Automotive Air Conditioning Research Articles

Performance analysis of automotive air conditioning systems with electric compressors using R1234yf refrigerant: Insights into power consumption, cooling capacity, and energy efficiency

R1234yf, a low global warming potential (GWP) refrigerant, offers a promising alternative to traditional refrigerants like R134a. This study analyzes automotive air conditioning systems (AAC) equipped with electric compressors and utilizing R1234yf refrigerant. The interrelationships between refrigerant charge, compressor speed, power consumption, cooling capacity, and energy efficiency are examined. The results show that increasing refrigerant charge and compressor speed leads to higher power consumption due to increased compressor work. However, higher refrigerant charges and compressor speeds improve cooling capacity in line with heat transfer principles. As refrigerant charge and compressor speed increase, the energy efficiency, measured by the Coefficient of Performance (COP), tends to decrease, indicating a trade-off between cooling capacity and energy efficiency. Optimizing refrigerant charge and compressor speed is crucial to strike a balance between cooling performance and energy efficiency. R134a outperforms R1234yf, with an average percent difference in COP approximately 25% higher at all compressor speeds. This study contributes to the understanding of AAC system performance and guides the development of energy-efficient automotive air conditioning. Future research can further explore system components and conditions to enhance energy efficiency and advance air conditioning technology.

Energetic performance and life cycle carbon emission of CO2 automotive air conditioning system with an evaporative gas cooler and a dual-evaporator configuration in China

Enhanced actions on climate change have led CO2 air conditioner to take center stage in automotive field. However, its inefficient performance in hot climates limits its further application. A dual-evaporator (D-E) configuration, an evaporative gas cooler (EGC), and their combination (D-E + EGC) were first integrated with the system and experimentally studied in this paper in an attempt to alleviate this problem. Annual energy consumption and life cycle climate performance (LCCP) under four modes (baseline, D-E, EGC, and D-E + EGC) in China were estimated. Results show D-E increases evaporation pressure and EGC is able to decrease discharge pressure. D-E + EGC combines the advantages of both. Thus, improvement percentage in coefficient of performance (COP) brought by D-E + EGC is the highest, followed by those of EGC and D-E. This percentage is more significant at higher ambient temperatures, and even reaches 67.4 % at 45°C outdoor condition. In any mode, annual energy consumption and LCCP in southeast China are double or triple of those in other regions, which shows this system is of high energy consumption and high emission in southeast China. Compared with baseline mode, annual energy consumption and LCCP can be reduced by 3 ∼ 7 % for D-E, 14 ∼ 16 % for EGC, and 18 ∼ 22 % for D-E + EGC. Specifically, D-E + EGC could save up to 890 kWh of electricity and reduce carbon emission by up to 440kgCO2 per vehicle, indicating this technique is a promising way to reduce energy consumption and carbon emission for vehicles equipped with CO2 air conditioners.

Tribology Performance of TiO2-SiO2/PVE Nanolubricant at Various Binary Ratios for the Automotive Air-conditioning System

Tribological properties are crucial for air-conditioning system performance. The properties can be improved using nanolubricant. However, the effect of the binary ratio of hybrid nanolubricants on the tribological performance of automotive systems is limited in the literature. Therefore, the present study investigates the tribology performance of TiO2-SiO2 nanolubricants for application in automotive air-conditioning (AAC) systems. The dispersion of TiO2 and SiO2 into PVE lubricant was carried out using a two-step method. Subsequently, the dispersion stability was assessed qualitatively and quantitatively. The samples were characterised by a volume concentration of 0.010%, with variations in the mixture ratio of 20:80, 40:60, 50:50, 60:40, and 80:20. Coefficient of friction (COF) and wear scar diameter (WSD) values were determined using the Koehler Four-ball Tribo Tester and Light Compound Microscopy. The investigation revealed that each sample experienced a reduction in COF, with the 40:60 ratio demonstrating the best ratio with the most significant decrease of 37.09%. At the same time, the COF decreased by 8.34%, 2.12%, 7.37%, and 15.11% for the nanolubricant samples at 20:80, 50:50, 60:40, and 80:20, respectively. The WSD evaluation showed that the 40:60 ratio has the lowest scar diameter of 0.0344 mm and a 37.09% wear rate decrease compared to pure lubricant. Each sample exhibits superior performance when evaluated for tribological characteristics and performance, particularly in the case of nanolubricants with the 40:60 ratio. The TiO2-SiO2/PVE, characterised by a volume concentration of 0.010%, has remarkable efficacy across different binary ratios, making it highly recommended with a 40:60 ratio for lubricating AAC compressor systems.

