• Title/Summary/Keyword: Multi Nozzle

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Numerical Simulation of Steam Jet Vacuum System in Multi-effect Desalination Plant (다중효용 담수 설비의 증기이젝터 진공장치에 관한 수치해석)

  • Ko, Sang-Cheol;Kim, Yong-Sun;Choi, Du-Youl;Kim, Pil-Hwan
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.3
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    • pp.238-242
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    • 2015
  • A steam jet vacuum system that will be implemented in a multi-effect desalination plant is numerically investigated. The objective of this study is to numerically investigate the performance characteristic of the steam jet vacuum system for the sea water distillation process. The effects of design parameter such as nozzle size and converging duct angle are discussed in order to get a better understanding of flow characteristics inside the steam ejector and subsequently pave the way for more optimum designs. The simulation results have been in good agreement with experimental data and have well reproduced the shock train phenomena of the throat region.

Process Development of Laser Cladding for Weld Inlay Repair of Dissimilar Metal Weld in Reactor Vessel In/Outlet Nozzles (원자로 입출구 노즐 이종금속 용접부 Weld Inlay 레이저 클래딩 공정 개발)

  • Cho, Hong Seok;Jung, Kwang Woon;Mo, Min Hwan;Cho, Ki Hyun;Choi, Dong Chul;Lee, Jang Wook;Cho, Sang Beum
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.11 no.1
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    • pp.53-60
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    • 2015
  • This study was investigated to develop process technology of laser cladding with austenite stainless steel for Weld Inlay repair of dissimilar metal weld in reactor vessel in/outlet nozzles. Weld Inlay experiments were performed by laser cladding repair system consisting of common manipulator, laser apparatus and welding process scheduler, etc. Single pass welding experiments were conducted in order to obtain the optimum welding process parameters for filler wires of ER309L and Alloy 52M before multi-layer laser cladding. Based on the above obtained results, multi-layer laser cladding experiments were carried out, and welding qualities for weld specimens were estimated by PT, OM, SEM and EDS analysis. Consequently, it was revealed that multi-layer laser cladding on austenite stainless steel using filler wires of ER309L and Alloy 52M could be possible to meet ASME Code standard without any weld defect.

Combustion Characteristics and On-site Performance Test of a Double-cone Partial Premixed Nozzle with Various Fuel hole Patterns (이중 콘형 부분예혼합 GT 연료노즐의 연소특성 및 발전플랜트 실증)

  • Kim, Han Seok;Cho, Ju Hyeong;Kim, Min Kuk;Hwang, Jeongjae;Lee, Won June;Min, Kyungwook;Kang, Do Won
    • Journal of the Korean Institute of Gas
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    • v.25 no.6
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    • pp.22-28
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    • 2021
  • Combustion characteristics were examined experimentally for a swirl-stabilized double cone premixed burner nozzle used for industrial gas turbines for power generation. An original model and a variant with a different fuel injection pattern are tested to compare their combustion characteristics such as NOx, CO and stability in pressurized conditions with single burner-flame and in an ambient multi-flame conditions with multi-burners. Test results show that NOx emissions are smaller for the variant, whose number of fuel holes is reduced with the same total area of fuel holes, in ambient and pressurized single-flame conditions with single burner, which results from enhanced fuel/air mixing due to a higher penetration of fuel into the air stream. The multi-burnerflame test results show that NOx emissions are smaller for the variant due to reduced flame interactions, which, on the contrary, slightly reduces the stability margin. On-site test results fromin an actual power plants also show that NOx emissions are reduced for the variant, compared with the original one, which is in agreement with the lab test results stated above.

IDENTIFICATION OF TWO-DIMENSIONAL VOID PROFILE IN A LARGE SLAB GEOMETRY USING AN IMPEDANCE MEASUREMENT METHOD

  • Euh, D.J.;Kim, S.;Kim, B.D.;Park, W.M.;Kim, K.D.;Bae, J.H.;Lee, J.Y.;Yun, B.J.
    • Nuclear Engineering and Technology
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    • v.45 no.5
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    • pp.613-624
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    • 2013
  • Multi-dimensional two-phase phenomena occur in many industrial applications, particularly in a nuclear reactor during steady operation or a transient period. Appropriate modeling of complicated behavior induced by a multi-dimensional flow is important for the reactor safety analysis results. SPACE, a safety analysis code for thermal hydraulic systems which is currently being developed, was designed to have the capacity of multi-dimensional two-phase thermo-dynamic phenomena induced in the various phases of a nuclear system. To validate the performance of SPACE, a two-dimensional two-phase flow test was performed with slab geometry of the test section having a scale of $1.43m{\times}1.43m{\times}0.11m$. The test section has three inlet and three outlet nozzles on the bottom and top gap walls, respectively, and two outlet nozzles installed directly on the surface of the slab. Various kinds of two-dimensional air/water flows were simulated by selecting combinations of the inlet and outlet nozzles. In this study, two-dimensional two-phase void fraction profiles were quantified by measuring the local gap impedance at 225 points. The flow conditions cover various flow regimes by controlling the flow rate at the inlet boundary. For each selected inlet and outlet nozzle combination, the water flow rate ranged from 2 to 20 kg/s, and the air flow rate ranged from 2.0 to 20 g/s, which corresponds to 0.4 to 4 m/s and 0.2 to 2.3 m/s of the superficial liquid and gas velocities based on the inlet port area, respectively.

