NATIONAL BUREAU OF STANDARDS REPORT

2297

PEEFORf^MJCE OF A DSVELOPMEKT MODEL GENERAL ELECTRIC 3 HP

CONSOLE AIR CONDITIONER FOR VANS AND PREFABRICATED BUILDINGS

'by

Henry Karger

C. W. Phillips

P. R. Achenhach

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 hack

cover of this report.

Electricity. Resistance Measurements. Inductance and Capacitance. Electrical Instnunents. Magnetic Measurements. Apphed Electricity. Electrochemistry.

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

Technology. Length. Gage.

Heat and Power. Temperatme 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. Smrface Chemistry. Organic Chemistry. Analytical Chemistry.

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

Mechanics. Sound. Mechanical Instruments. Aerodynamics. Engineering Mechanics. Hydrauhcs. Mass. Capacity, Density, and Fluid Meters. Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifi- cations. 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 sk^s 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

NBS PROJECT NBS REPORT

IOOO-3O-U7OO February 20, 1953 2297

Performance of a Development Model 3 HP Console Air

Conditioner for ¥ans and Prefabricated Buildings

manufactured by

General Electric Company

by

Henry Karger

C« ¥* PhiUips

P* R« Achenbacb

to

Engineer Research and Development Laboratories

Fort Belvoir, Virginia

The publication, repi

unless permission 1st 25 , 0, C, Such pern

cally prepared If thi

Approved for public release by the ' Director of the National Institute of

Standards and Technology (N 1ST) on October 9, 2015.
COT4~Cf.>OOOX

ft .pXoa^'JoO 'tii £ :fe«sr3KjoXav90; s to

iinl -sns an^^V ro'l *£&i:foij.lo;:o:.;

^;ji£;^ajop .fl'i^cpXa IstsaoC

reg-ioX Y'lP'p--: .aaXXIiaa X'

.:2 ,-

Xl©t®^©^iT olev-Si-X ikiB £io*Si?i.?>0::a •tsyfiljiiia

v;,.Ti;¥ ^rXc/XoS ^'’XO'X
PERFORMANCE OF A DEVELOPMENT MODEL GENERAL ELECTRIC 3 HP

CONSOLE AIR CONDITIONER FOR VANS AND PREFABRICATED BUILDINGS

ABSTRACT

Performance tests were made of a development

model of a sectional, package-type, air con- ditioning iinit manufactured by General Electric

Company for the Research and Development Laboratories, Fort Belvoir, as a basis for further

development of air conditioning equipment for

vans and prefabricated buildings. Comparisons

of performance were made with the unit entirely

in the conditioned space, entirely outside the

conditioned space, and with the xinit divided

into two parts - the evaporator section being

mounted in the conditioned space eind the con- denser section in the ambient air - with a minimum of ductwork employed in each case. The

total net cooling ca^city ranged from 10,500

Btu/hr to 20,040 Btu/hr at ASRE Standard rating

conditions for self-contained units with the

capacity being 4 to 8 percent higher with the

divided installation of the evaporator and

condenser sections. Leakage of outside air was a significant factor that affected the dchumidifying capacity and total net cooling capacity of

the unit considerably. The performance factor

of the unit in Btu/hr/watt was lower than the

minimum value set in the Federal Specification

for self-contained air conditioners for normal

closure of the fresh air dampers.

I. INTRODUCTION

In accordance with a request from the Engineer Research

and Development Laboratories, Fort Belvoir, Virginia, dated

September 20, 1951^ tests of development models of two

sectional, package-type, air conditioning units were made to

determine their performance as a basis for developing air con- ditioning equipment for vans and prefabricated buildings for

Theater of Operation use. The two units were designed for

capacities in the range from 10,000 to 22,000 Btu/hr. This

report presents the results obtained on a specimen manufactured

by General Electric Company of Bloomfield, New Jersey. Tests

were made to determine net cooling capacities, the quantity of

conditioned air circulated, the quantity of air circulated

through the condenser, and the starting current of the unit.
JJli. SST.‘-

','; V

-'78.?-%:^;

.i : 4^:^'

'^

t

vyv*«U

f-£.%*i^i% AitSl^^ .A'^-

'5^

*1* . '., wtUmi ,?s0?''^^v t’l*

M^f* .-:^T"'- / ^' •iV.dJjgfi' *< ,t?’ ?>•> / y

If .. »'^“y^i')

:r silii ' '

'

V

7 ' ?f?(.iir ^Sihr^ ’'7- '.,;’\7:^ ;^'-v ',<.•*'

!»- 7v?r-' v^^j;r ^

^ •/ ---:4

- - ’

,

• '

’. ' cr

M-vrt" <<k " '- v“r^' ‘"'- •i^ny^f*‘: ~"7

•**v^ f,^- ;h,'. :

'

. >

.'-‘O v ,A^s -i-^^'\-'>iri:j; ^ .|«|\n'-i’.r-"r

' -a^*':'

'^,.. r'*i,''*7T^’C' .* r,>V ^!®’' Ti^iii^i* ' i' J W7?'.'y ,7. .7, -.4' - ;.ry» i,j.

•'

'lV:..'^’‘;'‘‘

L

' ' ' ’' lUf fcjf^^ . - "••' ''

‘•'r fcii:^, 44^^ -^.-r ;\v, j

i.'Uv. . 7' ,.*<Fs%'-#^^ ’J' .-./-il^ 'Hil '-^: ;\':>i»,-|^S'1

'.Vy-r ^.'7- ^"ai# 3£

! " ?i . .'

