A brass block was constructed as a test block to study the Marangoni condensation in this paper. The maximal temperature difference of the block surface on which pure steam condensed was 11℃ when the block was cooled by the normal temperature water. Regulations and modes of Marangoni condensation for mixture vapor with different mass fractions were studied when the speed of vapor was 0.3m/s. As both temperature gradients and concentration gradients exist on the condensing surface, the experimental results indicate that the maximal heat transfer coefficient of mixture vapor can be 2.8 times that of pure steam when the Marangoni condensation of mixture vapor appears. The heat transfer coefficient of mixture vapor increases with the decrease of surface subcooling, and it appears a steep increase when the surface subcooling is small enough; the heat transfer flux has a maximum value as the surface subcooling rises; and the different modes of condensation are confirmed when the different ethanol concentration and different surface subcooling exist.

The objective of this work is to analyze the performance of steam-driven jet injector for its design and application in the district-heating system. The paper experimentally studied the performance of a steam-driven jet injector with central steam nozzle configuration. Three injectors with throat diameters of 16 and 20mm were tested. The main inlet parameters tested-steam pressure, water pressure and water temperature-were in the range of 0.20-0.60MPa, 0.14-0.49MPa and 18-68C, respectively. Experimental results show that the pressures were almost constant for the steam-water two-phase flow in the variable section channel of the mixing chamber tested, whose values were mainly affected by inlet steam pressure, inlet water pressure and temperature, and a shockwave appeared at the outlet of the mixing chamber. The lifting-pressure coefficient and jet coefficient measured were 1.27-2.1 and 7.63-43.65, respectively. A simplified mathematical model has been developed to predict the performance of the injector based on conservation of mass, momentum and energy as well as the present experimental data. The predictions agreed with the experimental data within