• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.199.1-199.1
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• 2010

The purpose of this study is on the thermal performance evaluation of KIER Zero Energy Solar House-II, called ZeSH-II which can be sustained with the support of a very few energy. This ZeSH-II was designed and constructed in the end of 2009 to develop for the goal of 70% self-sufficiency. Several key technologies like as the super insulation, high performance window, wast heat recovery system as well as solar power and thermal system and geo-source heat pump wear used for this ZeSH-II. The monitering of ZeSH-II was conducted for six months from November 2009 to April 2010. The monthly energy consumption was calculated based on the monitering results. As a result, the ZeSH-II shows that the energy self-sufficiency during six months(from oct. to apr.) is about 80% which is higher than that of the target.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.624-629
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• 2008

The problem was derived from a simple process in solar water heating system. In a new designed electro less separated system we involved a kind of bubble pump. Beside experiment analysis, numerical simulation of the core of bubble pump is also very important. In this paper we investigated the motion of bubbles in vertical tube in two dimensions. The heat and mass transfer was simulated. The result of numerical simulation give a significant help of optimize design of bubble pump.

• KIEAE Journal
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• 제16권6호
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• pp.167-172
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• 2016

Purpose: The solar water heater with natural circulation has been used for several decades in the world as it is automatically operated without a pump and controller and is easy to maintain and repair. After the subsidy was offered from 2012, the solar water heater with natural circulation is becoming increasingly popular in Korea. Recently, the development of a wall-integrated solar water heater, which improves the applicability of buildings and prevents the overheating in the summer, is being developed. On the other hand, the design and performance evaluation data of solar water heaters are very inadequate, and analysis of heat and flow is required to develop a new type of solar water heater. Method: Therefore, in this study, we proposed a new simplified system analysis model that reflects heat and pressure loss from the test results of KS B ISO 9806-1 (Solar collector test method), assuming that the collector is a simple pipe system, the validity of which was verified through experiments. Result: As a result, first, the RMSE of the system circulation flow rate and the average temperature of the inlet and outlet of the collector according to the experimental results and the simulation are 0.05563 and 0.88530, respectively, which are very consistent. Secondly, the mass flow rate is increased linearly with the increase of the solar radiation, and the mass flow rate is 0.0104 ~ 0.0180kg/s in the range of $200{\sim}380W/m^2$ of solar irradiance. Compared with the test flow rate 0.0764kg / s of the test collector, it showed a level of less than 20%.

• 태양에너지
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• 제18권1호
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• pp.69-79
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• 1998

This paper is concerned about the performance of HCFC22 alternative refrigerants used in heat pumps and industrial chillers. A water-to-water breadboard heat pump with counter-current heat exchangers and a hermetic compressor was built to carry out the experiments with various refrigerants. For each test, more than 40 temperatures, 4 pressures, power input, mass flow rates of the heat transfer fluids were measured. Refrigerants tested were HCFC22, R290(Propane), an azeotrope of 45%Propane/55%R134a mixture, and a nonazeotropic mixture of Calor 50. All tests were conducted under ARI test A condition. It is found that the COP and capacity of propane were 18% and 2.5% higher than those of HCFC22 while the COP and capacity of 45%Propane/55%R134a mixture were 3.5% and 5.3% higher than those of HCFC22 respectively. Also the COP and capacity of Calor 50 were 17% and 7.8% higher than those of HCFC22. Compressor discharge temperatures of alternative refrigerants were roughly $35^{\circ}C$ lower than that of HCFC22 indicating that these refrigerants are good from the view point of compressor reliability. The charging amounts for the alternative refrigerants were reduced by 40-60% as compared to that of HCFC22. Overall, it can be said that hydrocarbon containing alternative refrigerants are excellent in thermodynamic performance but should be used with considerable care due to their flammability.

• 한국축산시설환경학회지
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• 제9권2호
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• pp.69-78
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• 2003

태양열을 동력원으로 하여 열에너지를 동력으로 변환, 물을 양수할 목적으로 저온 상변화물질인 펜탄을 작동물질로 하는 에너지변환장치를 제작하여 실험하였다. 장치는 각부의 크기를 그 기능과 상호작용 원리에 따라 논리에 맞게 최적 설계하였다. 장치의 제작 후 실험을 통하여 그 운전 특성을 분석하여 성능향상에 필요한 자료를 획득하고자 하였다. 작동물질인 펜탄을 가열하는 탱크 내부의 온도는 사이클 경과시간에 따라 약 $40­86^{\circ}C$ 범위에서 변동하고 있었으며, 물탱크내 온도 약 $23­24^{\circ}C$, 공기탱크 내 온도 $22­23.5^{\circ}C$ 범위에서 비교적 일정하게 유지되고 있었다. 응축기내의 온도와 냉각수출구 온도는 냉각수입구 온도수준에 따라 정의 상관관계로 변하고 있는 것을 알 수 있었으며, 또한 열 교환 능력도 냉각수 온도수준이 낮을수록 커진다는 것을 확인하였다. 물탱크 내 온도와 응축기내 온도가 상당히 차이가 나므로 물탱크와 응축기와의 연결거리를 최소화하고 연결파이프 크기를 큰 것으로 하여 내부물질이동 저항을 줄이는 것이 바람직하다는 것을 알 수 있었다. 실험 중 양수량은 1.6­2.4 liter로 나타났으며, 냉각시간의 수준에 따른 물탱크내의 흡입물높이 상승은 차이를 나타내지 않았다. 응축기로부터의 냉각수 배출파이프가 연장되지 않은 경우 냉각수 유량이 5.9 liter/min 이었으나 연장파이프가 있을 때는 2.3 liter/min으로 나타났다. 이러한 현상에서 양수하는 물의 온도가 낮고 유량이 부족한 경우에는 연장파이프를 이용하는 것이 좋고, 냉각수치 양은 풍부하지만 그 온도가 낮지 않은 경우에는 연장파이프를 이용하지 않는 것이 좋다는 사실을 알 수 있다. 실험에서의 응축기내 냉각수의 최대 열교환량은 95.75 kJ/min로 나타났다. 작동물질가열탱크와 기액 분리탱크 내의 압력은 0.13­0.14 MPa.a, 물탱크와 응축기내의 압력은 약 0.11 MPa.a정도로 나타났다.

