• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.8
• /
• pp.797-802
• /
• 2012

In this study, the potential performance enhancement in a dual heat pump system through series operation was investigated by a comparison between the performance for parallel and series operation for a heating supply temperature of $60^{\circ}C$. To compare the performance of each configuration fairly, the heat transfer surface area of the heat exchangers was fixed. The inlet temperatures and the flow rates of the heat source and the load were also fixed. In addition, the heat transfer and pressure drop characteristics of the working fluids were considered to achieve a more realistic comparison. The results show that the heating coefficient of performance (COP) of the series configuration is approximately 5% higher than that of the parallel configuration under the simulation conditions considered in the present study.

• Journal of Energy Engineering
• /
• v.5 no.2
• /
• pp.183-192
• /
• 1996

This paper presents a numerical model of the optimal operation pattern of the CHP system built for duel-purpose of power generation and district heat production. The model can be differently formulated in accordance with the view of planner: society, electric utility or district-heating company. Here, the operation pattern of the system components and the effect of heat price are of major interest in the study. From the case study, it was found that the optimal use of auxiliary heating equipment is very important to achieve the minimum societal cost. And, the multi-step heat pricing scheme is desirable to induce the voluntary behavior of both companies towards the societal optimal pattern.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2002.07a
• /
• pp.310-315
• /
• 2002

겨울철 저온기에 온실의 작물재배는 많은 에너지가 소요되어 저온기의 에너지비용을 최소화하는 것이 온실의 운전비용의 절감과 이용효율이 증대되어 농가소득을 높일 수 있다. 저온기에는 작물의 수확량이 적정 온도조건의 80%수준으로 최소 에너지 투입방법 기술을 개발하여 수확량을 증대시킬 필요가 있다. 기존의 난방방법인 온수보일러는 온도유지 안정성은 좋으나 시설비용이 많이 들고 온풍난방은 설치비용은 저렴하나 온도 유지안정성이 다소 떨어지는 단점이 있다. (중략)

• Proceedings of the KAIS Fall Conference
• /
• 2010.05b
• /
• pp.1123-1126
• /
• 2010

본 연구에서는 외기온습도에 따른 히트펌프 칠러의 난방성능을 조사하고자 하였다. 난방표준 온도조건에서 건구온도 및 습구온도 변화에 따른 히트펌프 칠러의 난방능력과 COP를 획득하기 위하여 항온항습 챔버와 항온수조를 사용하였다. 실험은 건구온도 $7^{\circ}C{\sim}17^{\circ}C$, 상대습도 67%~87%에서 수행하였다. 외기온도가 증가함에 따라 난방능력은 약 27%, COP는 약 28% 증가하였지만, 상대습도 증가에 따른 난방능력과 COP의 변화는 거의 없었다. 따라서 난방운전 시 건구온도의 영향은 크고, 상대습도의 영향은 미미함을 알 수 있었다.

• Nuclear industry
• /
• v.10 no.7 s.89
• /
• pp.84-85
• /
• 1990

• Nuclear industry
• /
• v.11 no.4 s.98
• /
• pp.60-63
• /
• 1991

• Journal of Energy Engineering
• /
• v.21 no.2
• /
• pp.144-151
• /
• 2012

A district heating system produces thermal energy and supplies it to a large region. District heating systems can provide higher efficiencies and better pollution control than localized boilers. The heat generated by a district heating system is distributed to the customer via a network of insulated pipes. For the optimal operation of a district heating system, it is important to predict the distributions of pressure, flow rate and temperature of heating fluid within the network of pipes at various operating conditions. In this work, a mathematical modeling was performed to predict the dynamic hydraulic-thermal behaviors of heating fluid in the network of pipes for a district heating system. The mathematical model accounts for the conservations of mass, momentum and energy. In order to verify the validity of modeling, the modeling results were compared with the monitoring data of Gang-nam Branch of District Heating.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.2
• /
• pp.573-577
• /
• 2013

Heat pumps come into wide use because high energy efficiency can be obtained and diverse heat sources like geothermal heat, waste heat and air are available. It is necessary for an air source heat pump to defrost in order to remove frost on the surfaces of an outdoor heat exchanger. It is impossible for continuous heating if reverse cycle operation is used as defrosting method, furthermore it causes the degradation of COP. In this study an fin-tube heat exchanger with three rows was used as an outdoor coil. One row among three rows of the heat exchanger was used like a condenser in order to remove frost on it, the others were used as evaporator to accomplish continuous heating. Each row was switched in order from a condenser to an evaporator in specified time interval. Tests were carried out during minimum 180 minutes at the defrost-heating test condition(dry bulb temperature $2^{\circ}C$, wet bulb temperature $1^{\circ}C$) described in KS C 9306. Time-averaged COP was about 20% higher than that of conventional defrosting method.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.16 no.5
• /
• pp.463-476
• /
• 1987

주기적으로 작동하는 흡수식 장치가 부착된 직접 연소식 고효율 난방기기를 특정 공간 난방 목적으로 설계하여 제작하였다. 작동 유체는 메타놀/물-리치움브로마이드이다. 네개의 구성품으로 된 이 기기에는 동작부품이 없다. 제 1 시제품의 결과와 경험에 기반을 두고 개선형 시제품을 설계, 제작하였다. 현재까지 발생기-응축기 모듈이 설치되어 보일러 운전모드 결과가 확립되어 있다. 또한 난방기기의 경제성과 작동 유체의 안정성 연구가 중요한 부수 조건을 확립하기 위하여 수행되고 있다.

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.11a
• /
• pp.381-389
• /
• 2005

우리나라 에너지소비의 25%이상을 차지하는 건물냉난방부문의 에너지절약을 위해 에너지효율이 높은 것으로 나타난 지열냉난방시스템의 보급이 필요하다. 이에 지열냉난방시스템 실증연구를 통해 사무용건물에 지열냉난방시스템을 설계 및 적용하고 냉난방운전을 실시하였다. 실증연구 결과 지열냉난방시스템은 우리나라의 기후 및 지질조건에 매우 적합하며 냉방운전의 경우 COP가 평균 4.23$\sim$5.49, 난방운전의 경우 COP가 평균 3.32$\sim$4.44를 나타내었다. 실증연구를 통해 사무용건물의 지열냉난방시스템의 설계 및 시공능력을 확보함에 따라 향후 보급에 기여하고자 한다.