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Sonia Fereres
Abengoa Energy Company, Seville, Spain

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Original article
Published: 30 August 2021 in Emergent Materials
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This paper presents experimental results on the study of the effects of ejector adiabatic absorber on heat and mass transfer of binary nanofluid with heat transfer additives (2-ethyl-1-hexanol and gum Arabic). In this case, H2O/lithium bromide-alumina nanofluid was suggested due to a growing interest in absorption heat transfer working fluid for solar energy application. An experimental setup — ejector test rig — was designed to study the absorption, heat, and mass transfer rate as a result of refrigerant vapour mass flow entrained by the ejector adiabatic absorber. The study was carried out at different solution mass flowrate (0.051 to 0.17 kg/s) with three prepared sample solutions, which include pure LiBr solution, LiBr-Alumina nanofluid without heat transfer additives, and LiBr-Alumina nanofluid with heat transfer additives. The absorption rate, mass transfer coefficient, heat transfer rate, and heat transfer coefficient for the three samples were reported. On the other hand, the percentage enhancements for all the parameters — at a suitable flow rate of 0.085 kg/s — due to the addition of alumina without and with heat transfer additives were recorded. The absorption rate enhancements were 25% and 96%, the enhancement rates of mass transfer coefficient recorded were 20% and 82%, the heat transfer rate enhancements were 85% and 183%, and the heat transfer coefficient enhancements obtained were 72% and 156% with addition of alumina nanoparticles only and alumina nanoparticles with heat transfer additives respectively. Material mass balance analysis suggests that mass inflow in the ejector equals to the mass outflow from the ejector, indicating a complete absorption of the entrained refrigerant vapour beyond which falling film absorption can occur due to concentration. This article also presents experimental evidence of the capability of ejector as strong adiabatic absorber, heat, and mass transfer component, which were earlier reported using numerical models.

ACS Style

Umar Aliyu Muhammad; Debabratta Bhattacharyya; Jose Louis Endrino; Sonia Fereres. The effects of ejector adiabatic absorber on heat and mass transfer of binary nanofluid with heat transfer additives. Emergent Materials 2021, 1 -14.

AMA Style

Umar Aliyu Muhammad, Debabratta Bhattacharyya, Jose Louis Endrino, Sonia Fereres. The effects of ejector adiabatic absorber on heat and mass transfer of binary nanofluid with heat transfer additives. Emergent Materials. 2021; ():1-14.

Chicago/Turabian Style

Umar Aliyu Muhammad; Debabratta Bhattacharyya; Jose Louis Endrino; Sonia Fereres. 2021. "The effects of ejector adiabatic absorber on heat and mass transfer of binary nanofluid with heat transfer additives." Emergent Materials , no. : 1-14.

Original article
Published: 06 August 2021 in Emergent Materials
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Current binary nanofluid synthesis methods with heat transfer additives lack an understanding of the chemistry of the nanoparticle-additive-base fluid interaction, which plays a significant role in the adsorption of the surfactant on the nanoparticle surface. Consequently, this leads to the formation of aggregates within the nanofluid after a couple of days, affecting the stability of the colloidal suspension. Here, a lithium bromide-alumina salt-based nanofluid is proposed following a newly developed synthesis method including particle surface functionalisation. The new procedure developed allows the initial preparation of the nanoparticles with the surfactant as the first step (surface functionalisation) and then the preparation of the base fluid with a dispersion stabilising agent (Gum Arabic) separately. This is then followed by the dispersion of the prepared alumina nanoparticles into the base fluid, by stirring and ultrasonication to produce the final nanofluid, lithium bromide-water (LiBr-H2O)-alumina nanofluid. Until now, proper procedures have not been reported for the nanofluid synthesis combining surfactant and dispersant and the chemistry of nanoparticles-surfactant-base fluid interaction, which was thoroughly investigated in the new approach. The fluid prepared by both the conventional and new procedures was characterised and analysed simultaneously. A thermal conductivity enhancement of 3% was achieved by using the surface functionalisation method, with greater particle concentration distribution (number of particles in suspension) of 22.7% over the conventional procedure. It also achieved a 5% decrease in dynamic viscosity. On the other hand, a Mouromtseff number value between 0.7 and 1.8 was obtained for the fluid at 293 K and 373 K temperature range, indicating a strong heat transfer capability. It was apparent from the particle size and concentration distribution analysis conducted that this procedure produced a more stable nanofluid with a high distribution of nanoparticles within the fluid. This allows high improvement of thermal properties of the fluid. Graphical abstract Graphical abstract of a new procedure for nanofluid synthesis with heat transfer additives using the two-step method

ACS Style

Umar Aliyu Muhammad; Debabratta Bhattacharyya; Jose Louis Endrino; Sonia Fereres. Preparation of binary nanofluid with heat transfer additives by particle surface functionalisation. Emergent Materials 2021, 1 -16.

