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Shape Optimization of a Microchannel Heat Sink with Phase Change
Heo, Man Woong,Choi, Dae Woong,Kim, Kwang Yong Trans Tech Publications, Ltd. 2013 Applied mechanics and materials Vol.284 No.-
<P>Optimization of a microchannel heat sink has been performed based on the analyses of fluid flow and heat transfer with phase change using three-dimensional Reynolds-averaged Navier-Stokes equations. The uniform heat flux condition is applied at the bottom of the heat sink. Three design variables, viz. ratio of microchannel width to height of the heat sink, ratio of fin height to heat sink height, and ratio of fin width to height of the heat sink are selected for the shape optimization. Latin hypercube sampling was used to determine the training points as a design of experiment, and the surrogate model is constructed using the objective function values at the training points. Sequential quadratic programming is used to search for the optimal point from the constructed surrogate model. The thermal resistance is set as the objective function. It was found that the thermal resistance increased with increasing ratios of the microchannel width-to-height of the heat sink and fin height to heat sink height, while the thermal resistance decreased with increasing ratio of the fin width-to-height of the heat sink. Through the optimization, the thermal resistance has been decreased by 37.3% compared to the reference geometry.</P>
High-efficiency design of a mixed-flow pump using a surrogate model
Man-Woong Heo,김광용,Jin-Hyuk Kim,Young Soek Choi 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.2
In the present work, the fluid flow characteristics of a mixed-flow pump have beenwere investigated numerically using threedimensional Reynolds-averaged Navier-Stokes equations. The shear stress transport turbulence model and hexahedral grid system were used to analyze the flow in the mixed-flow pump. The efficiency of the mixed-flow pump was evaluated using the variation of two geometric variables related to the inlet angle of the diffuser vane. The design optimization of the mixed-flow pump was performed to maximize the its efficiency at the prescribed specific speed using a surrogate model. Latin hypercube sampling was used to determine the training points for the design of the experiment, and the surrogate model was constructed using the objective function values at the training points. The results show that the efficiency of the mixed-flow pump at the prescribed specific speed is improved considerably by the design optimization.
EFFECTS OF AN EXHAUST HEAT RECOVERY SYSTEM ON PERFORMANCE CHARACTERISTICS OF A FORKLIFT TRUCK
Man-Woong Heo,Suk Jung Bae,Joo-Yeong Jeong,Han-Sung Yoo,Seung Uk Park,Hyung-Seok Heo 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.3
Construction equipment has consumed a lot of energy with a high workload compared to commercial vehicles of the same class. So, fuel efficiency is one of the important indicators of merchantability of the construction equipment. Especially, because forklift has been generally used only when necessary, the work has been carried out without adequate warm-up. So, not only the thermal efficiency of the engine of the construction equipment has deteriorated but also the sufficient fluidity of auto transmission fluid and hydraulic fluid have been hardly able to secure. Therefore, the exhaust heat recovery (EHR) system which consists of exhaust heat recovery unit and auto-transmission fluid (ATF) heater has been developed to improve the fuel economy of forklift by recovering the waste heat of exhaust gas. The performance tests of a 4.5 ton forklift have been carried out to evaluate the effects of exhaust heat recovery system on the fuel economy under the VDI fuel consumption drive cycle. It has found that the fuel consumption of a 4.5 ton forklift can be reduced through the fast warmup of the auto-transmission fluid by recovering the waste heat of exhaust gas.
Design Optimization of a Centrifugal Fan with Splitter Blades
Heo, Man-Woong,Kim, Jin-Hyuk,Kim, Kwang-Yong Walter de Gruyter GmbH 2015 International journal of turbo & jet-engines Vol.32 No.2
<B>Abstract</B><P>Multi-objective optimization of a centrifugal fan with additionally installed splitter blades was performed to simultaneously maximize the efficiency and pressure rise using three-dimensional Reynolds-averaged Navier-Stokes equations and hybrid multi-objective evolutionary algorithm. Two design variables defining the location of splitter, and the height ratio between inlet and outlet of impeller were selected for the optimization. In addition, the aerodynamic characteristics of the centrifugal fan were investigated with the variation of design variables in the design space. Latin hypercube sampling was used to select the training points, and response surface approximation models were constructed as surrogate models of the objective functions. With the optimization, both the efficiency and pressure rise of the centrifugal fan with splitter blades were improved considerably compared to the reference model.</P>
Optimization of a regenerative blower to enhance aerodynamic and aeroacoustic performance
Man-Woong Heo,Tae-Wan Seo,Hyeon-Seok Shim,김광용 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.3
A multi-objective optimization was performed to simultaneously enhance the aerodynamic and aeroacoustic performance of a side channel-type regenerative blower. The aerodynamic characteristics of the regenerative blower were investigated numerically using threedimensional steady and unsteady Reynolds-averaged Navier-Stokes analysis with a shear stress transport turbulence model. On the basis of the aerodynamic sources extracted from the unsteady flow calculation, three-dimensional aeroacoustic analysis was implemented using a finite/infinite element method by solving the variational formulation of Lighthill’s analogy. Three design variables, viz., the ratio of blade height to impeller diameter, ratio of blade width to impeller diameter, and angle between inlet and outlet port, were selected as design variables, and the efficiency and sound pressure level at the design point of the blower were selected as objective functions for the optimization. These two objective functions were estimated numerically through three-dimensional aerodynamic and aeroacoustic analyses at the design points sampled by Latin hypercube sampling in the design space. Pareto-optimal solutions were obtained using a hybrid multi-objective evolutionary algorithm coupled with radial basis neural network models as surrogates of the objective functions. Three arbitrarily selected optimum designs of the regenerative blower show significant increases in efficiency and reductions in sound pressure level compared to a reference design.