• Journal of Power System Engineering
• /
• v.9 no.4
• /
• pp.18-23
• /
• 2005

The experimental investigation was carried out to evaluate the performance of air-to-air heat exchanger with rotating porous plates newly developed in this study. The rotating porous plates are mounted with an equal interval of 18 mm inside the heat exchanger where the hot and cold airs enter at opposite ends. When flowing in opposite directions by the separating plate installed in the center of the rotating porous plates, the airs give and receive the heat each other. The material of the porous plate is cooper and its thickness is 1.0 mm. Air flow rate is varied from 10 to 120 m3/h. From the experiment of air-to-air heat exchanger with the rotating porous plates, the heat exchange performance increased with the increase in RPM of the porous rotating discs at the conditions of the same air flow rate. The sensible heat exchange efficiency was maximum 60 to 70 percent, and enthalpy exchange efficiency 50 to 60 percent.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.172.2-172.2
• /
• 2011

다양한 저급연료나 폐기물로부터 가스엔진이나 연료전지의 연료로 사용하기위한 연료가스를 얻기 위한 방법으로 가스화 기술을 적용할 수 있다. 폐기물의 가스화를 통해 발생된 합성가스에는 CO, $H_2$, $CO_2$와 같은 주요성분 이외에 황화합물($H_2S$, COS), 염소화합물(HCl), 고형 물질(분진)등의 오염물질이 포함되어 있으므로, 이용목적에 따라 적절한 정제 기술이 필요하게 된다. 현재 가장 널리 알려진 저온 습식 정제공정은 장치운전이 쉽고 오염물질 제거효율이 높은 장점이 있으나, 합성가스 온도를 상온까지 낮추기 때문에 현열 손실이 발생하는 단점을 가지고 있다. 고온 건식 정제공정에 의해 $300^{\circ}C$ 이상의 고온에서 오염물질의 제거가 가능하다면 에너지 이용효율을 높일 수 있고, 습식공정에 의해 발생되는 폐수처리에 따른 비용 절감효과도 얻을 수 있다. 폐기물 합성가스를 최종 적용처에 이용하기위한 고온 정제 공정의 적용을 위해 흡착제를 이용하여 탈황, 탈염 실험을 실시하였고, 실험결과로부터 장치 설계의 기초인자를 도출하였다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.2
• /
• pp.128-136
• /
• 2008

It is necessary to estimate the cooling load of the next day for effective control of ice thermal storage system. In this paper, new methodology is proposed to estimate the cooling load using design parameters of building and predicted weather data. Only six input parameters such as sensible heat coefficient and constant, latent heat coefficient and constant, maximum and minimum temperature are necessary to obtain hourly distribution of cooling load for the next day. Two benchmarking buildings(hospital and research institute) are selected to validate the performance of the proposed method, and the estimated cooling loads in hourly and daily bases are calculated and compared with the measured data for E hospital. The estimated results show fairly good agreement with the measured data for both buildings.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.24 no.2
• /
• pp.121-128
• /
• 2012

Improvement in the energy efficiency has been studied of the desiccant cooling system by applying a vapor compression type heat pump to modify the system into a hybrid system. The cycle simulation was performed and the results were compared between a reference desiccant cooling system composed of a desiccant rotor, a sensible rotor and a regenerative evaporative cooler, and a hybrid desiccant cooling system with the sensible rotor being replaced by a heat pump. Though the electric consumption increases as much as the compressor power consumption, the total cooling capacity increases and the thermal energy input decreases by the addition of the heat pump. Therefore, the total energy efficiency can be improved if the increase in the electric consumption can be compensated with the increase in the cooling capacity and the decrease in the thermal energy input. The results showed that the total energy efficiency is optimized at a certain heat pump capacity. When the heat from the CHP plant is used for the thermal energy input, the energy consumption of the hybrid system is reduced by 20~30% compared with the reference system when the heat pump shares 30~40% of the total cooling capacity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.6
• /
• pp.372-380
• /
• 2008

In order to control indoor air quality and save energy, it is needed to install a suitable ventilation system equipped with heat exchanger for heat recovery. Paper heat exchanger can recover $50{\sim}70%$ of the enthalpy difference between supply and exhaust air. The purpose of this research is to obtain the experimental correlations for the friction factor, heat transfer coefficient, mass transfer coefficient and permeance of paper heat exchanger, which can be used to predict the performance of the paper heat exchanger. Pressure drops at various velocities, and sensible and latent heat transfer rates at various dry-bulb temperatures, relative humidities and specific humidities are measured to derive experimental correlations. The results of prediction using correlations show fairly good agreement with the experimental data obtained in the actual operating conditions.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.103-103
• /
• 2023

