• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 하계학술발표대회
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• pp.199-199
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• 2005

• 한국태양에너지학회 논문집
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• 제34권2호
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• pp.53-59
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• 2014

Ice Rink is energy intensive building type. Concern of energy saving from buildings is one of very important issues nowadays. New and renewable energy sources for buildings are especially important when we concern about energy supply for buildings. Among new and renewable energy sources, use of seawater for heating and cooling is an emerging issue for energy conscious building design. The options of energy use from sea water heat sources are using deep sea water for direct cooling with heat exchange facilities, and using surface layer water with heat pump systems. In this study, energy consumptions for an Ice Rink building are analyzed according to the heat sources of air-conditioning systems; existing system and sea water heat source system, in a coastal city, Kangnung. The location of the city Kangnung is good for using both deep sea water which is constant temperature throughout the year less than $2^{\circ}C$, and surface layer water which should be accompanied with heat pump systems. The result shows that using sea water from 200m and 30m under sea lever can save annual energy consumption about 33% of original system and about 10% of that using seawater from 0m depth. Annual energy consumption is similar between the systems with seawater from 200m and 30m. Although the amount of energy saving in summer of the system with 200m depth is higher than that with 30m depth, the requirement of energy in winter of the system with 200m depth is bigger than that with 30m depth.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.299-303
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• 2008

The treated sewage temperature is about $5^{\circ}C$ lower in summer and $5{\sim}10^{\circ}C$ higher in winter than ambient air. It can be used heat pump heat source and is good heat source on high performance of heat pump. In this study, to develop 100RT 2-stage compression heat pump use treated sewage water heat source and system applies to sewage disposal plant. Although heat pump is better performance, the large temperature difference between load and source makes the performance degradation of a heat pump. To solve this problem screw 2-stage compression is considered. The experiment was focused on the system operating performance variations over supply water and treated sewage water a temperature in the field. The results show that system of heating performance is higher then general heat pump and is enough to supply a hot water of $70^{\circ}C$.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1995년도 춘계학술발표회 초록집
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• pp.78-81
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• 1995

In the present study, the spray column type of direct contact heat exchangers are studied experimentally to analyze heat transfer characteristics for solar energy utilization. These experiments are carried out in the line of solar heating system, major results are as follows ; 1) the flow and aspect of working fluid drop for maxium heat transfer 2) efficiency and volumetric heat transfer coefficient of D. C. H. X. with a heavier working fluid are higher than those of D. C. H. X. with a lighter working fluid

• 한국지열·수열에너지학회논문집
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• 제9권4호
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• pp.1-7
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• 2013

This study is to compare energy consumption of air-source, ground-source and dual-source heat pump systems during intermediate season using dynamic simulation. Ground-source heat pump has higher COP than that of air-source but requires additional power consumption of auxiliary equipment such as circulation pump. During intermediate season when the outdoor air temperature is favorable, total COP of air-source heat pump may be greater than that of ground-source when circulation pump power consumption is included. Dual-source heat pump which selects the more favorable heat source is compared with air-source only and ground-source only heat pumps for total power consumption. Results show that power consumption of dual-source heat pump is lower than that of ground-source only by 0.73%.

• Nuclear Engineering and Technology
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• 제40권2호
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• pp.155-162
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• 2008

Heat transfer experiments in an annulus passage were performed using SPHINX(Supercritical Pressure Heat Transfer Investigation for NeXt Generation), which was constructed at KAERI(Korea Atomic Energy Research Institute), to investigate the heat transfer behaviors of supercritical $CO_{2}$. $CO_{2}$ was selected as the working fluid to utilize its low critical pressure and temperature when compared with water. The mass flux was in the range of 400 to 1200 $kg/m^{2}s$ and the heat flux was chosen at rates up to 150 $kW/m^{2}$. The selected pressures were 7.75 and 8.12 MPa. At lower mass fluxes, heat transfer deterioration occurs if the heat flux increases beyond a certain value. Comparison with the tube test results showed that the degree of heat transfer deterioration in the heat flux was smaller than that in the tube. In addition, the Nusselt number correlation for a normal heat transfer mode is presented.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.395-401
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• 2008

Since metallic foam will increase the performance of heat exchanger, it have caused many researcher's attention recently. Our research base on the model that metallic foams applied to heat exchanger. In this case, there is three kind of heat transfer mechanisms, heat conduction in fibers, heat transfer by conduction in fluid phase, and internal heat change between solid and fluid phases. In this paper we study both the hydraulic and thermal aspect performance. Pressure drop along air flow direction will be presented. As thermal aspect, we first discuss the acceptance of applying thermal equilibrium among the two phases. then to calculate the dimensionless temperature profile, the heat transfer coefficient and Nu number in 14 metallic foams(7 Aluminium foams, 7 FeCrAlY foams). All these discussion is based on the same velocity u=2 m/s.

• 설비공학논문집
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• 제23권8호
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• pp.556-561
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• 2011

In this study, the theoretical maximum power of a heat engine was investigated by sequential Carnot cycle model, for a low-grade heat source of about $100^{\circ}C$. In contrast to conventional approaches, the pattern search algorithm was employed to optimize the two design variables to maximize power. Variations of the maximum power and the optimum values of design variables were investigated for a wide range of UA(overall heat transfer conductance) change. The results show that maximizing heat source utilization does not always maximize power.

• Advances in Energy Research
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• 제4권1호
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• pp.87-106
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• 2016

In this research, optimum design of the combined solar collector, geothermal heat pump and thermal seasonal storage system for heating and cooling a sample greenhouse is studied. In order to optimize the system from technical point of view some new control strategies and functions resulting from important TRNSYS output diagrams are presented. Temperatures of ground, rock bed storage, outlet ground heat exchanger fluid and entering fluid to the evaporator specify our strategies. Optimal heat storage is done with maximum efficiency and minimum loss. Mean seasonal heating and cooling COPs of 4.92 and 7.14 are achieved in series mode as there is no need to start the heat pump sometimes. Furthermore, optimal parallel operation of the storage and the heat pump is studied by applying the same control strategies. Although the aforementioned system has higher mean seasonal heating and cooling COPs (4.96 and 7.18 respectively) and lower initial cost, it requires higher amounts of auxiliary energy either. Soil temperature around ground heat exchanger will also increase up to $1.5^{\circ}C$ after 2 years of operation as a result of seasonal storage. At the end, the optimum combined system is chosen by trade-off between technical and economic issues.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.143.2-143.2
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• 2011

Energy foundations and other thermo-active ground structure, energy wells, energy slab, and pavement heating and cooling represent an innovative technology that contributes to environmental protection and provides substantial long-term cost savings and minimized maintenance. This paper focuses on earth-contact concrete elements that are already required for structural reasons, but which simultaneously work as heat exchangers. Pipes, energy slabs, filled with a heat carrier fluid are installed under conventional structural elements, forming the primary circuit of a geothermal energy system. The natural ground temperature is used as a heat source in winter and heat sink in summer season. The system represented very high heating and cooling performance due to the stability of EWT from energy slab. Maximum heat pump unit COP and system COP were 4.9 and 4.3.