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UDC 621.56/.59 : 621.51.001.4
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IS0
IN TERN AT I ON A L O R G A N IZAT I O N FOR STAND AR D IZATl O N
IS0 R ECO M M EN DATI O N
R 917
TEST IN G OF RE F R I G E RANT COMPR ESSORS
1st EDITION
December 1968
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
to be obtained through the national standards organizations.
Also issued in French and Russian. Copies
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La Recommandation ISO/R 917, Essais des compresseurs pour fluides frigorigènes, a été élaborée par le
Comité Technique ISO/TC 86, Froid, dont le Secrétariat est assuré par la British Standards Institution (BSI).
Les travaux relatifs à cette question ont été confiés au SousComité ISO/TC 86/SC 4, dont le Secrétariat
est assuré par le Royaume-Uni. Les travaux commencèrent en 1960 et les “Recommandations pour un code
international d’essais des machines frigorifiques”*, publiées en novembre 1957 par l’Institut International du
Froid, servirent de base aux discussions. Les travaux aboutirent à l’adoption d’un Projet de Recommandation
L ISO.
En mars 1967, ce Projet de Recommandation IS0 (NO 1154) fut soumis à l’enquête de tous les Comités
Membres de I’ISO. I1 fut approuvé, sous réserve de quelques modifications d’ordre rédactionnel, par les Comités
Membres suivants :
Allemagne Grèce Roy au me-U n i
Australie
Hongrie Suède
Belgique
Italie Suisse
Canada Nouvelle-Zélande Tchécoslovaquie
Chili
Pays-Bas U.S.A.
Danemark
Pologne Yougoslavie
France R.A .U.
Aucun Comité Membre ne se déclara opposé à l’approbation du Projet.
Le Projet de Recommandation IS0 fut alors soumis par correspondance au Conseil de I’ISO qui décida, en
décembre 1968, de l’accepter comme RECOMMANDATION ISO.
*
Bulletin IIF - 177 Boulevard Malesherbes, Paris 17e - Volume XXXVIII, No 1.
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ISO/R 917-1968 (E)
CONTENTS
Page
Introduction .
5
1 . Scope . 5
2 . Definitions . 5
PART 1 . DETERMINATION OF REFRIGERATING CAPACITY
3 . General procedure . 6
4 . Basic test conditions and variations . 8
5 . Basis of calculations . 8
Test report . 8
6 .
Methods of test .
7 . 10
Method A : Secondary fluid calorimeter .
8 .
12 4
9 . Method B : Flooded system refrigerant calorimeter .
13
1 O . Method C : Dry system refrigerant calorimeter .
16
11 . Method D : Refrigerant vapour flow-meter .
18
12 . Method E : Refrigerant liquid quantity . 20
13 . Method F : Refrigerant liquid quantity and flow-meters .
23
14 . Method G : Water-cooled condenser method .
24
15 . Method H : Refrigerant vapour cooling method . 27
16 . Method J : Refrigerant vapour cooling method (alternative to Method H) .
30
17 . Method K : Calorimeter in compressor discharge line . 32
PART II . POWER PERFORMANCE
18 . Measurement of power absorbed .
36
ANNEXES
Annex A : Types and accuracy of measuring instruments . 37
Annex B : Symbols used in calculations .
39
Annex C : Method of error estimation .
42
FIGURES
Figures 1. 2 and 3 . Circuit diagrams for Methods A. B and C .
11
Figure 4 : Circuit diagrams for Method D .
19
Figures 5 and 6 . Circuit diagrams for Methods E and F .
21
Figure 7 : Circuit diagrams for Method G .
25
Figure 8 : Circuit diagram for Method H .
27
Figure 9 : Circuit diagram for Method J .
30
Figure 10 : Circuit diagrams for Method K .
33
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I
ISO/R 917-1968 (E
December 1968
R 917
IS0 Recommendation
TESTING OF REFRIGERANT COMPRESSORS
INTRODUCïION
This IS0 Recommendation applies only to refrigerant compressors considered as separate units, independently of
a complete refrigeration installation.
Selected methods of test are described for the determination of the refrigerating capacity and power perfor-
mance factor of a refrigerant compressor, with sufficient accuracy to permit consideration of its suitability to
operate satisfactorily under any set of basic test conditions required for a given refrigeration installation.
c
The methods for the determination of the refrigerating capacity are given in Part I.
The methods for the determination of the power performance factor are given in Part 11.
