• 한국전산유체공학회지
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• 제17권4호
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• pp.1-8
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• 2012

During a reactor normal operation, two parallel 50% capacity cooling pumps circulate primary coolant to remove the fission reaction heat of the reactor through heat exchangers cold by a cooling tower. When one pump is failure, the other pump shall continuously circulate the coolant to remove the residual heat generated by the fuels loaded in the reactor after reactor shutdown. It is necessary to estimate how much flow rate will be supplied to remove the residual heat. We carried out a flow network analysis for the parallel primary pumps based on the piping network of the primary cooling system in HANARO. As result, it is estimated that the flow rate of one pump increased about 1.33 times the rated flow of one pump and was maintained within the limit of the cavitation critical flow.

• 대한기계학회논문집B
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• 제32권5호
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• pp.335-341
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• 2008

Thermal transport from vertical heated surface to falling liquid film in a channel has been investigated experimentally. Air-flow is introduced into channel to make a counter flow against falling liquid film. This problem is of particular interest in the design of direct contact heat exchange system, such as cooling tower, evaporative cooling system, absorption cooling system, and distillation system. The effects of channel width and air flow rate on the heat transfer to falling liquid film are studied in detail. The results obtained indicate that heat transfer rate is gradually decreased with an increase in the channel width without air flow as well as with air flow in a channel. It is also found that heat transfer rate of air-flow is increased while heat transfer rate of falling liquid film is decreased with an increase in the air flow rate at a given channel width. However, total heat transfer rate from the heated surface is increased as the air flow rate is increased.

• Journal of Advanced Marine Engineering and Technology
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• 제40권4호
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• pp.282-287
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• 2016

최근 조선사들은 선박이 운항되는 연안 환경의 개선과 보호를 위하여 $CO_2$를 절감할 수 있는 친환경 선박과 함께 선박 운항 중 소비하는 에너지의 절감을 위한 고효율화 선박 개발의 노력도 활발하게 수행하고 있다. 본 연구에서는 전기로 구동되는 선박의 증기압축식 냉동기 대신에 선박 엔진 자켓수의 폐열을 이용하여 냉방을 할 수 있는 흡수식 냉동기의 적용 가능성과 냉각시스템에 냉매를 적용하는 시스템의 성능을 분석하였다. 연구결과, 해수와 열교환하여 액화될 수 있는 냉매들 중 R236fa가 가장 적합한 냉매로 분석되었으며, 이를 적용한 흡수식 냉동기의 COP는 0.798로 육상의 냉각탑을 이용한 수랭식보다 15% 그리고 해수 열교환기식 수랭식보다 5% 향상되었다. 냉동능력 1RT를 얻기 위한 LiBr 흡수용액 순환량은 0.013 kg/s로 수랭식 보다 25% 이상 감소하며, 냉각 매체 순환량도 수랭식의 15.7%에 불과한 매우 효과적인 냉동기가 되었다. 해수온도가 $18^{\circ}C$ 이하로 낮으면 발생하게 되는 LiBr의 결정화는 재생기에서 배출되는 엔진 자켓수의 온도를 이용하여 해수 온도를 상승시킴으로써 방지할 수 있다.

• 한국산학기술학회논문지
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• 제14권12호
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• pp.6072-6081
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• 2013

본 연구에서는 냉각탑 출구의 상대습도를 낮춰 백연을 저감하기 위한 목적으로 쉐브론형, 웨이브형 그리고 딤플형 공기가열기 시료에 대한 성능시험을 수행하였다. 실험은 시료의 전방풍속 1~3 m/s, 물 유량 0.19~0.33 kg/s 범위에서 수행되었다. 실험 결과 모든 시료에서 전열량은 전방풍속과 물 유량이 증가할수록 증가하였다. 공기측 압력손실도 풍속이 증가할수록 증가하였다. 동일 풍속에서 전열량은 쉐브론 형상에서 가장 크고 (평판의 1.5~1.7배) 딤플, 웨이브, 평판 순으로 나타났다. 소비동력 대비 전열량도 쉐브론 형상에서 딤플 형상보다 15% 정도 크게 나타났다. 하지만 다른 세 종류의 형상에서는 큰 차이를 보이지 않았다.

• 한국산업융합학회 논문집
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• 제25권3호
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• pp.379-386
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• 2022

The goal of this research is to verify a performance test system for a low speed, high torque, and harsh reducer at low cost. The reducer rotates a cooling fan with a diameter of 10 meters, in a high temperature (50℃) cooling tower in a geothermal power plant. It requires about 500 kgf·m torque and 47.75 kW power to rotate the fan at a maximum power condition. An expensive dynamometer is commonly used for performance test of a motor or a reducer. In this paper, a low cost system is developed using a hydraulic pump as a load unit to generate torque instead of a dynamometer. We accurately calculated the required power, the flow meter, and the pressure of the pump, and selected to design and optimize the system at minimal cost. The system also applied another reverse reducer and a gearbox to increase the rotational speed and to reduce the torque from the low speed and high torque target reducer. This allows low-cost systems to be built using inexpensive components. The developed system was able to successfully measure the high torque and the low rotational speed of the target reducer at high temperature.

