• 수산해양기술연구
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• 제35권2호
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• pp.196-200
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• 1999

In the case that erosion and corrosion occurs in machinery and structure at the same time, the synergy effect by erosion-corrosion affects fatal effect to durability of machinery and structure. Therefore, in machinery and structure which use corrosion liquid, the study of the synergy effect of erosion-corrosion which affects metal material is requested. In this paper. the flow corrosion experiment about the effect of temperature change and liquid velocity change in sea water was carried out to study the characteristics of erosion-corrosion for tube material Cu heat exchanger The main results obtained are as follows. (1) Damage appearance of tube outside by erosion-corrosion becomes dull because electrode potentials of Cu tube is higher than electrode potential of STPG38 shell. (2) In the cooling system by sea water, the weight loss rate of Cu at tube outside liquid temperature of $70^{\circ}C$ is higher than that of temperature of $20^{\circ}C$. (3) In cooling system by sea water, the weight loss rate of Cu at liquid velocity of 5.1m/s is higher than that of velocity of 1.47m/s. But as the testing time passed, the weight loss rate of Cu at velocity of 5.1m/s is almost steady and becomes dull at velocity of 1.47m/s.

• 한국압력기기공학회 논문집
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• 제18권2호
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• pp.69-76
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• 2022

In order to prepare for a future nuclear market, research for developing floating small modular reactor has been initiated with the aim of differentiating it from large nuclear power plants such as distributed power, heat supply to remote communities and sea water desalination. Depending on the characteristics of the small modular reactor, it is necessary to design a plate and shell heat exchanger that can be manufactured smaller than the U-tube recirculation method. In this study, 12 cases are selected by changing the diameter of the heat plate, the thickness of the device body and the size of the stiffener. Finite element analysis is performed by setting the stress classification lines for the point at which deformation is expected under external pressure conditions for these analysis cases. For the basic design of the plate and shell heat exchanger, the optimal conditions are derived by analyzing the tendency of stress change in the device body and stiffener.

• Journal of Advanced Marine Engineering and Technology
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• 제26권1호
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• pp.99-107
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• 2002

Recently all kinds of structural materials are subjected to the severe corrosive environment. Especially corrosion problems of heat exchanger such as galvanic corrosion, erosion and cavitation raised by both contaminated solution and high velocity of fluid to increase cooling effect of heat exchanger have been frequently reported in these days. In this study two kinds of sheet materials and five kinds of tube materials are used for galvanic corrosion characteristics and their corrosion current density calculation. The tube materials having the most galvanic corrosion resistance between tube and sheet of heat exchanger were Al Brass(68700) and Al Brass(C6872TS) and although Ti tube predominantly indicated the highest individual corrosion resistance among those five tube materials. it appeared that Ti tube can be allowed as sheet materials to get galvanic corrosion easily. However it is considered that Cu-Ni tube materials is not only easy to produce galvanic corrosion significantly between tube and sheet regardless of kinds of sheet materials but also is appeared considerably its own high corrosion current density

• 해양환경안전학회지
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• 제24권7호
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• pp.916-922
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• 2018

