Vehicle Air Conditioning System Research Articles

Study on leakage loss via the radial clearance in a double-swing vane compressor for electric vehicle air conditioning systems

The leakage loss in a novel double-swing vane compressor (DSVC) for use in electric vehicle air conditioning systems is theoretically analysed. The leakage flow through the radial clearance between the rotor and cylinder in the DSVC is modelled by considering both the section change of the leakage channel and the viscous friction of the working fluid. Under the same operating conditions and dimensions, the radial leakage loss of DSVC is more than that of the swing vane compressor (SVC) with a single swing vane. However, the theoretical suction volume of the DSVC is larger than that of the SVC. The relative volumetric leakage loss is almost equal to that of the SVC, which indicates that compared to the SVC, the effects of the structural changes of the DSVC on the volumetric efficiency is neglectable. Considering the larger work capacity and higher mechanical performance of the DSVC, it is suggested that the DSVC is a better choice for the electric vehicle air conditioning system.

Analysing the Effect of Temperature and Humidity on AC Compressor Speed Using Fuzzy Control over CAN Communication

Design of an autonomous in vehicle air conditioning system using fuzzy rule based is proposed in this paper. An air conditioning system, presently involves frequent starting and stopping of the compressor for desired temperature. However the desired compressor speed of the AC in the vehicle is depends on number of factors such as change in temperature and humidity of the environment throughout the day. Therefore, intelligent system using multiple CAN based sensors is proposed which measures the user temperature and humidity inside the vehicle. These input parameters are then used to control compressor speed which involved in decision making using Mamdani type of fuzzy inference system. Data driven CAN based fuzzy system is employed to get the crisp values of different controlling parameters.

Investigation on the Performance of a Compact Three-Fluid Combined Membrane Contactor for Dehumidification in Electric Vehicles

In this paper, the performance of a compact Three-Fluid Combined Membrane Contactor (3F-CMC) is investigated using Computational Fluid Dynamics (CFD), supported and validated with a good agreement by an experimental campaign made on a fully working prototype. This internally-cooled membrane contactor is the core component of a hybrid air conditioning system for electric vehicles (EVs) developed in a successful H2020 project called XERIC. In the adopted numerical approach, the conjugate heat and mass transfer inside the 3F-CMC is described by non-isothermal incompressible flows and vapor transport through a PTFE hydrophobic membrane. The sensitivity of the 3F-CMC performance to air/desiccant flow rates, temperature, humidity, and desiccant concentration is analyzed numerically through the validated CFD codes. According to this study, the moisture removal increases by the inlet humidity ratio, nearly linearly. Under the considered conditions (where the inlet air temperature is 26.2 °C), when the inlet relative humidity (RH) is 75% the moisture removal is about 450% higher than the case RH = 37%, while the absorption effectiveness declines about 45%. Furthermore, this study shows that the amount of absorbed vapor flux rises by increasing the airflow rate; on the other hand, the higher the airflow rate, the lower is the overall absorption efficiency of the 3F-CMC. This investigation gives important suggestions on how to properly operate a 3F-CMC in order to achieve the requested performance, especially in hot and humid climates.

Energy-saving effect of utilizing recirculated air in electric vehicle air conditioning system

The stock of electric vehicle is booming recently. However, the range of the electric vehicle is still a main barrier in its adoption. Air conditioning system is the second largest energy consumption device on vehicle, which will cause significant range reduction during operation. In this paper, the energy-saving effect of utilizing the recirculated air in air conditioning system is evaluated. The outside air ventilation rate based on CO2 limits and windshield anti-fog requirements are calculated, and the energy-saving effect of this strategy in 30 cities across China is evaluated using an annual energy consumption model. It is found that utilizing the recirculated air can save 14–46% heating energy when using PTC heater, and 33–57% heating energy in heat pump AC system. Throughout a year, utilizing the recirculated air can extend the driving range by 11–30%.

A Stochastic Model Predictive Controller Based on Combined Conditions of Air Conditioning System for Electric Vehicles

A stochastic model predictive controller based on combined conditions of air conditioning system is proposed to improve the energy efficiency of electric vehicles. According to the 25 groups of on-road tests, the velocity, solar radiation and temperature of driving conditions are recorded to construct combined conditions. A Markov chain-based combined conditions predictor is adopted to provide a prediction of the future conditions. In each predicted horizon, dynamic programming algorithm is applied to determine the best control strategy to balance the energy consumption and the cooling effect. The differences of three control strategies are compared in energy consumption and cooling effect, which are (i) the proposed SMPC method, (ii)a rule-based bang-bang controller and (iii) dynamicprogramming as the benchmark. Comparison resultsillustrate that, SMPC as an online method, theperformance is close to DP and is able to improve theAC energy economy by 7.86% than rule-basedcontroller.

