• 설비공학논문집
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• 제16권12호
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• pp.1204-1211
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• 2004

It is difficult to apply a conventional selection guide for diffusers when the diffuser is installed in a perimeter zone, because the air diffusion performance index (ADPI) vs. throw/length (T/L) ratio curve listed in conventional guide does not consider the perimetric heating load through the walls. The objective of this study is to evaluate the effect of the perimetric heating load on the ADPI and propose a selection guide for a proper line diffuser when perimetric heating load exists. The velocity and temperature distributions and the ADPI values are obtained numerically with various heat load ratios and air flow rates. The velocity and temperature distributions and the ADPI values are analyzed by CFD in case of various heat load ratios and air flow rates. Also, ADPI was calculated by those results. The ADPI values by numerical results are compared with an existing experimental data to verify the method for the evaluation of ADPI proposed in a present study. In case of a line diffuser installed at the high side wall, the ADPI decreases according to the increases of the flow rate on every heat load ratio of the present study except 0.75. The ADPI vs. T/L ratio curves have been proposed for the heat load ratios of 0.25, 0.5, 0.75 to guarantee the comport thermal environment when diffusers are installed in perimeter zone.

• 설비공학논문집
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• 제16권1호
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• pp.34-41
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• 2004

The chemical heat pump based on the Dehydration/Hydration process with a MgO/$H_2O$ system has been researched. The reactor bed could be expected to store the heat around 200∼37$0^{\circ}C$ by the dehydration reaction and to release the heat around 100∼16$0^{\circ}C$ by the hydration reaction under the heat amplification mode operation. The heat output rate of the heat pump system was evaluated using the experimentally determined parameters. The results show that 6∼50 W/kg of heat output and 0.5∼0.8 of heat recovery ratio are attainable. The heat pump will be applicable for a load leveling in a co-generation system by chemical storage of surplus heat at low heat demand and by supplying heat in the peak load period.

• 전기학회논문지
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• 제63권11호
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• pp.1575-1581
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• 2014

In this paper, eddy current loss, iron loss and heat transfer of PMSG with 2,000kW capacities were analyzed for wind turbine. The PMSG with 3 split magnet was analyzed using ansoft maxwell commercial program and, generator was tested by Back to Back converter with no load condition at laboratory. Rotor surface temperature was measured by Pt100 sensors for investigating heat transfer from rotor to atmosphere. The simulation results shows 27.4kW eddy current loss in no load condition and 50.2kW eddy current loss in rated load condition with 3 split magnet, and also shows 4.3kW iron loss in no load condition and 7.3kW iron loss rated load condition. The heat transfer coefficient of convection between rotor surface and atmosphere was investigated by $9.6W/m^2{\cdot}K$. Therefore the heat transfer from rotor to atmosphere was about 17kW(54%) and from rotor to air-gap was about 14.6kW(46%) in no load condition. It is identified that the cooling system for stator have to include the 46% of iron loss, and heat dissipation structure of rotor surface have to be suggested and designed for efficiency improvement of generator.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.9-16
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• 2004

Close-coupled catalyst (CCC) can reduce the engine cold-start emissions by utilizing the energy in the exhaust gas. However, in case the engine is operated at high engine speed and load condition, the catalytic converter may be damaged and eventually deactivated by thermal aging. Excess fuel is sometimes supplied intentionally to lower the exhaust gas temperature avoiding the thermal aging. This sacrifices the fuel economy and exhaust emissions. This paper describes the results of an exhaust heat exchanger to lower the exhaust gas temperature mainly under high load conditions. The heat exchanger was installed between the exhaust manifold and the inlet of close-coupled catalytic converter. The exhaust heat exchanger successfully decreased the exhaust gas temperature, which eliminated the requirement of fuel enrichment under high load conditions. However, the cooling of the exhaust gas through the heat exchanger may cause the deterioration of exhaust emissions at cold start due to the increment of catalyst light-off time.

