• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2304-2308
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• 2003

Ocean thermal energy conversion (OTEC) is an effective method of power generation, which has a small impact on the environment and can be utilized semi-permanently. This paper describes a dynamic model for a pilot OTEC plant built by the Institute of Ocean Energy, Saga University, Japan. This plant is based on Uehara cycle, in which binary mixtures of ammonia and water is used as the working fluid. Some simulation results attained by this model and the analysis of the results are presented. The developed computer simulation can be used to actual practice effectively, such as stable control in a steady operation, optimal determination of the plant specifications for a higher thermal efficiency and evaluation of the economic prospects and off-line training for the operators of OTEC plant.

• 신재생에너지
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• 제6권3호
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• pp.22-29
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• 2010

The concept of Ocean Thermal Energy Conversion (OTEC) is simple and various types of OTEC have been proposed and tried. However the location of OTEC is limited because OTEC requires $20^{\circ}C$ of temperature difference as a minimum, so most of OTEC plants were constructed and experimented in tropical oceans. To solve this we proposed the modified OTEC which uses condenser discharged thermal energy of existing fossil or nuclear power plants. We call this system CTEC (Condenser Thermal Energy Conversion) as this system directly uses $32^{\circ}C$ partially saturated steam in condenser instead of $20{\sim}25^{\circ}C$ surface sea water as heat source. Increased temperature difference can improve thermal efficiency of Rankine cycle, but CTEC should be located near existing plant condenser and the length of cold water pipe between CTEC and deep cold sea water also increase. So friction loss also increases. Calculated result shows the change of efficiency, pumping power, net power and other parameters of modeled 7.9 MW CTEC at given condition. The calculated efficiency of CTEC is little larger than that of typical OTEC as expected. By proper location and optimization, CTEC could be considered another competitive renewable energy system.

• KEPCO Journal on Electric Power and Energy
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• 제5권3호
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• pp.215-222
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• 2019

This work is experimental study of 10 kW specialized Combined Ocean Thermal Energy Conversion. We propose a C-OTEC technology that directly uses exhaust thermal energy from power station condensers to heat the working fluid (R134a), and tests the feasibility of such power station by designing, manufacturing, installing, and operating a 10 kW-pilot facility. Power generation status was monitored by using exhaust thermal energy from an existing power plant located on the east coast of the Korean peninsula, heat exchange with 300 kW of heat capacity, and a turbine, which can exceed enthalpy efficiency of 45%. Output of 8.5 kW at efficiency of 3.5% was monitored when the condenser temperature and seawater temperature are $29^{\circ}C$ and $7.5^{\circ}C$, respectively. The evaluation of the impact of large-capacity C-OTEC technology on power station confirmed the increased value of the technology on existing power generating equipment by improving output value and reducing hot waste water. Through the research result, the technical possibility of C-OTEC has been confirmed, and it is being conducted at 200 kW-class to gain economic feasibility. Based on the results, authors present an empirical study result on the 200 kW C-OTEC design and review the impact on power plant.

• 한국해양공학회지
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• 제25권1호
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• pp.80-84
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• 2011

The cycle performance of closed ocean thermal energy conversion (OTEC) system with 50 kW gross power was evaluated to obtain the basic data for the optimal design of OTEC using waste heat such as solar power, discharged heat from condenser of power plant. The basic thermodynamic model for OTEC is Rankine cycle, and the surface seawater and deep seawater were used for the heat source of evaporator and condenser, respectively. The cycle performance such as efficiency, heat exchanger capacity, etc. was analyzed on the variation of temperature increase by waste heat. The cycle efficiency increased and necessary capacity of evaporator and condenser decreased under 50kW gross power with respect to the temperature increase of working fluid. Also, when the temperature increase is about $13.5^{\circ}C$, the heat which can be used is generated. By generator with 0.9 effectiveness under the simulated condition, the cycle efficiency was improved approximately 3.0% comparing with the basic cycle.

