Influencing Factors And Improvement Methods Of Waste Heat Utilization In Thermoelectric Power Generation System

In case of the energy crisis and environmental pollution,thermoelectric technology,as an important method of saving energy and reducing emission has received a lot of attentions from researchers.The thermoelectric technology is wildly employed in the automotive exhaust heat recycling and solar energy applications.However,due to the low performance of thermoelectric materials and the unsatisfactory structure of thermoelectric components,low output performance of thermoelectric generation is still a significant issue needed to be handled in the practical application.One of the important ideas to solve this problem is to match the thermoelectric device with its application environment by optimizing the heat transfer parameters between the hot and cold sides of the thermoelectric system.The temperature difference between the thermoelectric device hot and cold sides is the fundamental parameters in the electrical output of the thermoelectric system.The main factors affecting the temperature difference between the two sides of the thermoelectric device are the hot and cold sides temperature and the contact thermal resistance between the thermoelectric device and the system.Therefore,this paper presented a novel automotive exhaust heat recovery system and a photovoltaic-heat pump-thermoelectric system to investigate the best matching relationship between the hot and cold sides temperatures and the contact thermal resistance between the thermoelectric device and the system.The aim of these investigation is to maximize the temperature difference between the two sides of the thermoelectric device and improve the power generation performance of the thermoelectric system.The main contents of this study are as follows:(1)The temperature and flow rate of the heat transfer medium at the hot and cold sides of the system are optimized,the heat transfer between the thermoelectric device and the hot and cold ends of the system can be effectively enhanced.Therefore,the temperature difference between the two sides of the thermoelectric device and the electrical output of the thermoelectric system are increased.(2)Reducing the contact thermal resistance between the thermoelectric device surface and other system device can increase the thermoelectric power output of the system effectively.Optimizing the contact thermal resistance of the thermoelectric device hot side will increase the output power of the thermoelectric device more.(3)Reducing the thermal contact resistance between both sides of the thermoelectric device and the system can significantly increase the temperature difference between the hot and cold sides and enhance the output power of the thermoelectric system.However,this process can increase the heat transfer in the whole system.The energy from the heat source will be delivered to environment too effectively and released.Therefore,energy conversion efficiency will be reduced.The adjustment relation between improving thermal contact resistance and obtaining high energy conversion efficiency is illustrated in this study.