Effect Of Engine Speed On The Performance Of Automotive Air Conditioning System Using R134a And R152a As Refrigerants

This paper presents a numerical approach in the investigation on the effect of engine speed on the performances of automotive air conditioning system using R134a and R152a as refrigerants. In the near future, R152a refrigerant is projected to replace R134a as working fluid in vehicle air conditioning systems. In this study, four engine rotations, i.e., 1000, 2000, 3000 and 4000 rpm that represent: idle, city, medium speed and high speed conditions, respectively, were investigated. In the modeling, the evaporating and condensing temperatures were assumed constant at 5°C and 45°C, respectively. The results showed that coefficient of performances (COPs) of the automotive air conditioning using R152a were higher than that of R134a for all engine speeds. The COP improvement of R152a increased with the increase in engine speed. At engine rotation of 4000 rpm, the COP improvement was by as much as 6.4%. The disadvantage of R152a compared to R134a was in its high discharge temperature. This condition is anticipated to affect the reliability of the compressor in the long run.

Selected issues in the field of electric vehicle equipment concerning the extension of the teaching and training programs

The article presents the extension of the measurement capabilities of two selected lab stands intended for the demonstration of a vehicle air conditioning system and automotive ignition systems. The modular structure of the stands allows to extend their measuring and research functionality of thermal imaging diagnostics. Such an extension of the scope of electrical equipment in stands also allows enrichment of the didactic program by expand of laboratory exercises. In the article was presented and discussed additional samples of thermograms taken at the stands.

Stochastic Model Predictive Control of Air Conditioning System for Electric Vehicles: Sensitivity Study, Comparison, and Improvement

A stochastic model predictive controller (SMPC) of air conditioning (AC) system is proposed to improve the energy efficiency of electric vehicles (EVs). A Markov-chain based velocity predictor is adopted to provide a sense of the future disturbances over the SMPC control horizon. The sensitivity of electrified AC plant to solar radiation, ambient temperature, and relative air flow speed is quantificationally analyzed from an energy efficiency perspective. Three control approaches are compared in terms of the electricity consumption, cabin temperature, and comfort fluctuation, which include the proposed SMPC method, a generally used bang-bang controller, and dynamic programming as the benchmark. Real solar radiation and ambient temperature data are measured to validate the effectiveness of the SMPC. Comparison results illustrate that SMPC is able to improve the AC energy economy by 12% compared to the rule-based controller. The cabin temperature variation is reduced by more than 50.4%, resulting with a much better cabin comfort.

Solar photovoltaic based air cooling system for vehicles

Abstract The conventional automotive air conditioning system was driven by internal combustion engine or power battery, which increased the oil consumption and vehicle carbon emission. In this study, a direct current (DC) air conditioning system powered by solar photovoltaic module (PV) has been designed to solve the problem of temperature increasing inside the vehicle when stops in the broiling summer. The purpose of this work is to design a whole DC air conditioning system with R134a as refrigerant, replacing the power source with solar energy. The result shows that the environmental condition in the vehicle has obviously improved by the DC air conditioning system, meeting the requirements of human bodies. In addition, in the experiment, the minimum refrigerating capacity should be ∼1500 W, maintaining the thermal equilibrium inside the vehicle under the sun blazing, when the vehicle stops and no person inside. The work will prompt further research of solar energy and development of solar electric vehicle air conditioning system.

Experimental investigation on using the electric vehicle air conditioning system for lithium-ion battery thermal management

It is investigated a lithium-ion battery thermal management (BTM) system using the electric vehicle (EV) air conditioning refrigerant to cool the battery pack directly. In the system, basic finned-tube heat exchanger structure and a special aluminum frame are adopted to design the battery pack thermal management module with lithium-ion batteries of cylindrical shape. The module is then integrated into the electric vehicle air conditioning system using two electronic expansion valves for the automatic control of the pack's temperature with self-programmed control software. Experimental results show that the BTM system can control the battery pack's temperature in an appropriate preset value easily under extreme ambient temperature, as high as 40 °C. In addition, through the refrigerant circuit optimization it can reduce the temperature non-uniformity inside the battery pack. The temperature difference within the pack is less than 4 °C in the constant discharge rate of 0.5 C, 1 C, 1.5 C laboratory tests, and 1.5 °C in road drive tests.

