An investigation of the gas-liquid ejector has been carried out to study the influence of operating conditions and ejector geometries on the hydrodynamics and mass transfer characteristics of the ejector by using three-dimensional CFD modeling. The CFD results were validated with experimental data. Flow field analysis and prediction of ejector performance were also conducted. Variations of the operating conditions were made by changing the gas-liquid flow rates ratio in the range of 0.2 to 1.2. The length to diameter ratio of mixing tube (L M /D M ) was also varied from 4 to 10. CFD studies show that at L M /D M =5.5, the volumetric mass transfer coefficient increases with respect to gas flow rate. Meanwhile, at L M /D M =4, the plot of volumetric mass transfer coefficient to gas-liquid flow rate ratio reaches the maximum at gas-liquid flow rate ratio of 0.6. This study also shows that volumetric mass transfer coefficient decreases with the increase of mixing tube length.

Hydrogen fuel cell is a developing technology that allows great amount of electrical power to be obtained using a source of hydrogen gas. It is a proven environment-friendly potential future fuel. During compression of hydrogen gas in reciprocating compressor, pressure fluctuation is built up. The pressure fluctuation and its reduction by the snubber are studied in this experiment. For different motor frequencies, the input and output pressure amplitude varies from 0.228 kPa-2.081 kPa and 0.095 kPa-0.898 kPa. The pressure magnitudes are 101.451-105.172 kPa and 101.388-102.565 kPa for input and output of the snubber, respectively. The acryl snubber reduces 0.796 kPa (57.31%) pressure amplitude on average with restoring its high pressure. Detail information about the pressure including the critical pressure zone inside the tube like snubber part and the whole system can be obtained by CFD.

：Hydrogen energy is becoming popular day by day due to its renewability and pollutaaant free natures. Hydrogen gas pressure which is after passing through reciprocating compressor part has high pulsation wave form. A unit, snubber is used as compressor components to reduce the harmful pulsation waveform and to remove the impurities in the hydrogen gas. An experiment has been conducted to investigate the pulsation reduction performance of different arrangement of snubber i.e. snubber array used in reciprocating compression system. Analyzing the snubber array experimental data, it is found that the pressure fluctuations are reduced from 90.1977% ~ 92.6336% with pressure loss 1.5013% ~ 4.9034% for compressor operation at different speed which ensure the good performance of snubber-array as pulsation damper in hydrogen compressing system.

Hydrogen compressing system is the most important part of hydrogen economy. There develop inherently pressure pulsation in reciprocating hydrogen compressing system. Snubber unit has been employed then to decrease it. An experiment has been conducted to investigate the performance of snubber used in reciprocating compression system. CFD analysis is applied to get the pressure values at different sections of this system. Regression models are also developed for amplitude at input and output of the snubber. A comparative study of pressure and amplitude by experiment, regrssion model and CFD model are performed for 35, 40 and 45hz motor frequency. These models results are varied by 0.844%, 0.117% and 0.475% from the experiment for those motor frequencies.The pressure losses in the snubber are also found almost similar values by the model i.e. 0.024%, 0.030% and 0.016% deviations.