Browse Topic: Refrigerants

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Automotive Refrigerant Recovery/Recycling/Recharging Equipment Intended for use with Both R-1234yf and R-134aJ3030_202011 (Current)11/13/2020
The purpose of this SAE Standard is to establish the specific minimum equipment requirements for recovery/recycling/recharge equipment intended for use with both R-1234yf and R-134a in a common refrigerant circuit that has been directly removed from, and is intended for reuse in, mobile air-conditioning (A/C) systems. This document does not apply to equipment used for R-1234yf and R-134a having a common enclosure with separate circuits for each refrigerant, although some amount of separate circuitry for each refrigerant could be used.
Interior Climate Control Service Committee
Safety and Design Standards for Motor Vehicle Refrigerant Vapor Compression SystemsJ639_202011 (Current)11/9/2020
This SAE Standard applies to refrigerant vapor compression systems that provide cooling and/or heating for passenger cars, light trucks, and commercial vehicles (on and off road) that use automotive type mobile air conditioning (MAC) systems. Large trucks, buses, and other vehicles that do not use typical automotive A/C systems or use refrigerants not listed in this document are not covered by this standard. This standard covers vehicles with MAC systems using belt driven compressors and electric motor driven compressors. This document provides industry-recognized standards for the design, assembly, and test of MAC systems, including necessary service equipment, and is intended to cover all phases of the lifetime of MAC systems to minimize environmental, health, and safety impacts. The standards listed in this document cover the currently accepted industry guidelines and procedures. The standards can be used as requirements for regulatory authorities to meet minimum environmental, health, and safety requirements. Also included are cautionary statements for the service industry to alert technicians to the inadvisability and possible health or safety effects associated with venting refrigerant during service. It is not intended to restrict the use, or further development of, other types of refrigerants or refrigeration systems for MAC applications. This document may be amended, or additional safety standards created, should other refrigerants or refrigeration systems become practical. This document addresses only HFC-134a (R-134a), carbon dioxide (R-744), HFO-1234yf (R-1234yf), and HFC-152a (R-152a) refrigerants. For R-152a refrigerants, this standard will only apply to secondary loop systems. To prevent system contamination, all refrigerants used in MAC vapor compression systems require unique service fittings and service equipment. The unique service fittings are intended to significantly reduce the potential for refrigerant cross-contamination during service activities. CFC-12 (R-12) is no longer in use in new MAC systems. The service fitting description is maintained as a reference for older vehicles still in use. When retrofitting an R-12 system to use R-134a or when removing R-12 (during vehicle disposal), use service equipment designed for R-12 and certified to meet the requirements of SAE J1990 (R-12 recovery and recycle equipment).
Interior Climate Control Vehicle OEM Committee
Standard for Refrigerant Risk Analysis for Mobile Air Conditioning SystemsJ2773_202005 (Current)5/15/2020
This SAE Standard describes methods to understand the risks associated with vehicle mobile air conditioning (MAC) systems in all aspects of a vehicle’s lifecycle including design, production, assembly, operation, and end of life. Information for input to the risk assessment is provided in the appendices of this document. This information should not be considered to be complete, but only a reference of some of the data needed for a complete analysis of the risk associated with the use of refrigerants in MAC systems.
Interior Climate Control Vehicle OEM Committee
Alternatives to Cadmium PlatingAIR4160B (Current)3/24/2020
To document and provide access to information obtained by an industry survey.
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
HFC-134a (R-134a) Recovery/Recycle/Recharging Equipment for Mobile Air-Conditioning SystemsJ2788_202001 (Historical)1/3/2020
The purpose of this SAE Standard is to establish the specific minimum equipment performance requirements for recovery and recycling of HFC-134a that has been directly removed from, and is intended for reuse in, mobile air-conditioning (A/C) systems. It also is intended to establish requirements for equipment used to recharge HFC-134a to an accuracy level that meets Section 9 of this document and SAE J2099. The requirements apply to the following types of service equipment and their specific applications. a Recovery/recycling equipment b Recovery/recycling-refrigerant charging c Refrigerant recharging equipment only
Interior Climate Control Service Committee
Measurement of Passenger Compartment Refrigerant Concentrations Under System Refrigerant Leakage ConditionsJ2772_201909 (Current)9/3/2019
This Standard is restricted to refrigeration circuits that provide air-conditioning for the passenger compartments of passenger and commercial vehicles. This Standard includes analytical and physical test procedures to evaluate refrigerant concentration inside the passenger compartment. In the early phases of vehicle evaluation, usage of the analytical approach may be sufficient without performing physical tests. The physical test procedure involves releasing refrigerant from an external source to a location adjacent to the evaporator core (inside the HVAC module). An apparatus is used to provide a repeatable, calibrated leak rate. If the system has multiple evaporators, leakage could be simulated at any of the evaporator locations. This standard gives detail information on the techniques for measuring R-744 (CO2) and R-1234yf (HFO-1234yf), but the general techniques described here can be used for other refrigerants as well.
Interior Climate Control Vehicle OEM Committee
R-1234yf (HFO-1234yf) Recovery/Recycling/Recharging Equipment for Flammable Refrigerants for Mobile Air-Conditioning SystemsJ2843_201907 (Current)7/15/2019
This SAE Standard applies to equipment to be used with R-1234yf refrigerant only. It establishes requirements for equipment used to recharge R-1234yf to an accuracy level that meets Section 9 of this document and purity levels defined in SAE J2099. Refrigerant service equipment is required to ensure adequate refrigerant recovery to reduce emissions and provide for accurate recharging of mobile air conditioning systems. Equipment shall be certified to meet all performance requirements outlined in this document and international/regional construction and safety requirements as outlined in this document.
