Evaluation of permeability of ceramic wick structures for two phase heat transfer devices

This work reports on different approaches to predict the pressure drop in capillary structures for two phase heat transfer devices (TPHTD). For this purpose, several porous wick structures were produced by slip casting and characterized concerning their porosity, critical pore diameter, capillary pressure and permeability. The wick structures exhibited porosity in the range of 48–58%, pore diameter ranging from 1 μm to 4 μm, with capillary pressure of 80 and 22 kPa, respectively. Two expressions were developed to simulate the pressure drop permeabilities as a function of the heat load applied to the TPHTD evaporator. The prime target of this work is to evaluate the differences in predicting pressure drop just by using the Darcyan constant, k1, and both by using Darcyan and non-Darcyan constant, k1 and k2. When k1 was used only it was considered as Darcyan approach and when both constants were taken into account it was considered as Forchheimer approach. Additionally, ceramic wick structures have been tested as capillary evaporator in a TPHTD. The startup was successful after 20 min the inlet and outlet evaporator temperatures remain constant. It confirms that all applied heat load was transported to the condenser.