plant (sum of capacities) 280 KW

Power input - typical month - 130 KW, average

Boiler, 60 hp, oil “burning

Air conditioner J>0 ton

Plant altitude 6,000 ft, approximately

Mean annual temperature 56® F

” range 0® F - 110® F

' Ward

Como, No» 1

M W

Fenn

Nameplate

Ward

Ward

Ward

Fenn

Nameplate

Ward

Well water

Ward

=9

Table 4 0 OPERA-TING CONDITIONS - 10 AM September 6

Operating conditions Source

i

Wall temperature, corridor 74 „ 5® F

, engine room (K-l) 75® F

s

8 Thermometer in holt

8 hole

8 do

o Floor 58 , corridor 76® F

Air conditions by Plant instruments

s

Supply 71® DB 57 WB 41# EE

Fre sh 73® 59 42#

Ee turn 75° 59 37#

Air conditions hy Sling Psychrometer

Supply 76 58

Fresh 75 o 5 58

Re turn 76»5 58

8 Thermometer in drain

8

8

1

J

c

8 Outdoor conditions?

Sandia =* 9 ^M ~ Wind,

72® DB

Main portal - noon;

79 o 5°

S i. 12 MPH (estimate)

57 WB 38# EE

57»5 25#

8

8

8 Sling psychrometer

0

8

8

8

8

1

8 Diesel engine - generator set 400 KW 1 Burns 24 G„P„H„s ‘

8 Operates 8 hrs per week for testing 8 Ward

8 Dehumidifier - operated total of; 8

June, 1953 77 hrs

0

, Engine Room

July 255 18

1 ho

AUge 107 "

o ho

Sent, 19 "

0 ho

Total, 1953 458 "

8

Log Book

Boiler - 60 Ep - Burns 12 G,P,Ho of Diesel Oil 8 Fenn

I Operated when dehumidif ier operates , Log hook and Fenn

Operates occasionally in winter to warm 8 engine room

Air conditioner - 3^ ton 1

0 Operated when engine operates to cool engine rm ( Log hook and Fenn

Operated when dehumidifier operates to cool

supply air; capacity insufficient for both

- 10-
.

-

.
Table 5 . COMPUTATIONS

(1) Heat equivalent of electrical inputs

130 x 3,415 = 444,000 Btu hr" 1

-• 37 tone

(2) Heat input per sq ft of rock area, gross

444,000/343,000 = 1.3 Btu hr-1

(3) Refrigerating effect of fresh air

(Based upon mean annual temperature of 56° F);

5,000 x (75 - 56) x 1.08 = 102,600 Btu hr"1

(4) Heat input, nets

444,000 - 102,600 = 341,500 Btu hr"1

ss 25 »5 tons

(5) Heat input per sq ft of rock area, net;

341,500/343,000 = 1.0 Btu hr" 1

(6) Estimated rock temperature rise due to net heat inputs

3.1® F per year

11-

DISCUSSXOII

The data gathered indicate that in the Atchison site the rock sur=

rounding the site is absorbing about 1.7 Btu per hour per square foot

and that it has been absorbing heat at this rate for half a year with a

small but unknown temperature rise which eventually will require use of

some air conditioning means to keep the temperature within tolerable

limits. Indications are that the heat acceptance of the rock in this

case is greater than that occurring either at the Albuquerque site or

in the experimental chamber at Mt. Weather. This may be explained by

the precooling of the rock when the Atchison site was refrigerated for

use as a cold storage space.

The net heat acceptance of the rock at the Albuquerque site, close

to 1.0 Btu per hour per square foot, is below that observed at the Mt.

Weather site and is of the order expected for rock after several years

of occupancy of a site. It is to be noted that at Albuquerque the air

conditioner is only operated when either the dehumidifier or the Diesel

engine is operated and then for the purpose of the engine room. However, Table 5 shows that the capacity of the air conditioner exceeds the

net mechanical input so that the possibility is good that this plant can

be operated in future by judicious use of the ventilating air and the

air conditioner without additional equipment.

Excessive water is not a problem at either Atchison or Albuquerque.

In damper regions, additional air conditioning capacity, particularly

dehumidifying capacity, will be required.

- 12-

NATIONAL BUREAU OF STANDARDS REPORT

2895

ON A CERTAIN INTEGRAL INVOLVING BESSEL FUNCTIONS

by

H. A. Antosiewicz

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Week*, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards is suggested in the following listing of

the divisions and sections engaged in technical work. In general, each section is engaged in specialized research, development, and engineering in the field indicated by its title. A brief description

of the activities, and of the resultant reports and publications, appears on the inside of the back

cover of this report.

Electricity. Resistance Measurements. Inductance and Capacitance. Electrical Instruments. Magnetic Measurements. Applied Electricity. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology. Length. Gage.

