• Journal of Advanced Marine Engineering and Technology
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• 제36권8호
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• pp.1050-1060
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• 2012

SOFC시스템 고효율화의 한 방법으로 SOFC/GT 하이브리드시스템은 유효하다. 그러나 시스템의 출력 규모가 수십 MW급의 선박용이라면 하부시스템으로 사용되는 GT시스템의 냉각방식 도입은 장치를 복잡하게 만들고 제어 또한 쉽지 않게 된다. 따라서 선박용으로는 SOFC/GT(유냉각) 하이브리드시스템보다 SOFC/GT(무냉각) 하이브리드시스템이 더 적합해 보인다. 본 연구는 SOFC/GT(무냉각) 하이브리드시스템을 구축하고 그 시스템에 대한 스택의 작동온도와 전류밀도, 가스터빈의 압력비, TIT가 시스템의 성능에 미치는 영향 등을 시뮬레이션을 통하여 검토한 것으로 공기압축기 소요 동력의 증가에도 불구하고 전기적 효율은 상승되며 TIT에는 운전을 위한 제한된 온도범위가 존재한다는 것을 알 수 있었다.

• 해양환경안전학회지
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• 제27권6호
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• pp.839-845
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• 2021

본 연구에서는 CO₂ 가스 배출 저감 및 선박 폐열 회수 증대를 목적으로 선박 배기로 버려지는 폐열을 전기로 변환하는 ORC(Organic Rankine Cycle) 발전에 대해 시뮬레이션을 통한 냉매별 효율을 보여주고 있다. 상대적으로 고온인 배기가스의 폐열과 상대적으로 저온인 냉각해수를 이용하여 Aspen HYSYS 11을 이용하여 시뮬레이션을 수행하였다. 해수냉각 ORC 발전시스템의 시뮬레이션 결과, 작동유체 효율은 R717 냉매가 2.86 %로 가장 높았고, 다음 순으로 R152a, R134a, R143a, R125a로 나타났다.

• 해양환경안전학회지
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• 제20권3호
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• pp.304-311
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• 2014

In this study, to apply hydrogen energy to ship engine and to generate effective hydrogen production, we investigated the effects of high temperature $H_2SO_4$ feed rate and cooling water rate to pump parts with fixed frequency needed to reciprocate motion and a simulation was conducted at each condition. In the fixed frequency and cooling water inlet flow rate of 0.5 Hz and 3.9 kg/s, we changed the high temperature $H_2SO_4$ flow rate to 47.46 kg/s (it is 105 % of 45.2 kg/s), 49.72 kg/s (110 %), and 51.98 kg/s (115 %). Also, at 0.5 Hz and 45.2 kg/s of frequency and high temperature $H_2SO_4$ flow, the thermal hydraulic analysis was performed at the condition of 95 % (3.705 kg/s), 90 % (3.51 kg/s), and 85 % (3.315 kg/s). In overall simulation cases, the physical properties of materials are more influential to the temperature increase in the pump part rather than the changes on the feed rate of high temperature $H_2SO_4$ and cooling water. A continuous operation of pump was also capable even if the excess feed of high temperature $H_2SO_4$ of about 15 % or the less feed of cooling water of about 15 % were performed, respectively. When the increasing feed of high temperature $H_2SO_4$ of up to 5 %, 10 %, and 15 % were compared with base flow (45.2 kg/s), the deviation of time period rose to a certain temperature and ranged from 0 to 4.5 s in the same position (same material). In case of cooling water, the deviation of time period rose to a certain temperature and ranged from 0 to 5.9 s according to the decreasing feed changes of cooling water at 5 %, 10 %, and 15 % compared to a base flow (3.9 kg/s). Finally, the additional researches related to the two different materials (Teflon and STS for Pitch and End-plate), which are concerned about the effects of temperature changes to the parts contacting different materials, are needed, and we have a plan to conduct a follow-up study.

• 수산해양기술연구
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• 제39권2호
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• pp.152-157
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• 2003

Most Recently, with rapid development in marine industries such as marine structures and ship, there occurs much interest in the study of corrosion characteristics which play an important role in design of cooling water system like heat-exchanger. Especially, as operating environment of fresh cooling water system in vessels is acidified, this system is seriously corroded. In this study, to study on the corrosion characteristics of Al-alloy shell for cooler, the electrochemical polarization test of materials for the marine fresh water cooler such as Al-alloy, Cu and naval brass was carried out in fresh water. And thus the polarization resistance and anodic polarization behavior of Al-alloy, Cu and naval brass are investigated. Also, galvanic corrosion characteristics of Al-alloy coupled with Cu and naval brass is considered. The main results obtained are as follows ; (1) The current density of corrosion is high in order of Al-alloy > naval brass > Cu (2) As anodic potential increases, the corrosion resistance of naval brass is better than that of Cu. (3) The galvanic corrosion of Al-alloy coupled with Cu and naval brass is activated than corrosion of Al-alloy.

