• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.782-787
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• 2008

The Kalina cycle simulation study was carried out for a preliminary design of a geothermal power generation system. The Kalina cycle system can be used for the utilization of a low-temperature heat sources such as geothermal and industrial waste heat that are not hot enough to produce steam. The sea/river water can be considered as a cooling media. A steady-state simulation model was developed to analyze and optimize its performance. The model contains a turbine, a pump, an expansion valve and heat exchangers. The turbine and pump were modelled by an isentropic efficiency, while a condenser, an evaporator and a regenerative heat exchanger were modeled by UA-LMTD method with a counter-flow assumption. The simulation results show that the power generation efficiency over 10% is expected when a heat source and sink inlet temperatures are $100^{\circ}C$ and $10^{\circ}C$ respectively.

• 한국인터넷방송통신학회논문지
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• 제19권6호
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• pp.73-77
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• 2019

본 논문에서는 냉매의 흡열 또는 응축열을 이용하여 저온의 열원을 고온으로 전달하거나 고온의 열원을 저온으로 전달하는 공기열원 히트 시스템을 설계 제작하였다. 히트펌프는 냉동 사이클에서 응축기 및 증발기를 기능이 전환가능한 밸브를 이용하며 따라서 난방시에 응축기 기능을 하는 열교환기가 냉방시에는 증발기 기능을 하도록 함으로써 냉난방을 구현할 수 있도록 하였다. 이를 위하여 저온의 열원을 고온으로 전달하거나 고온의 열원을 저온으로 전달하기 위한 체계가 개발되었다. 실험을 위하여 냉각 사이클에서 콘덴서와 증발기를 전환하는 기능으로 밸브를 사용하기 위한 히트펌프를 제작하였다. 그 결과 히트펌프시스템은 공기열원방법으로 개발되어졌으며 하나의 시스템으로 냉난방을 동시에 해결할 수 있는 에너지 절약 시스템을 설계하였다.

• 동력기계공학회지
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• 제18권5호
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• pp.42-47
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• 2014

In this paper, the cycle performance analysis for the COP of supercritical heat pump using various refrigerants is presented to offer the basic design data for the operating parameters of the system. The working fluids are R134a, R22, R32, R290, R600, R600a, R1270 and R744. The operating parameters considered in this study include superheating degree of evaporator, temperature of gas cooler inlet and outlet, compressor efficiency and evaporating temperature in the supercritical heat pump system. The main results were summarized as follows : Superheating degree, temperature of gas cooler inlet and outlet, compressor efficiency and evaporating temperature of supercritical heat pump system have an effect on the COP of this system. With a thorough grasp of these effect, it is necessary to design the supercritical heat pump using R134a. And, in comparison of COP of supercritical heat pump using various refrigerants, R32 and R600 is the highest, and R744 is the lowest among other refrigerants. From these results, it is confirmed that the COP of supercritical heat pump using R744 is higher than that using freon refrigerants such as R32 and R134a.

• 에너지공학
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• 제19권4호
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• pp.228-233
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• 2010

기존의 열풍건조기의 효율은 약 30% ~ 50%인 반면, 최적 설계된 열풍-열펌프 건조기 효율은 약 60% ~ 80% 수준이므로 에너지 효율향상과 에너지 절약을 이룰 수 있다. 외국의 여러 사례에서는 기존 대비 약 60% ~ 80%의 에너지를 절약할 수 있으며, 밀폐형 순환방법을 사용하여 건조공기에 포함될 수 있는 환경오염물질의 외부로의 유출을 최소화 할 수 있어 기존의 건조기에 비해서 환경문제에 적극적으로 대응할 수 있을 것을 판단된다. 본 논문에서는 이와 같은 특성을 가진 건조기에 적용하기 위한 고온 생산이 가능한 열펌프를 얻기 위하여 시스템의 사이클을 설계하고 시스템을 구축하여 목표 성능을 만족하는지 여부를 확인하였다. 본 연구에서는 열펌프 복합건조기 적용을 위한 고온용 열펌프 시스템을 설계하고 제작한 후, 성능평가를 수행하여 다음의 결론을 얻었다. (1) 고온생산을 위한 시스템 설계는 2사이클이 가장 우수한 것으로 나타났다. (2) 2사이클 시스템은 저단이 R134a를, 고단이 R124를 냉매로 사용할 경우 가장 적합한 것으로 나타났다. (3) 사이클 운전을 통하여 상용압력으로 간주되는 범위에서 R134a시스템은 $75^{\circ}C$, R124시스템은 $95^{\circ}C$ 생산이 가능한 것으로 나타났다. (4) 수냉식 2사이클 시스템의 성능 시험을 수행한 결과 목표성능을 상회하는 결과를 얻어 고온 생산이 가능한 열펌프 시스템의 설계 및 제작이 가능한 것으로 나타났다.

