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RISS 인기검색어
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- 저자 : 조유연 ( Yoo Yeon Jo ) (검색결과 2 건)
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조유연 ( Yoo Yeon Jo ),정수권 ( Su Kwon Jung ),이오람 ( Oh Ram Lee ),김의용 ( Eui Young Kim ) 서울시립대학교 산업기술연구소 2006 산업기술연구소논문집 Vol.14 No.-
Heat transfer process is important for many applicable fields such as heat exchanger, construction material, and aircraft body. Heat conduction is much affected by contact resistance between two different material interfaces. In this study, various experimental conditions were tested to decrease contact resistance and to increase thermal conductivity with several coating materials. Aluminium pieces of 2 mm, 4 mm were used as test samples. Copper powder (a few micrometer diameter), copper powder/silicon oil (80/20 weight ratio), and conductive paste were used as coating materials. When the conductive paste and (copper powder+silicon oil) blend were used, thermal conductivity was higher than when no coating materials were used. However, when only the copper powder was used, thermal conductivity value was not stable enough.
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Development of a Durable Startup Procedure for PEMFCs
김재홍(Kim, Jae-Hong),조유연(Jo, Yoo-Yeon),장종현(Jang, Jong-Hyun),김형준(Kim, Hyung-Juhn),임태훈(Lim, Tae-Hoon),오인환(Oh, In-Hwan),조은애(Cho, Eun-Ae) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
Various polymer electrolyte membrane fuel cell (PEMFC) startup procedures were tested to explore possible techniques for reducing performance decay and improving durability during repeated startup-shutdown cycles. The effects of applying a dummy load, which prevents cell reversal by consuming the air at the cathode, on the degradation of a membrane electrode assembly (MEA) were investigated via single cell experiments. The electrochemical results showed that application of a dummy load during the startup procedure significantly reduced the performance decay, the decrease in the electrochemically active surface area (EAS), and the increase in the charge transfer resistance (R_{ct}), which resulted in a dramatic improvement in durability. After 1200 startup-shutdown cycles, post-mortem analyses were carried out to investigate the degradation mechanisms via various physicochemical methods including FESEM, an on-line CO₂ analysis, EPMA, XRD, FETEM, SAED, FTIR. After 1200 startup-shutdown cycles, severe Pt particle sintering/agglomeration/dissolution and carbon corrosion were observed at the cathode catalyst layer when starting up a PEMFC without a dummy load, which significantly contributed to a loss of Pt surface area, and thus to cell performance degradation. However, applying a dummy load during the startup procedure remarkably mitigated such severe degradations, and should be used to increase the durability of MEAs in PEMFCs. Our results suggest that starting up PEMFCs while applying a dummy load is an effective method for mitigating performance degradation caused by reverse current under a repetition of unprotected startup cycles.
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