Thermal performance enhancement of phase change material heat sinks for thermal management of electronic devices under constant and intermittent power loads

•Effects of PCM filling ratio, intermittent power load and heat transfer coefficient are discussed.•The negative and positive effects of PCM are assessed.•PCM heat sink is more effective approach under intermittent power load.•PCM heat sink with 30% PCM filling ratio has the best performance. Metal fin enhanced phase change material (PCM) has been successfully demonstrated as an effective approach for electronic devices cooling, especially in the case of high-power density for only a limited period. Application of PCMs in the heat sink accelerates the heat storage and reduces the heat rejection resulting in a tradeoff effect. In this study, the effects of PCM filling ratio, intermittent power load with different power off time interval and heat transfer coefficient on the performance of PCM-filled heat sinks are studied for electronic devices cooling. A constant power load is firstly studied to reveal the effect of PCM filling ratio. An intermittent power load with different power off time interval is then investigated to enlarge the operation time of electronic devices. Finally, the effect of heat transfer coefficient is discussed to assess the negative and positive effects of PCM. The results show that the effective operation time of PCM-filled heat sinks significantly increases and its peak temperature obviously reduces under intermittent power load compared to the constant power load, and it becomes more apparent with increasing power off time interval. The thermal performance of PCM-filled heat sinks significantly strengthens under natural cooling condition, i.e., h = 10 or 20 w•m−2•K−1. However, during forced convection cooling, e.g., h = 100 w•m−2•K−1, the heat sink without PCM may have a better performance because the negative effect of PCM outweighs its positive effect. The results of this paper are of great significance in the optimal design of PCM-filled heat sink.