Compressors and condensing units for refrigeration - Performance testing and test methods - Part 2: Condensing units

This European Standard applies only to condensing units for refrigeration and describes a number of selected performance test methods. These methods provide sufficiently accurate results for the determination of the refrigerating capacity, power absorbed, refrigerant mass flow and the coefficient of performance.
This European Standard applies only to performance tests conducted at the manufacturer's works or wherever the instrumentation and load stability for testing to the accuracy required is available.

Kältemittel-Verdichter und Verflüssigungssätze für die Kälteanwendung - Leistungsprüfung und Prüfverfahren - Teil 2: Verflüssigungssätze

Compresseurs et unités de condensation pour la réfrigération - Essais de performance et méthodes d'essais - Partie 2 : Unités de condensation

La présente Norme européenne s’applique uniquement aux unités de condensation pour la réfrigération et décrit une sélection de méthodes d’essai des performances. Ces méthodes fournissent des résultats d’une exactitude suffisante pour déterminer la puissance frigorifique, la puissance absorbée, le débit masse du fluide frigorigène et le coefficient de performance.
La présente Norme européenne s’applique uniquement aux essais de performance conduits dans les usines des fabricants ou en des endroits où l’on dispose de l’instrumentation et d’une stabilité de charge permettant d’effectuer les essais avec l’exactitude requise.

Kompresorji in kondenzacijske enote za hladilne naprave - Preskušanje lastnosti in preskusne metode - 2. del: Kondenzacijske enote

Ta evropski standard se uporablja samo za kondenzatorske enote za hlajenje in opisuje izbrane metode za preskušanje zmogljivosti. Te metode zagotavljajo dovolj natančne rezultate za določanje zmogljivosti hlajenja, porabe energije, pretoka hladilne tekočine in koeficienta zmogljivosti.
Ta evropski standard se uporablja le pri preskušanju lastnosti v tovarni proizvajalca ali povsod, kjer so na voljo instrumenti in stabilnost bremena za preskušanje pri zahtevani natančnosti.

General Information

Status
Published
Public Enquiry End Date
31-Dec-2016
Publication Date
12-Feb-2018
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
12-Jan-2018
Due Date
19-Mar-2018
Completion Date
13-Feb-2018

RELATIONS

Buy Standard

Standard
SIST EN 13771-2:2018
English language
30 pages
sale 10% off
Preview
sale 10% off
Preview

e-Library read for
1 day

Standards Content (sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Kompresorji in kondenzacijske enote za hladilne naprave - Preskušanje lastnosti in preskusne metode - 2. del: Kondenzacijske enoteKältemittel-Verdichter und Verflüssigungssätze für die Kälteanwendung - Leistungsprüfung und Prüfverfahren - Teil 2: VerflüssigungssätzeCompresseurs et unités de condensation pour la réfrigération - Essais de performance et méthodes d'essais - Partie 2 : Unités de condensationCompressors and condensing units for refrigeration - Performance testing and test methods - Part 2: Condensing units27.200Hladilna tehnologijaRefrigerating technology23.140VWURMLCompressors and pneumatic machinesICS:Ta slovenski standard je istoveten z:EN 13771-2:2017SIST EN 13771-2:2018en,fr,de01-marec-2018SIST EN 13771-2:2018SLOVENSKI

STANDARDSIST EN 13771-2:20081DGRPHãþD
SIST EN 13771-2:2018
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 13771-2
September
t r s y ICS
t uä s v râ
t yä t r r Supersedes EN
s u y y sæ tã t r r yEnglish Version

Compressors and condensing units for refrigeration æ Performance testing and test methods æ Part

tã Condensing units Compresseurs et unités de condensation pour la réfrigération æ Essais de performance et méthodes d 5essais æ Partie

t ã Unités de condensation

KältemittelæVerdichter und Verflüssigungssätze für die Kälteanwendung æ Leistungsprüfung und Prüfverfahren æ Teil

tã Verflüssigungssätze This European Standard was approved by CEN on
t x July
t r s yä

egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä

translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä

CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Serbiaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä

EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels

t r s y CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN

s u y y sæ tã t r s y ESIST EN 13771-2:2018
EN 13771-2:2017 (E) 2 Contents Page

European foreword ....................................................................................................................................................... 3 1 Scope .................................................................................................................................................................... 4 2 Normative references .................................................................................................................................... 4 3 Terms, definitions and symbols ................................................................................................................. 4 3.1 Terms and definitions ................................................................................................................................... 4 3.2 Symbols ............................................................................................................................................................... 7 3.3 Refrigerant circuit state points ............................................................................................................... 10 4 Uncertainty of measurement and test conditions ............................................................................ 10 4.1 Uncertainty of performance data ........................................................................................................... 10 4.2 Uncertainty of measurement ................................................................................................................... 10 4.3 Test conditions .............................................................................................................................................. 12 5 General requirements ................................................................................................................................ 13 5.1 Test equipment ............................................................................................................................................. 13 5.2 Calculation methods .................................................................................................................................... 13 5.3 Requirements for the selection of test methods ............................................................................... 15 5.4 Test procedure .............................................................................................................................................. 15 5.5 Pressure and temperature measuring points.................................................................................... 15 5.6 Oil circulation ................................................................................................................................................ 16 5.7 Refrigerant composition............................................................................................................................ 16 5.8 Calibration and requirements regarding measurement uncertainty ....................................... 16 5.9 Source of refrigerant data ......................................................................................................................... 17 5.10 Test setup for air cooled condensing units ......................................................................................... 17 6 Test methods ................................................................................................................................................. 18 6.1 General ............................................................................................................................................................. 18 6.2 List of test methods ..................................................................................................................................... 18 6.3 Method A: secondary fluid calorimeter on the suction side ......................................................... 19 6.4 Method B: dry system refrigerant calorimeter on the suction side ........................................... 20 6.5 Method C: Water cooled condenser calorimeter .............................................................................. 22 6.6 Method D: Refrigerant gas flow meter on the suction side (see 6.6) ......................................... 23 6.7 Method E: refrigerant flow meter in the liquid line ......................................................................... 24 7 Determination of the power absorbed by the condensing unit .................................................. 26 7.1 General ............................................................................................................................................................. 26 7.2 Calculation ...................................................................................................................................................... 26 8 Test report ...................................................................................................................................................... 27 8.1 General ............................................................................................................................................................. 27 8.2 Test data .......................................................................................................................................................... 28 8.3 Test results ..................................................................................................................................................... 28 8.4 Overview of test values .............................................................................................................................. 28 Bibliography ................................................................................................................................................................. 30

SIST EN 13771-2:2018

EN 13771-2:2017 (E) 3 European foreword This document (EN 13771-2:2017) has been prepared by Technical Committee CEN/TC 113 “Heat pumps and air conditioning units”, the secretariat of which is held by UNE. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2018, and conflicting national standards shall be withdrawn at the latest by March 2018. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 13771-2:2007. The following significant changes compared to the previous edition have been incorporated in this European Standard: a) alignment of symbols and indexes with EN 13771-1; b) introduction of a new Figure 1 “Condensing unit configurations” and revision of the Figures 2 to 7; c) introduction of the new Clause 4 “Uncertainty of measurement and test conditions”; d) specification of a detailed test room and setup description to reduce testing uncertainty, aligned with EN 327 and EN 14511-3; e) adoption to transcritical operation and cyclic capacity control. EN 13771 consists of the following parts, under general title Compressors and condensing units for refrigeration — Performance testing and test methods: — Part 1: Refrigerant compressors — Part 2: Condensing units According to the CEN-CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 13771-2:2018

