한국유체기계학회 논문집Pub Date : 2023-10-31DOI: 10.5293/kfma.2023.26.5.111
Hyeonseok Seo, Inju Hwang
{"title":"Numerical Study on the Diffusion Characteristics and Ventilation under Hydrogen Leakage in the Underground Hydrogen Facilities","authors":"Hyeonseok Seo, Inju Hwang","doi":"10.5293/kfma.2023.26.5.111","DOIUrl":"https://doi.org/10.5293/kfma.2023.26.5.111","url":null,"abstract":"Hydrogen storage and supply system such as a hydrogen charging station needs to sufficient safety distance which are constructed on the ground space, but considering the use of domestic land space in Korea, it is already difficult to secure ground space due to high density development including the urban planning. Various studies are being conducted on the undergroundization of the hydrogen system to solve this problem, but the risk of explosion and fire should be considered when the gaseous hydrogen leaks including the concentration of hydrogen reaches more than 4% (Limit Flammability Level, LFL). Preventing these problems, the concentration of leakage hydrogen should be diluted using the proper ventilation methods in underground space. According to the NFPA, ventilation performance need to allow dilution below 25% of the LFL (1% hydrogen concentration). In this study, we investigated the diffusion phenomena of leakage hydrogen and ventilation performance when gaseous hydrogen leaks from underground facilities numerically, and suggested to reduce the hydrogen volume fraction in it. The flow rate at exhaust port, the number of exhaust port and inlet port were considered the design parameters in this study. The flow characteristics of leaking gaseous hydrogen was set based on the volume average concentration, the ventilation performance according to the variables was quantitatively checked, and the ventilation performance was analyzed through the stagnation region and residual hydrogen volume fraction in underground space.","PeriodicalId":491641,"journal":{"name":"한국유체기계학회 논문집","volume":"2 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135928662","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}
한국유체기계학회 논문집Pub Date : 2023-10-31DOI: 10.5293/kfma.2023.26.5.089
Sejin Yoon, Jaehun Heo, Donghoon Kwak, Jongin Bae
{"title":"Pressure Drop and Heat Transfer Performance Effects due to Deformation of Channels in Cold Plate After Diffusion Bonding","authors":"Sejin Yoon, Jaehun Heo, Donghoon Kwak, Jongin Bae","doi":"10.5293/kfma.2023.26.5.089","DOIUrl":"https://doi.org/10.5293/kfma.2023.26.5.089","url":null,"abstract":"In channels with small hydraulic diameters, even slight geometric deformations can significantly affect thermal performance. This study investigates the impact of deformation due to diffusion bonding on heat transfer characteristics in the internal channel shape of a liquid cooling cold plate with various pin-fin structures. Deformation amounts were measured and predicted using a generalized formula, and three-dimensional numerical simulations were conducted to analyze heat transfer performance. Results showed that heat transfer performance varied depending on the pin-fin structure, with straight fins decreasing and multi pins improving after deformation. The study suggests that thermal flow analysis can predict changes in heat transfer coefficient, facilitating the design of more efficient cold plates with optimized channel section shapes.","PeriodicalId":491641,"journal":{"name":"한국유체기계학회 논문집","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135928661","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}
한국유체기계학회 논문집Pub Date : 2023-10-31DOI: 10.5293/kfma.2023.26.5.105
Kisung Lim, Chanyoung Kim, Rojun Park, Sangho Moon, Hyunchul Ju
{"title":"Enhancing PEMFC Performance through Orifice-shaped Cathode Flow Field Designs","authors":"Kisung Lim, Chanyoung Kim, Rojun Park, Sangho Moon, Hyunchul Ju","doi":"10.5293/kfma.2023.26.5.105","DOIUrl":"https://doi.org/10.5293/kfma.2023.26.5.105","url":null,"abstract":"This study applied a multiscale, multiphase PEMFC model to simulate the cell performance for three different cathode flow field designs, including conventional(rectangular, trapezoidal), and orifice-shaped flow field designs. The results demonstrated that the orifice-shaped flow field designs allowed for uniform distribution of oxygen concentration, ensuring its efficient supply to the outlet. Also, at a high current density of 2.0A/cm², the orifice-shaped design exhibited reduced concentration losses and improved performance compared to conventional flow field designs.","PeriodicalId":491641,"journal":{"name":"한국유체기계학회 논문집","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135928500","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}
한국유체기계학회 논문집Pub Date : 2023-10-31DOI: 10.5293/kfma.2023.26.5.053
Jeong-Woo Kwon, Joon Ahn
{"title":"A Study on the One-dimensional Design Equation of a Stepped Labyrinth Seal","authors":"Jeong-Woo Kwon, Joon Ahn","doi":"10.5293/kfma.2023.26.5.053","DOIUrl":"https://doi.org/10.5293/kfma.2023.26.5.053","url":null,"abstract":"The performance of Labyrinth seal for sealing the secondary flow path of a gas turbine was predicted using Flomaster, a 1-dimensional code. First, the predictive ability of the straight-through seal module built into Flomaster was verified by comparing it with experimental data. The discharge coefficient was confirmed through the isentropic mass flow rate and the actual mass flow r ate found in Martin’s equation. The validity of the prediction using the one-dimensional code was verified through the straight-through seal, and the discharge coefficient according to the geometric variables was predicted using the stepped seal module built into the Flomaster. The performance of the seal predicted by the one-dimensional code was verified by comparing the results obtained with the three-dimensional CFD (computational fluid dynamics) data. Among the design variables of the stepped seal, the most important variable is the step height, but the effect is reduced above a certain height, so the design equation of the one-dimensional code could be used.","PeriodicalId":491641,"journal":{"name":"한국유체기계학회 논문집","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135928659","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}