Heat Transfer Enhancement of Mist Flow in Channels with High Heat Flux Components
Traditional cooling with the single phase fluid is not sufficient to satisfy the increasing demand of the cooling requirement in industry. Cooling with the mist flow is a promising technology which can be applied to the advanced hydrogen-fueled gas turbine engines and future electronic systems. By circulating the mist flow in the flow channel, a thin liquid film can be formed on the surface and large amount of heat can be removed by the evaporation on the surface of the liquid film. It can be used to remove high heat flux at a relatively low and uniform temperature and achieve better cooling performance than the conventional forced convective cooling. Mist flow can cover large heat transfer area in longer channels and it is fundamentally different from the conventional spray impingement cooling, which cools the target surface by direct liquid drop impingement. Due to geometry characteristics of the high heat flux component arrangements in the real application, the induced secondary flow, such as flow reattachment or circulation, may influence cooling performance by the mist flow. This proposal studies mist flow characteristics and the corresponding heat transfer behavior. In the first year, a device for simultaneously measurement of the liquid drop size and flow velocity of the mist flow will be established. It utilizes the cheaper LED light as the illumination source to obtain the shadow image of the particles, and the particle size and flow velocity can be calculated based on the image. It has the combined advantages of the velocity measurement by the Particle Image Velocimetry (PIV) and the particle size measurement by the Laser Doppler Anemometry (LDA); in the second year, effect of liquid drop size and mist flow velocity on heat transfer will be investigated based on the mist flow characteristics obtained in the first year. Cooling performance will be tested in the channels with high heat flux components fabricated on the surface arranged in rectangular arrays or cylindrical arrays. The results can be used for evaluating better design with the mist flow cooling technology for future applications in industry.