• 설비공학논문집
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• 제23권10호
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• pp.678-686
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• 2011

Simulation study on the operating characteristics in the solar hybrid R744 heat pump system for residential applications was carried out with heat pump operating temperature, outdoor temperature and solar radiation. As a result, collector operating time is decreased by 1.5 hours due to the increase of water temperature in the heat storage tank when the heat pump operating temperature rises. Heat pump operating time is reduced by 19.4% owing to the high temperature of a heat storage tank. Besides, indoor heating time is decreased from 10.3 to 5.5 hours as the indoor temperature increases from $3^{\circ}C$ to $11^{\circ}C$. In addition to, when the solar radiation rises from 10 to 20 MJ/$m^2$, the maximum outlet temperature of a solar collector is increased from $65^{\circ}C$ to $71^{\circ}C$.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.198-202
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• 2008

Refrigeration plants using absorption principles have been around for many years with initial development taking place over 100 years ago. Although the majority of absorption cycles are based on water-LiBr cycle, many applications exist where ammonia-water can be used, especially where lower temperatures are desirable. In both systems water is used as working fluid, but in quite different ways: as a solvent for the ammonia system, and as refrigerant for the lithium bromide system. This explains that the lithium bromide absorption system is strictly limited to evaporation temperatures above $0^{\circ}C$. The main industrial applications for refrigeration are in the temperature range below $0^{\circ}C$, the field for the binary system ammonia-water.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.99-102
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• 2008

The growth of domestic energy demand is rapidly increased for the industrialization and the improvement of the living standards. It is also recognised that the importance of the use of environmentally friendly energy and high efficient equipment. Ground Source heat pumps(GSHP) using earth as heat source or sink are outstanding environmentally friendly energy systems which have high thermal efficiency when compared to conventional heating and cooling system. So government employs a policy and increase investment for expanding renewable energy market volume. Especially is established a system for obligatory usage of renewable energy to achieve 5% renewable energy diffusion rate by 2011. And the market demand for the ground source heat pump is rapidly growing due to its strong advantages. However domestic situation usually have been depended on the import of ground source heat pumps. In this paper, the results of development of a ground source heat pump using refrigerant R410A are reported.

• 설비공학논문집
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• 제24권4호
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• pp.315-322
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• 2012

In these days, importance of HVAC system in office building is steadily growing in terms of thermal comfort and energy savings. As a energy efficient heating and cooling system, system air-conditioner which can be controlled distinctly and has a high COP is more widely adopted nowadays. However, the features and advantages of system air-conditioner were not reported well because system air-conditioner did not describe yet by conventional simulation methods such as TRNSYS, e-Quest, Energyplus, etc. In this study, by using the TRNSYS program which is able to show module implementation and building energy consumption analysis, system air-conditioner module will be proposed and validated through comparison between the simulation results and measurement results.

• 한국지열·수열에너지학회논문집
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• 제8권4호
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• pp.24-31
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• 2012

The Solar and geothermal energy have many advantage like low cost, non-toxic, and unlimited. But those the have very low energy efficiency. In this study, the theoretical study of performance in a sola-geothermal hybrid heat pump with operating conditions has carried out. As a result, as the solar radiation increases from 1 $MJ/m^2$ to 20 $MJ/m^2$, the heat pump operating time decreases by 19.5% from 18 times to 14.5 times and the heat pump heat decreases by 23%. Besides, the heating COP increases by 21.4% when the evaporator inlet temperature increases from $11^{\circ}C$ to $19^{\circ}C$. By adapting the geothermal system into a solar hybrid R22 heat pump, the system performance and reliability increases significantly for variable operating conditions during winter season.

• 설비공학논문집
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• 제12권3호
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• pp.258-266
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• 2000

Experimental investigation and cycle simulation of a capacity modulation of a heat pump system using a hydrofluorocarbon (HFC) refrigerant mixture, R32/134a as an alternative to R22, have been done. In the cycle simulation, the refrigeration system was operated by assigning the temperatures of the external heat transfer fluids with the heat exchangers generalized by an average effective temperature difference. Heating capacity, cooling capacity, and coefficient of performance (COP) of the system were investigated at several operating conditions. Experimental apparatus which had a refrigeration part and a composition changing part was built, and the performance of the heat pump system filled with R32/134a mixture was investigated. A gas-liquid separator was used in the experiment to change the composition by collecting the vapor and the liquid Phase separately, The mass fraction of the charged refrigerant in the heat pump system was 40/60 and 70/30 by weight percentage. The composition of the refrigerant with initial composition of 40/60 varied from 29/71 to 41/59 in the refrigeration cycle. For the refrigerant with initial composition of 70/30, the composition varied from 65/35 to 75/25.

• 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.

