{"id":{"repo_id":"cadiz","oai_identifier":"oai:rodin.uca.es:10498/29235"},"canonical_url":"https://search.dev.ndltd.org/etd/cadiz/oai:rodin.uca.es:10498/29235","repository":{"repo_id":"cadiz","name":"Universidad de Cadiz","base_url":"https://rodin.uca.es/oai/request"},"display":{"title":"Nanofluids with optimised thermal properties based on metal chalcogenides with different morphology","abstract":"Over the last decades, the interest around renewable energies has increased considerably because of the growing energy demand and the environmental problems derived from fossil fuels combustion. In this scenario, concentrating solar power (CSP) is a renewable energy with a high potential to cover the global energy demand. However, improving the efficiency and reducing the cost of technologies based on this type of energy to make it more competitive is still a work in progress. One of the current lines of research is the replacement of the heat transfer fluid used in the absorber tube of parabolic trough collectors with nano-colloidal suspensions of nanomaterials in a base fluid, typically named nanofluids. Nanofluids are considered as a new generation of heat transfer fluids since they exhibit thermophysical properties improvements compared with conventional heat transfer fluids. But there are still some barriers to overcome for the implementation of nanofluids. For example, obtaining nanofluids with high stability is a priority challenge for this kind of system. Also ensuring that nanoparticles will not clog pipes or cause pressure drops. In this Doctoral Thesis, the use of transition metal dichalcogenide-based nanofluids as a heat transfer fluid in solar power plants has been investigated for the first time. Specifically, nanofluids based on one-dimensional, two-dimensional and three-dimensional MoS2 , WS2 and WSe2 nanostructures have been researched. The base fluid used in the preparation of these nanofluids is the eutectic mixture of biphenyl and diphenyl oxide typically employed as heat transfer fluid in concentrating solar power plants. Mainly two preparation methods have been explored: the liquid phase exfoliation method, and the solvothermal synthesis of the nanomaterial and its subsequent dispersion in the thermal oil by ultrasound. Experimental parameters such as surfactant concentration, time and sonication frequency for preparation of nanofluids have also been analysed. The nanofluids have been subjected to an extensive characterisation which includes the study of colloidal stability over time, characterisation of thermal properties such as isobaric specific heat or thermal conductivity, rheological properties and optical properties. The results have revealed that nanofluids based on 1D and 2D nanostructures of transition metal dichalcogenides are colloidally stable over time and exhibit improved thermal properties compared to the typical thermal fluid used in solar power plants. The most promising nanofluids are those based on MoS 2 nanosheets and those based on WSe 2 nanosheets with heat transfer coefficient improvements of 36.2% and 34.1% respectively with respect to thermal oil. Furthermore, the dramatic role of WSe2 nanosheets in enhancing optical extinction of the thermal oil suggests the use of these nanofluids in direct absorption solar collectors. In conclusion, the present work demonstrates the feasibility of using nanofluids based on transition metal dichalcogenide nanostructures as heat transfer fluids in concentrating solar power plants based on parabolic trough collectors.","abstract_html":"Over the last decades, the interest around renewable energies has increased considerably because of the growing energy demand and the environmental problems derived from fossil fuels combustion. In this scenario, concentrating solar power (CSP) is a renewable energy with a high potential to cover the global energy demand. However, improving the efficiency and reducing the cost of technologies based on this type of energy to make it more competitive is still a work in progress. One of the current lines of research is the replacement of the heat transfer fluid used in the absorber tube of parabolic trough collectors with nano-colloidal suspensions of nanomaterials in a base fluid, typically named nanofluids. Nanofluids are considered as a new generation of heat transfer fluids since they exhibit thermophysical properties improvements compared with conventional heat transfer fluids. But there are still some barriers to overcome for the implementation of nanofluids. For example, obtaining nanofluids with high stability