S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Mechanical Aerospace Engineering (기계항공공학부) Theses (Ph.D. / Sc.D._기계항공공학부)
Analysis of Relative Humidity Effects on Ejector Performance
- 공과대학 기계항공공학부
- Issue Date
- 서울대학교 대학원
- 학위논문 (박사)-- 서울대학교 대학원 공과대학 기계항공공학부, 2017. 8. 송성진.
- Pumping in ejectors is a measure of how much the secondary fluid is entrained by the high momentum primary flow and is one of the crucial performance indices. In the fuel recirculation system of fuel cells, the entrained secondary fluid contains water vapor due to the over-supplied hydrogen, making the secondary fluid humid. In such cases, the relative humidity of the secondary fluid alters the fluid properties of the mixed flow. This study examines such effects of relative humidity on ejector. A new analytical model has been developed, and series of measurements has been conducted to validate the models prediction. The present results demonstrate that higher relative humidity of the secondary fluid reduces pumping in an ejector. During the mixing process of the two fluids, condensation releases heat, increasing the ejector operating temperature. Thus, secondary flow density is decreased, and pumping is lowered.