• 설비공학논문집
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• 제29권3호
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• pp.119-126
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• 2017

Recently, ground source heat pump systems are being used in buildings for cooling and heating to reduce greenhouse gas and save energy. However, ground source heat pump systems mainly use the vertical closed-loop geothermal system design rather than the open-loop geothermal system design. This is due to a lack of knowledge and few research feasibility studies. In this research, a dynamic thermal analysis numerical simulation based on a standard house model was conducted for an open-loop geothermal system. Based on heating load analysis results, the life cycle costs of a standard house using an open two-well geothermal system were analyzed and compared with a vertical closed-loop geothermal system, and a diesel boiler. As a result, it was found that using an open two-well geothermal system shows economic return on investment after three years.

• 설비공학논문집
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• 제16권2호
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• pp.158-166
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• 2004

The performance of a heat pump using $CO_2$ is predicted and analyzed by using a cycle simulation model developed in this study. Cycle simulations are conducted by varying design parameters and operating conditions with the applications of advanced techniques to improve system performance. The applied systems in the simulations are internal heat exchanger, expander, and 2-stage compression with intercooling. As a result, the applications of advanced techniques improve the heating and cooling performances of the transcritical $CO_2$ cycle by 8∼26％ and 20∼30％, respectively, over the basic cycle.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.363-369
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• 2008

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.40-43
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• 2006

Public demand for the heat pump system as a next generation energy equipment is increasing for its eco-friendly and cost-effective advantage. Many researches have been concentrated on how to calculate and develop its own efficiency, while the possible effect of the heat pump operation on the whole subsurface temperature distribution is relatively less considered, During the current study, subsurface temperature disturbance caused by seasonal surface temperature cycle in Busan area and general W-tube heat pump operation is simulated in 3-dimensional heterogeneous medium. It shows that subsurface deeper than 10m from the surface remains nearly unchanged throughout the 4 seasons and groundwater convect ion in highly permeable layer near the surface acts like a main path of heat plume from heat pump system, This implies the significance of detail descript ion in shallow sedimentary layer or highly permeable layer which plays an important role on the regional flow advection and heat transfer. Also, the effect of groundwater convection increases when the arrangement of the 2 injection pipes and 2 extract ion well is maintained parallel to groundwater flow. Therefore, more careful and detail investigation is required before installation and operation of heat pump system that it may not cause any possible change of microbial ecosystem in the shallow subsurface environment or 'contamination of temperature' for groundwater use as well as the loss of efficiency of the equipment itself. This can also help to design the optimized grouting system for heat pump.

• 설비공학논문집
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• 제7권2호
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• pp.234-248
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• 1995

A super-heat pump system composed of a suction line heat exchanger, low and high stage economizers, and a screw compressor is simulated to examine the energy performance and design options. CFC12, HCFC22, HFC134a, HCFC22/HCFC142b, HFC32/HFC134a, and HFC125/HFC134a are used as working fluids for comparison. The results indicate that the proposed system charged with appropriate mixtures is up to 33.4% more energy efficient than the normal system with CFC12. The performance of the super-heat pump system charged with mixtures was influenced by such factors as the temperature matching, heat source temperature difference, low stage economizer, and high stage economizer. The fluids with a larger liquid specific heat such as HFC134a would have more benefits when a suction line heat exchanger is installed. 40%HCFC22/60%HCFC142b mixture seems to be a good candidate to replace CFC12. On the other hand, 25%HFC32/75% HFC134a would be a good long term candidate to replace HCFC22.

• 한국지열·수열에너지학회논문집
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• 제12권3호
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• pp.24-32
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• 2016

Commercial buildings and institutions are generally cooling-dominated and therefore reject more heat to a borehole ground heat exchanger (BHE) than they extract over the annual cycle. Shallow ponds can provide a cost-effective means to balance the thermal loads to the ground and to reduce the length of BHE. This paper presents the analysis results of the impact of design parameters on the length of SWHE pipe and its application effect on geothermal heat pump (GHP) system using BHE. In order to analysis, we applied ${\varepsilon}-NTU$ method on designing the length of SWHE pipe. Analysis results show that the required pipe length of SWHE was decreased with the increase of approach temperature difference and with the decrease of pipe wall thickness. In addition, when the SWHE was applied to the GHP system, the temperature of BHE was more stable than that of standalone BHE system.