is a priority challenge for this kind of system. Also ensuring that nanoparticles will not clog pipes or cause pressure drops. In this Doctoral Thesis, the use of transition metal dichalcogenide-based nanofluids as a heat transfer fluid in solar power plants has been investigated for the first time. Specifically, nanofluids based on one-dimensional, two-dimensional and three-dimensional MoS2 , WS2 and WSe2 nanostructures have been researched. The base fluid used in the preparation of these nanofluids is the eutectic mixture of biphenyl and diphenyl oxide typically employed as heat transfer fluid in concentrating solar power plants. Mainly two preparation methods have been explored: the liquid phase exfoliation method, and the solvothermal synthesis of the nanomaterial and its subsequent dispersion in the thermal oil by ultrasound. Experimental parameters such as surfactant concentration, time and sonication frequency for preparation of nanofluids have also been analysed. The nanofluids have been subjected to an extensive characterisation which includes the study of colloidal stability over time, characterisation of thermal properties such as isobaric specific heat or thermal conductivity, rheological properties and optical properties. The results have revealed that nanofluids based on 1D and 2D nanostructures of transition metal dichalcogenides are colloidally stable over time and exhibit improved thermal properties compared to the typical thermal fluid used in solar power plants. The most promising nanofluids are those based on MoS 2 nanosheets and those based on WSe 2 nanosheets with heat transfer coefficient improvements of 36.2% and 34.1% respectively with respect to thermal oil. Furthermore, the dramatic role of WSe2 nanosheets in enhancing optical extinction of the thermal oil suggests the use of these nanofluids in direct absorption solar collectors. In conclusion, the present work demonstrates the feasibility of using nanofluids based on transition metal dichalcogenide nanostructures as heat transfer fluids in concentrating solar power plants based on parabolic trough collectors.","abstract_has_math":false,"creators":["Martínez Merino, Paloma"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Navas Pineda, Francisco Javier","Alcántara Puerto, Rodrigo"],"committee_chairs":[],"committee_members":[],"year":2023,"date_issued":"2023","date_published":"2023","updated_at":"2026-07-24T01:29:44Z","subjects":["concentrating solar power","nanofluids","transition metal dichalcogenide","energía solar de concentración","nanofluidos","dicalcogenuros de metales de transición"],"languages":["eng"],"rights":["Attribution-NonCommercial-NoDerivatives 4.0 Internacional"],"rights_urls":["http://creativecommons.org/licenses/by-nc-nd/4.0/"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10498/29235","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Navas Pineda, Francisco Javier","Alcántara Puerto, Rodrigo"]},{"key":"dc:contributor.other","label":"Dc Contributor Other","values":["Química Física"]},{"key":"dc:creator","label":"Author","values":["Martínez Merino, Paloma"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2023-09-14T11:25:32Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2023-09-14T11:25:32Z"]},{"key":"dc:date.issued","label":"Date","values":["2023"]},{"key":"dc:type","label":"Dc Type","values":["doctoral thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["concentrating solar power","nanofluids","transition metal dichalcogenide","energía solar de concentración","nanofluidos","dicalcogenuros de metales de transición"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Attribution-NonCommercial-NoDerivatives 4.0 Internacional"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://creativecommons.org/licenses/by-nc-nd/4.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10498/29235"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Over the last decades, the interest around renewable energies has increased considerably because of the growing energy demand and the environmental problems derived from fossil fuels combustion. In this scenario, concentrating solar power (CSP) is a renewable energy with a high potential to cover the global energy demand. However, improving the efficiency and reducing the cost of technologies based on this type of energy to make it more competitive is still a work in progress. One of the current lines of research is the replacement of the heat transfer fluid used in the absorber tube of parabolic trough collectors with nano-colloidal suspensions of nanomaterials in a base