Vehicle Air Conditioning System Research Articles

Global selection appraisal study for heat pump system of electric vehicle based on energetic, economic, and environmental analysis

The development of electric vehicles (EVs) exhibits rapid and remarkable progress nowadays, serving as a crucial route to accomplish the target of mitigating greenhouse gas emissions. As an integral part of the thermal management system oriented toward electric vehicles, the heat pump air conditioning system for electric vehicles is the result of a comprehensive choice that trades off the cooling and heating performance, environmental performance and economic cost. Particularly, different regions around the world suffer varying cooling and heating challenges due to the complicated climatic characteristics. Thus the most suitable refrigerant and system cycle structure may differ. This paper focuses on evaluating both the refrigerants and cycle structures to screen the most suitable choice. According to the climate conditions of different cities, the annual energy consumption, life cycle climate performance, and economic cost of the basic system (Base), two-stage compression system (TSC,IC), and vapor injection (VI) system with CO2, R134a, and R1234yf refrigerants respectively, are quantitatively analyzed and evaluated. Subsequently, through comparative analysis, a comprehensive selection map for heat pump systems in electric vehicles worldwide is developed and the most suitable heat pump air conditioning system for each cites is determined. The results can provide a selection reference and decision-making for the air conditioning system of electric vehicles from regional considerations. It was found that the CO2 HPACVI was recommended for cold regions to meet both environmental and economic requirements. In warm region, the R1234yf HPACBase system was recommended to be used. For regions transitioning from cold to warm climates, the R1234yf HPACVI system was suggested. In hot region, the R1234yf AC system was recommended.

Diagnostic Insights for Optimal Avanza/Xenia AC Performance

This study investigates the AC system of Avanza/Xenia vehicles through diagnostic procedures aimed at identifying potential issues and ensuring adherence to maintenance standards. The air conditioning (AC) system in vehicles plays a pivotal role in ensuring driver and passenger comfort, necessitating regular monitoring and maintenance. Utilizing measuring tools such as compressors and multimeters, the main components including the magnetic clutch and evaporator were assessed. Results indicate that measured values, including magnetic clutch coil resistance (3.9 ohms), magnetic clutch gap (0.5 mm), and blower system resistance (ranging from 0 to 2.6 ohms), fall within acceptable service limits outlined in the Avanza/Xenia manual. Consequently, no repair procedures were deemed necessary, affirming the normal condition and suitability for use of the AC system. This research fills a knowledge gap by providing a systematic diagnostic approach for evaluating vehicle AC systems, offering implications for maintenance practices in ensuring optimal performance and longevity. Highlights: Routine maintenance prolongs AC system lifespan. Accurate diagnosis prevents potential issues. Component inspection ensures system health. Keywords: PMCB, Vehicle Air Conditioning System, Maintenance, Repair, Troubleshooting

Intelligent control of electric vehicle air conditioning system based on deep reinforcement learning

The existing AC system of EVs consumes a lot of energy in summer, resulting in reduced range. Additionally, the cabin temperature (Tcabin) fluctuates due to varying driving conditions. In this paper, an innovative cooling strategy is designed to address the above drawbacks using deep reinforcement learning algorithms. The primary objective of this strategy is to achieve high-precision temperature control while concurrently minimizing the energy consumption of the AC system. The strategy combines compressor speed (Ncompressor) and blower airflow (Bairflow) control to optimize the AC system's performance. The RL controller minimizes energy consumption by reducing Ncompressor while increasing Bairflow, thus ensuring a constant cooling capacity (Q). And it effectively reduces temperature fluctuations within the cabin. Finally, the RL control strategy was compared with on/off control and proportional integral differential (PID) control. The results showed that RL control performed well in the multi-objective optimization of the AC system. In terms of temperature control, it effectively reduces the amount of overshooting, and the minimum temperature fluctuation achieved through RL control is merely 0.07 °C, exhibiting an 84.4 % and 86.5 % decrease compared to traditional control methods. The average absolute temperature error stands at 0.06–0.07℃, maintaining a remarkable precision in preserving the target temperature. Furthermore, RL control not only ensures superior energy efficiency but also reduces energy consumption by up to 5.98 % and 7.65 % compared with traditional control methods.