EN 13771-2:2017 (E) 4 1 Scope This European Standard applies only to condensing units for refrigeration and describes a number of selected performance test methods. These methods provide sufficiently accurate results for the determination of the refrigerating capacity, power absorbed, refrigerant mass flow and the coefficient of performance. This European Standard applies only to performance tests conducted at the manufacturer's works or wherever the instrumentation and load stability for testing to the accuracy required is available. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 378-1, Refrigerating systems and heat pumps - Safety and environmental requirements - Part 1: Basic requirements, definitions, classification and selection criteria EN 378-2, Refrigerating systems and heat pumps - Safety and environmental requirements - Part 2: Design, construction, testing, marking and documentation ISO 817, Refrigerants — Designation and safety classification 3 Terms, definitions and symbols 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1.1 refrigerating capacity Q Ãcondensing unitÄ product of the refrigerant mass flow and the difference between the specific enthalpy of the refrigerant at the inlet of the condensing unit (Figure 1, point 11) and the specific enthalpy of the fluid at the outlet of the condensing unit (Figure 1, point 12) Note 1 to entry: The outlet (point 12) of condensing unit depends on design (single stage or two stage or internal heat exchangers, see Figure 1 a), b), c) and d).

SIST EN 13771-2:2018
EN 13771-2:2017 (E) 5
subcritical transcritical
a) Single stage condensing units
subcritical transcritical
b) Two stage / open flash / condensing units
subcritical transcritical
c) Condensing units with economizer
subcritical transcritical

d) Condensing unit with internal HX Key 1 refrigerant gas at the compressor inlet 11 refrigerant gas at the condensing unit inlet 2 refrigerant gas at the compressor outlet 12 refrigerant liquid/fluid at the condensing unit outlet 5 refrigerant liquid/fluid at the expansion device inlet

Figure 1 — Condensing unit configurations SIST EN 13771-2:2018

EN 13771-2:2017 (E) 6 3.1.2 specific enthalpy 3.1.2.1 specific enthalpy of the refrigerant at the inlet of the condensing unit specific enthalpy of the refrigerant at pressure and temperature to the inlet (superheated above the dew point temperature to the stated value) 3.1.2.2 specific enthalpy of the refrigerant fluid at the outlet of the condensing unit specific enthalpy of the refrigerant at pressure and temperature at the outlet 3.1.3 subcooling

¿T12 difference between the bubble point temperature of the refrigerant corresponding to the pressure at the condensing unit outlet and the temperature of the liquid refrigerant measured at the same place Note 1 to entry: Applicable for subcritical pressure only. 3.1.4 power absorbed P power demand to drive the condensing unit 3.1.5 refrigerant mass flow m refrigerant mass flow at the condensing unit inlet 3.1.6 coefficient of performance COPR ratio of the refrigerating capacity to the power absorbed Note 1 to entry: Both the above are at the specified test condition. 3.1.7 subcritical operation operating condition with condensing unit outlet pressure below the critical pressure of the refrigerant 3.1.8 transcritical operation operating condition with condensing unit outlet pressure above the critical pressure of the refrigerant 3.1.9 part load operation operation with active capacity control at reduced capacity for compressors with capacity control mechanism Note 1 to entry: On/off cycling of the compressor motor is not considered as capacity control. SIST EN 13771-2:2018

EN 13771-2:2017 (E) 7 3.1.10 fluid refrigerant liquid, gas or vapour including the state of appearance close to and above the critical pressure 3.1.11 oil circulation ratio xoil ratio of the measured oil mass flow to the mass flow of the circulating oil/refrigerant mixture 3.1.12 condensing unit combination of one or more compressors, condensers/gas coolers and, where applicable, liquid receivers and the regularly furnished accessories Note 1 to entry: In transcritical operation the condenser operates as gas cooler. 3.1.13 cyclic capacity control control that reduces suction flow in cycles shorter than the test period, without switching off compressor motors 3.2 Symbols For the purposes of this document, the symbols in Table 1 and the indices in Table 2 apply. SIST EN 13771-2:2018

EN 13771-2:2017 (E) 8 Table 1 — Symbols Symbol Designation SI unit c specific heat capacity J/(kg K) coil specific heat capacity of oil J/(kg K) COPR coefficient of performance

f electrical frequency Hz F heat leakage factor W/K h specific enthalpy J/kg n compressor speed 1/min P power absorbed W Pm actual compressor power absorbed where the motor is not an integral part of the unit W Pel actual compressor power absorbed where the motor is an integral part of the unit W Pf power absorbed by the fans and other regularly furnished auxiliaries W Ph electrical power input to the heater W p absolute pressure MPa m mass flow kg/s V volume flow m3/s

