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요철을 가진 2차원 평면에서의 열전달 특성에 대한 수치해석 연구
우주식(Jusik Woo),라빕(Mummad Nuim Labib),최현근(Hyengun Choi),정효민(Hyomin Jeong),정한식(Hanshik Chung) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
The heat transfer characteristics of two-dimensional turbulent with rib have been numerically investigated. The effects of Rib shape(rectangular, triangle) and dimensionless rib height to plate distance to(e/D=0.0667, 0.1333) analysis. To calculate the heat transfer by using commercial software and turbulent model is k-omega SST model. The numerical results have also checked with available theoretical relations good agreements has achieved.
우주식(Jusik Woo),이경환(Kyeonghwan Lee),위보워(Wi bowo),정한식(Hanshik Chung),정효민(Hyomin Jeong) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
In designing of condensers, the prediction of pressure drop is very important to predict the heat transfer coefficient. Modeling of two phase flow, inside a horizontal tube using CFD analysis is difficult with available two phase model in Fluent because of its changing flow patterns continuously. In this paper presents the CFD analysis of two phase flow of refrigerants inside a horizontal tube of 1.2m length three different inner model diameters of 0.085m, 0.0125m and 0.02141m, respectively, is carried out using 3D model under adiabatic condition. The considered refrigerants are R12 and R134a. The analysis is conducted at different temperatures and flow rates to evaluate the local frictional pressure drop. Using 3D model, average properties are obtained for each refrigerants. Obtained pressure drop data is compared with separated flow models available in literature.
사각채널내의 열교환 촉진제의 형상에 따른 영향에 관한 수치해석 연구
정한식(Hanshik Chung),우주식(Jusik Woo),라빕(Muhammad Nuim Labib),전유신(Yousin Chun),정효민(Hyomin Jeong) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회 학술대회 논문집 Vol.2010 No.4
A numerical simulation for studying fluid flow and heat transfer characteristics in a square channels with thermal enhancements are investigated in the present study. The square duct has a length 300㎜ and height 30㎜ square thermal enhancements are attached in the bottom and top walls. The thermal enhancements with different height and shape have been used in the current study. To Calculate the heat transfer, k-omega SST model. The numerical results have also checked with available Theoretical relations Good agreements has achieved.
CFD Investigation of the Flow Phenomena inside the Multistage Mechanical Vapor Compressor
Muhammad Nuim Labib,Jusik Woo(우주식),Duyol Choi(최두열),Hanshik Chung(정한식),Hyomin Jeong(정효민) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Mechanical vapor compressor is a part of steam compressor employed in multi effect distillation process. A greater understanding of flow phenomena inside of mechanical compressor plays an important role when the performance improvement of overall system in MED desalination is necessary. In this paper, the mechanical compressor was numerically investigated to study the influence of operating condition. The steady numerical simulation using k- ε turbulent model with frozen rotor interface was used for multistage centrifugal compressor simulation. In this simulation using three section zones and only single passage on each stage is considered to reduce the computational cost and time consuming. This study is just only focused on the influence of operating pressure. From the simulation result shows a good understanding about the optimum operating condition even though using steady simulation.
FEATURES OF PRESSURES IN THE PIPE FITTED BETWEEN TWO SNUBBERS IN HYDROGEN COMPRESSING SYSTEM
Mohammad Rahman(라흐만),Kyeonghwan Lee(이경환),Suprianto Wobowo(위보워),Jusik Woo(우주식),Hanshik Chung(정효민),i Hk Chung(정한식) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Compressing system is one of the most important processes in hydrogen gas handling: production, storage, distribution until using. High pulsation waveforms produced during hydrogen compression can be reduced by employing snubber in the system. There are some pipes to flow hydrogen between two snubbers. An experiment has been conducted to investigate the features of pressure in the pipe placed between snubbers in reciprocating compression system. In measuring amplitude FFT was done and pressure RMS values at input and output of one the pipe using data for 10, 20, 30, 50 and 60 ㎐ motor frequency of compressor operation. The pressure pulsation reductions are varied from 16.415~35.151% and corresponding pressure losses 0.007~0.759%.