Abstract

[EN] Air-conditioning (AC) is an important sub-system in electric vehicles (EVs). AC is responsible for the highest energy consumption among all the auxiliary systems. As the energy is delivered by the batteries, the power consumption for airconditioning can imply a significant reduction of the vehicle autonomy. Given the actual state of the art and the temperature and power requirements, electrically driven compressors are the most feasible solution. However, vapour-compression systems are reaching their maximum efficiency. Using innovative technologies can improve the performance of standard systems and hereby increase the vehicle autonomy. This paper presents the first steps in the design of a magnetocaloric air-conditioner for an electric minibus. The system will include two reversible magnetocaloric heat pumps, one in the front part of a minibus and one on the rear. The heat rejection system of the power electronics will be coupled to the air-conditioning system. In order to assist the design of the system, a dynamic model has been developed for the cabin, the hydraulic loops and heat exchangers, and the magnetocaloric units. An integrated design of the complete system is necessary, as it will work under dynamic conditions which depend on the thermal load in the cabin. In this paper, the operation conditions of the magnetocaloric units are presented and the design of the magnetocaloric air-conditioner is discussed. This work has been developed under the frame of the European Project ICE which aims to develop an innovative mobile air-conditioning system for EVs based on a magnetocaloric heat pump. This work has been supported by the European Commission under the 7th European Community framework program as part of the ICE project “MagnetoCaloric Refrigeration for Efficient Electric Air-Conditioning”, Grant Agreement no. 265434. B. Torregrosa-Jaime acknowledges the Spanish Science and Innovation Ministry (Ministerio de Ciencia e Innovación) for receiving the Research Fellowship FPU ref. AP2010-2160. Torregrosa-Jaime, B.; Vasile-Müller, C.; Risser, M.; Muller, C.; Corberán, JM.; Payá Herrero, J. (2013). Application of Magnetocaloric Heat Pumps in Mobile Air-Conditioning. SAE International Journal of Passenger Cars. Mechanical Systems. 6(2):520-528. https://doi.org/10.4271/2013-01-0239 S 520 528 6 2

Abstract

[EN] Among all the auxiliary components in conventional and electric vehicles, air-conditioning (AC) systems present the highest energy consumption. In fully electrical vehicles (FEVs), the heating of the cabin becomes an additional challenge as there is less waste heat available. Therefore, a careful design of the air-conditioning system and of the operation strategies is necessary to reach a reasonable FEV autonomy without compromising the thermal comfort. This paper presents a tool for the design, analysis and optimization of an efficient air-conditioning system for an electric minibus. It consists of dynamic models of each component of the system that have been developed and fully validated individually. Finally, they have been coupled together to simulate the overall vehicle performance of the vehicle in MATLAB-SIMULINK. The core of the system is a water-to-water reversible heat pump with a variable speed compressor. The internal water loop connects the heat pump to the air-coolers inside the cabin while the external water loop is integrated within the heat rejection system of the power electronics. An automatic control system regulates the speed of the compressor, the blowers and the circulation pumps to reach thermal comfort. The power consumption has been analysed under different working conditions and control settings using the overall vehicle model. The latter is a powerful tool not only to design and select MAC equipment, but also to find the most efficient operation strategies. This work has been supported by the European Commission under the 7th European Community framework program as part of the ICE project “MagnetoCaloric Refrigeration for Efficient Electric Air-Conditioning”, Grant Agreement no. 265434.B. Torregrosa-Jaime acknowledges the Spanish Science and Innovation Ministry (Ministerio de Ciencia e Innovación) for receiving the Research Fellowship FPU ref. AP2010-2160. Torregrosa-Jaime, B.; Payá Herreo, J.; Corberán, JM. (2013). Design of Efficient Air-Conditioning Systems for Electric Vehicles. SAE International Journal of Alternative Powertrains. 2(2):291-303. https://doi.org/10.4271/2013-01-0864 S 291 303 2 2