Experimental study on boiling heat transfer in negative-pressure flowing water in a vertical annular tube

To study energy recovery from low temperature wastewater during industrial production, a water-boiling heat transfer experimental device was built. A casing evaporator with length of 1450 mm, an inner tube diameter 30 and annular space gap 14.2 mm is taken as the main research object. The boiling characteristics water in area were experimentally studied by adjusting inlet (60? 85?C) hot pressure (12.1-57.6 kPa). results show that, system decreases, phenomenon becomes more intense convective coeffi-cient increases. flow average surface enhancement rates, ? , 2.2 1.5 when initial 1 kPa used. When rate working medium 1.69 kg?m2/s, coefficient gradually increased then stabilized reached between 80?C 85?C. These reveal boiling-water aid design pipe systems for waste-heat recovery.