Attention is particularly drawn to a number of special precautions to be taken in order to reduce testing losses to
a minimum.
NOTE. - Tests on complete refrigeration installations are dealt with in IS0 Recommendation R 916, Testing of refrigerating
systems.
1. SCOPE
1.1 The provisions of this IS0 Recommendation apply only to single stage refrigerant compressors of the
positive volume displacement type. The methods of test described may however be used as a guide for the
testing of other types of refrigerant compressors.
1.2 This IS0 Recommendation applies only to tests carried out at the manufacturer’s works, or wherever the
necessary equipment for testing to the close limits required can be made available.
2. DEFINITIONS
A complete list of symbols and units used in calculation, together with their definitions, is given in Annex B.
2.1 Refngerating capacity of a refngerant compressor. Product of the mass flow rate of refrigerant through the
compressor, as derived from the test, and the difference between the specific enthalpy of the refrigerant in
its state at the measuring point at inlet of the compressor, and the specific enthalpy in the state of saturated
liquid at the temperature corresponding to the test discharge pressure at the measuring point at outlet of
the compressor.
2.2
Refngerating performance factor. Ratio of refrigerating capacity to power supplied.
NOTE. - It should be made clear whether the power referred to is measured at the compressor shaft, or is power
supplied at the motor terminals.
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ISO/R 917-1968 (E
PART I
DETERMINATION OF REFRIGERATING CAPACITY
3. GENERAL PROCEDURE
3.1 Determination of refrigerating capacity
The determination of the refrigerating capacity of a compressor comprises
the evaluation of the mass flow rate of the refrigerant, obtained for each method used by means of
(a)
the apparatus inserted in the outer part of the test circuit, between the inlet and the outlet of the
compressor, as described in sections 8 to 18;
the determination of the specific enthalpy of the refrigerant in the state of saturated liquid at the
(b)
compressor discharge pressure, and its specific enthaipy at the compressor suction pressure and
temperature, obtained by means of tables or diagrams of the characteristics of the refrigerant.
During the test, the refrigerant compressor should be provided with ail auxiliary equipment and accessories
necessary for its satisfactory operation in normal use.
3.2 Tests
The tests comprise a PRINCIPAL test and a CONFIRMING test which should be carried out simultaneously.
3.2.1 The CONFIRMING test should, wherever possible, be of a different type from the PRINCIPAL test, so
that its results are obtained independently from those of the PRINCIPAL test.
3.2.2 The value of the estimated error for the refrigerating capacity, as calculated for the PRINCIPAL test,
should be lower than that calculated from the selected CONFIRMING test (see Annex C).
3.2.3 Recommended methods for both types of tests and for possible combinations are given in section 7.
3.2.4 The results of the PRINCIPAL test are accepted provided that those of the CONFIRMING test are in
agreement to within * 4 O/'.
3.3 Generalrules
in order to ensure that the results obtained are within the required limits of accuracy, it is essential to
observe the following rules and to take into account the instructions given in the Note under clause 3.3.4.
3.3.1 Ali instruments and auxiliary measuring apparatus should have been correctly located in relation to the
compressor inlet and outlet, and should have been calibrated against master instruments of certified
accuracy and adjusted if necessary to give readings within the limits of accuracy prescribed in Annex A.
3.3.2 Pressure and temperature at suction inlet to the compressor should both be measured at the same point
and as nearly as possible eight pipe diameters of a straight run of pipeline, or 300 mm (1 2 in), whichever
is greater, ahead of the point of entry or of the stop valve, if one is fitted.
3.3.3 Pressure and temperature at the discharge outlet of the compressor should both be measured at the same
point and not less than eight pipe diameters of a straight run of pipeline, or 300 mm (12 in), whichever
is greater, after the point of outlet or the stop valve, if one is fitted.
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ISO/R 917-1968 (E)
3.3.4 The correct refrigerant and lubricating oil charges should be in the circulation system. Efficient oil
separators should be fitted in the discharge line of the compressor, and arrangements made to return
separated oil direct to the compressor lubricating system.
If the compressor is designed for use on a normal oil returning circuit, the oil from the separator should
be returned to the suction line between the measuring apparatus and the compressor suction connection.
No refrigerant should be added during the test, and no oil should be added to enclosed crank cases which
communicate with the refrigerant circuit.