Interior Climate Control Service Committee
R-1234yf and R744 Design Criteria and Certification for OEM Mobile Air Conditioning Evaporator and Service ReplacementsJ2842_201906 (Historical)6/25/2019
The intent of this standard is to establish a framework to assure that all evaporators for R-744 and R-1234yf mobile air conditioning (MAC) systems shall meet appropriate testing and labeling requirements. SAE J639 requires an assement to be performed to minimize reasonable risks in MAC systems. The evaporator (as designed and manufactured) shall be part of that risk assessment, and it is the responsibility of the vehicle manufacturer to assure all relevant aspects of the evaporator are included. It is the responsibility of all vehicle or evaporator manufacturers to comply with the standards of this document at a minimum. (Substitution of specific test procedures by vehicle manufactures that correlate well to field return data is acceptable.) As appropriate, this standard can be used as a guide to support risk assessments. With regard to certification, most vehicle manufacturers have established formal production part approval processes (PPAP) where compliance certification is established and formally documented. For an evaporator manufacturer of non-original equipment parts (or a vehicle manufacturer that does not have a formal part compliance certification process), then the certification described in this standard is the requirement to which those evaporators shall comply. In this case, the evaporator manufacturer or an independent institution shall complete the evaporator certification according to SAE J2911. An example of the latter would be the completion of witness testing by the evaporator manufacturer with the submission of certification documents by the witness organization. Refrigerant R-152a was excluded from this standard because a secondary loop refrigerant system is required. This standard also does not apply to R-134a refrigerant evaporators because it is proven in use.
Interior Climate Control MAC Supplier Committee
HFC-134a Refrigerant Electronic Leak Detectors, Minimum Performance CriteriaJ2791_201903 (Current)3/20/2019
This SAE Standard provides testing and functional requirements to meet specified minimum performance criteria for electronic probe-type leak detectors. So they will identify smaller refrigerant leaks when servicing all motor vehicle air conditioning systems, including those engineered with improved sealing and smaller refrigerant charges to address environmental concerns and increase system efficiency. This document does not address any safety issues concerning their design or use.
Interior Climate Control Service Committee
R-1234yf Service Hose, Fittings and Couplers for Mobile Refrigerant Systems Service EquipmentJ2888_201902 (Current)2/11/2019
This SAE Standard covers fittings, couplers, and hoses intended for connecting service hoses from mobile air-conditioning Systems to service equipment such as charging, recovery and recycling equipment. (Figure 1) This specification covers service hose fittings and couplers for MAC service equipment service hoses, per SAE J2843 and SAE J2851, from mobile air-conditioning systems to service equipment such as manifold gauges, vacuum pumps, and air-conditioning charging, recovery and recycling equipment.
Interior Climate Control Service Committee
Performance Characteristics of a Mobile Heat Pump System at Low Ambient Temperature2018-01-00764/3/2018
The demand for mobile heat pump systems increases with the growing popularity of electric vehicles. One big challenge of such systems using low pressure refrigerant is the substantial drop of heating capacity at low ambient temperature conditions, when heat is most needed. The low suction density associated with low operating pressure in the evaporator is the major reason for the capacity drop. In extremely low ambient temperature, compressor speed may need to be regulated in order to prevent suction pressure going below atmospheric pressure, hence further reducing heat pumping capability. Other factors like pressure drop induced temperature glide and refrigerant maldistribution in the outdoor evaporator also weakens the system ability to absorb heat from ambient air. This paper presents detailed and in-depth analysis of the performance and limiting factors on low ambient temperature operation of a mobile heat pump system using refrigerant R1234yf. Experimental data are taken for ambient temperatures ranging from −20 to 20 ˚C. Analysis of losses are presented with the aid of a simulation model.
Feng, Lili, Hrnjak, Predrag
AVIONICS REFRIGERATION COOLING SYSTEMARINC728 (Current)10/27/2017
This standard provides standards for the in accordance with which aircraft operators and manufacturers can order avionics refrigeration units and can design installations for an ARCS.
Airlines Electronic Engineering Committee
Effect of Magnetic Nanorefrigerant on Electric Vehicle2017-01-222210/8/2017
The ever increasing popularity of electric vehicles and higher requirement on safety and comfort has led heat pump air conditioning system indispensable in electric vehicle. Many studies have shown that the addition of nano particles contributes to great improvement on thermal conductivity than that of conventional refrigerants. Therefore, the application of the magnetic nanorefrigerant in heat pump air conditioning system has massive potential to heighten the heat transfer efficiency. This paper aims at studying the magnetic nanorefrigerant comprised of the magnetic nano powder Fe3O4 and refrigerant R134a. According to the relevant theoretical analyses and empirical formula, the heat transfer coefficient, density, viscosity, and other physical parameters are calculated approximately. In the heat pump air conditioning system of a certain type of electric vehicle, the special working condition parameters are selected to carry out calculation analysis with numerical analysis software. The results show that the heat exchange amount of this nanorefrigerant is 21.23% higher than the pure refrigerant R134a and increases with the volume fraction of the nano particles. Moreover, after adding Fe3O4 nano materials to the heat pump air conditioning system, the efficiency of this system has been increased by 8.6%. So the conclusion can be drawn that appliance of the nano-refrigerant in electric vehicle is both effective and feasible.
Liu, ZhenYang, Wang, Xihui
Research on the Application of Micro-Channel Evaporator in R134a Roof-Top Bus Air Conditioner2017-01-01613/28/2017
This study investigates the cycle performance and potential advantages of the replacement of fin-and-tube evaporator with parallel flow micro-channel evaporator, in R134a roof-top bus air conditioner (AC) system. The heat exchangers for bus AC system are featured by a stringent space height limitation. The configuration of inclined four piece or six piece micro-channel evaporators was proposed to satisfy this space requirement, instead of original two piece fin-and-tube evaporators. Additionally, the individual superheat control method with thermostatic expansive valve (TXV) in each evaporator was adopted to improve refrigerant distribution. Three kinds of micro-channel evaporators were designed and equipped in an 8-m roof-top bus AC system. Except the replacement of evaporators, TXV and connecting pipes, other cycle components were kept same. Comparison experiments were carried out to evaluate the cycle performance with micro-channel evaporator configuration in psychometric calorimeter test facility at rated cooling condition. Experiment results, including R134a refrigerant charge, superheat performance, cooling capacity and system coefficient of performance (COP) were compared between micro-channel evaporator system and fin-and-tube evaporator system. Results show that individual superheat control method improved the superheat distribution uniformity among multiple evaporators, and enhanced the system cooling capacity. Besides, the optimum micro-channel evaporator configuration achieved equal cooling capacity and COP with fin-and-tube evaporators. Furthermore, potential advantages including refrigerant charge reduction, cost saving, system mass reduction, and compact installation were also discussed for the application of micro-channel evaporator in roof-top bus AC system.