Operational stability influenced by lubricant oil charge in the CO2 automotive air conditioning system

In a vapor compression refrigeration system, the oil enhances the efficiency of the compressor but impairs the performance of the heat exchanger. This paper focuses on the experimental study of the influence of oil quantity on the operational stability of CO2 air conditioning system. The operational stability of the system under different oil charge quantity and operating conditions is studied. The experimental results indicate that when the oil circulation rate increases to a certain value, the adjustment of electronic expansion valve (EXV) opening or the compressor speed will cause system fluctuation and the outlet of evaporator gets close to no superheat. The critical oil circulation rate of the experimental system is about 9.2 %. The analysis of the fluctuation shows that it becomes more severe with the increasing of the refrigerant mass flow rate. When the mass flow rate increases from 210 kg∙h − 1 to 250 kg∙h − 1 at 7000 r min−1 of compressor speed, the fluctuation frequency increases from 0.072 Hz to 0.095 Hz. The occurrence of unstable phenomena has remarkable impact on system performance, the maximum difference of this system in instantaneous cooling capacity and COP during the fluctuation period is respectively 0.5 kW and 0.13.

A novel control method for the automotive CO2 heat pumps under inappropriate refrigerant charge conditions

CO2 heat pumps are increasingly widely used in automotive air conditioning, and the demand for refrigerant charge varies greatly under different modes and operation conditions. However, due to the limited space in vehicles, the accumulator cannot fully meet the refrigerant balance requirements for the variable operating conditions, and states of inappropriate refrigerant charge were frequently observed. To enhance system performance and safety under inappropriate charge conditions, an experimental setup and a mathematical model with a maximum error of 6 % were established to investigate the operating characteristics under inappropriate charge conditions. An investigation into the interplay among discharge pressure, the appropriate refrigerant charge range, and refrigerant distribution was conducted. It elucidated how refrigerant charging states (undercharged, adequately charged, or overcharged) manifest in terms of refrigerant distribution and optimal discharge pressure. A novel control method based on refrigerant distribution regulation has been proposed. The proposed control logic could increase the system IPLV by 36.8 % when the refrigerant charge deviates from the appropriate range by 12.12 %, and the greater the dysregulation in the refrigerant charge, the greater the improvement. This control logic would be more enhanced if dysregulation was considered.

Study of the Incidence of CO and CO2 Gas Emission Levels and Temperature, of the Automotive Air Conditioning System Inside an Interprovincial Bus at Different Environmental and Operating Conditions

