Abstract: Calculate ejecting coefficieat of jet flow using heat balance analysis method , the heat balance is between the heat release of working steam expansion and the heat absorbing of mixing gas to be pressed, this process is heat insulation processing in every stage ejector and the state at exhausting port of ejector must be located truthful superheating situation. Experimental ejecting property of steam-jet pump which is designed has high degree of adaptability comparating with the rata of desiging . Mass flow to be ejected gas by unit mass flow of working steam at same degree of vacuum is increased and the energy consumption is decreased.

Key words: Ejecting coefficient of jet flow, Steam-jet pump