1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW16767 Air Conditioning Component Selection Procedure for Single or Dual Evaporator Systems Copyright 2012 General Motors Company All Rights Reserved August 2012 Originating Department: North American Engineering Standards Page 1 of 16 1 Scope Note:
2、Nothing in this standard supercedes applicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Purpose. The purpose of this analysis procedure is to provide an analytical method for determining the perfor
3、mance attributes of a Heating, Ventilation and Air Conditioning (HVAC) system. 1.2 Foreword. This test procedure should be used to evaluate an HVAC systems sensitivity to its Bill of Material (BOM) components as well as to vehicle specific attributes. Historically, air conditioning components were s
4、elected based on a steady state operation in fresh air mode. This was done to both minimize the assumptions required to perform the analysis and reduce the variation inherent to transient analysis. Similarly, this procedure uses steady state points to select components for the HVAC system for the sa
5、me reason. 1.3 Applicability. This procedure is applicable for both single evaporator and dual evaporator air conditioning systems used in passenger vehicles. A single evaporator and chiller system can also use this procedure by simply exchanging the rear evaporator for a chiller. Usage of an Intern
6、al Heat Exchanger (IHX) involves pressure drop and capacity balance, and is a tuning element beyond the scope of this sizing activity. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. None 2.2 GM Standards/Specifi
7、cations. GMW3032 GMW3058 GMW3202 GMW3037 GMW3067 GMW16151 2.3 Additional References. CG2924 e-Thermal System Simulation Program Environmental Protection Agency (EPA) Web site Manufacturer Web sites Vehicle Synthesis Analysis and Simulation (VSAS) Procedure; 30.05-XX Air Conditioning (A/C) System Siz
8、ing Simulation Guidelines 3 Resources 3.1 Facilities. Not applicable. 3.2 Equipment. 3.2.1 Access to e-Thermal Simulation Tool. 3.2.2 A Computer Capable of Running e-Thermal. 3.2.3 Matlab Version Compatible with the Version of e-Thermal that is running (Matlab for Unified Vehicle Model (UVM). 3.2.4
9、Sinda-Fluent Solver. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16767 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 2 of 16 3.3 Test Vehicle/Test Piece. Not applicable. 3.4 Test
10、Time. Calendar time: 3 to 4 days Test hours: 24 to 32 hours Coordination hours: Not applicable 3.5 Test Required Information. Figure 1: Process to Establish Vehicle Technical Specification (VTS) Targets 3.5.1 See Figure 1. A final, program specific VTS communicates customer requirements for system p
11、erformance. In the present example, the VTS of the Air Conditioning (A/C) system is to stipulate requirements to ensure 1) human thermal comfort and 2) battery thermal environment, satisfy the user. Human thermal comfort in a stratified, convective, and solar environment is simplified in terms of an
12、 Equivalent Homogenous Temperature (EHT). The tools to optimize a climate control system to EHT requirements are not yet broadly available; therefore, the thermal climate VTS requirements are denoted in terms of the temperature in the breath region, the A/C discharge temperature and the overall syst
13、em airflow (system capacity); with the intent to achieve a satisfactory EHT under a variety of operating conditions. Understand The Proposed Vehicles Thermal Needs Determine Proposed Vehicle Size Classification (see Appendix A, Table A1) Vehicle Powertrain (Conventional/Hybrid) 2nd/3rd Row Air Deliv
14、ery or Battery Cooling (Liquid/Air Cooled) Market Destination (United States, Europe, Asia, Middle East, etc.) Select GM Baseline Select a GM Vehicle Based on Vehicle Size (see Appendix A, Table A1) Choose a Powertrain Similar to Proposed Vehicle - i.e., engine displacement, number of cylinders, ERE
15、V, PHEV, BAS+, etc. Choose Thermal Architecture Similar to the Proposed Vehicle - i.e., cabin volume, rear evaporator, chiller, ducting, solar load and occupant solar impingement, etc. Select Competitive Benchmark Select a Vehicle from the Program Teams Competitive Set Select a Vehicle with a Simila
16、r Thermal Architecture as the Proposed Vehicle - i.e., cabin volume, rear evaporator, chiller, ducting, solar load and occupant solar impingement, etc. Ensure the Benchmark Vehicles HVAC System is Well Received by the Public - JD Power IQS, JD Power Appeal, Consumer Reports, etc. Establish VTS Targe