The present curricular integration work proposes to analyze the levels of CO and CO2 gas emissions in the passenger compartment of an interprovincial bus, considering environmental and functional conditions, to obtain values that are analyzed, allowing to know the comfort conditions of the passenger, and considering an ideal temperature of 22∘C. The study was carried out on the selected route during the bus route, both in the central and peripheral urban sectors, where the influx of users is notable throughout the day. The field measurements were carried out (August 5-10), inside the passenger compartment of an interprovincial bus, considering operating variables of the automotive air conditioning system, such as condition, OFF, air recirculation, and air renewal. Data were collected in the passenger compartment’s front, middle, and rear sections. An IAQ TESTO 440 gas analyzer was used through the CO2 and the CO probe, located at a height of 1.1 m from the floor, which was considered as the average respiratory level of the passenger, generating the data in lapses of 10 min. Once the analysis has been carried out, the data is tabulated and the concentration levels of emissions produced by the users’ exhalation are determined. Finally, by tabulating the data, it was possible to know the concentration percentages of the gas emissions produced by the users, in the different locations of the passenger compartment. It is recommended that for future research, a study be carried out with data collected from a full day of travel. Keywords: Air conditioning, optimization, gas emissions, air quality, passenger cabin, comfort, gas analyzer, interprovincial transport. Resumen Este trabajo de integración interna propone analizar el CO2 y las emisiones de CO2 en el habitáculo de los autobuses interurbanos, teniendo en cuenta las condiciones ambientales y funcionales, para obtener los valores analizados, que permitan conocer el estado de confort del pasajero. Teniendo en cuenta la temperatura ideal de 22∘C. En la ruta seleccionada, el estudio se realizó a lo largo de la ruta del bus, tanto en la zona céntrica como en la semiurbana donde hay una gran cantidad de usuarios a lo largo del día. Se realizaron mediciones de campo (del 5 al 10 de agosto) al interior del habitáculo de un bus interurbano, teniendo en cuenta variables operativas del sistema de aire acondicionado del vehículo como condición, apagado, recirculación de aire y cambio de aire. Los datos se recopilan en las partes delantera, media y trasera de la cabina. El analizador de gases IAQ TESTO 440 se utiliza como medio para los detectores de CO2 y CO, colocado a una altura de 1,1 metros del estanque, que se considera la frecuencia respiratoria media del pasajero, produce datos en un tiempo breve en 10 minutos. Una vez que se completa el análisis, se tabulan los datos y se determina la concentración exhalada del usuario. Finalmente, es posible conocer el porcentaje de emisiones generadas por el usuario, en diferentes puntos del habitáculo. Se recomienda que se realice un estudio con los datos recopilados en el transcurso de un día de viaje para futuras investigaciones.

Silver Nanowire-PVB Composite for Reflective Heat Coating

Automotive air conditioning (AAC) is essential, particularly in tropical countries like the Philippines, where temperatures can go beyond 40 °C during the summer. AAC system is installed for the comfort and safety of passengers. However, AAC may consume up to 30% of the fuel and increase fuel consumption by up to 20%. Consequently, increasing fuel consumption can lead to high costs and greenhouse emissions worldwide. Commercially available car tints can block harmful ultraviolet (UV) rays but selectively block IR rays which primarily cause heating. Therefore, sustainable cooling solutions must be developed. This study developed a silver nanowire (AgNW)-PVB (polyvinyl butyral) composite spray coating. The coating decreased the transmittance by at least 30% in the UV region and at least 25% in the near-infrared (NIR). Average transmittance in the visible region (Vis) is as much as 63.50% which highly depends on the concentration of PVB and AgNWs. More AgNWs decrease the transmittance at UV, Vis, and NIR regions.

Performance evaluation of ecofriendly R1234ze(E) refrigerant in an automotive air conditioning system

AbstractA mathematical model for an air conditioning system used in five‐seater cars is developed with R1234ze(E) and R134a refrigerants, consisting of real system geometry like an evaporator, compressor, condenser, and thermostatic expansion valve. The mathematical model includes refrigerant properties, heat transfer, and pressure loss correlations for two‐phase and single‐phase regions. The performance parameters of a system like evaporator cooling duty, condenser heat loss, compressor power, refrigerant flow rate, and compressor volumetric efficiency obtained from a mathematical model are validated with the results of an experimental facility developed with R134a. The uncertainty analysis performed for the testing facility showed below 11% deviation. The simulation and experimental results showed an overall 10%–15% difference. It is found that the experimental cooling capacity with R134a and numerical cooling capacity with R134a show a 4%–12% variation, experimental cooling capacity with R134a and numerical cooling capacity with R1234ze(E) show a 7%–20% variation, and numerical cooling capacity with R134a and numerical cooling capacity with R1234ze(E) show a 5%–15% variation for the given range of compressor speed (500–1500 rpm), and condensing temperature (26–45°C). The study concluded that R1234ze(E) could potentially replace R134a because it has similar thermophysical properties and an average performance difference of up to 10% with R134a. Due to the limitations of the electric motor used to drive the compressor, tests in the current study were conducted at modest compressor speeds (500–1500 rpm). Future research will focus on experiments with high compressor speed (in the range of 1500–4000 rpm) and R1234yf and R1234ze(E) refrigerants for performance evaluation of automobile air conditioning systems.