Research on Energy Consumption Model of Heat Pump Air Conditioning System for New Energy Vehicles Based on Digital Technology

Energy shortages and environmental degradation are issues that are getting more and more significant globally. New energy vehicles are being promoted by the state due to the advantages of low pollution and low fuel consumption. However, due to battery technology, the range of new energy vehicles cannot meet the needs of users. As the most energy-efficient auxiliary device, the energy consumption of air conditioning will significantly reduce the range of new energy vehicles. In low temperature environments, heating energy consumption will reduce the range of vehicles by more than 50%. Therefore, the research aims to reduce the energy consumption of air conditioning systems in new energy vehicles by reducing load demand and improving operating efficiency. The study designs a low-temperature heat pump air conditioning system based on digital technology and then uses a computational algorithm to construct an energy consumption model for the heat pump air conditioning system of a new energy vehicle. According to the test results, the system’s average increase in heat production after activating the enthalpy charge is 35% and its average COP is 0.14% lower than when switched off. At -5oC, the air outlet temperature of the system reaches up to 50.0oC. Summer cooling energy consumption increases exponentially with temperature, while winter heating energy consumption decreases linearly with temperature. In addition, the range decreases significantly as the ambient temperature deviates from the human comfort zone. The decline in the winter range is more severe than that in summer, moreover, the range of modern energy vehicles is reduced by 30% at an average winter temperature of -10oC. In summary, the low-temperature heat pump system offers greater performance. It is more useful in real-world applications and can offer a rational alternative to air conditioning’s energy-saving tactics.

Plasma disinfection procedures for surfaces in emergency service vehicles: a field trial at the German Red Cross

The demand for thorough disinfection within ambulances is essential, given the in-vehicle medical procedures and the potential high risk of infections due to patients' open wounds. One solution that can address this hygiene challenge involves the application of reactive products generated from atmospheric (air) oxygen and water vapor, activated through the use of cold plasma. Cold plasma's charged particles perforate the cell membranes of microorganisms. This process does not work in human cells, as proteins in the form of enzymes within the body break down the cold plasma and protect the cells. The study was done on an ambulance that was contaminated in eight places. Samples were taken from each site, and two surfaces measuring approximately 8 × 8 cm were carefully sealed and marked. These surfaces were deliberately contaminated by applying an Enterococcus faecium suspension of 8.5 × 107 CFU/mL using a sterile cotton swab. It was followed by the disinfection procedure, that was initiated with the PLASMOCAR device. It was positioned on the front workspace and operated for a duration of 30 min, utilizing the vehicle's onboard voltage. Throughout the operation, all doors and windows were closed and the vehicle's air conditioning system remained active. After the completion of the disinfection process, samples were collected from the surfaces for bacterial counts. A reduction of 3.73 log levels in initial bacteria was accomplished within the rescue vehicle for Enterococcus faecium, equivalent to a 10–fourfold reduction in bacteria, eliminating up to 99.99% of the initial microorganisms. This success makes the process well-suited and convenient as an ongoing "background" procedure to enhance the established disinfection procedures. The established disinfection procedures outlined in the hygiene plan must be promptly implemented whenever mechanical surface cleaning is required. The use of PLASMOCAR offers an extra layer of protection and security, significantly decreasing the risk of microorganism transmission through cross-contamination and aerosols. This is a significant benefit for the well-being of both staff and patients.