• Journal of Advanced Marine Engineering and Technology
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• 제34권4호
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• pp.470-476
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• 2010

발전소 온배수 및 폐열을 이용한 1 MW급 폐쇄형 해양온도차발전 사이클에 대한 성능을 비교 분석하였다. 폐쇄형 해양온도차발전 사이클에 대한 열역학적 모델은 랭킨 사이클이고, 기화기 증발 열원으로 발전소 온배수를 이용하여 사이클 효율, 기화기 및 응축기 열량 등 사이클 성능을 비교 분석하였다. 발전소 온배수 온도가 증가함에 따라 기화기 내 증발 포화압력은 상승하게 되고 그로 인해 사이클 효율은 증가하였고, 총 출력 1 MW에 필요한 기화기 및 응축기 용량은 감소하였다. 따라서 발전소 온배수는 폐쇄형 해양온도차발전에서 주요한 열원으로 사용될 수 있음을 알 수 있었다. 또한, 주위 이용 가능한 폐열이 있을 때 기화기 출구 작동유체와 열교환시켜 터빈으로 유입되는 작동유체의 온도를 상승시킨다면 사이클 효율은 크게 증가할 것이다.

• 동력기계공학회지
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• 제18권5호
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• pp.88-93
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• 2014

In this paper, the performance analysis of condensation and evaporation capacity, turbine work and efficiency of the OTEC power system using vapor-liquid Ejector is presented to offer the basic design data for the operating parameters of the system. The working fluid used in this system is $CO_2$. The operating parameters considered in this study include the vapor quality at heat exchanger outlet, pressure ratio of ejector and inlet pressure of low turbine, mass flow ratio of separator at condenser outlet. The main results were summarized as follows. The efficiency of the OTEC power cycle has an enormous effect on the mass flow ratio of separator at condenser outlet. With a thorough grasp of these effects, it is possible to design the OTEC power cycle proposed in this study.

• 설비공학논문집
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• 제24권7호
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• pp.591-597
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• 2012

For the past few years, the concern for clean energy has been greatly increased. Ocean thermal Energy Conversion(OTEC) power plants are studied as a viable option for the supply of clean energy. In this study, we examined the thermodynamic performance of the OTEC power system for the production of electric power. Computer simulation programs were developed under the same condition and various working fluids for closed Rankine cycle, regenerative cycle, Kalina cycle, open cycle, and hybrid cycle. The results show that the regenerative cycle showed the best system efficiency. And then we examined the thermodynamic performance of regenerative cycle OTEC power system using the condenser effluent from Uljin nuclear power plant instead of the surface water. The highest system efficiency of the condition was 4.55% and the highest net power was 181 MW.

• Journal of Advanced Marine Engineering and Technology
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• 제36권8호
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• pp.1151-1157
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• 2012

OTEC기술은 신재생에너지 기술 중의 하나로 따듯한 표층수와 차가운 심층수의 온도차를 이용하여 전력을 생산하는 기술이다. 작동유체의 선정과 OTEC 사이클의 상태에 따라 에너지효율과 환경적인 측면에 많은 영향을 준다. OTEC의 작동유체로는 ammonia, R22, R407C, R410A가 있다. 본 논문에서는 OTEC 시스템의 최적화를 위해 $25^{\circ}C$에서의 증발압력를 비교하였다. 또한 밀폐사이클과 재생사이클에서의 작동유체에 따른 출력과 효율에 대하여 연구하였다.

• 한국태양에너지학회 논문집
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• 제27권3호
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• pp.37-44
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• 2007

For the past few years, the concern for clean energy has been greatly increased. Ocean Thermal Energy Conversion(OTEC) power plants are studied as a viable option for the supply of clean energy. In this paper, the thermodynamic performance of OTEC cycle was examined. Computer simulation programs were developed under the same condition and various working fluids for closed Rankine cycle, regeneration cycle, Kalina cycle, open cycle and hybrid cycle. The results show that the regeneration cycle using R125 showed a 0.17 to 1.56% increase in energy efficiency, and simple Rankine cycle can generate electricity when the difference in warm and cold sea water inlet temperatures are greater than $15^{\circ}C$. Also, the cycle efficiency of OTEC power plant using the condenser effluent from nuclear power plant instead of the surface water increased about 2%.

• 한국태양에너지학회 논문집
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• 제30권3호
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• pp.124-130
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• 2010

Ocean Thermal Energy Conversion(OTEC) power plants have been examined as a viable option for supplying clean energy. This paper evaluated the thermodynamic performance of the OTEC Power system for the production of electric power and desalinated water. The results show that newly developed fluids such as R32, R125, R143a, and R410A that do not cause stratospheric ozone layer depletion perform as well as R22 and ammonia. Overall cycle efficiency of open cycle is the lowest value of 3.01% because about 10% of the gross power is used for pumping out non-condensable gas. Also, the hybrid cycle is an attempt to combine the best features and avoid the worst features of the open and closed cycles. The overall cycle efficiency of hybrid cycle is 3.44% and the amount of desalinated water is 0.0619 kg/s.