Design of a Cold Storage with R507A Refrigerant for the Preservation of Twenty-Five Tons of Apples in the Ankara Province

In the absence of proper humidity and temperature conditions, undried fresh foods will experience physiological and biological deterioration, resulting in mass loss and the development of mold. Thanks to this rationale, humanity has endeavored to keep food products from deteriorating. This can be observed through the use of cold rooms constructed by the Ancient Romans using clay and the cooling chambers known as "Yakhchāl" developed by the Persians. The advancement of refrigeration technology has persisted since the era of ancient civilizations. The advent of refrigeration cycles has significantly streamlined the implementation of containment technology. The presence of these systems in residential settings can be attributed to the development of the vapor compression refrigeration cycle and the compact nature of this technology, which enables convenient freezing or cooling of products for storage purposes. Vapor compression refrigeration cycles are still widely employed in various applications, such as office and automotive air conditioning systems, refrigerators, and industrial cold rooms. This study aims to develop an industrial cold room design tailored explicitly for storing and transporting apples, a perishable agricultural commodity. The primary objective is to ensure that the apples are maintained in optimal humidity and temperature conditions, thereby preventing any degradation, even when handling large quantities in Ankara.

Flow field analysis and noise characteristics of an automotive cooling fan at different speeds

As the core component of the automotive air conditioning cooling system, the automotive cooling fan directly affects the cooling performance of the entire system. Therefore, it is necessary to study the flow field and noise of the automotive cooling fan. This study focuses on the analysis off low field characteristics and noise generation in an automotive air conditioning systems, specifically related to an automobile cooling fan at different speeds. The flow field properties of the fan are examined through the distribution off low line trajectory, pressure distribution on the blade surface, and velocity distribution characteristics at various speeds. The analysis reveals that the maximum air velocity occurs at the point where the fan blade meets the wind guard, while the maximum pressure is observed at this point and at the edge where the fan blade cuts through the cavity. Furthermore, a monitoring point located 1 m in front of the fan is selected to study the average value of fan pneumatic noise pulsation and generate a noise cloud map, aiming to identify the main noise source of the fan. To better understand the noise distribution and variation at different speeds, various noise metrics are utilized, including noise Sound Pressure Level (SPL) spectrum, 1/3-octave SPL spectrum, and 1/3-octave A-weighted SPL spectrum. The noise characterization results indicate that the primary areas of fan noise generation are located at the tip of the leaf margin of the forward swept wing. This research provides valuable insights for the improvement and optimization of the cooling fan design, as well as subsequent noise reduction efforts.

Applicability evaluation of internal heat exchanger in CO2 transcritical cycle considering compressor operation boundaries

CO2 transcritical cycle has been widely promoted as a green energy utilization technology. Internal heat exchanger (IHX) is under consideration for cycle efficiency improvement. However, the interaction between IHX and compressor in CO2 cycle has not yet been fully explored. In this regard, compressor operating boundaries are introduced as constraints to IHX applicability evaluation in CO2 cycle. It indicates that considering compressor limits, IHX can either benefit or attenuate the CO2 cycle performance, depending on operating conditions. By reducing optimal discharge pressure, IHX helps CO2 cycle avoid the upper pressure limit, further improving performance by 5%. Over a wide range, however, IHX increases compressor discharge temperature, indirectly resulting in up to 50% performance degradation. The major factors affecting the duality of IHX in CO2 cycle are compressor discharge temperature limit, IHX efficiency and motor heat loss. Finally, performance-oriented IHX design guidelines for mainstream single-stage CO2 applications are provided. For automotive air conditioner, optimum IHX efficiency improves cycle performance by up to 30% in cooling mode. By contrast, IHX contribution is negligible in heating mode. For heat pump water heater and refrigeration system, both can benefit from IHX, particularly when compressor discharge temperature tolerance is high.

