Study on Heat Transfer Characteristics for Single-phase Flow in Rectangular Microchannels

In this study, experiments were carried out to investigate the convective heat transfer characteristics of rectangular microchannels. The sample used in the experiments contained 20 rectangular microchannels in parallel. The channels had a hydraulic diameter of 700 μm. Distilled water was used as the working fluid. In the experiments, the Reynolds number ranged from 400 to 800, heat flux ranged from 35 to 85 kW/m2, and the inlet fluid temperature was 20 .deg. C. As a result, the convective heat transfer coefficient increased upon increasing the Reynolds number and ranged from 4.6 to 6.4 kW/m2/ .deg. C in the thermally fully developed region. Moreover, the higher the Reynolds number, the longer the thermal entry length in the rectangular microchannels. However, it was observed that a variable heat flux did not affect the thermal entry length. In conclusion, a correlation was proposed to indicate the heat transfer characteristics in a thermally fully developed region