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1、 AS 1731.122003 Australian Standard Refrigerated display cabinets Part 12: Measurement of the heat extraction rate of the cabinets when the condensing unit is remote from the cabinet AS 1731.12 This Australian Standard was prepared by Committee ME-008, Refrigerated Display Cabinets. It was approved
2、on behalf of the Council of Standards Australia on 26 September 2003 and published on 1 October 2003. The following are represented on Committee ME-008: Australian Greenhouse Office Australian Retailers Association Commercial Refrigeration Manufacturers Association of Australia Food Science Australi
3、a Institution of Engineers Australia Refrigeration Air Conditioning Companies Association Keeping Standards up-to-date Standards are living documents which reflect progress in science, technology and systems. To maintain their currency, all Standards are periodically reviewed, and new editions are p
4、ublished. Between editions, amendments may be issued. Standards may also be withdrawn. It is important that readers assure themselves they are using a current Standard, which should include any amendments which may have been published since the Standard was purchased. Detailed information about Stan
5、dards can be found by visiting the Standards Australia web site at .au and looking up the relevant Standard in the on-line catalogue. Alternatively, the printed Catalogue provides information current at 1 January each year, and the monthly magazine, The Global Standard, has a full listing of revisio
6、ns and amendments published each month. We also welcome suggestions for improvement in our Standards, and especially encourage readers to notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at .au, or write to the Chief Executive, Standards Australia International
7、 Ltd, GPO Box 5420, Sydney, NSW 2001. This Standard was issued in draft form for comment as DR 03217. The Standard is downloaded from Standard Sharing AS 1731.122003 Australian Standard Refrigerated display cabinets Part 12: Measurement of the heat extraction rate of the cabinets when the condensin
8、g unit is remote from the cabinet Originated as AS B2201966. Previous edition AS 1731.122000. Second edition 2003. COPYRIGHT Standards Australia International All rights are reserved. No part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including ph
9、otocopying, without the written permission of the publisher. Published by Standards Australia International Ltd GPO Box 5420, Sydney, NSW 2001, Australia ISBN 0 7337 5536 4 AS 1731.122003 2 PREFACE This Standard was prepared by the Australian members of the Joint Standards Australia/Standard New Zea
10、land Committee ME-008, Refrigerated Display Cabinets, to supersede AS 1731.122000, Refrigerated display cabinets, Part 12: Measurement of the heat extraction rate of cabinets when the condensing unit is remote from the cabinet. After consultation with stakeholders in both countries, Standards Austra
11、lia and Standards New Zealand decided to develop this Standard as an Australian, rather than an Australian/New Zealand Standard. This Standard is based on International Standard prEN ISO 23953-2:2003, Refrigerated display cabinets, Part 2: Classification, requirements and test conditions. This Stand
12、ard is Part 12 of a series of Standards for refrigerated display cabinets, as follows: AS 1731 Refrigerated display cabinets 1731.1 Part 1: Terms and definitions 1731.2 Part 2: General mechanical and physical requirements 1731.3 Part 3: Linear dimensions, areas and volumes 1731.4 Part 4: General tes
13、t conditions 1731.5 Part 5: Temperature test 1731.6 Part 6: Classification according to temperatures 1731.7 Part 7: Defrosting test 1731.8 Part 8: Water vapour condensation test 1731.9 Part 9: Electrical energy consumption test 1731.10 Part 10: Test for absence of odour and taste 1731.11 Part 11: In
14、stallation, maintenance and user guide 1731.12 Part 12: Measurement of the heat extraction rate of the cabinets when the condensing unit is remote from the cabinet (this Standard) 1731.13 Part 13: Test report 1731.14 Part 14: Minimum energy performance standard (MEPS) requirements The Standard is do
15、wnloaded from Standard Sharing 3 AS 1731.122003 CONTENTS Page 1 SCOPE4 2 REFERENCED DOCUMENTS4 3 OBJECTIVE .4 4 TEST PROCEDURE.4 5 DETERMINATION OF HEAT EXTRACTION RATE6 6 METHOD .11 7 TEST REPORT.17 AS 1731.122003 4 Standards Australia .au STANDARDS AUSTRALIA Australian Standard Refrigerated displ