Energy and Exergy Analysis on Zeotropic Refrigerants R-455A and R-463A as Alternatives for R-744 in Automotive Air-Conditioning System (AACs)

The popularity of vehicles and the increased time spent in cars with air conditioning systems has led to regulations in many countries that require the use of environmentally friendly refrigerants with minimal global warming and zero ozone depletion potential (GWP and ODP). Cars need high-performance, eco-friendly air conditioning systems to reduce their impact on the environment, lower fuel consumption, and decrease carbon emissions. The aim of the current work was to propose CO2-based blend zeotropic refrigerants, R-455A (R-744/32/1234yf) and R-463A (R-744/32/125/1234yf/134a), to improve the thermodynamic performance of pure CO2 refrigerants. The thermodynamic energy and exergy analysis and system optimization of an AAC system for the new zeotropic refrigerant blends compared to carbon dioxide (R-744), using Aspen HYSYS software, were investigated. The influence of cooler/condenser pressure, average evaporator temperature, cooler/condenser outlet temperature, and refrigerant flow rate on the cycles’ COP and exergy efficiency were conducted and are presented. The results showed that, at the same operating condition parameters, the cycle COP improved by 57.6 and 76.5% when using R455A and R463A instated of R744, respectively, with the advantage of reducing leakage problems due to the higher operating pressure of R744 (5–7 times higher than those of R455A and R463A), as well as requiring heavy equipment, but at optimal operating condition parameters, R744 and R-463A had a maximum COP of 14.58 and 14.19, respectively. The maximum COPs of R744, R455A, and R463A based on the optimal pressure of the cooler/condenser were 3.1, 4.25, and 5.4, respectively. Additionally, regarding the need for environmentally friendly air conditioning systems with acceptable performance in cars due to their impact on the environment and their contribution to global warming, the blend R455A is recommended for use as a refrigerant in AAC systems.

Adsorption Air-Conditioning for Automotive Applications: A Critical Review

The automotive industry seeks innovative solutions for energy-efficient and sustainable vehicles. Conventional air-conditioning systems consume significant energy and have environmental impacts. Adsorption technology offers a promising alternative with higher energy efficiency and reduced emissions. This review analyzes recent advancements in adsorption air-conditioning for automotive applications, including material selection and system integration. It discusses the benefits, challenges, environmental impact, and waste heat recovery potential of adsorption systems. This review explores emerging trends like hybridization with vapour-compression (VC) systems to optimize energy efficiency and sustainability. By evaluating the existing literature, this review provides insights into thermally driven technologies for automotive air-conditioning.

Research on evaporative cooling to improve the performance of automobile air conditioners

In this study, an evaporative cooling device (ED) was developed using the evaporative cooling pad (EP) made of cellulose-based materials with related accessories to actually install on a condenser of the automotive air conditioner (MAC) to improve the operating performance of HR-12 MAC. The ED was used to pre-cool the air entering the condenser by evaporative cooling instead of directly spraying water to cool the condenser. This approach can effectively reduce the risk of condenser corrosion and contamination. The HR-12 MAC performance was assessed at three different outdoor ambient temperatures (Toa: 30 °C, 35 °C, and 40 °C) and EP thicknesses (3 cm, 5 cm, and 7 cm). The configuration of the optimum EP thickness was identified through the results of HR-12 MAC performance experiments. The operating performance of HR-12 MAC with ED improved with the increase in Toa and EP thickness. However, according to most test results, ED could not effectively improve the performance of HR-12 MAC at the Toa of 30 °C. Under optimal conditions, the coefficient of performance (COP) of the refrigeration system and the energy efficiency ratio (EER) of the air conditioning system of HR-12 MAC with ED were respectively 7.76% and 13.09% higher than the original HR-12 MAC at the Toa of 40 °C, and the EP thickness of 7 cm.