Energy-saving Optimization of Frequency-variable Heat Pump Air Conditioning System for Electric Vehicles Based on a Genetic Algorithm

Energy-saving Optimization of Frequency-variable Heat Pump Air Conditioning System for Electric Vehicles Based on a Genetic Algorithm

Experimental assessment of lamella heat exchanger as cold intake air system for spark ignition engine by utilizing vehicle air conditioning system

Global warming and air pollution have become major concerns for humanity, especially in the last few decades. The transport sector contributes significantly to a large proportion of urban air pollution due to the dramatic increase in vehicle production and transportation growth, resulting in harmful emissions. Cooling the intake air temperature is one of the alternative strategies to reduce exhaust emissions and improve combustion conditions. The present study adopted the Lamella heat exchanger (LHE) as an intake air cooling device for a 1.5 L naturally aspirated engine. The design size of LHE is based on the maximum space available in the test vehicle for its installation. A refrigerant derived from the vehicle air conditioning (VAC) system acts as a coolant medium for LHE. For experimental testing, two types of vehicle statuses are considered, i.e., moving and static, to evaluate the performance of the cooling device in both positions. Engine power, torque, exhaust emissions, and fuel consumption are designated as evaluating parameters. The results depict that lowering the temperature of the intake air by 30–40°C through LHE reduces the increased quantity of exhaust emissions due to the VAC system by 43.6%, 39.5%, 47.3%, and 64.5% for CO, CO2, HC, and NOx respectively. Further, the amount of lost engine power and torque due to the VAC system is partially recovered by 17% and 24%, respectively, by introducing cold air into the engine. Convincingly, LHE has a significant potential to improve engine performance.

Enhancement of electric vehicle air-conditioning system with dual condensers

Air-conditioning systems of electric vehicles (EV) not only cool the cabin space but also remove the heat generated by the battery during rapid charging or driving. These two cooling functions consume electric energy, affecting electric vehicle competitiveness in fuel efficiency and mileage. Therefore, improving the system performance and efficiency of EV air-conditioning systems is essential. Previous studies have mainly focused on improving the system performance and efficiency by optimizing the main design parameters of the air-cooled condenser or by comparing the performance and efficiency of water- or air-cooled condensers. This study proposed a novel architecture, and conducted experimental and numerical research on the effects of combined condensers that use both water and air to condense refrigerant on the performance and efficiency of the EV air-conditioning system. The simulation results of the developed numerical model were compared with the bench test results. The compressor power consumption and system efficiency under the maximum capacity conditions were selected for comparison. The results show that the air-conditioning system with the combined condenser reduced the compressor power consumption by 13.1% to 14% and improved the system efficiency by 14.6% to 15.7% compared with the air-conditioning system using a single air-cooled condenser.

Energy and Exergy Analysis of an Automobile Hybrid Ejector Refrigeration System Utilizing Its Exhaust Waste Heat

Abstract A major current focus of refrigeration and air-conditioning research is energy usage and environmental impact (e.g., the influence of refrigerants and air-conditioning systems on ozone layer depletion and global warming). The ejector-based refrigeration system is a technology that, it is hoped, can save power while using environment-friendly refrigerants to reduce any adverse effects on nature. The reduction of compressor dependency is the first and essential aim of this study; the second is to demonstrate the replacement of R134a with the new refrigerant R1234yf in motor vehicle air-conditioning systems, establishing the benefits of employing R1234yf in conjunction with a hybrid air-conditioning system. In such a system, the engine's exhaust gases are used to operate the ejector. A numerical model has been developed which estimates the ejector entrainment ratio at a specified spindle and primary nozzle exit position. A theoretical model using energy and exergy analysis illustrates the impact of hybrid systems on performance under different operating conditions (i.e., engine exhaust, ambient air, and evaporator temperatures). At a specified exhaust temperature, a detailed comparison has been conducted between a current air-conditioning system with R134a and the hybrid system with R1234yf. It was found that the R1234yf hybrid system reduced compressor energy consumption by 44.43% and operating exhaust heat levels by 12.79%. The coefficient of performance increased by 41.42%, while the exergetic efficiency reduced from 37.14% to 13.85%. Cooling capacity dropped by 12.73%. The hybrid air-conditioning system based on R1234yf demonstrated tremendous potential for improving vehicle air-conditioning system efficiency.