An Experiment on Heat Dissipation from Aluminum foam Heat Sinks in an Air Multi-Jet Impingement (다중 충돌 공기제트에서 발포 알루미늄 방열기의 방열 특성 실험)

  • Lee, Myeong-Ho;Kim, Seo-Yeong;Lee, Gwan-Su
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.8
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    • pp.1115-1122
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    • 2002
  • The present experiment investigates the effects of pore density f of aluminum foam heat sinks, the jet-to-jet spacing X and the nozzle plate-to-target surface spacing H of 3$\times$3 square impinging arrays on the averaged Nusselt number. The performance of the aluminum foam heat sinks and the rectangular plate heat sink is evaluated in terms of the enhancement factor. /equation omitted/. The multiple impinging jet with X/d=4.0 displays higher Nusselt numbers than single impinging jet for 12.0$\leq$H/d$\leq$20.0. With the variation of the jet-to-jet spacing, the aluminum foam heat sink of 10 PPI show higher Nusselt numbers than the 20 and 40 PPI aluminum foam heat sinks. Further, the 10 PPI aluminum foam heat sink demonstrates 26% higher enhancement factor than the rectangular plate heat sink in the range of 7000$\leq$Re$\leq$11000.

A Study on the Shell Wall Thinning by Flow Acceleration Corrosion and Mitigation Plan and Design Modification of a Feedwater Heater Impingement Baffle (유동가속부식으로 인한 급수가열기 동체 감육현상 규명과 완화 방안 및 충격판 설계개선에 관한 연구)

  • Kim, Kyung-Hoon;Hwang, Kyeong-Mo;Kim, In-Tae
    • Journal of ILASS-Korea
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    • v.15 no.2
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    • pp.83-93
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    • 2010
  • Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damage, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle inside feedwater heater installed downstream of the turbine extraction stream line. At that point, the extract steam from the turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows to reverse direction after impinging the impingement baffle, the shell wall of feedwater heaters may be affected by flow-accelerated corrosion. In this paper, to compare degree of shell wall thinning mitigation rate to squared type with mitigation rate of other type baffle plate, four different types of impingement baffle plate-squared, curved, mitigating type and multi-hole type-applied inside the shell. With these comparison data, this paper describes operation of experiments and numerical analysis which is composed similar condition with real feed water heater. And flow visualization is operated for verification of experiments and numerical analysis. In conclusion, this study shows that mitigating type and multi-hole type baffle plate are more effective than other baffle plate about prevention of pressure concentration and pressure value decrease.

A study on the influence of process parameters during laser welding of sheet steels (강판의 레이저 용접시 공정변수의 영향에 관한 연구)

  • Park, Young-Soo;Lee, Yoon-Sik;Kim, Hyung-Sik;Kim, Chan
    • Laser Solutions
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    • v.2 no.3
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    • pp.11-18
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    • 1999
  • This paper describes the weldability of carbon steel and stainless steel using 5㎾ $CO_2$ laser system with nearly multi-mode beam and a parabolic focusing mirror. In the laser welding of steels, major welding parameters are focal point, travel speed, beam power, shield gas and gap tolerance, etc.. Two kinds of gases(Ar, He) were used as a assist gas and supplied through the external nozzle. It is very important for optimum condition to remove plasma plume which absorbs laser beam and to obtain deep penetration and sound weld bead. Bead-on-plate welding tests were carried out for the experiments. Penetration data were obtained with various welding parameters and the effects of welding parameters were discussed. Butt welding tests were performed with various conditions. Only the optimum laser parameters assured good weld quality As a result of this study, We achieve the fundamental weldabilities using a high power $CO_2$ laser for carbon steel and stainless steel.

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Meanline analysis method for performance analysis of a multi-stage axial turbine in choking region (다단 축류 터빈에서의 초킹 영역 탈설계 성능 해석을 위한 평균반경 해석법)

  • Kim, Sangjo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.881-888
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    • 2017
  • In general, the choking phenomenon occurs by flow acceleration for a turbine at high pressure ratio condition. In choking condition, total pressure ratio increases without mass flow rate variation. It is hard to predict choking characteristics by using conventional meanline analysis which used mass flow inlet boundary condition. In the present study, the algorithm for predicting choking point is developed to solve the problem. Moreover, performance estimation algorithm after choking is presented by reflecting the flow behaviour of flow expansion at choked nozzle or rotor. The analysis results are compared with 3D CFD analysis and experimental data to validate present method.

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Meanline Analysis Method for Performance Analysis of a Multi-stage Axial Turbine in Choking Region (다단 축류 터빈에서의 초킹 영역 탈설계 성능 해석을 위한 평균반경 해석법)

  • Kim, Sangjo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.2
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    • pp.20-28
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    • 2018
  • In general, the choking phenomenon occurs due to the flow acceleration of a turbine under high pressure-ratio. During choking, the total pressure ratio increases without any variation in the mass flow rate. It is difficult to predict choking characteristics by using conventional meanline analysis, which utilizes mass flow inlet boundary condition. In this study, an algorithm for predicting the choking point is developed to solve this problem. In addition, a performance estimation algorithm is presented to estimate the performance after choking, based on the flow behavior of flow expansion at the choked nozzle or rotor. The analysis results are compared with 3D CFD analysis and experimental data to validate this method.

Investigation of MVR and TVR in Chemical Processes by Using Waste Steam (화학공정 내 폐증기를 활용한 MVR 및 TVR 연구)

  • Lee, Chang Min;Lim, Jeong Yeol;Yun, Rin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.4
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    • pp.201-206
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    • 2015
  • The MVR was theoretically modeled by performing the polytropic process, and the polytropic coefficient was estimated by using the performance curve provided by the manufacturers. The TVR was investigated by applying the conservation equations to the movement of fluids inside the TVR. The size of the nozzle and diffuser was determined. Theoretical MVR and TVR modeling was verified by comparing the results of the model with the available design data. Besides, the effects of multi-staging of the MVR on power consumption, and the effects of suction and primary pressure on the sizing of TVR were investigated.