• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.404-408
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• 2009

The liquid desiccant air-conditioning system has been proposed as an alternative to the conventional vapor compression cooling systems to control air humidity. The complete system of liquid desiccant air-conditioning system is consisted two main components those are humidifier (regeneration) and dehumidifier. Humidifier part is connected to the load when summer season which is the air condition is hot and humid have to be turned into comfort condition on human. This paper purpose is performances study of air flow rate effect on a structured packed tower on cooling and dehumidifier system using liquid lithium chloride as the desiccant. Experimental apparatus used in this present study is consisted of three components those are load chamber, packed tower and chiller. Load chamber’s volume is $40m^3$, and packed tower dimension is cubic with length 0.4m occupied with packed column. Totally, 15 experimental has done using 5 times repeat on each variable of air velocity that varying on 2m/s, 3m/s and 4m/s with other conditions are controlled. Air inlet initial temperature and relative humidity are set respectively on $30^{\circ}C$ and 52%, desiccant flow rate is 0.63 kg/s, desiccant temperature is $10^{\circ}C$ and desiccant concentration is 0.4. The result of this study shows that averagely, the moisture removal rate and the heat transfer rate are influenced by the air velocity. Higher air velocity will increase the heat transfer and decreasing the moisture removal rate. At adiabatic condition the air velocity of 2 m/s respectively is having the higher moisture removal rate acceleration then the air velocity of 3m/s and 4 m/s until the steady state condition.

• 설비공학논문집
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• 제12권11호
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• pp.994-1003
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• 2000

Control algorithms for the absorption air conditioning system may be developed by suing dynamic models of the system. The simplified effective dynamic models, which can predict the dynamic behaviors of the system, may help the development of effective control algorithms for the system. In this study, a dynamic simulation program for the absorption air conditioning system was developed. Dynamic models for an absorption chiller, a cooling tower, an air handling unit, a boiler, a three way valve, a controller, and a duct were developed and programed. Control algorithms for the absorption chiller, the cooling tower, and the air handling unit were selected, and analyzed to show the effectiveness of dynamic models. From the simulation results, it may be concluded that this simulation program may be effectively used for the development of optimal control algorithms of the absorption air conditioning system.

• 대한기계학회논문집 C: 기술과 교육
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• 제4권1호
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• pp.19-26
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• 2016

하이브리드 지열 히트펌프 시스템은 열원을 안정적으로 유지하기 위해 보조 히트싱크나 보조 열원을 활용한다. 본 연구에서는 병원 건물에 설치한 지열-냉각탑 하이브리드 시스템의 냉난방 성능을 분석하였다. 시스템에 각종 센서와 계측 장비를 설치하였으며, 2014년 2월부터 2015년 2월까지 측정한 데이터를 이용하여 성능을 분석하였다. 냉방 기간 중, 냉수 공급 온도는 평균 $11.7^{\circ}C$이었으며, 설계 온도인 $12^{\circ}C$를 넘지 않았다. 또한 난방 기간 중에는 일평균 $39^{\circ}C{\sim}40^{\circ}C$의 온수를 공급하였다. 지열 히트펌프만의 월 평균 성능지수는 3.8에서 8.4의 범위에서 변하였다. 반면 냉각탑을 포함한 하이브리드 지열시스템의 월 평균 성능지수는 2.6에서 6.6 사이에서 변하였다.

• Nuclear Engineering and Technology
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• 제52권4호
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• pp.734-741
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• 2020

A new air-cooled waste heat removal system with a direct contact heat exchanger was designed for SMRs requiring 200 MW of waste heat removal. Conventional air-cooled systems use fin structure causing high thermal resistance; therefore, a large cooling tower is required. The new design replaces the fin structure with a vertical string type direct contact heat exchanger which has the most effective performance among tested heat exchangers in a previous study. The design results showed that the new system requires a cooling tower 50% smaller than that of the conventional system. However, droplet formation on a falling film along a string caused by Rayleigh-Plateau instability decreases heat removal performance of the new system. Analysis of Rayleigh-Plateau instability considering drag force on the falling film surface was developed. The analysis results showed that the instability can be prevented by providing thick string. The instability is prevented when the string radius exceeds the capillary length of liquid by a factor of 0.257 under stagnant air and 0.260 under 5 m/s air velocity.