AMA Style

Umar Aliyu Muhammad, Debabratta Bhattacharyya, Jose Louis Endrino, Sonia Fereres. Preparation of binary nanofluid with heat transfer additives by particle surface functionalisation. Emergent Materials. 2021; ():1-16.

Chicago/Turabian Style

Umar Aliyu Muhammad; Debabratta Bhattacharyya; Jose Louis Endrino; Sonia Fereres. 2021. "Preparation of binary nanofluid with heat transfer additives by particle surface functionalisation." Emergent Materials , no. : 1-16.

Journal article
Published: 28 June 2021 in Energies
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Steam accumulation is one of the most effective ways of thermal energy storage (TES) for the solar thermal energy (STE) industry. However, the steam accumulator concept is penalized by a bad relationship between the volume and the energy stored; moreover, its discharge process shows a decline in pressure, failing to reach nominal conditions in the turbine. From the economic point of view, between 60% and 70% of the cost of a steam accumulator TES is that of the pressure vessel tanks (defined as US$/kWhth). Since the current trend is based on increasing hours of storage in order to improve dispatchability levels in solar plants, the possibility of cost reduction is directly related to the cost of the material of pressure vessels, which is a market price. Therefore, in the present paper, a new design for steam accumulation is presented, focusing on innovative materials developed specifically for this purpose: two special concretes that compose the accumulation tank wall. Study of dosages, selection of materials and, finally, scale up on-field tests for their proper integration, fabrication and construction in prototype are the pillars of this new steam accumulation tank. Establishing clear and precise requirements and instructions for successful tank construction is necessary due to the highly sensitive and variable nature of those new concrete formulations.

ACS Style

Cristina Prieto; David Pérez Osorio; Edouard Gonzalez-Roubaud; Sonia Fereres; Luisa Cabeza. Advanced Concrete Steam Accumulation Tanks for Energy Storage for Solar Thermal Electricity. Energies 2021, 14, 3896 .

AMA Style

Cristina Prieto, David Pérez Osorio, Edouard Gonzalez-Roubaud, Sonia Fereres, Luisa Cabeza. Advanced Concrete Steam Accumulation Tanks for Energy Storage for Solar Thermal Electricity. Energies. 2021; 14 (13):3896.

Chicago/Turabian Style

Cristina Prieto; David Pérez Osorio; Edouard Gonzalez-Roubaud; Sonia Fereres; Luisa Cabeza. 2021. "Advanced Concrete Steam Accumulation Tanks for Energy Storage for Solar Thermal Electricity." Energies 14, no. 13: 3896.

Journal article
Published: 08 June 2020 in Energies
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Industries with fast-developing technologies and knowledge-intensive business services rely on the development of scientific knowledge for their growth. This is also true in the renewable energy industry such as in concentrating solar power (CSP) plants, which have undergone intense development and expansion in the last two decades. Yet knowledge generation is not sufficient; its dissemination and internalization by the industry is indispensable for new product development. This paper contributes to providing empirical evidence on the known link between knowledge development and firm growth. In 10 years the cost of electricity produced through CSP has decreased five-fold. This decrease has only been possible due to innovation projects developed through a complex network of research and development (R&D) collaborations and intense investment, both public and (to a greater extent) private. The development and construction of pilot plants and demonstration facilities are shown to be key in maturing innovations for commercialization. This is an example of how the private sector is contributing to the decarbonisation of our energy system, contributing to the objectives of climate change mitigation.

ACS Style

Cristina Prieto; Sonia Fereres; Luisa F. Cabeza. The Role of Innovation in Industry Product Deployment: Developing Thermal Energy Storage for Concentrated Solar Power. Energies 2020, 13, 1 .

AMA Style

Cristina Prieto, Sonia Fereres, Luisa F. Cabeza. The Role of Innovation in Industry Product Deployment: Developing Thermal Energy Storage for Concentrated Solar Power. Energies. 2020; 13 (11):1.

Chicago/Turabian Style

Cristina Prieto; Sonia Fereres; Luisa F. Cabeza. 2020. "The Role of Innovation in Industry Product Deployment: Developing Thermal Energy Storage for Concentrated Solar Power." Energies 13, no. 11: 1.

