Theoretical and Experimental Study of a Novel PV-Trombe Wall System

Building integrated photovoltaic/thermal (BIPV/T) is a new concept of providing both electricity and heating by setting fluid duct to re-capture and re-use the waste heat energy removed by fluid flow, after paving PV modules on building envelop or replacing it. Due to the shortage of energy supply and the fast increment of building energy consumption, BIPV/T can lead to a large scale development of renewable energy and decrease of the dependence on conventional energy, since it improves the overall efficiency of utilizing solar energy.Since the original Trombe wall is single-functional and unaesthetic, a novel concept of BIPV/T, i.e. PV-Trombe wall (short for "PV-TW") is presented in this thesis bases on the idea above. It is constructed by affixing PV cells back of the glass panel. It not only provides space heating in winter and reduces indoor cooling load in summer while generating electricity, bust also improves the visual comfort of building envelop and makes buildings more eye-catching.In this thesis, the PV glass panel of PV-TW is designed and manufactured by laminating PV cells and glass panel together. Then a fielding testing rig is constructed by installing PV-TW on a comparable hot-box. After that, the thermal and electrical performance of PV-TW system for winter heating in 8 different cases are tested according to comparable experiments for PV-TW system with/without window, with/without heat storage, with/without DC fan, with/without periodically operating air vents, and the electricity and temperature data are recorded for performance analysis.Furthermore, the PV-TW and indoor room are innovatively coupled together as a PV-TW system. After establishing the unsteady heat transfer and dynamic model for every part of PV-TW system, the temperature field, electrical performance and heat gain component are numerically calculated when PV-TW system operates in different seasons. Based on the simulation results, the effect of the PV-TW’s width and area of air vents on system’s performance are investigated, and the performance of improved systems are analyzed after introducing two improvements, i.e. thermal insulation of the collector wall and curtain installation. For the case of PV-TW system without window-without heat storage-with/without DC fan-with periodically operating air vents and that with window-with heat storage-without DC fan-with periodically operating air vents, the system’s model is improved and expanded, and then the simulation results are compared with experimental results to validate the new model, while the effect of DC fan and window on system’s performance are further studied. In order to apply PV-TW on Tibetan typical residential buildings, the system’s model is further expanded and the effects of PV-TW’s width and thermal insulation of building envelop on system’s performance are researched. Consequently, an appropriate width is chosen according to standards of winter heating and the performance of PV-TW system applied in Tibet is detailedly analyzed.The theoretical and experimental results indicate that the PV-TW system can improve indoor temperature obviously, and the maximum temperature difference between rooms with and without PV-TW can reach more than 20°C while the electrical efficiency is about 10-11%. When PV-TW system operates in winter, both thermal insulation of the collector wall and building envelop help further improving the indoor temperature, but the electrical efficiency is decreased a little. In addition, DC fan is advantageous for both thermal and electrical performance, while heat storage and periodically operating air vents help further improving indoor comfort. When PV-TW system operates in summer, thermal insulation of the collector wall and curtain installation must be carried out to decrease indoor temperature, even only a little. The operating temperature of PV cells is about 30～50°C, which indicates that PV-TW can cool PV cells effectively in summer. However, thermal insulation of the collector wall still restrains PV cells’ cooling while curtain installation can improve electrical efficiency a little. The parametric study of PV-TW shows that the indoor temperature increases along with the increase of PV-TW’s width and area of air vents. The relation between PV-TW’s width and indoor temperature is nearly linear so that an appropriate width should be chosen according to design requirement. However, the indoor temperature is almost constant when the ratio between the area of air vents and the cross sectional area normal to the height direction of air duct is greater than 0.7 so that a value of 0.5～0.7 is recommended.