Study on energy saving effect of IHX on vehicle air conditioning system

In this paper, the performance of Internal Heat Exchanger (IHX) air conditioning system for R134a is investigated in bench test and vehicle test. Comparison for cooling capacity and energy consumption between IHX air conditioning system and traditional tube air conditioning system are conducted. The suction temperature and discharge temperature of compressor is also recorded. The results show that IHX air conditioning system has higher cooling capacity, the vent temperature decrease 2.3 °C in idle condition. But the suction temperature and discharge temperature of compressor increase 10°C. IHX air conditioning system has lower energy consumption than traditional tube air conditioning system. Under the experimental conditions in this paper, the application of IHX can significantly reduce the energy consumption of air conditioning system. At 25°C of environment temperature, AC system energy consumption decrease 14%, compressor energy consumption decrease 16%. At 37°C of environment temperature, AC system energy consumption decrease 16%, compressor energy consumption decrease 13%.

Air-conditioning system for vehicles with on-board hydrogen

Electric vehicles with on-board hydrogen store not only the corresponding chemical energy of the H2, but also a significant amount of potential energy in the pressurized gas. This energy is provided by a compressor at the fueling station and so far, it is wasted by throttling the H2 to the fuel cell supply pressure. An “open” metal hydride cooling system can convert part of this potential energy into cooling power. In this publication, results for an experimental lab-scale setup of such a cooling system are presented and discussed in the vehicle context. The lab-scale system consists of two plate heat exchanger based reactors filled with 335 g and 353 g of Hydralloy® C5 hydride material. At 10 °C an average cooling power of −532 W or −586 W could be determined for cycling times of 100 s or 75 s, respectively. Due to the small lab-scale reactors used in this study, this value is reduced to −76 W, when the efficient cooling power between 30 °C and 10 °C is determined. To conclude the results, scale-up effects and the relation of hydrogen flow and cooling power are discussed as well as a possible integration into a vehicle.

Annual energy consumption of electric vehicle air conditioning in China

As the largest energy consumption auxiliary device on the electric vehicle, the energy consumption of air conditioning system has a great impact on total energy efficiency. A comprehensive model is established in this article to evaluate the total annual energy consumption of electric vehicle air conditioning system in different cities across China. The major influencing factors, such as climate data, vehicle-use intensity, average driving speed and the performance of air conditioning system are taken into consideration based on a cabin thermal comfort and climate control load approach. With the model, the energy consumption of air conditioning system in light duty vehicles is analyzed in 30 province capital cities across China. The fit curves of heating energy consumption to latitude are also given. It is found that the energy consumption of air conditioning system varies largely in different cities, and the heat pump is capable of saving 41.03% heating energy in average.

Stochastic Dynamic Programming of Air Conditioning System for Electric Vehicles

Air conditioning (AC) system, as a main electricity consumption unit among the Electric vehicle (EV) auxiliary devices, has significant effects on the electricity efficiency of EVs. An energy management strategy is critical to distribute the energy more reasonable and extend the driving range. In this paper, a Stochastic Dynamic Programming (SDP) control strategy is used to optimize the electricity consumption of AC system. To study the relationship between solar radiation and electricity saving of AC system, a thermal model of the cabin and a mathematical model of AC system have been built. The electricity consumption using SDP algorithm is 10.35% less than using a rule-based controller. Additionally, the fluctuation of cabin temperature is considerably reduced with an AC system controlled by SDP.

Design and Cooling Performances of an Air Conditioning System with Two Parallel Refrigeration Cycles for a Special Purpose Vehicle

The objective of this study is to design and briefly investigate the cooling performances of an air conditioning system for a special purpose vehicle under various experimental conditions. An air conditioning system with two parallel refrigeration cycles consisting of two compressors and two condensers for satisfying the required cooling performance of the special purpose vehicle was tested under extremely hot weather conditions and high thermal load conditions and then optimized by varying the refrigerant charge amount. The optimum refrigerant charge amount of the tested air conditioning system was 1200 g with the consideration of the cooling speed and cooling capacity. The indoor temperatures of the suggested air conditioning system at the refrigerant charge amounts of 1200 g, 1400 g, and 1600 g were 24.7 °C, 25.2 °C, and 26.4 °C, respectively, at the elapsed time of 300 s. The cooling time required to reach a 15.0°C inner temperature in the suggested air conditioning system increased by 13.3% with the decrease of the refrigerant charge amount from 1600 g to 1200 g. The cooling capacity and the coefficient of performance (COP) of the suggested air conditioning system increased by 37.9% and 10.9%, respectively, due to a decrease of the refrigerant charge amount from 1600 g to 1200 g. The observed cooling performance characteristics of the air conditioning system with two parallel refrigeration cycles means it could be suitable for cabin cooling of special purpose vehicles. In addition, the designed special air conditioning system with two parallel refrigeration cycles for a special purpose vehicle was built to ensure a sufficient cooling performance for equipped passengers.