Improving Automotive Air Conditioning System Performance Using Composite Nano-Lubricants and Fuzzy Modeling Optimization

This study aims to enhance the effectiveness of automobile air conditioning (AAC) systems through the use of composite nano-lubricants and fuzzy modeling optimization techniques. Composite nano-lubricants, which consist of varied metal oxide ingredients and content ratios, are projected to surpass single-component nano-lubricants in terms of improving the performance of AAC systems. Fuzzy modeling is used to simulate the AAC system based on experimental data using three input parameters: volume concentration of nano-lubricants (%), the refrigerant charge (g), and compressor speed (rpm). The output performance of the AAC system is measured using four parameters: cooling capacity (CC) in kW, compressor work (CW) in kJ/kg, coefficient of performance (COP), and power consumption (PC) in kW. Optimization is performed using the marine predators algorithm (MPA) to identify the best values for the input control parameters. The objective function is to minimize CW, COP, and PC while simultaneously maximizing CC and COP. Results showed that the performance of the AAC system improved from 85% to 88% compared to the experimental dataset, highlighting the potential benefits of using composite nano-lubricants and fuzzy modeling optimization for improving the energy efficiency of AAC systems. Furthermore, a comprehensive comparison with ANOVA was performed to demonstrate the superiority of the fuzzy modeling approach. The results indicate that the fuzzy model outperforms ANOVA, as evidenced by a reduced root mean square error (RMSE) for all data, from 0.412 using ANOVA to 0.0572 using fuzzy. Additionally, the coefficient of determination for training increased from 0.9207 with ANOVA to 1.0 with fuzzy, further substantiating the success of the fuzzy modeling phase.

HVAC Noise Prediction Using Lighthill Wave Method

Automotive Heating Ventilation and Air Conditioning (HVAC) system is an essential component in providing thermal comfort to the cabin occupants. The HVAC noise which is typically not the main noise source in ICE vehicles, is considered to be one of the dominant sources in the electric vehicle (EVs) cabin interiors. As air is delivered through ducts and registers into the cabin, it will create an air-rush/broadband noise and in addition to that, any sharp edges or gaps in flow path can generate monotone/tonal noise. Noise emanating from the HVAC system can be reduced by optimizing the airflow path by the use of virtual analysis during the development stage. This paper mainly focuses on predicting the noise from the HVAC ducts and registers. In this study, Noise simulations were carried out with Ducts and Registers. An FVM based 3-Dimensional (3D) CFD solver was used for flow as well as acoustic simulation. Large Eddy Simulation (LES) was used for flow field generation and noise characteristics were studied using Lighthill Wave method which is a hybrid aeroacoustic approach that can provide results with a quick turnaround time and low computational power. The frequency response of the aeroacoustic noise from the ducts and registers were predicted using the simulations and the models were compared in terms of Overall Average Sound Pressure Level (OASPL). The simulated spectra exhibit good correlation with the test data.

Energetic performance evaluation of an automotive CO2 air conditioning system with a dual-evaporator configuration

Inefficient performance of CO2 refrigerant in hot climates has become a major obstacle to its wide application in electric vehicles. In this paper, the vacant heating core in cooling mode was exploited to increase the heat transfer area of evaporator and improve system performance. With the aid of a validated evaporator model and an experimental test rig, performance improvements brought by this added area were evaluated. Results indicated that this area is not suggested to be directly added to cooling core. This necessitates a dual-evaporator (D-E) configuration. For case I (small CO2 pressure drop), the growth rate in heat transfer rate brought by D-E configuration is 19∼20% and less sensitive to parallel or series operation. Nevertheless, this growth rate for case II (large CO2 pressure drop) is greatly affected, 30.6∼32.6% for parallel operation and 7.5∼17.6% for series operation. Specifically, it is around 17.5% and 7.5∼13.6% for series cross-parallel and cross-counter arrangements, respectively. By comprehensive consideration, the cross-parallel arrangement is recommended to be adopted. Experimental results indicated that the cross-parallel D-E configuration greatly increases the evaporation temperature and exhibits a slight impact on optimum high pressure within the transcritical cycle. The enhancement in COP brought by this configuration is around 6∼12% without additional cost, and it rises with the decreased air flowrate through evaporator and air velocity through gas cooler and the increased ambient temperature. This indicates that this configuration is an effective and economical technology to alleviate the efficiency degradation issue of transcritical CO2 automotive air-conditioners.

