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An Experimental Study of a Variable Ejector for the Hydrogen Fuel Cell System
J.-H. Lee, H.-D. Kim, T. Setoguchi and S. Matsuo

The present study describes a new method to improve the performance of the ejector which can be employed for the automobile hydrogen fuel cell system. A cone cylinder is inserted into a conventional ejector-diffuser system and enables the ratio of the nozzle throat area to the ejector throat area to be varied with the output power of the hydrogen fuel cell system. Experiment is carried out to investigate the operation characteristics of the variable sonic and supersonic ejector systems. For a wide range of the operation pressure ratios of the ejector system, the mass flow rate of suction flow is measured. The results obtained show that the present variable ejector system can control the suction flow rate at a fixed operation pressure ratio, and that the sonic ejector is considerably different from the supersonic ejector system. As the ejector throat area ratio increases, the re-circulation ratio of suction flow increases for the sonic ejector, but it decreases for the supersonic ejector. It is known that the present variable ejector system can effectively control the suction mass flow rate, and is practically useful for application to the automobile hydrogen fuel cell system.

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