Wang, Dandong, Liu, Cichong, Chen, Jiangping
Effects of Thinner Condenser Technology on Vehicle AC Pull Down Performance2017-01-01663/28/2017
The effects of substituting a 12 mm thick subcool on top condenser in place of a 16 mm subcool on bottom condenser are evaluated in a vehicle level AC pull down test. The A to B testing shows that a thinner condenser with subcool on top exhibits no degradation in AC performance while resulting in a lower total system refrigerant charge. The results are from vehicle level tests run in a climatically controlled vehicle level wind tunnel to simulate an AC pull down at 43°C ambient. In addition to cabin temperature and AC vent temperatures, comparison of compressor head pressures was also done. The conclusion of the study was that a standard 16 mm thick subcool on bottom IRD condenser can be replaced by a 12 mm thick subcool on top IRD condenser with no negative effects on performance.
Pandit, Noori
Refrigerant Charge Imbalance in a Mobile Reversible Air Conditioning-Heat Pump System2017-01-01773/28/2017
This paper presents the study of refrigerant charge imbalance between A/C (cooling) mode and HP (heating) mode of a mobile reversible system. Sensitivities of cooling and heating capacity and energy efficiency with respect to refrigerant charge were investigated. Optimum refrigerant charge level for A/C mode was found to be larger than that for HP mode, primarily due to larger condenser size in A/C mode. Refrigerant charge retention in components at both modes were measured in the lab by quick close valve method. Modeling of charge retention in heat exchangers was compared to experimental measurements. Effect of charge imbalance on oil circulation was also discussed.
Feng, Lili, Hrnjak, Predrag
NVH Challenges with Introduction of New Refrigerant HFO-1234yf2017-01-01723/28/2017
The refrigerant transition from HFC-134a to HFO-1234yf has proven to be more challenging on controlling refrigerant flow-induced noises generated from automotive air-conditioning (A/C) systems than originally anticipated. The objectives of this paper are to describe the noise issues with HFO-1234yf, understand the mechanisms and key factors affecting HFO-1234yf refrigerant flow-induced noise. Finally, the countermeasures and guidelines for attenuating and suppressing the noise are presented.
Venkatappa, Suhas, Koberstein, Manfred, Liu, Zhengyu
R-1234yf [HFO-1234yf] Refrigerant Electronic Leak Detectors, Minimum Performance CriteriaJ2913_201610 (Current)10/20/2016
This SAE Standard provides testing and functional requirements to meet specified minimum performance criteria for electronic probe-type leak detectors. The equipment specified here will identify smaller refrigerant leaks when servicing motor vehicle air conditioning systems, including those engineered with improved sealing and smaller refrigerant charges to address environmental concerns and increase system efficiency. This document does not address any safety issues concerning the equipment design or use beyond that of sampling a flammable refrigerant save those described in 3.1 and 3.2 of this document. All requirements of this standard shall be verified in SAE J2911.
Interior Climate Control Service Committee
Experimental Evaluation of an Automobile Air - Conditioning System with and without Liquid Suction Heat Exchanger2016-01-91105/18/2016
This study involves the experimental aspects of R134a Automobile Air Conditioning (AAC) system with & without Liquid Suction Heat Exchanger (LSHX). To evaluate the performance of an Automobile Air Conditioning system, an experimental system consisting of original components from an R134a Automobile Air Conditioning system has been set up and instrumented. An additional Liquid Suction Heat Exchanger is used in conventional Automobile Air Conditioning system. Effect of evaporator temperature variation & compressor speed variation on R134a Automobile Air Conditioning system performance is evaluated. From experimental evaluation, it is derived that there is a Coefficient of Performance (COP) improvement in Automobile Air Conditioning system with Liquid Suction Heat Exchanger compared to Automobile Air Conditioning system without Liquid Suction Heat Exchanger. Performance of an R134a Automobile Air Conditioning system degrades with increase in compressor speed. From refrigerant side, it is concluded that overall Coefficient of Performance improvement is about 2.54% with Liquid Suction Heat Exchanger with 45.83% effectiveness. From air side calculation, it is found that Coefficient of Performance improvement is about 7.51% in Automobile Air Conditioning system with Liquid Suction Heat Exchanger compared to Automobile Air Conditioning system without Liquid Suction Heat Exchanger.
Vaghela, Jignesh
Validation of a CFD Model to Predict R-1234yf Concentrations in a Vehicle Cabin Compartment2016-01-02214/5/2016
The adoption of a low-GWP refrigerant gas in MAC systems is mandatory from January 1st, 2017 according to the European Directive 2006/40/EC requirements for all new passenger cars, in order to gain their registration in the EU28 market. Following the work carried out in 2008 to support the FCA choice for the new types development, a further step was accomplished to evaluate the risk involved by the adoption of the low-GWP refrigerant gas R-1234yf in the MAC systems. This paper is focused on the activities held to enhance the 3D CFD method and its validation. In certain concentrations, R-1234yf could present a safety hazard to the vehicle occupants and, according to the ISO Standard Risk Scenario evaluation, 3D CFD tools are adopted to evaluate the ignition event associated with small or large leak in the passenger compartment. The method validation has been supported by both a simplified control volume “dummy cabin compartment” and an actual FCA vehicle. Methods have been used to measure the actual R-1234yf concentrations due to a complete system charge leakage in an HVAC configuration representative of the worst case operating conditions.