During the whole of the test run, the circuit should contain only the refrigerant and the lubricating oil
in such conditions of purity that normal operation in the continuous running of the compressor will be
assured, and that the precision of the test measurements will not be affected within the agreed
tolerances.
NOTE. - The complete elimination of liquid refrigerant and lubricating oil would be difficult to achieve. However, the
error arising from these factors at inlet of the compressor can generally be reduced to such an extent as to be negligible
by
(a) ensuring that the refrigerant vapour is sufficiently superheated at inlet to the compressor. For this purpose a
suction superheater may be required, and any heat supplied to it from an external source should be duly
recorded;
(b) providing an efficient oil separator on the discharge line of the compressor.
In general, a correction for the effect of lubricating oil is not necessary if the oil content of the oil/liquid refrigerant
mixture, determined in the manner described in clause 12.3.3, is such as to cause an error not exceeding 1 y0 of the
refrigerating capacity.
3.3.5 The system should be tested for tightness, and all non-condensable gases should be eliminated.
3.3.6 The compressor should be protected against abnormal air currents.
3.4 Test period
3.4.1 The tests envisaged refer exclusively to refrigerant compressors operating continuously under conditions
such that, for a specified period, fluctuations in all the factors likely to affect the results of a test remain
between the limits prescribed, and show no definite tendency to move outside these limits.
These conditions are termed steady working conditions.
3.4.2 After the compressor has been started, adjustments should be made during a preliminaty run until the
essential measurements required for the test are within the allowable limits of variation.
3.4.3 The steady working conditions having been reached, the readings for the test period are taken at equal
time intervals not exceeding 20 minutes, for a period of at least 1 hour during which at least four
readings are taken and plotted as a curve.
Only minor adjustments are permitted during this period.
The use of recording instruments of accuracy compatible with the accuracy of the method used is
recommended.
3.4.4 The arithmetic mean of the successive readings for each measurement is taken as the value of the measure
ment for the test.
3.4.5 Quantity measurements should be made at the beginning and end of each interval to check uniformity of
operation, the difference between the first and last measurement of the test period being taken as the
value for the test.
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ISO/R 917-1968 (E)
4. BASIC TEST CONDITIONS AND VARIATIONS
The basic test conditions to be specified for the testing of a refrigerant compressor are as follows :
4.1 The absolute pressure at the measuring points in the suction and discharge pipeline of the compressor.
throughout the test period.
The pressure readings should not vary by more than ? 1
The suction temperature at the measuring point in the suction pipeline of the compressor. The temperature
4.2
readings should not vary by more than f 3 OC (i 5 OF) throughout the test period.
4.3 The speed of rotation of the compressor. The speed selected for the test should not differ by more than
f 1 O from the basic speed.
or
of the name-
The voltage at the motor terminals and the frequency. The voltage should be within f 2
plate value and the frequency within i 2 %.
5. BASIS OF CALCULATIONS
5. Specific enthaipy
Subject to the rules and precautions defined under clause 3.3, the specific enthalpy of the refrigerant
liquid at compressor discharge pressure, and the specific enthalpy at compressor suction pressure and
temperature, are obtained from recognized tables and diagrams of the thermodynamic properties of the
refrigerant used. A correction for the presence of entrained lubricating oil may be necessary in the second
case (see clause 12.3.3).
5.2 Mass flow rate of refrigerant
The mass flow rate is determined by a PRINCIPAL method selected from those described under sections
8 to 17, and confirmed by a suitable CONFIRMING test, the tests being carried out simultaneously (see
section 7).
5.3 Specific volume of the refrigerant
The actual test value vga of the specific volume of the refrigerant vapour at compressor inlet should not
differ by more than 2 from the value v corresponding to the specified basic test conditions.
gl
5.4 Value of the measured mass flow rate
Subject to the condition in clause 5.3, the value of the measured mass flow rate should be adjusted by
multiplying it by the factor vga /vg .
6. TEST REPORT
6.1 Genehi information
6.1.1 Date . Time started .
Time ended .
Duration .
