Study of available thermal energy on OTEC
Thermal efficiency is commonly applied in the power plants for the purpose of evaluating heat engines. However, the maximization of the thermal efficiency does not lead the maximization of the available power output from ocean thermal energy conversion (OTEC), which converts the finite thermal energ...
| Main Authors: | , , |
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| Format: | Article |
| Language: | Japanese |
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The Japan Society of Mechanical Engineers
2018-01-01
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| Series: | Nihon Kikai Gakkai ronbunshu |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/transjsme/84/859/84_17-00398/_pdf/-char/en |
| _version_ | 1811317750164881408 |
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| author | Takeshi YASUNAGA Takafumi MORISAKI Yasuyuki IKEGAMI |
| author_facet | Takeshi YASUNAGA Takafumi MORISAKI Yasuyuki IKEGAMI |
| author_sort | Takeshi YASUNAGA |
| collection | DOAJ |
| description | Thermal efficiency is commonly applied in the power plants for the purpose of evaluating heat engines. However, the maximization of the thermal efficiency does not lead the maximization of the available power output from ocean thermal energy conversion (OTEC), which converts the finite thermal energy stored between different temperature seawaters into work. The maximum work efficiency based on the theoretical maximum work from the ideal heat engine has been identified for evaluation; however, the implication in the available thermal energy has not yet been substantially identified. This paper theoretically reveals the available thermal energy from the ocean thermal gradient and the effective energy, which is known as the exergy, using the reference of the equilibrium temperature as the dead state. By employing the finite-time thermodynamics, the available energy and the exergy calculation methods for OTEC are obtained. For the evaluation of the systems, the normalized thermal efficiency is proposed instead of the conventional thermal efficiency and the exergy efficiency for OTEC is proposed as well. The results indicated that increases in the normalized thermal efficiency increase the power output from the OTEC system and the maximum normalized thermal efficiency conditions correspond to the maximum power output heat balance. They also showed the effectiveness of the proposed exergy for OTEC derived by entropy generation minimization. |
| first_indexed | 2024-04-13T12:15:03Z |
| format | Article |
| id | doaj.art-6f7b645110a143b597638babdc2c35f7 |
| institution | Directory Open Access Journal |
| issn | 2187-9761 |
| language | Japanese |
| last_indexed | 2024-04-13T12:15:03Z |
| publishDate | 2018-01-01 |
| publisher | The Japan Society of Mechanical Engineers |
| record_format | Article |
| series | Nihon Kikai Gakkai ronbunshu |
| spelling | doaj.art-6f7b645110a143b597638babdc2c35f72022-12-22T02:47:24ZjpnThe Japan Society of Mechanical EngineersNihon Kikai Gakkai ronbunshu2187-97612018-01-018485917-0039817-0039810.1299/transjsme.17-00398transjsmeStudy of available thermal energy on OTECTakeshi YASUNAGA0Takafumi MORISAKI1Yasuyuki IKEGAMI2Institute of Ocean Energy, Saga UniversityInstitute of Ocean Energy, Saga UniversityInstitute of Ocean Energy, Saga UniversityThermal efficiency is commonly applied in the power plants for the purpose of evaluating heat engines. However, the maximization of the thermal efficiency does not lead the maximization of the available power output from ocean thermal energy conversion (OTEC), which converts the finite thermal energy stored between different temperature seawaters into work. The maximum work efficiency based on the theoretical maximum work from the ideal heat engine has been identified for evaluation; however, the implication in the available thermal energy has not yet been substantially identified. This paper theoretically reveals the available thermal energy from the ocean thermal gradient and the effective energy, which is known as the exergy, using the reference of the equilibrium temperature as the dead state. By employing the finite-time thermodynamics, the available energy and the exergy calculation methods for OTEC are obtained. For the evaluation of the systems, the normalized thermal efficiency is proposed instead of the conventional thermal efficiency and the exergy efficiency for OTEC is proposed as well. The results indicated that increases in the normalized thermal efficiency increase the power output from the OTEC system and the maximum normalized thermal efficiency conditions correspond to the maximum power output heat balance. They also showed the effectiveness of the proposed exergy for OTEC derived by entropy generation minimization.https://www.jstage.jst.go.jp/article/transjsme/84/859/84_17-00398/_pdf/-char/enotecfinite-time thermodynamicsnormalized thermal efficiencyexergy efficiencyentropy generation minimizationmaximum power output |
| spellingShingle | Takeshi YASUNAGA Takafumi MORISAKI Yasuyuki IKEGAMI Study of available thermal energy on OTEC Nihon Kikai Gakkai ronbunshu otec finite-time thermodynamics normalized thermal efficiency exergy efficiency entropy generation minimization maximum power output |
| title | Study of available thermal energy on OTEC |
| title_full | Study of available thermal energy on OTEC |
| title_fullStr | Study of available thermal energy on OTEC |
| title_full_unstemmed | Study of available thermal energy on OTEC |
| title_short | Study of available thermal energy on OTEC |
| title_sort | study of available thermal energy on otec |
| topic | otec finite-time thermodynamics normalized thermal efficiency exergy efficiency entropy generation minimization maximum power output |
| url | https://www.jstage.jst.go.jp/article/transjsme/84/859/84_17-00398/_pdf/-char/en |
| work_keys_str_mv | AT takeshiyasunaga studyofavailablethermalenergyonotec AT takafumimorisaki studyofavailablethermalenergyonotec AT yasuyukiikegami studyofavailablethermalenergyonotec |