• Transactions of Materials Processing
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• v.27 no.1
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• pp.37-47
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• 2018

In this paper, a double spot welding process, utilizing electric resistance heating dies, is suggested for the spot welding of dissimilar metal plates for drawing and concurrent spot welding. This double welding process has two heating methods for the fusion welding at the interfacial zone between steel and aluminum plates, such as heating method by thermal conduction of electric resistance by welding current induced to heating dies, and heating method by electric resistance between contacted surfaces of two plates by welding current induced to copper electrode. This double welding process has welding variables such as each current induced in heating dies and in copper electrode, outer diameters of heating dies, and edge shape of copper electrode. Experiments for current conditions in welding process should be demanded in order to get successful welding strength. It was known that the welding strength could be reached to the value demanded on industry fields under such welding conditions as heating dies of outer ring dia.12mm contacted on steel plate, as heating dies of outer ring dia. 14mm contacted on aluminum plate, and as copper electrode of dia. 6.0mm, and as 3 times continuous heating method by $1^{st}$ current of 11 kA(9cycle), $2^{nd}$ current 11 kA(60cycle), $3^{rd}$ current 7 kA(60cycle) applied in steel heating dies and copper electrodes, flat edge of copper electrode, for double spot welding process of dissimilar metal plates of steel and aluminum of 1.0 mm thickness.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.668-672
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• 2009

This is to report the result of Development of Single effect/Double lift absorption chiller & heater which is used in the district heating net work. The heating cycle was newly developed to make the secondary hot water from evaporator and the cycle change-over function was added for the heating to the cooling mode and the cooling to the heating mode. Finally, it was assured through the site trial operation that the outlet temperature of primary hot water can be produced lower than $68^{\circ}C$ when the outlet temperature of secondary hot water is $60^{\circ}C$.

• Journal of the Korean Solar Energy Society
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• v.24 no.3
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• pp.39-46
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• 2004

In this paper, thermodynamic design data for heating of double-effect absorption system using LiCl-water for evaporator heating source of sofar energy are investigated for the water-LiCl pair and a comparative study of the water-LiCl pair with the water-LiBr pair is given used for the computer simulation. The computer simulation is based on mass, material and heat balance equations for each part of the system. Coefficients of performance and flow ratios for effects of different operating temperatures are investigated. It is found that the heating COP is higher for the water -LiCl pair than for the water-LiBr pair, and FR is lower for the water-LiCl pair than for the water LiBr pair.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.909-914
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• 2006

The purpose of this study is to analyze the thermal of DFS(double Facade System) and curtain wall in the heating period. The physical difference between curtain wall and double facade on thermal performance has been tested at the newly constructed laboratory, which can turn $360^{\circ}$ to confirm the characteristic of a facade with the various directions. This study divide on 'ventilated, airtight' and 'heated or unheated' conditions from the CASE 1, 2, 3, 4. The results showed thermal performance of double facade system which has been better than curtain wall. The heating energy of DFS reduced $8%{\sim}10%$ of energy consumption. comparable to SFS in experemted results. In view of the researching results so far achieved, the research came to a conclusion, that the curtain wall can save the energy in the heating period than a curtain wall.

• Journal of the Korean Solar Energy Society
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• v.24 no.4
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• pp.77-87
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• 2004

BIPV or double skin applied to the surface of the building, power and thermal load cannot both be increased. In the case of BIPV, because it is applied to the facade, incident solar energy decreases and efficiency drops off. The system in this paper complements these disadvantages and aims to decrease the heating & cooling load by transforming solar energy to electronic and thermal energy. The research in this paper is about the applicability of the clear PV attached double-skin system. And the PV electronic generation and the factors that affect the heating & cooling load such as the daily radiation, sun shading ratio, heating & cooling load, daylight luminance and glare distributions in the building are simulated.

• Journal of the Korean Solar Energy Society
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• v.25 no.3
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• pp.27-35
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• 2005

In this paper, a thermodynamic analysis was performed to provide design data for a double-effect absorption heating system with water-LiBr-LiSCN mixture which utilizes solar energy as evaporator heat source. In addition, a comparative study of the water-LiBr-LiSCN mixture against the water-LiBr pair was conducted by a computer simulation. The computer simulation is based on mass, material and heat balance equations for each part of the system. Coefficients of performance and flow ratios for effects of different operating temperatures are investigated. It is found that the heating COP is higher for the water-LiBr-LiSCN mixture than for the water-LiBr pair, and FR is lower for the former.

• Resources Recycling
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• v.9 no.3
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• pp.13-21
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• 2000

This study describes to analyze the heat transfer characteristics of waste solvent recovery system using a double pipe heat exchanger heating solvent by the hot oil. The solvent recovery system consists of the feeding pump, the double pipe heat exchanger, the vacuum spray chamber, and the condenser. A double pipe heat exchanger consists of the first section to conduct the heating of solvent to the thermal saturated point and the second section to evaporate the saturated solvent. The heat transfer area for vaporization of water, benzene and alkylbenzene was predicted by the heat balance modelling and experimentally measured from the temperature distribution as a function of solvent flow rate and heating temperature. The required heat transfer area for vaporization was increased with increasing solvent flow rates and with decreasing heating temperatures due to decreased quantity of transferred heat per the unit area. Theoretical modelling of the heat transfer area for solvents vaporization in the pipe showed good agreement with experimental results. Results showed to be suitable for the waste solvent recovery using a double pipe heat exchanger.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.183-189
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• 2012

Most of the domestic residential buildings have used the traditional radiant heating system, circulating hot water through the cross-linked polyethylene(PE-X) pipe buried in the floor panel of the heating space. New type of the heating panel was recently developed using heat pipes with double wicks. Some experiments were carried out in this study to verify the thermal characteristics of this heating system at the unit heating space which surrounded by outer space whose temperature of air be maintained scheduled value with time. Through the various experiments with several parameters, such as flow rate, inlet and outlet temperatures of hot water and the heating duration and so on, we found that the floor heating system with heat pipes was able to reduce the pumping power for hot water circulation by 4~31% compared with the conventional panel heating system using PE-X pipe. These results could be used for optimal design and efficient operation of the heating system as well as improvement of thermal comfort.

• Solar Energy
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• v.9 no.3
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• pp.73-80
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• 1989

This paper presents as assessment based on steady-state thermodynamic analysis and computer modeling of a double effect generation absorption heating cycle for solar air-conditioning to find operating temperature ranges. The influences of component temperatures on the heating coefficients of performance and mass flow ratio have been investigated to obtain optimum operating conditions for the proposed air conditioning system. And the single and double effect absorption cycles are compared with each other over the same range of temperatures.

• Journal of the Korean Solar Energy Society
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• v.27 no.3
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• pp.87-94
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• 2007

In this paper, with water-LiCl-$CaCl_2-Zn(NO_3)_2$ mixture which utilizes solar energy at the evaporator heat source, a thermodynamic analysis was performed to provide design data for a double-effect absorption heating system. A comparative study of the water-LiCl-$CaCl_2-Zn(NO_3)_2$ mixture against the water-LiBr pair was conducted by a computer simulation. The computer simulation is based on mass, material and heat balance equations for each part of the system. Coefficients of performance and flow ratios for effects of different operating temperatures are investigated. It is found that the heating COP is higher for the water-LiCl-$CaCl_2-Zn(NO_3)_2$ mixture than for the water-LiBr pair, and FR is lower for the former.