fluid, typically named nanofluids. Nanofluids are considered as a new generation of heat transfer fluids since they exhibit thermophysical properties improvements compared with conventional heat transfer fluids. But there are still some barriers to overcome for the implementation of nanofluids. For example, obtaining nanofluids with high stability is a priority challenge for this kind of system. Also ensuring that nanoparticles will not clog pipes or cause pressure drops. In this Doctoral Thesis, the use of transition metal dichalcogenide-based nanofluids as a heat transfer fluid in solar power plants has been investigated for the first time. Specifically, nanofluids based on one-dimensional, two-dimensional and three-dimensional MoS2 , WS2 and WSe2 nanostructures have been researched. The base fluid used in the preparation of these nanofluids is the eutectic mixture of biphenyl and diphenyl oxide typically employed as heat transfer fluid in concentrating solar power plants. Mainly two preparation methods have been explored: the liquid phase exfoliation method, and the solvothermal synthesis of the nanomaterial and its subsequent dispersion in the thermal oil by ultrasound. Experimental parameters such as surfactant concentration, time and sonication frequency for preparation of nanofluids have also been analysed. The nanofluids have been subjected to an extensive characterisation which includes the study of colloidal stability over time, characterisation of thermal properties such as isobaric specific heat or thermal conductivity, rheological properties and optical properties. The results have revealed that nanofluids based on 1D and 2D nanostructures of transition metal dichalcogenides are colloidally stable over time and exhibit improved thermal properties compared to the typical thermal fluid used in solar power plants. The most promising nanofluids are those based on MoS 2 nanosheets and those based on WSe 2 nanosheets with heat transfer coefficient improvements of 36.2% and 34.1% respectively with respect to thermal oil. Furthermore, the dramatic role of WSe2 nanosheets in enhancing optical extinction of the thermal oil suggests the use of these nanofluids in direct absorption solar collectors. In conclusion, the present work demonstrates the feasibility of using nanofluids based on transition metal dichalcogenide nanostructures as heat transfer fluids in concentrating solar power plants based on parabolic trough collectors.","En las últimas décadas, el interés en torno a las energías renovables ha aumentado considerablemente debido a la creciente demanda energética y a los problemas medioambientales derivados de la combustión de combustibles fósiles. En este escenario, la energía solar de concentración (CSP) es una energía renovable con un alto potencial para cubrir la demanda energética mundial. Sin embargo, es necesario trabajar para mejorar la eficiencia y reducir el coste de las tecnologías basadas en este tipo de energía con el objetivo de hacerla más competitiva. Una de las líneas de investigación actuales es la sustitución del fluido caloportador utilizado en el tubo absorbedor de los colectores cilindroparabólicos por suspensiones nanocoloidales de nanomateriales en un fluido base, típicamente denominados nanofluidos. Los nanofluidos se consideran una nueva generación de fluidos de transferencia de calor, ya que presentan mejoras en sus propiedades termofísicas en comparación con los fluidos de transferencia de calor convencionales. Pero aún quedan algunos obstáculos por superar para la aplicación de los nanofluidos. Por ejemplo, obtener nanofluidos con alta estabilidad es un reto prioritario en este tipo de sistemas. También garantizar que las nanopartículas no obstruyan las tuberías ni provoquen caídas de presión. En esta Tesis Doctoral se ha investigado por primera vez el uso de nanofluidos basados en dicalcogenuros de metales de transición como fluido caloportador en centrales solares. En concreto, se han investigado nanofluidos basados en nanoestructuras unidimensionales, bidimensionales y tridimensionales de MoS2, WS2 y WSe2. El fluido base utilizado en la preparación de estos nanofluidos es la mezcla eutéctica de bifenilo y óxido de difenilo empleada habitualmente como fluido de transferencia de calor en las centrales de concentración de energía solar. Se han explorado principalmente dos métodos de preparación: el método de exfoliación en fase líquida y la síntesis solvotermal del nanomaterial y su posterior dispersión en el aceite térmico mediante ultrasonidos. También se han analizado parámetros