Performance Characteristics of PTC Elements for an Electric Vehicle Heating System
A high-voltage positive temperature coefficient (PTC) heater has a simple structure and a swift response. Therefore, for cabin heating in electric vehicles (EVs), such heaters are used either on their own or with a heat pump system. In this study, the sintering process in the manufacturing of PTC elements for an EV heating system was improved to enhance surface uniformity. The electrode production process entailing thin-film sputtering deposition was applied to ensure the high heating performance of PTC elements and reduce the electrode thickness. The allowable voltage and surface heat temperature of the high-voltage PTC elements with thin-film electrodes were 800 V and 172 °C, respectively. The electrode layer thickness was uniform at approximately 3.8 μm or less, approximately 69% less electrode materials were required compared to that before process improvement. Furthermore, a heater for the EV heating system was manufactured using the developed high-voltage PTC elements to verify performance and reliability.
The solutions to electric vehicle air conditioning systems: A review
Abstract The air conditioning (AC) system provides cool, heating and ventilation in the cabin of the electric vehicles (EVs). It is necessary to control the interior thermal environments of the vehicle and ensure safety in visibility. Because AC systems are electrically powered, vehicle range is reduced drastically when the AC system is operating. EVs present a particular challenge to the development of more efficient AC systems for automotive applications. In this paper, the state of the art for various AC system solutions to EVs was critically reviewed. The investigations of alternative solutions are continuing along many parallel routes, e.g. vapor compression refrigeration-dedicated heater AC systems, reversible vapor compression heat pump AC systems, non-vapor compression AC systems and integrated thermal management system combined AC and battery pack. The characteristics and particular applications of each solution have been extensively discussed. Finally, a comparison listing the various pros and cons of the different available solutions was presented.
PERFORMANCE OF R-1234YF IN MOBILE AIR CONDITIONING SYSTEM UNDER DIFFERENT HEAT LOAD CONDITIONS
"Drop-in" tests of R-1234yf in a mobile air conditioning (MAC) system were conducted, and the system performance results were compared with those of the same system using R-134a. The performance tests were performed in a psychrometric calorimeter test facility based on enthalpy-difference method. The system performance was investigated under low-, middle- and high-load conditions. The results showed that the optimum refrigerant charge of R-1234yf was approximately 90% compared with that of R-134a under the same MAC system. When operated under optimum refrigerant charge, the system cooling capacity and COP of R-1234yf was 11% and 8.3% lower than that of the R-134a system, respectively. When wind tunnel test was conducted on a practical vehicle, the result showed that the carriage temperature in the vehicle with the R-1234yf system dropped slower. The average carriage temperature and blower outlet temperature were 2°C higher than those of the R-134a system during the test.