• Journal of the Korean Society for Precision Engineering
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• v.19 no.7
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• pp.163-170
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• 2002

This paper presents some measures far the optimization of the thermal behavior of linear motors, which are used as a high speed feed mechanism in machine tools. Thermo-Sandwich-Construction using two cooling circuits and an insulation layer shows an effective cooling system for linear motors. Conducting sheet can be also used to reduce heat flow from linear motor to machine table. Cooling pipe is a simple and effective cooling system for the secondary part of synchronous linear motor. Through the combination of the Thermo-Sandwich-Construction, conducting sheet and cooling pipe the thermally optimized linear motor shows a well improved thermal behavior in comparison with the prototype motor.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.110-117
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• 2022

A chiller cooler absorbs the thermal energy of water to generate cold water and supplies the generated cold water to a cold water pipe buried in the wall of a small mobile modular house to greatly increase the cooling area. An attempt was made to reduce the required cooling time significantly. A small chiller cooler suitable for the cooling load of a small mobile modular house with an area less than 3.3 m² was employed. When cooling is done during summer using a chiller cooler installed outdoors, heat absorption energy loss occurs in the cold water pipe owing to the high temperature. To address this, a study was conducted to reduce the endothermic energy loss significantly. As the mass flow rate of the cold water flowing inside the cold water pipe increased, the temperature decrease gradient of the cold water increased. From the start of the cooling operation, the air temperature of the small mobile modular house decreased linearly in proportion to the operation time. Furthermore, the temperature of the air inside the small mobile modular house decreased in proportion to the increase in the flow of water inside the cold water pipe.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.8
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• pp.741-747
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• 2004

The purpose of this study was to develop a cooler/heater using a thermoelectric module combined with a parallel flow type oscillating heat pipe with R-142b as a work ing fluid. The experiment was performed for 16 thermoelectric modules (6 A/15 V, size: 40${\times}$40${\times}$4 mm), varying design parameters of the heat pipe (inclination angle, working fluid charging ratio, etc) . Experimental results indicate that the optimum charging ratio and the inclination angle of the parallel flow type oscillating heat pipe were 30% by volume and 30%, respectively. The maximum cooler/heater capacity were 479W (COP : 0.47) and 630W (COP : 0.9), respectively.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.4
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• pp.217-224
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• 2005

The purpose of this study was to develop a cooler/heater using a thermoelectric module combined with a parallel flow type pulsating heat pipe with R-142b as a working fluid. The experiment was performed for 16 thermoelectric modules (6A/15V, size: $40\times40\times4mm$), varying design parameters of the heat pipe (inclination angle, working fluid charging ratio, etc.). Experimental results indicate that the optimum charging ratio and the inclination angle of the parallel flow type pulsating heat pipe were $30\%$ by volume and $30^{\circ}$, respectively. The maximum cooler/heater capacity were 479 W (COP: 0.47) and 630 W (COP: 0.9), respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.867-868
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• 2010

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.30-36
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• 2010

The heat flowrate and pressure drop of $CO_2$ in a multi-tube-in-tube helical coil type gas cooler were investigated experimentally. The mass flowrate of $CO_2$ and coolant were varied from 0.06 to 0.075 [kg/s], respectively and the cooling pressure of gas cooler were from 8 to 10 [MPa]. The heat flowrate of $CO_2$ in the test section is increased with the increase in mass flowrate of coolant, the cooling pressure and mass flowrate of $CO_2$. The pressure drop of $CO_2$ is decreased with the decrease in mass flowrate of coolant and $CO_2$, but decreased with increase in cooling pressure of $CO_2$. The heat flowrate of $CO_2$ in the multi-tube-in-tube helical coil type gas cooler is greatly higher than that of $CO_2$ in the double pipe type gas cooler, while the pressure drop of $CO_2$ in the multi-tube-in-tube helical coil type gas cooler is greatly lower than that of $CO_2$ in the double pipe type gas cooler. Therefore, in case of the application of $CO_2$ at the multi-tube-in-tube helical coil type gas cooler, it is expected to carry out the high-efficiency, high-performance and compactness of gas cooler.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.3
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• pp.213-220
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• 2007

Appropriate numerical models for the simulation of off-gas flow in hot area of the vitrification plant have been developed in this study. The models have been applied to analyze the effect of design parameters of real plant and numerical analyses have been performed for CCM(Cold Crucible Melter), pipe cooler and HTF(High Temperature Filter). At first, the effect of excess oxygen and the ratio of oxygen distribution on combustion characteristics in the CCM has been studied. Next, solidification behavior of radio nuclide in the pipe cooler has been numerically modeled and scrutinized. Finally, flow pattern in accordance with the location of off-gas entrance of the HTF has been compared.

• Journal of the Korean Institute of Educational Facilities
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• v.18 no.3
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• pp.35-41
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• 2011

Performance of a small-capacity solar absorption cooling system was investigated experimentally. Ten sets of evacuative-tube solar-heat collectors and a 5 kW single-stage absorption cooler were combined to produce a hybrid cooling system. The performance of the cooling system was measured using a tim-coil unit installed in a small plastic storage. It was found from the test on a sunny day of May that when the temperature of the hot water supplied from the solar collectors to the generator of the absorption cooler reached $60^{\circ}C$, the absorption cooler started cooling and the cold water temperature measured from the fan-coil unit reached $18^{\circ}C$. The COP, which is defined as the ratio of the cooling power to the total electrical power input was higher than 1.0.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.216-221
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• 2005

The heat transfer coefficient and pressure drop during gas cooling process of carbon dioxide in a helically coiled tube were investigated experimentally. The experiments were conducted without oil in the refrigerant loop. The main components of the refrigerant loop are a receiver, a variable speed pump, a mass flowmeter, a pre-heater, a gas cooler(test section) and an isothermal tank. The test section is a double pipe type heat exchanger with refrigerant flowing in the inner tube and water flowing in the annulus. It was made of a copper tube with the inner diameter of 4.85 [mm], the outer diameter of 6.35 [mm] and length of 10000 [mm]. The refrigerant mass fluxes were 200${\sim}$600 [kg/$m^2$s] and the average pressure varied from 7.5 [MPa] to 10.0 [MPa]. The main results were summarized as follows: The heat transfer coefficient of supercritical $CO_2$ increases, as the cooling pressure of gas cooler decreases. And the heat transfer coefficient increases with the increase of the refrigerant mass flux. The pressure drop decreases in increase of the gas cooler pressure and increases with increase the refrigerant mass flux.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11a
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• pp.69-78
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• 2005

Appropriate numerical models for the simulation of off-gas flow in hot area of the vitrification plant have been developed in this study. The models have been applied to analyze the effect of design parameters of real plant and numerical analyses have been performed for CCM(Cold Crucible Melter), pipe cooler and HTF(High Temperature Filter) At first, the effect of excess oxygen and the ratio of oxygen distribution on combustion characteristics in the CCM has been studied. Next, solidification behavior of radio nuclide In the pipe tooler has been numerically modeled and scrutinized. Finally, flow pattern In accordance with the location of off-gas entrance of the HTF has been compared.