Heat Transfer Characteristics of Spray Cooling on Micro-structured Surface

Experiments are conducted to study the heat transfer characteristics of micro-structure and flat surface in spray cooling. The micro-structured surfaces including square pin fins, straight rectangular fins and fan fins along with a referenced flat surface are tested in a closed loop system with water as the working fluid. The experimental results indicate that the fin arrangement rather than a simple increased wetted area plays significant role on the spray cooling performance of the micro-structure surface. Using a flat surface as reference, the micro-structured surface produced more or less enhancement in spray cooling than the flat surface. The micro-structure is indicated can improve the heat flux, acquired higher CHF. In addition, to improve heat transfer, the micro-structure surface provides other advantages such as reducing the time of transition to two phase regime. And the micro-structure surface with square pin fins outperformed the surface with straight rectangular fins and fan fins. However, there exists a relative more serious temperature non-uniformity phenomenon on the enhanced surface than flat surface, and it can be improved by reducing the system pressure.