• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.16 no.2
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• pp.7-12
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• 2020

The battery of an electric vehicle is a key part of the energy supply to operate the vehicles. There are many factors affecting battery life such as charging method, discharge rate, and ambient temperature those are requires systematic monitoring and management. To solve the issues like environmental problems and fuel consumption reduction the battery needs more performance improvement. In this study, it was analyzed the thermal characteristics and securing battery stability for electric vehicle battery cooling system. The simulation test was operated using GT-suite software with several conditions like cooling capacity 1, 2 and 4 kW, cooling flow rate 5, 10, 20 and 30 LPM, and battery initial temperatures 40, 35, and 30℃ at the temperature of ambient 25℃. The results shown that the case of cooling flow rate at 20 LPM was most efficient among all above conditions.

• Journal of the Semiconductor & Display Technology
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• v.11 no.4
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• pp.37-42
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• 2012

Nanoimprint lithography (NIL) has attracted broad interest as a low cost method to define nanometer scale patterns in recent years. A major disadvantage of thermal NIL is the thermal cycle, that is, heating over glass transition temperature and then cooling below it, which requires a significant amount of processing time and limits the throughput. One of the methods to overcome this disadvantage is to improve the cooling performance in NIL process. In this paper, the performance of the cooling system of thermal NIL is numerically investigated by SolidWorks Flow Simulation program. The calculated temperatures of nanoimprint device were verified by the measurements. By using the analysis model, the effects of the change of flow velocity and cooler location on the cooling performance are investigated. For the 6 cases (0.1 m/s, 0.5 m/s, 1 m/s, 3 m/s, 5 m/s, 10 m/s) of flow velocity and for the 6 cases of distances (50 mm, 40 mm, 30 mm, 20 mm, 10 mm, 1 mm) of cooler location, the heat conjugated flow analyses are performed and discussed.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.4
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• pp.236-244
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• 2021

Fuel cell systems for medium duty truck require high power demands under driving. Since high power demands results in significant heat generation, thermal management is crucial for the performance and durability of medium duty truck. Therefore, various configurations of dual stacks with cooling systems are investigated to understand appropriate thermal management conditions. The simulation model consists of a dynamic fuel cell stack model, a cooling system model equipped with a controller, and the mounted controller applies a feedback controller to control the operating temperature. Also, In order to minimize parasitic power, the comparison of the cooling systems involved in the arrangement was divided into three case. As a result, this study compares the reaction of fuel cells to the placement of the cooling system under a variety of load conditions to find the best placement method.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.62-67
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• 1998

An experimental study has been carried out to investigate casting process parameters which influence on the microstructures of cast preforms in casting/forging process of aluminum alloy. In the casting process, pouring temperature, pouring time, mold temperature, mold material, and, cooling method are selected as process parameters. With the cast preform, a forging test has been performed to compare mechanical properties of final products between casting/forging process and forging process. From the experimental results, low mold temperature and water cooling method are favorable for obtaining minute microstructures of cast preforms. Casting defects included in cast preforms. such as pores and shrinkage cavity, are eliminated by the forging process. And comparing cast/forged products with conventionally forged products, the former are almost as same as the latter in mechanical characteristics.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.103-108
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• 2003

In this paper, the current lead for superconducting device is studied by numerical method. The current lead is cooled by surrounded $N_{2}$ gas by natural convection. The heat conduction equation for current lead and boundary layer equation for $N_{2}$ gas must be solved simultaneously. The boundary layer equation for $N_{2}$ gas is highly nonlinear for varied temperature of current lead. So the linearization method is adopted for simplicity. Numerical results using natural convection cooling are compared with the conventional cooling methods such as conduction cooling and vapor cooling methods. The main difference of natural convection cooing is the non-zero temperature gradient at the top of current lead for the minimum heat dissipation into superconducting devices. For the optimized conduction-cooling and vapor-cooling current leads, the temperature gradient at the top of current lead is zero. Also, the heat flow at the cold end is much smaller than conduction cooling case.

• Journal of Ocean Engineering and Technology
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• v.2 no.1
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• pp.125-134
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• 1988

The feasibility for improving the cooling rates and mechanical properties of wet welding process is experimentally investigated by using new developed underwater wet electrodes and H.T. steel plates. Main results of this experimental study can be summarized as follows; 1) By shielding around weld arc surrounding, the cooling rates resulting from wet welds with developed electrodes on TMCP steel plates can be lower than of non-shielded wet welds. 2)A high quality of mechanical properties of wet welds on TMCP steel plates can be obtained with shielded weld arc surrounding.

• 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.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.390-395
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• 2001

Cooling characteristics using convection and conduction heat transfer in a parallel channel with extruding heat sources are studied numerically. A two-dimensional model has been developed for numerical prediction of transient, compressible, viscous, laminar flow, and conjugate heat transfer between parallel plates with uniform block heat sources. The finite volume method is used to solve this problem. The considered assembly consists of two channels formed by two covers and one PCB which has three uniform heat source blocks. Five different cooling methods are considered to find efficient cooling method in a given geometry and heat source. The velocity and temperature fields, local temperature distribution along surface of blocks, and the maximum temperature in each block are obtained.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.4
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• pp.345-351
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• 2015

Machine tools usually consume more energy in cooling systems than in spindle motors. This is largely because circulation pumps in the cooling systems are continuously powered to measure the temperature of spindle motors. In this paper, energy saving algorithms are proposed, which modify this behavior of the circulation pumps in such a way that the circulation pumps run only when it is likely that the information on the temperature is critical to bang-bang control of compressors in cooling systems. A mathematical model is established that explains heat transfer phenomena near the spindle motors. The power consumptions are measured for individual components in a machine tool, and the parameters that appear in the mathematical model are estimated. Computer simulations are performed with the estimated parameters, and the results are compared with the experimental ones. It turns out that a large amount of energy can be saved by using the proposed method.

• The KSFM Journal of Fluid Machinery
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• v.19 no.5
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• pp.42-49
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• 2016

Aerodynamic analysis of a low-voltage electric motor has been performed with various inlet vent shapes. Effects of inlet vent shape on aerodynamic performance of a motor cooling fan have been investigated numerically using three-dimensional Reynolds-averaged Navier-Stokes equations. The k-${\varepsilon}$ turbulence model was used for the analysis of turbulence. The finite volume method and unstructured tetrahedral grids were used in the numerical analysis. Optimal grid system in the computational domain was selected through a grid-dependency test. From the results of the flow analysis, considerable energy loss by flow separation was observed in the flow passage. It was found that mass flow rate through the cooling fan in the low-voltage motor can be increased by modifying the inlet vent shape. And, some inlet vent shapes were suggested to improve the aerodynamic performance of the motor cooling fan.