• 설비공학논문집
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• 제23권2호
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• pp.95-102
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• 2011

A ground loop heat exchanger in a ground source heat pump system is an important unit that determines the thermal performance of a system and its initial cost. A proper design requires certain site specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This study was performed to investigate the effect of some parameters such as borehole lengths, various grouting materials and U tube configurations on ground effective thermal conductivity and borehole thermal resistance. In this study, thermal response tests were conducted using a testing device to 9 different ground loop heat exchangers. From the experimental results, the length of ground loop heat exchanger affects to the effective thermal conductivity. The results of this experiment shows that higher thermal conductivity of grouting materials leads to the increase effective thermal conductivity from 22 to 32%. Also, mounting spacers have increased by 14%.

• 한국산학기술학회논문지
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• 제19권12호
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• pp.924-930
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• 2018

본 연구의 목적은 수소연료전지 자동차의 난방부하 대응을 위한 스택 냉각수를 활용하여서, 전동식 히트펌프 시스템에 대한 난방성능 특성을 다양한 운전조건 변화에 대해서 고찰하는 것이다. 냉각수와 냉매(R-134a)와의 열교환을 위해서 판형열교환기를 적용하였고, 전동식 히트펌프 시스템에 적용되는 실내열교환기 입구의 공기온도와 압축기 회전수를 변화시키면서 난방 성능 특성을 분석하였다. 실내열교환기 입구 공기 온도 변화에 대해서 난방 성능은 거의 동일한 결과를 보이고 있는데, 이는 입출구 온도차와 공기 측 밀도의 변화가 균형을 이루었기 때문으로 판단된다. 반면, 히트펌프 시스템 효율(COP)의 경우, 난방 성능은 온도변화에 따라 동일하였지만, 유량 변화로 인하여서, 압축기 소모동력이 감소하였기 때문에, 실내열 교환기 입구 온도가 감소함에 따라서, 시스템 효율은 증가하는 경향을 보이고 있다. 추가적으로, EEV개도가 45%정도까지 열리는 구간에서는, 압축기 소모전력 감소하였기 때문에, 시스템 효율이 증가하였고, 그 이후에는 동일한 시스템 효율을 유지하는 것을 알 수 있었다. 압축기 회전수 변화 시에는 난방성능이 증가하면, 시스템 효율은 감소하는 경향을 보여주고 있다. 이러한 원인은 압축기 회전수 증가에 따른 유량의 증가로 판단된다. 향후, 열원으로 사용하는 냉각수에 대한 운전조건을 변화시켜가면서, 난방성능 특성을 분석하여, 전동식 히트펌프의 난방부하 대응을 위한 제어 방안을 연구하고자 한다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 동계학술발표대회 논문집
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• pp.60-60
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• 2006

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 하계학술발표대회
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• pp.202-202
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• 2005

• KIEAE Journal
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• 제17권3호
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• pp.119-124
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• 2017

Purpose: Groundwater heat pump (GWHP) system has high coefficient of performance than conventional air-source heat pump system and closed-loop type geothermal system. However, there is problem in long-term operation that groundwater raise at the diffusion well and reduced at the supply well. Therefore, it is necessary to accurately predict the groundwater flow, groundwater movement and control the groundwater level in the wells. In this research, in consideration of hydrogeological characteristic, groundwater level and groundwater movement were conducted analysis in order to develop the optimal design method of the two-well system using the pairing pipe. Method: For the optimum design of the two-well system, this research focused on the design method of the pairing pipe in the simulation model. Especially, in order to control the groundwater level in wells, pairing pipe between the supply well and diffusion well was developed and the groundwater level during the system operation was analyzed by the numerical simulation. Result: As the result of simulation, the groundwater level increased to -2.65m even in the condition of low hydraulic conductivity and high pumping flow rate. Consequently, it was found that the developed system can be operated stably.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
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• pp.591-594
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• 2005

Geothermal energy becomes to be one of the promising energy sources. In this study, technology using water thermal energy from riverbank filtration system(including alluvial and riverbed deposit) is reviewed and checked as an energy resources. The objects of this study are (1) long-term monitoring of alluvial and riverbed sites, (2) preliminary design of cooling and heating system at riverbank filtration facility, and (3) calculation of potential groundwater heat energy, including riverbank filtration system. Measuring data of alluvial and riverbank filtration show slight fluctuations comparing to temperature of atmospheric air which indicates that groundwater obtained from the riverbank filtration system have a sufficient potential as a source of cooling and heating energy.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.794-800
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• 2008

Due to high oil prices and global warming problems, researching an alternative energy source and decreasing the energy usage will be the key in the future. Unlike other alternative energy sources, geothermal energy is less dependent on the surrounding environment. Geothermal energy is the ideal energy source for buildings due to the simple and space saving installation. The system is semi permanent once it is installed and this will help reduce the energy usage in controlling the climate in buildings. Geothermal energy does not emit carbon dioxide and other gases that are harmful to the environment. Therefore geothermal energy will be the key in solving high oil prices and a decrease in fossil fuels by applying the geothermal energy system to detached house to counter future energy crisis.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.58-63
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• 2009

A ground-loop heat exchanger for the ground source heat pump system is the core equipment determining the thermal performance and initial cost of the system. The size and performance of the heat exchanger is highly dependent on the ground thermal properties - the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. Nowadays, precast concrete piles using steel reinforced precast concrete piles - energy piles - are used to reduce the installing cost of the ground-loop heat exchanger. We were carried out some tests to investigate the effects of some parameters such as borehole length, grouting materials and U-tube configuration of the energy piles. 4 concrete piles, each measuring $250mm{\sim}400mm$ in diameter and approx. 10m in length, and rigged with single spiral and 3 U-tube loop of $16mm{\times}2.3mm$ PB piping. The thermal response tests were conducted using a testing device for 4-different ground-loop heat exchangers. During the heating period, the energy piles absorb the heat of 0.89kW to 1.37kW.

• 설비공학논문집
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• 제26권2호
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• pp.86-90
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• 2014

It is important to select an optimal capacity for equipment, because the initial cost of new and renewable energy system is more expensive than that of exiting system. An optimal equipment and enhanced rate of operation can be selected, to analyze the cooling and heating load of buildings. In this study, seawater heat pump system in the Jeju area will be applied, by the heat source equipment of district heating. The loads of buildings are analyzed from existing researches, to select optimal capacity of equipment. Also, an optimal rate of building use will be set up, from a combination of buildings.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.429-433
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• 2007

Cement mortar and concrete can be used as grouts but problems regarding shrinkage and the discord of coefficients of thermal expansion between grouts and HDPE pipes has to be solved. Thermal conductivities of wet condition two times larger than those of dry condition, except for pure cement mortar. The addition of sand into the cement grouts greatly increases the thermal conductivity. The addition of bentonite into the cement grouts reduces thermal conductivity thus reducing the density. Bentonite grouting must be used only below the groundwater table since bentonite grouts possesses high shrinkage property in dry condition. The addition of sand prevents the shrinkage of bentonite grouts. Bentonite manufactured in Korea can be used since they possess similar thermal conductivities with imported products. The addition of sand into the bentonite grouts greatly increases the thermal conductivity.