• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1226-1231
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• 2009

This paper presents operating characteristics of internal heat exchanger(IHX) for $CO_2$ geothermal heat pump in the heating mode. Mass flow rate of $CO_2$, inlet temperatures of $CO_2$ at high and low pressure side were selected as main effect factors by using fractional factorial DOE(Design of Experiments). And RSM(Response Surface Method) was used in optimization phase. The results show that heat transfer rate of IHX increases when either inlet temperature of low pressure side decreases or inlet temperature of high pressure side increases. Effectiveness of IHX increases with increasing of inlet temperature of either high pressure side or low pressure side. Finally, performance contour map was provided over the operation ranges of the main design factors.

• KIEAE Journal
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• 제14권2호
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• pp.29-36
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• 2014

The ground source heat pump (GSHP) system has attracted much of attention, because of its stability of heat production and the high efficiency of the system. Performance of the heat exchanger is dependent on the soil temperature, the ground thermal conductivity, the operation schedule, the pipe placement and the design temperature. However, in spite of the many variables of these systems, there have been few research on the effect of the systems on system performance. In this study, analysis of the heat exchange rate according to soil temperature and grout material was conducted by numerical simulation. Furthermore, the heat distribution around the ground heat exchanger was presented on the different conditions of grout and underground temperature by the simulation.

• 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.

• 설비공학논문집
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• 제25권5호
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• pp.225-232
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• 2013

Heat pump systems have been widely adopted in buildings for cooling and heating, due to their higher energy efficiency. Recently, the demand for hot water supply from the heat pump system has been increasing. To increase the water supply temperature with higher system efficiency and reliability, a heat pump water heater adopting cascade cycle was investigated in this study. The cascade heat pump water heater consisted of a low-stage cycle using R410A, and a high-stage cycle using R134a. A simulation program for the cascade heat pump water heater was developed, and verified by comparison with experimental data. The performance of the cascade heat pump water heater was optimized, by varying the compressor rotating speeds of the low- and high-stage cycles. At low ambient temperatures, the performance of the cascade cycle was compared with that of the single-stage cycle. The system efficiency of the cascade cycle was higher than that of the single-stage cycle, showing a lower compression ratio and compressor discharge temperature.

• 융합신호처리학회논문지
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• 제21권4호
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• pp.177-182
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• 2020

친환경적이고 에너지 절약적인 난방 방법으로 히트펌프에 대한 관심이 높아지고 있다. 특히, 저온 지역에서 난방이 가능한 히트펌프를 개발하기 위해 실외기 표면에 서리가 발생하지 않도록 하는 연구가 많아지고 있다. 즉, 온도가 낮은 지역에서 히트펌프를 통해 난방을 할 경우 실외기 표면에 서리층이 형성되어 전열성능을 떨어뜨려 난방능력을 감소시키는 것이 일반적이다. 따라서 본 연구에서는 히트펌프의 실외기에 유입되는 습공기의 수증기를 흡착식 제습시스템을 부착하여 제거하고자 한다. 본 연구를 통해 저온지역에서 가장 효과적인 제습방법을 제시할 수 있을 것으로 판단된다. 그리고 히트펌프의 실외기 전면에 흡착식 제습시스템을 부착하여 에너지 효율이 높은 히트펌프를 개발할 수 있을 것으로 사료된다.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.37-44
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• 2008

The global warming potential (GWP) of $CO_2$ refrigerant is 1/1300 times lower than that of R134a. Furthermore, the size and weight of the automotive heat pump system can decrease because $CO_2$ operates at high pressure with significantly higher discharge temperature and larger temperature change. The presented $CO_2$ heat pump system was designed for both cooling and heating in fuel cell vehicles. In this study, the performance characteristics of the heat pump system were analyzed for heating, and results for performance were provided for operating conditions when using recovered heat from the stack coolant. The performance of the heat pump system with heater core was compared with that of the conventional heating system with heater core and that of the heat pump system without heater core, and thus the heat pump system with heater core showed the best performance among the selected heating systems. On the other hand, the heating performance of two different types of coolant/air heat pump systems with heater core was compared each other at various coolant inlet temperatures. Furthermore, to use exhausted thermal energy through the radiator, experiments were carried out by changing the arrangement of a radiator and an outdoor evaporator, and quantified the heating effectiveness.

• 설비공학논문집
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• 제17권1호
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• pp.39-46
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• 2005

The present study concerns an experimental study of a R-22 heat pump system consisted of liquid and liquid heat exchangers. The test was performed for various systems of a single-, tandem-, and two stage-cycle at the same environmental conditions of temperature. Various experiments of the heat pump system were peformed to compare the heating capacity and COP, when the outdoor temperature is near $-15^{\circ}C$ and the indoor temperature is $20^{\circ}C.$ As the results of the present study, the system of Tandem(parallel) cycle showed the best heating performance, while the discharge temperature of refrigerant was too high. In case of the system of two stage cycle, the performance characteristics were significantly improved by employing the inter cooler.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.996-1001
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• 2009

The purposes of this work were suggested and validated the methods of heat recovery from dyeing wastewater exhausted in Sihwa and Banwol dyeing industrial park. We analyzed the present conditions of heat supplies and demands. So it was made a selection of the system combined heat exchanger for waste heat recovery and the high temperature heat pump. We decided the specifications of the heat recovery facilities. After this, economical assessment is performed to this system. The payback periods are within 4 years, 20 years and 5 years in case of K company, S company and A company. In addition, when they are produced the heat of same capacity, quantities of pollutants from used fuels were calculated.

• 한국지하수토양환경학회지:지하수토양환경
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• 제14권4호
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• pp.10-14
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• 2009

본 논문은 지열시스템의 설치 시 사용되는 그라우트와 운영에 따른 수온변동이 유발할 수 있는 미생물학적 영향을 실내실험을 통해 살펴보았다. 시료는 지열히트펌프가 아직 가동되지 않는 관정(한방병원)과 지열 히트펌프가 가동 중인 곳(창업보육센터)에서 채취하였다. 실험에 사용한 그라우트는 볼클레이 벤토나이트로 나트륨(Na)계이며 Real-time PCR을 사용하여 각 시료에서 추출된 총 유전자 DNA 중 세균이 가지고 있는 16S rDNA를 정량함으로써 전체 세균의 양을 평가하였다. 실험 결과 지열히트펌프가 가동 중인 지하수에서 총 세균양이 가장 많았으며 벤토나이트를 주입하면서 세균수가 증가하는 경향을 보였다. 한편 그라우트 및 수온영향을 보다 명확하게 파악하기 위해서는 장기적인 현장모니터링이 요구된다.

• 한국지열·수열에너지학회논문집
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• 제17권2호
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• pp.11-19
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• 2021

In this study, combined heat source heat pump system was implemented with 4 single heat source heat pumps each applied with a geothermal source and a water source. Five cases (Case1~Case5) were configured to conduct a performance comparison and analysis of the combined heat source heat pump system. First of all, as a result of analyzing the heat source, the case when 4 ground heat sources were applied (Case1) showed a uniform EST(Entering Source Temperature) distribution throughout the year since it is less affected by outside air compared to the case when 4 water heat sources were applied (Case5). In both winter and summer, the ground heat source maintained higher EST than the water heat source. Therefore, the system with high ratio of geothermal sources is advantageous for heating, and with high ratio of water heat sources is advantageous for cooling.