Design and dynamic analysis of a novel double-swing vane compressor for electric vehicle air conditioning systems

This paper presents a novel double-swing vane compressor (DSVC) for use in electric vehicle air conditioning systems. The design and work principle of the DSVC are introduced, and the dynamics and mechanical efficiency of the mechanism are theoretically formulated and analysed. Under the same operating conditions and dimensions, the theoretical volumetric flow rate of the DSVC is about 1.6 times that of the swing vane compressor (SVC) with a single swing vane and the mechanical efficiency of the DSVC is also greater than that of the SVC. The design of the double-swing vanes improves the load fluctuations on the eccentric and shaft bearings and enhances the operating smoothness of the compressor. Overall, the assessment of the structure and dynamics of the DSVC shows that the DSVC has the advantages of high efficiency, light weight and simple component geometries, which make it well suited to the requirements of electric vehicle air conditioning systems.

Experimental study on combined defrosting performance of heat pump air conditioning system for pure electric vehicle in low temperature

The development of defrosting technology is a crucial technical barrier to the application of the heat pump air conditioning system for the pure electric vehicle. The frosting on the air conditioning system significantly affects systematic performance and reliable operation especially in low temperature and high humidity climate condition. Therefore, in this paper, an experimental study of low-temperature heat pump air conditioning system with the combined defrost technology of increasing enthalpy and temperature is carried out to find proper thermal management solutions. Based on the reverse-cycle methods, the combined defrost technology makes full use of the compressor air-supplying enthalpy-adding, air-cooled heat exchanger inside the vehicle preheating, temperature-raising, enthalpy-adding and the external heat exchanger condensation temperature-increasing technologies. The fast defrosting process can be realized by means of releasing the condensation heat and volume significantly while the outer heat exchanger is conducting a defrosting operation. Meanwhile, the cold cabin sensitivity can be reduced while defrosting process taking place correspondingly. Experimental results show that under the operating condition of −20°C outside environment temperature and 80% relative humidity, instant defrosting time at fully defrosted air-cooled heat exchanger outside the vehicle can be controlled within 100s.

Investigation of Optimum Refrigerant Charge and Fans' Speed for a Vehicle Air Conditioning System

In this study, the performance evaluation and optimization of a recently developed battery-powered vehicle air conditioning (BPVAC) system is investigated. A mathematical model is developed to simulate the thermodynamic and heat transfer characteristics of the BPVAC system and calculate the coefficient of performance (COP). Utilizing environmental chambers and a number of measuring equipment, an experimental setup is built to validate the model accuracy and to conduct performance optimization by changing the charge of refrigerant in the system. The model is validated and employed for performance simulation and optimization in a wide range of speed for the evaporator and condenser fans. The modeling results verify that for any operating condition an optimum performance can be achieved by adjusting the speed of condenser and evaporator fans. The optimum refrigerant charge is obtained, and a potential improvement of 10.5% is calculated for the performance of system under ANSI/AHRI 210/240-2008 specifications.

Progress in Heat Pump Air Conditioning Systems for Electric Vehicles—A Review

Electric vehicles have become increasingly popular in recent years due to our limited natural resources. As a result, interest in climate control systems for electric vehicles is rising rapidly. According to a variety of research sources, the heat pump air conditioning system seems to be a potential climate control system for electric vehicles. In this paper, an extensive literature review has been performed on the progress in heat pump air conditioning systems for electric vehicles. First, a review of applications of alternative environmentally friendly refrigerants in electric vehicles is introduced. This is followed by a review of other advanced technologies, such as the inverter technology, innovative components and the system structure of the heat pump air conditioning system for electric vehicles. Lastly, recent developments in multiple source heat pump systems are presented. The use of these advanced technologies can provide not only sufficient refrigerating capacity for the electric vehicle, but also higher climate control system efficiency. We believe that ideal practical air conditioning for electric vehicles can be attained in the near future as the mentioned technical problems are gradually resolved.

Performance Analysis for Vehicle Air Conditioning System with Direct Current Compressor in Non-Electric Vehicle Using Fuzzy Logic Controller

Reducing fuel consumption and ensure occupants thermal comfort are two important considerations when designing a vehicle air conditioning system. By using direct current electric compressor, speed of compressor can be controlled by changing the frequency of the inverter. Fuzzy logic controller (FLC) was developed to imitate the performance of human expert operators by encoding their knowledge in the form of linguistic rules. The system is installed to a 5-door compact car with 1.2cc four-cylinder engine with data acquisition system to monitor the temperature of the cabin, coefficient of performance (COP) and fuel consumption. Temperature set-point of 22°C with original belt-driven, on/off and FLC electric direct current compressor at one hour experimental periods. The experimental results indicate that the FLC can save more fuel compared to on/off controller and belt-driven compressor.