• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6053-6059
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• 2013

Heat pumps have attracted considerable attention as a green energy system because they use renewable energy, such as geothermal, solar energy and waste heat, and can have a low electricity consumption rate compared to other conventional electric heating system. Many studies of high efficient heat pump system design was performed previously,but it is not easy to find any an analytical model that consists of components (e.g. compressor, heat exchangers, and expansion valve), not only having an interrelation and interconnection each other but also being flexible to any change in geometry and operating parameters. In this study, a computational model was developed for a heat pump with warm air as a heat source using the one-dimensional modeling software, AMESim. In combination with an independently-developed analytical model for a scroll compressor, the heat pump model can simulate the physical characteristics and actual behavior of the heat pump precisely. In addition, the reliability of the model was improved by verifying the simulation results using experimental data. The simulation data fell into the 10% error range compared with the experimental data. The heat pump model can be used for system optimization studies of product development and applied to other applications in a range of industrial field.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.924-930
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• 2018

The objective of this study was to investigate heating performance characteristics of electric heat pump system in a fuel cell electric vehicle (FCEV). In order to analyze heating performance characteristics of electric heat pump system with plate-type heat exchanger using stack coolant to evaporate the refrigerant, R-134a, each component was installed and tested under various operating conditions, such as air inlet temperature of inner condenser and compressor speed. When the air inlet temperature of inner condenser was varied from $0.0^{\circ}C$ to $-20.0^{\circ}C$, heating capacity was not quite different due to similar temperature gap between inlet and outlet of inner condenser with electric-driven expansion valve (EEV). However, COP increased until certain EEV opening, especially under 45.0%, because of decreasing power consumption. According to the compressor speed variation from 2,000 to 4,000 RPM, heating capacity and COP were found to have opposite trend. In the future works, stack coolant conditions as the heat source for tested heat pump system were analyzed with respect to heating performance, such as heating capacity and COP.

• Journal of the Korean Institute of Educational Facilities
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• v.16 no.1
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• pp.43-50
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• 2009

This research is to analyze LCC of Heat Pump system in university building by reduction of electric power costs for education and incentive system for gas. Produced details item different expense of EHP and GHP equipment construction step and preservation administration step. Analysis result is as following. 1) Executed LCC analysis for target system after lowering whole curriculum reduction of electric power costs for education. Analysis result, energy cost-cutting effect of EHP appears greatly than GHP unlike existent study finding, EHP decided by economical system. 2) Sensitivity analysis executed by incentive 500,000 won per units and geometrical ration of gas expense by 1%. As a result, because lowering effect of electric charges appears greatly, EHP decided by more economical system than GHP. As research result of front is different from existent study finding, EHP by lowering of electric charges for alteration and education of governmental frequent volunteer system was decided by more economical system than GHP.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3827-3834
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• 2012

Recently, instead of hot air type dryers that require a lot of heat, energy-efficient heat pump dryers have been used in various fields such as paper, textile, wood, food, etc. In this paper, the characteristics of heat pump cycle were theoretically evaluated with hot-gas bypass system to further improve the energy efficiency by minimizing the use of electric heaters in early warm-up stage of the dryers for frozen agricultural products. In addition, damper system that leads outside air to flow into the dryer were optimized to obtain extra heat for higher energy efficiency.

• Journal of the Korean Solar Energy Society
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• v.34 no.1
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• pp.58-63
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• 2014

A vertical closed loop ground source heat pump (GSHP) is used to produce heat from the low-grade energy source such as the outside air and ground source. It is known that a heat pump system type has better efficiency comparing to the electric heating system. This study only demonstrates that the vertical closed loop GSHP system is a feasible choice for space cooling of air conditioning. The coefficient of performance (COP) is the ratio of heat output to work supplied to the system in the form of electricity. For the vertical closed loop GSHP system in a cooling mode, the COP is the most commonly used way for judging the efficiency. For the purpose of this experiment, vertical closed loop GSHP system was installed in the laboratory and the experiment was executed. As a result, an average COP of vertical-closed loop GSHP system was 3.62 when the outside average temperature was $33^{\circ}C$.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.2
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• pp.361-368
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• 2019