• 설비공학논문집
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• 제16권1호
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• pp.26-33
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• 2004

In general, an absorption chiller or heat pump is operated under the constant cooling water flow rate condition even though the system works with a partial load. The objective of this paper is to study the effect of the cooling water flow rates and the temperature of cooling water on the system performance to find the energy saving methode for the partial load operation of the double effect $H_2O$/LiBr absorption chiller. It is found that the performance of the system is sensitive to the temperature of cooling water than the cooling water flow rate, so the decrease of the performance due to reducing the cooling water flow rate can be overcome with the reduction of the cooling water temperature by 1$^{\circ}C$. The flow rate of the cooling water flow rate ranges from 50％ to 100％ of the flow rate at normal conditions with a partial load. It is also found that the operation cost of the cooling water pump and the cooling tower can be reduced by 23％.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.564-569
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• 2007

This study describes thermal performance of solar cooling and hot water for demonstration system with ETSC(Evacuated tubular solar collector) installed at Seo-gu art center of Kwangju. For demonstration study, a reading room with about 350㎡ was heated and cooled with the solar system. The system was consisted of ETSCs, storage tank, hot water supply tank, subsidiary boiler, subsidiary tank, absorption chiller, chiller storage tank, and cooling tower. The results of the experimental study indicated that the total solar energy gain as daily performance on a sunny day (August 25, 2007) with total daily radiation of $606\;W/m^2$ was 671 kWh, the collecting efficiency of 55%. In the case of supplies to heat source more than $83^{\circ}C$, cooling time operated by solar was driven 8.8 hours, cooling energy generated by solar system was 179 kWh and the solar cooling fraction was 79.2%, and hot water supplied with surplus heat source by the solar system was 201 kWh.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4335-4349
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• 2023

Nuclear marine propulsion has been emerging as a next generation carbon-free power source, for which proper passive residual heat removal systems (PRHRSs) are needed for long-term safety. In particular, the characteristics of unlimited operation time and compact design are crucial in maritime applications due to the difficulties of safety aids and limited space. Accordingly, a compact and long-term-operable PRHRS has been proposed with the key design concept of using both air cooling and seawater cooling in tandem. To confirm its feasibility, this study conducted system design and a transient analysis in an accident scenario. Design results indicate that seawater cooling can considerably reduce the overall system size, and thus the compact and long-term-operable PRHRS can be realized. Regarding the transient analysis, the Multi-dimensional Analysis of Reactor Safety (MARS-KS) code was used to analyze the system behavior under a station blackout condition. Results show that the proposed design can satisfy the design requirements with a sufficient margin: the coolant temperature reached the safe shutdown condition within 36 h, and the maximum cooling rate did not exceed 40 ℃/h. Lastly, it was assessed that both air cooling and seawater cooling are necessary for achieving long-term operation and compact design.

• Membrane and Water Treatment
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• 제8권4호
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• pp.355-367
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• 2017

In India, the current operation of condenser cooling system & effluent disposal system in existing power plants aims to reduce drawal of seawater and to achieve Zero Liquid Discharge to meet the demands of statutory requirements, water scarcity and ecological system. Particularly in the Steam-Electric power plants, condenser cooling system adopts Once through cooling (OTC) system which requires more drawal of seawater and effluent disposal system adopts sea outfall system which discharges hot water into sea. This paper presents an overview of closed-loop technology for condenser cooling system and to achieve Zero Liquid Discharge plant in Steam-Electric power plants making it lesser drawal of seawater and complete elimination of hot water discharges into sea. The closed-loop technology for condenser cooling system reduces the drawal of seawater by 92% and Zero Liquid Discharge plant eliminates the hot water discharges into sea by 100%. Further, the proposed modification generates revenue out of selling potable water and ZLD free flowing solids at INR 81,97,20,000 per annum (considering INR 60/Cu.m, 330 days/year and 90% availability) and INR 23,760 per annum (considering INR 100/Ton, 330 days/year and 90% availability) respectively. This proposed modification costs INR 870,00,00,000 with payback period of less than 11 years. The conventional technology can be replaced with this proposed technique in the existing and upcoming power plants.

• 한국지열·수열에너지학회논문집
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• 제3권1호
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• pp.23-29
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• 2007

For the perfomance test of geothermal system, a large pilot of capacity of 50RT is built and operated in office building. This system is planed hybrid system with cooling tower as asisstance heat sink. From October, 2004 to September, 2005, this system is operated andmonitored. As the result, COP of heating periods is about 3.46 and COP of cooling periods is about 4.1. Therefore, geothermal system is useful and suitable in Korea.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.179-184
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• 2011

The development of new energy has attracted consideration attention due to the high oil price and environmental problems. In advanced country, they have tried to carry out a long range plan for energy. We need to develop new energy for Low Carbon Green Growth in Korea. The building is 30% among ratio of energy consumption in Korea. And in the past, heating energy was high ratio for energy using at home. But recently, the demand for cooling energy keeps growing due to rising average temperature on the earth and improvement of life quality. In this situation, the energy of lake water and ocean water has studied to utilize in advanced country because of low temperature at underwater. But the study for deep water is still a lot left to do. In this study, we analyzed district cooling system and the present condition. Analyzing the deep lake water cooling system in Toronto, we found an application of district cooling system using deep ocean water. Deep lake water uses heat source for district cooling and water source for city in Toronto. So reducing the initial cost, this city had economic effect. When DLWC was applied at existing building, the heat exchanger was installed instead of cooling tower and refrigerator. And the heat exchanger used to connect main pipe with cool water on city. System using deep ocean water can be applied as a similar way to supply cool water from lake to building.