Vehicle Air Conditioning System Research Articles

Quantitative assessment of refrigerant impact on vehicle air-conditioning systems via Z-Freq 2D statistical analysis

In this study, the impact of refrigerant types on the performance and efficiency of vehicle air-conditioning (AC) systems was quantitatively assessed using a novel two-dimensional Z-Freq 2D statistical analysis method. Wireless vibration accelerometers, capturing both horizontal and vertical vibrations, were utilized to measure the dynamic response of the air-conditioning compressor. Before data collection, meticulous calibration of sensors was conducted to ensure the accuracy and reliability of measurements. The introduction of the Z-Freq 2D statistical analysis technique, developed specifically for this research, allowed for a comprehensive examination of the vibrational data, facilitating a deeper understanding of the effects of different refrigerants on AC system performance. To validate the effectiveness and reliability of the Z-Freq 2D analysis, machine learning techniques were employed. These techniques provided a robust framework for the analysis of the statistical data, with performance evaluation indicators demonstrating the efficacy of the newly developed method. The experimental setup was based on an actual vehicle air-conditioning test rig, designed to simulate real-world operating conditions accurately. The findings of this research offer significant insights into the selection of refrigerants for vehicle AC systems, highlighting the potential for enhanced system performance and efficiency through the application of advanced statistical analysis and machine learning validation techniques. This study not only contributes to the field of automotive thermal management but also paves the way for future research in the optimization of vehicle AC systems.

Research on intelligent control of fresh air introduction based on electric vehicle air conditioning system

The high power consumption of air conditioning systems is an important reason for the significant reduction in EVs (electric vehicles) range. Reducing its energy consumption has become an urgent industry problem to be solved. In order to reduce the energy consumption of the air conditioning system, this paper proposes an intelligent control strategy for the proportion of fresh air in the cabin of EVs, taking into account the impact of factors such as the number of passengers in the cabin, ambient temperature, and humidity on demand for fresh air, and analyzes the energy-saving effect of the intelligent control strategy through simulation. The analysis found that the minimum fresh air demand in the passenger compartment is greatly affected by the number of passengers in the cabin. The developed intelligent control strategy can significantly reduce the energy consumption of air conditioning systems. The energy-saving effect in northern China is significantly better than in southern China. The actual driving range of refrigeration and heating modes can be improved by 50 and 126 km, respectively.

Simulation of diffusion of combustible refrigerants R1234yf and R290 leakage in automotive air conditioning

Electric vehicles that utilize a heat pump system have a refrigerant charge increase of at least 400 g compared to traditional fuel vehicle air conditioning systems. If combustible refrigerants are used, the risk of combustion increases when the refrigerant leaks and spreads to the passenger compartment. This paper dynamically monitored the volume concentrations of combustible refrigerants R1234yf and R290 as they leaked and entered the passenger compartment accompanied by air supply by numerical simulation. The results indicated that refrigerants are more prone to accumulate in the rear row than in the front. After a leak, the average volume concentration of R1234yf at the four air outlets was 1.58 %, and 3.36 % for R290. at the breathing points of four passengers, the average volume concentration was 0.99 % for R1234yf and 2.39 % for R290. Near the feet of the passengers, the average volume concentration was 0.95 % for R1234yf and 2.27 % for R290. The highest volume concentration of R1234yf in the passenger compartment was below its LFL, whereas all monitoring points for R290 exceeded its LFL. Compared to experimental data, the difference in maximum refrigerant volume concentration was approximately 1.2 %.

Transmission Loss Characteristics of Dual Cavity Impedance Composite Mufflers for Non-Planar Wave Cavity Resonance

In conventional gasoline automobiles, the engine powers the air conditioning system and engine noise can somewhat mask the noise and vibration of the air conditioning system. In pure electric vehicles, however, the absence of an engine makes the air conditioning system’s noise more noticeable, concentrated in a limited frequency range at constant speeds. As a result, aerodynamic noise from the air conditioning system is a primary noise source in electric vehicles. Pipeline silencers are the main method for reducing this noise. The current silencer design uses plane wave acoustic theory but when cavity modal resonance occurs, the transmission loss error is relatively high. This article addresses the issue of non-planar wave cavity resonance, studying the cavity modal of a muffler using the finite element method to reveal the transmission loss under cavity mode resonance. A dual cavity expansion structure of an impedance composite muffler is proposed, with sound-absorbing materials placed in the cavity to enhance acoustic performance. The analysis of the transmission loss characteristics of the impedance composite muffler provides a theoretical basis for noise control in pure electric vehicle air conditioning systems.

