NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT

1003-20-4891 May 5, 1959

CAPACITY TESTS OF A REMOTE AIR-COOLED

SIZE B, CLASS I REFRIGERANT CONDENSER

MANUFACTURED BY

THERMO KING CORPORATION

by

F. J. J, Drapeau and C, W. Phillips

Air Conditioning, Heating, and Refrigeration Section

Building Technology Division

to

Mechanical Engineering Division

Headquarters,

Quartermaster Research and Engineering Command

NATIONAL BUREAU 0' intended for use within

to additional evaluation

listing of this Report, ei the Office of the Directo however, by the Governi

to reproduce additional

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

or progress accounting documents

is formally published it is subjected

ting, reproduction, or open-literature rmission is obtained in writing from

. C. Such permission is not needed,

sally prepared If that agency wishes <NB^

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

CAPACITY TESTS OF A REMOTE AIR-COOLED

SIZE B, CLASS I REFRIGERANT CONDENSER

MANUFACTURED BY

THERMO KING CORPORATION

by

F, J. J. Drapeau and C. W. Phillips

1 . Introduction

Capacity tests were made of a remote air-cooled refrigerant

condenser^ Size B> Class I, manufactured by the Thermo King

Corporation of Minneapolis, Minnesota, This specimen was identified for testing purposes as NBS I78-58.

The tests were made with an apparatus conforming in most

details to that described in the proposed ASRE Standard, PS 2.:4,

for remote air-cooled condensers. This apparatus provided a

means for measuring the heat transfer capacity of this specimen

by the psychrometric method and by the refrigerant flow method.

2. Test Procedure

Capacity tests were made at two values of saturation temperature of the refrigerant vapor entering the condenser, following the procedure and test conditions set forth in ASRE PS 2.4.

At the higher saturation temperature of 130°F, tests were made

at three air flow rates; namely, at the free discharge capacity

of the fan, and at one lower and one higher value, ranging from

2950 cfm to 4100 cfm. In addition, one test was made at the

high ambient temperature of 110°F, established as a standard for

QMR&E application.

These tests are a part of a series of tests planned under

the Condenser Standardization Project, QMREL-M P.O. 57-26, to

determine the possibility of standardizing air-cooled condenser

performance on the basis of maximum overall dimensions and minimum air flow rate.

This condenser was tested with a Torrington propeller fan

with air delivery capacity meeting the minimum requirement of

the QMR&E Purchase Description dated March 22, 1957. However,

- 2 -

this condenser did not come equipped with a shroud or bellmouth

orifice plate. To facilitate the tests, these parts were fabricated by the Sheet Metal Shop at NBS . A bellmouth radius of

approximately 3/8'^ somewhat less than the QMR&E established

minimum of 1/2"; and an orifice diameter varying from the QMR&E

specified value of 24 1/2" by not more than ± 1/8" were constructed for the tests.

3 . Test Results

The results obtained and the dimensional data describing

this condenser are attached. Fig. 1 indicates the shape and

tube arrangement, and uses letter symbols to identify the dimensions of the specimen as summarize .I in Table 1. Table 1

describes the materials and construction of the condenser and

lists significant dimensions of coil, fins, and complete unit.

Table 2 summarizes the test data and the heat rejection

capacity ratings and heat transfer coefficients computed therefrom. Fig. 2 is a pressure-enthalpy diagram labeled with the

symbols used in the proposed ASRE Standard, PS 2.4. This diagram Indicates the changes in state conditions of the refrigerant occurring between the condenser inlet and outlet.

In order to provide a further means for comparing the per-,

formance of the various arrangements of' tubes, tube arrangements,

fins, etc., of the several condensers in this test program, two

additional coefficients, which can be considered as Items 24 and

25 of Table 2, are as follows:

Item 24 Heat Rejection per Unit of Total Surface Area per

Degree F Log Mean Temperature Difference, Btu/hr

(ft)2(»P)

Item 25 Heat Rejection per Unit of Total Surface Area per

Degree F Log Mean Temperature Difference per cfm

of Standard Air, Btu/hr(ft )^( °F) (cfm)

-3-

Addition to Table 2

AS RE High Sat'n. Temp

.

AS RE Low QMR&E High

Item High Free Low Sat'n. Temp. Ambient Temp

Discharge

24 7.77 7.18 6.74 5.81 7.30

25 . 00207 .00207 .00250 .00175 .00230

It should be noted that the heat rejection capacity of this

condenser at the QMR&E High Ambient Temperature conditions was

102.5 percent of the required value of 35^600 Btu per hour.

USCOMM-NBS-DC

_____

COND^N^ER

SPECIMEN

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CONDENSER SPECIMEN

MFR. Thermo Klnpc. Coro. size-'q

^ NBS NO. 178-58 CLASS - 1

ITEM PROPERTY REMARKS

COIL TUBE CHARACTERISTICS

1 MATERIAL CoDDer Tyoe L

2 NUMBER OF ROWS DEEP 3

3 NUMBER OF TUBES HIGH 26

4 NUMBER OF CIRCUITS IN PARALLEL . 3

5 NUMBER OF TUBES PER CIRCUIT 26

e TUBE DIAMETER , 0. D. , IN. 1/2

7 TUBE WALL THICKNESS , IN. 0*042

B TUBE RETURN BEND DIAMETER ,O.D. , IN. 1/2

9 GAS INL E T CONNEC TION DIAM.,O.D., IN. 7/8 1 !0 LIQUID OUTLET CONN. DIAMETER, 0.0, IN. 5/8 . . II VERTICAL TUBE SPACING , IN. 3 1.3

12 PRIMARY SURFACE AREA , SQ.FT. 23.2

COIL FIN CHARACTEISIZTIC^

1 / MATERIAL Aluminum

2 TYPE OF FIN Flat Rolled Collar

S FIN SPACING , PER INCH . 8 .. 191 Fins

4 FIN THICKNESS , IN. 0.015

S SECONDARY SURFACE AREA , SQ.FT. 238*3

• COIL DIMENSIONS

! FINNED HEIGHT , IN. K .32.5 . 2 FINNED WIDTH , IN. F 27-0

S FINNED DEPTH, IN. V 3.0 I A COIL HEIGHT , IN. H 31.9

• S COIL WIDTH , IN. W . 29.5 1

i 6 COIL DEPTH, IN. D 2.0 1 7 COIL DEPTH , OVERALL , IN, N 10.8

6 FACE AREA , SQ. FT. 6.2 1 9 TOTAL SURFACE AREA, SQ.FT. 261.5 i

j OVERALL CONDENSER DIMENSIONS

/ WIDTH , OVERALL , IN. A 32.5

2 WIDTH , SHROUD , IN. fl 27*5 Manufactured bv NBS

3 HEIGHT , IN. C 34.-1

, 4 DEPTH , IN. E • 0 1 i

11— 11—

1

\ S BELLMOUTH ORIFICE DIAMETER , IN. A 24.5 Manufactured by NBS ; 6 BELLMOUTH RADIUS , IN. R . 3/8 Manufactured by. NBS '

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