17、ts Compare Benchmark and GM Baseline to Derive VTS Targets (see Appendix A, Data Sheet A7) Compare Vehicle Attributes (i.e., cabin volume, glass surface area/angle, roof area) Compare Air Delivery System Compare Thermal System Performance During Both GMW3037 and GMW3202 Decision Analysis Use Decisio
18、n Analysis Table (see Appendix A, Data Sheet A7) Create SSTS and VTS Targets Verify that VTS Targets are Achievable with an e-Thermal Analysis Provide VTS Targets to the Design Lead Engineer Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWID
19、E ENGINEERING STANDARDS GMW16767 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 3 of 16 3.5.2 Human thermal comfort is externally dependent on solar radiation (direct solar impingement and local hot surfaces), localized ambient temperature, and localized convective airflo
20、w. Further, convective airflow localized around the occupants is dependent on A/C outlet placement (orientation, blockage and distance from occupant), number of occupants and cabin size. Cabin size impacts the time to occupant comfort due to both the effective thermal mass of the passenger compartme
21、nt and the heat exchange of the cabin with the external environment. In brevity, the intention of this analysis is to select component performance attributes based on a desired evaporator heat rejection (see Appendix A, A2.1). A Decision Analysis in Appendix A, Data Sheet A7, is used to assist in de
22、termining VTS targets. 3.5.3 Proposed comparison vehicles with glass surface area and/or angle of the glass (occupant impingement) more than 15% different from the GM baseline and or competitive benchmark, require a correction factor applied to the evaporator heat rejection. (See Appendix A, A3). A
23、vehicle with third row occupants requires a third row air distribution system as occupants cannot find comfort in minimal convective airflow. Furthermore, ensure the cabin volume of the GM baseline and the competitive vehicles are of similar size due to the thermal mass and exterior heat exchange di
24、fferences. Correction factor error increases as the difference from the baseline vehicle increase. The accurate selection of a GM baseline vehicle is, therefore, of critical importance. See Data Sheets A1, A2, A3, A4, A5 and A6 regarding specific conditions to be collected, and record the informatio
25、n as shown. 3.6 Personnel/Skills. The engineer conducting this analysis should be skilled in the following. Thermodynamics and Heat Transfer. Automobile Air Conditioning Systems Analysis. Utilization of e-Thermals Refrigerant Cycle Tool. Building and Using e-Thermal Air Conditioning Models. 4 Proced
26、ure This is a four step analysis process designed to predict air conditioning system performance. This analysis should be refined as information becomes available and should be kept up-to-date. The output of this coarse analysis process shall be used to populate the Subsystem Technical Specification
27、 (SSTS) and Component Technical Specification (CTS). See Figure 2. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16767 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 4 of 16 Figure 2
28、: Air Conditioning System Performance Analysis 4.1 Preparation. 4.1.1 Available Component Data Sheets (CDS) should be collected at least two weeks prior to beginning this procedure. This should provide enough time to verify the accuracy of the CDS. When CDS are not available, then components within
29、the e-Thermal database may suffice. 4.1.2 An adjustment to the system airflow may be necessary if the proposed architecture has substantially more glass surface area than the Competitive Benchmark. (See Appendix A, A3). Airflow is impacted by evaporator face area. Once evaporator geometry becomes de
30、fined, system airflow should be studied to understand the sensitivity of evaporator face area. 4.2 Conditions. 4.2.1 Environmental Conditions. See Table 1 for analysis input boundary conditions. Table 1: Ambient Boundary Conditions for Refrigerant Cycle Analysis Calculate System Requirements Utilizi
31、ng e-Thermals Refrigeration Cycle Tool Calculate evaporator heat rejection based on competitive benchmarking (Appendix A, A2.1) Calculate compressor mass flow rate to specify out a compressor to meet the systems VTS Calculate condenser heat rejection to specify a condenser to meet the systems needs
32、System Sensitivity Analysis Build an e-Thermal Air Conditioning Model with the Components Selected Above Sweep compressor speed: Hybrid (4500 to 8500) |Conventional (750 to 2750) Sweep condenser airflow: 50 kph (20 to 70 CMM) | Idle (20 to 70 CMM) Sweep evaporator volumetric airflow: 50 kph (95 to 1
