Experimental study on the thermal performance of air-PCM unit

Abstract

In the present research paper thermal performance of an air-phase change material (PCM) unit has been experimentally studied. The influences of the air inlet temperatures and velocities have been investigated on the charging/discharging time of the PCM panels, heating/cooling load and effectiveness over the phase transition. These parameters play a vital on determining thermal performance of an air-PCM unit. Air inlet temperatures of 34 °C, 36 °C and 38 °C and air inlet velocities of 0.6 m/s, 1.6 m/s and 2.5 m/s. have been studied. The increase of the air inlet velocity reduced the charging and discharging time, however not linearly. The time for the complete melting and solidification is substantially reduced when the velocity has been increased from 0.6 m/s to 1.6 m/s. The air inlet temperature has been proved to be most important factor affecting the discharging time. For lower air inlet velocity the cooling and heating loads achieve lower values but remain nearly constant over a longer period of time. The effectiveness reaches its highest values for the air inlet velocity of 0.6 m/s for the charging and discharging processes. It has been concluded that discharging time can be extended by reducing the air inlet velocity and making the technology more suitable for heating and cooling applications for the buildings. A simplified methodology is proposed for the analysis of the PCM charging and discharging process through the identification of the critical points as result of the heat transfer behaviour in the air- PCM unit.