Effects of pin and wire electrodes on flow boiling heat transfer enhancement in a vertical minichannel heat sink

Abstract

In this paper, electrohydrodynamic (EHD) enhancement of flow boiling heat transfer in a vertical minichannel heat sink was investigated experimentally. The pin and wire electrodes are used to create different kinds of non-uniform electric fields. Flow boiling experiments of refrigerant R-141b under electric fields are conducted under various applied voltages. The results show that the application of pin and wire electrodes can promote the Onset of Nucleate Boiling (ONB) and effectively enhance heat transfer coefficient. For the pin and wire electrodes, the EHD enhancement effect increases with the increase of applied voltage. At the same heat flux, heat transfer enhancement for pin electrode is higher than that for wire electrode at low applied voltage (U ≤ 400 V), but is lower than that for wire electrode at high applied voltage (U ≥ 550 V). Moreover, the obtained maximum enhancement ratio for pin and wire electrodes could reach 1.72 and 1.80, respectively. The influence area of pin electrode is limited, whereas the influence area of wire electrode is the entire electrode length at U ≥ 400 V. Based on the simulation and experiment results, the enhancing mechanism of EHD on flow boiling heat transfer in minichannel was discussed.