• Title/Summary/Keyword: Coil tube

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Experimental Study on Compact type CO2 Gas Cooler(1) - Heat Flowrate and Pressure Drop in a Multi-Tube-In-Tube Helical Coil Type Gas Cooler - (CO2 가스쿨러용 콤팩트열교환기 개발에 관한 연구(1) -다중관식 헬리컬 코일형 가스냉각기내 CO2의 열유량과 압력강하-)

  • Oh, Hoo-Kyu;Son, Chang-Hyo
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.1
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    • pp.30-36
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    • 2010
  • The heat flowrate and pressure drop of $CO_2$ in a multi-tube-in-tube helical coil type gas cooler were investigated experimentally. The mass flowrate of $CO_2$ and coolant were varied from 0.06 to 0.075 [kg/s], respectively and the cooling pressure of gas cooler were from 8 to 10 [MPa]. The heat flowrate of $CO_2$ in the test section is increased with the increase in mass flowrate of coolant, the cooling pressure and mass flowrate of $CO_2$. The pressure drop of $CO_2$ is decreased with the decrease in mass flowrate of coolant and $CO_2$, but decreased with increase in cooling pressure of $CO_2$. The heat flowrate of $CO_2$ in the multi-tube-in-tube helical coil type gas cooler is greatly higher than that of $CO_2$ in the double pipe type gas cooler, while the pressure drop of $CO_2$ in the multi-tube-in-tube helical coil type gas cooler is greatly lower than that of $CO_2$ in the double pipe type gas cooler. Therefore, in case of the application of $CO_2$ at the multi-tube-in-tube helical coil type gas cooler, it is expected to carry out the high-efficiency, high-performance and compactness of gas cooler.

A Study on Thermo-Hydraulic Analysis for KSTAR(Korea Superconducting Tokamak Advanced Research) Cooling Line System (KSTAR(Korea Superconducting Tokamak Advanced Research) 냉각 시스템에 대한 열해석 연구)

  • Kim, H.W.;Ha, J.S.;Kim, D.S.;Lee, J.S.;Choi, C.H.
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.296-301
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    • 2003
  • A study on the engineering design and numerical thermo-hydraulic analysis for KSTAR TF coil structure cooling system has been conducted. The numerical analyses have been done to verify the engineering design of cooling using the commercial code, FLUENT and in-house code for calculating helium properties which varies with cooling tube's heat transfer. Through the engineering design process based on the steady heat balance concepts, the circular stainless steel tube with inner diameter of 4 mm for TF coil has been selected as cooling tube. From normal operation mode analysis results, total 28 cooling tubes were finally chosen. Also, three dimensional cool down analysis for TF coil with designed cooling tube was satisfied with next three design criteria. First is cooling work termination within a month, second is maximum temperature difference within 50 K in TF coil structure and third is exit helium pressure above 2 bar. Consequently, these cool down scenario results can afford to adopt as operating scenario data when KSTAR facilities operate.

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Numerical analysis of the vertical tube-in-tube ground coil heat exchanger (수직으로 매설된 이중관형 지중 열교환기에 대한 해석적인 연구)

  • 유지오;금성민;신현준
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.3
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    • pp.339-348
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    • 1999
  • A computer model was developed in order to predict the temperature distribution and the performance of the vertical tube-in-tube ground coil heat exchanger. This model has been validated by experimental results conducted by ORNL. The heat exchanger performance with the variation of the length is calculated and compared. As results, the heat exchanger performance is proportional to the length but the performance per unit length decreases. The minimum performance of 70m - PVC heat exchanger during cyclic operation for a week is obtained 20,054kJ/h for cooling operation and 13,915kJ/h for heating operation. And minimum temperature difference is $4.64^{\circ}C$ for cooling operation and $2.64^{\circ}C$ for heating operation. In each case, it is noted that the temperature difference between the pipe and the far-field occurs within 0.8m from the heat exchanger.

