The Experts below are selected from a list of 1740 Experts worldwide ranked by ideXlab platform
R. Couturier - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of cycling behaviour of pilot scale Thermal Oil packed bed Thermal storage system
Renewable Energy, 2017Co-Authors: Arnaud Bruch, S. Molina, Thibaut Esence, Jeanfrancois Fourmigue, R. CouturierAbstract:Extensive experimental study of dual media thermocline Thermal energy storage using rock and sand as solid matrix and Thermal Oil as heat transfer fluid is presented. The work is devoted to the establishing of repeatable behaviours observed with multiple charge/discharge cycles and to the influences of operating parameters. Experimental results show that established behaviours are independent of most of operating parameters, notably tank initial state, mass flow rate and temperature ranges, and mainly depend on thermocline control strategy, i.e. part of the Thermal gradient which is pulled out of the tank in charge and discharge. Experimental performances have been determined for a large range of control strategies and show tank utilisation rate ranging from about 10% to more than 80%. Thermocline response to perturbations has been studied and shows that partial charge perturbations lead to performances reduction with rapid return to established behaviours. These results may strongly enhance dual media thermocline understanding and may help design and integration of such TES in a given process.
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Experimental and numerical investigation of potential filler materials for Thermal Oil thermocline storage
Solar Energy, 2016Co-Authors: H. Grirate, A. Elmchaouri, S. Molina, H. Agalit, Nadia Zari, R. CouturierAbstract:Abstract A Thermal energy storage system (TES) is a key technology to ensure continuous power supply from solar Thermal power plants. Choosing the appropriate storage method and the suitable material for energy storage remains a major challenge in research and development in the solar power field. The sensible heat storage in solid media using thermocline system is a significant cost-effective option when compared to liquid storage material in two tank system. An incorporation of this potential concept is the Oil/rock thermocline system which is based on the direct contact between natural rocks chosen as filler material and Thermal Oil as the heat transfer fluid (HTF), and it is used in the Concentrated Solar Power (CSP) plants. The present paper highlights the Thermal energy storage potential of six rocks (quartzite, basalt, granite, hornfels, cipolin and marble) proposed as filler material for Thermal Oil thermocline storage concept. These rocks were chosen according to their abundance in Morocco. Different technical methods were performed in order to assess the rocks properties (physical, chemical and Thermal) at temperatures up to 350 °C (temperature operating conditions using linear Fresnel reflectors or parabolic trough). The Thermal performances of the studied rocks inside a thermocline storage system were evaluated using a validated numerical model. Based on the experimental investigation two rocks (Quartzite and Cipolin) were identified as the most suitable filler materials to be used in direct contact with the studied HTF (synthetic Oil). While, the numerical analysis revealed that Basalt rock has the best Thermal performances inside the studied thermocline storage system concept, but it isn’t chemically compatible with synthetic Oil. Hence, it can be used advantageously with other heat transfer medium (e.g. Air).
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Life time analysis of Thermal Oil used as heat transfer fluid in CSP power plant
2016Co-Authors: H. Grirate, N. Zari, A. Elmchaouri, S. Molina, R. CouturierAbstract:The present work describes stability testing of hydrogenated terphenyl (HT), Thermal Oil available in the market and considered as a potential HTF for CSP power plants. Before ageing tests, hydrogenated terphenyl was compared to Biphenyl/diphenyl oxide (DPO) at the initial state, which is the most commonly used HTF in CSP plants (SEGS VI and ANDASOL I) and included as a comparison material in the NREL HTF requirements. The (HT) stability tests were performed in sealed ampoules (stainless steel) under inert gas blanket in the range of temperature between 250°C and 350°C (max temperature of HT) for 500 hrs. After ageing, many investigations were made to track the Thermal Oil behavior after extended time over a range of temperature, such as chemical composition, flash point, viscosity, acid value…. Laboratory testing indicated that the hydrogenated terphenyl (HT) is stable after ageing process at a temperature of about 250°C. Nevertheless, it has shown signs of serious Thermal cracking at elevated temperature which is reflected by low flash point temperature. Therefore, the system must be purged effectively to purge the volatile decomposition products.
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experimental and numerical investigation of a pilot scale Thermal Oil packed bed Thermal storage system for csp power plant
Solar Energy, 2014Co-Authors: Arnaud Bruch, Jeanfrancois Fourmigue, R. CouturierAbstract:Abstract A pilot-scale Oil/rock thermocline Thermal energy storage (TES) system, consisting of a packed bed of two characteristic sizes rocks as storage material and Thermal Oil as heat transfer fluid, is experimentally studied. Exhaustive temperature instrumentation, with more than 250 imbedded thermocouples, shows that no significant inhomogeneity or by-pass exists in the rock bed and that the heat transfer process is mainly one-dimensional. Investigation of multiple charge/discharge cycles exhibits established behaviour quite different from single charge/discharge cycle and directly influenced by operating control of the TES system. A predictive approach of the packed bed pressure drops, based on hydraulic characteristics inside the rock-bed, has been developed and show very good agreement with the experimental measurements. A one dimensional numerical model based on two energy balances has been developed and validated with experimental data for both single and multiple charge/discharge. These experimental and numerical results confirm that dual-media thermocline storage is controllable and predictable and can be used as efficient storage solution for CSP plant.
