• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.4
• /
• pp.502-507
• /
• 2014

In this paper, performance characteristics of cycles were studied when mixed working fluid was used for ocean thermal energy conversion (OTEC). Among the various mixed refrigerants for industrial heat-pump, R32/R152a used in ocean thermal energy conversion system. For simulations, R32/R152a were used in existing closed cycle and Kalina cycle which is used only ammonia and water as mixed refrigerant. Temperature of the warm heat source was 26 and 29 celsius degree, temperature of the cold heat source was 5 celsius degree. In results of simulation, Gross power of the closed cycle on R32 was 22kW, and efficiency of the cycle was 2.02%. When the mixed refrigerant of R32/R152a, in the ratio of 90 to 10, gross power of the closed cycle was 29.93kW, and efficiency of the cycle was 2.78%. Gross power and cycle efficiency of R32/R152a increased by 36% and 37% than those of existing single refrigerant. Additionally, the same simulations were conducted in Kalina cycle with the same various composition ratio of mixed refrigerant.

• Solar Energy
• /
• v.17 no.4
• /
• pp.23-33
• /
• 1997

In this paper, performance of various working fluids is evaluated for the closed Ocean Thermal Energy Conversion(OTEC) power plant operating on Rankine cycle. The evaporator and condenser are modeled via UA and LMTD method while turbine and pump are modeled by specifying isentropic efficiencies. R22, Propane, Propylene, R134a, R125, R143a, R32, R410A and Ammonia are used as working fluids. Results show that newly developed fluids such as R410A and R32 that do not cause stratospheric ozone layer depletion perform as well as R22 and ammonia. The superheat at the evaporator exit and subcooling at the condenser exit do not affect the performance of the simple OTEC power cycle. Turbine efficiency and heat exchanger size influence greatly the performance of the Rankine cycle. Finally, it was shown that closed OTEC power plants can practically generate electricity when the difference in warm and cold sea water inlet temperatures is greater than $20^{\circ}C$.

• Journal of Ocean Engineering and Technology
• /
• v.25 no.1
• /
• pp.80-84
• /
• 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.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.238.2-238.2
• /
• 2010

Recently, environmental pollution and energy depletion problems have been issued over the world. For this reason, many renewable systems have been developing. Of these, the Ocean Thermal Energy Conservation(OTEC) is drawing attention as the upcoming alternative energy source. In this paper, the efficiency of each of OTEC which harness the effluent from nuclear power plant was analyzed by using computer calculation. The result, shows that Ul-jin Nuclear Power Plant is the best place geographically and the regenerative cycle is most outstanding performance cycle for OTEC. The difference of temperature between surface water and deep water temperature should be greater than $20^{\circ}C$ in order to increase the efficiency.

• Proceedings of the KSME Conference
• /
• 2000.11b
• /
• pp.234-240
• /
• 2000

The Energy is the basis for almost all industrial activities and domestic needs. But recently there are increasing concerns internationally over environmental problems and consequent climate changes caused by the excessive use of fossil fuels. Furthermore the price of crude oil is increasing steadily with unstable supplies. In order to solve these national energy problems, the utilization of Ocean Energy is introduced as one of the best alternative technologies for the future. OTEC Power Plant has been installed at the West Inchon Power Plant Site. Temperature differences of $20{\sim}25^{\circ}C$ have been utilized for plant operations, where R22 is used as a working fluid. The system is composed of low pressure turbine, plate type heat exchanger, and pumps. In the present investigation the experimental results, such as gross power, net power and objective function, are analysed when temperature differences change from the reference design point.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2012.06a
• /
• pp.239-239
• /
• 2012

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2011.06a
• /
• pp.41-41
• /
• 2011

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2012.06a
• /
• pp.218-218
• /
• 2012

• 월간 기계설비
• /
• s.258
• /
• pp.68-70
• /
• 2012

평창올림픽 빙상장에 해양심층수를 이용한 냉난방시스템 가동 방안이 추진된다. 국토해양부는 태양광이 도달하지 않는 수심 200m 아래의 해양심층수가 연중 $2^{\circ}C$ 정도를 유지하는 점을 이용해 세계 최초로 올림픽 빙상장에 한국해양연구원의 '해수냉난방시스템' 및 '해수온도차 발전' 연구개발 사업 성과를 적용한다고 밝혔다. 이번 기술이 전기에어컨이나 흡수식 냉동기 등에 적용되면 기존 시스템에 비해 에너지는 60%, 비용은 82%, 이산화탄소 배출량은 64% 줄어들게 된다.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.18 no.1
• /
• pp.22-28
• /
• 2015

The design on a riser in 1MW OTEC system is performed. The minimum diameter of the riser is decided depending on intake quantity of deep-sea water to supply an OTEC cycle. An applicable pipe material is selected from analyzing the properties of commercial pipes. The selected HDPE pipe with the low density and strength is reinforced with a lumped block attached at the end of and wire ropes along the riser. A lumped block, connected to a floating structure by wire ropes, with 25% and 50% weight of a GFRP riser is designed to be attached the end of a riser. The structural safety of the HDPE riser with wire rope supporting axial loads induced by a lumped block is analyzed under the harsh ocean environmental condition near Hawaii ocean with the numerical method. The final dimension of the riser and accessories is determined considering the economic point of view. The designed riser will be applicable to the construction of the 1 MW OTEC pilot plant.