Enhancements of heat transfer and thermoelectric performances using finned heat-pipe array

Phase change materials (PCMs) are highly promising for heat storage and passive cooling due to the combined advantages of high latent heat and selectable phase-change temperature, whereas suffer from the defect of low thermal conductivity. However, limited improvement of thermal conductivity of phase change materials (PCMs) by flat fins has severely restricted the cooling and latent heat release rates of PCMs. Moreover, previous literature has seldomly focused on the application of exhausted heat or PCM-stored latent heat. Confronted with above issues, we experimentally demonstrated a new enhancement regime for both phase-change heat transfer and thermoelectric power using PCM embedded with heat-pipe (HP) array instead of traditional fins. Results indicated that adding HP array significantly enhanced the phase-change of PCM with the wall temperature reduced by 51 degrees C compared with pure PCM. Moreover, the maximum vertical and horizontal temperature gradients were less than 1.5 degrees C and 2.5 degrees C due to the small thermal resistance of HPs. TEG power with single HP was nearly four times higher than that with three HPs, whereas at the expense of 20 degrees C increment in wall temperature. PCM convection contributed 20 degrees C of wall temperature drop, but reduced the thermoelectric power.

Automated summary

Phase change materials (PCMs) are promising for heat storage and passive cooling due to their high latent heat and selectable phase-change temperature, but suffer from low thermal conductivity. In this study, a new enhancement regime for phase-change heat transfer and thermoelectric power was demonstrated by using PCM embedded with heat-pipe (HP) array. Results showed that adding HP array significantly enhanced the phase-change of PCM and reduced the wall temperature by 51°C compared to pure PCM. The small thermal resistance of HPs resulted in temperature gradients of less than 1.5°C and 2.5°C in the vertical and horizontal directions, respectively. While the thermoelectric power was nearly four times higher with a single HP compared to three HPs, the wall temperature increased by 20°C. PCM convection contributed to a 20°C decrease in wall temperature but reduced the thermoelectric power.