Review of Thermal Management Technology for Electric Vehicles

The burgeoning electric vehicle industry has become a crucial player in tackling environmental pollution and addressing oil scarcity. As these vehicles continue to advance, effective thermal management systems are essential to ensure battery safety, optimize energy utilization, and prolong vehicle lifespan. This paper presents an exhaustive review of diverse thermal management approaches at both the component and system levels, focusing on electric vehicle air conditioning systems, battery thermal management systems, and motor thermal management systems. In each subsystem, an advanced heat transfer process with phase change is recommended to dissipate the heat or directly cool the target. Moreover, the review suggested that a comprehensive integration of AC systems, battery thermal management systems, and motor thermal management systems is inevitable and is expected to maximize energy utilization efficiency. The challenges and limitations of existing thermal management systems, including system integration, control algorithms, performance balance, and cost estimation, are discussed, along with potential avenues for future research. This paper is expected to serve as a valuable reference for forthcoming research.

Performance investigation of new design thermoelectric air conditioning system for electric vehicles

Conventional automobile air conditioning systems use environmentally harmful Chlorofluorocarbons. This method also makes noise and uses a lot of battery energy, making it unsuitable for electric vehicles. So in this paper, the performance of a newly designed cooling system based on the thermo-electric cooling technique installed on the vehicle's roof is proposed and investigated. A complete theoretical transient thermal model based on energy balances is constructed, solved, and validated. The results show an optimum value of the used number of thermoelectric modules, which depends on the input power. This value is 150 for an input power of 200 W and 100 for an input power of 1000 W. At an ambient temperature of 42 °C and without applying a cooling system, moving vehicle with three persons and closed windows, its cabin temperature reaches about 66 °C; in contrast, after applying the TEC system, this temperature reaches around 26 °C at input power 1000 W. The coefficient of performance of the system reduces from about 3 to about 0.85 by increasing the input power from 200 to 1000 W, respectively. Although the coefficient of performance of this system is lower than that of the conventional, it has advantages that make it competitive with conventional air conditioning systems. An economic study based on the Egyptian market shows that the annual cost of the thermo-electric cooling system is lower than that of the conventional one.

Exergy Analyses of Vehicles Air Conditioning Systems for Different Refrigerants

There are a limited number of studies in the literature that include detailed exergy analysis of vehicle air conditioning systems. In this study, in order to increase the performance of the air conditioning system in vehicles, a detailed exergy analysis has been made with the assumption that different refrigerants are used. R-134A, R-E245cb2, R-404A, R-1234ze(Z), R-161, R-1234zd(E), R-513A, R-1234ze(E) and R-1234yf has been chosen as the refrigerant. In the analysis, a comparison has been made by considering the environment, performance and safety values. While the COP values of the cycles increase with increasing evaporator temperatures, the COP values decrease at increasing condenser temperatures. On the other hand, exergy efficiency decreases with increasing evaporator and condenser temperatures. Also it is aimed to evaluate all the elements of a vehicle air conditioning system with exergy analysis.

Experimental Research on the Effect of Oil Charge Ratio on the Cooling Performance of CO2 Air Conditioning System for Electric Vehicles

From the perspective of the engineering application, the influence of the oil charge ratio on the cooling performance of the electric vehicle CO2 air conditioning system is experimentally studied in this paper. An online test device for oil circulation rate is set up on the built CO2 air conditioning system test bench. The experiment is conducted under different ambient temperatures and compressor speeds in the fresh air mode. As the oil charge ratio increases, the oil circulation rate increases as well as the oil mass flow rate, while the refrigerant mass flow rate decreases slightly. Under the refrigerant charge amount of 550 g and ambient temperature of 35 °C and 40 °C, this system reaches its best cooling performance when the oil charge ratio is in the range of 20% and 25%. And the maximum COPs are 2.46 and 2.36, respectively. The increase in the oil charge ratio is beneficial to the improvement of the isentropic efficiency and the volumetric efficiency of the compressor. The change in oil circulation rate has less effect on the pressure drop in the gas cooler than that in the evaporator.