¿T12 subcooling K t temperature °C tcal mean surface temperature of the calorimeter °C ts1 inlet temperature of heating or cooling liquid °C ts2 outlet temperature of heating or cooling liquid °C tmid mean of the bubble and dew point temperature of the refrigerant at the condensing unit outlet pressure °C tbs bubble temperature of the secondary fluid °C tx reference temperature °C U nominal electrical voltage V v specific volume of refrigerant gas m3/kg

density of the refrigerant gas/fluid; indexed for other fluids kg/m3 Qi heat flow to the calorimeter W Q refrigerating capacity W xoil oil circulation ratio — SIST EN 13771-2:2018

EN 13771-2:2017 (E) 9 Table 2 — Indices Index Designation
1 refrigerant gas at the compressor inlet
2 refrigerant gas at the compressor outlet
3 condenser inlet
4 condenser outlet
5 inlet expansion device
6 evaporator (or calorimeter) outlet
11 condensing unit inlet
12 condensing unit outlet
a actual
A air
amb ambient
cal calorimeter surface
f heat transfer fluid
in inlet
M flow meter
oil oil
out outlet
s secondary fluid (secondary refrigerant, brine or water)
x oil/liquid refrigerant mixture
F fans and other auxiliary components
SIST EN 13771-2:2018

EN 13771-2:2017 (E) 10 3.3 Refrigerant circuit state points Figure 2b) shows the state of the refrigerant in the refrigerating circuit shown in Figure 2a).

a) Circuit diagram b) Pressure vs enthalpy diagram Key 1 refrigerant gas at the compressor inlet A compressor 2 refrigerant gas at the compressor outlet B condenser (including any receiver and/or sub-cooler 3 refrigerant gas at the condenser inlet

forming an integral part of the unit) 4 refrigerant liquid at the condenser outlet C expansion device 5 refrigerant liquid at the expansion device inlet D evaporator 6 refrigerant gas at the evaporator outlet

11 refrigerant gas at the condensing unit inlet
12 refrigerant liquid at the condensing unit outlet

Figure 2 — Refrigerant circuit 4 Uncertainty of measurement and test conditions 4.1 Uncertainty of performance data Measuring instruments shall be selected and calibrated so that the final result is within the maximum uncertainties of the measured value as indicated: — refrigerating capacity: ± 2,5 %, — electrical power absorbed: ± 1 % and — mechanical power absorbed: ± 2,5 %. 4.2 Uncertainty of measurement Uncertainty values are considered to cover a 95 % confidence interval, i.e. ± 2 times the standard deviation. Except where otherwise stated in the particular clauses, measurements shall be carried out within the maximum uncertainty of the measured value as given in Table 3. SIST EN 13771-2:2018

EN 13771-2:2017 (E) 11 Table 3 — Uncertainties of measurement for indicated values Measured quantity Unit Uncertainty of measurement Absolute pressure Pa ±1 % Electrical

— current A ±1 % — frequency s «1 ±1 % — power (except for fans and auxiliaries) W ±1 % — power of fans and auxiliaries W ±3 % — voltage V ±1 % Refrigerant flow kg/s ±1 % Rotational speed min «1 ±0,07 % Mass kg ±0,2 % Temperatures

— temperature for differences (for individually calibrated sensors) °C ±0,05 K — temperature differences (for calibrated sensor pairs) K ±1 % — other temperatures °C ±0,3 K Time interval s ±0,1 % Torque Nm ±1 % Water flow kg/s ±1 % Length, width or height m ±2 % Adherence to the limits listed in this table does not ensure the requirements of 4.1 are obtained automatically. SIST EN 13771-2:2018

EN 13771-2:2017 (E) 12 4.3 Test conditions The specified test conditions under which the test is to be performed and their allowable deviations are given in Table 4. Table 4 — Specified test conditions and the allowable deviations Specified test conditions Allowable deviation during the entire test period Absolute pressure a, condensing unit inlet, p11 ±1,0 % Absolute pressure a, condensing unit outlet water cooled, p12 ±1,0 % Refrigerant temperature at the condensing unit inlet, t11 ±3,0 K Refrigerant subcooling at the condensing unit outletá