6.1.2 Make and serial number of compressor.
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ISO/R 917-1968 (E)
6.1.3 Type of compressor (single or double acting, number of cylinders, etc.).
6.1.4 Cylinder diameter and stroke (if applicable).
6.1.5 Compressor displacement per revolution.
6.1.6 Designation of refrigerant.
6.2 Basic test conditions to be specified (see section 4)
6.2.1 Absolute pressure at compressor suction.
6.2.2 Temperature at compressor suction.
6.2.3 Absolute pressure at compressor discharge.
6.2.4 Rotational speed of compressor or electric supply details.
6.3 Methods of test used
6.3.1 PRINCIPAL test.
6.3.2 CONFIRMING test.
6.4 Average values of test readings (see section 3)
6.4.1 Rotational speed of compressor.
6.4.2 Ambient temperature.
6.4.3 Barometer reading.
6.4.4 Pressure of refrigerant at compressor suction inlet.
6.4.5 Temperature of refrigerant at compressor suction inlet.
6.4.6 Pressure of refrigerant at compressor discharge outlet.
6.4.7 Temperature of refrigerant at compressor discharge outlet.
6.4.8
Inlet temperature of cooling water.
6.4.9
Outlet temperature of cooling water.
6.4.10 Mass flow rate of cooling water.
6.4.1 1 When possible, compressor lubricating oil temperature.
6.4.12 Voltage and frequency of electrical supply.
NOTE. - Additional test information will be required depending on the methods of test used (see sections 8 to 18).
6.5 Test results
6.5.1 Heat leakage factors.
6.5.2 Mass flow rate of refrigerant.
6.5.3 Relevant enthalpy difference.
6.5.4 Refrigerating capacity of compressor.
6.5.5 Estimated error of results (see Annex C).
6.5.6 Remarks.
NOTE. - If the test is to include the measurement of power performance, the readings required in accordance with Part II
should be taken simultaneously with those of Part I.
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ISO/R 917-1968 (E)
7. METHODS OF TEST
Method A (see section 8) : Secondary fluid calorimeter in suction line.
7.1
(see section 9) : Flooded system refrigerant calorimeter in sucrion line.
Method B
Method C (see section 10) : Dry system refrigerant calorimeter in suction line.
A heat-insulated calorimeter is installed near the suction inlet of the compressor to act as the evaporator,
and the refrigerating effect is produced by the direct transfer of heat to the refrigerant from a suitable
controlled source.
NOTE. - Methods A, B and C should, wherever possible, be used as PRlNCIPAL METHODS.
7.2 Method G (see section 14) : Water-cooled condenser method.
The water-cooled condenser in the actual installation is suitably insulated and equipped to act as a
calorimeter.
7.3 Method K (see section 17) : Calorimeter in discharge line.
A heat-insulated calorimeter is installed in the discharge pipeline of the compressor to receive the total flow
of refrigerant in the gaseous state.
7.4 Method D (see section 1 I) : Refrigerant vapour flow-meter.
A flow-meter of the calibrated orifice or nozzle type is placed in either the compressor suction or the
compressor discharge line.
7.5 Method E (see section 12) : Refrigerant liquid quantity meter.
(see section 13) : Refrigerant liquid flow rate meter.
Method F
Method H (see section 15) : Refrigerant vapour cooling.
Method 1 (see section 16) : Alternative to Method H.
Methods E and F measure the total flow of the refrigerant in the liquid state.
Methods H and J measure the flow of B portion only of the liquid refrigerant obtained fromaspecial
condenser.
Methods G, K, D, E, F, H and J should in general be used as CONFIRMING METHODS. However, in cases
where it is not practicable to employ Methods A, B and C as PRINCIPAL METHODS, it is permissible to
make use of Methods D, G and K for this purpose provided the total mass flow passes through the measuring
apparatus, and the special precautions referred to under clause 3.3 are strictly observed.
7.6 Possible combinations
The following combinations of PRlNCIPAL METHODS and CONFIRMING METHODS are possible,
taking into account the conditions set out under clause 3.2.
1
PRINCIPAL METHOD POSSIBLE CONFIRMING METHOD
Method A
Method B
Method C
Method D
Method G
Method K
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ISO/R 917-1968 (E)
FIG. 1 - Method A
Heater
FIG. 2 ~ Method B
FIG. 3 - Method C
Circuit diagrams for Methods A, B and C
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ISO/R 917-1968 (E
8. METHOD A : SECONDARY FLUID CALORIMETER (see Fig. 1)
8. I Description
The secondary fluid calorimeter consists of a direct expansion coil or set of coils in parallel serving as a
primary evaporator. This evaporator is suspended in the upper part of a pressure-tight heat-insulated vessel.