,

7*y<‘ f

-;Vfj ' •’^‘ifi^;*’' ftf ’^4' . -"v ' iUKt' iWll^»<>^ ;*#'!'• >!'4‘M; ij4'

r .1'.-.,'4 ; 7‘4 :r t. '

. -jt i‘(i> V

' ••. /'vJ'';'-; : . - i jf ^-ff- '•(*l^-.>.-. (,|;V ^ - vH
-2

Capacity testg were requested at standard rating con- ditions of the American Society of Refrigerating Engineers

with outdoor temperatures of 95 “F dry bulb, 75“F wet bulb,

and indoor temperatures of 80®F dry bulb, 6?^F wet bulb, and

at high ambient temperature conditions of 125 °F dry bulb,

85“F wet bulb and Indoor temperatures of 90°F dry bxilb, 8o*F

wet bulb.

II. DESCRIPTION OF TEST SPECIMEN

The specimen air conditioning unit was identified as follows:

(NBS Test Specimen 76-52)

General Electric Company, Bloomfield, N. J.

Model 2IFF20A1

Serial Number 21976976

The air conditioning unit was built for operation on alternating

current, 208 volts, 3-phase, 60 cycle> ^-wire. The sectional

construction of the unit permitted operation in three different

ways: the entire unit in the space to be cooled with ducts

connecting the condenser section to the outdoors; the entire

unit on the outside of the space to be cooled with ducts

connecting the evaporator section to the conditioned space; or the unit separated into two parts with the evaporator section

placed inside the conditioned space and the condenser section

placed outside the conditioned space. The sectional construction is evident in Pig. 1 to The bottom section con- tained the motor and compressor; the second section contained

the condenser; while the third section contained the condenser

fan. These three sections were not built for ready separation.

The condenser air entered the unit through the bottom section

and was blown out through two outlets in the third section as shown in Fig. 2. The fourth section contained the evaporator

fan, and the fifth or top section contained the evaporator

coil. Fig. 3 and ^ are views of the air conditioning lanit

with all the face panels removed^ and the five different

sections of the unit can be seen very clearly. The compressor

was of the open type, direct-connected to an induction motor

with nominal full load speed of 1725 rpm as shown in Fig. 4.

A centrifugally-operated clutch permitted the motor to start

without the compressor load.

The electrical controls for operation of the air conditioning unit were mounted on the third section of the imit, as can be seen from Fig. 1. The controls consisted of an off-on switch,

located in the center of the control panel, a four-position

switch located on the right-hand side of the control panel, and

a thermostat with its adjusting knob located on the left-hend

side of the control panel. The four-pOsition switch was marked

«i„, "3", and
'

Si •

" r.K
-3

-

According to the Instxvetlone furnished hy the auusufaetureOii

the unit should be started in the follovlng sequence. With the

selector switch in the Ho. 1 position;i turning the disconnect

switch to the "on” position would start the evaporator fan; then

turning the seleetor switch to the No. 2 position would start

the condenser fan. The compressor would start by turning the

selector switch to No. 3 position, and it would then operate

intermittently according to the demands of the thermostat of

the unit. If it was desired to operate the compressor on an

external control, such as a thermostat, this could be done

with the selector switch in the No. 4 position.

A knob, which controlled the position of two sets of

louvers, was located on the right-hand side of the fourth

section of the unit. The control shaft on which the knob was

mounted can be seen in Fig. 3» The two sets of louvers, one

located behind the fresh air filter and the other behind the

return air filter, controlled the amount of fresh air taken

in by the unit by opening the fresh-air intake and at the same

time closing the retum-air intake from the cooled space. \

Two centrifugal fans were used to circulate air through

the condenser, the fan wheels being mounted on opposite ends

of the shaft of the driving motor. A similar arrangement was employed for air circulation through the evaporator. These

assemblies can be seen in Fig. 3 A thermostatic expansion

valve was used as the refrigerant flow control.

The physical dimensions, weight and electricad data for

the unit were as follows?

Hei^t, in.

Width, in.

Depth of fourth section.

69

k2

including filter frames, in.

Depth of all other sections, inWeight, Including wood

l8-lA

14

shipping base, lbs. 646

Compressor Motor, HP

Condenser Fan Motor, HP

Evaporator Fan Motor, HP

Refrigerant charge, lbs. Freon-12 16

The unit was equipped with two air filters made of expanded

aluminum mesh at the evaporator inlet and fresh air inlet,

respectively. All framing and panels of the unit were made

of aluminum.
' i^') ‘

' i' ' ,1;''*

' J

' "V 1

yl- i»r

»• ^

':<p^.l <^r'^Xf:€ i^»|F v-'‘'-‘f|!piv^ yi:J^ t;o s »;/:, r!Vv(#?i ..'-\^'t^>r •' .'•:.;«i iA.!? ' .--1. -=-^3S:^w i.'t* ^

ii

J!iir 4vii^( >t;:'

.•'»> i'>\^

s^-i^ T‘^ lid : .d C: ^

1 ^ V V

'V.^cv ’"tX !'«.'> HI

j

'“f " x' ;''A>s’' '?' '-i'- ' ^-»|ft-

'4

'"ip

:-dm^

dP-3' i-'^'T^p-, ,'

•

' ';* ifftir »w' • , .. ““A

*-S>l v^.