Journal article
Published: 14 March 2020 in Journal of Molecular Liquids
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Binary alkali nitrate molten salts are currently the heat transfer fluid (HTF) and thermal energy storage (TES) media of choice in commercial solar thermal energy (STE) power plants. This paper studies the rheological properties of binary alkali nitrate molten salts containing two distinct classes of suspended particles with unique practical applications and dynamics. Phase change salt slurries (liquid/solid suspensions) can appear during plant start-up after local freezing in pipes. Molten salt-nanoparticle suspensions are being proposed in the literature as an advanced HTF with enhanced properties. The phase change slurries were analyzed by rheological measurement of off-eutectic salt mixtures at sub-liquidus temperatures combined with determination of solid fraction through differential scanning calorimeter (DSC) testing in a novel approach. Molten salts with a range of silica nanoparticle loadings were also studied in the rheometer. Both suspension types exhibit non-Newtonian, shear thinning behavior, with a dramatic increase in viscosity compared to the base fluid. Additionally, both suspension types show that measured viscosity depends on the shear history, but the trends in viscosity with shear history differs between the two systems. The increase in viscosity with solid volume fraction of the nanofluid is significantly higher than that of a partially-crystallized salt slurry at a given volume fraction. Particle aggregation, particle/cluster aspect ratio, cluster breakage and restructuring are considered as determining factors in the observed rheological behavior. Deviations from classical effective medium theories of well-dispersed systems are discussed. Differing trends suggest that unique physical phenomena govern the rheological behaviors of the molten salt mixtures with different suspended solid particles. Thus, engineers and scientists must exercise caution when extrapolating rheological results to unique applications.

ACS Style

Anthony C. DeFilippo; Mauricio Zurita-Gotor; Melanie Durth; Sonia Fereres. Rheological analysis of nitrate molten salts with suspended particles for solar thermal plants. Journal of Molecular Liquids 2020, 306, 112903 .

AMA Style

Anthony C. DeFilippo, Mauricio Zurita-Gotor, Melanie Durth, Sonia Fereres. Rheological analysis of nitrate molten salts with suspended particles for solar thermal plants. Journal of Molecular Liquids. 2020; 306 ():112903.

Chicago/Turabian Style

Anthony C. DeFilippo; Mauricio Zurita-Gotor; Melanie Durth; Sonia Fereres. 2020. "Rheological analysis of nitrate molten salts with suspended particles for solar thermal plants." Journal of Molecular Liquids 306, no. : 112903.

Journal article
Published: 07 February 2020 in Acta Astronautica
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Fifty years after the first human step on the Moon, many challenges for its exploration have yet to be overcome. Among them, the survival of the crew and/or lunar assets during the lunar night is mandatory for long duration missions. The environmental conditions of the lunar surface and its day-night cycle, with long periods of darkness, make the provision of energy a critical challenge. Several approaches have recently been considered to store and provide energy in the surface of the Moon by means of ISRU (In-Situ Resource Utilisation). We present a trade-off analysis of the options identified for an ISRU-based system to store heat and generate electricity for lunar missions with both robotic and human activities. A critical review of the energy requirements for a mission scenario consisting of long duration stays on the lunar surface has been carried out. Technologies potentially suitable for system components have been identified. These technologies are related to solar energy collection, heat transport, heat storage, heat-to-electricity conversion, and heat rejection. The outcome of the trade-off analysis provides a selection of the most suitable technologies to use in an ISRU-based heat storage and electricity generation system.

ACS Style

Mario F. Palos; Pol Serra; Sonia Fereres; Keith Stephenson; Ricard González-Cinca. Lunar ISRU energy storage and electricity generation. Acta Astronautica 2020, 170, 412 -420.

AMA Style

Mario F. Palos, Pol Serra, Sonia Fereres, Keith Stephenson, Ricard González-Cinca. Lunar ISRU energy storage and electricity generation. Acta Astronautica. 2020; 170 ():412-420.

Chicago/Turabian Style

Mario F. Palos; Pol Serra; Sonia Fereres; Keith Stephenson; Ricard González-Cinca. 2020. "Lunar ISRU energy storage and electricity generation." Acta Astronautica 170, no. : 412-420.

Journal article
Published: 20 November 2019 in Renewable Energy
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Concentrated solar power (CSP) is not currently cost competitive with conventional power generation or other solar energy technologies, but it is attractive because it integrates commercially viable large-scale thermal energy storage (TES). To improve performance and reduce costs, supercritical carbon dioxide (s-CO2) power cycles have been proposed to increase the thermal-to-electric conversion to values above 50%. However, to achieve this target, the solar energy collected by the receiver and stored in the TES must be delivered to the power turbine at a temperature at or above 700 °C, while current advanced plants only provide thermal energy at 565 °C. For the first time, a high temperature (700 °C) molten salt experimental pilot plant for CSP was designed, built, and tested by Abengoa using carbonate salts as the heat transfer fluid. We demonstrate the feasibility of large-scale, industrially relevant operation between 400 and 700 °C, thus providing a solution to integrate higher efficiency s-CO2 power cycles. We address the key points in material compatibility, component design, instrumentation and system integration. Operational aspects such as preheating and filling procedures, start-up, maximum temperature reached, and the main challenges faced are described in detail. The heat losses in the loop and components are analyzed. We show that with appropriate electrical heat tracing elements, operation with carbonates is feasible and that the main subsystems that must be redesigned are the high temperature tanks and pumps. Lessons learned from the plant operation are summarized here to guide the design of future commercial scale high temperature molten salt plants.