¿T12 0 K to +1 K Nominal compressor speed, n ±1,0 % Nominal electrical voltage, U ±1,5 % Nominal electrical frequency, f ±1,0 % Air inlet temperature at condenser/gas cooler, tA ±1,0 K Liquid temperature at condenser, ts1 ±0,5 K Liquid temperature at condenser b, ts2 ±0,5 K Liquid flow rate through the condenser, ms ±1,5 % Ambient temperature c, tamb ±3,0 K a Dynamic deviations due to pulsations are not considered. b May be used as an alternative to liquid flow rate. c Other than air inlet temperatures. The values for the relevant specified test conditions shall be recorded. For the calculation of refrigeration capacity - additional values might be needed: — gas cooler outlet temperature in case of transcritical operation. For cyclic capacity control the deviations of Table 4 refer to the average values per control cycle. For operation with constant capacity, the deviations can be applied either — to every single recorded value, or — to the average values per minute, or — to the average of the values for the test period, ± 2 times standard deviation of the measured values. The air inlet temperature tA is the average instantaneous value of all temperature sensors. SIST EN 13771-2:2018

EN 13771-2:2017 (E) 13 5 General requirements 5.1 Test equipment All equipment shall comply with the requirements of EN 378-2. 5.2 Calculation methods 5.2.1 Principle The determination of the refrigerating capacity of a condensing unit at the specified test conditions comprises: — evaluation of the actual mass flow of refrigerant at the condensing unit inlet (m11)when operating within the limits allowed to the specified test conditions in Table 4; — correction of this mass flow to the value at the specified test conditions using the ratio of the actual specific volume (v11a) of the refrigerant gas at the condensing unit inlet to the specific volume of the gas at the specified test conditions (v11); — product of the corrected mass flow and the difference between the specific enthalpies at the specified test conditions of the refrigerant gas at the condensing unit inlet (h11), and the liquid refrigerant at the condensing unit outlet (h12). NOTE For the purpose of this standard it is assumed that the volume flow rate is constant when the condensing unit is operating within the limits allowed in Table 4. 5.2.2 Specific enthalpy The value of the specific enthalpy is listed in the recognized data of the thermodynamic properties of the refrigerant used depending on pressure and temperature. 5.2.3 Refrigerant mass flow The refrigerant mass flow is either measured directly or calculated from measured values. 5.2.4 Power absorbed Within a superheat range of ± 3 K it is assumed that the power consumption will stay constant. 5.2.5 Basic formulae The refrigerant mass flow m determined by measurement is converted to that at the specified test conditions using the following formula: For condensing units without compressor motors =×11aa11avnmmvn (1) For condensing units with compressor motors 11aa11avfmmvf=×=(2)=SIST EN 13771-2:2018

EN 13771-2:2017 (E) 14 The refrigerating capacity as defined in 3.1.1 for condensing units is calculated using the following formula: ()1112Qmhh=×−=(3)=The=power=absorbed=by=the=condensing=×nit=as=defined=in=3.1.4=is=converted=from=the=meas×red=power=absorbed=to=that=at=the=specified=test=conditions=×sing=the=following=form×la:=aFanPPPn=×+=(4)=where=P is the power absorbed by the condensing unit at specified test conditions; Pa for motor compressors: Pel; Pa for externally driven compressors: Pm; PF is the power absorbed by the fan and/or other auxiliary components. The conversion for condensing units without compressor motors is given by the following formula: FmanPPPn=+×=(5)=where=P is the power absorbed by the condensing unit at specified test conditions; PF is the power absorbed by the fan and/or other auxiliary components; Pm is the power absorbed by the compressor(s) at actual test conditions; n is the compressor speed. The conversion for condensing units with compressor motors is given by the following formula: FelafPPPf=+×=(6)=where=P is the power absorbed by the condensing unit at specified test conditions; PF is the power absorbed by the fan and/or other auxiliary components; Pel is the power absorbed by the compressor(s) at actual test conditions; f is the supply frequency of the power to the compressor motor. NOTE It is not necessary to correct PF because this change is insignificant in comparison to P. SIST EN 13771-2:2018