Monforte, Roberto, Mattiello, Fabrizio, Perosino, Andrea, Porta, Fabrizio, Paz, Susanna, Lopez del Rincón, Pablo
Refrigerant-Oil Flow at the Compressor Discharge2016-01-02474/5/2016
Automotive air conditioning compressor produces an annular-mist flow consisting of gas-phase refrigerant flow with oil film and oil droplets. This paper reports a method to calculate the oil retention and oil circulation ratio based on oil film thickness, wave speed, oil droplet size, oil droplet speed, and mass flow rate. Oil flow parameters are measured by high-speed camera capture and video processing in a non-invasive way. The estimated oil retention and oil circulation ratio results are compared quantitatively with the measurements from system experiments under different compressor outlet gas superficial velocity. The agreement between video result and sampling measurement shows that this method can be applied in other annular-mist flow analysis. It is also shown that most of the oil exists in film from the mass point of view while oil droplets contributes more to the oil mass flow rate because they travel in a much higher speed.
Xu, Jiu, Hrnjak, Predrag
Experimental Study of an Air Conditioning-Heat Pump System for Electric Vehicles2016-01-02574/5/2016
This paper presents the experimentally obtained performance characteristics of an air conditioning-heat pump system that uses heat exchangers from a commercially available Nissan Leaf EV. It was found that refrigerant charge needed for cooling operation was larger than that for heating function with the test setup. The effects of: a). indoor air flow rate, b). outdoor air flow rate, and c). compressor speed on heating capacity and energy efficiency were explored and presented. Appropriate opening size of expansion valve that controlled subcooling for better energy efficiency was discussed and results were presented. Expansion valve opening size also strongly affected charge migration. Warm-up tests at different ambient conditions showed the necessity of a secondary heater to be reserved for very low ambient temperature.
Feng, Lili, Hrnjak, Predrag
Flow-Induced Gurgling Noise in Automotive Refrigerant Systems2015-01-22766/15/2015
Refrigerant flow-induced gurgling noise is perceived in automotive refrigerant systems. In this study, the condition of the gurgling generation is investigated at the vehicle level and the fundamental root cause is identified as the two-phase refrigerant flow entering the TXV for system equipped with variable displacement compressors. By conducting literature reviews, the acoustic characteristics of the flow patterns and the parameters affecting the flow regimes in horizontal and vertical tubes are summarized. Then the gurgling mechanism is explained as the intermittent flow is developed at the evaporator inlet. In the end, the improved and feasible design for avoiding the intermittent flow (slug, plug or churn flow) or minimizing its formation is proposed and verified in refrigerant subsystem (RSS) level. Finally, the guidelines for the attenuation and suppression of the gurgle are provided.
Liu, Zhengyu, Wozniak, Donald, Koberstein, Manfred, Jones, Curtis, Xu, Jan, Venkatappa, Suhas
Flow-Induced Whistle in the Joint of Thermal Expansion Valve and Suction Tube in Automotive Refrigerant System2015-01-22756/15/2015
In the thermal expansion valve (TXV) refrigerant system, transient high-pitched whistle around 6.18 kHz is often perceived following air-conditioning (A/C) compressor engagements when driving at higher vehicle speed or during vehicle acceleration, especially when system equipped with the high-efficiency compressor or variable displacement compressor. The objectives of this paper are to conduct the noise source identification, investigate the key factors affecting the whistle excitation, and understand the mechanism of the whistle generation. The mechanism is hypothesized that the whistle is generated from the flow/acoustic excitation of the turbulent flow past the shallow cavity, reinforced by the acoustic/structural coupling between the tube structural and the transverse acoustic modes, and then transmitted to evaporator. To verify the mechanism, the transverse acoustic mode frequency is calculated and it is coincided to the one from measurement. In the end, the recommendations for preventing the system from having whistle are also provided.
Koberstein, Manfred, Liu, Zhengyu, Jones, Curtis, Venkatappa, Suhas
Numerical Investigation of the Effect of Microchannel Evaporator Design on the Performance of Two-Phase Ejector Automotive Air Conditioning Cycles2015-01-03624/14/2015
Much attention has been given in recent years to the use of two-phase ejectors and particularly to the performance of the standard ejector cycle with a liquid-vapor separator. However, this cycle may not be the best choice for automotive applications due to the large size required by an efficient separator as well as the cycle's performance at conditions of lower ejector potential. A limited amount of recent research has focused on alternate two-phase ejector cycles that may be better suited for automotive applications. One of these cycles, using the ejector to allow for evaporation at two different temperatures and eliminating the need for a separator, will be the subject of investigation in this paper. Previous investigations of this cycle have been mainly theoretical or experimental; this paper aims to provide a numerical analysis of the effect of evaporator design on the performance of the ejector cycles. In this paper, a numerical model of a microchannel evaporator is developed and incorporated into thermodynamic models of the standard and alternate two-phase ejector cycle. R134a is used as the working fluid, though the results could be expanded to R1234yf due to the similar properties of the two fluids. Data from the authors' previous experimental investigation of the alternate ejector cycle is used to validate the numerical model. The evaporator model for the alternate cycle is modified to allow for two different evaporation temperatures. The effect of the ratio of low-temperature to high-temperature evaporator area on the performance of the cycle is explored, and comparison is made between the performance of the alternate ejector cycle and the standard ejector cycle. The effect of operation at conditions of lower ejector potential, or reduced ejector efficiency, on the performance of the ejector cycles is also investigated, and both cycles are compared to a baseline cycle without an ejector in order to obtain a realistic idea of the improvement that can be achieved with ejector air conditioning cycles. It is seen that evaporator design, not just ejector design, can have a significant effect on the COP of ejector cycles.
Lawrence, Neal, Elbel, Stefan
An Infrared Thermography Based Method for Quantification of Liquid Refrigerant Distribution in Parallel Flow Microchannel Heat Exchanger2015-01-03574/14/2015
This paper presents a method of utilizing infrared images to quantify the distribution of liquid refrigerant mass flow rate in microchannel heat exchangers, which are widely used in automobile air conditioning systems. In order to achieve quantification, a relationship is built between the liquid mass flow rate through each microchannel tube and the corresponding air side capacity calculated from the infrared measurement of the wall temperature. After being implemented in a heat exchanger model, the quantification method is validated against experimental data. This method can be used for several types of heat exchangers and it can be applied to various heat exchanger designs.
