Critical heat flux enhancement on a downward face using porous honeycomb plate in saturated flow boiling

Enhancing the Critical Heat Flux (CHF) is extremely needed in some engineering applications. Many methods involving nanofluids and surface modifications have been investigated to enhance the CHF. Most of the previous works focus on pool boiling and upward-facing surface conditions. An experimental research on enhancing the CHF in downward-facing saturated flow-boiling conditions was performed by attaching a metal porous honeycomb plate. The experiments were conducted under four different flow rates: 160, 320, 640, and 1280 kg/(m2 s). It was found that the porous honeycomb plate can both enhance the CHF and reduce surface superheat at all four flow rates. However, the CHF increase ratio decreased as the flow rate increased, i.e., from 2.4 at 160 kg/(m2 s) to 1.1 at 1280 kg/(m2 s). The enhancement effect is attributed to the honeycomb structure and water supply through the porous media of the honeycomb. The role of the water supply through the metal porous media was investigated.