• Advances in environmental research
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• 제4권3호
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• pp.155-172
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• 2015

In this study, a complete set of recirculating cooling water system and the required instruments were built in a semi-industrial-scale and a 50 g/h ozone generation plant and a chlorine system were designed for cooling water treatment. Both chlorination and ozonation treatment methods were studied and the results were analyzed during two 45-days periods. The concentrations of ozone and chlorine in recirculating water were constant at 0.1 mg/lit and 0.6 mg/lit, respectively. In ozone treatment, by increasing the concentration cycle to 33%, the total water consumption decreased by 26% while 11.5% higher energy efficiency achieved thanks to a better elimination of bio-films. In case of Carbon Steel, the corrosion rate reached to 0.012 mm/yr and 0.025 mm/yr for the ozonation and chlorination processes, respectively. Furthermore, consumptions of the anti-corrosion and anti-sedimentation materials in the ozone cooling water treatment were reduced about 60% without using any oxidant and non-oxidant biocides. No significant changes in sediment load were seen in ozonation compared to chlorination. The Chemical Oxygen Demand of the blow-down in ozonation method decreased to one-sixth of that in the chlorination method. Moreover, the soluble iron and water turbidity in the ozonation method were reduced by 97.5% and 70%, respectively. Although no anaerobic bacteria were seen in the cooling water at the proper concentration range of ozone and chlorine, the aerobic bacteria in chlorine and ozone treatment methods were 900 and 200 CFU/ml, respectively. The results showed that the payback time for the ozone treatment is about 2.6 years.

• 설비공학논문집
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• 제12권12호
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• pp.1098-1125
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• 2000

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 1998 and 1999 has been done. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environment. The conclusions are as follows. 1) A review of the recent studies on fluid flow, turbomachinery and pipe-network shows that many experimental investigations are conducted in applications of impingement jets. Researches on turbulent flows, pipe flows, pipe-networks are focused on analyses of practical systems and prediction of system performance. The results of noise reduction in the turbomachinery are also reported. 2) A review of the recent studies on heat transfer analysis and heat exchanger shows that there were many papers on the channel flow with the application to the design of heat exchanger in the heat transfer analysis. Various experimental and numerical papers on heat exchanger were also published, however, there were few papers available for the analysis of whole system including heat exchanger. 3) A review of the recent studies on heat pump system have focused on the multi-type system and the heat pump cycle to utilize treated sewage as the heat source. The defrosting and the frosting behaviors in the fin-tube heat exchanger is experimentally examined by several authors. Several papers on the ice storage cooling system are presented to show the dynamic simulation program and optimal operation conditions. The study on the micro heat pipes for the cooling of high power electronic components is carried out to examine the characteristics of heat and mass transfer processed. In addition to these, new type of separate thermosyphon is studied experimentally. 4) The recent studies on refrigeration/air conditioning system have focused on the system performance and efficiency for new alternative refrigerants. New systems operating with natural refrigerants are drawing lots of attention. In addition to these, evaporation and condensation heat transfer characteristics of traditional and new refrigerants are investigated for plain tubes and also for microfin tubes. Capillary tubes and orifice are main topics of research as expansion devices and studies on thermophysical properties of new refrigerants and refrigerant/oil mixtures are widely carried out. 5) A review of the recent studies on absorption cooling system shows that numerous experimental and analytical studies on the improvement of absorber performance have been presented. Dynamic analysis of compressor have been performed to understand its vibration characteristics. However research works on tow-phase flow and heat transfer, which could be encountered in the refrigeration system and various phase-change heat exchanger, were seemed to be insufficient. 6) A review of recent studies on duct system shows that the methods for circuit analysis, and flow balancing have been presented. Researches on ventilation are focused on the measurement of ventilation efficiency, and variation of ventilation efficiency with ventilation methods by numerous experimental and numerical studies. Furthermore, many studies have been conducted in real building in order to estimate indoor thermal environments. Many research works to get some information for cooling tower design have been performed but are insufficient. 7) A review on the recent studies on architectural thermal environment and building mechanical systems design shows that thermal comfort analysis is sitting environment, thermal performance analysis of Korean traditional building structures., and evaluation of building environmental load have been performed. However research works to improve the performance of mechanical system design and construction technology were seemed to be insufficient.

• 설비공학논문집
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• 제16권9호
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• pp.881-888
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• 2004

Control algorithms for a dual source chiller air conditioning system were developed. These are control algorithms for the supply air temperature control, the supply header chilled water temperature control, the chiller chilled water temperature control, and the cooling tower water temperature control. These algorithms were analyzed by using a dynamic simulation program. Simulation results showed the energy savings and the satisfactory controls of an absorption and centrifugal chiller air conditioning system. Therefore, control algorithms developed for this study may effectively be used for the improved controls of the dual source chiller air conditioning system.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2004년도 하계학술발표 논문집
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• pp.174-174
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• 2004

• 공업화학
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• 제20권4호
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• pp.391-395
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• 2009

폐목재의 에너지 전환을 위하여 2톤/일 규모의 고정층 가스화기($0.9m{\times}2.4m$)를 제작하여 실험하였다. 고정층 가스화 설비는 3~5 cm의 목재칩을 이용하였으며 하부에는 회전식 스토커가 설치되어있다. 목재칩 연료 투입은 다단 나이프밸브 방식으로 되어 있으며 관성력 집진설비, 가스냉각용 열교환기, ID Fan 및 Cooling tower 등으로 구성되어져 있다. 가스화기는 $700{\sim}1000^{\circ}C$ 사이에서 조업하였으며 CO: 25~40 vol%, $H_2$: 7~12 vol%, $CH_4$: 2~4 vol%, $CO_2$: 12~24 vol%의 조성을 가지는 합성가스가 생성되었다. 합성가스 발열량은 $1100{\sim}1500kcal/Nm^3$으로 나타나 공업로의 적용이 가능하였다. 또한 합성가스의 가스 엔진을 통한 전력 생산도 가능하여 1~4 kW의 전력을 생산하였다.