질량 및 에너지 보존 법칙은 수문현상을 포함한 자연 현상의 기본 법칙이다. 유역에서 물의 질량 보존은 강수량 P가 유출량 Q, 증발산량 E, 그리고 육역저수량변화 ΔS로 분할되는 것(P=Q+E+ΔS)을 의미하며 열 에너지 보존은 순복사에너지 R_n이 잠열 λE, 현열 H, 그리고 지열 G로 분할되는 것(R_n=λE+H+G)을 의미한다. 유역에서 물과 에너지의 분배 과정은 E로 연결되어 있으며 이 두 과정을 포괄적으로 이해하는 것은 기후 및 지표환경의 변화를 예측하고 대비하는데 중요하다. 이 연구에서는 미국 전역의 400여개 유역에 대한 정보를 제공하는 Model Parameter Estimation Project(MOPEX) 데이터를 이용하여 유역의 기후 조건에 따라 물과 에너지의 분배가 어떻게 달라지는지 Budyko 평면에서 분석했다. 장기간에 대해 ΔS와 G는 무시할 수 있다는 가정하에 건조한 유역일수록 P, Q, 그리고 E 모두 작게 나타나는데 P와 Q의 감소폭이 훨씬 크기 때문에 E의 P에 대한 비는 크게 나타났다. 또한 건조한 유역일수록 E는 작고 R_n이 크기 때문에 H가 크게 나타났으며 H가 큰 유역일 수록 유역의 최대 기온과 최저 기온의 차이가 크게 나타났다. 이러한 변화는 동일한 유역내에서 물과 에너지 분배의 시간적 변화로도 나타나고 있다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.6
• /
• pp.483-491
• /
• 2014

In this study, a thermodynamic analysis was carried out for a combined power generation system using a low-temperature heat source in the form of sensitive energy and liquefied natural gas cold energy. An ammonia-water mixture, which is a zeotropic mixture, was used as the working fluid, and systems with and without a regenerator were comparatively analyzed. The effects of the mass fraction of ammonia and the condensation temperature of the working fluid on the system variables, including the net work production, exergy destruction, and thermal and exergy efficiencies, are analyzed and discussed. The results show that the performance characteristics of the system varied sensitively with the ammonia concentration or condensation temperature of the working fluid. The system without regeneration was found to be better in relation to the net work per unit mass of the source fluid, whereas the system with regeneration was better in relation to the thermal or exergy efficiency.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.11a
• /
• pp.130.1-130.1
• /
• 2010

미국과 유럽에서는 이미 10여 년 전부터 250MW급 이상의 대용량 석탄IGCC 플랜트를 상업운전 하고 있으며, 일본과 중국을 비롯한 아시아에서도 대용량 플랜트를 시운전하고 있거나 건설 중에 있다. 한국에서는 제4차 전력수급계획에 의거 태안화력 부지 내에 300MW급 IGCC 플랜트 건설을 추진 중이며, 두산중공업은 '10년 상반기에 IGCC 가스화 플랜트에 대한 FEED 설계 (Front-Eng Engineering Design)를 완료하였다. 그 과정 중 설계조건에 의한 기본 엔지니어링 사항과 석탄 가스화 플랜트에 대한 성능예측 결과를 본 연구에서 소개한다. 가스화 플랜트의 엔지니어링은 가스화 블록과 가스정제 블록으로 구분하여 수행하였다. Process Data를 이용하여 PFD Development, P&ID Generation, Equipment Specification 개발, HAZOP 수행, Architecture Engineering 등의 순으로 FEED 설계를 진행하였다. BOD (Basis of Design)를 기준으로 운전조건별 Heat & Mass Balance와 Process Flow를 재검토하고 각 기기별 운전개념을 반영하여 P&ID를 개발하였다. 그리고 배관, 전기 및 제어에 대한 각종 Diagram 개발과 HSE (Health, Safety and Environment) 관련 설계를 수행하였다. IGCC 1호기의 엔지니어링 수행과 함께 Next 호기 자체설계 역량 확보를 위해 두산중공업은 'DIGITs'로 명명된 개념기본설계 Tool을 개발하고 있다. DIGITs는 공정모델링, 단위기기 개념설계, 공정구성 (Process Configuration) 및 종합 Database Package 형태로 구성된다. DIGITs에 의한 계산 결과 공정사 Process Data 기준시 가스화 블록 출구에서 Syngas HHV와 Syngas 현열은 각각 약 $636MW_{th}$와 약 $18MW_{th}$로, Plant 설계조건 $630MW_{th}$를 만족하는 것으로 예측되었다. 향후 DIGITs는 가스정제 블록 및 주변 BOP 설비 등과 연계한 종합 개념기본설계 Tool로써 개발 진행 중이다.

• Journal of the Korean earth science society
• /
• v.25 no.2
• /
• pp.94-108
• /
• 2004

In order to clarify the efficiency of ground level change in Ice-valley on atmospheric circulation, numerical experiment was carried out. The circulations over the slope in North and South are different due to the topography and short wave radiation in Ice-valley. Therefore the circulations in both side are asymmetric and the asymmetric circulations are kept on at 1800 LST. A small difference of the atmospheric circulations formation is made due to the road construction at night. The reason may be the weakness of sensible heat flux from the road and other factors except that the sensible heat is not a principal factor in road construction. The construction of road is associated with growing of sensible heat from the road surface. For this reason, in case of daytime, ascending wind in north slope is more stronger with the road than that without road. The maximum wind speed becomes 4.67 m/s after road construction. And the position of the road is also an important factor in estimation of mesoscale circulation in mountainous area.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.7
• /
• pp.571-579
• /
• 2014

A series of field tests on hybrid desiccant cooling systems were conducted in July-August, 2013. The temperature and humidity of the supply and return air, power, and heat consumption were monitored and transferred in real time through the Internet. The performance parameters of the cooling system, namely, cooling capacity and COP (coefficient of performance), were evaluated from the measured data and their variations under outdoor conditions was analyzed. It was found that with increase in the outdoor temperature, the total energy decreases and cooling capacity increases whereas the latter decreases with increase in the outdoor humidity. The COP was also found to increase with the increase in outdoor temperature.