The method of performance test for positive displacement refrigerant compressors
1 Scope
This standard is applicable to single-stage refrigerant compressors of the positive-displacement type. Selected test methods are described for the determination of the refrigerating capacity, the power, the volume efficiency, the isentropic efficiency and the coefficient of performance (refrigerating effect per unit power) of such compressors.
The test methods described may also be used as a guide for the testing of other types of refrigerant compressors.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections) to, or revisions, of any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the referenced document applies.
GB/T 2624 Measurement of fluid flow by means of orifice plates, nozzles and Venturi tubes inserted in circular cross-section conduits running full (eqv ISO 5176-1:1991)
GB 9237 Mechanical refrigerating systems used for cooling and heating - Safety requirements (eqv ISO 5149:1993)
3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
refrigerant compressor capacity, Φ0
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 vapour at the inlet of the compressor and the specific enthalpy of the liquid at the saturated temperature (or dew point temperature) corresponding to the discharge pressure at the outlet of the compressor
3.2
volume efficiency, ηv
ratio of the actual volume flow rate under compressor suction conditions, measured at the specified position, to the theoretical displacement of the compressor
3.3
input power, P
power at the compressor shaft for an open compressor or power at the motor terminals for a hermetic motor compressor (or semi-hermetic motor compressor) together with the power absorbed by such ancillaries as are necessary to sustain the operation of the compressor, e.g. oil pump
3.4
isentropic efficiency, η1
ratio of the product of the actual mass flow rate of refrigerant and the change in isentropic enthalpy across the compressor to the power input of the compressor
3.5
coefficient of performance, ε
ratio of the refrigerating capacity to the power input of the compressor
4 Test requirements
4.1 General requirements
4.1.1 Non-condensable gases shall be purged from the test system. The test system shall be tested for freedom from leaks of refrigerant.
4.1.2 A sufficient amount of refrigerant that complies with the relevant standards shall be present in the system. The compressor shall maintain the amount of lubricating oil necessary for normal operation.
4.1.3 Efficient oil separators shall be fitted in the discharge line to restrict the oil content in the circulating refrigerant liquid to no more than 1.5% by mass. Refer to Annex A for the measurement method.
4.1.4 The pressure and temperature at the suction inlet to or the discharge outlet of the compressor shall be measured at the same point which shall be located on a straight run of pipeline, at a distance of 0.3 m, beyond the suction line valve or discharge line valve, if one is fitted. For hermetic compressors without valves, the point shall be located on a straight run of pipeline, at a distance of 0.15 m from the compressor shell.
4.1.5 The test system shall be protected against abnormal air currents in its vicinity.
4.1.6 The ambient temperature of the test system shall be (30 ± 5)°C.
4.1.7 Equipment shall be provided for extracting samples of the refrigerant-oil mixture for oil content measurement.
4.2 Test requirements
4.2.1 All compressor performance test shall comprise two test methods, a test X and a test Y, which shall be carried out simultaneously.
4.2.2 The results of test X and test Y shall be accepted provided that they correlate within ±4%. The arithmetic mean of the successive readings for each measurement is taken as the value of the measurement for the test.
4.2.3 During compressor testing, the system shall achieve a thermal equilibrium state, and the test duration shall generally be no less than 1.5 hours. After half an hour since steady test conditions have been reached, the readings shall be taken and recorded at an interval of 20 min until the results from four consecutive measurements comply with the requirements specified in Table 2 of 4.3, and 4.2.2. The duration from the first to the fourth measurement record is defined as the test cycle, during which minor adjustments to pressure, temperature, flow rate, and liquid level are permitted.
4.2.4 Types of test methods
As specified in 4.2.1, all tests shall comprise two test methods. For each test, the information specified in the test report (see 4.5.2) together with the additional information specified for each test method shall be measured during the test period. Nine different test methods may be used as follows.
Method A: Secondary fluid calorimeter (see clause 5.1);
Method B: Flooded system refrigerant calorimeter (see 5.2);
Method C: Dry system refrigerant calorimeter (see 5.3);
Method D1: Refrigerant vapour flowmeter in the suction line (see 5.4);
Method D2: Refrigerant vapour flowmeter in the discharge line (see 5.4);
Method F: Refrigerant liquid flowmeter (see 5.5);
Method G: Water-cooled condenser calorimeter (see 5.6);
Method J: Refrigerant vapour cooling (see 5.7);
Method K: Calorimeter in compressor discharge line (see 5.8).
Contents
Foreword I
ISO foreword III
1 Scope
2 Normative references
3 Terms and definitions
4 Test requirements
5 Test methods
6 Input power calculation
7 Determination of the coefficient of performance
8 Determination of volume efficiency
9 Determination of isentropic efficiency
10 Deviation between tests with X and Y methods
Annex A (Informative) Measurement method for oil content
Annex B (Informative) Symbols used in formulae
The method of performance test for positive displacement refrigerant compressors
1 Scope
This standard is applicable to single-stage refrigerant compressors of the positive-displacement type. Selected test methods are described for the determination of the refrigerating capacity, the power, the volume efficiency, the isentropic efficiency and the coefficient of performance (refrigerating effect per unit power) of such compressors.
