Low-temperature macro-encapsulated phase change material based thermal energy storage system without air void space design

Highlights: • Eliminate air void and give good heat transfer between PCM and housing by dampeners. • Results show air void in macro-encapsulation affects heat transfer performance. • Thermal cyclic tests show stable performance up to 50 cycles for real applications. A robust macro-encapsulation design of a low-temperature phase change material based thermal energy storage unit is presented. The developed macro-encapsulation container eliminates the need for the 20% air void space catered for the volumetric expansion of the phase change material during melting in conventional designs. A study was conducted to validate the effectiveness of the design on thermal conductivity with volumetric expansion on a 2-dimensional axis symmetrical model. The results from the numerical and experimental approaches came to a good agreement that heat transfer has improved. The thermal robustness of the proposed design was successfully demonstrated after multiple thermal cycles on the design.