Enhancement of heat transfer of microcapsulated particles using copper particles and copper foam
Zhonghao Rao*, Yiping Wen, Chenzhen Liu
The application of phase-change materials (PCM) for thermal-energy storage is hampered by their low thermal conductivity. Copper particles (CP) and copper foam (CF) were used to enhance the thermal conductivity of a microencapsulated phase-change material (MicroPCM). The effects of the CP size and mass fraction and the pore number per inch (PPI) of the CF on the thermal properties of the MicroPCM were investigated. The chemical and microstructures of the MicroPCM and its CP composites were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. Their thermal conductivities, phase-change temperatures, and latent heats were measured. Adding CP into the MicroPCM decreased the latent heats with increasing loadings. The thermal conductivities of MicroPCM/CP (5 wt%, 50 nm diameter) and MicroPCM/CF (PPI 30) were 1.12 times and 3.46 times that of the unmodified MicroPCM at 20 °C, respectively. Thermal-energy storage performances of the MicroPCM/CF composites were studied at a power of 2.9 ± 0.1 W. The temperature of the contact surfaces of the pure MicroPCM and its composites (PPI 10, PPI 20, PPI 30) was 75.88, 51.27, 50.52, and 50.23 °C, respectively. The composites displayed more uniform temperature distributions.
Microencapsulated phase-change material; Copper particles; Copper foam; Thermal conductivity; Thermal energy storage