Experimental Study On Nucleate Boiling Of Seawater At Negative Pressure

The seawater pool boiling heat transfer characteristics at negative pressureoutside the vertical single tube from35g/kg to100g/kg was studied in this paper. Andthe effect of seawater salinity and pressure on boiling heat transfer characteristics wasstudied.The effect of the vacuum degree and the salinity to the wall superheat and onsetof nucleate boiling was theoretically analyzed.An experiment table about pure water and seawater boiling heat transfer undernegative pressure was built. The effect of vacuum degree to the boiling heat transferperformance especially the heat flux, boiling heat transfer coefficient and the wallsuperheat was studied. The seawater salinity not only affected the properties ofseawater, and changed the boiling heat transfer performance. Boiling heat transferperformance changed with seawater salinity was studied though experimental study.Marangoni convection caused by concentration gradient and the disturbance causedby bubble departure occurred in boiling heat transfer were analyzed preliminarily.The results show that the boiling wall superheat and liquid height of the onset ofnucleate boiling increased with increasing pressure, and liquid height of the onset ofnucleate boiling increased with increasing seawater salinity. The seawater boiling heattransfer intensity increased with increasing the degree of vacuum. The seawaterboiling heat transfer intensity increased with increasing seawater salinity first, andthen decreased because of influence of Marangoni convection at natural convectionstate. Bubble disturbance played a dominant role at nucleate boiling heat transfer, andthe seawater boiling heat transfer intensity decreased with increasing seawater salinityslightly.