Energy saving potential of an innovative membrane contactor hybrid system for vehicles’ climate control

In this paper an innovative Membrane Contactor Hybrid System (MCHS) for automotive air conditioning is presented and its energy needs are evaluated and compared with those of a traditional system for internal combustion engine vehicles and hybrid ones. The proposed system joints a Vapor Compression Cycle (VCC) with a Liquid Desiccant Cycle (LDC) provided with innovative Three-Fluid Membrane Contactors (3F-MCs). These components are crossed by air, liquid desiccant and a third fluid operating as an internal heat source/sink to control the desiccant temperature. The VCC refrigerant undergoes a two-stage compression process: the lower level is used in a conventional evaporator for cooling the air, and the higher level in an absorption 3F-MC to dehumidify the renewal air. A second 3F-MC (desorber) is heated (by means of hot water derived from the vehicle’s engine) in order to reconcentrate the desiccant by discharging water vapor to the environment. Air temperatures between 26 and 32 °C and relative humidity in the range 40–80% are considered to perform the comparisons between the two systems. Results show that energy savings can exceed 40% in the case of the most severe external conditions.

Establishment of HFC-134a Emission Inventory in the North China Plain from 1995 to 2020

1,1,1,2-tetrafluoroethane (HFC-134a) is a potent greenhouse gas that can be degraded to produce trifluoroacetic acid (TFA), a degradation product that has an impact on aquatic ecology, so its emission has been a continuous concern worldwide. Existing studies mainly estimate the global- or national-scale emissions of HFC-134a, and there are relatively few studies on regional emissions, all of which used the top-down method. By establishing a regional-scale bottom-up emission inventory and comparing it with the regional-scale top-down estimation results, regional emissions can be verified and their emission characteristics and environmental impacts can be analysed. HFC-134 emissions were estimated for the first time in the North China Plain using the emission factor method, and spatiotemporal characteristics and environmental impacts were analysed for the period of 1995 to 2020. The results showed that the cumulative HFC-134a emissions were 88 (73–103) kt (126 Mt CO2-eq), which have led to an increase in global radiative forcing of 1.1 × 10−3 (0.9 × 10−3–1.3 × 10−3) W m−2, an increase in global surface temperature of 8.9 × 10−4 °C, and a cumulative TFA production of 7.5 (6.2–8.9) kt as of 2020. The major sources of HFC-134a emissions are the refrigeration and air conditioning sector, which involves the automotive air conditioning (MAC), industrial and commercial refrigeration, and air conditioning (ICR) sub-sectors. China joined the Kigali Amendment in 2021 to phase down HFCs and proposed the goal of carbon neutrality by 2060. The North China Plain is a region undergoing rapid economic development, with a relatively high proportion of GDP (29%) and car ownership (23%) in 2020. Additionally, HFC-134a emissions accounted for about 20% of the total emissions in China. Therefore, HFC-134a emissions and their environmental impact on the North China Plain should not be ignored.

Finite Element Analysis of Thermal Management Automobile Unit

In order to verify the rationality of the structural design scheme of the battery thermal management unit for a new energy vehicle, this paper uses SolidWorks to establish the geometric model of the device, and conducts harmonic response analysis of the unit according to the vibration test requirements specified in the standard for automotive air conditioners, and obtains the modal frequencies, modal shapes, and structural stress distribution of the unit. The results show that under the specified load, the stress of each part of the structure does not exceed the material yield strength, and the structure as a whole meets the design requirements, achieving the purpose of verification.