Summary: | In order to meet energy conservation targets and minimize global warming effects, this research is aimed to rise the efficiency of the PV/T system. This research investigates the usage of microencapsulated phase change slurry (MPCM-S) to replace conventional cooling fluids such as water. The phase change materials (PCMs) are encapsulated in a polymer shell forming microencapsulated phase change materials (MPCM) to prevent leakage of the PCMs as well as increasing the thermal conductivity. Mixtures of (5%, 10% and 15%) of microencapsulated phase change materials in water (slurries) were investigated. The use of phase change materials (PCM) improves heat absorption from the PV module due to their high latent heat, consequently increasing thermal output of the system, and electrical output because the PV panel temperature is reduced. The research started with an intensive literature review covering all elements involved, and then the conceptual design of the experimental rig was developed. Theoretical investigations including a steady-state computerized simulation module were developed, this simulation validated depending on a previous research and showed good agreement with results from that published experimental study. This suggested that the computer module could successfully predict the operational performance of the module with satisfactory accuracy. A series of laboratory-based tests were conducted for a wide range of conditions and slurry concentrations. The results were compared to the computer simulation with the same parameters. It was found that the root mean square percentage deviations (RMSPE) between experimental and simulated results were generally under 4%, so considered acceptable for engineering application of PV/T system. A slurry concentration of 10% was found to give the best results. Under operational conditions of 10% MPCM concentration, 3000 Reynolds number and 600W/m2 solar radiation, an experimental test was conducted. The electricity and heat outputs of the system were 108 and 520 W respectively, the associated electrical and thermal efficiency were 14.1% and 68.8%, giving an overall efficiency of 82.9%. The economic analysis was carried out to investigate the feasibility of the MPCM-S based PV/T system in two different climates of Europe. It showed that the system generates higher annual electrical and heat of 488.29 and 2184.93 kWh in a hot climate (using Madrid as an example) than the annual electrical and heat of 323.12 and 1262.1 kWh for colder climate (Stockholm as an example). Consequently, the life cycle cost of MPCM-S based system per kWh were -0.068 and 0.019 GBP for Madrid and Stockholm respectively, and for water-based PV/T system were -0.038 and 0.028 GBP for Madrid and Stockholm respectively. Finally, the environmental effect of the system was investigated by calculating the life cycle CO2 emission reduction of MPCM-S based PV/T system in both climates, they were 11.75 and 6.9 tonnes for Madrid and Stockholm respectively, and for water-based PV/T system were 7 and 3.5 tonnes for Madrid and Stockholm respectively. Generally, the MPCM-S based PV/T system is more efficient than the conventional water-based PV/T systems as predicted, especially if it runs with 10% MPCM-S. It delivers higher electrical and heat outputs in hot climates in comparison with colder climates of Europe, consequently better economically and environmentally.
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