Research On The Performance Of A Novel Building Integrated Photovoltaic-thermal Module And System

With the continuous growth of China’s energy consumption,the problem of energy shortage and environmental pollution has become increasingly serious.The use of clean energy and the development and promotion of renewable energy utilization technologies are of great significance.Solar energy has gained widespread attention in the utilization of renewable energy due to its advantages of wide distribution,easy access,clean and pollution-free.Building energy consumption accounts for a large proportion of the total energy consumption in our society and has great energy-saving potential.The combination of solar energy and buildings is an ideal way of using solar energy,which can provide users with heat and electricity without occupying additional area.In this thesis,a new type of photovoltaic/thermal(PV/T)module is proposed.By means of numerical simulation,the effects of the size of the collector tube,the thickness of the collector plate,and the spacing of the collector tubes on the heat transfer performance of the module are studied to determine the optimal structural parameters of PV/T module.Taking a two-story building in Shanghai as an example,the PV/T modules are integrated on the roof to build a building integrated photovoltaic/thermal(BIPV/T)system with a composite air source heat pump,and the air source heat pump system is used as a reference system.Using TRNSYS simulation to study the performance of two systems and make a comparative analysis to discuss the energy saving and economy of BIPV/T system.First of all,based on the typical structure of water-cooled PV/T module,this thesis designs a new type of PV/T module that uses a capillary network to cool photovoltaic panels,and a reasonable model is established and verified.Taking PV/T module thermal efficiency,average outlet water temperature,average photovoltaic panel temperature,heat flux density,etc.as evaluation indexes,the influence of cooling channel structure parameters on the heat exchange performance of the module is studied.The results show that the size of the collector tube has little effect on the heat transfer performance of the PV/T module,and the thermal efficiency of the module is slightly improved at a small tube diameter;the thickness of the collector plate has basically no effect on the heat transfer performance of the PV/T module;The heat exchange performance of the PV/T component is significantly affected by the spacing of collector tubes.The smaller the spacing of the collector tubes,the better the heat exchange performance.The optimal structural parameters of the new PV/T module are as follows: the size of the collector tube is 3.4 × 0.55 mm,the thickness of the collector plate is 0.3mm,and the spacing of the collector tubes is 10 mm.Compared with the reference PV/T module that uses copper tube heat collection,the thermal efficiency gap between them is small.Considering factors such as thermal efficiency,weight,cost,and environmental benefits,it is feasible for capillary tube to replace the PV/T module using copper tube to collect heat.Then,taking a two-story house in Shanghai as an example,the load calculation was performed using typical meteorological year data,and the feasibility of solar energy utilization is obtained based on the analysis of building load characteristics and solar resource.Combining the new PV/T module with the roof,a BIPV/T system using an air source heat pump as the auxiliary cooling and heating source is designed.The system has the functions of cooling in summer,heating in winter,generating electricity throughout the year,and providing domestic hot water.Using the air source heat pump system as a reference system,the operating modes and system control strategies of the two systems in different seasons are proposed.A system simulation model is built in TRNSYS software and the design parameters of each component are determined.Finally,the BIPV/T system and the air source heat pump system under typical weather conditions throughout the year and the system performance are simulated and analyzed.The system operating characteristics under different system forms are compared.The results show that building integrated PV/T modules can reduce the heating load of the building heating and increase the cooling load of the building air conditioner.In general,compared with the reference system,the BIPV/T system reduces energy consumption for heating/cooling of buildings and domestic hot water.The annual power generation of BIPV/T system is greater than the total energy consumption of the building.When guaranteeing the energy consumption of cooling,heating and domestic hot water in the building,the system can realize 6235.2k Wh of electricity revenue throughout the year.The economic analysis of the system shows that the dynamic additional investment recovery period of the BIPV/T system is 12.6 years,which is lower than the life of the system,and the system has better energy saving and economic efficiency.