Li, Huize, Hrnjak, Predrag
An Experimentally Validated Model for Predicting Refrigerant and Lubricant Inventory in MAC Heat Exchangers2014-01-06944/1/2014
The paper presents a semi-empirical model to predict refrigerant and lubricant inventory in both evaporator and condenser of an automotive air conditioning (MAC) system. In the model, heat exchanger is discretized into small volumes. Temperature, pressure and mass inventory are calculated by applying heat transfer, pressure drop and void fraction correlations to these volumes respectively. Refrigerant and lubricant are treated as a zeotropic mixture with a temperature glide. As refrigerant evaporates or condenses, thermophysical properties are evaluated accordingly with the change of lubricant concentration. Experimental data is used to validate the model. As a result, refrigerant and lubricant mass is predicted within 20% in the evaporator. However, in the condenser, lubricant mass was consistently under-predicted while refrigerant mass was predicted within 15% error. Moreover, the lubricant under-prediction becomes more significant at higher Oil Circulation Ratio (OCR). The analysis showed that the lubricant is separated from the flow in the condenser header and starts to accumulate in the bottom channels. The temperature profile in the infrared image supports this hypothesis, as the temperature of the bottom channels is much lower. After correcting this by counting in the bottom lubricant mass, the model predicts condenser lubricant mass consistently within 15% error.
Jin, Shenghan, Hrnjak, Predrag
Ways to Determine Vehicle Dual AC System Charge Level2014-01-06974/1/2014
This paper addresses various ways to determine vehicle dual AC system charge level. Traditionally, either checking charge level plateau and/or using the certain condenser outlet subcooling magnitude are adopted to determine AC system charge level. It is challenging to determine refrigerant charge level in the following scenarios: (1) Some AC systems do not exhibit the flatted charge plateau. (2) The condenser outlet subcooling continues to rise. (3) The system has the requirements to run both front and aux evaporators, front evaporator only and aux evaporator only. It was found that compressor compression ratio of absolute discharge pressure to absolute suction pressure always presents the bath tub curve for all AC systems. When the system reaches the optimal charge level, the evaporator air outlet temperatures show the stable trend. In addition to the traditional condenser subcooling method, few approaches are presented in the paper. One way to determine the dual evaporator system charge level is: checking compressor compression ratios vs. charge level on the tests with (1) running both front and aux evaporators, (2) running front evaporator only (aux evaporator off). In addition, checking front evaporator discharge air temperature is introduced. The second way to determine the dual evaporator system charge level is: using compressor refrigerant density ratio of discharge to suction vs. charge level. The third way to determine the dual evaporator charge level is: using AC system unit energy efficiency vs. charge level and compressor mass flowrate vs. charge level. By adding more depth analyses on system and compressor behaviors, the optimal charge of the dual evaporator system becomes an obvious selection when there is a challenge in using the traditional condenser subcooling method.
Zheng, Yinhua
Effect of Flow Regime in the Horizontal Inlet Header on Refrigerant-Oil Mixture Distribution in a MAC Microchannel Evaporator2014-01-07014/1/2014
The effect of lubricant on distribution is investigated by relating the flow regime in the horizontal inlet header and the corresponding infrared image of the evaporator. Visualization of the flow regime is performed by high-speed camera. R134a is used as the refrigerant with PAG 46 as lubricant, forming foam in all flow regimes. Quantitative information including foam location, foam layer thickness is obtained using a matlab-based video processing program. Oil circulation rate effect on flow regime is analyzed quantitatively.
Li, Huize, Hrnjak, Predrag
Crash Test with a Hot Operating Engine and R-1234yf MAC System2014-01-04204/1/2014
As part of the launch of the refrigerant R-1234yf there were a number of studies done regarding the ignition behavior of this new refrigerant in passenger cars. These tests were conducted by a number of automobile manufacturers, component suppliers, and the refrigerant supplier under laboratory conditions at the component and vehicle level. In November 2009 the international automotive industry concluded that the R-1234yf can be used safely in automotive air conditioning systems. Further tests were conducted by different automobile manufacturers, suppliers, and the refrigerant supplier under various laboratory and vehicle operation conditions means hot surfaces in the engine compartment. A number of vehicle manufactures have conducted full vehicle crash tests. In this paper, real world accidents are analyzed using the German In-Depth Accident Study (GIDAS) database as well as the thermal parameters for ignition of R-1234yf, i.e. concentration and surface temperature to create a worst-case scenario. These parameters were considered while conducting a frontal impact test with a hot 1.4 liter turbo gasoline engine with a critical overheated exhaust surface temperature and an operating R-1234yf Mobile Air Conditioning (MAC) system. The test was conducted with an ECE R95 deformable moving barrier at a test speed of 50kph.
Poklitar, Mathias, Seybold, Lothar
Passivation of Flexible YBCO Superconducting Current Lead With Amorphous SiO2 LayerTBMG-1744910/1/2013
Adiabatic demagnetization refrigerators (ADR) are operated in space to cool detectors of cosmic radiation to a few 10s of mK. A key element of the ADR is a superconducting magnet operating at about 0.3 K that is continually energized and de-energized in synchronism with a thermal switch, such that a piece of paramagnetic salt is alternately warm in a high magnetic field and cold in zero magnetic field. This causes the salt pill or refrigerant to cool, and it is able to suck heat from an object, e.g., the sensor, to be cooled. Current has to be fed into and out of the magnets from a dissipative power supply at the ambient temperature of the spacecraft. The current leads that link the magnets to the power supply inevitably conduct a significant amount of heat into the colder regions of the supporting cryostat, resulting in the need for larger, heavier, and more powerful supporting refrigerators. The aim of this project was to design and construct high-temperature superconductor (HTS) leads from YBCO (yttrium barium copper oxide) composite conductors to reduce the heat load significantly in the temperature regime below the critical temperature of YBCO.