는 열교 환기를 세척할 때 최근 신재생에너지의무화제도(RPS: Renewable Portfolio Standard)대상 신재생에너지 항목에 발전소 온배수가 신재생에너지공급인증서(REC:Renewable Energy Certificate)의 수열에너지(가중치 1.5)로 추가되어 온배수 열원에 대한 가치가 높아졌다. 본 연구에서는 고탁도지역 온배수의 직접적인 활용을 위한 방안으로 히트펌프시스템 내 탁도저감장치를 도입하여 열교환기에 가해지는 오염물질의 저감 효과를 확인해보기 위해 한 달 동안 실증테스트를 실시하였다. 실험결과 탁도 저감효과가 80 % 이상으로 고탁도 지역의 온배수 활용을 위한 방안으로 탁도저감장치의 적용가능성을 확인 할 수 있었다. 또한 탁도저감시스템에 따른 열교환기의 오염도 저감 효과를 검증하기 위해 30일간 운전한 열교환기를 해체하여 분석해본 결과 탁도저감시스템을 거친 열교환기보다 그렇지 않은 열교환기의 오염정도가 높은 것을 확인하였다. 열교환기에 유입된 오염물질(스케일)을 분석해본 결과 주로 $SiO_2$, $Na(Si_3Al)O_8$, $CaCO_3$, NaCl 성분의 광물이 검출되었는데 이는 높은 탁도로 인해 해양퇴적토가 열교환기에 유입된 것으로 분석되었다. 그 외에도 소량이지만 $TiO_2$, MnO, $Cr_2O_3$가 검출되었다. 이는 열교환기를 세척할 때 열교환기 재료로부터 기인한 중금속이 소량 용출된 것으로 판단된다.

• 한국태양에너지학회 논문집
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• 제27권4호
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• pp.35-41
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• 2007

To demonstrate the desalination system, the demo-plant was scheduled to be installed. The system was planned to use solar thermal collector as heat source and PV as electricity source. For the design of the desalination demonstration system, firstly the solar thermal system would be well designed from the result between the supplied heat into the fresh water generator and the fresh water yield. The generator for demonstration system was chosen as the fresh water generator of the single stage and effect with plate-type heat exchanger using low pressure evaporation method. The test facility for the tests to reveal the relationship between the fresh water yield and the supplied heat flow rate was designed and manufactured. The maximum fresh water yield of two fresh water generators applied in this study was designed as 1.5 Ton/day. The parameters relating with the performance of fresh water generator are known as sea water inlet temperature, hot water inlet temperature, and hot water flow rate. Through the experiments, this study firstly showed detail operation characteristics of the generator and designed the solar thermal system for the demonstration system.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1279-1284
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• 2008

The alternative energy has lately attracted considerable attention due to the high oil price and environment problem. Deep sea water that is one of the natural energy sources should be getting popular continually to reduce the environment problem. In this study, cooling system of deep sea water using heat exchangers of two hotels where is located in near Hae-undae Bay has been analyzed on the quantity of electricity comparison between existing cooling system and deep seawater cooling system. As shortly, the results of study showed that the first building approximately saves 370 millions won per year, also the second building saves 248 millions won per year. It means that the cooling system by using deep sea water has great worth to reduce the ratio of fossil fuel.

• Corrosion Science and Technology
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• 제9권5호
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• pp.187-195
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• 2010

Hyper duplex stainless steels have been developed in Korea for the purpose of application to the seawater system of Korean nuclear power plants. This system supplies seawater to cooling water heat exchanger tubes, related pipes and chlorine injection system. In normal operation, seawater is supplied to heat exchanger through the exit of circulating water pump headers, and the heat exchanged sea water is extracted to the discharge pipes in circulating water system connected to the circulating water discharge lines. The high flow velocity of some part of seawater system in nuclear power plants accelerates damages of components. Therefore, high strength and high corrosion resistant steels need to be applied for this environment. Hyper duplex stainless steel (27Cr-7.0Ni-2.5Mo-3.2W-0.35N) has been newly developed in Korea and is being improved for applying to nuclear power plants. In this study, the physical & mechanical properties and corrosion resistance of newly developed materials are quantitatively evaluated in comparative to commercial stainless steels in other countries. The properties of weld & HAZ (heat affected zone) are analyzed and the best compositions are suggested. The optimum conditions in welding process are derived for ensuring the volume fraction of ferrite(${\alpha}$) and austenite(${\gamma}$) in HAZ and controlling weld cracks. For applying these materials to the seawater heat exchanger, CCT and CPT in weldments are measured. As a result of all experiments, it was found that the newly developed hyper duplex stainless steel WREMBA has higher corrosion resistance and mechanical properties than those of super austenitic stainless steels including welded area. It is expected to be a promising material for seawater systems of Korean nuclear power plants.

