Energy Reduction of the Air-Conditioner by Using a Packed Ball of Phase Change Storage

        In this study, a new concept of using phase change material (PCM) for improving cooling efficiency of an air-conditioner by installing at an evaporator and a condenser have been presented under Thai climate. Rubitherm20 (RT-20) is selected to evaluate the thermal performance by reducing the air temperature entering the air-conditioner. The model of PCM celluloid balls have been performed with the air-conditioner to verify with the testing results. For the experiment, 2 TR of R-134a air-conditioner is chosen to test a packed bed of PCM balls with thickness 40 cm. The pressure drops of the air flowing through the bed are considered with and without a set of by-pass tubes along the height of the storage bed. From the study results, it could be seen that pressure drops of the bed with and without bypass tubes were nearly the same results. Thus, PCM ball packed bed using RT-20 without bypass tubes was used to improve the cooling efficiency of air-conditioner at the evaporator and the condenser, respectively. The testing results also shown that the simulated data of the PCM temperature and the air leaving PCM bed temperature agreed quite well with the experimental results at the discrepant around 2.73% and 4.61%, respectively. The economic results found that the electrical power consumption of the modified air-conditioner decreased 3.09 kWh/d and 1.71 kWh/d in cases of installing at the evaporator and the condenser, respectively. Moreover, the saving costs of the modified systems at the evaporator and the condenser could be 8.87% and 5.76% at the payback period were 4.27 y and 6.55 y, respectively.

Keywords: Air-conditioner, Phase change material, Rubitherm20, Thermal energy storage, Thermal performance