Thermal Stabilization of Variable Loading, Multi-Evaporator Refrigeration Loops via Liquid Recirculation2013-01-22409/17/2013
Refrigeration systems with parallel evaporators are prone to systemic instabilities and thermal excursions, particularly under variable loading conditions. Conventional vapor compression systems require evaporators to discharge at very high vapor qualities to prevent liquid ingress to the compressor. This requires active control algorithms to regulate the flow to individual evaporators. This paper introduces a novel liquid recirculation loop that minimizes the effects of flow maldistribution and prevents dryout using passive components. The loop utilizes a refrigerant phase separator, in conjunction with passive inlet restrictions, to mitigate flow maldistribution and support larger evaporator mass flow rates corresponding to low-to-moderate exit qualities. With greater margin in exit quality before dryout occurs, thermal excursions at the evaporator outlets are readily avoided. Analysis of the flow redistribution for multi-evaporator systems subject to binary (on/off) loading conditions demonstrates the effectiveness of this system for static excursions. Experiments for a two-evaporator system with R134a as the working fluid demonstrate stable heat sink temperatures over a range of loading scenarios.
Fogg, David W., Chen, Weibo, Chambers, Rob
Refrigerant Charge Management and Control for Next-Generation Aircraft Vapor Compression Systems2013-01-22419/17/2013
Vapor compression systems (VCS) offer significant benefits as the backbone for next generation aircraft thermal management systems (TMS). For a comparable lift, VCS offer higher system efficiencies, improved load temperature control, and lower transport losses than conventional air cycle systems. However, broad proliferation of VCS for many aircraft applications has been limited primarily due to maintenance and reliability concerns. In an attempt to address these and other VCS system control issues, the Air Force Research Laboratory has established a Vapor Cycle System Research Facility (VCSRF) to explore the practical application of dynamic VCS control methods for next-generation, military aircraft TMS. The total refrigerant mass contained within the closed refrigeration system (refrigerant charge) is a critical parameter to VCS operational readiness. Too much or too little refrigerant can be detrimental to system performance. Extreme values of refrigerant charge can lead to a loss of evaporator temperature control, loss of high side pressure control, or other potentially catastrophic occurrences. The objective of this work is to examine real-time methods for determination of acceptable refrigerant charge in a prototypical VCS system, as a function of operational points, using only sensors already utilized in the control system (in-situ control sensors). It is envisioned that studies such as these can be used to guide development of a simple in-situ prognostic tool for system state-of-health indication (i.e. “Red Light, Yellow Light, Green Light”), with respect to level of charge, and to enable on-demand maintenance. Additionally, a method for continuous management of refrigerant charge as a means for optimizing system efficiency over a range of dynamic operating points is presented.
Puntel, Anthony, Emo, Stephen, Michalak, Travis E., Ervin, Jamie, Byrd, Larry, Tsao, Victor, Reitz, Thomas
High Efficiency Subcool Condenser2013-01-12954/8/2013
Sustainable reduction of the CO2 emissions of future vehicles goes hand in hand with the increase in efficiency of ancillary units. Of particular importance is the reduction of fuel consumption attributed to the vehicle's air conditioning system. The innovative development of a condenser with a 3-pass subcooling zone renders it possible to significantly increase the efficiency of the cooling circuit. This is applicable both in the case of current and future refrigerants. The basis for increasing the efficiency of the condenser is rooted in the systematic analysis of the local heat transfer functions, pressure drops and implementation of an improved flow path configuration. The current condenser design, which includes the functionality of a receiver/dryer with a dedicated subcooling zone, is effective at providing stable liquid refrigerant to the TXV under a variety of conditions. By optimally adapting the flow cross-section to the density change of the refrigerant and increasing the subcooling function by means of a 3-pass flow subcooling zone, it is possible to achieve a significantly lower outlet temperature of the refrigerant. The locally higher pressure drop in the subcooling zone does not have a negative impact on the vapor compression circuit and can therefore be used to increase efficiency without the risk of losses. The theoretical derivation, as well as simulation and measurement results for the new condenser, are presented and discussed in comparison with conventional designs. A new condenser specification has been derived and validated for the system-oriented evaluation of the component. Finally, the validation results from the circuit and vehicle measurements in the wind tunnel are presented. The newly developed condenser resulted in a significant increase of 4% of evaporator performance while maintaining mass and package space. Alternatively, weight and conduction depth can be reduced by 25% while maintaining capacity and system efficiency.
Wawzyniak, Markus, Walter, Christoph, Kemle, Andreas, David, Guillaume
Periodic Reverse Flow and Boiling Fluctuations in a Microchannel Evaporator of an R134a Mobile Air-Conditioning System2013-01-15004/8/2013
This paper presents experimental study of periodic reverse flow and induced boiling fluctuations in a microchannel evaporator and their impacts on performance of R134a mobile A/C system. Simultaneous flow visualization and pressure measurements revealed that reverse flow due to confined bubble longitudinal expansion caused periodic oscillations of the evaporator inlet pressure and the pressure drop, and their oscillation magnitude and frequency increase with ambient air temperatures because of higher average refrigerant mass flux and heat flux. Three potential impacts of vapor reverse flow reversal on evaporator performance are identified: 1) mild liquid maldistribution; 2) increased the evaporator pressure drop; 3) reduced heat transfer coefficient. Finally, to mitigate vapor reverse flow impacts, revised flash gas bypass (FGBR) method is proposed: vent and bypass backflow vapor trapped in the inlet header. Experimental results showed that system performances are further improved by an up to 5% higher capacity and an up to 3% higher COP.