ACS Style

Cristina Prieto; Sonia Fereres; Francisco Javier Ruiz-Cabañas; Alfonso Rodriguez-Sanchez; Cristina Montero. Carbonate molten salt solar thermal pilot facility: Plant design, commissioning and operation up to 700 °C. Renewable Energy 2019, 151, 528 -541.

AMA Style

Cristina Prieto, Sonia Fereres, Francisco Javier Ruiz-Cabañas, Alfonso Rodriguez-Sanchez, Cristina Montero. Carbonate molten salt solar thermal pilot facility: Plant design, commissioning and operation up to 700 °C. Renewable Energy. 2019; 151 ():528-541.

Chicago/Turabian Style

Cristina Prieto; Sonia Fereres; Francisco Javier Ruiz-Cabañas; Alfonso Rodriguez-Sanchez; Cristina Montero. 2019. "Carbonate molten salt solar thermal pilot facility: Plant design, commissioning and operation up to 700 °C." Renewable Energy 151, no. : 528-541.

Conference paper
Published: 01 September 2019 in 2019 European Space Power Conference (ESPC)
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In-Situ Resource Utilization (ISRU) technologies for future deep-space exploration is a current hot topic considering planned lunar missions for the coming years. Energy generation and storage using regolith can be useful not only for future lunar human outposts but also to assist lunar mining or construction activities during the lunar night. Here we explore the design of a packed bed Thermal Energy Storage (TES) system using regolith as the storage media through a numerical model. System requirements are analyzed depending on landing sites and mission needs. Different heat transfer fluids (HTF) are evaluated for the TES charge/discharge, using media available from other complementary ISRU processes (i.e. oxygen/water production from lunar regolith) or gases indispensable for life support systems. Raw regolith of varied composition, several Earth materials and processed/reduced regolith are compared, and different TES integration options are discussed.

ACS Style

Sonia Fereres; Sergio Escario; Cristina Prieto; Sonia De La Rosa. Regolith Packed Bed Thermal Energy Storage for Lunar Night Survival. 2019 European Space Power Conference (ESPC) 2019, 1 -7.

AMA Style

Sonia Fereres, Sergio Escario, Cristina Prieto, Sonia De La Rosa. Regolith Packed Bed Thermal Energy Storage for Lunar Night Survival. 2019 European Space Power Conference (ESPC). 2019; ():1-7.

Chicago/Turabian Style

Sonia Fereres; Sergio Escario; Cristina Prieto; Sonia De La Rosa. 2019. "Regolith Packed Bed Thermal Energy Storage for Lunar Night Survival." 2019 European Space Power Conference (ESPC) , no. : 1-7.

Journal article
Published: 05 September 2018 in Solar Energy Materials and Solar Cells
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The eutectic mixture Li2CO3-Na2CO3-K2CO3 is investigated as a high temperature heat transfer fluid and storage medium alternative for molten salt solar thermal power plants. This salt has an operating temperature range of 400–700 °C, enabling the use of higher temperature/efficiency power cycles. However, this carbonate mixture is known to thermally decompose in air. This study evaluates the thermal stability of the salt mixture under different cover gases: air, nitrogen, carbon dioxide, and an 80/20 carbon dioxide/air mixture. Initial characterization is performed through thermogravimetric analysis (TGA), followed by larger scale testing in a custom-made reactor to simulate conditions closer to its practical use. The results show improved thermal stability with a CO2 atmosphere. The decomposition kinetics under different cover gases are estimated from TGA data. However, larger-scale, longer duration experiments show much slower decomposition rates compared to the classical TGA approach. These findings indicate that the main contribution to mass loss in TGA is due to vaporization rather than thermal decomposition. Thus, a proper evaluation of the molten salt´s thermal stability can only be obtained from reactor experiments where vaporization is inhibited. Very long induction periods (of the order of days) are observed, suggesting that the kinetic decomposition mechanism is a nucleation and growth type. Other considerations for future plants incorporating these high temperature salts are discussed.

ACS Style

Sonia Fereres; Cristina Prieto; Pablo Giménez Gavarrell; Alfonso Rodríguez; Pedro Enrique Sánchez-Jiménez; Luis A Perez-Maqueda. Molten carbonate salts for advanced solar thermal energy power plants: Cover gas effect on fluid thermal stability. Solar Energy Materials and Solar Cells 2018, 188, 119 -126.

AMA Style

Sonia Fereres, Cristina Prieto, Pablo Giménez Gavarrell, Alfonso Rodríguez, Pedro Enrique Sánchez-Jiménez, Luis A Perez-Maqueda. Molten carbonate salts for advanced solar thermal energy power plants: Cover gas effect on fluid thermal stability. Solar Energy Materials and Solar Cells. 2018; 188 ():119-126.

Chicago/Turabian Style

Sonia Fereres; Cristina Prieto; Pablo Giménez Gavarrell; Alfonso Rodríguez; Pedro Enrique Sánchez-Jiménez; Luis A Perez-Maqueda. 2018. "Molten carbonate salts for advanced solar thermal energy power plants: Cover gas effect on fluid thermal stability." Solar Energy Materials and Solar Cells 188, no. : 119-126.