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Effect of a Coil Shape on an Impulse Velocity of the Electromagnetic Welding (전자기 용접의 충돌 속도에 대한 코일 형상의 영향)

  • Park, H.;Lee, K.;Lee, J.;Lee, Y.;Kim, D.
    • Transactions of Materials Processing
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    • v.28 no.3
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    • pp.135-144
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    • 2019
  • Electromagnetic impulse welding (EMIW) is a type of solid state welding using the Lorentz force generated by interaction between the magnetic field of the coil and the current induced in the workpiece. Although many experimental studies have been investigated on the expansion and compression welding of tube using the EMIW process, studies on the EMIW process of lap joint between flat sheets are uncommon. Since the magnetic field enveloped inside the tube can be controlled with ease, the electromagnetic technique has been widely used for tube welding. Conversely, it is difficult to control the magnetic field in the flat sheet welding so as to obtain the required welding velocity. The current study analyzed the effects of coil shape on the impulse velocity for suitable flat one-turn coil for the EMIW of the flat sheets. The finite element (FE) multi-physics simulation involving magnetic and structural field of EMIW were conducted with the commercial software LS-DYNA to evaluate the several shape variables, viz., influence of various widths, thicknesses, gaps and standoff distances of the flat one-turn coil on the impulse velocity. To obtain maximum impulse velocity, the flat one-turn coil was designed based on the FE simulation results. The experiments were performed using an aluminum alloy 1050 sheets of 1.0mm thickness using the designed flat one-turn coil. Through the microscopic interfacial analysis of the welded specimens, the interfacial connectivity was observed to have no defects. In addition, the single lap joint tests were performed to evaluate the welding strength, and a fracture occurred in the base material. As a result, a flat one-turn coil was successfully designed to guarantee welding with bond strength equal to or greater than the base material strength.

Ice Making Characteristics according to Shape and Diameter on Ice-on-Coil Tube (관외착빙형 제빙관의 형태 및 관경 변화에 따른 제빙 특성)

  • Park, K.W.;Jeong, E.H.;Hwang, S.S.
    • Journal of Power System Engineering
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    • v.16 no.5
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    • pp.32-39
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    • 2012
  • The study experimented to understand ice-on-coil type ice making characteristics on to 3 kinds of circular tube, oval tube and small diameter tube using ice maker. The experiment were carried out under various conditions, that used brine temperature($-10^{\circ}C$, $-6^{\circ}C$), brine flow rate(1.0m/s, 1.8m/s) and inlet water temperature ($6^{\circ}C$, $12^{\circ}C$) etc. Mass of ice per ice making area increased according to the decrease of the brine temperature and inlet water temperature, but that was increased according to the increase of the brine flow rate. Oval ice making tube produced ice 1.11 to 2.46 times that of 9mm circular ice making tube, and 3mm small diameter ice making tube produced ice 1.06 to 1.51 times that of 9mm circular ice making tube.

Evaporation Heat Transfer Characteristics of Liquid Nitrogen in Horizontal Plain Tubes with Wire Coil Inserts (평활관 및 열전달촉진관에서 액체질소의 관내 증발열전달 특성에 대한 연구)

  • Hwang, Jee-Sang;Chung, Jin-Taek;Yun, Rin;Kim, Yong-Chan;Moon, Young-June;Kim, Dong-Hyuk
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1359-1364
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    • 2004
  • An experiment was performed to study the evaporation heat transfer and the pressure drop characteristics of liquid nitrogen in a horizontal stainless steel tube with wire coil inserts. The inner diameter of test tube is 4.3mm and the length is 1.5m. Four wire coils having different pitch and thickness were inserted into the plain test tube. The wire coil length is 1.5m and the diameter is 3.65mm with thickness of 0.5mm and 0.9mm. Experiments were conducted at saturation temperature of $-191^{\circ}C$ mass flux from 200 to 370 $kg/m^{2}s$ and heat flux of 62 $kW/m^{2}$. Direct heating method was used to apply heat to the test section. Boiling heat transfer coefficients of both the plain and the enhanced tubes were calculated. Pressure drops between inlet and outlet side of test section were also measured, and they are used to estimate EPR(Enhancement Performance Ratio).

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Flow Boiling Heat Transfer Characteristics of Liquid Nitrogen in Plain and Wire Coil Inserted Tubes (평활관 및 와이어코일을 삽입한 열전달촉진관에서 액체질소의 흐름비등열전달 특성)

