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외경 5mm 수직 평활관 및 마이크로핀관 내의 이산화탄소/프로판 혼합냉매의 증발열전달 특성에 관한 실험적 연구
조진민,김민수 대한설비공학회 2009 설비공학 논문집 Vol.21 No.4
Refrigerant mixtures provide an opportunity to adjust their properties to fit design criteria and a possibility to create new blends that can improve heat transfer characteristics. Therefore, mixture of CO2 and propane is chosen which may be a promising refrigerant and has good environmental compatibility. This paper presents measured heat transfer coefficient data during evaporation process of CO2/propane mixtures flowing upward in vertical smooth and micro-fin tubes. Smooth and micro-fin tubes with outer diameters of 5mm and length of 1.44m were selected as test tubes. The tests were conducted at mass fluxes of 212 to 656kg/㎡s, inlet temperatures of -10 to 30℃, heat fluxes of 15 to 60kW/㎡ and for several compositions (75/25, 50/50, 25/75wt%). Among CO2/propane refrigerant mixtures, the heat transfer characteristics are much better than that of any compositions when the composition is 75/25 (wt%).
Chronic intermittent form of isovaleric aciduria in a 2-year-old boy
조진민,이범희,김구환,김유미,최진호,유한욱 대한소아청소년과학회 2013 Clinical and Experimental Pediatrics (CEP) Vol.56 No.8
Isovaleric aciduria (IVA) is caused by an autosomal recessive deficiency of isovaleryl-CoA dehydrogenase (IVD). IVA presents either in the neonatal period as an acute episode of fulminant metabolic acidosis,which may lead to coma or death, or later as a “chronic intermittent form” that is associated with developmental delays, with or without recurrent acidotic episodes during periods of stress, such as infections. Here, we report the case of a 2-year old boy with IVA who presented with the chronic intermittent form. He was admitted to Asan Medical Center Children’s Hospital with recurrent vomiting. Metabolic acidosis,hyperammonemia, elevated serum lactate and isovalerylcarnitine levels, and markedly increased urine isovalerylglycine concentration were noted. Sequence analysis of the IVD gene in the patient revealed the novel compound mutations—a missense mutation, c.986T>C (p.Met329Thr) and a frameshift mutation, c.1083del (p.Ile361fs*11). Following stabilization during the acute phase, the patient has remained in a stable condition on a low-leucine diet.
CO₂/propane 혼합냉매의 경사평활관내 상향유동 증발열전달 특성에 관한 실험적 연구
조진민(Jin Min Cho),김용진(Yong Jin Kim),이재승(Jae Seung Lee),김민수(Min Soo Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
There have been many studies on the heat transfer characteristics of natural refrigerant in horizontal tube since new alternative refrigerants such as HC (hydrocarbon) series refrigerants, CO₂, etc. were focused by many researchers. Thus, this paper presents evaporative heat transfer characteristics of CO₂/propane refrigerant mixtures flowing upward in an inclined tube where very limited heat transfer data were produced in the past literature. The effect of mass flux, heat flux and several compositions have been investigated and analyzed. A test tube with outer diameter of 5 ㎜ and length of 1.44 m was selected as a test tube. The test was conducted at mass fluxes of 212 to 656 ㎏/㎡s, heat fluxes of 15 to 60 ㎾/㎡, inlet temperatures of -5 to 30℃, and for several compositions of CO₂/propane(75/25, 50/50, 25/75 wt%). The heat transfer coefficients for inclined tube (45°) are relatively better than those for horizontal or vertical tube. Moreover, among CO₂/propane refrigerant mixtures, the beat transfer coefficients for 75/25 wt% are 120~150% higher than those for 25/75 wt%.
이산화탄소 / 프로판 혼합냉매의 수평평활관 및 마이크로 핀관에서의 증발열전달에 관한 실험적 연구
조진민(Jin Min Cho),김용진(Yong Jin Kim),김민수(Min Soo Kim) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.4
Evaporation heat transfer characteristics of CO₂/propane mixtures in horizontal smooth and micro-fin tubes have been investigated by experiment. The experiments were carried out for several test conditions of mass fluxes, heat fluxes, compositions of CO₂/propane refrigerant mixtures and tube geometries. Direct heating method was used for supplying heat to the refrigerant where the test tube was uniformly heated by electric current which was applied to the tube wall. Heat transfer coefficient data during evaporation process of CO₂/propane mixtures were measured for 5 m long smooth and micro-fin tubes with outer diameters of 5 ㎜, respectively. The tests were conducted at mass fluxes of 318 to 997 ㎏/㎡s, heat fluxes of 6 to 20 kW/㎡ and for several mixture compositions (100/0, 75/25, 50/50, 25/75, 100/0 by wt% of CO₂/propane). The differences of heat transfer characteristics between smooth and micro-fin tubes for various compositions of CO₂/propane refrigerant mixtures and the effect of mass flux, and heat flux on enhancement factor (EF) and penalty factor (PF) were presented.
수직 마이크로핀관내 C₂/propane 혼합냉매의 상향유동 증발열전달 특성에 관한 실험적 연구
조진민(Jin Min Cho),김용진(Yong Jin Kim),김민수(Min Soo Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Several kinds of alternative refrigerants have been developed and attracted a significant attention because of environmental problems caused by conventional refrigerants. This paper presents evaporative heat transfer characteristics of CO₂/propane refrigerant mixtures flowing upward in a vertical micro-fin tube. The effect of mass flux, heat flux and several compositions have been investigated and analyzed. Before the test section, a pre-heater is installed to adjust the inlet quality of the refrigerant to a desired value. A micro-fin tube with outer diameter of 5 mm and length of 1.44 m was selected as a test tube. The test was conducted at mass fluxes of 212 to 530 ㎏/㎡s, heat fluxes of 15 to 45 ㎾/㎡, inlet temperatures of -5 to 30 , and for several compositions (75/25, 50/50, 25/75 wt%). Among CO₂/propane refrigerant mixtures, the heat transfer characteristics are much better than that of any compositions when the composition is 75/25(wt%)