Journal article
Published: 30 March 2018 in Journal of Energy Storage
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ACS Style

Elliott Baché; Cedric Le Bot; Elena Palomo Del Barrio; Sonia Fereres. Effect of domain subdivisions on alloy solidification. Journal of Energy Storage 2018, 17, 228 -238.

AMA Style

Elliott Baché, Cedric Le Bot, Elena Palomo Del Barrio, Sonia Fereres. Effect of domain subdivisions on alloy solidification. Journal of Energy Storage. 2018; 17 ():228-238.

Chicago/Turabian Style

Elliott Baché; Cedric Le Bot; Elena Palomo Del Barrio; Sonia Fereres. 2018. "Effect of domain subdivisions on alloy solidification." Journal of Energy Storage 17, no. : 228-238.

Journal article
Published: 01 July 2017 in Renewable Energy
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ACS Style

Pablo Giménez Gavarrell; Sonia Fereres. Glass encapsulated phase change materials for high temperature thermal energy storage. Renewable Energy 2017, 107, 497 -507.

AMA Style

Pablo Giménez Gavarrell, Sonia Fereres. Glass encapsulated phase change materials for high temperature thermal energy storage. Renewable Energy. 2017; 107 ():497-507.

Chicago/Turabian Style

Pablo Giménez Gavarrell; Sonia Fereres. 2017. "Glass encapsulated phase change materials for high temperature thermal energy storage." Renewable Energy 107, no. : 497-507.

Journal article
Published: 01 June 2017 in Renewable Energy
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ACS Style

P. Giménez; A. Jové; Cristina Prieto; Sonia Fereres. Effect of an increased thermal contact resistance in a salt PCM-graphite foam composite TES system. Renewable Energy 2017, 106, 321 -334.

AMA Style

P. Giménez, A. Jové, Cristina Prieto, Sonia Fereres. Effect of an increased thermal contact resistance in a salt PCM-graphite foam composite TES system. Renewable Energy. 2017; 106 ():321-334.

Chicago/Turabian Style

P. Giménez; A. Jové; Cristina Prieto; Sonia Fereres. 2017. "Effect of an increased thermal contact resistance in a salt PCM-graphite foam composite TES system." Renewable Energy 106, no. : 321-334.

Proceedings article
Published: 13 November 2015 in Volume 3: Biomedical and Biotechnology Engineering
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Combining latent and sensible heat storage within a single material has lead researchers to propose off-eutectic salt mixtures for solar thermal energy storage. A binary salt mixture with an off-eutectic composition presents a melting temperature range as opposed to a melting point, providing additional storage capacity through the sensible heat present during the melting/solidification. However, some drawbacks of off-eutectic mixtures include a higher propensity towards incongruous melting, phase segregation of the mixture upon solidification, and thermal cycling issues. Here the solid-liquid transitions of a series of eutectic and off-eutectic KNO3-NaNO3 mixtures are evaluated to determine if the addition of nanoparticles can limit phase segregation yet still present good thermal properties. Measurements performed with a Differential Scanning Calorimeter show that the effect of nanoparticles is unimportant compared to the difference between eutectic and off-eutectic phase change behavior. Onset temperatures, latent heats, and the width of the phase transition temperature trace during melting/solidification are compared for the eutectic and off-eutectic salt mixtures with and without silica nanoparticles. A reduction in the latent heat is observed and explained through classical mixing theory. The modification of the phase change properties of eutectic and off-eutectic nanofluids are discussed.

ACS Style

Pau Gimenez-Gavarrell; Sonia Fereres. An Experimental Study of the Effect of SiO2 Nanoparticles on the Phase Change Characteristics of KNO3-NaNO3 Mixtures for Thermal Energy Storage. Volume 3: Biomedical and Biotechnology Engineering 2015, 1 .

AMA Style

Pau Gimenez-Gavarrell, Sonia Fereres. An Experimental Study of the Effect of SiO2 Nanoparticles on the Phase Change Characteristics of KNO3-NaNO3 Mixtures for Thermal Energy Storage. Volume 3: Biomedical and Biotechnology Engineering. 2015; ():1.

Chicago/Turabian Style

Pau Gimenez-Gavarrell; Sonia Fereres. 2015. "An Experimental Study of the Effect of SiO2 Nanoparticles on the Phase Change Characteristics of KNO3-NaNO3 Mixtures for Thermal Energy Storage." Volume 3: Biomedical and Biotechnology Engineering , no. : 1.