A heater is located in the base of this vessel, which is charged with a volatile secondary fluid so that the
heater is well below the liquid surface. The refrigerant flow is controlled by either a hand regulator or a
constant pressure expansion valve, which should be located close to the calorimeter. The expansion valve
and the refrigerant pipelines connecting it to the calorimeter may be insulated in order to minimize the gain
of heat.
The calorimeter is insulated in such a manner that the heat leakage does not exceed 5 of the capacity of
the compressor.
Provision should be made for measuring the pressure of the secondary fluid with an accuracy of
+ 0.05 kgf/cm2(I 0.7 lbf/in2) and for ensuring that this pressure does not exceed the safety limit for the
apparat us.
8.2 Calibration
The calorimeter should be calibrated by the following heat loss method :
8.2.1 The heat input to the secondary fluid is adjusted so as to maintain the pressure constant at a value
corresponding to a temperature of saturation approximately 14 "C (25 OF) above the ambient air
temperature. The ambient air temperature is maintained constant to within * 1 "C (I 2 OF) at any
desired value not exceeding 43 "C (I 10 OF).
8.2.2 If the heater is operated continuously, the heat input is maintained constant to within 2 1 and the
pressure of the secondary fluid is measured at hourly intervals until four successive values of the corres-
ponding temperature of saturation do not vary by more than ? 0.6 "C (+ 1 OF).
8.2.3 If the heater is operated intermittently, the control should be such that the temperature of saturation
corresponding to the secondary fluid pressure is maintained constant to within + 0.6 "C (+ 1 OF) of
the desired value and readings of heat input are taken at hourly intervals until four successive readings
+. 4 "Io.
do not vary by more than
8.2.4 The heat leakage factor can then be calculated from the following formula :
8.3 Test procedure
The suction pressure is adjusted by means of the refrigerant control, and the temperature of the refrigerant
vapour entering the compressor is adjusted by varying the heat input to the secondary fluid. The discharge
pressure is adjusted by varying the temperature and flow of the condensing medium, or by a pressure
control device in the discharge he.
8.3.1 If the heater is operated continuously, the fluctuation in heat input due to any cause during the test
period should not be such as to cause a variation of more than 1
in the calculated compressor
capacity.
8.3.2 If the heater is operated intermittently, the temperature of saturation corresponding to the secondary
fluid pressure should not vary by more than k 0.6 "C (I 1 OF).
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ISO/R 917-1968 (E
8.4 Additional information
The following information should be recorded :
8.4.1 Pressure of refrigerant vapour at evaporator outlet.
8.4.2 Temperature of refrigerant vapour at evaporator outlet.
8.4.3 Pressure of refrigerant liquid entering expansion valve.
8.4.4 Temperature of refrigerant liquid entering expansion valve.
8.4.5 Ambient temperature at calorimeter.
8.4.6 Pressure of secondary fluid.
8.4.7 Heat input to secondary fluid.
8.5 Determination of refrigerating capacity
8.5.1 The mass flow rate of the refrigerant, as determined by the test, is given by the following formula :
8.5.2 The refrigerating capacity, adjusted to the specified basic test conditions, is given by the following
formula :
a,, = m, (he - h, )- 'ea
' I vel
9. METHOD B : FLOODED SYSTEM REFRIGERANT CALORIMETER (see Fig. 2)
9.1 Description
The flooded system refrigerant calorimeter consists of a pressure-tight evaporator vessel, or vessels in
parallel, in which heat is applied direct to the refrigerant in respect of which the compressor is being tested.
The refrigerant flow is controlled by a hand regulator, a constant pressure expansion valve, or a suitable level
control device, which should be located close to the calorimeter. The expansion valve and the refrigerant
pipeline connecting it to the calorimeter may be insulated in order to minimize the gain of heat.
The calorimeter should be insulated in such a manner that the heat leakage does not exceed 5
of the
capacity of the compressor.
Provision should be made for ensuring that the refrigerant pressure does not exceed the safety limit for the
apparatus.
