| The ever-increasing energy crisis and building energy consumption have made building energy conservation become the focus of the governments.The fresh air system helps improve indoor air quality while brings the buildings 20-40%energy consumption of the overall air conditioning systems.Therefore,the research and development of novel building fresh air equipment,the comprehensive use of solar energy and exhaust heat recovery technology to reduce the energy consumption of building fresh air are of great significance to building energy conservation.Photovoltaic thermal-compound thermoelectric ventilator(PVT-TEV)system uses electricity generated by photovoltaic(PV)cells to drive thermoelectric ventilator(TEV)system,which utilizes PV cells to generate electricity while preheating the fresh air and recovering exhaust heat actively.In this paper,the PVT-TEV system was studied comprehensively.The mathematical model of the PVT-TEV system was established and verified.Based on this,the system parameters were optimized and the performance of the system under different climate regions was simulated.The main contents and results are as follows:Firstly,the PVT system’s electrical circuit model was established and the I-U characteristic curve of the PV cells was obtained.On the basis of control-volume method and zonal approach,the dynamic heat transfer model of the PVT system was established and the finite difference method was used to calculate the mathematical model.Heat transfer analysis and modeling were performed on the TEV system.Then,the three models were coupled to establish the numerical model of the PVT-TEV system.Secondly,experimental data were used to verify the accuracy of the PVT-TEV numerical model.A PVT-TEV system test platform was built in Changsha to test the power generation and heat transfer performance of the system under winter conditions.The results show that the simulated data show good agreement with the experimental values,and the numerical model of the PVT-TEV system has good accuracy.Thirdly,the sensitivity analysis of the system parameters was conducted using the established model.The PVT-TEV system performance was simulated for different fresh air volume flow rate,working current and indoor temperature.The results show that increasing the fresh air volume flow rate can improve the thermal and electrical performance of the PVT-TEV system.The fresh air heat gain and supply temperature of the TEV system increase and the total coefficient of performance(COP)decreases with the growth of the working current.The higher the indoor temperature is,the greater the total heat gain and total COP of the system.Finally,the energy-saving potential of the PVT-TEV system under different climate regions in China was analyzed using the established numerical model.The results show that the average solar energy efficiency in Lhasa is the highest,followed by Shenyang and Beijing.Due to the high ambient temperature and the lack of sunshine,Changsha has the lowest solar energy efficiency.In addition,this paper also analyzed the influence of working current on the performance of PVT-TEV system in different climate regions which provides reference for current selection when the system is applied in different regions.Handling fresh air by comprehensively utilizing solar energy and building waste heat,PVT-TEV system can obtain higher solar energy efficiency and heating coefficient.The results can provide a guidance for the structural design and optimization of the PVT-TEV system,and the application of the PVT-TEV system in different climate regions. |
