Heat transfer without phase change of gas-water two-phase flow in microgap

Since the higher function and miniaturized electronic devices need to consume more energy, the heat flux of local area in device will be more than 1000 w/cm2 to cause the concern of heat transfer. This paper studied the heat transfer of air-water two-phase flow in microgap with non-boiling conditions. When the flow rate of DI water was fixed (32~196 ml/min), Nusselt number increased higher with the increasing of Nitrogen flow rate. On the other hand, to fix the flow rate of Nitrogen (64~4096 ml/min), Nusselt number had decreased with the increasing of DI water flow rate. The liquid film thickness played the key role on the heat transfer of the two-phase flow in microgap. The thinner the liquid film was, the better the heat transfer was. Nitrogen had a threshold of flow rate to be 7.5 m/s. To below this value Nusselt number increased with the increasing of DI water flow rate. To above this value, Nusselt number decreased with the increasing of DI water flow rate. This had been contributed to the change of flow pattern on gas-water. The empirical formula was deduced and had a low mean relative error to match the experiment data.