• 동력기계공학회지
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• 제5권1호
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• pp.57-63
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• 2001

In the present study, an interactive mode of the computing system has been developed for the hydraulic analysis of the circulating waters in the industrial pipings. The system consists of three separated modules, which are linked together with common graphical user interfaces. Application to the design of the cooling sea-water system for the ships was demonstrated to be very reliable and practical in support of design activities.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.1113-1119
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• 2005

The power electric system is one of the most concerning factor for the reliability of the electric propulsion ship. operation in higher temperature decreases the device's reliability and power efficiency. the management of power loss and temperature of switching devices is indispensable for the reliability fo the power electric system. In this paper, IGBT chip of the switching devices is modeled and MIIR(Motor with Inverter Internal to Rotor)type of the propulsion motors is used. these parts interact with each other to calculate the loss and temperature of device. calculated Results is modeled and designed of the control and monitoring system for the electric propulsion system.

• 해양환경안전학회지
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• 제11권2호
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• pp.109-115
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• 2005

하이드로사이클론은 다양한 산업 방면의 고$\cdot$액 분리를 위해 널리 사용되어왔다. 왜냐하면 하이드로사이클론의 적당한 응용으로 폭넓은 범위의 입자에 적용이 가능하기 때문이다. 불순물을 함유한 해수가 펌프나 열교환기로 흘러가면 그것은 해수 냉각시스템의 효율을 저하시키는 원인이 된다. 본 연구에서는 하이드로사이클론을 이용한 해수 냉각시스템에서 불순물을 분리하는 몇가지 방법을 제시했다. 설계의 영향을 미치는 인자로서 고체농도, 사이클론 입구압력, 하부배출구의 직경과 유량에 따른 하이드로사이클론의 분리효율에 대해 연구를 하였다. 이 연구의 결과는 다음과 같다. 1) 고형물질의 농도가 감소할수록 고$\cdot$액 분리의 효율이 증가하였다. 2) 사이클론 입구압력이 증가함에 따라 분리효율이 증가하였다. 결과적으로 이 연구에서는 하이드로사이클론을 기계류 냉각시스템의 전처리장치로 사용한다면 엔진시스템에서 예상치 못했던 사고를 방지할 수 있을 것이다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2004년도 추계학술발표회
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• pp.109-115
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• 2004

하이드로사이클론은 다양한 산업 방면의 고$\cdot$액 분리를 위해 널리 사용되어왔다 왜냐하면 하이드로사이클론의 적당한 응용으로 폭넓은 범위의 입자에 적용이 가능하기 때문이다. 불순물을 함유한 해수가 펌프나 열교환기로 흘러가면 그것은 해수 냉각시스템의 효율을 저하시키는 원인이 된다. 본 연구에서는 하이드로사이클론을 이용한 해수 냉각시스템에서 불순물을 분리하는 몇가지 방법을 제시했다. 설계의 영향을 미치는 인자로서 고체농도, 사이클론 입구압력, 하부배출구의 직경과 유량에 따른 하이드로사이클론의 분리효율에 대해 연구를 하였다 이 연구의 결과는 다음과 같다. 1) 고형물질의 농도가 감소할수록 고$\cdot$액 분리의 효율이 증가하였다. 2)사이클론 입구압력이 증가함에 따라 분리효율이 증가하였다. 결과적으로 이 연구에서는 하이드로사이클론을 기계류 냉각시스템의 전처리장치로 사용한다면 엔진시스템에서 예상치 못했던 사고를 방지할 수 있을 것이다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권10호
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• pp.1002-1010
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• 2015

Natural gas hydrates are newly emerging as an environment-friendly source of energy to substitute for fossil fuels in the 21stcentury.NGHs are reported to holds much amounts of natural gas (up to 182 standard volumes of gas per volume of hydrate); they are easy to store and safe to carry at about minus 20 degree Celsius under atmospheric pressure because of the self-preservation phenomenon of gas hydrates. The transporting method by gas-ice-hydrate ship carriers has been introduced and developed by a variety of industry and research institutions. Our team has been conducted to develop NGH total systems, including a breakthrough NGH carrier for sea transportation, since 2011. The NGH pellet carrier does not require a separate cooling system for cargo, and the initial temperature is maintained through insulation of the cargo tanks throughout the transport to the final destination. The heat conducted from the exterior and passing through the insulation material of the hull should be cut off as much as possible, but heat inflow inside the cargo tank from an external source is inevitable during transport. In this study, the heat transfer in a cargo tank of a 115K NGH carrier was analyzed through simulation with a commercial CFD code to estimate the boil-off gas/boil-off rate on the developed carrier and understand major hazards that could significantly impact the safety of the vessel.

• Journal of Advanced Marine Engineering and Technology
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• 제33권4호
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• pp.484-496
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• 2009

The strengthened regulations for atmospheric emissions from ships like MARPOL Annex VI have caused a necessity of new, alternative power system in ships for the low pollutant emissions and the high energy efficiency. This paper attempts to investigate the configuration of SOFC/GT hybrid power system for LNG tanker taking into account the safety and to analyze the influence of design parameters on the system performance. The simulation results provide the basic data for the design and efficiency improvement of SOFC/GT hybrid system and indicate the guidelines for the safe system operation.