Thermodynamic analysis and optimization of a 10MW OTEC Rankine cycle in Reunion Island with the equivalent Gibbs system method and generic optimization program GenOpt

Sinama, Frantz; Martins, Matthieu; Journoud, Audrey; Marc, Olivier; Lucas, Franck

doi:10.1016/j.apor.2015.07.006

Cited by 16 publications

(11 citation statements)

References 11 publications

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“…Yeh et al found a decrease of 35% for the same temperature drop in the cold seawater, but warm seawater was fixed at 25 • C, instead of 30 • C in the present study [30]. Sinama et al found a 40% decrease when the warm seawater temperature dropped from 28 • C to 25 • C against 32% in this study for the same seawater temperature values [17]. Additionally, for the same temperature change, Uehara and Ikegami showed a decrease of 44% in the net power output of the OTEC power plant [23].…”

Section: Carnot Cycle Resultssupporting

confidence: 44%

“…For a change of 5 • C in the seawater source temperature, the calculated drop in w net,max was 45%. The difference in the decrease of the net power output with other studies can be explained by the fact that the authors considered water ducting as well as the working fluid circulation pump [17,23,30,31]. Therefore, when the temperature difference decreases, the gross power output greatly decreases, whereas losses due to pumping and pressure drop hardly change.…”

Section: Carnot Cycle Resultsmentioning

confidence: 89%

“…In OTEC, heat exchangers allow heat harvest and are pointed out by many studies as one of the most important parts of the system to investigate. Sinama et al performed an OTEC cycle optimization by minimizing the destroyed exergy [17]. The study presents a sensitivity analysis that shows the role of heat exchangers in an OTEC cycle as well as the importance of optimizing them or developing more suitable ones.…”

Section: Introductionmentioning

confidence: 99%

“…A simplified method was developed to evaluate and then maximize the net power output of an OTEC system for a given heat exchanger. As it is one of the most expensive components, it is necessary to select the heat exchanger that leads to the highest net power output for a minimal amount of material [16][17][18]. This study, therefore, focused on the net power output per unit of the heat exchanger surface area.…”

Section: Introductionmentioning

confidence: 99%

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OTEC Maximum Net Power Output Using Carnot Cycle and Application to Simplify Heat Exchanger Selection

Fontaine

Yasunaga

Ikegami

2019

Entropy

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Ocean thermal energy conversion (OTEC) uses the natural thermal gradient in the sea. It has been investigated to make it competitive with conventional power plants, as it has huge potential and can produce energy steadily throughout the year. This has been done mostly by focusing on improving cycle performances or central elements of OTEC, such as heat exchangers. It is difficult to choose a suitable heat exchanger for OTEC with the separate evaluations of the heat transfer coefficient and pressure drop that are usually found in the literature. Accordingly, this paper presents a method to evaluate heat exchangers for OTEC. On the basis of finite-time thermodynamics, the maximum net power output for different heat exchangers using both heat transfer performance and pressure drop was assessed and compared. This method was successfully applied to three heat exchangers. The most suitable heat exchanger was found to lead to a maximum net power output 158% higher than the output of the least suitable heat exchanger. For a difference of 3.7% in the net power output, a difference of 22% in the Reynolds numbers was found. Therefore, those numbers also play a significant role in the choice of heat exchangers as they affect the pumping power required for seawater flowing. A sensitivity analysis showed that seawater temperature does not affect the choice of heat exchangers, even though the net power output was found to decrease by up to 10% with every temperature difference drop of 1 °C.

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Section: Carnot Cycle Resultssupporting

confidence: 44%

Section: Carnot Cycle Resultsmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

OTEC Maximum Net Power Output Using Carnot Cycle and Application to Simplify Heat Exchanger Selection

Fontaine

Yasunaga

Ikegami

2019

Entropy

View full text Add to dashboard Cite

show abstract

“…Moreover, solar-boosted cycles have been proposed as a way to increase the available temperature difference between the turbine inlet and outlet [8][9][10][11][12]. The optimization evaluation method is proposed based on the Carnot cycle thermal efficiency [13].…”

Section: Introductionmentioning

confidence: 99%

Basic Heat Exchanger Performance Evaluation Method on OTEC

Yasunaga

Noguchi

Morisaki

et al. 2018

JMSE

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Ocean thermal energy conversion (OTEC) harvests the power from the thermal energy in the ocean, which is reserved in the ocean as the temperature difference between warm surface and cold deep seawaters. In the energy conversion, the heat exchangers transfer the thermal energy to the heat engine, which converts it into power. The pressure drops yielded by piping, valve and heat exchangers cause pump loads, which show significant negative power with respect to net power in OTEC. The heat transfer performance and the pressure drop in heat exchanger depend on the types and shapes of each heat transfer area. Generally, heat exchangers with higher friction factors yield higher heat transfer performance and vice versa. However, heat transfer performance and pressure drop are separately evaluated and there is no comprehensive performance evaluation index for OTEC power takeoff. Therefore, this research proposes a new simplified overall performance evaluation method for heat exchangers, which can be comprehensively and easily applied and takes into consideration the heat transfer performance and the pressure drop. The evaluation results on plate-type heat exchangers show that the overall performance in each heat exchanger are elucidated and are quantitatively compared.

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Reliability assessment of the ocean thermal energy conversion systems through Monte Carlo simulation considering outside temperature variation

Ghaedi,

Sedaghati,

Mahmoudian

et al. 2023

J Mar Sci Technol

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The ocean thermal energy conversion (OTEC) systems, as renewable energy-based power plants, have the potential to play a significant role in meeting future electricity demands due to the vast expanse of the world's oceans. These systems employ the temperature difference between surface ocean waters and deep ocean waters to drive a thermodynamic cycle and produce electricity. The temperature of deep ocean waters, approximately 1000 m below the surface, is approximately 4 °C, while surface ocean temperatures typically range between 20 and 30 °C. The generated power of OTEC systems is dependent on these temperature differences and may vary with changes in surface ocean temperatures. In this study, the main focus is to find the impact of temperature variation on the failure rates of OTEC system components and the generated power output of these plants. The findings indicate that as the demand for the power system increases, its reliability decreases. In order to improve the reliability of the power system, the integration of a new generation unit, such as the close cycle OTEC power plant under investigation, could be necessary. The findings also indicate the importance of considering temperature variation in the evaluation of the reliability of such types of power plants based on renewable energy.

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Thermodynamic analysis and optimization of a 10MW OTEC Rankine cycle in Reunion Island with the equivalent Gibbs system method and generic optimization program GenOpt

Cited by 16 publications

References 11 publications

OTEC Maximum Net Power Output Using Carnot Cycle and Application to Simplify Heat Exchanger Selection

OTEC Maximum Net Power Output Using Carnot Cycle and Application to Simplify Heat Exchanger Selection

Basic Heat Exchanger Performance Evaluation Method on OTEC

Reliability assessment of the ocean thermal energy conversion systems through Monte Carlo simulation considering outside temperature variation

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