Tuo, Hanfei, Hrnjak, Predrag
Experimental Measurements of Condensation Heat Transfer Coefficients for Refrigerant HFO-1234yf2013-01-14934/8/2013
Experimental tests were conducted on a parallel flow condenser with HFO-1234yf as the working fluid on an AC system bench to determine average and local heat transfer coefficients during condensation of HFO-1234yf for mass flow rates that are typically encountered from idle to highway speeds (800 to 3000 rpms). A condenser from MY 2008 medium-sized sedan was used for this investigation. All original OEM parts were used with the alternate refrigerant. Same TXV set-point was used with HFO-1234yf. The magnitude of the measured heat transfer coefficient for condensation was found to be 8~12% lower in comparison to HFC-134a. The magnitudes of the pressure drop during condensation were of the same magnitude as HFC-134a system. The information from this investigation can be used to in the design of condensers for mobile air conditioning systems with HFO-1234yf as the working fluid.
Mathur, Gursaran D.
Experimental and Analytical Investigation of Two-Phase Ejector Air-Conditioning Cycles Using Low-Pressure Refrigerants R134a and R1234yf2013-01-14954/8/2013
Two-phase ejectors have received increased attention in recent years because of their ability to improve the performance of automotive air-conditioning cycles by means of expansion work recovery. Much attention in recent years has been given to how high-pressure fluids, such as carbon dioxide, perform with ejector cycles; high-pressure fluids tend to have higher throttling loss, making them more attractive for expansion work recovery cycles, such as the two-phase ejector cycle. However, low-pressure fluids, such as those commonly used in automotive air-conditioning applications, tend to offer significantly lower work recovery potential. Nonetheless, the limited previous work on low-pressure refrigerants in ejector systems has shown that there is some improvement potential when using these fluids with ejector cycles. This paper presents the results of experimental and analytical investigations in which the performance of the low-pressure fluids R134a and R1234yf is compared between a conventional cycle without an ejector and several two-phase ejector cycles. An analytical comparison of the theoretical COP's and other practical advantages of several different twophase ejector refrigeration cycles is presented. An ejector cycle was constructed in which the pressure lift provided by the ejector was utilized in order to provide multiple evaporation temperatures. Multiple evaporators provide the potential for reduced exergetic losses between refrigerant and a single air stream as well as the possibility of cooling multiple air streams, which can be beneficial in some applications. Experimental results comparing the performance of the two fluids on the cycles are presented.
Lawrence, Neal, Elbel, Stefan
Effect of Lubricant on Two-phase Refrigerant Distribution in Microchannel Evaporator2013-01-15084/8/2013
This paper presents a model analysis of oil effects on the distribution of two phase refrigerant in a parallel flow microchannel evaporator. A microchannel evaporator model developed and presented earlier (SAE paper 2012-01-0321) is enhanced by inclusion of the thermodynamic and transport properties of refrigerant-oil mixture and their impact on boiling heat transfer and pressure drop characteristics. R134a and PAG oil are selected as the working pair. Viscosity effect and OCR effect on refrigerant distribution are investigated using this model, and the results show that 1) High viscosity is detrimental for refrigerant distribution. 2) As OCR increases, distribution becomes worse; but at very high OCR, distribution becomes better. Some initial experimental results show that distribution becomes worse when OCR changes from 0.1% to 3%.
Li, Huize, Hrnjak, Predrag
Alternatives to Cadmium PlatingAIR4160A (Historical)1/2/2013
To document and provide access to information obtained by an industry survey.
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
Automotive Engineering International 2012-09-1812AEID09189/18/2012
Sealing A/C systems Choosing the right automotive tube joint seal for HFO-1234yf refrigerant compatibility.
Minimum Performance Requirements for Non-Refrigerant Tracer Gasses and Electronic Tracer Gas Leak DetectorsJ2970_201207 (Historical)7/19/2012
This standard provides the testing and functional requirements guidance necessary for a leak detection device that uses any non-A/C refrigerant tracer gas, such as helium or a nitrogen-hydrogen blend, to provide functional performance equivalent to a refrigerant electronic leak detector. It explains how a non- refrigerant leak detector’s calibration can be established to provide levels of detection equal to electronic leak detectors that meet SAE J2791 for R-134a and SAE J2913 for R-1234yf.
Interior Climate Control Service Committee
High-Performance Micro-Porous Fluoropolymer Plastics for Critical ApplicationsTBMG-104697/1/2011
Polytetrafluoroethylene (PTFE) is a fully fluorinated polymer with exceptional chemical and physical properties: excellent chemical resistance, high temperature stability, good dielectric and nonstick properties and exceptional resistance to degeneration under severe conditions.
Lightweight Magnetic Cooler With a Reversible CirculatorTBMG-101435/25/2011
A design of a highly efficient and lightweight space magnetic cooler has been developed that can continuously provide remote/distributed cooling at temperatures in the range of 2 K with a heat sink at about 15 K. The innovative design uses a cryogenic circulator that enables the cooler to operate at a high cycle frequency to achieve a large cooling capacity. The ability to provide remote/distributed cooling not only allows flexible integration with a payload and spacecraft, but also reduces the mass of the magnetic shields needed.
R-1234yf Refrigerant Identifier Installed in Recovery and Recycling Equipment for Use With Mobile A/C SystemsJ2927_201102 (Historical)2/7/2011
This SAE standard applies to refrigerant identification equipment to be used for identifying an acceptable level of R-1234yf purity in a refrigerant tank or vehicle MAC system labeled as containing R-1234yf, and not misidentify other refrigerants, per 5.7.
Interior Climate Control Service Committee
Automotive Refrigerant Recovery/Recycling Equipment Intended for Use With Both R12 and R134aJ1770_201011 (Current)11/5/2010
The purpose of this SAE Standard is to establish the specific minimum equipment requirements for recovery/recycling equipment intended for use with both R12 and R134a in a common refrigerant circuit that has been directly removed from, and is intended for reuse in, mobile air-conditioning (A/C) systems. This document does not apply to equipment used for R12 and R134a having a common enclosure with separate circuits for each refrigerant.