Proceedings article
Published: 28 June 2015 in Volume 2: Photovoltaics; Renewable-Non-Renewable Hybrid Power System; Smart Grid, Micro-Grid Concepts; Energy Storage; Solar Chemistry; Solar Heating and Cooling; Sustainable Cities and Communities, Transportation; Symposium on Integrated/Sustainable Building Equipment and Systems; Thermofluid Analysis of Energy Systems Including Exergy and Thermoeconomics; Wind Energy Systems and Technologies
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Thermal Energy Storage (TES) can improve the efficient and economical use of available resources associated with renewable energies. The choice of Phase Change Materials (PCM) for TES applications is particularly attractive, since PCMs provide high energy storage densities, low costs, and allow energy storage at constant temperatures during the melting/solidification process. However, most commonly used PCMs have low thermal conductivity values, typically less than 1 W/mK. This leads to insufficient heat exchange rates in many applications, where power is as important as the amount of energy stored. Previous studies have shown that adding nanoparticles to molten salts can enhance the thermal conductivity and heat capacity, thus improving performance in TES systems. This study analyzes how adding nanoparticles to ionic liquids/solids affects the latent heat of fusion and melting temperature, critical characteristics of many thermal management systems. An important aspect of nanoparticle suspension preparation is the synthesis method, both from the point of view of scalability and effect on thermophysical properties. Several nanoparticle suspensions are synthesized with carbon nanotubes (CNT) and salt or ionic liquid base materials, using different synthesis methods and sonication times. The melting point and latent heat of fusion are measured for the base materials and nanoparticle suspensions using a Differential Scanning Calorimeter (DSC). The change in latent heat and melting temperature of the nanofluid with respect to the base fluid is shown to be present but not substantial. Possible explanations for the modification of thermal properties with respect to the base fluid are discussed.

ACS Style

Pau Gimenez-Gavarrell; Vincent D. Romanin; Sonia Fereres. Latent Heat of Fusion and Melting Temperature of Molten Salt Based Carbon Nanotube Suspensions Used as Phase Change Materials. Volume 2: Photovoltaics; Renewable-Non-Renewable Hybrid Power System; Smart Grid, Micro-Grid Concepts; Energy Storage; Solar Chemistry; Solar Heating and Cooling; Sustainable Cities and Communities, Transportation; Symposium on Integrated/Sustainable Building Equipment and Systems; Thermofluid Analysis of Energy Systems Including Exergy and Thermoeconomics; Wind Energy Systems and Technologies 2015, 1 .

AMA Style

Pau Gimenez-Gavarrell, Vincent D. Romanin, Sonia Fereres. Latent Heat of Fusion and Melting Temperature of Molten Salt Based Carbon Nanotube Suspensions Used as Phase Change Materials. Volume 2: Photovoltaics; Renewable-Non-Renewable Hybrid Power System; Smart Grid, Micro-Grid Concepts; Energy Storage; Solar Chemistry; Solar Heating and Cooling; Sustainable Cities and Communities, Transportation; Symposium on Integrated/Sustainable Building Equipment and Systems; Thermofluid Analysis of Energy Systems Including Exergy and Thermoeconomics; Wind Energy Systems and Technologies. 2015; ():1.

Chicago/Turabian Style

Pau Gimenez-Gavarrell; Vincent D. Romanin; Sonia Fereres. 2015. "Latent Heat of Fusion and Melting Temperature of Molten Salt Based Carbon Nanotube Suspensions Used as Phase Change Materials." Volume 2: Photovoltaics; Renewable-Non-Renewable Hybrid Power System; Smart Grid, Micro-Grid Concepts; Energy Storage; Solar Chemistry; Solar Heating and Cooling; Sustainable Cities and Communities, Transportation; Symposium on Integrated/Sustainable Building Equipment and Systems; Thermofluid Analysis of Energy Systems Including Exergy and Thermoeconomics; Wind Energy Systems and Technologies , no. : 1.

Journal article
Published: 01 May 2015 in Energy Procedia
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A detailed analysis on the thermal degradation of nitrate based molten salts evaluating the influence of different impurities and heating rates in their maximum working temperature is presented. Determining the maximum operating temperature is of interest when searching for new heat transfer fluids (HTF) for high temperature solar thermal applications as it limits the thermodynamic efficiency of the power block. Thermogravimetric analysis is performed on potassium nitrate, sodium nitrate, sodium nitrite, the binary system Solar Salt, and the ternary Hitec. The kinetics of the thermal decomposition reactions are investigated through iso-conversional analysis. The effect of adding some common impurities such us NaCl and Na2CO3 on the multi-component nitrate salts is evaluated. It was found that impurities such as Na2CO3 can enhance the thermal stability of Hitec salt, leading to higher thermal decomposition temperatures. For solar salt, impurities such as NaCl can enhance the thermal stability of solar salt at 10K·min-1, while adding Na2CO3 can have the opposite effect. For nitrate based molten salts used in TES and HTF systems in CSP a reduction on the purity required for the materials can present some operational advantages besides cost reduction

ACS Style

P. Gimenez; S. Fereres. Effect of Heating Rates and Composition on the Thermal Decomposition of Nitrate Based Molten Salts. Energy Procedia 2015, 69, 654 -662.