On the Usefulness of Employing ANSYS Motor-CAD Software in Designing Permanent Magnet Synchronous Machines

This paper deals with the simulation of a permanent magnet synchronous machine (PMSM) to be developed for driving a scroll compressor of a vehicle air conditioning system. The simulations were needed for the verification of the pre-sizing and for the electromagnetic behavior analysis of the PMSM. These were performed by using the ANSYS Motor-CAD software. All the obtained results emphasized that the pre-sizing of the PMSM was performed correctly, and the designed electrical machine can fulfill all the prescribed requirements. To highlight the superiority of the chosen surface-mounted PMSM topology, a comparative study was performed for four PMSMs having the same stator but different rotor topologies having the same quantity of permanent magnets. The study revealed that the PMSM with permanent magnets on its rotor surface is the best-fitting variant for the foreseen application. By intensively using the ANSYS Motor-CAD software, the authors appreciated that this product is a very useful tool in the hands of the designers not only in evaluating the machine’s computed geometry (by checking its correctness and feasibility), but also in its in-depth electromagnetic analysis and in calculating its parameters of interest.

Real-time energy performance benchmarking of electric vehicle air conditioning systems using adaptive neural network and Gaussian process regression

One major concern of the electric vehicle is the limited driving range per charge. Among its auxiliary systems, the heating, ventilation, and air conditioning (HVAC) system consumes the largest amount of electricity and can have a significant impact on the driving range when operational faults occur. This paper proposes a real-time benchmarking method to continuously evaluate the energy performance of a large number of electric vehicle air conditioning systems. Each system is benchmarked based on the energy consumption of its peer systems. Considering the energy consumption is influenced by several impact factors including the ambient environment and the cooling capacity, this study encodes the impact factors with an Autoencoder to measure the similarities between operating conditions. Also, considering the difference in operating conditions between a system and its peers, the uncertainties in energy performance benchmarks of the peer systems are quantified by the Gaussian process given its probabilistic nature. For each peer system, a Gaussian process regression model is developed as a benchmark, and the performance of the target system is assessed by comparing its measured energy consumption with the averaged benchmarks of all its comparable peers, accounting for the uncertainties. With the continual learning algorithm adopted, the Autoencoder can be updated periodically to adapt to real-time operational data with minimal computational cost. The real-time benchmarking method is applied to electric bus air conditioners in Haikou and Sanya, China, and can effectively identify malfunctioning systems. This method can be conveniently deployed on cloud for smart health management of public electric vehicles in smart cities.

Heating performance of heat pump air conditioning system for battery electric vehicle with different refrigerants

To improve the heating performance of Heat Pump Air Conditioning System (HPACS) of Battery Electric Vehicle (BEV) and reduce the greenhouse effect of refrigerants, the performances of multiple refrigerants in different modes and conditions are analyzed in this paper. Based on Worldwide Harmonized Light Vehicles Test Cycle (WLTC) dynamic conditions, the impact of heating on battery State of Charge (SOC) is analyzed in HPACS and Positive Temperature Coefficient (PTC) combined heating mode. To better evaluate the contribution of refrigerants to the greenhouse effect, Total Equivalent Warming Impact (TEWI) is used to evaluate multiple refrigerants. The results show that heating capacity increases with the increment of compressor power and air velocity. As compressor power decreases and air velocity increases, COP increases. R32 and R744 are the optimal refrigerants. When the ambient temperature is between −10°C and −15°C under WLTC conditions, the SOC reduction of R32 system is 20.8%–21.1% less than that of R134a system. When the ambient temperature is between −20 and −25°C, the SOC reduction of R744 system is 21.4%–21.6% less than that of R134a system. And the carbon dioxide emissions of R32 and R744 systems are 35.1%, 66.9%, 39.2%, and 55.5% less than that of R134a system, respectively.

