• 한국태양에너지학회 논문집
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• 제34권3호
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• pp.115-121
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• 2014

With increment on interesting about improving renewable energy efficiency, many research have been conducted and the research about hybrid air-water heater using solar energy that can make heating air and hot water has been conducted also. In this experiment, the temperature difference and thermal efficiency were investigated when two heating medium(air and liquid) was working simultaneously. As a result, thermal efficiency showed 44% to 88% when these heating medium was working simultaneously depending on operation condition and it is better than traditional solar collector. Also possibility of application into building equipment also was confirmed based on temperature and thermal efficiency. But necessity of additional studies about proper operation condition according to purpose of use and heat load was confirmed because change of thermal efficiency by air velocity and flux of liquid was shown a huge difference.

• 설비공학논문집
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• 제26권5호
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• pp.224-230
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• 2014

The purpose of this paper is to investigate the performance of supplemental cooling and heating system equipped with the 1 kW thermoelectric module. The system consist of 96 thermoelectric modules, heat sink with louver fin and water cooling jacket which is attached on the hot side of the thermoelectric module. The cooling and heating performance test of the thermoelectric system is conducted with various conditions, such as intake voltage, air inlet temperature, air flow volume, water inlet temperature and water flow rate at calorimeter chamber in consideration of environmental conditions in realistic vehicle drive. The experimental results of a thermoelectric system shows that the cooling capacity and COP is 1.03 kW, and 1.0, and heating capacity and COP is 1.53 kW, and 1.5 respectively.

• 에너지공학
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• 제25권3호
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• pp.130-135
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• 2016

본 연구에서는 비정질 강섬유 혼입 바닥몰탈을 이용한 바닥난방시스템과 일반 몰탈을 사용한 바닥난방시스템의 열성능을 비교 평가하기 위하여 시뮬레이션을 실시하였다. 시뮬레이션은 온수공급온도를 변화시켰으며 다음과 같은 결론을 얻었다. 바닥의 표면온도, 실내의 공기온도 등을 검토 결과 강섬유온돌을 사용할 경우에는 실내공기를 기준으로 하면 강섬유온돌이 일반온돌에 비해 7~9%에 가까운 열효율이 상승되었으며, 바닥의 온도를 기준으로 하면 2~4% 온도상승이 일어나는 것으로 나타났다.

• 설비공학논문집
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• 제5권4호
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• pp.295-305
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• 1993

Thermal performance of test cell of model hot water Ondol house was simulated by equivalence heat resistence and heat capacity method. In this method wall was replaced by two equivalence and one heat capacity. This method enables to simulate the variation of temperature of each element of model house. The effect of pipe diameter, pitch of pipe and with or without consideration of inter-radiation between wall surfaces on the energy consumption rate were investgated. Results show that radiations between the ground surface of room and wall surfaces contribute to the heating of room air by reducing the convection heat loss through the wall surfaces.

• International Journal of Air-Conditioning and Refrigeration
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• 제15권3호
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• pp.108-113
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• 2007

The performance of a solar water heater incorporating evacuated tubes was evaluated using a transient simulation program, TRNSYS. Simulations were performed for $60^{\circ}C$ of hot water load temperature and for 280 liter of daily hot water volumes and three 400 liter of storage tank volumes. Three patterns of daily hot water consumption profile were used in the present study (morning, lunch and evening). The results show that the increase in solar fraction depends on the load profile, as well as the collector efficiency coefficient. Hot water draw profile has a large effect on the performance of the SDHWS, the morning load profile has the highest solar fraction. The annual solar fraction of the system, at the weather conditions of Jinju is approximately 84% at lunch load pattern, the 280 kg of load volume, 400 kg of tank volume and the $60^{\circ}C$ of load temperature.