AMA Style

P. Gimenez, S. Fereres. Effect of Heating Rates and Composition on the Thermal Decomposition of Nitrate Based Molten Salts. Energy Procedia. 2015; 69 ():654-662.

Chicago/Turabian Style

P. Gimenez; S. Fereres. 2015. "Effect of Heating Rates and Composition on the Thermal Decomposition of Nitrate Based Molten Salts." Energy Procedia 69, no. : 654-662.

Journal article
Published: 01 April 2015 in Combustion and Flame
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ACS Style

Sonia Fereres; Carlos Fernandez-Pello; David L. Urban; Gary A. Ruff. Identifying the roles of reduced gravity and pressure on the piloted ignition of solid combustibles. Combustion and Flame 2015, 162, 1136 -1143.

AMA Style

Sonia Fereres, Carlos Fernandez-Pello, David L. Urban, Gary A. Ruff. Identifying the roles of reduced gravity and pressure on the piloted ignition of solid combustibles. Combustion and Flame. 2015; 162 (4):1136-1143.

Chicago/Turabian Style

Sonia Fereres; Carlos Fernandez-Pello; David L. Urban; Gary A. Ruff. 2015. "Identifying the roles of reduced gravity and pressure on the piloted ignition of solid combustibles." Combustion and Flame 162, no. 4: 1136-1143.

Original articles
Published: 10 December 2014 in Combustion Science and Technology
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Wildland and wildland/urban interface fires are a serious problem in many areas of the world. It is expected that with global warming the wildfire and wildland/urban interface fire problem will only intensify. The ignition of natural combustible material by hot metal particles or embers is an important fire ignition pathway by which wildland and urban spot fires are started. There are numerous cases reported of wild fires started by hot metal particles from clashing power lines, or from sparks generated by machines or engines. Similarly there are many cases reported of industrial fires caused by grinding and welding sparks. Despite the importance of the subject, the topic remains relatively unstudied. The senior author of this article and his collaborators have been working for the past few years on this problem. In this article, we provide a comprehensive summary of that work to date. The work includes experimental and theoretical modeling of the ability of hot metal particles and embers to cause the ignition of cellulosic fuel beds. The metal particles studied are representative of clashing conductors (aluminum and copper) and those produced by machine friction and hot work such as welding (stainless steel and brass). In addition glowing and flaming wood embers are considered, as they represent an important source of fire spotting in wildfires. The overall results show a hyperbolic relationship between particle size and temperature, with the larger particles requiring lower temperature to ignite the fuel bed than the smaller particles. An important finding is that although particle energy is important in the capability of the particle to ignite the fuel, both energy and temperature are determining factors of the particle ignition capabilities. The thermal properties of the metal play a lesser role with the exception of the energy of melting if it occurs. It also appears that the controlling ignition mechanisms by large particles are different than those from the small particles. The former appear to be determined primarily by the particle surface temperature while the latter by the particle energy and surface temperature. Sparks are a specific type of particles with very small sizes and very high temperatures. Because of the small sizes, their energy is small and it is postulated that the sparks must accumulate for ignition of a fuel bed to occur. The results with embers indicate that the smoldering is the easier form of ignition, although flaming ignition can occur if the ember is flaming and the air velocities are moderate. To provide further information about the fire spot ignition process, both analytical and numerical modeling are used and compared with the experimental results. Although the models provide qualitative predictions further development is necessary to reach quantitative predictive capabilities.

ACS Style

A. C. Fernandez-Pello; C. Lautenberger; D. Rich; C. Zak; J. Urban; R. Hadden; S. Scott; Sonia Fereres. Spot Fire Ignition of Natural Fuel Beds by Hot Metal Particles, Embers, and Sparks. Combustion Science and Technology 2014, 187, 269 -295.

AMA Style

A. C. Fernandez-Pello, C. Lautenberger, D. Rich, C. Zak, J. Urban, R. Hadden, S. Scott, Sonia Fereres. Spot Fire Ignition of Natural Fuel Beds by Hot Metal Particles, Embers, and Sparks. Combustion Science and Technology. 2014; 187 (1-2):269-295.

Chicago/Turabian Style

A. C. Fernandez-Pello; C. Lautenberger; D. Rich; C. Zak; J. Urban; R. Hadden; S. Scott; Sonia Fereres. 2014. "Spot Fire Ignition of Natural Fuel Beds by Hot Metal Particles, Embers, and Sparks." Combustion Science and Technology 187, no. 1-2: 269-295.

