PCMs Heat Transfer Performance Enhancement with Expanded Graphite and its Thermal Stability

Abstract

This work focuses on developing a high performance phase change materials (PCMs) adding with a few expanded graphite (EG). A series of composite phase change materials (paraffin) with various EG concentration are formulated in vacuum condition and ambient pressure respectively. The heat fusion of composite PCMs is measured by DSC. A rig for PCMs heat transfer performance test is built in lab. The heat transfer performance test of composites PCMs are carried out. The heat storage and release processed of pure PCMs and composite significantly improved after EG adding. The composited PCMs formulated in vacuum condition also presents better heat transfer performance. It shows composite PCMs can be well mixed in vacuum. Due to the repeated heating and cooling in PCMs application, thermal stability test is carried out in this work. PCMs are putting in water bath with temperature controlling by cyclic phase change to quantify the rate of degradation heat fusion and thermal charge/discharge process. After cycling 60 times, up to 2% heat fusion decrement is observed. Heat transfer performance studies also show that there is little change. In brief, PCMs with EG has high thermal performance for thermal energy storage process.