• 한국지열·수열에너지학회논문집
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• 제20권2호
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• pp.24-36
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• 2024

This study analyzed the feasibility of the air source heat pump in residential buildings based on operational performance and carbon emissions. The operational performance and carbon emissions were compared between a gas boiler and an air source heat pump by calculating the annual heating and hot water load based on the 21A and 36A models for actual residential buildings. For the operational performance of the air source heat pump, the lowest (2.3) and highest COP (5.9) were attained during the winter and summer seasons, respectively. The carbon emissions depend on the amount of energy consumed during operations. An air source heat pump consumed 65.10% and 65.4% less energy per year in the 21A and 36A models, respectively compared to the existing gas boiler. Consequently, for air source heat pump carbon emissions were also reduced by 13.3% and 15.1% per year for the 21A and 36A models, respectively. It shows the effectiveness of applying an air source heat pump compared to an existing gas boiler.

• 생물환경조절학회지
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• 제17권2호
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• pp.90-95
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• 2008

수직형에 비해 비교적 가격이 저렴하고 냉난방을 동시에 할 수 있는 농업시설에 적합한 10RT 규모의 수평형 지열히트펌프 시스템을 $240m^2$ 면적의 온실에 설치하고, 이 시스템의 냉방성능을 분석하였다. 응축기 출구온도가 $40^{\circ}C$에서 $58^{\circ}C$로 상승함에 따라 소비전력은 11.5kW에서 15kw로 상승하였으며, 고압이 1,617kpa에서 2,450kPa로 변화하였다. 냉방성능계수는 지중온도 $25.5^{\circ}C$에서 2.7 수준이었으며 지온이 상승함에 따라 하강하여 $33.5^{\circ}C$에서 2.0 수준이었다. 또한 온실 내부로부터 흡수하는 열량(냉방열량)은 같은 지중온도 수준에서 각각 28.8kW, 26.5kW이었다. 가동 8시간 후 지열교환기가 설치된 60cm깊이의 지온은 $14.3^{\circ}C$가 상승하였으며 150cm는 $15.3^{\circ}C$가 상승하였다. 반면 지열교환기가 매설되지 않은 60cm 깊이는 2.4, 150cm 깊이는 $4.3^{\circ}C$의 지온상승을 보였다. 열매 체유가 지열교환기를 통과한 후 평균 $7.5^{\circ}C$의 온포가 하강하였으며, 토양온도가 평균 $27.5^{\circ}C$ 수준에서 토양으로 방출하는 열량은 평균 46kw로 지중열교환기의 단위 길이 당 약 36.8W의 열량을 방출하는 것으로 분석되었다. 팬코일 유닛이 온실로부터 흡수하는 냉방 열량은 평균 28.2kW이었으며, 열매체유의 온도는 $4.2^{\circ}C$ 상승하였다. 축열조내 열전달매체유의 온도가 $26.0^{\circ}C$에서 $2.0^{\circ}C$까지 하강하는데 3시간이 소요되었으며, 평균 축열율은 29.7kW, 총 축열량은 321MJ이었다. 또한 $2.0^{\circ}C$까지 냉열을 축열한 후 $25.4^{\circ}C$까지 방열되는 시간은 외기온이 평균 $28.5^{\circ}C$일 때 4시간이었고, 총 313.0MJ의 에너지가 방열되었으며, 이때 평균 방열율은 21.7kW인 것으로 분석되었다.

• 생물환경조절학회지
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• 제22권4호
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• pp.328-334
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• 2013

본 연구에서는 온실 내부의 태양 잉여열과 외부의 공기열을 선택적으로 열원으로 이용함으로써 히트펌프의 성능을 향상시키고, 온실의 환기 지연을 통해 이산화탄소 시용비용을 절감할 수 있는 온실 공조시스템을 개발하고자 하였다. 본 시스템의 축열 과정은 태양 잉여열을 이용하는 내부순환모드와 외기열을 이용하는 외부순환모드가 온실 내부온도에 따라 자동으로 절환되도록 구성하였으며, 히트펌프 가동, 축열모드 절환, 난방 가동을 위한 6개의 온도값을 입력함으로써 축열과 난방이 자동으로 수행되도록 설계하였다. 단동온실을 대상으로 무환기 조건에서 기초시험을 수행한 결과, 태양 잉여열을 이용한 축열은 약 11시부터 시작되어 평균 3시간 30분 정도 유지되었으며, 주간의 온실 내부온도는 환기를 수행하지 않음에도 대부분 약 $20{\sim}28^{\circ}C$ 범위를 유지하였다. 주간 내부순환모드에서 시스템의 난방성능계수는 약 3.35로 야간 외부순환모드의 2.46 및 주간 외부순환모드의 2.67에 비해 각각 36% 및 25% 향상됨을 확인하였다. 본 시스템의 개선사항으로 태양 잉여열의 효율적 이용을 위해 축열조 관리온도를 상승시킬 수 있는 고효율 히트펌프의 적용이 필요하며, 온실의 무환기 운용에 따른 과습환경의 조성을 방지하고 태양 잉여열 수준이 높은 시기에 온실의 온도상승을 방지하기 위해 강제환기를 운전모드에 추가할 필요가 있는 것으로 판단되었다.