Ocean thermal energy conversion systems: The heat losses effect of the cold-water pipe
Ocean Thermal Energy Conversion (OTEC) systems are categorized as Renewable Energy Systems (RES), as the natural sea temperature difference (ΔΤ), between the surface water and the deep seawater, can be exploited either to produce electricity or to deliver a by-product. The sea water temperature vari...
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| Language: | English |
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Elsevier
2025-10-01
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| Series: | Case Studies in Thermal Engineering |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2214157X25010068 |
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| author | Lazaros Aresti Toula Onoufriou Constantine Michailides Paul Christodoulides |
| author_facet | Lazaros Aresti Toula Onoufriou Constantine Michailides Paul Christodoulides |
| author_sort | Lazaros Aresti |
| collection | DOAJ |
| description | Ocean Thermal Energy Conversion (OTEC) systems are categorized as Renewable Energy Systems (RES), as the natural sea temperature difference (ΔΤ), between the surface water and the deep seawater, can be exploited either to produce electricity or to deliver a by-product. The sea water temperature varies according to location/country, also depending on sea depth and distance from shore. Therefore, the minimum distance from shore can vary in order to meet the required ΔΤ for the system to perform in a beneficial manner. The present study investigates the effect of such cases, by examining the magnitude of the heat transfer loss of the cold-water pipes (CWPs), in terms of the outcome in the theoretical efficiency of the system. CWPs are computationally investigated using the COMSOL Multiphysics software, to assess a more accurate ΔΤ. Contrary to this study, in most literature cases the ΔΤ used in the performance estimations, is the one found on location and without any computational process. The CWP pump was also assessed in terms of required power and case. A parametric analysis of the size of the CWP, mass flowrate, pumping power, pipe material, distance from shore, and a comparison between onshore and offshore positioning of the OTEC systems is presented. Offshore systems seem to exhibit a desired lower temperature difference by up to 86 % from that of long-CWP onshore systems. Overall results indicate, even considering the non-ideal case of heat loss, OTEC systems - onshore or offshore - may become viable, but site specific ΔT estimations are required per case. |
| format | Article |
| id | doaj-art-a17cb2433f884a6fa0f0a381e461e33a |
| institution | DOAJ |
| issn | 2214-157X |
| language | English |
| publishDate | 2025-10-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Case Studies in Thermal Engineering |
| spelling | doaj-art-a17cb2433f884a6fa0f0a381e461e33a2025-08-20T03:09:34ZengElsevierCase Studies in Thermal Engineering2214-157X2025-10-017410674610.1016/j.csite.2025.106746Ocean thermal energy conversion systems: The heat losses effect of the cold-water pipeLazaros Aresti0Toula Onoufriou1Constantine Michailides2Paul Christodoulides3EMERGE Centre of Excellence, Lemesos, Cyprus; Faculty of Engineering and Technology, Cyprus University of Technology, Lemesos, CyprusEMERGE Centre of Excellence, Lemesos, Cyprus; Faculty of Engineering and Technology, Cyprus University of Technology, Lemesos, CyprusDepartment of Civil Engineering, International Hellenic University, Serres University Campus, GreeceEMERGE Centre of Excellence, Lemesos, Cyprus; Faculty of Engineering and Technology, Cyprus University of Technology, Lemesos, Cyprus; Corresponding author. EMERGE Centre of Excellence, Lemesos, Cyprus.Ocean Thermal Energy Conversion (OTEC) systems are categorized as Renewable Energy Systems (RES), as the natural sea temperature difference (ΔΤ), between the surface water and the deep seawater, can be exploited either to produce electricity or to deliver a by-product. The sea water temperature varies according to location/country, also depending on sea depth and distance from shore. Therefore, the minimum distance from shore can vary in order to meet the required ΔΤ for the system to perform in a beneficial manner. The present study investigates the effect of such cases, by examining the magnitude of the heat transfer loss of the cold-water pipes (CWPs), in terms of the outcome in the theoretical efficiency of the system. CWPs are computationally investigated using the COMSOL Multiphysics software, to assess a more accurate ΔΤ. Contrary to this study, in most literature cases the ΔΤ used in the performance estimations, is the one found on location and without any computational process. The CWP pump was also assessed in terms of required power and case. A parametric analysis of the size of the CWP, mass flowrate, pumping power, pipe material, distance from shore, and a comparison between onshore and offshore positioning of the OTEC systems is presented. Offshore systems seem to exhibit a desired lower temperature difference by up to 86 % from that of long-CWP onshore systems. Overall results indicate, even considering the non-ideal case of heat loss, OTEC systems - onshore or offshore - may become viable, but site specific ΔT estimations are required per case.http://www.sciencedirect.com/science/article/pii/S2214157X25010068Ocean thermal energy conversionOTECHeat transferOTEC cold water pipe |
| spellingShingle | Lazaros Aresti Toula Onoufriou Constantine Michailides Paul Christodoulides Ocean thermal energy conversion systems: The heat losses effect of the cold-water pipe Case Studies in Thermal Engineering Ocean thermal energy conversion OTEC Heat transfer OTEC cold water pipe |
| title | Ocean thermal energy conversion systems: The heat losses effect of the cold-water pipe |
| title_full | Ocean thermal energy conversion systems: The heat losses effect of the cold-water pipe |
| title_fullStr | Ocean thermal energy conversion systems: The heat losses effect of the cold-water pipe |
| title_full_unstemmed | Ocean thermal energy conversion systems: The heat losses effect of the cold-water pipe |
| title_short | Ocean thermal energy conversion systems: The heat losses effect of the cold-water pipe |
| title_sort | ocean thermal energy conversion systems the heat losses effect of the cold water pipe |
| topic | Ocean thermal energy conversion OTEC Heat transfer OTEC cold water pipe |
| url | http://www.sciencedirect.com/science/article/pii/S2214157X25010068 |
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