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ISO/R 917-1968 (E)
9.2 Calibration
The calorimeter should be calibrated by one of the following methods :
9.2,1 Heat loss method. The heat loss method of calibration is carried out by means of the following
procedure :
The calorimeter is filled with refrigerant liquid to its normal operating level and the liquid and
9.2.1.1
vapour outlet stop valves closed. The ambient temperature is maintained constant to within
t 1 "C (t 2 OF) at any desired value not exceeding 43 "C (1 10 OF) and heat is supplied to
maintain the refrigerant temperature approximately 14 "C (25 OF) above the ambient tempera-
ture. Where liquid is used for heating, the inlet temperature is maintained constant to within
I 0.3 OC (t 0.5 OF) and the flow controlled so that the temperature drop is not less than
6 "C (10 OF). Where electric heating is used, the input is maintained constant to within f 1
9.2.1.2
After thermal equilibrium has been established, readings are taken for the following periods :
- for liquid heating, at hourly intervals until four successive readings of both inlet and ouelet
temperatures, with constant rate flow, do not vary by more than 0.3 "C (t 0.5 F);
- for electric heating, at hourly intervals until four successive values of the temperature of
saturation of the refrigerant do not vary by more than f 0.6 "C (t 1 OF).
9.2.1.3
The heat input to the calorimeter is determined as follows :
for liquid heating
- for electric heating
Qi = P W = 0.86 P kcal/h = 3.41 P Btu/h
9.2.1.4 The heat leakage factor can then be calculated from the following formula :
9.2.2 Condensing unit method. The condensing unit method of calibration is carried out by means of the
following procedure :
The ambient temperature of the calorimeter is maintained constant to within f 1 "C (t 2 OF) at
any desired value not exceeding 43 "C (1 10 OF). A condensing unit of appropriate capacity is operated on
the calorimeter until steady conditions are reached with a temperature difference between the ambient
temperature and the temperature of saturation of the refrigerant of 27 2 1 "C (40 * 2 OF). The
condensate is collected and measured in volume measuring vessels by the procedure described in
Method E (see section 12) over such a period of time as to ensure that the height of the liquid accumu-
lated in the measuring vessel is at least 150 mm (6 in). The test is continued until four successive
readings taken at hourly intervals do not vary by more than I5 O/".
The heat leakage factor can then be calculated from the following formula
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ISO/R 917-1968(E
9.3 Test procedure
The suction pressure at the compressor is adjusted by means of the refrigerant control, and the inlet
temperature to the compressor is adjusted by varying the heat input, except when a level control is used, in
which case the suction pressure is adjusted by means of the heat input to the evaporator, and'the inlet
temperature to the compressor by the heat input to a superheater. The discharge pressure is controlled by
varying the temperature and flow of the condensing medium, or by a pressure control device in the dis-
charge line.
9.3.1 Where liquid is used for heating, the inlet temperature should be maintained constantoto within
I 0.3 "C (? 0.5 OF) and the flow controlled so that the temperature fall is not less than 6 C (10 OF).
The mass of liquid circulated should be maintained constant to within f 0.5 O/". Where electric heating
is used, the input should be maintained constant to within f 1 O/".
9.3.2 The variation in heat input during the test should not be sufficient to cause an error of more than 1 "k
in compressor capacity.
9.4 Additional information
The following information should be recorded :
9.4.1 Pressure of refrigerant vapour at evaporator outlet.
9.4.2 Temperature of refrigerant vapour at evaporator outlet.
9.4.3 Pressure of refrigerant liquid entering expansion valve.
9.4.4 Temperature of refrigerant liquid entering expansion valve.
9.4.5 Ambient temperature at calorimeter.
9.4.6 Temperature of heating liquid entering calorimeter.
9.4.7 Temperature of heating liquid leaving calorimeter.
9.4.8 Mass flow rate of heating liquid circulated.
9.4.9 Electrical input to calorimeter.
9.5 Determination of refrigerating capacity
9.5.1 The mass flow rate of the refrigerant, as determined by the test, is given by the following formula :
- for liquid heating :
- for electric heating :
9.5.2 The refrigerating capacity, adjusted to the specified basic test conditions, is given by the following
formula :
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ISO/R 917-1968 (E)
10. METHOD C : DRY SYSTEM REFRIGERANT CALORIMETER (see Fig. 3)
10.1 Description
The dry system refrigerant calorimeter consists of an arrangement of refrigerant tubes or tubular vessels of
suitable length and diameter to accomplish evaporation of the refrigerant circulated by the compressor. The
external surface of the evaporator may be heated, either by means of a liquid circulating in an outer
jacket, which may be a concentric tube, or electrically. Alternatively, similar means of heating may be used
within the evaporator.
The refrigerant flow is controlled by either a hand regulator or a constant pressure expansion valve, which
should be located close to thecalorimeter. The expansion valve and the refrigerant pipeline connecting it to
the calorimeter may be insula
...