Experimental Study Of Thermoelectric Power Generation System And Its Application

Waste heat is an important source of energy. With the energy crisis is worsening; waste heat recycling is increasingly becoming the focus of attention of researchers. According to the report of U.S. Department of Energy, the loss of industrial waste heat energy in U.S for one year equivalents to energy use of500million Americans during one year, it costs nearly ten billion U.S. dollarsto processing waste heat all over the world.In most developed countries with temperate climate, heat for space heating and domestic hotwater is often provided by burning gas or oil in a boiler or furnace. Current condensingboilers are highly efficient achieving thermal efficiencies in excess of90%with combustiongases rejected at dew point temperature. Despite a growing market for condensing boilers, alarge number of old boilers are still being used with thermal efficiency as low as55%, resulting in large energy loss. As the fastest growing automotive market in the world, with the high-speed development in the automotive industry, China has to face the various pressures and worriesis brought by the rapidly increasing motor vehicles owned quantity. According to the current assessment of vehicle engine, about60%of the fuel energy is not used effectively. If approximately6%of the exhaust heat were converted into electrical power, it would be possible to reduce the fuel consumption around10%. The mature and widely used Hybrid vehicle technology also adds electricity demand to the vehicle.Thermoelectric power generation (TEG) is not only a green energy technology, but also a new type of power generation. In this field, renowned international energy giants have been walking in the forefront of research. This generator can convert domestic or automobile waste heat into electricity, save energy while reduce harmful emissions. It is a promising direction for future renewable power technology upgrades.With the funding of the European Union’s new energy projects, for enhancing China R&D in the field of thermoelectric power generation, a domestic thermoelectric cogeneration system (TCS) which usesavailable heat sources in domestic environment to generate electricity and produce pre-heated water for home use is presented. On the basis of the limited publicly available information by advanced foreign auto manufacturing enterprises, a novel prototype for thermoelectric power generation from vehicle exhaust is also proposed. After system modeling, an experiment structure is also built and tested for further study. Results of both theoretic analysis and experiment show reasonability of this prototype employed for exhaust heat recovery.Firstly, models of single-stage TEG and two-stage TEG system are established. The main parameters of the reaction TEG system performance are also determined based on the models. After rationality of the models are verified by comparison with experimental data, the TEG system models can be used for simulation and calculation of performance improvement and optimization. Then, calculation of the exhaust heat exchange shows that the heat transfer enhancement means, such as installing finned on the tube’s inner wall, is necessary. Serrated fin is selected based on the simulation of several different types of fins.Thirdly, for different heat-conducting oil thickness, temperature field distribution of TEG unit is simulated. In addition, the most suitable thickness of the heat-conducting oil is determined from the simulation results. Then, the external dimensions of the construction will be finalized.After that, as the main research directions to improve the the system performance, heat pipe is introduced to two-stage TEG unit. Moreover, design calculation and verification calculation is finished according to the set parameters.Fifthly, a TEG test rig is built based on the calculations and simulations. Then, single stage TEG system, two-stage TEG system and two-stage TEG system employing heat pipe are tested. Considering to the manufacturing cost, the economic value of the prototype is also analysed. Although cost more, the two stage TEG system thermal efficiency can reach5.35%. It is improved by32%compared to single stage TEG’s4.04%in the same operating conditions. Results of both theoretic analysis and experiment show reasonability of this prototype employed for exhaust heat recovery.Finally, a domestic thermoelectric cogeneration system (TCS) is presented. The feasibility and significant improvement on system thermal efficiency is verified through the micro-scale test rig.