Study On The Performance Of Self-adaptive Wall And Thermoelectric Air Conditioning System

External building envelope is an important factor affecting the building energy consumption. There are two shortcomings in traditional building envelope. On the one hand, due to setting fixed thermal physical parameters, there exists contradiction between thermal insulation and heat dissipation in traditional building envelope, causing buildings cannot realize their own heat balance according to indoor and outdoor temperature in operation process. On the other hand, stronger solar radiation in summer makes the heat into the room increase, which needs complex air conditioning system powered by the fossil energy to adjust the indoor environment. Overcoming the shortcomings of traditional building envelope, especially us ing solar energy to realize the aim of actively controlling the heat flux of wall in summer, eliminating heat gain from the source and providing a certain cooling capacity for indoor room, and utilizing renewable energy air conditioning system to control indoor environment have important significance for building energy saving.The main purpose of this paper is to propose a self-adaptive wall. Employing thermodynamic analysis, combining simulation computation and experimental method, the performance of the self-adaptive wall using solar energy to control the wall heat flux and provide cooling(heat) capacity for indoor room was studied. A suit of dynamic model, the basic calculation and analysis method of the self-adaptive wall system were presented, which provides a theoretical basis for re al-time understanding and controlling of self-adaptive wall system and its economic and feasibility analysis. Meanwhile, a novel solar thermoelectric air conditioner system was developed, which provides a new method for solar energy air conditioning system application in buildings, as well as a new way of building energy saving. The main research works are as follows:Firstly, a thermodynamic model of thermoelectric cooling system was developed. Reasonable system structure parameters and operating condition s are the key factors to improve the performance of thermoelectric cooling system. Based on the thermodynamic model, the system performance under different temperatures of heat mediums, working current, total heat sink area and the allocation ratio of heat sink area and other parameters were analyzed and optimized. Moreover, the range of work current for thermoelectric cooling system using in buildings was provided based on the thermodynamic analysis. Based on the optimal operating current of TE modules and the analysis based upon PV modeling theories, the connections for the TE modules in solar thermoelectric cooling system was optimized, and a method for coupling the thermoelectric system with PV system was developed for system design and operation.Secondly, a novel self-adaptive wall was developed. A self-adaptive wall test platform was built and a large number of experimental was made to test its performance. The experimental showed that the self-adaptive wall cannot only eliminate conventional building envelop thermal loads but also provide a certain cooling capacity or heating capacity for indoor room at the same time. The stronger the solar radiation is, the lower the surface temperature of the wall and the greater the amount of cooling capacity will be. When the installation angle was 60 degree and the solar radiation is above 450 W/m~2, the cooling capacity of the self-adaptive wall is 40W/m~2 to 70 W/m~2. In winter, the solar energy can be used to heat indoor room. The stronger the solar radiation is, the higher the surface temperature of the wall and the greater the amount of heating capacity will be. When the Photovoltaic cells installed 90 degrees and the cooling channel is closed, the solar radiation intensity is at 357 W/m~2 to 660 W/m~2, the heating capacity of the wall is about 128 W/m~2 to 167W/m~2.Thirdly, a self-adaptive wall model was established and verified by experimental data. Then, the insulation material thickness, vent size and cooling channel size were analyzed and optimized by the self-adaptive wall model, respectively. In addition, the impact of the indoor temperature on the performance of self-adaptive wall was analyzed. The self-adaptive wall’s performance in Wulumuqi, Beijing, Changsha and Guangzhou under the worst operationg condition(when the PV’s installation angle is 90 degree) was simulated. The results showed that the performance of the self-adaptive wall is the best when the wall is east under cooling mode in summer. The cooling capacity provided by the east wall from June to August is 45.98 k Wh/m~2 and 22.61 k Wh/m~2 in Wulumuqi and Beijin, and the solar energy utilization efficiency is 8.61% and 5.41%, respectively. And the cooling capactiye is 25.39 k Wh/m~2 and 16.36 k Wh/m~2 in Changsha and Guangzhou from June to september, and the solar energy utilization efficiency is 5.1% and 3.79%, respectively. Economic analysis of self-adaptive wall application in Wulumuqi, Beijin, Changsha and Guangzhou were conducted, the results showed that investment recovery period of self-adaptive wall application in Wulumuqi, Beijin, Changsha and Guangzhou were 9.6 years, 8.4 years,13.9 years and 13.3 years, respectively.Finally, a solar thermoelectric air conditioning system was proposed and tested. The system can work in the following three operating modes: space cooling and water heating mode, space cooling mode and space heating mode. The mode of the solar thermoelectric air conditioner was established and verified by experimental data. The experiment and simulation results showed that the solar the rmoelectric air conditioning system had obvious energy saving effect in space cooling and water heating mode, and the system could obtain higher cooling and heating efficiency by controlling the input working current and the cooling water temperature.The self-adaptive wall studied in this paper cannot only eliminate conventional building envelop thermal loads but also provide a certain cooling or heating capacity for indoor room at the same time. The self-adaptive wall presents fundamental shift from building enveop energy saving by optimizing the insulation thickness to a new regime where active solar building envelop is designed to increase the performance of heat insulate in all seasons. And utilizing solar energy air conditioning system to control indoor environment, which can overcome the fault of traditional air conditioning system powered by fossil energy and have important significance for building energy saving.