Visualized Experimental Investigation Of Subcooled Flow Boiling Heat Transfer In Horizontal Narrow Annular Channels

There are many application of heat transfer in annular narrow channels in engineering. Two-phase flow boiling heat transfer in narrow channels is an economical and effective forced heat transfer method for its compact structure. Therefore, study on flow boiling heat transfer in narrow channels is significant in order to reduce the size of heat exchanger.Experiments are conducted here to investigate how the channel size and other factors of distilled water affect the subcooled flow boiling heat transfer in a horizontal narrow annular duct. The gap of the duct is at 2.0 and 3.0mm in this study. From the measured boiling curves, the temperature undershoot at ONB is found to be relatively significant for the subcooled flow boiling of distilled water in conduct.The distilled water subcooled flow boiling heat transfer coefficient increases with a reduction in the gap size, but decreases with an increase in the inlet liquid subcooling. Besides, raising rhe imposed heat flux can cause a substantial increase in the subcooled boiling heat transfer coefficient. However, the effects of the water mass flux and saturated temperature on the boiling heat transfer coefficient are small in the narrow duct.A removable and multifunctional experimental device is designed and installed all by the author. Heating way is big electric current and low voltage. Using distilled water as working fluid, the experimental research was performed with visualization method to investigate the onset of nuclear boiling in low pressure in horizontal annular narrow channels.The range of experimental parameter are as follows: system pressureP =0.1⁰.2MPa; mass fluxG =55.4⁵15.6kg/(m²Â·s); heat flux q =49.843-123.083 kW/ m²; inlet subcooled temperature:Δt_sub=30⁶0℃; channel sizes =2³mm.Correlation for the present subcooled flow boiling heat heat transfer data of distilled water in the narrow annular duct is proposed.