• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.59-64
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• 2014

Integrated Starter Generator (ISG) system improves the fuel economy of hybrid electric vehicles by using idle stop and go function, and regenerative braking system. To obtain the high performance and durability of ISG motor under continuously high load condition, the motor needs to properly design the cooling system (cooling fan and cooling structure). In this study, we suggested the enhanced design by modifying the thermal design of the ISG motor and then analyzed the improvement of the cooling performance under high-speed condition and generating mode by CFD simulation. The temperatures at the coil and the magnet of the enhanced model were decreased by about $4^{\circ}C$ and $6^{\circ}C$, respectively, compared to those of the conventional model. Therefore, we verified the cooling performance enhancement of the novel thermal design in the case of core loss increment due to the higher speed condition.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.6
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• pp.58-63
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• 2016

This paper presents a study of heat dissipation away from the fuel combustion of a marine diesel engine. These engines are operated for long periods under high load conditions: so cooling systems are necessary for radiation and control of the high temperature levels. In the study, each component of the water cooling system was developed to achieve improvements in cooling and safety. Heat transfer considerations and arrangement design for the components were important and an intercooler and exhaust manifold incorporated. An optimization of the cooling water's flow path was achieved subject to the need for convenient maintenance. The 750Ps marine diesel engine was used for performance testing of the cooling system. The test results showed adequate cooling performance improvement.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.63-72
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• 2011

In recent years, hot-stamped components are more increasingly used in the automotive industry in order to reduce weight and to improve the strength of vehicles. In hot stamping process, blank is hot formed and press hardened in a tool. However, in hot stamping without cooling channel, temperature of the tool increases gradually in mass production thus cannot meet the critical cooling rate to obtain high strength over 1500MPa. Warpage occurs in the hot stamped component due to non-uniform stress state caused by unbalanced cooling. Therefore, tools should be uniformly as well as rapidly cooled down by the coolant which flows through cooling channel. In this paper, optimal design method of cooling channel to obtain uniform and high strength of the component is proposed. Optimized cooling channel is applied to the hot press V-bending process. As a result of measuring strength, hardness and microstructure of the hot formed parts, it is known that the design methodology of cooling channel is effective to the hot stamping process.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.4
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• pp.85-92
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• 2006

A design program has been developed to predict film cooling performance of a liquid rocket engine. A thermal protecting effect of low mixture ratio gas layer has been analysed by CFD. A one-dimensional film cooling model based on the CFD results has been implemented to the previously developed design program of regenerative cooling. Satisfactory agreement has been achieved by comparing the predicted maximum heat flux at the throat of a subscale chamber and the average measured value, and the predicted nozzle average heat flux and the measured value for a full scale chamber with film cooling. It is ascertained that the film cooling is effective to reduce the throat heat flux in rocket engine chamber.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.7-12
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• 2016

This paper deals with a parametric study on cooling channel configurations to enhance the cooling effect. As a cooling effect has been increased, the exhaust gas by the plant from a manufacture is becoming deceased. To solve this problem, the design of a efficient cooling system is needed. In this paper, the cooling channel was analyzed to improve the cooling performance. The heat transfer rates depending on the number of baffle and the heiht of fin were obtained by using numerical simulation method. Three-dimensional Reynolds-averaged Naiver-Stokes equations were used to estimate flow and heat transfer in cooling channel, and the $k-{\varepsilon}$ model for turbulence closure was employed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1487-1492
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• 2010

The objective of this study is to design the conformal cooling channels for the mould of a plastic drawer of a refrigerator by analysis of three-dimensional injection molding. In order to obtain the desired design of the conformal cooling channels, the influence of the diameter and the position of the conformal cooling channels on the moulding characteristics and the product qualities were quantitatively examined. From the results of the examination, an optimal design of the conformal cooling channels, which ensures uniform cooling and minimum potential deformation of the molded drawers, was estimated. By comparing the designed mould and a conventional mould with linear cooling channels from the viewpoints of the product qualities as well as cooling and cycle times, it was shown that the mould with conformal cooling channels can simultaneously improve the productivity of the injection moulding process and the product qualities.

