• The KSFM Journal of Fluid Machinery
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• 제7권4호
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• pp.47-52
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• 2004

Cryogenic pump test facility (CPTF) is designed and developed in KARI. Hydraulic and cavitation performance of pump and inducer in cryogenic environment can be measured. Working fluid is liquid nitrogen and operating temperature is $-197^{\circ}C$. Run tank, catch tank of liquid nitrogen and their pressurizing tank has been built and remote tank pressure control system are installed. Maximum power of driving motor is 320 kW and its maximum speed is 32000rpm. Cryogenic fluids and lubricating systems are effectively separated that long test times are acquired. Therefore hydraulic and cavitation performance can be measured accurately and effectively. Pre-cooling test of the facility was successfully accomplished. This facility will contribute greatly to the development of turbopump for KSLV.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.340-345
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• 2003

Cryogenic turbopump test facility(CTTF) is designed and developed. Hydraulic and cavitation performance of turbopump in cryogenic environment can be measured. Working fluid is liquid nitrogen and operating temperature is $-197^{\circ}C$. Liquid nitrogen run tank, catch tank and pressurizing tank has been built and remote tank pressure control system are installed. Maximum power of turbopump is 320kW and its maximum speed is 32000rpm. Cryogenic fluids and lubricating systems are effectively separated that long test times are acquired. Therefore hydraulic and cavitation performance can be measured accurately and effectively. This facility will contribute greatly to the development of turbopump for KSLV.

• Transactions of the Korean hydrogen and new energy society
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• 제34권6호
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• pp.741-747
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• 2023

In this study, the heat transfer characteristics were numerically analyzed to investigate the possibility of utilizing cooling water using liquid nitrogen. From the study, as the mass flow rate of the hot fluid increased, the heat transfer rate increased by 8.9-81.7%. And lowering the inlet temperature of the hot fluid resulted in increase in the heat transfer rate by 33.8-71.5%. As for the filling level of liquid nitrogen, as higher filling level led to a decrease in the outlet temperature and an increase in the overall heat transfer coefficient.

• Journal of Advanced Marine Engineering and Technology
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• 제32권5호
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• pp.724-729
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• 2008

Umbilical cord blood has been recently considered an attractive potential alternative as a source of stem cell transplantation to curing diseases such as leukemia, cancers, immune disorders. Normally the stored system of the umbilical cord blood specimen is equipped with a computer-controlled robotic arm that enables the samples to locate the identification places in liquid nitrogen tank at regulated temperature as about $-196^{\circ}C$. As the half of robotic arm is in the air and the rest part is submerged in liquid nitrogen, the temperature of robotic arm varies from ambient to liquid nitrogen temperature. In this study the temperature variation of upper part of arm above tank lid was thermally analysed by using the commercial code of Ansys. The result of analysis was that the upper part of robotic arm was seriously frozen due to heat transfer from liquid nitrogen as low as -$120^{\circ}C$. In order to solve the frost problem of robotic arm, small PTFE tube block as resistance material was introduced into the lower part of tank lid instead of the whole stainless steel(SUS) robotic arm. The results showed that the temperature of robotic arm above the lid was higher enough, and this method would be one of the very effective measure to solve the problem.

• Progress in Superconductivity and Cryogenics
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• 제8권1호
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• pp.65-70
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• 2006

Transient heat transfer caused by an impulsive heating in subcooled liquid nitrogen is investigated experimentally. This study is part of out ongoing efforts directed to a stable cryogenic cooling system lot superconducting fault current limiters (SFCL). A thin heater attached by epoxy on one surface of a GFRP plate is immersed in liquid-nitrogen bath at temperatures between 77 K and 55 K. A strong heat flux up to $150W/cm^2$ is generated lot 100 ms, and the temperature of the heater sulfate is measured as a function of time. The behavior of bubbles on the heating surface can be explained by comparing the measured temperature history for vertical and two horizontal (up and down) orientations. It is concluded that the subcooling of liquid nitrogen below 70 K is very effective in suppressing bubbles, resulting in better thermal protection and faster recovery from an impulsive heat.

• Journal of the Korean Society of Propulsion Engineers
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• 제15권2호
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• pp.56-61
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• 2011

Performance test of a full-scale turbopump assembly for a 75 ton class liquid rocket engine was carried out at full speed. Model fluid was used as a working medium: liquid nitrogen for the oxidizer pump, water for the fuel pump, and hot air for the turbine. The turbopump was operated stably, satisfying the performance requirements. Head coefficient and flow coefficient of the pumps remained constant at the speed-increasing period. In terms of performance characteristics of pumps and turbine, the results from the turbopump assembly test showed a good agreement with those from the turbopump component tests.

• Journal of the Korean Society of Propulsion Engineers
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• 제20권6호
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• pp.91-100
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• 2016

Efficiency characteristics of centrifugal turbopumps for a liquid rocket engine were investigated. Predicting the performance of pumps for a turbopump assembly test, the variation on pump efficiency by working fluids was analyzed from pump component tests. Water and liquid nitrogen (LN2) were used for the component test, kerosene (Jet A-1) and liquid oxygen (LOX) were adapted for the turbopump assembly (TPU) test as working fluids. Overall performance of the pumps was investigated covering design/off-design operating points and the pump efficiency on the environment of real media (LOX/kerosene) could be modified from the pump component tests.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.27-32
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• 2010

Performance test of a full-scale turbopump assembly for a 75 ton class liquid rocket engine was carried out at full speed. Model fluid was used as a working medium: liquid nitrogen for the oxidizer pump, water for the fuel pump, and hot air for the turbine. The turbopump was operated stably, satisfying the performance requirements. Head coefficient and flow coefficient of the pumps remained constant at the speed-increasing period. In terms of performance characteristics of pumps and turbine, the results from the turbopump assembly test showed a good agreement with those from the turbopump component tests.

• Journal of the Korean Society of Propulsion Engineers
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• 제24권3호
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• pp.59-70
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• 2020

Obtaining external forced convection heat transfer from bubble boiling and validating it with experimental results using cryogenic liquids are suggested to derive total heat transfer coefficient with pool boiling condition in the case of coil type heat exchanger with a bundle of tubes and to overcome the limitation of using the empirical correlation. Experiment is conducted with pool boiling heat transfer of saturate liquid nitrogen with helical coil type heat exchanger using liquid oxygen as hot stream fluid. Experimentally measured heat transfer coefficient is well-agreed with the estimated curve considering nucleate boiling and forced convection induced by bubble rise.

• Journal of the Korean Society for Precision Engineering
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• 제10권2호
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• pp.138-145
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• 1993

The bath cryostat of cryogenic apparatuses which are generally used to study physical phenomena under low temperature and ultra low temperature has been desigened and constructed. The practical use of the cryostat is verified by the measurement of the storage life of liquid heloum and liquid nitrogen vessels. The cryostat consists of triple structure of high vacuum environment in order to minimize the evaporation rate of liquid helium and liquid nitrogen by thermal conductivity and radiant heat. The minimum thickness which can stand against inner and outer pressures is calculated from considering the strength of the material.