. rf ,

.• .1

’

•

•• ,:V<:V ^

/ ' vf

i'^ V. •

vv'^'ia

rv'":';-’;'^.:^v‘^: „.;

dp:

' • ''‘‘ -. "ft • '..','f'''','' 'f rt’’
-4.

Ill . TEST PROCEDURE

Circular No. l6«R, published by the American Society of

Refrigerating Engineers, entitled "Methods of Rating and Testing

Air Conditioners", vas used as a general guide for the procedure

to be used in determining the capacity of the air conditioning

unit* This ASRE circular states that the capacity rating of

self-contained air conditioning units shall be the net total

room cooling effect in British Thermal Units per hour. The

following apparatus was used to determine this net room cooling

capacity.

A portable, 600 cu ft warehouse normally used for the

refrigerated storage of various materials was used as a calorimeter,,; For the fir*it series of tests the air conditioning unit

was mounted in the opening normally used for the refrigerating

unit for the warehouse. It was placed on the inside of the

warehouse-calorimeter flush with the outside wall. The calorimeter was then sealed in such a manner that only the openings for

the cdndenser air circuit and the fresh air opening communicated

with the outside space. For the second series of tests the air

conditioning unit was placed entirely on the outside of the

calorimeter sind short ducts were used on the evaporator air

circuit into the calorimeter. For the third series of tests,

the evaporator section of the air conditioning unit was separated

from the condenser section and was placed on the inside of the

calorimeter whereas the condenser section was placed on the

outside of the calorimeter. The calorimeter was sealed so that

only the fresh air opening of the evaporator section communicated

with the outside of the calorimeter.

For each series of tests, the warehouse, with the air

conditioning unit in place, was calibrated to determine the

heat transmission per degree of temperature difference between

the inside and outside, since this heat constituted part of the

sensible heat load. Electric heaters were placed on the inside

of the calorimeter to provide the remainder of the sensible

heat load for the air conditioning unit. A humidifier con- sisting of an electric heating element immersed in water was

also placed inside the calorimeter to provide the necessary

humidity. The calorimeter was made as airtight as was considered

necessary, and provisions were made to measure the amount of air

which was introduced into or exhausted from the calorimeter by

the air conditioning unit during operation. This was done by

removing air from or introducing air into the calorimeter through

a pipe by means of a blower. The air quantities were measured by

a pitot tube placed inside of the pipe. The amount of air flowing through the pipe was regulated by a throttling valve so that

the pressure difference between the inside and the outside of the
I ..' •. •? y X-t:.

:;,^^^ 'Xi? •.. .dy

rn V < I* ••' ' *•••', *

. ^ -i • • •• >»• •- '* T -‘.S

i^.£Tx -^r.. • ;

•’ ' •:

f

.. '. ^

•' w;, ^

•:, 1

'..1

'i.t t iiiy, ,;,A,o Av4?.A,:«4^ J 'C A

' A'; ,

1 * ,:'’

•’

, -^. -•v-^ m

•'rn '. ’'A‘

r*

'

• • ••

‘ v.^4 q-:*

• ;

;

•xj: '''

- .:

'*' r- -4^;;*^.'; ir^ ••• : .;•

*- y-v s *>: V.' ','‘

Jin A

' -,v v Ac.- " ,

’. m- ’• v-‘.”»^ »T’*' Vi-Jffltvtw

V, i;.-.v‘, sC’VS^&rfi'! -A

' ./(*n

41k;*’

,.

.

A

' .,. > A

' 7 /A A ;;:.,v a;.-, ;; :i 'A • • I .;

• ’'

. _ --»£

St

l*i*'.’> A?rl> ’ •A ', '•a 'AiA '7', rTM^M

> 4f .. ;,.' ;'5'iA c ^ ii;f'5;

. y.

,

> ,74 ® . A \v(^

^

-‘iAA , ,.:>«

ynyy'i 'iXfiz Aa. ' fcr' '? " V,- '^v:^

. :wfA ^4'; it;: 'A • '*2A

' aA'.:- A-r^f,.;; -'-•"'-A'

A. .. .

'. .

• . •' j;? j»- nr i> .. .

• ;% <^'g •'A.v iittfiwa #

.'

•. .-f-Ui'i '. *•'.1^ >:;tjis^^4^jpj||p- V'3.

• n. >A

'K.^A.::.C:njfc«;a.
-5-

calorimeter vas zero ± 0.002 In. W.G. Calibrated vatthour meters

vere used to measure all electric energy consumption. Temperatures were measured by means of calibrated thermocouples using

an electronic, constant-balance type potentiometer. Humidity

measurements were made utilizing calibrated lithiura-chloridecoated elements In conjunction with a micro-ammeter. Humidity

measurements observed with the electric hygrometer were checked

regularly with a 2k" mechanical psychrometer . The condensate

drained from the evaporator coll was collected as a check

against the amount of water evaporated by the humidifier.

Measurements of the quantities of air circulated by the

evaporator and condenser fans were made by means of a pitot

tube located Inside a smooth, round duct during separate tests

with the air conditioning unit removed from the calorimeter.

