1、_6$(7HFKQLFDO6WDQGDUGV%RDUG5XOHVSURYLGHWKDW7KLVUHSRUWLVSX EOLVKHGE6$(WRDGYDQFHWKHVWDWHRIWHFKQLFDO and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, LVWKHVROHUHVSRQ
2、VLELOLWRIWKHXVHUSAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2017 SAE InternationalAll rights reserved. No part of this publication may be reproduced, sto
3、red in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada)Tel: +1 724-776-4970 (outside USA)Fax: 724-776-0790Ema
4、il: CustomerServicesae.orgSAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on thisTechnical Report, please visithttp:/standards.sae.org/J2762_201703SURFACE VEHICLESTANDARDJ2762MAR2017Issued 2011-02Reaffirmed 2017-03Superseding J2762 FEB2011Method for Removal of Refrigeran
5、t from Mobile Air Conditioning System toQuantify Charge AmountRATIONALEJ2762 has been reaffirmed to comply with the SAE Five-Year Review policy.1. SCOPE This Standard provides an overview of results and requirements needed to remove refrigerant from a mobile air conditioning system for determining r
6、efrigerant emissions (leakage). This reclaim procedure for use on fleet vehicles in a field service environment should produce an accuracy and repeatability sufficient to determine refrigerant loss within 2 g. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this spec
7、ification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA),
8、 www.sae.org.SAE J2788 HFC-134a (R-134a) Recovery/Recycle/Recharging Equipment and for Mobile Air-Conditioning Systems SAE J2791 HFC-134a Refrigerant Electronic Leak Detectors, Minimum Performance Criteria 2.1.2 Other Publications I-MAC Report Team 1-Refrigerant Leakage Reduction, Final Report to Sp
9、onsors, Eugene Dianetti, Aug., 2007 Research study on the definition of the implementation of a method of measurement of annual leak flow rates (LFRs) of MAC systems, Dennis Clodic, -Ecoles Des Mines, Jan., 2006 3. BACKGROUND 3.1 The Effect of System Design on the Refrigerant Recovery Process 3.1.1
10、When refrigerant is removed from the system, the lowering of pressure results in some of the system components becoming cooler. This component cooling effect makes complete refrigerant removal in a short period of time more difficult. To remove as much of the refrigerant as possible during the recov
11、ery process, systems equipped with orifice tubes and accumulators require more time than systems equipped with expansion valves/receiver driers. This is mainly because of the design differences between accumulators and receiver driers (being larger than receiver driers, accumulators, located in the
12、low pressure side of the system where the refrigerant is cold and more refrigerant can be held by the oil, hold more refrigerant and oil than do receiver driers). 3.2 The amount of refrigerant recovered from a system depends on how much is in the system, and the temperature of the work area. When th
13、e refrigerant is recovered, the vacuum lowers the temperature of the various components in the system; the oil chills and forms a virtual barrier to reduce refrigerant evaporation. 3.3 I-MAC CRP Results 3.3.1 Refrigerant Recovery Standard for System Charge Level Determination Final Assessment 3.3.1.
