The effect of area ratio on microjet array heat transfer

The heat transfer performance of five submerged and confined microjet arrays using air and deionized water as the working fluids was investigated. Both inline and staggered array arrangements of jet with diameters of 54 and 112 μm were investigated, and the area ratio (total area of the jets divided by the surface area) was varied between 0.036 and 0.35. Reynolds numbers defined by the jet diameter were in the range of 180-5100 for air and 50-3500 for water. A heat flux of 1100 W/cm2 was obtained at a fluid inlet-to-surface temperature difference of less than 30 °C. The results were compared with established correlations, and no evidence was found to suggest that the behavior of submerged and confined jets at the microscale is fundamentally different than at the macroscale. Reynolds number, Prandtl number, and area ratio were found to significantly affect the heat transfer performance, and a curve fit was developed, which correlated 290 of the 295 data points within ±25% with an MAE of 11%.