An experimental method for evaluating vehicle cabin airtightness and ventilation performance

An experimental method is proposed for evaluating the airtightness of a vehicle cabin and the ventilation effects of three components of the vehicle ventilation system. The measurement results are used to derive a theoretical equation to predict the total air infiltration rate of the cabin as a function of the pressure difference between the cabin interior and exterior, respectively. The validity of the predictive equation is demonstrated by means of fan pressurization experiments performed with the vehicle air-conditioning system set in the fresh air mode. It is shown that the prediction results for the total ventilation rate deviate from the experimental results by less than 10%. The infiltration ventilation effect of natural diffusion in the vehicle cabin is measured using the CO2 tracer gas method. The air exchange rate (ACH) of the cabin is found to be 0.816 in the recirculation air mode and 3.554 in the fresh air mode.

Performance analysis and operation strategy of a dual-evaporation temperature heat pump system for electric vehicles in winter

With increasingly serious environmental and energy issues, efficient and environmentally friendly electric vehicles have received more attention. However, the high heating and dehumidification energy consumption of their air conditioning system reduces their driving range in winter, giving passengers and drivers range anxiety. In this study, a dual-evaporation temperature heat pump system is proposed to reduce the energy consumption of electric vehicle air conditioning systems in winter, and a simulation model of the proposed system is developed. First, the volume ratio of the dual-cylinder compressor is optimized. Subsequently, the performance of the proposed system in various operation modes under different ambient conditions is compared. The results indicate an optimized volume ratio of 2.85, which is taken as the system’s design condition. The dual-evaporation temperature heating dehumidification mode shows superior performance compared with the conventional mode under typical winter conditions in three different climatic zones. Moreover, energy consumption can be reduced by reasonably controlling the operation mode based on ambient conditions. An operation strategy for the dual-evaporation temperature heat pump system in winter is proposed through the regional division of the psychrometric chart, and the energy-saving operation mode of the system is analyzed for different climate zones in China.

Electric Vehicle Air Conditioning System and Its Optimization for Extended Range—A Review

Environmental protection initiatives are speeding up the replacement of the present IC engine-based transportation system with an electric motor-driven system. In electric vehicles (EV), energy stored in batteries is used for the traction of the vehicle and the operation of the auxiliaries. The range of the electric vehicle was identified to be one of the major challenges faced by the EV segment. The optimization of the consumption of stored energy is the best solution for range improvement in an EV. Auxiliaries in the vehicle include basic accessories such as a lighting system and equipment for improved comfort such as air conditioners. Air conditioning equipment is the major power-consuming auxiliary in an EV apart from the traction motor. This review article discusses the significance and influence of different components of the air conditioning system, and methods followed by researchers to optimize the performance and reduce the energy consumption of the air conditioning system to extend the range of vehicles. The effects of thermal load and volume of space to be conditioned were also considered in this study. This review concludes by stating the different possibilities for the reduction in power consumption and emphasizes zonal air conditioning of occupant space as a solution for reducing energy consumption or increasing the range of EVs. Compared to full-space air conditioning, zonal AC can reduce power consumption by up to 51%.

Simulation of CO2 heat pump air conditioning system for new energy vehicle

The CO2 heat pump air conditioning system of new energy vehicle is designed, and the vehicle model of CO2 heat pump module and heat management system is established based on KULI simulation. The effects of refrigerant charge, running time and compressor speed on the heat pump air conditioning system is studied, and the energy consumption is compared with the PTC heating system and the CO2 heat pump air conditioning system without waste heat recovery. The results show that the optimal charge for full-service operation is 750 g; increasing the compressor speed can increase the cooling capacity, so that the refrigerant temperature in the passenger compartment and battery inlet can quickly reach the appropriate temperature, but the COPh, COPc are reduced by 2.5% and 1.8% respectively. By comparing it with PTC heating and CO2 heat pump air conditioning systems without waste heat recovery, it is found that the energy consumption of this system is only for the PTC heating systems 42.5%, without waste heat recovery carbon dioxide heat pump air conditioning system of 86.6%. It greatly saves energy, but also increased the waste heat recovery function, so that the system supply air temperature increased by 26%, improve passenger cabin comfort. This provides a reference for the future experimental research of CO2 heat pump air conditioning and heat management system.