14、1 The procedure was tested on selected vehicles with a variety of A/C system configurations (CCOT, TXV, Dual systems). Different types of oil-less recovery pumps were investigated in an attempt to reduce variation of refrigerant recovery quantities. 3.3.1.2 The use of dry ice or liquid nitrogen was
15、rejected as a viable option for field-testing due to availability and safety concerns. Refrigerant recovery quantities achieved by following the published procedure did not produce the desired accuracy and repeatability for all A/C system types. All testing was conducted at room temperature. Consist
16、ent evacuation levels and times were maintained. 3.3.1.3 Recovery variation is largely dependent on the refrigerant vaporization rate and the amount of refrigerant remaining in solution with the oil within the a/c system at evacuation terminus. It is believed that the amount of refrigerant recovered
17、, and the associated repeatability, would be improved significantly by elevating the vehicle temperature to 30 C during reclaim. This was also rejected as being impractical in a field environment. 3.3.1.4 It is difficult and unreliable to remove refrigerant from mobile A/C systems and quantify syste
18、m emissions. 3.3.1.4.1 Tests performed for the SAE I-MAC research program indicates that the surrounding temperature greatly affects the recovery process. Equipment used is shown in Figure 1. _SAE INTERNATIONAL J2762 MAR2017 Page 2 of 9FIGURE 1 - RECOVERY VACUUM PUMP AND CYLINDER USED IN LABORATORY
19、REFRIGERANT RECOVERY PROCEDURE 3.3.1.4.2 If the system is opened, the remaining refrigerant will be vented to the atmosphere. 3.3.1.4.3 If the system recharges to specification, it will overcharge. 3.3.1.4.4 The development of SAE J2788 (December 2006 replacing SAE J2210) recovery/recharging equipme
20、nt has improved refrigerant recovery capability during service. However, the equipment is not capable of recovering the entire amount refrigerant in a system. 3.3.1.5 Recovery at 21 C with SAE J2210 recovery equipment left over 18% of the refrigerant in the system. At a work area ambient of 10 C nea
21、rly 30% of the refrigerant remained in the system. FIGURE 2 - RECOVERED REFRIGERANT WHEN USING SAE J2210 RECOVER/RECYCLE EQUIPMENT AT 10 C AND 21 C WORK AREA TEMPERATURE _SAE INTERNATIONAL J2762 MAR2017 Page 3 of 93.4 Ecoles Des Mines Study Results For each type of vehicle, in order to demonstrate t
22、hat the refrigerant is recovered with a precision of less than 1 g, the refrigerant has been recovered just after the initial charge and after a half an hour of running the A/C system. 3.4.1 Background The procedure as followed by the trained and experienced operators is presented in Annex 1. Prior
23、to the ACEA fleet test the CEP laboratory had a long experience in recovery and was well aware of the number of difficulties associated with high precision for recovery and charge. So a procedure has been first written. Recovery equipment using an oil free compressor has been modified in order not t
24、o trap any refrigerant. A training period has been set where step by step all actions have been studied in order not to lose any refrigerant when connecting and disconnecting hoses, to limit oil recovery with the refrigerant and to control all surroundings conditions: garage temperature, engine comp
25、artment temperature, A/C system temperature. 3.4.2 Equipment Special recovery equipment: oil free and without any tank or heat exchanger. Scale with a weighing precision of 0.1 g, special (low weight) recovery cylinder dedicated to each vehicle, recovery hoses dedicated to each vehicle, temperature
26、and pressure sensors to control the operating conditions. 3.4.3 First Recovery The recovery system is connected to the low pressure service valve of the A/C system. The recovery mass flow rate is controlled by a throttling valve at the suction port of the recovery equipment in order to keep it slow
27、and only in gas phase to avoid oil recovery with the liquid phase of the refrigerant. The 1st recovery operation ends when the final pressure is of 20 kPa abs. The recovery system (recovery equipment + recovery hoses + recovery cylinder) are weighed and the recovered refrigerant known by the differe
28、nce between the evacuated recovery system and the recovery system with the 1st recovered refrigerant. 3.4.4 Second Recovery The engine compartment is heated in order the A/C system temperature to reach 40 C during 30 min minimum. This operation is done in order to evaporate liquid refrigerant either
29、 trapped in the compressor, or in the oil, or in any part of theA/C system. From all vehicles it is noticed that the pressure inside the A/C system raises from 20 kPa up to 50 to 70 kPa. The second recovery is carried out identically to the 1st one down to 15 to 17 kPa abs. The recovery system is we
30、ighed. If the recovered refrigerant mass is superior to 1g (which is always the case) a third recovery is performed. 3.4.5 Third Recovery Recovery is carried out with the same steps as described above and the 3rd recovery is the final one if the recovered refrigerant mass is lower than 1 g. 3.4.6 Re
31、covery for Assessment of the Accuracy The same steps are performed, as described for the initial recovery. Moreover verification of possible oil recovery is carried out. The recovery cylinder is heated to 40 C and the refrigerant in gas phase is slowly recovered from the recovery cylinder. Then the
32、remaining refrigerant is evacuated with a vacuum pump. Then the evacuated cylinder is weighed as done initially; if oil has been recovered with the refrigerant, its mass is the difference between the initial weighing and the last one. When all those steps are carried out, the method is considered as
33、 validated if the recovered mass of refrigerant is the same as the charged one at 1 g difference. _SAE INTERNATIONAL J2762 MAR2017 Page 4 of 9In summary, the recovery process is performed as follows: an oil free compressor is used; the car engine compartment is heated up to 40 C minimum; the recover
34、y is performed after running the A/C system during 30 min; the recovery mass flow rate is very slow (about 4 to 7 g/min) in order to limit or to avoid any oil recovery; the recovery process is performed down to 15 to 17 kPa abs pressure, and several recoveries are necessary until less than 1 g of re
35、frigerant is recovered; the recovered R-134a is then separated from possible oil in order to avoid misleading results due to oil recovery. 3.5 Procedure for Refrigerant Extraction All refrigerant charge and recovery operations have to be performed according to the following procedures: 3.5.1 Record
36、the room temperature when performing the operations measured at 20 cm in front of the car. 3.5.2 Record the following pressures: 1. the residual pressure of the system before the refrigerant charge, 2. the pressure of the MAC system after the refrigerant recovery, 3. the pressure of the recovery equ
37、ipment before the refrigerant recovery, 4. the effective refrigerant charge, with the error calculation, 5. the recovered refrigerant mass, with the error calculation, 6. the mass of oil recovered from the refrigerant, with the error calculation. 3.5.3 Equipment 3.5.3.1 Scales, accuracy 0.1 g 3.5.3.
