Numerical investigation of the effects of heating and contact conditions on the thermal charging performance of composite phase change material

Abstract

Abstract Phase change material (PCM) saturated in metal foam is a promising candidate for thermal energy storage (TES). However, there are some potential factors affecting the thermal charging performance of composite PCM, such as heating and contact conditions. In this paper, paraffin and copper foam are selected as PCM and metal matrix, respectively. Heating conditions are top, left and bottom heating. The contact gaps are set to 0, 0.4 and 0.8 mm to represent different contact conditions. The numerical investigation on thermal charging performance of composite PCM under different heating and contact conditions is performed. Based on volume-averaged method, the numerical model is developed to study the thermal characteristics of composite PCM including solid-liquid interface, liquid fraction, velocity, total melting time and average heat storage rate. Results show that there are the comprehensive effects of heating and contact conditions on thermal performance. The heating condition can affect phase change heat transfer mode, and thus has a significant influence on thermal charging performance. The contact conditions have the different effects on thermal behavior of composite under different heating conditions, e.g., under top heating condition, the total melting time of composite with 0 mm and 0.8 mm contact gaps is almost the same. Whereas, under left heating condition, the total melting time of composite with 0.8 mm contact gap is 2.6 times that of composite with 0 mm contact gap. The study of the effect mechanism of heating and contact conditions is of great significance for practical application of composite PCM in TES system.