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- 저자 : 최항집(H . J . Choi) (검색결과 2 건)
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김서영(S . Y . Kim),강병하(B . H . Kang),최항집(H . J . Choi) 한국수소및신에너지학회 1998 한국수소 및 신에너지학회논문집 Vol.9 No.4
An experimental study on effect of vapor-cooled heat stations in a 5.5 liter cryogenic vessel has been performed. The cryogenic vessel is made of stainless steel of thickness of 1㎜ and insulated by the combined insulation of vacuum, MLI (multi-layer insulation) and vapor-cooled radiation shield. Vapor-cooled heat stations are also constructed based on the 1-dimensional thermal analysis to reduce the heat inleak through a filling tube. Thermal analysis indicates that the vapor-cooled heat stations can substantially enhance the performance of vessel for cryogenic fluids with high C<sub>p</sub>/h<sub>fg</sub>, where C<sub>p</sub> the specific heat and h<sub>fg</sub> the heat of vaporiaation, such as LH₂ and LH₂. The experimental results for LN₂ shows that the total heat inleak into inner vessel consists of 14% radiation and 86 % conduction through the filling tube. Therefore, it is expected that the conduction heat inleak of the vessel for high C<sub>p</sub>/h<sub>fg</sub> cryogenic fluids can be significantly reduced. powders. The amount of copper coating was 20wt%. In order to examine corrosion behavior of the electrodes, the corrosion current and the current density, in 6M KOH aqueous solution after removal of oxygen in the solution, were measured by potentiodynamic and cyclic voltamo methods. The results showed that Co in the alloy increased corrosion resistance of the electrode whereas Ni decreased the stability of the electrode during the charge-discharge cycles. The exectrode used Si sealant as a binder showed a lower corrosion current density than the electrode used PTFE and the electrode used Cu-coated alloy powders showed the best corrosion resistance.
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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.
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