Study of Low-Temperature Energy Consumption Optimization of Battery Electric Vehicle Air Conditioning Systems Considering Blower Efficiency

Battery electric vehicle (BEV) air conditioning systems often use positive temperature coefficient (PTC) heaters to heat the passenger compartment. The heating process consumes a lot of energy in low-temperature environments, which seriously affects the driving range and user experience. This study aims to reduce the low-temperature energy consumption of the air conditioning system and improve energy efficiency through an innovative optimization method. In this study, the energy consumption composition of the air conditioning system was analyzed, and the goal of minimizing the sum of the total power consumption of the PTC heater and the blower was determined, while the efficiency characteristic of the blower was considered at the same time. The relationship between the average temperature of the passenger compartment measurement points and the PTC power and airflow rate was studied by combining experiments and numerical simulations, and the alternative operating conditions that met the temperature requirement were determined. On this basis, the total power consumption of the air conditioning system was analyzed and optimized. The results show that PTC power, airflow rate, and blower efficiency all have an important influence on the total power consumption of the air conditioning system. The optimized scheme could reduce the theoretical total power from 1315.32 W of the original scheme to 1246.83 W, and the actual total power from 1350.05 W of the original scheme to 1326.56 W, with reductions of 5.21% and 1.74%, respectively. The low-temperature energy consumption optimization method for the BEV air conditioning systems proposed in this study is instructive for the selection of blowers and the design of control strategies for air conditioning systems.

Fuzzy-based thermal management control analysis of vehicle air conditioning system

Automotive air conditioning (ACC) system designers faced unique challenges in satisfying customer demands for efficient and comfortable operation across a broad temperature range. The AAC system's effective or fixed temperature setting makes this possible. Many climate control models, like the state flow switching controller in MATLAB control, must handle heating and cooling due to a single Simulink/environment software and frequently contain steady-state error (SSE). The present research proposes to design an automatic temperature control scheme and fuzzy logic control (FLC) for an automotive air-conditioned (AAC) system. In addition, it employs MATLAB Simulink/environment software to model the fuzzy control technique to analyze the AAC system's response. A simulation has been set up to evaluate the suggested system performance to match a selection of user-specified reference temperatures and compressor speeds. Compared with a PID-controlled AAC system, the proposed FLC-based system reduced the undershoot to only 2.30% from 33.30% respectively, and was robust, quicker, and better at controlling temperature.

Application of Refrigerant Cooling in a Battery Thermal Management System under High Temperature Conditions: A Review.

Battery thermal management (BTM) is crucial for the lifespan and safety of batteries. Refrigerant cooling is a novel cooling technique that is being used gradually. As the core fluid of refrigerant cooling, refrigerants need to possess excellent properties while meeting environmental requirements. This paper elucidates the current state of refrigerants (single refrigerants and mixed refrigerants), synchronously summarizing them from the perspectives of refrigerant properties and refrigerant cooling (immersion and cold plate indirect). It outlines the advantages and disadvantages of single and mixed refrigerants as well as the research and development in the vehicle thermal management system (TMS). The choice of refrigerant directly affects cooling performance, and research on vehicle air conditioning (AC) systems can indirectly guide the BTM. R1234yf and R152a can directly replace R134a, while although R744 has a strong heating capacity, it cannot directly replace R134a. Specific mixed refrigerants reduce the global warming potential (GWP) and flammability issues, thereby improving system efficiency. Additionally, immersion cooling controls the temperature through container pressure. Coordinated control strategies are crucial for indirect cold plate cooling, offering broad prospects for optimizing the cold plate design and intelligent control. The selection of refrigerant and the optimal design of the cooling method greatly improve the thermal performance of the battery. This may promote the good development of BTM.

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.

Performance of adjustable multilayer film based on radiation cooling and electrochromism

Energy and environmental challenges caused by the excessive consumption of fossil fuels are major concerns worldwide, and the use of automotive air conditioning can increase total fuel consumption by 10% to 30%, thereby exacerbating these problems. To reduce the energy consumption for automotive air conditioning, a multilayer-film design based on radiative cooling and electrochromic modulation is proposed for regulating the temperature inside vehicles. The designed multilayer-film not only passively realizes temperature drop but also actively regulates the entry of solar radiation, which can help the vehicle air conditioning system to adjust the interior temperature autonomously. To verify its effectiveness, a film-applied empty box device is designed for radiometric temperature measurement. Experimental results indicate that the maximum interior temperature drop of the multilayer film increases by approximately 9.8 ℃ compared with that of single-layer films in the sunlight irradiation, and dynamic temperature regulation of about 4.6 ℃ can be achieved by adjusting the transmittance of the multilayer film. To study the environmental adaptability of the multilayer film, experiments are conducted on an outdoor film-applied device during the summer and winter in Shenyang, China (<inline-formula><tex-math id="Z-20241025175516">\begin{document}$\rm 41^\circ44'N, 123^\circ39'E$\end{document}</tex-math></inline-formula>), the place which is characterized by a typical temperate continental climate. Results indicate that under high temperature conditions of 30–40 ℃ in summer, the maximum internal temperature drop of the multilayer film reaches 12.9 ℃; while under low temperature conditions of 0–15 ℃ in autumn and winter, the maximum internal temperature drop is only 1.9 ℃, preventing the interior temperature from being too low. In addition, the maximum interior temperature drop increases with the solar radiation intensity and ambient temperature increasing. Therefore, the proposed multilayer-film design, with its potential for temperature self-regulation, provides a promising solution for reducing energy consumption and improving passenger comfort.

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.