Abstract: Two different electrode arrangements were designed to introduce the electric field into microchannels to investigate the flow boiling heat transfer characteristics of microchannels under the effect of electric field． Refrige- rant R141b was taken as the working fluid to research the influence of electric field on the flow boiling heat transfer in microchannels with designed capacity of system pressure at 140 kPa and inlet temperature at 305.65 K． The experi- mental results indicate that the electric field can enhance heat transfer of microchannels and the boiling curve of needle electrode is obviously shifted to the left． Unlike needle electrode，the boiling curve of wire electrode over- laps with the 0V and 250V and the other boiling curves are obviously shifted to the left，which manifests that the ef- fective voltage of wire electrode for strengthening is higher than that of the needle electrode． The saturated boiling heat transfer coefficient of two electrode arrangements increases first and then decreases with the increase of heat flux，and increases with the increase of mass flow rate． Compared to the electrical field-free，the saturated boiling heat transfer coefficient was increased by 39%，62%，77% respectively under three kinds of needle electrode of 250，550，850 V，and by 0%，50%，82% respectively under three kinds of wire electrode． At low voltage，the enhanced heat transfer factor of needle electrode is greater than that of the wire electrode，and the opposite is true for high voltage． Under the experimental condition，the maximum heat transfer enhancement factor of needle electrode is 1. 77，and that of the wire electrode is 1. 82．

Key words: microchannels, electrical field, heat transfer enhancement, flow boiling, needle electrode, wire electrode