Discharging performance enhancement of a phase change material based thermal energy storage device for transport air-conditioning applications

A compact thermal energy storage device containing a phase change material has been designed and experimentally investigated for smoothing cooling load of transport air conditioning systems. The phase change material based device used two different types of fins, serrated fins in the air side and perforated straight fins in the phase change material side, for enhancing the device performance. The focus of the work was on the discharging process of the compact device, which is more important for transportation applications. An experimental rig was designed and constructed for measuring the discharging behaviour of the device. The processing of the measurement data gave the discharging time, discharging depth, discharging power, accumulated discharging energy, thermal efficiency and exergy efficiency under different inlet air temperatures and velocities over the working period defined on the basis of the cooling requirement. The results show a fast response with the hot air flow cooled down to the desired temperature range of 16-20 degrees C in seconds. The thermal energy storage device showed a high thermal and exergy efficiency at 99.8% and 43.3%, respectively. The discharging depth was higher than 97%, indicating good heat transfer performance of the device. The PCM based device also showed flexibility for adjusting the output cooling capacity, leading to a great potential to resolving frequent fluctuations of cooling loads of transport air conditioning systems.