This duct was connected to the outlet of the evaporator or condenser air circuit by means of a plenum chamber and an

exhaust blower was attached to the other end of the duct. The

air flow through the duct was regulated by a throttling device

so that the static pressure at the evaporator or condenser outlet

opening In the cabinet was zerd ± 0.002 in. W.G. with respect

to the pressure in the test room to determine the free-air

delivery of the fans.

IV. TEST RESULTS

A. Cooling Capacity

Determinations of the toted net cooling capacity of the unit

were made for two different sets of indoor and outdoor temperature and humidity conditions, for each of three different

positions of the unit with respect to the calorimeter. Tests

la and lb were made with the unit entirely within the calorimeter,

tests 2a and 2b were made with the unit on the outside of the

calorimeter, and tests 3a and 3^ vere made with the unit divided

as previously described. All tests except test ha were made with

the fresh air dampers closed, but not sealed. Thus the enthalpy

difference between outdoor and indoor temj)erature conditions for

any air that leaked by the damper in its closed position or through other openings in the air conditioner was not credited to

the total net cooling capacity of the unit. A single test,

numbered 4a, was made with the fresh air dampers sealed to

determine the cooling capacity of the unit under these conditions.

For this test the unit was divided, as for tests 3® an<i 3l3» The

desired test conditions, the average temperature conditions

maintained during the tests, and the results are summarized in

Table 1.

The total net cooling capacity, as shown in Table 1, is the

sum of the net sensible and latent cooling effects. The
• .,S'

m

. -V. '.«!.:

;.' . %•' ’'^*1 -i^it .' ..^‘^v.^' jy|; 4

'-, r ' :v .

• .:^rvf^.7

^: '-.'

"’f ‘^:?:/5Cy '• C' f-.P^ * ;..

. . t'- ^-yt,--^. --iij Vi^/ ^i^-,./.V‘v’-‘f;:'>^’'i; ;i'-'Z,;-3-k

X. ... .$a ‘sfe ,'C

i*

:;i,;K : ^ . 4' >

.:; psr:'-; ' iX./^ ’k

: .U! . .•». ^- / -.i } a. r; tiy JS*?'n;v ' ^ ;)( " -jfe^ .Sk''

•»V : :X x

,fi-,jr: :.- i| i^ i(«i|i^i!s^'»;-,i

'

ii'J ':%#'

' -'

/V'ji..; v.-;, -,•

^

< ...=-v

m'

'A-'

'•• >/Vi-'v. ..-.•^

tf'X

KJX

r- : »:•

,. ,

. ' T' XvC- ^

^ ;*r:iyu

'

,•>>>:. t^' f

..^ y

'' im M

i' >-' «' .i '* .Jj y>.»flijN -' v-V >^j^7 ;

.' '.''-r'i^, '1 '- ......^

-V;.. . '‘iC’. a

,k;‘ - yri.r*'' i’ ; •-/ '

.

• ¥ -^ . ..•^ ._

-• • •y«^£>g5’ ^'f,- .:
-laU

Qia

o

•H-P

CloO VO

tcvj lA

I

o

u

0) a<

d ra H d d

< 9J o

a •H U •H 43

•Hd o

43 d H O w o

CD o

43

pq ra ^ H CD Eh cJ •v Eh d H

O •3 d O CD

CVJ d

•H

ra H (U c OJ R

fl) H

o <U©

CO

lA LA O CU 00 OJ Q O lA^ OVCO.VO j

5

Id

i^H

lo

l-p

Is

Ira \S

I

a

-do3 CO

LA LA O

OV

O HI

CO VO LA OJ

to Id

O Pt, Ct< M » o >»

,-P +3 M •v iH

PQ » • fQ '= i-i-a

+3

<U d

o

"Sa

cd H

-d- O LA COCO LA CO

• « • 9 9 9 9 CO -d- P^CO CO CO

CVJ CO CVJ CVJ 00 OJ LA H H H

LA LA H CV) CO CVJ H

O CVJ O • • • LA-:*- CTv

CVJ CO H

-d- 00 O

ON C^LA

CO

9 CO O• • -d- CD On

ON C^-d-

-d- CO On

ON C--.dO O CVJ • • 9 CJN ON LA CO t-~'sO

LA NO

• • LA CO

t-” t-~-

CVJ-d-O CVIOO CVJ OOOO 00-d- CO VO ON

CVJ CO H H

t-- lA

vO -d- CO

CVJ CO H

CVJ LA On o LA CO 00 VO

VO LA

00 CO LA p- CVJ p-lA Q o-dONOO VO

On

P~

-d- P- O -d- lAOO ON H H CVJ VO O

C3NVO

C7N r COH

CTNVO O

C^vo LA

ON CO O • • • tr- la

ON 1

LA CVJ CVJ CO

ONHH

O P“ H

CO 'i> LA

P— LA LA H O LA ON -d- P“00

H O H

O CO -d- H

CO

CVJ H

O p- H

CO VO LCN

O PVO LA

CVJ 1 9 ( CO I VO I

CVJ I « I -d- • VO I

LAOO O • • • +J LA LA H CD ON p--d"

c3> (x< IXf "N W <3

lO

IC

1«

Id)

.•H '•§ \<

+3

o5

raao

•H

+3 _ _ ..:3

m m -p c

cS O H O OJ K Sh

p|^ I • 9 PQ &i-a'

0) (D B E-» 31

W.