• 설비공학논문집
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• 제8권2호
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• pp.187-197
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• 1996

A computer program for thermal design analysis has been developed to predict the operating characteristics and performance of an absorption heat pump to recover $30{\sim}40^{\circ}C$ of waste hot water. The effects of heat transfer area of the system components, temperature and mass flow rate of heat transfer medium, and solution circulation rate on the system performance are investigated in detail. The results obtained indicate that the COP is increased with a decrease in the temperature of driving steam and with an increase in the temperature of waste hot water while the COP is little affected by the variation of a hot water temperature. It is also found that the heating output is increased with an increase in the temperature of waste hot water and driving steam as well as with a decrease in the temperature of hot water. The simulation results are also compared with the experimental results for a periodic operation of the system and obtained a satisfactory agreement.

• 설비공학논문집
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• 제23권11호
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• pp.762-768
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• 2011

We use floor radiant heating system in the house of commons in winter Floor radiant heating system, which transfer heat by radiation, is one of the energy efficient and comfortable systems that. Floor radiant heating system is configured to be controlled by the room for energy-saving. Proper flow rate to a comfortable heating in the room is important. However, Using a constant speed circulation pump in separate rooms, heating system may cause an imbalance because of the difference of length of coil when operating in the rooms. In this study, our Research team examined heating imbalance due to the variation length through the coil length changes and flow control of the circulation pump.

• 설비공학논문집
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• 제3권4호
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• pp.276-285
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• 1991

The transient heat transfer characteristics in the radiant heating panel were predicted by numerical analysis. Thermal behaviors of panel, such as temperature distributions in panel and convective and radiative heat fluxes in panel surface with respect to time were obtained. Heating hours per day, rate of energy supplied and maximum temperature differences at panel surface were also compared for several important parameters. The performance and thermal comfort of heating panel were studied and compared for various operating and design conditions such as pipe pitch, pipe location, pipe diameter and flow rate of hot water for the purpose of producing useful data, which can be used for the test and decision of efficient operating condition of the conventional heating systems or the optimal design of the new panel heating systems.

• 설비공학논문집
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• 제19권8호
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• pp.577-584
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• 2007

A variable-flow-rate balancing valve has been developed and optimized to apply to a distributor in a hot-water heating system. Fluid dynamic performance of the system was evaluated by comparing the results with the previous pressure difference control valve (PDCV) system. In view of the variations of pressure drop and flow rate according to the sequential closing of the control valves, the present system which is named "smart system distributor", is very stable without a certain flow rate concentration. The level of pressure drop variation is also low as compared with the previous system with a PDCV. In view of the occurrence of cavitation, the present system is quite superior to the previous system because the instantaneous pressures at all sections are much higher than the vapor pressure. On the other hand, the previous system has a possibility of cavitation when one or more control valves are closed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.489-496
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• 2004

전동차 출입문에 에어 커튼을 설치시 객실의 냉난방 효과에는 외부의 찬공기나 더운 공기를 차단하고 외부로부터의 먼지, 배기가스, 냄새, 연기 등의 침입을 방지함으로 위생에 좋으며 항상 쾌적하고 깨끗한 실내를 유지하며, 객실내의 온도 분포가 균일함으로써 건강에도 도움이 된다 냉방시의 냉기 난방시의 온기, 손실을 줄여 냉. 난방 유지비를 대폭 절감 할 수 있으며, (약 86$\%$) 설치 전보다 승객의 출입에 쾌적함을 주며 경영주에게는 경비 절감을 위한 필수품이 되며 예산 절감에 효과가 있다. 출입문 부근의 승객에게도 출입문의 개폐시 냉온의 온도 변동이 없어 승객에게 쾌적감을 느끼게 하며, 객실 온도는 출입문을 열거나 닫을 때 온도 차이가 있다. 연구의 주목적은 외풍 문제에 관계없는 만족스러운 열환경 상태를 유지하는데 있으며 전동차 출입문에 에어 커튼을 설치했을 때 온도의 변화 도를 연구하였다. 그리고 온도는 객실 바닥에서 0.1 0.5 1.3 1.7m 높이에서 측정하였으며 온도 병화의 원인은 외풍에 더 많은 영향을 받는다는 것을 발견하였다.