• 한국태양에너지학회 논문집
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• 제32권5호
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• pp.25-30
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• 2012

Ground source heat pumps(GSHPs) are among the most efficient and comfortable heating and cooling technologies currently available, because they use the earth's natural heat to provide heating, cooling, and often, water heating. And Building Integrated Geothermal System(BIGS) is one of GSHPs which install ground heat exchanger(GHE) in energy pile without borehole to save the investment cost. Therefore, the experiment is to evaluate the heating performance of BIGS in Korea. The experimental results indicate that the average heat pump COP and overall system's COP values are approximately 4.4 and 3.0 in one week. This study shows that the BIGS could be used for heating in Korea.

• 한국태양에너지학회 논문집
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• 제27권2호
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• pp.11-17
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• 2007

This study evaluates the seasonal performances of the horizontal-type geothermal heat exchanger(HGHEX) installed into the foundation slabs of the complex building located at Seoul. The geothermal system is consisted with totally 31,860m long HGHEX, 16 GSHPs (Ground-source Heat Pump) and 8 circulation pumps. This system supplies cooling and heating to the lobby(F1) and the common spaces(BF1). The average heat exchange temperature differences are $2.7^{\circ}C\;and\;2.5^{\circ}C$ in the summer, $1.5^{\circ}C\;and\;0.5^{\circ}C$ in the winter for the F1 and BF1 respectively. From these results, approximately 400Gcal and 180Gcal of geothermal energy are assumed to have been used during the summer and winter seasons respectively. As a conclusion, the geothermal system is reviewed as a effective utility for heating and cooling at the point of seasonal performances.

• 한국태양에너지학회 논문집
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• 제33권1호
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• pp.57-65
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• 2013

The temperatures with the ground depth, the positions of circulation water in ground heat exchanger were measured and thermal diffusion characteristics with the distances of the direction normal to the borehole was analysed. The deeper the depth of ground, the less the influences of outdoor temperature, but below 10m of ground, there was no influences of ground temperature. When the depth of trench pipe was below the depth of 2m, there was no influence. In the ground of 10m when the distances between the pipe and the other places were above 0.5m, the variations of temperature were less than $1.6^{\circ}C$ and above 2.5m they were less than $0.1^{\circ}C$. When the distances of bore hole were above 5m, there were no. influences of the nearest ground heat exchanger.

• 한국태양에너지학회 논문집
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• 제35권1호
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• pp.81-87
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• 2015

Recently, in order to prevent increasing energy usages in the international community, many countries have attempted to develop the innovative renewable energy systems. Among the renewable energy systems, Ground source heat pump(GSHP) system which supply the heating, cooling and hot water in the building has been attracted by its stability of heat production and high efficiency. However, the initial drilling costs become very expensive and the construction period takes longer the other systems, because GSHP system needs more than 100 m depth drilling. In this study, in order to reduce initial costs of the GSHP, the building integrated geothermal system using the horizontal heat exchanger was developed. The heating and cooling load in the standard housing model was calculated by a simulation and the system design capacity in the high-rise apartment was decided by the total load. Based on the system design capacity, the high-rise apartments were applied to a BIGS and vertical GSHP system and there are analyzed about initial costs. In the result, the initial cost of BIGS could reduce 24% of the initial cost of the vertical GSHP system.

• 한국농공학회논문집
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• 제51권6호
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• pp.45-52
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• 2009

This study was conducted in the process that the basic plan of the formation of the thermal energy complex in the Iwon reclaimed land of Taean was being made. Targeting for the large-sized greenhouse to be made in this area, it examined the cooling and heating load and the amount of ventilation, and also analyzed the economic efficiency of heating. The research results are as per the below: The minimum ambient temperature of this area was measured on January 7, 2001, which was $-18.7^{\circ}C$, and the maximum ambient temperature of this area was measured on July 24, 1994, which was $36.7^{\circ}C$. The maximum heating load was 39,011 MJ/h, but the date when the maximum heating load was not consistent with the date when the minimum temperature was measured. The maximum cooling load was 88,562MJ/h, It was approximately 2.3 times of the maximum heating load, which was measured at 14:00 hours on September 4, 2000. The maximum amount of ventilation heat was 138,639MJ/h. Assuming the rate of solar heat use as 10%, 20%, 50%, and 100%, the total sum of cost-benefit would be ￦-193,450,000, ￦-634,930,000, ￦-3,372,960,000, and ￦-9,850,420,000, respectively 20 years later. The break-even point of the geothermal heat pump would be about 4 years for 10% use, about 3 years for 20% or 50% use, and approximately 6 years for 100% use. It was found that 50% use would be most advantageous. In case two systems are combined, the break-even point will be 10 years, 8 years, and 11 years respectively.