Interior Climate Control Service Committee
HFC-134a Mobile Air Conditioning System Refrigerant Emission ChartJ2727_200808 (Historical)8/28/2008
The original SAE J2727 "Emission Chart" provided a rating system for comparing mobile A/C systems and was not intended to define mobile A/C system refrigerant emission. It had been developed from industry experience of expected system refrigerant emission based upon currently available technologies. The "System Emissions Chart" now contained in this revision is intended to serve as a means of estimating the annual refrigerant emissions rate (grams per year) from new production A/C systems equipped with specified component technologies. It provides emission values for various component technologies that are currently available, and can be expanded as new technologies are commercialized. This document provides the information to develop an Excel file template "System Emissions Chart" for system emission analysis. The chart includes automotive compressor technologies for conventional mobile air conditioning systems as well as those using semi-hermetic compressors. This standard can be considered a companion document to SAE J2763 Test Procedure for Determining Refrigerant Emissions from Mobile Air Conditioning Systems. SAE J2727 estimates system emissions, taking into account production assembly variation. SAE J2763 may be used to quantify emissions from properly assembled systems.
Interior Climate Control Fluids Committee
Developing Flow Map for Two-Phase R134a after Expansion Device2008-01-07364/14/2008
This paper presents a mapping of developing adiabatic two-phase R134a flow directly after the expansion valve until the flow is “fully developed” in a 15.3mm inner diameter pipe. Flow characteristics of separation distance, flow type in the homogenous region, void fraction as a function of tube length, and fully developed flow region void fraction and regime were quantified and described.
Bowers, Chad D., Hrnjak, Predrag S.
Automotive Engineering International 2007-10-01AUTOOCT0710/1/2007
After CD, what's next? Storing music in cars remains fraught with many engineering considerations as infotainment systems move into the next generation. Chevrolet Malibu General Motors has enhanced its midsize architecture for a more refined and luxurious ownership experience. Chrysler minivans Chrysler's family haulers feature a new look and more interior flexibility to go with a host of technology upgrades. Jaguar XF The company's middle sedan is updated with a 21st century interpretation of traditional standards. BMW M3 The high-performance version of the 3 Series coupe gets V8 power, other significant upgrades. Honda Accord The eighth generation of Honda's popular sedan offers more space, power, and safety. Fiat 500 The new car's styling harks back to the original of over 70 years ago, but it employs modern technology and shares a platform with the forthcoming Ford Ka replacement. Subaru Impreza The new model moves closer to the mainstream C-segment market, but a hatchback is added that will spawn the ultra-high-performance STi. Cooling off global warming potential There is still no decision on a new A/C refrigerant, and as the deadline draws closer toxicity issues are raised with proposed blends.
R134a Refrigerant Automotive Air-Conditioned HoseJ2064_200512 (Historical)12/12/2005
This SAE Standard covers hose and hose assemblies intended for conducting liquid and gaseous R134a refrigerant in automotive air-conditioning systems. The hose shall be designed to minimize permeation of R134a refrigerant, contamination of the system, and to be functional over a temperature range of -30 to 125øC. Specific construction details are to be agreed upon between user and supplier. A hose marked "J2064" signifies that it has been coupled, tested, and has met the requirements of SAE J2064. It is the hose assembly manufacturer's responsibility to see that the assemblies meet the specified acceptance criteria for this specification.
Interior Climate Control Steering Committee
Thermophysical Properties of the Natural Environment, Gases, Liquids, and SolidsAIR1168/9 (Historical)6/22/2004
This AIR is arranged in the following four sections: 2A - Properties of the Natural Environment 2B - Properties of Gases 2C - Properties of Liquids 2D - Properties of Solids A summary of each section is given below. Section 2A - This section includes currently applicable earth atmosphere standards (Refs. 101 and 103) and data on the near-Earth environment. Limited data on Mars and Venus reflected solar and planetary-emitted radiation and on micrometeorite data are also included. For space vehicle applications, environmental models are of two general types: orbital and reentry. For orbital models, variable properties such as time and solar flux are usually averaged. Reentry atmospheres are chiefly a function of location and altitude, and selection may be based on reentry location. Variation with latitude is an important local effect (Ref. 106). The electromagnetic solar radiation data in this section are for altitudes above the Earth’s atmosphere. The amount of radiation energy below 0.22μ (Fig. 2A-10) is small and has little effect on vehicle thermal balance. It is primarily of interest because of degradation effects on thermal control coatings. Planetary albedo (fraction of solar radiation which is reflected) varies strongly with the local solar angle of incidence, surface characteristics, and existence of planetary atmosphere (particularly the extent of cloud cover; see Ref. 121). The following ranges may be used as a guide: (1) Earth, 0.33-0.39 (frequently considered as uniform diffuse radiation, average value in low orbits is 0.36). (2) Venus, 0.55-0.90 (0.76 at 5500Ǻ). (3) Mars, 0.3 at 7000Ǻ; 0.04 below 4500Ǻ. Planetary thermal emission is predominantly infrared. Emission from the atmosphere occurs only at wavelengths at which the atmosphere absorbs; for wavelengths where the atmospheric gas is transparent, the emission comes from the planetary surface. An average value of 15% of solar flux is frequently used for low Earth orbits. The opaque atmosphere of Venus prevents long wave surface radiation from emerging. Thermal emission in the 8-13μ range comes from the upper atmosphere, which has an emitting temperature of 230K. The mean Mars surface temperature range is 200-300K, and these values bracket the seasonal, diurnal, and latitudinal variations (Ref. 118). Considerable uncertainty still exists on meteorite data (Refs. 111-113). Ref. 114 is a more recent attempt to provide an interim standard. Data on space environments can be used only as a guide, since they are subject to rapid obsolescence as additional information from interplanetary probe experiments becomes available. Sections 2B, 2C, and 2D - The data in these sections are presented primarily in graphical form. The data were compiled by Professor Harold Sogin, circa 1966, and represent a selection of the then best currently available sources. The following properties are listed as applicable to the materials listed alphabetically in the index, Par. 7. Consult specific material for desired properties. Materials are indexed by figure number and table number. Section 2E - Thermodynamic Characteristics of Working Fluids and Section 2F - Properties of Heat Transfer Fluids are in AIR 1168/10.
AC-9 Aircraft Environmental Systems Committee
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