16、ay cabinets Part 12: Measurement of the heat extraction rate of the cabinets when the condensing unit is remote from the cabinet 1 SCOPE 1.1 Scope of Standard This Standard specifies terminology, general mechanical and physical requirements, test conditions as well as installation and maintenance, i
17、ncluding a users guide, for refrigerated display cabinets for the sale or display, or both, of food products. This Standard does not cover refrigerated vending machines, cabinets intended for use in catering and similar non-retail applications or food service cabinets. 1.2 Scope of Part 12 This Part
18、 of AS 1731 specifies heat extraction rate measurements and conditions for refrigerated display cabinets when the condensing unit is remote from the cabinet and used with compression-type or indirect-type refrigerating system. 2 REFERENCED DOCUMENTS The following documents are referred to in this St
19、andard: AS 1731 Refrigerated display cabinets 1731.4 Part 4: General test conditions 1731.5 Part 5: Temperature test 1731.13 Part 13: Test report AS/NZS 1677 Refrigerating systems 1677.1 Part 1: Refrigerant classification 3 OBJECTIVE The objective of this Standard is to establish a procedure for the
20、 measurement of the heat extraction rate of remote and indirect refrigerating systems for use by manufacturers, suppliers, purchasers, operators and regulators of these systems. 4 TEST PROCEDURE 4.1 General test conditions The cabinet shall be installed in the test room and the test shall be prepare
21、d and carried out during the temperature test, in accordance with AS 1731.4 and AS 1731.5. The condensing unit shall be connected to the cabinet in accordance with Clauses 4.2 or 4.3 and the operating controls set to the manufacturers instructions. The Standard is downloaded from Standard Sharing 5
22、 AS 1731.122003 .au Standards Australia The refrigerant inlet and outlet temperatures shall be measured using temperature sensors. The sensors shall be directly inserted into the pipe or pockets, or clamped between the piping and a copper recovery half-sleeve on the inlet and outlet pipelines positi
23、oned no further than 150 mm from the cabinet exterior (see Figures 1 and 3). Where thermocouples or similar devices are utilized, the sensor cables shall be arranged such that external influences on the connection cables are eliminated by the use of insulation. Temperature sensors, connecting wires
24、and pipelines shall be insulated from the outlet of the cabinet up to at least 150 mm beyond the measuring points. A flow measuring device (flow meter) shall be installed in the liquid inlet supply line to the cabinet, in order to measure the liquid mass flow or volume flow rate of refrigerant. A li
25、quid sight glass shall be installed in the liquid piping upstream of the flow meter, in order to verify the vapour-free state of the refrigerant being supplied to the cabinet during the period of the test. A temperature sensor shall be installed as stated above at 150 10 mm upstream of the liquid fl
26、ow meter, with the piping being insulated at least 150 mm upstream and from the sensor to the inlet of the flow meter. A measurement of pressure shall be carried out at the cabinet outlet for compression type systems, and both inlet and outlet for indirect type systems, at less than 150 mm from the
27、cabinet. The heat extraction rate necessary for the cabinet shall be determined from the temperature, pressure and flow rate readings that allow a resultant accuracy of 5%. 4.2 Specific test conditions for cabinets intended for connection to compression-type refrigerating system The condensing unit
28、remotely located from the cabinet shall be connected to the cabinet in accordance with Figure 1. Details of reference point locations are shown in Figure 2. The condensing unit selected for the test shall be capable of operating as follows: (a) With the refrigerant at the saturated evaporating press
29、ure or temperature in service at the cabinet outlet specified by the manufacturer. (b) Supplying the liquid refrigerant vapour free at the cabinet inlet (see the two sight glasses in Figure 1) at a sensible temperature within the range of +25C to +45C, or supplying sub-cooled liquid when specified.