• Journal of Advanced Marine Engineering and Technology
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• 제41권3호
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• pp.197-201
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• 2017

대부분의 어선에서는 포획된 어류를 관리하고 저장하기 위해 얼음 냉각 시스템을 사용한다. 그러나 얼음 냉각 시스템은 작동 시간의 제한뿐만 아니라 적절한 온도와 염분 농도를 유지하는 것이 어려운 단점이 있다. 본 연구의 목적은 어류 운반선의 어창에 적정한 해수온도 유지를 위한 해수 냉각 시스템용 만액식 증발 열전달 특성을 파악하는데 있다. 실험은 냉매의 해수 온도, 유량 및 포화 온도의 변화를 주며 열전달 특성을 파악하였다. 동일 열유속에서 Aluminium-Brass tube가 Copper-Nickel tube 보다 외측 열전달계수가 약 10% 큰 것으로 확인할 수 있었으며, 이를 통해 해수용 열교환기의 전열관으로 Aluminium-Brass를 적용하는 것이 열전달 측면에서 효과적일 것을 확인할 수 있었다. 만액식 단관 열전달계수와 18 kW급 만액식 해수냉각시스템의 총괄열전달계수의 비교를 통해 동일 조건에서는 25%정도 단관의 열전달계수가 큰 값을 나타내었으며, 이러한 결과는 만액식 관군 열교환기의 설계를 위한 중요한 자료가 되리라 판단된다.

• Journal of Welding and Joining
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• 제28권1호
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• pp.66-71
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• 2010

With large specific strength and outstanding corrosion resistance and erosion resistance in sea water, titanium and titanium alloy are widely used in heat exchanger production. In particular, pure titanium demonstrates outstanding molding performance and may be considered optimal for production of heat exchanger. Since titanium is very vulnerable to oxidation and embrittlement during welding, processes with less heat input are widely used, and laser welding is widely applied by considering production performance and shield etc in atmosphere. So far, 1st report and 2nd report compared and analyzed embrittlement degrees by bead colors of weldment through oxygen and nitrogen quantitative analysis and hardness measurement, and evaluated welding performance and mechanical properties of butt welding. This study evaluated field applicability of lap welding to heat exchange plate of LPG re-liquefaction device for ships through tensile stress test, hardness test and internal pressure test etc after deducing optimal weding condition and applying to actual heat exchange plate. In bead overlap area, the experiment produced sound welds with no porosity or defect by increasing and decreasing laser power, and tensile-shear test results indicated virtually the same tension and yield strength as base metal. As a result of measuring hardness at lateral cross section and bead overlap zone of actual heat exchanger welds, hardness difference within 20Hv was produced at base metal, HAZ and weldment, and as a result of pneumatic and hydraulic pressure test, no leakage occurred.

• 한국기계가공학회지
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• 제12권6호
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• pp.125-131
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• 2013

This study was carried out to develop a diesel engine for marine propulsion. This marine diesel engine was developed based on a 500Ps vehicle diesel engine. Many main parts, such as the intercooler, radiator, and engine controller were designed for the marine diesel engine. The intercooler was designed to be of sea water cooling type; inlet air is cooled by sea water. Engine coolant is cooled by sea water in the radiator too. The water cooling heat exchanger has high cooling performance. In the cooling system, consists of the intercooler and the radiator, the sea water passes through the intercooler and then the radiator, in sequence. This process is very effective compared to the reverse method in which sea water passes through the radiator and then the intercooler, in sequence. The control performance of the engine controller and the fuel injection rate were improved using an engine speed controller. This system was tested on an engine dynamometer and an exhaust gas analyzer using the marine diesel engine test method. Test results show that the 500Ps marine diesel engine satisfied the IMO NOx regulations; Tier II.