Availability (exergy) analysis in a thermal energy storage system with the phase change materials arranged in series

In this article, a thermal energy storage system is studied from the irreversibility point of view. The system consists of some phase change materials arranged in series. The phase change materials are located in the annular space between two concentric cylinders while the working fluid is flowing in the inner cylinder. Charging and discharging processes occur periodically. The conservation equations of energy for the working fluid and the phase change materials are solved numerically. The numerical results are validated when compared with available experimental results. The effect of different physical and geometrical factors on the irreversibility of the system is studied. The results show that the number of phase change materials and their arrangement have great influence on the irreversibility of the system. The temperature distribution inside the phase change materials affects the availability of the system. The proper arrangement of the phase change materials can reduce the irreversibility or increase the availability of the system.