Experimental and theoretical study on performance of bi-porous wick for passive phase-change devices

The driving force of the fluid in passive phase-change devices is provided by the porous wick, and thus, the porous wick is one of the key factors determining the performance of these devices. In this work, the properties of sintered nickel powder porous wicks were systematically studied to give a comprehensive evaluation. Three particle sizes (average diameter 2-20 μm), pore-forming agent concentration (0%-30%wt), and two preparation methods [loose sintering (LS) and cold press sintering] were utilized to prepare 42 samples. The results showed that with the increase in particle size and pore-forming agent concentration and the decrease in preparation pressure, the capillary performance was enhanced due to the improvement in the connectivity of internal pores. However, the strength of the wick decreased. Additionally, an improved model for the capillary wick performance and permeability was proposed by combining the traditional Kozeny-Carman permeability formula with an enhanced permeability equation based on the research outcomes of Byon and Kin. The improved model was specifically optimized for scenarios involving the pore-forming agent. The predicted results agreed well with the experimental data, thoroughly validating the effectiveness of the developed model.