Heat and Power. Temperature Measurements. Thermodynamics. Cryogenics. Engines and

Lubrication. Engine Fuels. Cryogenic Engineering.

Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid State

Physics. Electron Physics. Atomic Physics. Neutron Measurements. Infrared Spectroscopy.

Nuclear Physics. Radioactivity. X-Rays. Betatron. Nucleonic Instrumentation. Radiological Equipment. Atomic Energy Commission Instruments Branch.

Chemistry. Organic Coatings. Surface Cheipistry. Organic Chemistry. Analytical Chemistry.

Inorganic Chemistry. Electrodeposition. Gas Chemistry. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics. Sound. Mechanical Instruments. Aerodynamics. Engineering Mechanics. Hydraulics. Mass. Capacity, Density, and Fluid Meters. Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Polymer Structure. Organic Plastics. Dental Research.

Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion.

Mineral Products. Porcelain and Pottery. Glass. Refractories. Enameled Metals. Concreting Materials. Constitution and Microstructure. Chemistry of Mineral Products.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Floor, Roof, and Wall Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Machine

Development.

Electronics. Engineering Electronics. Electron Tubes. Electronic Computers. Electronic

Instrumentation.

Radio Propagation. Upper Atmosphere Research. Ionospheric Research. Regular Propagation Services. Frequency Utilization Research. Tropospheric Propagation Research. High

Frequency Standards. Microwave Standards.

Ordnance Development. These three divisions are engaged in a broad program of research

Electromechanical Ordnance, and development in advanced ordnance. Activities include

Ordnance Electronics. basic and applied research, engineering, pilot production, field testing, and evaluation of a wide variety of ordnance materiel. Special skills and facilities of other

NBS divisions also contribute to this program. The activity is sponsored by the Department of

Defense.

Missile Development. Missile research and development: engineering, dynamics, intelligence,

instrumentation, evaluation. Combustion in jet engines. These activities are sponsored by the

Department of Defense. • Office of Basic Instrumentation • Office of Weights and Measures.
NATIONAL BUREAU OF STANDARDS REPORT

MBS PROJECT NBS REPORT

1102-10-1104 October 26, 1953 2-395

ON A CERTAIN INTEGRAL INVOLVING BESSEL FUNCTIONS

by

H. A. Antosievvicz

National Bureau of Standards

The American University

<NBS>

U. §. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, reprinting, or reproduction of this report In any form, either In whole or In part, Is prohibited

unless permission is obtained In writing from theOftice of the Dl rector, National Bureau of Standards, Washington

25, D. C, Such permission Is not needed, however, by a Government agency for which a report has been specifically prepared If that agency wishes to reproduce additional copies of that particular report for Its own use.

ON A CERTAIN INTEGRAL INVOLVING BESSEL FUNCTIONS*

by

H. A 0 Antosiewicz

This note deals with the integral

oo ,2 J (rx)Y (ax)-J (ax)Y (rx) kx t o o o o dx

ir x

which arises in the solution of the equation of heat flow

in a region internally bounded by a circular cylinder with

constant surface temperature [1, pp. 280-282], Its evaluation for large values of t presents certain difficulties

because the standard Abelian theorems for Laplace integrals

are not applicable. Although asymptotic expansions of

similar integrals can be found in the literature [1,3)^+]?

they generally are stated without explanation of their derivation, It seems desirable, therefore, to bridge this

gap by giving a rather complete discussion, which may

prove useful in the evaluation of related integrals.

The problem was brought to our attention by B. Peavy of

the National Bureau of Standards; we appreciate his interest

in the publication of our result in this form.

*This paper was prepared under a National Bureau of Standards contract with The American University,

1 . Let
-2 -

(1) F (x) =

J (rx) Y (ax)-J (ax) Y (rx)

O O 0 o

[

J

o 2 (ax)+Y

o 2 (ax) ] .x

and put

(2) f(t)

oo - 1 f -kx t " ^ J

F (x)dx

where it is assumed that a, k, r are positive constants

From the definitions of the Bessel functions J (z),

o

7 Y

q

(z) we obtain the expressions

(3) J (rx)Y (ax) - J (ax)Y (rx) = § £n 7 [

1 + 0(x 2

)]

(4) J

2 (ax) + Y2 (ax) = [ 1 +

(f /n •2M

ut

) 2

][ 1 + 0(x2 )]*

where, as customary, 0 (x ) denotes a function ^(x) such

tha t|^2?(x)/x 2

< A for some A > 0 as x

?0, Consequently,

we find

(5)

F (x) = | in f

[1 + (2 /„ -i^) 2 ]- 1 =

r 2

1 + 0(x2

) x

= Tr in

r + G(x)]

where the function G(x) is such that G(x) = 0(x ) as x—s>0

and G(x) = 0(e ) as x —?oo, Thus, F(x) has an infinite

discontinuity at x = 0 , and the integral in ( 2 ) is for

any(finite) value of t an improper integral. However, if

*Throughout , if = C = 0.577. •» Euler's constant

io ueeiiiQ XenoxJBld s lau...

