| Photovoltaic/thermal (PV/T) utilization technology is the combination of photovoltaic modules and solar collectors, which can convert the solar energy into electrical energy and take heat away from the photovoltaic panels to be used, while generating electricity and heat two energy gains. At present, water is widely used in domestic and abroad as heat carrier fluid,but with the deepening of research and the continuous improvement of performance, the performance of solar PV/T collector based on water has been restricted greatly. According measures bring the investment is getting higher and higher.At the same time, phase change materials are widely used in the field of thermal energy storage and utilization because of their high thermal storage density and wide temperature range. Latent heat function of heat fluid, also known as phase change slurry (PCS), is a Multi-phase heat fluid which the phase change material labeled nanometer-sized particles or wrapped in the form of capsule dispersed in the heat transfer fluid to improve the heat transfer efficiency. The appearance of PCS solves the problem of low heat transfer efficiency when phase change material is directly used as heat transfer medium. PCS has a broad prospect in the heat storage, industrial waste heat recovery and other fields.In this paper, we combine solar PV/T collector system with phase change slurry organically, use phase change slurry instead of the original collector system of water medium,lead to the system of sensible heat storage into sensible heat and latent heat storage mode to enhance thermal efficiency, electrical efficiency and comprehensive efficiency. In this paper,the type of phase change slurry and the phase change temperature were determined by considering results of the papers and demands for the use. The properties of the phase change slurry with different types and different mass fractions were tested, including thermal properties experiment, fluidity experiment and stability experiment. On the basis of physical property test, the phase change slurry with the best performance is selected. Secondly, two sets of solar PV/T collector system were set up and the deviation rate of the two systems was verified by water, the measurement items and evaluation indexes were determined. Finally,the selected phase-change slurry and the water medium system are operated under the same operating condition; the performance of the system is evaluated by the same evaluation index.It provides the foundation and support for the application of the phase change fluid to the engineering practice.The main conclusions of the paper are listed as follows:? 30% alkyl hydrocarbon PCS was selected for PV/T solar collector system according to thermal properties experiment,fluidity experiment and stability experiment; ? We selected radiation intensity, temperature,flow, photovoltaic panel output current/voltage and system pressure loss as testing measurements; Medium temperature in collector, water temperature in the heat transfer tank,surface temperature of the PV panel, thermal/electrical power, thermal/electrical efficiency,total energy income, the comprehensive efficiency as well as the system resistance loss and so on ten indexes take the system performance appraisal target. The two systems' deviations of the indexes are within ± 16%.?The performance of the PV/T system based on the phase change slurry is superior to that of the water system under the same test conditions. The thermal efficiency of the PV/T system is the highest, 40.5% higher than that of the water system.The research results of this subject provide the foundation and experimental support for the performance of phase change fluid and its application in engineering practice. It has certain reference significance for the research of phase change fluid in solar energy storage field. |
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