m PQ >»-p d CD Q :s

>1

•ri

>»+3 H

fci 0) (U R «l

I

os

+3

ra

(U EH

raao

•H

+3

§o

h

+3d

<D •H

'§<

pL^ pL4 A O fo fe

0 0 >> O ® ® +>

• • *0

Oi Oi nH s a s

QJ OJ d B E-I W

pq PQ >>-P d (D R :3

+3

OS

rad

o

•H

+3d

oo

LA CVJ LA +3 P- 43 CJNOO C*“ CD LA I VO VO ON H CO H C3NVO O +3 CVJ i ONP“C043CVICP-VOVA^JVO t O

U

O

43

a)U

aca > pt, fe »» > fe {j^ woo W o o -p

d 5 H H o

d

d d O

OJ © 43

ra ra cd d d d

<13 ^ <13 O '^3 ”^3 CU d d

4^

•V 9V «H

9 9 fQ

9^ Qj -g

>» O

d

«J (D EH EH

PQ PQ >»+3

d 0) R rs

•*43

• cd a

a

CD EH

rid

rado

•H

'R33

PQ d

>» o

R d

•iH <a

CU CU>H a a

? 3

PQ PQ >»43

d CD R ^

3

m

(D>

•H

43

CS HOJ K

rado

•rl 43d

oo

PU PU a a 55

3 3

PQ PQ

R :s

- 

-

0\ P UMTN cn H C3NCO O VTN o o O GO VO o o

fit LTN o ro • 0 • Q • • If^ ‘ p o p • ro VO cn c*- ro-d- I/N H t- m cy i/\ lA HCO CVJ ON cn CM OO • 00 VO m H 0\ CM lA p-p

CA lA CO

-sf P VO OO LA p ONCO VO p o o O LA LA o o

fii t- c> t— LA • • • Q m-d- VO P CO CM J- p

C7N O

VO

-d* • LA -4* ON • VO o CO

CM co • o ON VO CO fH ON P * ro CM CO CM LA VO CM LA m

p

cn VO 00 p

cn LA p

m On CM ^ O OGO ON LA o o o m m o o

fit GO o o-vo • • • o VO CM OO p CO • lA VO

p CO VO P CM • P On VO lA ON -d- VO • LA p ro -d- p CO ir\ CM lA CMp

m VO t- p

m LA p

CO -d- fA LA on onco On cX5 o o O VO LA o o

o3 CJNCQ LA • • • o

VO CM^-d-COvO onCM

CM on

VO LA p • CM LA • VO LA

-d" • • CM CM 00 -d- o P on p 00

CM ON ECM 00

CM

« VO

VO

CM

o

lAvO Q (On O On

P CM ONCQ

ON • • o O

00 o LA o o O oO OD o o

P LA CTN » CJN LA -d • LA p o

on-d- LAOO £*” OnCM » e WGO tp CM O on « t- 00

CM on P on C5NP on 00H

p O ON

CM

iTv on on I

lA-d- on CM O P OCO LA o o o ooo o o o

ON P On o • ® O LA LA ON on 00 p • o p o 00' on^ ON CM • • on ON o ON lA LAVO • CO

CM on o on CTNP-d- t-pCO ON

p

LA on on

cnco 00 o o o\c

ce VO O • «

H CO PO-d- VQ OM>- m<

OJ rO

CO§*= =

CO

CO •pp

a

“S

(U

(U p

p LA <U P c- s lA

o

ON

o

00

OGOo o

00

oCM

• • p iH ONO ON iH P on 9 On on p on o

P-d- fto

. *> p

cH ON ON

p

lA on CM

(U p

«H

p

cCo o

p

au

S.'d

op

a

ta p

CO

>» p

p

u

0)Oia S30 bOP

p

p h

c3^*>0

Oi P

A

>* p

05'^'^

ft 0

03 P

P

>> pp

o

cd U

ft J3 c3^^ O 0

p

o

ss; pCO

(U

0 fH a <U (U tsO pj a PP O pq o pq o P bO pq pp

•V U o o to 3 > O G •H •H p fn' G •d 0 O fH fH p p p (U G O to •» p bO bO p O 3 P d

O +> O O fH Q = <u p 'd P ft 0) o G G cd p p ^ > P o p fit o 2 bO p (+H O P fj O p p K o pp «ft Q

s O o p o3 CO 4-1 U P •» 3 o p cd a •V ft s s O Cl p <0 o p >d d to Cm o p ft d d u

S fH s c(3 = p o3 Tf G G h to d p o cd p ft p

0 O a a ft p O <D P o 3 d p •d o d d a <

ca (0 <S3 oi fH fi > p fit (U o to jh p p n d 0 fit a w ft ft o fH o . (d fit fH to ft p s p G p cd d

o a to (U fit H 0) fH u •H ^ d to 0 d d 3 d d bO O Ih « • p to to 03 O fi o (U p G p ;z: p a p w cd ft ft x3 c(3 0) c u a 0 ft p ft o d d fit fH M fH S 03 a fit fH o o P P 03 p p p ft Q p p o p p ffl 0) o > o o ft >o ft s to > o to >> »d p cd to p cd cd d > o ft O Eh B C! o3 fH p ft o d fit CO'' t) fit fit p G fH fit p p

O o O > a? o fH d 0 d d o d d o o

ft O O ft E-I Jt, ft m ft iz: s EH ft ft Eh
' /

•A Iv

i i3^

^^r %

fa

-er. ^ to

•yti A/? sc

cvCO

U’i

t). V-.

t;.

