• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2319-2324
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• 2003

This paper addresses the optimal design of dividing wall distillation column which is rapidly applied in a variety of chemical processes over recent several years because of its high energy saving efficiency. A general dividing wall column model which can cope with the heat transfer through the dividing wall is developed using rigorous computer simulation. Based on the simulation model, the effects of the internal recycle flow distribution around the dividing wall and the heat transfer across the dividing wall on overall system performance are investigated. An improved method is suggested to utilize the heat transfer through the wall to optimal column design. The suggested method is compared with the existing method via. simulation study and shows more improved energy saving result. Several control strategies for the divided wall column are tested and the optimal control strategy is propose

• Journal of Advanced Marine Engineering and Technology
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• 제34권7호
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• pp.981-990
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• 2010

The main objective of this study is to investigate the fluid flow and the heat transfer characteristics of nanofluids using multi-phase thermal LBM and to realize theenhancement of heat transfer characteristics considered in the Brownian motion. In multi-phase, fluid component($H_2O$) is driven by Boussinesq approximation, and nanoparticles component by the external force gravity and buoyancy. The effect of Brownian motion as a random movement is modified to the internal velocity of nanoparticles(Cu). Simultaneously, the particles of both the phases assume the local equilibrium temperature after each collision. It has been observed that when simulating $H_2O$-Cu nanoparticles, the heat transfer is the highest, at the particle volume fraction 0.5% of the particle diameter 10 nm. The average Nusselt number is increased approximately by 33% at the particle volume fraction 0.5% of the particle diameter 10 nm when compared with pure water.

• 제어로봇시스템학회논문지
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• 제9권3호
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• pp.236-241
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• 2003

This paper addresses the optimal design of dividing wall distillation column which is rapidly applied in a variety of chemical processes over recent several years because of its high energy saving efficiency. A general dividing wall column model which can cope with the heat transfer through the dividing wall is developed using rigorous computer simulation. Based on the simulation model, the effects of the internal recycle flow distribution around the dividing wall and the heat transfer across the dividing wall on overall system performance are investigated. An improved column design method is suggested to utilize the heat transfer through the wall. The suggested method is compared with the existing method via simulation study in which the proposed design shows improved energy saving result.

• 설비공학논문집
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• 제11권6호
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• pp.740-748
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• 1999

This research was concerned with the enhancement of heat transfer by surfactant added to the aqueous solution of LiBr. Different vertical tubes were tested with and without an additive of normal octyl alcohol. The test tubes were a bare inner surface, groove inner surface, corrugated inner surface and spring inserted inner surface tubes. The additive concentration was about 0.08 mass%. The heat transfer coefficient was measured as a function of film Reynolds number in the range of 20~200. Experiments were tarried out at higher cooling water temperature of $35^{\circ}C$ to simulate an air cooling condition for several kinds of absorber testing tubes. The experimental results were compared with cases without surfactant. The enhancement of heat transfer by Marangoni convection effect which was generated by addition of the surfactant is observed in each test tube. Especially, it is clarified that the tube with an inserted spring has the highest enhancement effect.

• 공업화학
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• 제19권1호
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• pp.73-79
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• 2008

본 연구에서는 핀-관 열교환기의 공기측 열전달, 마찰 그리고 물질특성을 조사하기 위하여 6종의 열교환기에 대하여 습조건에서 실험을 수행하였다. 실험에 사용된 핀은 루버형으로 핀피치, 관 열수 그리고 입구상대습도를 변화하였다. 루버핀-관 열교환기의 열전달계수와 마찰계수는 레이놀즈 수가 증가할수록 감소하였으며, 핀피치가 줄어들수록 열전달계수는 감소하였고 마찰계수는 증가하였다. 3열 열교환기의 열전달계수와 마찰계수의 핀피치 변화에 따른 영향은 2열 열교환기의 경우보다 덜 민감하였다. 그리고 유입공기의 상대습도에 대한 열전달계수와 마찰계수의 변화폭은 크지 않았다. 또한, 루버핀-관 열교환기의 물질전달계수는 핀피치가 감소할수록 줄어들었으나, 레이놀즈 수 변화에 따른 물질전달계수는 열전달계수와는 달리 관 열수에 따라 서로 다른 경향을 보였다. 유입공기의 상대습도가 높아질수록, 물질전달계수는 다소 줄어 들었다.

