{"title":"NUMERICAL STUDY ON HYDROGEN BUBBLE PRODUCTION AND OVERPOTENTIAL IN WATER ELECTROLYSIS","authors":"S. Park, G. Son","doi":"10.6112/kscfe.2023.28.3.064","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.064","url":null,"abstract":"In water electrolysis, bubbles generated between electrodes increase the electric potential required for water splitting. In this work, a numerical analysis of bubbly flow in water electrolysis is conducted using an Eulerian two-fluid method to investigate the interaction of bubble generation and electric potential. The electric potential field is solved by combining with a Tafel equation to consider the overpotential in an electrolysis cell. The present simulation demonstrates that the ohm resistance within the fluid region increases nonlinearly as the electric current density increases, indicating that the hydrogen production efficiency decreases at high current densities. The inlet velocity is observed to be a key factor to decrease the ohm resistance within the fluid region. The effects of inlet velocity and current density on the bubbly flow and electric overpotential are investigated.","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"2014 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"NON-DIMENSIONAL ANALYSIS OF FILM INSTABILITY POINTS OF LIQUID FILM DEVELOPING OVER A ROTATING DISK VIA HIGHLY RESOLVED SIMULATIONS","authors":"J. Won, T. Kim, J. Park, S. Kang","doi":"10.6112/kscfe.2023.28.3.018","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.018","url":null,"abstract":"A liquid jet developing into a liquid film over a rotating disk is found in various industrial applications such as semiconductor manufacturing processes. The liquid film develops various instabilities such as the spiral wave and film break-up. This study performs a non-dimensional analysis on these film instability points. High-fidelity flow simulations are performed for a parametric study based on the rotation rate, flow rate, liquid viscosity, surface tension, and contact angle (CA). A non-dimensional model for the instability points is derived using the Buckingham‘s PI theorem. Parameter sensitivity analyses are performed using the simulation results for a reduced model. The spiral wave starting point is affected mainly by the Reynolds number and capillary number, but not by CA. Also, a reduced non-dimensional model using a single parameter can be derived by combining the non-dimensional parameters. On the break-up point, the surface tension and CA have primary effects, and the capillary number and CA are found to be the main non-dimensional parameters. Based on this finding, a reduced non-dimensional model that predicts the break-up point is derived.","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"RANS ANALYSIS OF FLOWS THROUGH AN OPEN-CENTERED SWIRL GENERATOR COMBINED WITH A 90-DEGREE PIPE ELBOW","authors":"J. Lee","doi":"10.6112/kscfe.2023.28.3.092","DOIUrl":"https://doi.org/10.6112/kscfe.2023.28.3.092","url":null,"abstract":"The effect of the open-centered swirl generator (SG) on the flow in a pipe elbow was investigated. Steady RANS analysis with the shear stress transport (SST) model was performed to obtain flow fields using commercial CFD software. The working fluid and the bulk velocity were set to air and 1 m/s, respectively. When the SG of this study was installed downstream of the elbow, the maximum velocity region after the elbow was quickly guided to the center of the pipe and generated an axial swirl. Instead, the pressure drop increased due to the flow resistance compared to the case without the SG. Depending on the location of the SG, the difference in the flow field was shown as a result of the interaction with the flow passing through the elbow. Among the three locations considered in this study, the flow resistance was minimized when the SG was installed upstream. When the SG was installed downstream, both the vortex and the TKE were predicted to be the maximum.","PeriodicalId":496738,"journal":{"name":"Han'gug jeonsan yuchegong haghoeji","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}