'*
-8-

discrepancy between the amount of water evaporated, in the humidifier and the amount collected from the evaporator coll was due

to the large amount of leakage air introduced into the calorimeter

by the air conditioning unit. The additional water was extracted

from this fresh air. The amount of air leakage was variable

between tests depending on how securely the fresh air dampers

closed in respc^sse

^

the control lever.

A comparison of the total net cooling capacity for inside

and outside mounting of the air conditioning unit in Table 1

shows that not much difference in capacity was obtained for the

two conditions . The inconsistency between this comparison for

the high and low ambient temperature conditions is probably

accounted for by the variations in fresh air leakage. Higher

leakage was observed for the outside mounting at the lower

ambient temperature condition whereas the reverse occurred at

the higher ambient condition. A computation of the probable

heat transfer from the condenser section cabinet (consisting of

three parts) and the evaporator section cabinet (consisting of

two parts) indicated that the total net cooling capacity should

be about 800 to 1000 Btu/hr higher with the unit mounted outside

the conditioned space. This apparent advantage of the outside

location would disappear, however, if condensation occurred

on the evaporator housing in the outside location or if long

connecting ducts were used.

When the unit was divided into two parts as for tests 3a

and 3I5

, the total net cooling capacity was increased from U

to 8 percent at the lower ambient temperature and from I9 to

23 percent at the higher ambient temperature. The major portion

of this increase is undoubtedly due to the fact that with the

divided Installation heat is not transferred from the condenser

housing to the conditioned space nor is heat transferred from

the ambient air to the evaporator housing. When the evaporator

section was mounted on top of the condenser section, only a

sheet of aluminum approximately 3/16 in. thick separated these

parts

Test 4a, made with the fresh air dampers sealed, showed an

Increase in total net cooling capacity of 2930 Btu/hr as compared

to Test 3a> made under the same conditions except for sealing

the fresh air dampers. This increase in capacity should be a measure of the effect of air leakage through the unit when the

condenser and evaporator sections are divided as for Tests 3a

and 4a. It is of the same order of magnitude, but somewhat

less than the computed total heat removed from the leakage air

shown for Test 3a in Table 1.

It will be noted in Table 1 that the computed value of the

total heat removed from the leakage air is less for tests la,

lb, and 2b than the difference between the total dehumidlfying

-9

-

capacity and the net dehutnidlfying capacity even though this

difference is only a part of the total heat load caused by the

leakage of ventilating air. This inconsistency Indicates

either that there was air leakage into the calorimeter in

addition to that removed by the auxiliary blower used to remove

leakage air from the conditioned space or that the . total heat added by the leakage air was actually greater than

that represented by the ambient air conditions and the conditions

at the inlet to the evaporator. Leakage of air around some of

the cabinet panels of the condenser section could explain this

discrepancy for tests la and lb.

Computations of the net sensible heat removal from the

conditioned space based on the air circulation rate of the

evaporator fan and the Increase in dry-bulb temperature

between the evaporator section outlet and inlet openings do not

agree exactly with the values of net sensible cooling capacity

reported in Table 1 derived from the calorimeter measurements

using watthour meters. The computed values ranged from 8.1

to l6.1 percent higher than the net sensible cooling capacities

reported in Table 1 for the seven tests. This discrepancy is

probably accounted for by the fact that in many air conditioners

it is difficult to obtain an accurate weighted average of the

discharge air temperature because the confined conditions in

the chilled air circuit make it improbable that a uniform

velocity and temperature distribution can be attained at the

evaporator outlet. A part of the difference between the com- puted and measured net sensible cooling capacities may result

from the fact that the evaporator air circulation rate was not

measured during each individual capacity test, but was determined

in a separate test.

The electric power consumption of the air conditioner

appeared to be rather high for the net cooling capacities

observed. This results in a low performance factor in Btu/hr/watt

as shown in Table 1. For tests made at ASRE standard rating

conditions (ambient conditions 95 DB, 75 WB; room air inlet

8o DB, 67 WB), Federal Specification OO-A-372, covering selfcontained air conditioning units, requires a minimum performance

factor of 6.0 Btu/hr/watt for console-type air conditioners

with air-cooled condensers, such as this unit. The unit reached

this performance factor only in Test jfka. during which the freshair damper was sealed.

Table 1 shows that the sensible heat ratio was above 90

percent for the tests at ASRE standard rating conditions with

51 percent relative humidity in the conditioned space. This

result indicates that this unit would not be able to remove

very much moisture from a space at a humidity level of 51^

and suggests that the evaporator surface was not being effectively used. The Federal Specification for self-contained air
sV .- .<JT^Vv-/v '-'»

t* .•’’^^^^‘ "W" • ,-' -

' "^- '*•

'•*'•*'- •'•i. *^S« 9$^ ^i^.ilim

'.^ ''J'*- rf» V 5^'

tM . ;5T,:jon ^

-M wm---

-^Tv , %

^

'iH^vrf »Xr.X. .'^'fX '^|g '

'

. ,: €'c?o'^^ttfj«i;'w Xcfi^'iyu .-figSj^ ^ ^ .t>

. X-rxXjf'

•

': 39 \.X^=>‘i i' ^ .’ .•if?X 'iS .: -’X?X

i-\it ,,<;,v :-^:;?rK‘,:!X;X,i’ -*.fijA:iffi •.••V'"i>^Xifl#

' •• f<vi X,. V vX# H . ’'f^^

.vtX-. XX ' :^:v ’^a

ifj

r.;.;;;^, h''^

^ aCvl-fcfe -.‘v* , £

*"‘

4

.’.- >.'X'

' •’. .'i-X-‘' »' m ;7U Ofc,/Vr^

'Hi'"-

. -v’i^ iS?x^'<v:;.^*.>cs^j|jjA XX'oc'j i\

4‘X^it .3' :, '’X'‘',-’-’

' 'iAX. “ -.J^rx «Wi «msfW'“'^•'

X«:;7^ / __ .xr<'3X-^ -y^'i

'.^ ^!' rl*^

' ':' ::

' "..

