Numerical study on energy and exergy performances of a microencapsulated phase change material slurry based photovoltaic/thermal module

Microencapsulated phase change material (MPCM) slurry has proven to have potential in elevating the overall performance of a photovoltaic/thermal (PV/T) module as a working fluid. In order to make full use of the superiority of MPCM slurry and further improve energy and exergy efficiencies of the PV/T module, the effects of MPCM concentration and melting temperature under a wide inlet fluid velocity range were explored based on a three-dimensional numerical model of coupled heat transfer in this study. The results show that both the energy and exergy efficiencies increased with the concentration. A lower melting temperature resulted in higher energy efficiency, whereas a higher melting temperature is helpful for exergy efficiency improvement. The slurry with an excessively low melting temperature (e.g. 27 degrees C) even led to lower exergy efficiency than pure water. The melting temperature needs to be precisely tailored to make a compromise between energy and exergy efficiencies. In comparison with pure water, the improvement in energy efficiency provided by the slurry was further enhanced at a lower inlet velocity, while the improvement in exergy efficiency was optimized by adjusting the inlet velocity to a certain value. The maximum improvement in energy efficiency provided by the slurry was 8.3%, whilst that in exergy efficiency was 3.23% in this work. From the above, the superiority of MPCM slurry can be further promoted by selecting suitable material properties and operating parameters.