60334 - A Study of Flow Characteristics for Improving Fuel Efficiency With Various Configurations of an Ejector in a Fuel Cell 

Renewable energy such as hydrogen or solar energy is promising due to issues around environmental pollution. Hydrogen makes only water and generates electric energy in a fuel cell by reacting electrochemically with air. The fuel cell consists of many parts such as a cell stack, an ejector, a tank, and a regulator, etc. In the ejector, hydrogen, a primary fluid, stored in a high-pressure tank passes through a nozzle. Recirculated hydrogen, a secondary fluid, is mixed with the primary fluid in a suction chamber. Both of which are supplied to the cell stack through a diffuser and generates the electric energy in the cell stack. Since the ejector is related to energy efficiency, many researchers have conducted research to improve the performance of the ejector. In this study, an inflow ratio (a ratio of a mass flow rate of the secondary fluid to a mass flow rate of the primary fluid) and backpressure in the diffuser were evaluated with varying an inlet diameter of the suction chamber and the diffuser length. The inflow ratio and backpressure were assessed using computational fluid dynamics. Also, flow characteristics in the ejector were investigated to determine where a vortex occurs in the diffuser. The results of the analysis were shown graphically according to various geometric condition changes.