;

"• "^,

' Xu --\ ^ ivUs^irx ':< x^'X, •.c,.^

;•' J^IX »« •• ,;:,<

, x.^ . X,;;..;,

iXx i.»:il£- :X: x.rx £x./cp» «?

• T ;.'>•' 4:: '-“^r. X’.ii

' '' ,. '. V

>!‘ ':.

A'V'3 *TVs> i* >':,U'v<4.*

X^l .'

i‘j
-10-

condltionlng units requires that the sensible heat ratio be within

the range from 70 to 8o percent for these room conditions.

B. Air Circulating Capacity

Determinations of the air circulating capacity were made

for both the evaporator and condenser fans. The results of

these measurements are summarized in Table 2. Federal Specification OO-A-372 for self-contained air conditioning units in

this range of sizes requires a minimum of 30 cfm of air circulation per thousand Btu/hr of rated capacity. The amount of air

circulated through the evaporator and condenser exceeded 30 cfm

per thousand Btu/hr of observed capacity.

The ventilating air that leaJsed through the air conditioner

with the dampers closed but not sealed was measured during all

capacity tests. As shown in Table 1, the leakage ranged from

66 to 93 cfm. The latter amount is more than 10^ of the total

air handled by the evaporator fan, and the loss of cooling

capacity caused by this unwanted air can be seen by comparing

the net and total dehumidifying capacities and noting the

computed total heat removed from the leakage air, as reported

in Table 1.

TABLE 2

Air Circulating Capacity of GE Unit

Air capacity Temp, of air during

fan tests

cfm °F DB °F WB

Evaporator Fan 881 79 58

Condenser Fan 1004 78 60

Federal Specification OO-A-372 requires that air conditioners

be equipped with provisions to admit 5 cfm of fresh air per 1000

Btu/hr cooling capacity. For the unit tested this would amount

to about 100 cfm of fresh air or only a little more than the

leakage air observed on this unit. Thus the heat load caused

by the air leakage should probably not be considered as totally

wasted capacity, but should be viewed as an irreducible minimum

whereas the fresh air dampers should permit adjustment of the

quantity of fresh air below as well as above the value of 5 cfm

per 1000 Btu/hr of rated capacity. The two interlocking sets

of dampers on the evaporator section permitted adjustment of the

quantity of fresh air from the minimum values shown in Table 1

to 100 percent fresh air.

C . Electrical Tests

A Brush oscillograph was used to measure the instantaneous
*• '#-'«

S-

: .;; :--!j,\-^-v .'v?^ ‘/i* • . ''f*' :-,'

.‘:-)K|fe

:f

' - -c ::'; -^Cv'

'

* v||: ./«J|

.1 'V :- v; ^

.i; -&:x; V'?

-’ .^•*5

*' - •' "‘^}- b m r':

\-/^p..y^:i '^^ry qji.1 '"Hi :' [M ' *!|«

:;; /

•fv F> f\ '" ’ •''^' * • -.^'••. • t- ^ ,. ,

' '. IdP '

• if-''.: >v : .'.f^ ;• .Vjii;

' j- '‘4l H3 .. ^T

IPS

J3(-

'

, Vv‘ . .

-Hi .

• i </*qi;VT3> t

fiAi S 4b i(f:..^^<fRis^ '

"4V”:''‘> r '/: b ., qr-b'-''- i4;br?i:»,Jgb> -

. ^; -

' '

PI • 'r -T. ' ^

'

• .

P"::’

' ' '

'

• O' Hj-A A'L -; ^c'-;

, ;-o.ib

<51? X 'X X''b- /• i:?05 ,'K' -Q.'. i o#

AaP'^AM

'*' '••'<? xoW'f . Ahik, a ?:<•*•! X

%•'••' ••.«J|f/»*-’ • ;* v

' o' 'r >.'•

'

. 0 .;• b.:, ;iXy«vO ^ ;: • Or ' •• • ’'' '"Ol^fe/f''

,•

; vJol^'^r 0ir',O;S£%-^ /’i';‘< : V

• .:;s05«;,'< O-' 0:0.:*' C5^ 0>:-i 'C'W ' -0 0'-:^ y >i' :-0 • •- -t:vr..vvi*?X^i-0;i^

fx.-!; iH ‘fx/**’.

.r‘-^^#v^.'

• ^t;.,

.