experimentales como la concentración de surfactante, el tiempo y la frecuencia de sonicación para la preparación de los nanofluidos. Los nanofluidos han sido sometidos a una extensa caracterización que incluye el estudio de la estabilidad coloidal a lo largo del tiempo, la caracterización de propiedades térmicas como el calor específico isobárico o la conductividad térmica, propiedades reológicas y propiedades ópticas. Los resultados han revelado que los nanofluidos basados en nanoestructuras 1D y 2D de dicalcogenuros de metales de transición son coloidalmente estables en el tiempo y presentan propiedades térmicas mejoradas en comparación con el fluido térmico típico utilizado en las centrales solares. Los nanofluidos más prometedores son los basados en nanoláminas de MoS2 y los basados en nanoláminas de WSe2, con mejoras del coeficiente de transferencia térmica del 36,2% y el 34,1%, respectivamente, con respecto al aceite térmico. Además, el espectacular papel de las nanoláminas de WSe2 en la mejora de la extinción óptica del aceite térmico sugiere el uso de estos nanofluidos en colectores solares de absorción directa. En conclusión, el presente trabajo demuestra la viabilidad del uso de nanofluidos basados en nanoestructuras de dicalcogenuros de metales de transición como fluidos de transferencia de calor en centrales solares de concentración basadas en colectores cilindro-parabólicos."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Nanofluids with optimised thermal properties based on metal chalcogenides with different morphology"]}]}],"canonical_facts":{"dc:contributor.advisor":["Navas Pineda, Francisco Javier","Alcántara Puerto, Rodrigo"],"dc:contributor.other":["Química Física"],"dc:creator":["Martínez Merino, Paloma"],"dc:date.accessioned":["2023-09-14T11:25:32Z"],"dc:date.available":["2023-09-14T11:25:32Z"],"dc:date.issued":["2023"],"dc:description.abstract":["Over the last decades, the interest around renewable energies has increased considerably because of the growing energy demand and the environmental problems derived from fossil fuels combustion. In this scenario, concentrating solar power (CSP) is a renewable energy with a high potential to cover the global energy demand. However, improving the efficiency and reducing the cost of technologies based on this type of energy to make it more competitive is still a work in progress. One of the current lines of research is the replacement of the heat transfer fluid used in the absorber tube of parabolic trough collectors with nano-colloidal suspensions of nanomaterials in a base fluid, typically named nanofluids. Nanofluids are considered as a new generation of heat transfer fluids since they exhibit thermophysical properties improvements compared with conventional heat transfer fluids. But there are still some barriers to overcome for the implementation of nanofluids. For example, obtaining nanofluids with high stability is a priority challenge for this kind of system. Also ensuring that nanoparticles will not clog pipes or cause pressure drops. In this Doctoral Thesis, the use of transition metal dichalcogenide-based nanofluids as a heat transfer fluid in solar power plants has been investigated for the first time. Specifically, nanofluids based on one-dimensional, two-dimensional and three-dimensional MoS2 , WS2 and WSe2 nanostructures have been researched. The base fluid used in the preparation of these nanofluids is the eutectic mixture of biphenyl and diphenyl oxide typically employed as heat transfer fluid in concentrating solar power plants. Mainly two preparation methods have been explored: the liquid phase exfoliation method, and the solvothermal synthesis of the nanomaterial and its subsequent dispersion in the thermal oil by ultrasound. Experimental parameters such as surfactant concentration, time and sonication frequency for preparation of nanofluids have also been analysed. The nanofluids have been subjected to an extensive characterisation which includes the study of colloidal stability over time, characterisation of thermal properties such as isobaric specific heat or thermal conductivity, rheological properties and optical properties. The results have revealed that nanofluids based on 1D and 2D nanostructures of transition metal dichalcogenides are colloidally stable over time and exhibit improved thermal properties compared to the typical thermal fluid used in solar power plants. The most promising nanofluids are those based on MoS 2 nanosheets and those based on WSe 2 nanosheets with heat transfer coefficient improvements of 36.2% and 