Experimental research and numerical simulation on cryogenic line chill-down process

Jin, Lingxue,Cho, Hyokjin,Lee, Cheonkyu,Jeong, Sangkwon Elsevier 2018 Cryogenics Vol.89 No.-

<P>The empirical heat transfer correlations are suggested for the fast cool down process of the cryogenic transfer line from room temperature to cryogenic temperature. The correlations include the heat transfer coefficient (HTC) correlations for single-phase gas convection and film boiling regimes, minimum heat flux (MHF) temperature, critical heat flux (CHF) temperature and CHF. The correlations are obtained from the experimental measurements. The experiments are conducted on a 12.7 mm outer diameter (OD), 1.25 mm wall thickness and 7 m long stainless steel horizontal pipe with liquid nitrogen (LN2). The effect of the lengthwise position is verified by measuring the temperature profiles in near the inlet and the outlet of the transfer line. The newly suggested heat transfer correlations are applied to the one-dimensional homogeneous transient model to simulate the cryogenic line chill-down process, and the chill-down time and the cryogen consumption are well predicted in the mass flux range from 26.0 kg/m(2)s to 73.6 kg/m(2)s through the correlations.</P>

ICEC 25- ICMC 2014 참관기

Lingxue Jin 한국초전도저온학회 (구 한국초전도저온공학회) 2014 초전도와 저온공학 Vol.16 No.2

Prediction of the effective thermal conductivity of microsphere insulation

Lingxue Jin,Jiho Park,Cheonkyu Lee,Mansu Seo,Sangkwon Jeong 한국초전도저온학회 (구 한국초전도저온공학회) 2014 초전도와 저온공학 Vol.16 No.1

중이온가속기 액체헬륨 분배시스템 보호계통 개발

Jin Lingxue,박미정(M. J. Park),최용준(Y. J. Choi),김무상(M. S. Kim),김용학(Y. H. Kim),박희철(H. C. Park) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

The rare isotope accelerator complex for on-line experiments (RAON) is under construction in Daejeon, Republic of Korea. The cavities of the accelerators are operated at 4.5 K (22 of QWR) and 2.05 K (104 of HWR), which are cooled by liquid helium. The liquid helium is supplied to each cavity through a helium distribution system which controls the physical parameters such as pressure, temperature, liquid helium level, and mass flow rate through the cryogenic valves. This paper describes the design of the protection strategies for the cryogenic system by considering the thermal fluid properties of liquid helium and the construction of the control system for realizing the protection logic. This work will be helpful to the field engineers in providing the methodology to control a complex cryogenic system with various thermal operating conditions.

중이온가속기 액체헬륨 분배시스템 보호계통 개발

Jin Lingxue,박미정(M. J. Park),최용준(Y. J. Choi),김무상(M. S. Kim),김용학(Y. H. Kim),박희철(H. C. Park) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

The rare isotope accelerator complex for on-line experiments (RAON) is under construction in Daejeon, Republic of Korea. The cavities of the accelerators are operated at 4.5 K (22 of QWR) and 2.05 K (104 of HWR), which are cooled by liquid helium. The liquid helium is supplied to each cavity through a helium distribution system which controls the physical parameters such as pressure, temperature, liquid helium level, and mass flow rate through the cryogenic valves. This paper describes the design of the protection strategies for the cryogenic system by considering the thermal fluid properties of liquid helium and the construction of the control system for realizing the protection logic. This work will be helpful to the field engineers in providing the methodology to control a complex cryogenic system with various thermal operating conditions.

Prediction of the effective thermal conductivity of microsphere insulation

Lingxue Jin,박지호,이천규,서만수,정상권 한국초전도.저온공학회 2014 한국초전도저온공학회논문지 Vol.16 No.1

Since glass microsphere has high crush strength, low density and small particle size, it becomes alternative thermal insulation material for cryogenic systems, such as storage and transportation tank for cryogenic fluids. Although many experiments have been performed to verify the effective thermal conductivity of microsphere, prediction by calculation is still inaccurate due to the complicated geometries, including wide range of powder diameter distribution and different pore sizes. The accurate effective thermal conductivity model for microsphere is discussed in this paper. There are four mechanisms which contribute to the heat transfer of the evacuated powder: gaseous conduction (kg), solid conduction (ks), radiation (kr) and thermal contact (kc). Among these components, kg and ks were calculated by Zehner and Schlunder model (1970). Other component values for kc and kr, which were obtained from experimental data under high vacuum conditions were added. In this research paper, the geometry of microsphere was simplified as a homogeneous solid sphere. The calculation results were compared with previous experimental data by R. Wawryk (1988), H. S. Kim (2010) and the experiment of this paper to show good agreement within error of 46%, 4.6% and 17% for each result