• I,' .1 • • ' <''. ..*^ 0 *' ir"-"!' or': ’^2WrOVi:(sV>.<JiO

\U .'u " '>

'

' - O^\> tw
-11-

starting current for the entire unit and of the evaporator fan

alone. The highest current observed for the entire unit was

166 amperes, and for the evaporator fan, 56 amperes. The time

of starting was 0»25 seconds for the compressor and 0.52 seconds

for the evaporator fan,

D. Construction Features

To permit checking the amount of condensate drained from the

evaporator coil in relation to the amount of water evaporated in

the humidifier, the condensate drain was connected by means of

rubber tubing to a receptacle outside the calorimeter. It was found that, as submitted, the condensate drain was connected to

the evaporator fan which of course would put the condensate back

into the evaporator air stream. This condensate drain should have

been connected into the condenser fan, and representatives of

the manufacturer stated that in production this error would be

corrected.

The ptHmary thermostat furnished with the unit was equipped

with a capillary line too short to permit mounting the sensing

bulb in its intended place in the return air stream. According

to the manufacti&irer this would also be corrected in production,

and before the tests were completed a satisfactory thermostat

was furnished.

During the testing of the specimen, the silica gel dehydrator

installed in the liquid line gradually became restricted, making

it necessary to re-run several of the tests after replacement

with a new dehydrator.

Each time the compressor was started after extended periods

of shut down severe rapping or knotsklng was noted in the compressor.

This was believed to have been caused by slugs of oil entering

the cylinders. Although the knocking was considered extreme

the compressor did not appear to have been damaged during the

course of testing. The knocking did not continue more than 10 or 15 seconds after starting, and the severity was dependent on

a number of variables, length of shut doWn time apparently being

the most significant.

Erratic expansion valve operation observed during some of

the first test runs was traced to the gradual plugging of the

dehydrator. No expansion valve difficulty was observed after the

new dehydrator was installed and the original power element,

which had been replaced in investigating the difficulty, was reinstalled and operated properly.

Head pressures observed during the tests at high ambient

temperatures were excessive, according to a representative of

the manufacturer. Under his supervision the unit was discharged.
ri. :U -:''l ^:n,uh- 'jj^-- ' «' »

^ U..-‘- rlp: iiX^-:^ ,»£S. SSO

'j,. V- f-’?

‘ r.: '*,;/ i^lll

my av> . d,^:-;.; rv. -3/#5 .,; t v H-! .'

' •^?

•'

/ivji :.' ti::^;’^:.-.-'' ^^^^.r ,,^ \:--^r r ^

;''^^‘a

* •fo .ty’/iV^ vif /,^^ oSlvSX^KMi^ <j 'f 4 V'

'

>' 1

* n

•fC v ,

'

• .' -• •:..

.

• sA*>:r ';I

- -r

' k * '^r '‘'i ' 5" '• ',-^. I

•’ .-'

‘i

•

'

otnJ' Vni- 1

:.'- n »- t.{S/,:':; y i, '

iit' S’ ;;: t«

‘ivJ'tiAX-:--'. ,' 7idXiv:.c,-<X 4i<i,P

^

:^-y : -P;,

-; X5- "u

-'•'• .'JT a: riit]> > .', : -v:*<3 wlA P -i-

.>.1

:<j

'>y

*t^W,i ..’^. Q

^*. . v ^;.:, o

' '--:/ i;-',- ;.- p,:;-‘ r

p

:

. 4';^

: '• :;P'r : rpp. riOilo^P -V- O'^ :

>.‘r't 'iti

'

• jX'.''

.i, :? i .;^, " ?7-'

'

Xns , if <*.&

, ' O

-' A - Wa:.;! f. i)

VtV ^

•••

i

' i ; f.‘>a. i : ,vip, —

k

. ..

‘mI W‘' • ’•uX
-12-

evacuated and recharged, hut no appreciable change in operating

head pressure was observed following this procedure.

Several spot -welds which attached the grilles to the

condenser air inlet opening broke loose during operation and

instrumentation of the imit.

V. DISCUSSION AND CONCLUSION

The results of these tests show that the total net cooling

capacity of the air conditioner was highest when it was divided

sectionaJJ.y, i.e. the evaporator section in the cooled space

and the condenser section outside of the cooled space. The

reduction in capacity caused by mounting the entire unit inside

or outside the conditioned space would probably exceed the 4 to

8 percent difference observed during the tests if any appreciable amount of ductwork was used in either the condenser or

evaporator air circuit.

The performance factor of the unit was below the minimum

value used in the Federal Specification on self-contained

air conditioning units when it was tested with the fresh air

dampers in the closed position. Consideration should be given

to redesign for tighter closure of the fresh air dampers to

permit better control of the quantity of fresh air.

It should be noted from Fig. 4, that the evaporator fan

pushes the air through the evaporator coll rather than pulling

it through as is a common type of construction. Pushing the

air through the coil in the confined space of the evaporator

section may tend to channelize the air and reduce the amount

of coil area effectively used for heat transfer.
I

-'ilB

-SJ-

-Sniidi. dost Jbiiij i(y:'

3ii5W 9*£i)339"iq b£.jL
NBS

FIG. 1

Fin. 2

FIG. 3

FIG. 4

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 structinres; 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 appfied 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 pubUshed papers and reports. Reports are issued to the sponsoring

agency of a particular project or program. Puhhshed papers appear either in the

Bmeau’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 commimications throughout the world. There are also five series

of nonperiodical pubfications: 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,

Pubfications of the National Bureau of Standards ($1.00). Information on cali- bration 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 pubfications should be

addressed to the Office of Scientific Pubfications, National Bureau of Standards,

Washington 25, D. C.
.

r-.