30、In both conditions, the liquid temperature shall be stated. NOTES: 1 Minimum condensing temperatures in the region of +30C to +35C are encountered with water-cooled condensers. 2 The heat extraction rate of the compressor can be adjusted by having the condensing temperature increased, which may brin
31、g the liquid temperature to +45C. 3 An oil separator may be installed at the discharge of compressor to minimize the oil content of the refrigerant. 4.3 Specific test conditions for cabinets intended for connection to indirect-type refrigerating system The indirect-type refrigerating system shall be
32、 connected to the cabinet intended for this system in accordance with Figure 3. The refrigerating system shall be capable of supplying secondary refrigerant fluid at the temperature and flow rate specified by the manufacturer. AS 1731.122003 6 Standards Australia .au 5 DETERMINATION OF HEAT EXTRACTI
33、ON RATE 5.1 Cabinets intended for compression-type refrigerating system For each individual measuring instant, the heat extraction rate in kW is defined as: () 48mn hhq= . . . 4.1 where n = the heat extraction rate required (kW) h8, h4 = the specific enthalpy (kJ/kg), where the state at point 8 corr
34、esponds to the refrigerant outlet of the cabinet and the state at point 4 corresponds to the refrigerant inlet of the cabinet qm = the mass flow rate of liquid refrigerant (kg/s), if a mass flow meter is used; or = qv3/v3 where qv3 = the volume flow rate (m3/s) v3 = the specific volume of liquid ref
35、rigerant (m3/kg), at the flowmeter inlet temperature 3 if a volumetric flowmeter is used NOTES: 1 As pressures, temperatures and liquid volume flow rates change in the course of the operating cycle (for instance, pull down after defrost), the values to be taken into consideration are the arithmetic
36、mean values of the values recorded or values of each measurement which are recorded in accordance with a given frequency, during 75% of the operating time, excluding defrost and the time just after defrost 2 Where cycling takes place during the test period, the above procedure may be used. The flow
37、temperatures and pressures will be the arithmetic mean values leading to a mean value of qm considering both the period of running and the period of stopping of the compressor. Readings should be taken with a frequency of 20 to 60 s. The percentage cycling time of the system during the test period a
38、nd the minimum evaporating temperature should be published in addition to the mean heat extraction rate, to enable equipment selection ratings to be calculated. The Standard is downloaded from Standard Sharing 7 AS 1731.122003 .au Standards Australia FIGURE 1 CONNECTION OF THE CABINET TO A REMOTE C
39、OMPRESSION-TYPE REFRIGERATING SYSTEM AS 1731.122003 8 Standards Australia .au FIGURE 2A REFERENCE POINT LOCATIONS FOR A CABINET CONNECTED TO A REMOTE COMPRESSION-TYPE REFRIGERATION SYSTEM FIGURE 2B PRESSURE ENTHALPY DIAGRAM SHOWING MEASURING POINTS 5.2 Cabinets intended for indirect-type refrigerati
40、ng system The heat extraction rate shall be determined from the following equation (see Figures 3 and 4): () iom0 =cq . . . 5.1 where 0 = the heat extraction rate required in kilowatts (kilojoules per second) i = the secondary refrigerant temperature at cabinet inlet in degrees Celsius o = the secon
41、dary refrigerant temperature at cabinet outlet in degrees Celsius c = the specific heat (kJ/kg.K) qm = the mass flow rate (kg/s), if a mass flowmeter is used; or = qv The Standard is downloaded from Standard Sharing 9 AS 1731.122003 .au Standards Australia where qv= is the volume flow rate (m3/s) =
42、 the secondary refrigerant density (kg/m3) at the flow-metre inlet temperature i if a volumetric flowmetre is used NOTE: Where cycling takes place during the test period, the above procedure may be used. The flow temperatures and pressure will be the arithmetic mean values leading to a mean value of
43、 qm considering both the period of running and the period of stopping of the secondary refrigerant flow. Readings should be taken with a frequency of 20 to 60 s. The percentage cycling time of the system during the test period should be published in addition to the mean heat extraction rate, to enab
44、le equipment selection ratings to be calculated. AS 1731.122003 10 Standards Australia .au FIGURE 3 CONNECTION OF A CABINET TO A REMOTE INDIRECT-TYPE REFRIGERATING SYSTEM FIGURE 4 REFERENCE POINT LOCATIONS FOR A CABINET CONNECTED TO A REMOTE INDIRECT-TYPE REFRIGERATING SYSTEM The Standard is downloa
45、ded from Standard Sharing 11 AS 1731.122003 .au Standards Australia 6 METHOD 6.1 General The summation of n over 24 h gives: (a) the total heat extraction Qtot in kWh: (see Figures 4 to 6 ). = = = max 1 ntot . Nn n tQ . . . 6.1 (b) the steady state heat extraction Q75 in kWh during 75% of the refri
46、gerating time period excluding the period just after defrost (see Figure 4 ). = = = = = di i Nn n Q 11 n75 75 . . . 6.2 The heat extraction rate for compression and indirect-type refrigerating systems shall be reported in the following ways: run which represents the heat extraction rate necessary fo
47、r a single cabinet installation, in laboratory conditions, (kW) run75 which represents the steady state heat extraction rate necessary for a single cabinet installation during 75% of the refrigerating period excluding the time just after defrost, in laboratory conditions, (kW) for continuous running
48、 only 24 which represents the heat extraction rate necessary for a multi cabinet installation, in laboratory conditions, (kW) 24-deft which represents a heat extraction rate for calculating the energy consumption of a cabinet, in laboratory conditions, (kW) 6.2 Determination of heat extraction rates (see Figures 5 to 7 ) The heat extraction rates are determined as follows: run can be calculated by arithmetic averaging of the instant heat extraction rates n during the running time only (trun) stopdeft tot run tot run h24tt Q t Q = . . . 6.3