38、2 Recovery equipment, oil-less without any container or heat exchanger, capable to lower the pressure of the MAC system down to 0.2 bar abs (20 kPa abs). The recovery equipment has a pressure sensor at the suction port capable to measure the pressure with an accuracy of 0.05% of the measurement scal
39、e from 0 to 100 kPa. 3.5.3.3 Recovery cylinder (empty weight smaller than 3 kg). The recovery cylinder has a high pressure sensor in order to verify the saturating pressure once the temperature equilibrium is reached after recovery (in order to verify the absence of non condensable gases). 3.5.3.4 D
40、istillation cylinder used to transfer refrigerant from the recovery cylinder in order to weigh the oil content trapped in the recovery cylinder. 3.5.3.5 Leak detector with a sensitivity of 4 g/year according to SAE J2791 standard. 3.5.3.6 Heat generator in order to heat up the volume around the car
41、at a minimum temperature of 20 C and to heat up the engine compartment at a temperature in the range of 40 C. _SAE INTERNATIONAL J2762 MAR2017 Page 5 of 93.5.3.7 Soft electrical resistance to heat the recovery cylinder. 3.5.3.8 Two temperature sensors: one connected directly to the suction line in o
42、rder to verify possible liquid trapping, and the other connected to the compressor to check the temperature. 3.5.4 Initial Recovery 3.5.4.1 Preparation of the Recovery Conditions 3.5.4.1.1 The garage ambient temperature around the car is raised up to 20 C minimum using the heat generator. 3.5.4.1.2
43、The car is run during 20 min in order to heat up the engine compartment. 3.5.4.1.3 The A/C system is run in a forced mode if the A/C is automated control. The evaporator blower velocity is on position 3, and the A/C system is run at least 15 min in order to heat up the compressor and to permit first
44、 out-gassing of the refrigerant out of the oil. 3.5.4.1.4 The A/C system and the engine are turned off.3.5.4.1.5 The hood is opened and possible leaks are searched using the leak detector, first on the compressor, and then on all the visible fittings. 3.5.4.2 Preparation of the Recovery System 3.5.4
45、.2.1 The recovery cylinder is evacuated with a vacuum pump down to 20 Pa abs. 3.5.4.2.2 The recovery cylinder is weighed without any connections. 3.5.4.2.3 All the recovery system, i.e., the recovery cylinder, the hoses, and the recovery equipment, is evacuated with a vacuum pump down to 20 Pa abs.
46、3.5.4.2.4 The recovery equipment plus the connecting hoses plus the recovery cylinder (empty) are weighed all together.3.5.4.3 Recovery Process 3.5.4.3.1 First Recovery 3.5.4.3.1.1 The recovery process begins after the leak search by connecting the hoses to the low and high pressure service valves w
47、hen available. 3.5.4.3.1.2 The throttling valve at the suction port of the recovery equipment is progressively opened so that the oil flush does not occur. This is confirmed by observing the sight glass attached downstream of the throttling valve. 3.5.4.3.1.3 When the pressure in the A/C system starts lowering, the throttling valve is progressively opened in order to keep the mass flow rate in the same range of 20 g/min. 3.5.4.3.1.4 Durin