Proceedings article
Published: 14 November 2014 in Volume 2A: Advanced Manufacturing
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Organic Rankine Cycles (ORCs) are primarily used in low-temperature/low-grade heat recovery systems, where water cycles are not efficient enough to economically extract work. For this reason, ORC analysis and ORC fluids have focused on low (< 300 °C) temperatures. Because the Carnot efficiency of a Rankine cycle increases with temperature, the high temperature limit of organic fluids is of interest for exploring the boundary between the economic advantages of organic fluids versus water in Rankine cycles. In this study, the high temperature limit of working fluids and the role of fluid properties on cycle efficiency for critical/subcritical ORCs are investigated. The performance of a wide range of organic fluids is evaluated through the development of thermal property calculator coded in MATLAB using the Peng-Robinson Equation of State (PREOS) and the Design Institute for Physical PRoperties (DIPPR) database correlations for heat capacity. This process allows for the development of an efficient property calculator that allows the rapid characterization of the thermodynamic performance of a large number of working fluids. A regenerative Rankine cycle for organic fluids was compared to a reheated Rankine cycle for water, for temperatures between 100 and 800 °C, with different cycle boundary conditions. The role of working fluid properties such as boiling temperature, critical point, molecular weight, and acentric factor on cycle performance are evaluated. It was found that the limits of efficiency of most of the fluids analyzed results from the limits of the high and low temperature of the cycle. Efficiency improvements due to a combined cycle with two ORCs are also examined. Finally, given the limits and performance of the fluids analyzed, desirable fluid properties for efficient high temperature ORCs are discussed.

ACS Style

Vincent D. Romanin; Alfonso Rodriguez; Jean Toutain; Sonia Fereres. Using the Peng-Robinson Equation of State to Explore Working Fluids for Higher Temperature Organic Rankine Cycles. Volume 2A: Advanced Manufacturing 2014, 1 .

AMA Style

Vincent D. Romanin, Alfonso Rodriguez, Jean Toutain, Sonia Fereres. Using the Peng-Robinson Equation of State to Explore Working Fluids for Higher Temperature Organic Rankine Cycles. Volume 2A: Advanced Manufacturing. 2014; ():1.

Chicago/Turabian Style

Vincent D. Romanin; Alfonso Rodriguez; Jean Toutain; Sonia Fereres. 2014. "Using the Peng-Robinson Equation of State to Explore Working Fluids for Higher Temperature Organic Rankine Cycles." Volume 2A: Advanced Manufacturing , no. : 1.

Review
Published: 14 November 2014 in Volume 2A: Advanced Manufacturing
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The ability to engineer enhanced thermal properties by adding small amounts of nanoparticles to liquids is especially attractive in the case of heat transfer fluids, which find applications in many types of power and heat generation. The specific heat capacity of nanofluids is an important parameter in the design of these systems, especially in the case of thermal energy storage. As with many nanofluid properties, the nature and extent of the modification of the specific heat capacity with the addition of nanoparticles is not well established, and many publications report conflicting experimental data. In contrast to thermal conductivity enhancements, it is yet unclear whether the specific heat capacity of a nanoparticle suspension can increase with respect to the base fluid value. In order to help determine the magnitude, nature, and theory of specific heat capacity modification with the addition of nanoparticles, published experimental heat capacity data for nanofluids was compiled and analyzed to investigate any trends or biases in the data. The objective of this meta-analysis is twofold: 1) to clarify in what cases an enhancement of specific heat capacity can be expected, and 2) to understand the mechanisms responsible for this behavior. It is hypothesized that reported anomalous specific heat enhancements are related to the ionic nature of the base fluid and, therefore, to particle-fluid interactions. Theories of nanofluid heat capacity are discussed in the context of the compiled data. Other factors are also discussed, including the effect of the heat capacity measurement technique, nanofluid synthesis methods, aggregation and dispersion and the characterization thereof, and the effect of base fluid, nanoparticle size, shape, and material. Finally, recommendations are made for improving the reliability and consistency in synthesizing and characterizing nanofluids and their thermal properties.

ACS Style

Vincent D. Romanin; Sonia Fereres. A Meta-Analysis of the Specific Heat Enhancement of Nanofluids. Volume 2A: Advanced Manufacturing 2014, 1 .

AMA Style

Vincent D. Romanin, Sonia Fereres. A Meta-Analysis of the Specific Heat Enhancement of Nanofluids. Volume 2A: Advanced Manufacturing. 2014; ():1.

Chicago/Turabian Style

Vincent D. Romanin; Sonia Fereres. 2014. "A Meta-Analysis of the Specific Heat Enhancement of Nanofluids." Volume 2A: Advanced Manufacturing , no. : 1.

Journal article
Published: 01 January 2014 in Energy Procedia
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ACS Style

E. Bache; C. Le Bot; Sonia Fereres; E. Palomo. Off-eutectic Binary Salt Finite Volume Method. Energy Procedia 2014, 49, 715 -724.

AMA Style

E. Bache, C. Le Bot, Sonia Fereres, E. Palomo. Off-eutectic Binary Salt Finite Volume Method. Energy Procedia. 2014; 49 ():715-724.

Chicago/Turabian Style

E. Bache; C. Le Bot; Sonia Fereres; E. Palomo. 2014. "Off-eutectic Binary Salt Finite Volume Method." Energy Procedia 49, no. : 715-724.