34.1% respectively with respect to thermal oil. Furthermore, the dramatic role of WSe2 nanosheets in enhancing optical extinction of the thermal oil suggests the use of these nanofluids in direct absorption solar collectors. In conclusion, the present work demonstrates the feasibility of using nanofluids based on transition metal dichalcogenide nanostructures as heat transfer fluids in concentrating solar power plants based on parabolic trough collectors.","En las últimas décadas, el interés en torno a las energías renovables ha aumentado considerablemente debido a la creciente demanda energética y a los problemas medioambientales derivados de la combustión de combustibles fósiles. En este escenario, la energía solar de concentración (CSP) es una energía renovable con un alto potencial para cubrir la demanda energética mundial. Sin embargo, es necesario trabajar para mejorar la eficiencia y reducir el coste de las tecnologías basadas en este tipo de energía con el objetivo de hacerla más competitiva. Una de las líneas de investigación actuales es la sustitución del fluido caloportador utilizado en el tubo absorbedor de los colectores cilindroparabólicos por suspensiones nanocoloidales de nanomateriales en un fluido base, típicamente denominados nanofluidos. Los nanofluidos se consideran una nueva generación de fluidos de transferencia de calor, ya que presentan mejoras en sus propiedades termofísicas en comparación con los fluidos de transferencia de calor convencionales. Pero aún quedan algunos obstáculos por superar para la aplicación de los nanofluidos. Por ejemplo, obtener nanofluidos con alta estabilidad es un reto prioritario en este tipo de sistemas. También garantizar que las nanopartículas no obstruyan las tuberías ni provoquen caídas de presión. En esta Tesis Doctoral se ha investigado por primera vez el uso de nanofluidos basados en dicalcogenuros de metales de transición como fluido caloportador en centrales solares. En concreto, se han investigado nanofluidos basados en nanoestructuras unidimensionales, bidimensionales y tridimensionales de MoS2, WS2 y WSe2. El fluido base utilizado en la preparación de estos nanofluidos es la mezcla eutéctica de bifenilo y óxido de difenilo empleada habitualmente como fluido de transferencia de calor en las centrales de concentración de energía solar. Se han explorado principalmente dos métodos de preparación: el método de exfoliación en fase líquida y la síntesis solvotermal del nanomaterial y su posterior dispersión en el aceite térmico mediante ultrasonidos. También se han analizado parámetros experimentales como la concentración de surfactante, el tiempo y la frecuencia de sonicación para la preparación de los nanofluidos. Los nanofluidos han sido sometidos a una extensa caracterización que incluye el estudio de la estabilidad coloidal a lo largo del tiempo, la caracterización de propiedades térmicas como el calor específico isobárico o la conductividad térmica, propiedades reológicas y propiedades ópticas. Los resultados han revelado que los nanofluidos basados en nanoestructuras 1D y 2D de dicalcogenuros de metales de transición son coloidalmente estables en el tiempo y presentan propiedades térmicas mejoradas en comparación con el fluido térmico típico utilizado en las centrales solares. Los nanofluidos más prometedores son los basados en nanoláminas de MoS2 y los basados en nanoláminas de WSe2, con mejoras del coeficiente de transferencia térmica del 36,2% y el 34,1%, respectivamente, con respecto al aceite térmico. Además, el espectacular papel de las nanoláminas de WSe2 en la mejora de la extinción óptica del aceite térmico sugiere el uso de estos nanofluidos en colectores solares de absorción directa. En conclusión, el presente trabajo demuestra la viabilidad del uso de nanofluidos basados en nanoestructuras de dicalcogenuros de metales de transición como fluidos de transferencia de calor en centrales solares de concentración basadas en colectores cilindro-parabólicos."],"dc:format":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/10498/29235"],"dc:language.iso":["eng"],"dc:rights":["Attribution-NonCommercial-NoDerivatives 4.0 Internacional"],"dc:rights.uri":["http://creativecommons.org/licenses/by-nc-nd/4.0/"],"dc:subject":["concentrating solar power","nanofluids","transition metal dichalcogenide","energía solar de concentración","nanofluidos","dicalcogenuros de metales de transición"],"dc:title":["Nanofluids with optimised thermal properties based on metal chalcogenides with different morphology"],"dc:type":["doctoral thesis"]},"updated_at":"2026-07-24T01:29:44Z"}