  • Hwang Jee-Sang;Yun Rin;Kim Yongchan;Chung Jin Taek
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.8 s.239
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    • pp.927-933
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    • 2005
  • Boiling heat transfer characteristics of liquid nitrogen in a stainless steel plain tube and wire coil inserted tubes were investigated. The test tubes, which had an inner diameter of 10.6 m and a length of 1.65 m, were horizontally located. Five wire coils having different pitch and thickness were inserted into the plain tube. The pitches of the wire coils were 18.4, 27.6, and 36.8 m, and the thickness was 1.5, 2.0, and 2.5 mm respectively. Tests were conducted at a saturation temperature of $-191^{\circ}$, mass fluxes from 58 to 105 kg/$m^2s$, and heat fluxes from 22.5 to 32.7 kw/$m^2$. A direct heating method was used to apply heat to the test section. The boiling heat transfer coefficients of liquid nitrogen were represented as a function of vapor quality, which showed significant drop at the dryout vapor quality. The maximum heat transfer enhancement using the wire coil inserted tubes over the plain tube was $174\%$ for 'Wire 3' having a thickness of 2.5 mm and a pitch of 18.4 mm.

Experimental Study on Heat Transfer and Pressure Drop of Heat Exchangers for Cooling Fan Coil Unit (냉방용 팬코일 유닛 열교환기의 열전달 및 압력강하 특성 실험연구)

  • Kwon, Young-Chul;Ko, Kuk-Won;Kwon, Jeong-Tae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.9 no.3
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    • pp.599-604
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    • 2008
  • An experimental study has been performed to investigate the air-side capacity and pressure drop of the fin-tube heat exchanger for a fan coil unit under a cooling condition. The experimental data of five kinds of slit fin-tube heat exchangers were measured using an air-enthalpy calorimeter and a constant temperature water bath. Cooling capacities at the air and water rating flow rates were larger at the lower inlet water temperature. With increasing the water flow rate, the cooling capacity increased at the constant rate. Under the lower inlet water temperature, since the condensate was generated more on the fin-tube surface, the air-side pressure drop of the heat exchanger was larger.

Heat Transfer Characteristics of Carbon Dioxide in a Inclined Helical Coil Type Heat Exchanger with Inner Diameter Tube of 4.55 mm (내경 4.55 mm의 경사진 헬리컬 코일형 열교환기내 이산화탄소의 열전달 특성에 관한 연구)

  • Son, Chang-Hyo
    • Journal of the Korean Institute of Gas
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    • v.11 no.3
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    • pp.1-6
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    • 2007
  • The heat transfer coefficient and pressure drop during gas cooling process of $CO_2$ (R-744) in inclined helical coil copper tubes were investigated experimentally. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and a inclined helical coil type gas cooler (test section). The test section consists of a smooth copper tube, which is specified as the inner diameter of 4.55 mm. The refrigerant mass fluxes were varied from 200 to $600kg/m^2s$ and the inlet pressures of gas cooler were done 7.5 to 10.0 (MPa). The heat transfer coefficients of $CO_2$ in the inclined helical coil tubes increase with the increase of mass flux and gas cooling pressure of $CO_2$. The pressure drop of $CO_2$ in the gas cooler shows relatively good coincidence with those predicted by Ito's correlation developed for single-phase in a helical coil tube. The local heat transfer coefficient of $CO_2$ is well coincident with the correlation by Pitla et al. However, at the region near pseudo-critical temperature, the experiments indicate higher values than the Pitla et al. correlation.

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Signal Analysis of Eddy Current Test Using T/R Coil Probe for Inspection of Steam Generator Tube in NPP (T/R코일프로브를 이용한 원전 SG세관 검사의 와전류탐상 신호해석)

  • Lim, Geon-Gyu;Lee, Hyang-Beom
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.4
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    • pp.159-165
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    • 2008
  • In this paper the signal analysis of eddy current test using transmit-receive(T/R) pancake coil of ECT array probe using electromagnetic finite element method(FEM) is performed. For characteristics analysis, the notch defect is used. The depth of defect is 40[%] of steam generator tube thickness, and inside defect and outside defect are used as simulation examples. The signal analysis is performed according to the variation of receive coil position. The receive coil is positioned $0[^{\circ}]$, $30[^{\circ}]$, $60[^{\circ}]$, $90[^{\circ}]$ of circumferential position of transmit coil. To obtain e electromagnetic characteristics of robes, the governing equation is derived from Maxwell's equations, and the problem is solved using the 3-dimensional finite element method. The signal magnitude of inside defect is bigger than that of outside defect, and the signal difference can be seen according to the variation of position of receive coil. The experimental signal and numerical signal of ASME standard tube show similar results. The results in this paper can be helpful when the ECT signals from ECT array probe are evaluated and analyzed.