. \ 3 x a ‘i © v i oU n s ax *3 amA o n * .

.
-

3

-

we denote by g(x) the numerator in the second expression of

(5) and note that |g(x)| <_ M on any interval 0 <_ x <_X, then

for any sufficiently sraall£,p > > 0

( 6 )

r£2

j

g ( x ) [ 1 dx

x

< £2 < u( [1 + (fin if) 2 ]- 1 f

=

: 1

= [arctan(“ /n ]

7r < arc tan

2

2 /

^ 2%

( ~ /n —)

<-

so that the integral in (2) certainly converges at its lower

limit for any value of t_> 0. The convergence at its upper

limit is evident*

It is to be noted that the fact that the integral in (2)

is an improper integral a fortiori precludes the possibility

of using directly numerical methods for its evaluation.

And this, of course, holds true regardless of the value of

t for which (2) is to be calculated.

2. In analogy to the asymptotic theory of functions

defined by Laplace integrals it can be shown that the important contribution to f(t) for large values of t will

come from the values of F(x) near x = 0. Hence we need to

consider the two integrals, obtained by substituting the

expression (5) into (2), namely.
4-

f(t) = % £

00

7T n —

a f( " jo

r

kx l

[i + (|/n 4“) 2

] -1 M ?r 2

J x

( 7 )

00

1 e kx t .G(x)[l + (“A :22

'ax

) 2

]

1 ^x

= f

1 (t) + f

2

( t)

We shall first deal with the second integral f

2 (t).

2 Putting y = kx in f 2

(t) we find

00

(8) f

2

( t ) = ^ Xn ~ f e yt G(7yA)[l + (*=£n 7f)

2

]

1

7r o The integral on the right is clearly a Laplace integral to

which we can apply the standard Abelian theorems of the

asymptotic theory of Laplace integrals [2, p, 202], We con

elude that for t—> oo

(9) 1![1 + (f/nTf)

2 ]' 1 (1/t)

where c = [ if a/(2-/k) ] and B is the constant implied by

G(Vy7k) = 0 (y ) as y—^ 0

«

3. We now come to the much longer discussion of the in

tegral I(t) in f ^ ( t )

,

i.e.

(10) I(t) = Je _kx2t

[l + ( 2

r /n -^) 2

] _1

.

y

*
-5

Putting kx = (1/c )y where c = [ Y a/(2Vk)] we find

OOL _ t

(11) I(t) = i

| e o

00

7

2

[1 + (f^ny)

2 ]" 1 dS =

e

c d(orctnn ' ^-

n— )

Performing an integration by parts on the last integral, we

obtain

or> oo t

1(0 = ?[ e

C arctan

^

e ^arctan ( (12)

it J 2

o

7T O

2

00 _ Jb ip + f C e

C

are tan Ay d(^y) ,/t

o

00

We now let ty - czj noting that

J'

e 7dz = 1 , we then can

o write

2

00

I(t) = p" + f e 7arctan [ 2

r oo (13)

7T2

f e "arctan [-^^7 ]dz = J o

f f e~

7dz + re-zarctan[-Ai^Zt)]7

JLilLc z/t

)

dz

/f °° e~

7

+ arc tan[

I

rr ] r dz,

Recalling that arctan (oo) = tt/2 and making use of an elementary trigonometric identity, we finally obtain from ( 13 )

O

|c*
-6 -

oo (1^) Kt) = e 7arctan [v/(y£n J dz.*

In this integral we put s -

JLx\ ~ which yields

oo

(15) I(t)= 0 ( s ) = " e Cretan [ <rs/( s /nz - 1)] dz

00

7T2

e Cretan [tts/( 1 - S/^nz)] dz

It is this last integral which we shall evaluate for snail s«

To obtain an asymptotic representation of (1 5) for

s —*0 we shall prove that

C

1

6

) lira — | e 7arctan ['""s/(1 - sA,n7)]d7 - 1T . s—>0 s

We must show that given any > 0, however small, there

exists a ^

(£) > 0 sue!) that

07)

ooT e 7 arctan [^s/(1 - s^nz)]dz - 7r

| < £

for all s < K? (£,) . Evidently, this inequality will be satisfied if for all s < *9 (€,

)

*The use of the trigonometric identity involving arctangents

was pointed out to us by P. Iienrici. Our original argument

was somewhat longer.
7-

4U S'

