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 °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.