This paper is a study on integrated air-conditioning system for 1-ton class commercial vehicle based on electric vehicle. In the case of an electric commercial vehicle, since the opening and closing of the door is frequently performed in order to get in and out of the cargo, the heat loss largely occurs. Therefore, the heating and cooling load is required to be larger than the electric vehicle. As a result, the energy consumed by the heating and cooling system is larger than the passenger electric car in order to satisfy the heat comfort required by passengers. In order to overcome these disadvantages, we performed research using an efficient integrated air conditioning system. Finally, the design and analysis of a heat pump system for heating and a electrical compressor for cooling need to be proceed to develop a high-efficiency air conditioning system for improving the commerciality of 1 ton-class electric trucks and expanding the industrial ecosystem in the electric truck sector.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.5
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• pp.467-472
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• 2013

A raw-water source heat pump equipped with a thermal storage tank was dynamically simulated by TRNSYS, and the results were verified by using the data from a heat pump installed in the Seongnam water treatment facility. The average coefficient of performance (COP) of the raw-water source heat pump based on simulation was 4.97 and 3.17 in the cooling and heating season, respectively. When the volume of the thermal storage tank was changed from 5 to $20m^3$, the highest COP was found at a size of $10m^3$. Considering the regional locations of raw-water source heat pumps at Seoul, Incheon, Gangneung, and Gwangju, Seoul showed the lowest electric power consumption in the cooling season and the highest in the heating season. When a comparison of the performance between the present system and that of a water-air heat pump was conducted, the present system showed lower electric power consumption by 25% than that of a water-air heat pump.

• The Journal of Sustainable Design and Educational Environment Research
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• v.6 no.2
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• pp.25-52
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• 2007

This paper is focused on the economical efficiency of the geothermal heat pump system in school. As the importance of problems of environment and energy becomes larger, the development and distribution of energy-saving technology in the whole nation has become influential. This paper is intended, targeting on school buildings scattered all over the country, to evaluate the introduction and possibility of a terrestrial heat system which is in the first stage of introduction in the country, through energy consumption and efficiency in case where a terrestrial heat system is introduced. To do that, the author performed a qualitative analysis of the heat pump system using various terrestrial heat energy and the system introduced to existing school buildings and, through the analysis, made tentative evaluation on the most environment-friendly and energy saving type system. Also, the author performed simulation analysis using a currently typical school building standard and, on the basis of this result, conducted efficiency analysis of various heat pump systems. The conclusion according to synthetical analysis & evaluation can be summarized as follows. In case a heat pump system is introduced to a school building, it was deemed the investment in the early stage would increase, but the investment could be collected within 5~6 years through reduction of large operation expenses. Also, it was analyzed in case of terrestrial heat contracted heat mode using midnight electric power among heat pump systems, not only early investment but also operation expenses could be reduced to a great extent. Accordingly in case the system using terrestrial heat energy is applied to the school buildings that are to be newly built or repaired in the future, it will provide an object-lesson to students as well as contributing to energy saving.

• International Journal of Air-Conditioning and Refrigeration
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• v.6
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• pp.168-176
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• 1998

A simulation study was conducted to use city-water which is thermally regulated by unused energy as a heat source for urban dwellings. This study utilized multiple heat pump system using the city-water as a heat source and suggested a method of reducing the heat load of hot water supply. The simulation was done to calculate the energy savings at a dwelling for a year. The relation between the controlled temperature of city-water. and electric energy in all seasons was also investigated. Furthermore, it has been found that the controlled water system can lead to considerable energy savings and decrease environmental load such as sensible waste heat which otherwise would form heat islands.

• Journal of the Korean Institute of Gas
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• v.4 no.4 s.12
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• pp.13-19
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• 2000

Researches on unused energy are being continued because of the limited fossil fuel and the destruction of environment. Therefore this study was performed as follows The collectable amount of exhausted heat for an air-conditioning was calculated by the subway thermal environment prediction program. And the electric power needed by conventional heat source equipments was compared with one by unused heat source equipments when the exhausted heat was used by heat pump in heating and hot water supplying.