| The original concept of phase-separation condensation microchannel was proposed to achieving the goal of heat transfer enhancement and pressure reducing.Micro electro mechanical system(MEMS)was used to process the phase-separation microchannel(PSC)and bare microchannel(BC).State contact angle on ion etching silicon surface was measured to quantify the wettability of the processed surface.Single-phase heat calibration was performed before the formal experiment to validate the heat transfer process inside the test section.Comparative experiments was conducted with distilled deionized water as working fluid.The bottom of microchannel test section was attached to a copper block cooled by temperature-controlled flowing cold water with the mass flow rate of 600g/h,1700g/h,2700g/h,respectively.And the inlet vapor pressure range 25kPa~130kPa.Experiment data was acquired by synchronized high performance data acquisition system.The results showed that the condensation flow pattern was significantly different between bare microchannel and phase-separation microchannel.The “Door-Type” micro pin fin structure had liquidimbibitions performance.The tiny droplets could be drawn in the “Door-Type” micro pin fin structure,which can effectively prevent the occurrence of tiny droplets in phaseseparation microchannel.The phase-separation microchannel had the effect of vapor and liquid phase flow separation.In the case of small and medium condensate flow,Both heat transfer enhancement and pressure reduction were achieved by phase-separation microchannel.The effect of heat transfer enhancement is better in the front of microchannel.In the case of big condensate flow,the phase-separation microchannel had no effect of heat transfer enhancement and pressure reduction.Finally,the energy dissipation method was proposed to understand pressure reducing mechanism.And heat transfer enhancement by phase separation microchannel was analyzed by the film control model proposed. |
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