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

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.1141-1144
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• 2010

본 연구에서는 난방운전시 저온 및 착상 조건에서 히트펌프 칠러의 성능을 조사하고자 하였다. 실험은 항온항습 기능을 가진 공기엔탈피 방식의 칼로리미터와 항온수조를 사용하여 수행되었으며, 실외온도조건을 설정한 후에 히트펌프 칠러의 성능을 실험으로 측정하였다. 외기조건이 $-7^{\circ}C$에서 $-15^{\circ}C$까지 변화함에 따라 시스템의 성능과 COP는 표준온도 조건의 실험값 보다 약 48~87%까지 감소하였다. 착상 실험에서는 시간 변화에 따라 출구수온이 표준온도를 기준으로 74% 감소하였다. 본 연구로부터 히트펌프 칠러의 설계 기초자료 획득 및 신뢰성을 확인할 수 있었다.

• Land and Housing Review
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• v.2 no.3
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• pp.269-276
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• 2011

Recently, the chance of dew condensation in apartment buildings is increasing because of several reasons. For example, ventilation rate has been decreased because of high-insulations and airtightness for saving energy. Besides, the humidity has been made by drying washes, cooking and bathing inside of apartment buildings. However, there is lack of resonable design criteria for preventing condensation in real life and real surroundings. Therefore, this study is aimed at making a resonable design criteria of preventing condensation by measuring the indoor temperature and humidity in real life. In addition to this, it is aimed at making a resonable outdoor condition and classifying regions by using weather data. The following are the results. The interior criterion for condensation was set up $25^{\circ}C$ and a relative humidity of 55%. The outdoor criterion for condensation was set up $20^{\circ}C$, $-15^{\circ}C$, and $10^{\circ}C$ respectively for the hard frost, middle, and southern areas.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.566-568
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• 2005

STACIR/AW은 최근 사용이 증가되고 있는 증용량전선으로 기존 송전선에 비해 많은 전류를 송전하면서도 이도특성이 우수한 장점을 가지고 있다. 이 논문에서는 STACIR/AW 전선의 온도 및 대전류특성에 대한 실증시험을 위하여 구축된 송전선로용 3[kA]급 대전류 발생 장치를 이용해 345kV 송전선로의 표준경간인 350m 시험선로에 $480\;mm^2$ 및 $410\;mm^2$ 전선을 가선하여 전류 특성 시험을 수행하였다. 본 논문에서는 최대 허용전류에 대한 단계별 이도특성을 외기 조건과 전선의 장력 변화를 고려하여 고찰하여 국내 주요 전선사의 증용량전선에 대한 신뢰성을 검증하고, 또한 계절별 특성시험 및 환경시험 챔버를 이용한 참고시험과 기본적 동적해석을 통하여 외기 조건에 전선의 최대허용전류를 검토하였다. 또한 실선로에 적용된 $480\;mm^2$ 및 $410\;mm^2$ 의 증용량 전선에 최대 부하율을 파악하고 동일 조건에 부하전류를 인가한 실증시험을 통하여 전선의 이도증가율을 분석하여 상용선로의 운전조건을 검토하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.15-20
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• 2017

Currently, residential air conditioners operate as a heat pump during winter. In this case, the outdoor heat exchanger acts as an evaporator obtaining heat from cold air. On the other hand, it acts as a condenser during summer transferring heat to hot air. The outdoor temperature changes significantly from high to low. Generally, the air-side j and f factors are obtained at a standard outdoor temperature. Therefore, the applicability of the j and f factors under different outdoor conditions needs to be checked. In this study, tests were conducted for a two-row louver finned heat exchanger changing the outdoor temperature to subzero. The effects of the tube-side brine flow rate were also checked. The results showed that air-side j and f factors were essentially constant and independent of the outdoor temperature, suggesting that an extension of j and f factors obtained under standard conditions to a low outdoor temperature is acceptable. All j and f factors agreed within 9% and 3%, respectively. Tests were also conducted by changing the coolant flow rate. Both the j and f factors did not change according to the flow rate, suggesting that the tube-side heat transfer correlation is acceptable.

• Food Engineering Progress
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• v.13 no.4
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• pp.308-313
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• 2009

This study was conducted to design and fabricate a heat pump that can produce some weather conditions similar to those of the dry season of the rough rice in Korea, and to investigate basic performances of the apparatus. During the drying test, the amount of energy consumption and drying characteristics were measured at four different temperature levels ranging between 20$^{\circ}C$ and 50${^{\circ}C}$. In the psychrometric chart, the freezing capacity and refrigerant circulation ratio of the heat pump were 173 kJ/kg and 49.6 kg/hr, respectively. Therefore, coefficient of performance was 5.5, which was superior to that of refrigerant R-22 (4.0) in standard refrigeration cycle. In addition, the time to reach target drying temperature (30${^{\circ}C}$) and relative humidity (40%) were 6 minutes and 7 minutes, respectively. Temperature differences between the drying temperature and the rice were 1.5${^{\circ}C}$ and 8.5${^{\circ}C}$ at the drying temperatures of 21.9${^{\circ}C}$ and 48.7${^{\circ}C}$, respectively. This result demonstrated that the increased temperature of the rice in the drying section decreased sufficiently in the tempering section. At the drying temperatures of 21.9, 30.7 38.8, and 48.7${^{\circ}C}$, drying rates were 0.29, 0.61, 0.85, and 1.26%/hr, respectively, which were similar to those of commercial dryer. In addition, the amounts of energy consumption were 325, 667, 692, and 776 kJ/kg, respectively. These results showed that this dryer saved up to 86% of energy consumption compared with the commercial dryer, which uses 4,000-5,000 kJ/kg of fossil fuel.