• Tribology and Lubricants
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• v.25 no.6
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• pp.387-398
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• 2009

The operation condition of recently designed pistons for high power and high speed diesel engine become more severe due to the increment of combustion pressure and temperature. So, in order to overcome high temperature, the application of the mono-metal cast aluminum alloy piston featuring an enclosed cast-in open cooling gallery has increased. In this research, it is developed a PCJ (piston cooling jet) rig tester, described the test procedure and validated the performance of sample piston cooling gallery design. Then the test rig will be used for developing the design technology of piston cooling gallery. The test rig is composed with oil reservoir and pumping system, oil jet system, piston fixing and moving system, collecting oil measuring system, and data measuring and recording system. It will be measured collecting efficiencies under conditions of a few piston positions, oil jet pressures and oil viscosities for a piston cooling gallery. Furthermore, the PCJ rig tester will be used for the optimum design of the oil cooling gallery which being applied to increase the cooling efficiency of pistons in diesel engines satisfying the EURO V emission regulation and the more.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.72-80
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• 2013

For the proper cooling of in-wheel motor, the cooling channel should have the characteristics which are low pressure drop and adequate cooling oil supply to motor part. In this study, the flow performance of cooling channel for in-wheel motor was evaluated and the shape of the channel was optimized. First, the pressure drop and flow distribution characteristics of the initial channel model were evaluated using numerical analysis. Also, by the result of analysis and design modification, 4 design parameters of the channel were selected. Second, using the Taguchi optimal method, the cooling channel was optimized. In the method, nine models with different levels of the design parameters were generated and the flow characteristics of each models was estimated. Base on the result, the main effect of the design parameters was founded and optimized model was obtained. For the optimized model, the pressure drop and oil flow rate were about 0.196 bar and 0.207 L/min, respectively. The pressure drop decreased by about 0.3 bar and the oil flow rate to the motor part increased by about 0.2 L/min compared to the initial model.

• Structural Engineering and Mechanics
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• v.46 no.5
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• pp.735-753
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• 2013

The wind load is always the dominant load of cooling tower due to its large size, complex geometry and thin-wall structure. At present, when computing the wind-induced response of the large-scale cooling tower, the wind pressure distribution is obtained based on code regulations, wind tunnel test or computational fluid dynamic (CFD) analysis, and then is imposed on the tower structure. However, such method fails to consider the change of the wind load with the deformation of cooling tower, which may result in error of the wind load. In this paper, the analysis of the large cooling tower based on the iterative method for wind pressure is studied, in which the advantages of CFD and finite element method (FEM) are combined in order to improve the accuracy. The comparative study of the results obtained from the code regulations and iterative method is conducted. The results show that with the increase of the mean wind speed, the difference between the methods becomes bigger. On the other hand, based on the design of experiment (DOE), an approximate model is built for the optimal design of the large-scale cooling tower by a two-level optimization strategy, which makes use of code-based design method and the proposed iterative method. The results of the numerical example demonstrate the feasibility and efficiency of the proposed method.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.361-364
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• 2009

The cooling system optimization for injection molds was studied with a response surface method in the previous research. It took so much time to find an optimum solution for a large product due to an extensive amount of calculation time for the CAE analysis. In order to use the optimization technique in the actual design process, the calculation time should be much reduced. In this study, we tried to reduce the number of design variables with the concept of the close relationship between the depth and the distance of cooling channels. The optimum ratio of the distance to the depth of cooling channels for a 2-dimensional problem was 2.0 so that the optimum ratio was again sought out for 4 industrial products. The major cooling effect of the injection molds for large products rely on baffle tubes. The optimum ratio of the distance to the depth for baffle tubes was 2.0 for the large products. The result enables us to reduce the number of the design variables by half in the cooling system optimization problem.