EN 13771-2:2017 (E) 15 The coefficient of performance COPR as defined in 3.1.6 is calculated using the following formula: RQCOPP==(7)=5.3 Requirements for the selection of test methods 5.3.1 General In general two different test methods as specified in Clause 6 shall be used at the same time for determining the mass flow. The results of the two methods shall not differ more than 4 %. The test result is the mean value of the two methods. Different methods according to 6.2 are allowed to be combined for the determination. 5.3.2 Second concurrent test Where testing devices are in constant use and are subject to periodical calibration in accordance with the recommended EN ISO 9001 a second concurrent test is not necessary. 5.4 Test procedure 5.4.1 General The tests specified refer exclusively to a condensing unit operating continuously under conditions so that, for a specified period, fluctuations in all the factors likely to affect the results of a test remain within the limits prescribed and show no definite tendency to move outside these limits. These conditions are specified as steady working conditions and are defined precisely in 4.3. 5.4.2 Steady working conditions After the condensing unit has been started, adjustments shall be made during a preliminary run until the measurements required are within the allowable deviations regarding Table 4. Depending on the chosen test method, additional parameters are relevant for test results (see Table 5). These parameters have to be stable to an extent which is considered not to increase the uncertainty of the result significantly. A linear trend up or down of more than 50 % of the allowable deviations during the test period might indicate non steady-state conditions. Compressor mechanical equilibrium (run-in time) has to be considered according the manufacturer's requirements. 5.4.3 Recording of measured data Once steady working conditions have been reached, the measured data shall be recorded. At least one complete measuring cycle shall be carried out every minute. The recording period shall be at least 15 min. The mean value of any measured quantity shall be calculated from all the values of this quantity during the recording period. When using cyclic capacity control at least 15 complete measuring readings have to be taken per control cycle. The test period shall comprise only complete control cycles and at least 10. Averages shall additionally be formed from all measured values per cycle. 5.5 Pressure and temperature measuring points The pressure and temperature at the inlet of the condensing unit shall be measured at the same place. This shall be located in a straight run of pipe at a distance of at least four times the pipe diameter, but not less than 150 mm from the shut-off valve or connection. SIST EN 13771-2:2018

EN 13771-2:2017 (E) 16 The diameter of the pipe shall be consistent with that of the connection on the condensing units for a length of at least eight times the pipe diameter. The pressure and temperature at the outlet of the condensing unit shall be measured in a similar manner. 5.6 Oil circulation The quantity of oil in circulation shall be determined after the test. From the liquid phase of the refrigerant circuit the refrigerant/oil mixture shall be poured into a collecting device intended for this specific purpose and the oil fraction determined. In case of repeated tests of a compressor type for the known quantity of oil in circulation, random sampling may be sufficient. Alternative procedures with the same accuracy may be used. The collecting device shall be constructed according to EN 378-2. 5.7 Refrigerant composition The composition of any refrigerant to be used in a test shall be in accordance with ISO 817. NOTE Zeotropic refrigerants have a certain composition in the as-specified condition. Changes in pressure and temperature can cause a change in the concentration of the different components in the circulating refrigerant. This can be exacerbated by unfavourable distribution of the refrigerant in the circuit, leakage from the system and selective oil solubility. The thermodynamic properties will also change with resulting inaccuracies in the determination of performance data. 5.8 Calibration and requirements regarding measurement uncertainty 5.8.1 Calibration of calorimeters for methods A, B and C Calorimeters for methods A, B and C shall be calibrated by determining a heat leakage factor ()ixambQFtt=−=(8)=which=specifies=the=heat=exchange=between=the=calorimeter=and=the=ambient=temperat×re.=The=reference=temperat×re=tx depends on the calorimeter type and determines the heat exchange to the ambient temperature. It can be: a) the bubble temperature tbs of the secondary fluid (e.g. method A, single component refrigerant is recommended); b) mean surface temperature tcal of the calorimeter (e.g. method B); c) mean of refrigerant bubble and dew point temperatures tmid corresponding to the calorimeter outlet pressure (e.g. method C). The following method shall be used to determine the heat leakage factor. Before starting the test maintain the ambient temperature tamb at a constant and supply a heat flow Qi to maintain the reference temperature

...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.