33、35 L/s) | Idle (95 to 135 L/s) Select Components Utilize an e-Thermal Air Conditioning Model to Select A/C Components from Database With the recommended components predict system performance utilizing the prescribed boundary conditions in Section 4.2.1 If the target requirements cannot be met, the a
34、nalyst should provide alternatives which may provide similar performance Compare to Competitive Benchmark Compare the Competitive Benchmark and the GM Baseline to Proposed Design Simulate a GMW3037 test procedure within e-Thermal with proposed design Tune cabin model to ensure thermal capacitance of
35、 the model is similar to the GM baseline Compare cooldown rate and idle performance to VTS targets For a hybrid propulsion architecture, check condenser air out temperature requirement Ambient 50 km/h Sizing Point Idle Sizing Point Evaporator Air In Temperature 38 C 28 C Evaporator Air In Relative H
36、umidity 40% 50% Condenser Air In Temperature 38 C 50 C Ram Air Speed 50 km/h 0 km/h Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16767 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page
37、 5 of 16 4.2.2 Test Conditions. Deviations from the requirements of this standard shall have been agreed upon. Such requirements shall be specified on component drawings, test certificates, reports, etc. See Table 2 for analysis output boundary conditions. Table 2: System Boundary Conditions for Ref
38、rigerant Cycle Analysis Operating Point 50 km/h Sizing Point Idle Sizing Point VTS Evaporator Airflow Target See Appendix A, A.1.1 for the Default See Appendix A, A.1.1 for the Default VTS Vent Air Out Target Temperature 11 0.5 C 11 0.5 C VTS Headliner Air Out Target Temperature 12 0.5 C 12 0.5 C A/
39、C Coefficient of Performance (COP) Target 2.0 1.8 Compressor In Pressure 200 KPaG (200 KPaG Hybrid) 300 KPaG (260 KPaG Hybrid) Compressor Out Pressure 1750 KPaG (1650 KPaG Hybrid) 2100 KPaG (1800 KPaG Hybrid) Evaporator Out Superheat 8 K 4 K Compressor Displacement See Appendix A, A.1.1 for the Defa
40、ult See Appendix A, A.1.1 for the Default Condenser Volumetric Airflow See Appendix A, A.1.1 for the Default See Appendix A, A.1.1 for the Default Condenser Out Refrigerant Subcooling 8 K 4 K Condenser Refrigerant Pressure Drop 66 kPa 36 kPa Evaporator Refrigerant Pressure Drop 56 kPa 31 kPa Front S
41、uction Line Pressure Drop 21 kPa 7 kPa Front Suction Line Heat Pick-Up 1 C 3 C Rear Suction Line Pressure Drop 35 kPa 14 kPa Rear Suction Line Heat Pick-Up 1 C 4 C Note: Boundary conditions are not program requirements. Program requirements are discussed in Figure 1 - Process to Establish Vehicle Te
42、chnical Specification (VTS) Targets. Boundary conditions do not consider usage of an Internal Heat Exchanger (IHX). An IHX can be included in an analysis once a specific evaporator has been sourced. 4.3 Instructions. 4.3.1 Utilize e-Thermals Refrigerant Cycle Tool. Open e-Thermal System Simulation P
43、rogram. Select HVAC in the menu bar, and select Refrigeration Cycle from the pull down menu. A screen like the one presented in Figure 3 will appear. For dual evaporator systems or evaporator/chiller systems, one must move directly to 4.3.2. The refrigerant cycle tool cannot be used to select compon
44、ents for a dual evaporator system or an evaporator/chiller system. (See Appendix A, A4 for instructions). Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16767 Copyright 2012 General Motors Company All Rights Res
45、erved August 2012 Page 6 of 16 Figure 3: e-Thermals Refrigerant Cycle Tool Example of a 50 km/h Sizing Point 4.3.2 Create an e-Thermal Air Conditioning Model. Although e-Thermals refrigeration cycle tool provides insight into the behavior of an air conditioning system, an e-Thermal air conditioning
46、model is required to check the interaction of the components (see Figure 4).The refrigeration cycle tool above requires the user to make numerous assumptions, whereas the air conditioning cycle does not. Within Appendix A (see A5), one can find a link for a procedure describing the building a generi
47、c air conditioning model. Figure 4: e-Thermals Air Conditioning Model 4.3.3 System Sensitivity Analysis. It is important to understand what limits the performance of proposed air conditioning system. If the system architect understands the limiting factors of the system, then architect can design an
48、d negotiate around those shortcomings. Within Appendix A (see A6), one can find complete Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16767 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 7 of 16 instructions on how to conduct sensitivity sweeps on an air conditioning system. The most common performance based sensitivity sw
