EXPERIMENTAL INVESTIGATION OF TWO-PHASE MIST FLOW AND HEAT TRANSFER IN POROUS MEDIA

An experimental investigation was conducted to examine steady, air-water mist flow in a porous material. The aim was to quantify the effects of various operating and design parameters on the cooling effectiveness. Parameters tested included the porous material type, porous material porosity and permeability, diameter and thermal conductivity, carrier gas velocity, and channel characteristics on the heat transfer rate and pressure drop. The results are compared with the single-phase flow where no mist was used. A fully instrumented experimental test facility that included a cylindrical and a rectangular electrically heated test section was used. Water was used as the mist liquid, with air as the carrier gas. Local heat transfer coefficients, defined based on the temperature difference between the heated surface and the bulk gas, were obtained along the channels for a wide range of operating conditions. The data indicate that mist cooling can increase the heat transfer coefficient by more than an order of magnitude compared to forced convection using only the carrier gas in porous media.