Evaluation of cooling ability for a novel heat sink made of polyvinyl alcohol hydrogel

A novel material-integrated heat sink made entirely of polyvinyl alcohol (PVA) hydrogel has been investigated for understanding the technological potential of hydrogels as functional materials for thermal management. The hydrogel-made heat sink (HHS) is a PVA hydrogel's slab (50 mm x 50 mm x 5 mm) in which an internal channel (U shape, diam. 2 mm) is obtained by mold casting. When the HHS is exposed to air, it is self-cooled by evaporation of water from its surface. It was possible to decrease the temperature of a water stream by flowing it into the HHS's channel. The cooling performances of the HHS were measured experimentally in function of the water flow rate: the specific cooling power ranged from 340 to 1012 W/m(2). The HHS was analyzed using a heat and mass transfer model, supported by direct measurements of temperature, weight change and heat flux: it was demonstrated that evaporation of water contributed for at least 51-79% of the total cooling power. The heat transfer coefficient K and the mass transfer coefficient h(evap) of the HHS were determined based on the experimental results and the methodology is proposed for comparison with other HHS or cooling technologies. (C) 2019 Elsevier Ltd. All rights reserved.