J"' e 7 arctan [tts/(1 - s^nz)] - 7r

j- dz| +

( 18 ) 0

oo a

+

j ^

e 7 " arctan [tts/(1 - si?nz)]dz| + IT dz < £

where 7 > 0 is some constant at our disposal. Since the

function

(19) h(t,z) - y

arctan [^t/(1 - t/nz)]

is uniformly bounded for all z and all t > 0 and h(t,z) —

as t—*0 for z finite, we have

oo oo (20)

| ^ e 7 ^

arctan [tts/( 1 - s /nz) Jdi <K j e 7dz = Ke ^ Z

_7 £ Choose Z > 0 so large that max (Ke J , ire ) < - , Then all

we have to prove is that there exists a ^

(£) > 0 such that

(21 ) (

j ^

\ ~ arctan [tts/(1 - s^nz)] - 7rj<jz| <

o

^

for all s (£) . This, however, is now trivial since the

boundedness of h(t,z) and h(t,z) —?0 as t—*0 together

imply the bounded convergence of (21) to zero as s —»0,

By virtue of (16) we can conclude from ( 15 ) that for

s —* 0

(22) 0(s)~ ~ s
- 8-

whence for t—* oo

(23)

J2. I(t) ~ 2 in(t/c)

Recalling that we have from (7) and (10)

(24)

we finally obtain

(25) f-|(t)^

f

1 (t) = in *) I(t)

7T

Jin—

r r ^nt - Jlnc A4tk - 2 tJln'X a

If we compare this relation with that derived in (9) for

f^(t), we see that for sufficiently large values of t the

contribution of f 2

(t) to f(t) can be neglected.

Thus, the behavior of f(t) for large values of t is

described by the asymptotic relation

C26) f(t) ~/n4tk -

5. It is possible to derive similarly higher order

terras in the asymptotic relation (25) for f^(t). In fact,

we can obtain in this manner the asymptotic expansion

(27) f

1 (t) ~in "

t^niftk

1 - 2ing> a “ XJ n^xC- 2^nya) 2 +•••]

for t —>oo . In view of the asymptotic relation (9) for

f

2 (t) this expansion can be considered as an asymptotic
-9-

expansion, in the sense of Poincare^, of the function f(t)

for t —^oo .

In conclusion we remark that the expansion

(28)

oo

i r

IT

-kx^ t dK^i[ a

J ^(ax) + Y ^(ax) x 2 a4tk -

jay

(,^n5-tk - 2^a jfa)

2

can be found in the literature [1,3,^], where it is stated

without derivation.

REFERENCES

1. Carslaw, H.S. and Jaeger, J.C. Conduct ion of Heat in

Solids . Oxford University Press, 19^+7.

2. Doetsch, G. Theorie und Anwendunq der Laplace-Tr ansf orraa- tion . (American Ed.). Dover Publications, 1 7+3.

3. Goldstein S. Some two-dimensional Diffusio n Problems with

C ircular Symmetry . Proc. London Math. Foe., vol.

3^(1 932) , pp. 51-88.

*+ . Jaeger, J. C. Heat Flow in the Region bounded Inter nally

b y a C ircular Cylind er. Proc. Roy. Soc. Edinburgh

(A), vol. 6709^2), pp. 223-228.

The American University
•V • -

-

.

C

'
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act of Congress, March

3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and

maintenance of the national standards of measurement and the provision of means and methods

for making measurements consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials,

devices, and structures; advisory services to Government Agencies on scientific and technical

problems; invention and development of devices to serve special needs of the Government; and the

development of standard practices, codes, and specifications. The work includes basic and applied

research, development, engineering, instrumentation, testing, evaluation, calibration services, and

various consultation and information services. A major portion of the Bureau’s work is performed

for other Government Agencies, particularly the Department of Defense and the Atomic Energy

Commission. The scope of activities is suggested by the listing of divisions and sections on the

inside of the front cover.

Reports and Publications

The results of the Bureau’s work take the form of either actual equipment and devices or published papers and reports. Reports are issued to the sponsoring agency of a particular project or program. Published papers appear either in the Bureau’s own series of publications or in the

journals of professional and scientific societies. The Bureau itself publishes three monthly periodicals, available from the Government Printing Office: The Journal of Research, which presents

complete papers reporting technical investigations; the Technical News Bulletin, which presents

summary and preliminary reports on work in progress; and Basic Radio Propagation Predictions,

which provides data for determining the best frequencies to use for radio communications throughout

the world. There are also five series of nonperiodica! publications: The Applied Mathematics

Series, Circulars, Handbooks, Building Materials and Structures Reports, and Miscellaneous

Publications.

Information on the Bureau’s publications can be found in NBS Circular 460, Publications of

the National Bureau of Standards ($1.00). Information on calibration services and fees can be

found in NBS Circular 483, Testing by the National Bureau of Standards (25 cents). Both are

available from the Government Printing Office. Inquiries regarding the Bureau’s reports and

publications should be addressed to the Office of Scientific Publications, National Bureau of Standards, Washington 25, D. C.
NBS