• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.915-920
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• 2006

Recently available heat pump system by using air heat-source is not efficient. Because the mean temperature of korean winter season is low, economy of air heat-source heat pump descend, and COP is below 3.0. This paper was practiced the simulation on evaluation criteria for heat pump heating and cooling systems to resident building. As a result, heating and cooling composition heat pump system apply to the building needed to be provided heat source for 24 hours.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.6
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• pp.73-77
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• 2019

In this paper, the heat pump system was designed using heat absorption of the refrigerant or condensation heat. The cooperation system has been developed to pass a heat source of low temperature to a high temperature or to pass the heat source of high temperature to a low temperature. Heat pump for using the valve as a function of switching a condenser and an evaporator in a refrigerating cycle. As a result, heat pump system was developed by air source method. Therefore cooperating system for energy saving to solve at the same time as the cooling and heating by system of one was equipped.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1530-1535
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• 2003

The utilization of unused energy is important because it can afford to offer a chance to increase energy efficiency of a heat pump system. One of the promising unused energy sources is river water. It can be used as a heat source in both heating and cooling effectively with its superior features as a secondary working fluids. In this study, the performance of a 5HP heat pump system using river water as a heat source is investigated by both experiment and simulation. According to system simulation results, performance improvement of condenser seems more effective than that of evaporator for better $COP_H$. The serial connection is also preferred among several methods to improve plate type heat exchanger performance. The experimental results show that the hot water of $50{\sim}60^{\circ}C$ can be acquired from water heat source of $5{\sim}9^{\circ}C$ with $COP_H$ of $2.7{\sim}3.5$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.11
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• pp.600-605
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• 2013

Ground source heat pump systems (GSHP) can achieve higher performance of the system, by supplying more efficient heat source to the heat pump, than the conventional air-source heat pump system. But building clients and designers have hesitated to use GSHP systems, due to expensive initial cost, and uncertain economic feasibility. In order to reduce the initial cost, many researches have focused on the energy-pile system, using the structure of the building as a heat exchanger. Even though several experimental studies for the energy-pile system have been conducted, there was not enough data of quantitative evaluation with economic analysis and comprehensive analysis for the energy-pile. In this study, a prediction method has been developed for the energy pile system with barrette pile, using the ground heat transfer model and ground heat exchanger model. Moreover, a feasibility study for the energy pile system with barrette pile was conducted, by performance analysis and LCC assessment. As a result, it was found that the heat exchange rate of a barrette pile was 2.55 kW, and the payback period using LCC analysis was 8.8 years.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.7
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• pp.585-590
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• 2012

The objective of this study is to investigate the performance of a two-stage compression heat pump system for district heating. The experimental setup of heat pump consists of compressor, condenser, evaporator, expansion device, intercooler, flash tank, oil separator and accumulator. The experimental evaluations on the two-stage compression cycle were carried out under various operating conditions which were heat source temperature, the degree of compressor inlet superheat, and intermediate pressure. The temperature ranges of unutilized energy as the heat source were used in the test conditions. As the heat source temperature increased from $10^{\circ}C$ to $30^{\circ}C$, the COP and heating capacity of the heat pump system increased by 22.6% and 45.8%, respectively. The performance of the two-stage heat pump system increased by 5.2% with the variation of the intermediate pressure in the same heat source temperature conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.3
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• pp.221-230
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• 2002

In this study, in-situ performance test of an air source heat pump which has a arted capacity of 10 RT is carried out. Since test conditions, such as indoor and outdoor air conditions cannot be controlled to satisfy the standard test conditions, experiments are done with the inlet air conditions as they exist. To estimate the performance for other conditions, he heat pump is modeled with a small number of selected parameters. The values of the parameters are determined from the few measurements measured on-site during normal operation. A simulation program is developed to calculate cooling capacity and power consumption t any other operating conditions. The simulation results are in good agreement with the experiment. This study provides a method of an on-site performance diagnosis of an air source heat pump.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1623-1629
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• 2003

In this paper, the arc beam is considered as a moving disc heat source with a pseudo-Gaussian distribution of heat intensity. The solution for temperature distribution on welds is derived by using the image heat source method and the superposition method. It is general solution in that it can determine the temperature-rise distribution in and around the arc beam heat source, as well as the width and depth of the melt pool (MP) and the heat-affected zone (HAZ) in welding short lengths, where quasi-stationary conditions may not have been established. As a comparative study, the results of this analytical approach has been compared with that of the finite-element modeling. As a result, The theoretical analysis presented here has shown good consistency and is more time/cost-effective method compared with FEM.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.16 no.4
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• pp.24-30
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• 2020

Ground source heat pump (GSHP) systems are actively introduced as cooling and heating conditioning systems of buildings due to annual stable performance and easily maintenance. However, ground temperature imbalance is occurred when the GSHP is used for a long period. Therefore, in this study, we proposed the operation method of the system that considered the recovery time of heat source temperature. The entering water temperature (EWT) and heat exchange rate (HER) were comparatively analyzed according to the continuous and intermittent operation. Furthermore, the underground thermal environment was evaluated by numerical analysis model. As the result, the intermittent operation was a maximum of 12.3% higher HER during the heating period than the continuous operation. In addition, the overall ground heat source temperature at the intermittent operation was higher than it at the continuous operation.

• Journal of Power System Engineering
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• v.21 no.2
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• pp.64-69
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• 2017

The purpose of this study is to investigate the performance characteristics of seawater cooling system for a fishing vessel. The circulation amount of refrigerant, condensation capacity, evaporation capacity, compression work and coefficient of performance(COP) were analyzed as the heat source temperature changed. The experimental setup consisted of an open-type compressor, a shell&tube type condenser, an evaporator and an expansion valve. The heat source was controlled by a constant temperature chamber. The main results of this study are summarized as follows. The condensation capacity increased with increasing heat source temperature, and it was confirmed that the effect of circulating amount of refrigerant was dominant. The amount of heat for vaporization was almost constant even though the temperature of the heat source increased. On the other hand, the compression power was increased. This is because the compression ratio increases as the condensation pressure, the enthalpy difference between inlet and outlet, the amount of circulating refrigerant increases. The performance coefficient of this system showed a tendency decreasing with increasing heat source temperature. Therefore, the basic data of the seawater cooling system for the maintenance of the catch line of the shore fishing boats was acquired through this study, and it is considered that it will be sufficient for the actual design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.8
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• pp.664-671
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• 2006

We propose the correlation to predict the spreading thermal resistance on a plate with symmetrical four heat sources. The correlation transforms four heat sources to a single equivalent heat source and then the spreading thermal resistance can be obtained with the existing equation for a single heat source. When the four heat sources are mounted on a square base plate, the correlation is expressed as a function of the heat source size, the length of base plate, the plate thermal conductivity and the distance between heat sources. Compared to the results of three-dimensional numerical analysis, the spreading thermal resistance by the proposed correlation is in good agreement within 10 percent accuracy.