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실제기체의 물성을 이용한 Stirling 냉동기 단열해석
백종훈,장호명,Baik, J.H.,Chang, H.M. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.1
A Finkelstein adiabatic analysis is performed for Stirling refrigerator with real gas properties of helium. The mass balance and the energy balance equations are formulated into the form that is convenient for incorporating an available computer code of the helium properties. The differential equations are solved numerically. The calculated coefficient of performance(COP) and the pressure variation are compared with the results obtained when helium is assumed to be an ideal gas. The relative errors in COP are presented as functions of the refrigeration temperature and the maximum cycle pressure.
백종훈,장호명,Baik, J.H.,Chang, H.M. 대한설비공학회 1996 설비공학 논문집 Vol.8 No.2
A cycle analysis is performed to investigate how the non-ideal gas behavior of helium reduces the heating capacity of VM heat pumps. Since the operating pressures of VM heat pumps are as high as 1 to 20 MPa, the compressibility factor of helium becomes clearly greater than 1 and the non-ideal behavior always represents a thermal loss in heating. To calculate the amount of the losses, an adiabatic cycle analysis is performed with the real properties of helium and the net enthaply flows through the two regenerators are numerically obtained. It is shown that the non-ideal gas losses could be as much as 8% in the heating capacity when the operating pressures are greater than 10MPa. The effects of the operating temperatures and the dead volumes on the loss are presented.
백종훈,강병하,장호명,Baik, J.H.,Kang, B.H.,Chang, H.M. 대한설비공학회 1997 설비공학 논문집 Vol.9 No.3
A hydrogen liquefaction equipment by direct cooling has been designed and built at KIST. Cool-down characteristics and liquefaction performance of the equipment have been investigated. The hydrogen liquefaction equipment consists of a GM refrigerator, a liquefaction velssel, a radiation shield and a cryostat. It is found that the hydrogen starts to be liquefied in the liquefaction vessel after 40~50 minutes of cool-down from the gas state of 270K. The effect of natural convection phenomena of charged gas in liquefaction vessel on the cool-down characteristics is evaluated by comparing with those in vacuum of liquefaction vessel. It is seen that the cool-down time of a liquefaction vessel is substantially increased in vacuum environment of liquefaction vessel. The experiments have been performed for 1~5 atm of hydrogen pressure to investigate the influence of hydrogen pressure on the liquefaction rate and figure of merit(FOM). It is found that both liquefaction rate and FOM are increased as the charged hydrogen pressure is increased.
백종훈(J . H . Baik),강병하(B . H . Kang) 한국수소및신에너지학회 1998 한국수소 및 신에너지학회논문집 Vol.9 No.3
The ortho-para H<sub>2</sub> catalytic conversion equipment has been developed to reduce the evaporation loss from stored liquid hydrogen. The ortho-para H<sub>2</sub> conversion heat is evaluated at liquid nitrogen temperature. This problem is of particular interest in the design of the ortho-para H<sub>2</sub> conversion equipment consists of a catalytic converter, a precooler, and a liquid nitrogen bath. 30-90 cc of Fe(OH)<sub>3</sub> are employed as a catalyst in the present converter. The conversion heat and conversion effectiveness are evaluated when mass flow rate of hydrogen is in the range of 0.05-1.6 g/min. It is found that the ortho-para H<sub>2</sub> conversion heat is increased while conversion effectiveness is decreased as the mass flow rate of hydrogen is increased. Both the ortho-para conversion heat and conversion effectiveness are increased with an increase in the amount of the catalyst.
최항집(H . J . Choi),백종훈(J . H . Baik),강병하(B . H . Kang),최영돈(Y . D . Choi) 한국수소및신에너지학회 1999 한국수소 및 신에너지학회논문집 Vol.10 No.1
The effectiveness of a double-tube heat exchanger has been investigated experimentally. This problem is of particular interest in the design of the heat exchanger in a hydrogen liquefaction system. Temperature, pressure, and mass flow rate for hydrogen were measured both in inner tube and in annulus of a double-tube heat exchanger. The effectiveness could be evaluated from the measured temperature and mass flow rate. It is found that the effectiveness increases with an increase in the heat transfer area of a double-tube heat exchanger and with a decrease of the heat capacity ratio. But the increase rate of the effectiveness decreased with a decrease of the heat capacity ratio. Therefore, it is presented that a criterion for selecting the heat exchanger length and heat capacity ratio to obtain the effectiveness required in a hydrogen liquefaction system.