• 설비공학논문집
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• 제21권2호
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• pp.79-86
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• 2009

The present study was investigates the effect of the parameters on the frost formation and heat transfer performance such as fin shape, air temperature and air velocity. Heat transfer rate and pressure drop by frost were experimentally investigated. Effect of the wet blub temperature and air velocity on the heat transfer performance has been also investigated. The heat transfer performance of the louver fin and tube type heat exchanger was higher by maximum of 0.85% than the corrugate fin type at the air temperature of $2.0/1.5^{\circ}C$. As the wet blub temperature of air were increased, the heat transfer rate, pressure drop and mass of frost of three test models were increased. Especially, the maximum heat transfer rate and maximum pressure drop were shown for the Type B louver fin heat exchanger. As an experimental result, the enhancement factor(EF) of louver fin and tube type heat exchanger was only $0.2{\sim}0.4$ due to the high pressure drop.

• 대한설비공학회지:설비저널
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• 제15권3호
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• pp.273-282
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• 1986

The purpose of this research was to study the characteristics of heat transfer in Heat Pipe which used the composition wick of screened groove - metallic mesh by ADI method and experimental results. As the results, the more than number of metallic mesh screen layers in a heat pipe increased, the fewer the effect of heat recovery decreased. In case of 1 - layer metallic mesh screen wick, the response of the effect in heat recovery was more rapidly showed than in case of other layers and in spite of high load, the evaporation section of Heat pipe with 1 - layer metallic mesh screen wick showed the stable response and did not show excessive super heat. There was a interrelation between thermal resistance and the variable layers, between thermal resistance and the variable gaps of metallic meshes, the heat transfer characteristics of Heat pipe were depended on the thermal resistance of composition wick.

• 대한기계학회논문집B
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• 제30권4호
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• pp.328-336
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• 2006

Detailed heat transfer coefficient distributions an two. types of gas turbine blade tip, plane tip and squealer tip, were measured using a hue-detection base transient liquid crystals technique.. The heat transfer coefficients an the shroud and near tip regions of the pressure and suction sides af the blade were also. measured. The heat transfer measurements were taken at the three different tip gap clearances af 1.0%, 1.5%, and 2.5% of blade span. Results shaw the overall heat transfer coefficients on the tip and shroud with squealer tip blade were lower than those with plane tip blade. By using squealer tip, however, the reductions af heat transfer coefficients near the tip regions of the pressure and suction sides were nat remarkable.

• 한국분무공학회지
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• 제19권1호
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• pp.15-18
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• 2014

In the present study, experiment on the evaporation of pure water droplet on heated surface was conducted, and the evaporative heat transfer coefficients were calculated from experimental results. The pure water droplet of about $10{\mu}l$ was applied onto the heat transfer surface, then the shape of the droplet was analyzed during the evaporation. In addition, the effect of surface roughness on the evaporative heat transfer was also investigated. Experimental results showed that the evaporative heat transfer coefficients increased rapidly along with the increase of surface temperature and the heat transfer coefficients increased with the increase of surface roughness.

• Journal of Advanced Marine Engineering and Technology
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• 제26권1호
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• pp.83-89
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• 2002

In the present study, heat transfer characteristics of oil flow over offset strip fins were predicted by the numerical methods. Oil flow in the plate-fin passage was idealized by 2 dimensions. The flow patterns and heat transfer characteristics were predicted in details. Numerical results shows that the average convective heat transfer coefficients are almost independent on the raws of fins and affected by fin pitches. At the rear face of fin, there exists minimum point of heat transfer coefficients where stream are separated from the fin surfaces. The convective heat transfer coefficients were effected by separation bubbies which appeared at the wake region of offset strip fins.