| With the improvement of human life quality,people's demand for indoor thermal environment is higher and higher.As a result,the energy consumption of heating,ventilation and air conditioning is increasing in the building energy consumption.The development and application of renewable energy,such as the combination of solar energy application technology and buildings,is an important way to save energy and reduce building energy consumption.The combination of solar photovoltaic power generation technology and Trombe wall system(PVTW)is a kind of solar energy efficient utilization technology that has been rapidly developed under the situation of energy saving,emission reduction and development of renewable energy.The PVTW system combines the advantages of the traditional Trombe wall system with the advantages of photovoltaic power generation technology,which not only solves the single function of the traditional Trombe wall system,poor insulation,but also solves the problems of high temperature of PV cells and low electrical efficiency.The PVTW system solves many current difficult problems and improves the comprehensive utilization of solar energy.In this paper,the crystalline silicon solar cell and the low-iron tempered glass or the thin metal aluminum plate are respectively laminated into a solar cell module through an adhesive.Because of the glass-laminated PV cells module is installed in the outer of Trombe wall system,and this system known as built-out photovoltaic integrated Trombe wall(PVOTW).The PVOTW system has the advantages of good heat dissipation environment and high electrical efficiency,but it has the disadvantages of poor thermal insulation,insufficient heat supply in winter and low room temperature.The other type is the PV cells was installed on the interior massive wall surface of Trombe wall,which was called as built-in photovoltaic integrated Trombe wall(PVITW).This structural design can improve the thermal performance of the PVITW system,but it is not conductive to cooling of PV cells attached on the massive wall,which results in lower electrical efficiency.In addition,due to the the shadow formed from the system frame on the surface of the PV cells has a certain influence on the electrical performance;furthermore,dust-laden air continuously flowing through the PV cells surface will form dust on the surface of the PV cells,which will affect the power generation.To improve the thermal performance of the PVOTW system and the electrical performance of the PVITW system,it is proposed to place the solar cell module laminated with the thin metal aluminum plate in the air flow.Which is called as built-middle photovoltaic integrated Trombe wall(PVMTW).The PVMTW system not only takes into account the thermal insulation performance but also improves the electrical performance.The main research work of this paper includes:(1)The experimental platforms of the PVOTW system and the PVITW system are developed and built.In order to investigate the thermal and electrical properties of the two kinds PVTW systems,we carried out experimental tests in winter and summer.The results show that the PVOTW system has a power generation efficiency of 1.7 times that of PVITW system during summer operation,and the temperature in the room with the PVITW system is higher than that in the room with PVOTW system.The average thenmal efficiency of the PVITW system and the PVOTW system are 0.328 and 0.293 respectively.In terms of electrical performance,under the same environmental temperature and irradiation,the electrical efficiency of the PVOTW system is 0.142.while PVITW system is only 0.105,the former is 1.35 times higher than the latter.However,for the comprehensive utilization of solar energy,the PVOTW system has an advantage over PVITW,which is 4.81%higher than the PVITW system.Therefore,we removed the PVITW experimental platfomi for the construction of a platform of the PVITW system.(2)The experimental platform of PVMTW system is built in the original PVITW site,and the winter experiment of PVMTW system is carried out.The thermal and electrical properties of the PVMTW system are analyzed through experimental data,and the feasibility of this new structural system is quantitatively evaluated by data compared with the PVOTW system.The results show that the average thermal efficiency of PVMTW system is 0.396,which is 1.35 times of that of PVOTW system,and the power generation efficiency is 18.9%lower than that of PVOTW system.However,from the perspective of comprehensive utilization of solar energy,the effective utilization ratio of PVMTW system to solar energy is 10.8%higher than that of PVOTW system.(3)The dynamic thermal and electrical model of the PVMTW system in the vents on/off mode is established.The experimental data is used to validate the model of the PVMTW system.Using the validated model,the height of the airflow channel,the PV cells ratio,and the effect of the thickness of the air layer between the glass and the solar panel on system performance are analyzed.According to the results of the parameter analysis,the structure of the PVMTW system is theoretically optimized.Through numerical simulation,the thermal performance of the PVMTW system is evaluated by comparing the opening/closing time of the vent,the air temperature in the room,the surface temperature on the interior wall and the thermal comfort of the room with the traditional Trombe wall without PV cells.The simulation results show that with the increase of the height of the air channel,the heat gain increases significantly,while the electrical efficiency decreases.When the channel height exceeds 2 m,the increase in thermal efficiency is weakened.Due to the high limitations of the building,the difficulty of product processing and installation conditions,the height of the air channel is set to be around 2 m.When the PV cells coverage increased from 0.2 to 1.0,the power generation increased by nearly 5 times,and the thermal efficiency decreases by 24.9%.Therefore,the change in the coverage of the PV cells has a significant effect on the thermal efficiency.In the case of keeping the distance between the glass cover and the massive wall constant(0.12 m),as the thickness of the air layer(between the glass cover and the PV panel)increases,the electrical efficiency is less affected.The thermal efficiency and total efficiency first increase and then decrease.The result implies that the air layer is in the range of 12 mm-30 mm,the total efficiency achieves a maximum of about 0.573.Furthermore,the simulation results also show that the vents of PVMTW system can be set at 8:00/17:00 under the meteorological conditions corresponding to the experiment;the average air temperature in the room with the PVMTW system is only 0.2? lower compared to that with the classic Trombe wall system;in the day,the air temperature in the room is basically kept above 18?;the room with the PVMTW system achieved a PMV(the average predicted mean vote)of 0.05,which made the indoor thermal comfort approach neutral,while the PMV of the classic Trombe wall system was-0.36,and the room was a little cold. |
PDF Full Text Request