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Simulation based identification of the ideal defrost start time for a heat pump system for electric vehicles |
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| Affiliation: | 1. Virtual Vehicle Research Center, 8010 Graz, Austria;2. Graz University of Technology, Institute of Thermal Engineering, 8010 Graz, Austria;1. Department of Building Environment and Facility Engineering, College of Architecture and Civil Engineering, Beijing University of Technology, No.100 Pingleyuan, Chaoyang District, Beijing 100124, China;2. Department of Building Services Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR;1. Beijing Key Laboratory of Thermal Science and Technology and Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 100190 Beijing, China;2. University of Chinese Academy of Sciences, Beijing, China;3. China FAQ Group Corporation R&D Center, Changchun, China;4. The Catholic University of Cuenca, Ecuador;1. School of Energy & Environmental, Zhongyuan University of Technology, Zhengzhou 450007, China;2. Fluids & Thermal Engineering Research Group, Faculty of Engineering, University of Nottingham, UK;3. China Aviation Lithium Battery CO., LTD., Luoyang 471000, China |
| Abstract: | Resistance heating with PTC elements to cover the heat demand of electric vehicles reduces significantly the cruising range at low outside temperatures. Reversible heat pump systems are one of the most promising solutions for this problem. However, in heat pump mode the frost formation on the exterior heat exchanger reduces the performance and efficiency of the system. Therefore, an efficient defrost method is crucial to benefit from the heat pump also under frosting conditions. In the present paper, a transient Modelica simulation model of a reversible CO2-heat pump system with hot gas defrost was set up in order to assess the impact of different defrost start times. The model is able to handle frost growth on the exterior heat exchanger as well as defrosting. The simulation results showed an optimal point of time to conduct defrost at chosen operating conditions in order to maximize the average COP including the frosting and defrost period. |
| Keywords: | Air-to-air heat pump Defrost Hot gas bypass Electric vehicle Carbon dioxide Simulation Pompe à chaleur air-air Dégivrage Bypass à gaz chaud Véhicule électrique Dioxyde de carbone Simulation |
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