Experimental investigation on line chill-down process by liquid argon

Jin, Lingxue,Cho, Hyokjin,Jeong, Sangkwon Elsevier 2019 Cryogenics Vol.97 No.-

<P><B>Abstract</B></P> <P>The cryogenic line chill-down process is an essential part of the cryogenic system application. As the heat transfer characteristics during the transient cooling down are highly affected by the fluid properties, universal heat transfer correlations, which are valid for the chill-down process with various kinds of cryogenic fluid, are required in many industries. This paper investigates cryogenic line chill-down process by using a 7 m long stainless steel horizontal pipe. Liquid argon is selected as the working fluid to examine the fluid property effects. The histories of the wall temperature, pressure, and mass flow rate are measured during the chill-down process. The heat transfer characteristics of liquid argon are analyzed and compared with those of chill-down process with liquid nitrogen. At the same time, the empirical correlations for the critical heat flux, critical heat flux temperature, and minimum heat flux temperature, which can well estimate the parameters for both of liquid nitrogen and liquid argon cases, are suggested. As a result, the critical heat flux is estimated with the mean absolute error (MAE) of 14.8%. The critical heat flux temperature and minimum heat flux temperature are predicted with the MAE of 3.4% and 1.9%, respectively. The empirical correlations are essential to construct a numerical model for simulating the cryogenic line chill-down process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Experimental investigation is performed for the liquid argon line chill-down process. </LI> <LI> The heat transfer characteristics are compared with those in liquid nitrogen cases. </LI> <LI> Empirical correlations for important parameters are suggested. </LI> </UL> </P>

Experimental investigation of line chill-down process with liquid oxygen

Jin, Lingxue,Lee, Jisung,Jeong, Sangkwon IOP Publishing 2019 IOP conference series. Materials science and engin Vol.502 No.-

Prediction of the effective thermal conductivity of microsphere insulation

Jin, Lingxue,Park, Jiho,Lee, Cheonkyu,Seo, Mansu,Jeong, Sangkwon 한국초전도저온공학회 2014 한국초전도저온공학회논문지 Vol.16 No.1

Since glass microsphere has high crush strength, low density and small particle size, it becomes alternative thermal insulation material for cryogenic systems, such as storage and transportation tank for cryogenic fluids. Although many experiments have been performed to verify the effective thermal conductivity of microsphere, prediction by calculation is still inaccurate due to the complicated geometries, including wide range of powder diameter distribution and different pore sizes. The accurate effective thermal conductivity model for microsphere is discussed in this paper. There are four mechanisms which contribute to the heat transfer of the evacuated powder: gaseous conduction ($k_g$), solid conduction ($k_s$), radiation ($k_r$) and thermal contact ($k_c$). Among these components, $k_g$ and $k_s$ were calculated by Zehner and Schlunder model (1970). Other component values for $k_c$ and $k_r$, which were obtained from experimental data under high vacuum conditions were added. In this research paper, the geometry of microsphere was simplified as a homogeneous solid sphere. The calculation results were compared with previous experimental data by R. Wawryk (1988), H. S. Kim (2010) and the experiment of this paper to show good agreement within error of 46%, 4.6% and 17 % for each result.

Experimental investigation of heat transfer coefficient of mini-channel PCHE (printed circuit heat exchanger)

Kwon, Dohoon,Jin, Lingxue,Jung, WooSeok,Jeong, Sangkwon Elsevier 2018 Cryogenics Vol.92 No.-

<P><B>Abstract</B></P> <P>Heat transfer coefficient of a mini-channel printed circuit heat exchanger (PCHE) with counter-flow configuration is investigated. The PCHE used in the experiments is two layered (10 channels per layer) and has the hydraulic diameter of 1.83 mm. Experiments are conducted under various cryogenic heat transfer conditions: single-phase, boiling and condensation heat transfer. Heat transfer coefficients of each experiments are presented and compared with established correlations. In the case of the single-phase experiment, empiricial correlation of modified Dittus-Boelter correlation was proposed, which predicts the experimental results with 5% error at Reynolds number range from 8500 to 17,000. In the case of the boiling experiment, film boiling phenomenon occurred dominantly due to large temperature difference between the hot side and the cold side fluids. Empirical correlation is proposed which predicts experimental results with 20% error at Reynolds number range from 2100 to 2500. In the case of the condensation experiment, empirical correlation of modified Akers correlation was proposed, which predicts experimental results with 10% error at Reynolds number range from 3100 to 6200.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermal performance of a mini-channel PCHE under cryogenic condition is studied. </LI> <LI> Single-phase, boiling and condensation experiments are conducted. </LI> <LI> Empirical heat transfer correlations are proposed at each experimental condition. </LI> </UL> </P>