• Journal of Advanced Marine Engineering and Technology
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• 제30권2호
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• pp.204-210
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• 2006

This study presents heat pump system characteristics using hydrocarbon refrigerants as alternative refrigerant for R-22 with respect to the variation of indoor load. Pure R-22 and R-290. R-600a, R-1270 were considered as working fluids The experimental apparatus was constructed to investigate the performance of heat pump using the air as a heat source. The performance were calculated based on compression shaft work. refrigeration capacity. pressure ratio, discharge temperature and COP. The experimental results show that the COP and refrigeration capacity of hydrocarbon refrigerants were higher than that of R-22. Through the above. hydrocarbon refrigerants are good alternatives in the heat pump system for R-22.

• 대한건축학회논문집:구조계
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• 제35권10호
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• pp.235-243
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• 2019

In South Korea, millions of poultry have died due to repeated heat waves every year. The purpose of this study is to analyze the characteristics of heating and cooling loads of chicken houses in Korea and to present an effective insulation and ventilation measures to minimize the damage of poultry due to summer heat wave and to save energy in chicken houses in winter. The heating and cooling loads of standard chicken house were calculated. As a result of the calculation of maximum heating load based on the minimum ventilation rate in winter, the outdoor air temperature requiring heating was $6{\sim}7^{\circ}C$ to keep the indoor air temperature of chicken houses as $24^{\circ}C$. The peak cooling load of chicken houses was mostly taken by the heat generated by chickens and the heat gain due to ventilation. The heat gain through building envelopes was as small as neglectable. Most of chicken houses is usually cooled by gigantic forced ventilation in summer in Korea. When the chicken houses are cooled by electric cooling machine such as cooler or air conditioner, it is more effective to keep minimum ventilation rate to reduce the maximum cooling load. To lower the temperature of supplying water to cooling pad, it is recommended to use the underground water below 10 meters from the ground if there is abundant underground water.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.125-126
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• 2007

This paper presents a CHP Heat Exchange Mechanism considering Economic Load Dispatch with Dynamic Programming. It calculates CHP heat generation cost and Heat load pattern. Also It presents CHP optimal operation through appliance of Heat Exchange Mechanism and investigates CHP optimal operation effects about connected two regions.

• 대한기계학회논문집
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• 제18권8호
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• pp.2167-2176
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• 1994

This paper presents some useful design criteria for the turbine cogeneration system through both the design and off-design analysis. Comparative analysis of the part load performance is carried out for several gas turbines which have different design parameters represented by the turbine inlet temperature and pressure ratio. It is shown that the variation in part load efficiency considerably depends on the design parameter. The off-design operation of the heat recovery steam generator is simulated by introducing adequate assumptions for the heat transfer process. It is turned out that the design parameters of heat recovery steam generator should be determined by considering the favorable operation at the off-design conditions.

• 한국초전도ㆍ저온공학회논문지
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• 제4권2호
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• pp.68-72
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• 2002

This work investigates the transient cooling characteristics of an Infrared (IR) detector cryochamber, which has a critical effect on the cooling load. The current thermal modeling considers the conduction heat transfer through a cold well. the gaseous conduction due to outgassing. and the radiation heat transfer. The transient cooling Performance. i.e. the penetration depth and cooling load, is determined using a finite difference method. It is found that the penetration depth increases as the bore conductivity increases. Gaseous conduction and radiation hardly affect the penetration depth. The transient cooling load increases as the bore conductivity increases. The effects of gaseous conduction and radiation on transient heat transfer are weak at initial stages of cooling. However, their effects become significant as the cooling Process Proceeds.

• 설비공학논문집
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• 제24권3호
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• pp.212-217
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• 2012

The cooling of data centers has emerged as a significant challenge as the density of IT equipment increased. With the rapid increasing of heat load and cooling system, predictions for electronics power trends have been closely watched. A data center power density projection is needed so that IT organizations can develop data centers with adequate cooling for reasonable lifetimes. This paper will discuss the need for something more than processor and equipment power trend projections which have overestimated the required infrastructure for customers. This projection will use data from a survey of actual enterprise data centers and the ASHRAE projections to formulate a data center server heat load trend projection.