The test methods described may also be used as a guide for the testing of other types of refrigerant compressors.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections) to, or revisions, of any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the referenced document applies.
GB/T 2624 Measurement of fluid flow by means of orifice plates, nozzles and Venturi tubes inserted in circular cross-section conduits running full (eqv ISO 5176-1:1991)
GB 9237 Mechanical refrigerating systems used for cooling and heating - Safety requirements (eqv ISO 5149:1993)
3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
refrigerant compressor capacity, Φ0
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 vapour at the inlet of the compressor and the specific enthalpy of the liquid at the saturated temperature (or dew point temperature) corresponding to the discharge pressure at the outlet of the compressor
3.2
volume efficiency, ηv
ratio of the actual volume flow rate under compressor suction conditions, measured at the specified position, to the theoretical displacement of the compressor
3.3
input power, P
power at the compressor shaft for an open compressor or power at the motor terminals for a hermetic motor compressor (or semi-hermetic motor compressor) together with the power absorbed by such ancillaries as are necessary to sustain the operation of the compressor, e.g. oil pump
3.4
isentropic efficiency, η1
ratio of the product of the actual mass flow rate of refrigerant and the change in isentropic enthalpy across the compressor to the power input of the compressor
3.5
coefficient of performance, ε
ratio of the refrigerating capacity to the power input of the compressor
4 Test requirements
4.1 General requirements
4.1.1 Non-condensable gases shall be purged from the test system. The test system shall be tested for freedom from leaks of refrigerant.
4.1.2 A sufficient amount of refrigerant that complies with the relevant standards shall be present in the system. The compressor shall maintain the amount of lubricating oil necessary for normal operation.
4.1.3 Efficient oil separators shall be fitted in the discharge line to restrict the oil content in the circulating refrigerant liquid to no more than 1.5% by mass. Refer to Annex A for the measurement method.
4.1.4 The pressure and temperature at the suction inlet to or the discharge outlet of the compressor shall be measured at the same point which shall be located on a straight run of pipeline, at a distance of 0.3 m, beyond the suction line valve or discharge line valve, if one is fitted. For hermetic compressors without valves, the point shall be located on a straight run of pipeline, at a distance of 0.15 m from the compressor shell.
4.1.5 The test system shall be protected against abnormal air currents in its vicinity.
4.1.6 The ambient temperature of the test system shall be (30 ± 5)°C.
4.1.7 Equipment shall be provided for extracting samples of the refrigerant-oil mixture for oil content measurement.
4.2 Test requirements
4.2.1 All compressor performance test shall comprise two test methods, a test X and a test Y, which shall be carried out simultaneously.
4.2.2 The results of test X and test Y shall be accepted provided that they correlate within ±4%. The arithmetic mean of the successive readings for each measurement is taken as the value of the measurement for the test.
4.2.3 During compressor testing, the system shall achieve a thermal equilibrium state, and the test duration shall generally be no less than 1.5 hours. After half an hour since steady test conditions have been reached, the readings shall be taken and recorded at an interval of 20 min until the results from four consecutive measurements comply with the requirements specified in Table 2 of 4.3, and 4.2.2. The duration from the first to the fourth measurement record is defined as the test cycle, during which minor adjustments to pressure, temperature, flow rate, and liquid level are permitted.
4.2.4 Types of test methods
As specified in 4.2.1, all tests shall comprise two test methods. For each test, the information specified in the test report (see 4.5.2) together with the additional information specified for each test method shall be measured during the test period. Nine different test methods may be used as follows.
Method A: Secondary fluid calorimeter (see clause 5.1);
Method B: Flooded system refrigerant calorimeter (see 5.2);
Method C: Dry system refrigerant calorimeter (see 5.3);
Method D1: Refrigerant vapour flowmeter in the suction line (see 5.4);
Method D2: Refrigerant vapour flowmeter in the discharge line (see 5.4);
Method F: Refrigerant liquid flowmeter (see 5.5);
Method G: Water-cooled condenser calorimeter (see 5.6);
Method J: Refrigerant vapour cooling (see 5.7);
Method K: Calorimeter in compressor discharge line (see 5.8).
Contents of GB/T 5773-2004/XG1-2011
Contents
Foreword I
ISO foreword III
1 Scope
2 Normative references
3 Terms and definitions
4 Test requirements
5 Test methods
6 Input power calculation
7 Determination of the coefficient of performance
8 Determination of volume efficiency
9 Determination of isentropic efficiency
10 Deviation between tests with X and Y methods
Annex A (Informative) Measurement method for oil content
Annex B (Informative) Symbols used in formulae
