Bárbara Torregrosa-Jaime

Design of Efficient Air-Conditioning Systems for Electric Vehicles

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 Innovacion) for receiving the Research Fellowship FPU ref. AP2010-2160.

Application of Magnetocaloric Heat Pumps in Mobile Air-Conditioning

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 air-conditioning 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.

Application of magnetic cooling in electric vehicles

The features of an active magnetic regenerator refrigerator are determined for its application in mobile air-conditioning systems. The thermal requirements of an electric vehicle have first been obtained and result in a cooling demand of 3.03 kW at a temperature span of 29.3 K. A comprehensive parametric study has been conducted in order to find the active magnetic regenerator refrigerator design and working parameters that fulfill the vehicle needs with a minimum electric consumption and device mass. Specifically, a permanent-magnet parallel-plate active magnetic regenerator refrigerator made of Gd-like materials is considered. According to the possibilities of current prototypes, in the study the cycle frequencies have been limited to 10 Hz and the applied magnetic fields, to 1.4 T. The results show that an active magnetic regenerator refrigerator made of plates between 30 and 40 μm thick and channels between 20 and 40 μm high could meet the vehicle demand with a coefficient of performance between 2 and 4 and a total mass between 20 and 50 kg. Compared to vapor-compression devices for mobile air-conditioning systems (coefficient of performance = 2.5 and mass 12 to 15 kg), the active magnetic regenerator refrigerator works optimally with fluid flow rates at least three times larger. In order to integrate active magnetic regenerator refrigerators into mobile air-conditioning systems, the hydraulic loops should be consequently redesigned.