Marneni Narahari - One of the best experts on this subject based on the ideXlab platform.
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Rheological characteristics of ultrastable diamond-Thermal Oil nanofluids
Journal of Molecular Liquids, 2020Co-Authors: Suhaib Umer Ilyas, Marneni Narahari, Rajashekhar PendyalaAbstract:Abstract Diamond nanoparticles possess numerous industrial applications, especially in the areas of heat transfer, catalysis, advanced materials, medical, electronics, and sensors. The rheological behavior of diamond-based nanosuspensions is experimentally investigated. The dispersions of diamond nanoparticles in highly refined Thermal Oil (THO) with 70–99 wt% hydrocarbons (C15-C50) are prepared at varying particle loadings using two-step technique. Different surface characterizations are performed for the nanoparticles. The investigation is carried out for considerably high diamond nanoparticle loadings in THO, i.e., 0.1 wt% to 1 wt%. A combination of ultrasonication and stabilizer-addition method is applied to obtain ultrastability (four months) for factual applications of nanofluids. The viscosity of diamond-THO nanofluids is measured at varying temperatures and shear rates in the range of 298-338 K and 500–2000s−1, respectively. The obtained results affirm the non-Newtonian and shear thinning character of diamond-THO nanofluids. The shear-thinning behavior is quantified using Ostwald-de-Waele relationship. A maximum increase of 21% in the viscosity is found for 1 wt% diamond nanosuspension at 298 K. The experimental data of viscosities is compared with the VFT (Vogel-Fulcher-Tammann) eq. A generalized multivariable correlation for the viscosity of diamond-THO nanofluid is presented as a function of temperature and nanoparticle loading.
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Experimental investigation of natural convection heat transfer characteristics in MWCNT-Thermal Oil nanofluid
Journal of Thermal Analysis and Calorimetry, 2018Co-Authors: Suhaib Umer Ilyas, Rajashekhar Pendyala, Marneni NarahariAbstract:The carbon nanotubes are considered as one of the highest Thermal conductive material which is having a variety of heat transfer applications. The suitability of carbon nanotubes in convective heat transfer is examined using multi-wall carbon nanotubes (MWCNT)-Thermal Oil-based nanofluids. Stable nanofluids are prepared in the concentration range of 0–1 mass% and Prandtl number range of 415 ≤ Pr ≤ 600 using ultrasonication. The natural convection heat transfer behavior is studied experimentally in a vertical rectangular enclosure with aspect ratio 4. The heat transfer experiments are conducted at varying heat flux in the range of 1594–3150 W m−2. The heat transfer coefficient, Nusselt number and Rayleigh number are estimated for MWCNT-Thermal Oil-based nanofluids and are compared with pure Thermal Oil. A significant deterioration in heat transfer coefficient is observed at higher concentrations of nanofluids. The study signifies the adverse impact on the cooling performance of MWCNT-Thermal Oil-based nanofluids in natural convection heat transfer, even though higher Thermal conductivities are observed in nanofluids. It is found that not only Thermal conductivity is essential property in heat transfer, but other thermophysical properties are also influential towards Thermal management.
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An experimental study on the natural convection heat transfer in rectangular enclosure using functionalized alumina-Thermal Oil-based nanofluids
Applied Thermal Engineering, 2017Co-Authors: Suhaib Umer Ilyas, Rajashekhar Pendyala, Marneni NarahariAbstract:Abstract The nanofluids are considered as an effective medium for Thermal transport in various applications due to improved properties. Limited experimental studies are accomplished on the convective heat transfer of nanofluids. Natural convective heat transfer behavior in nanofluids is experimentally studied in a vertical rectangular enclosure (aspect ratio = 4) with one heating and one cooling wall. The fluid under investigation is a novel and highly stable functionalized alumina-Thermal Oil-based nanofluid. The investigations are carried out for different concentrations of nanofluids ranging from 0 to 3 wt%. The effectiveness of the natural convection heat transfer process is mainly dependent on the properties of cooling media. The measured thermophysical properties of nanofluids are used for the estimation of heat transfer characteristics with a Prandtl number range of 228–592. The heat transfer coefficient and Nusselt number are obtained at different nanoparticle concentrations. A heat flux is applied on the hot wall with a range of 1593.75–3150 W/m 2 . An improvement in the cooling performance of nanofluids is observed. The high nanoparticle concentrations of nanofluids exhibit higher heat transfer coefficient as compared to the pure Thermal Oil. A correlation is developed for the Nusselt number in terms of Rayleigh number (4.43 × 10 5 –2.59 × 10 6 ), nanoparticle concentration and effective thermophysical properties.
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Rheological behavior of mechanically stabilized and surfactant-free MWCNT-Thermal Oil-based nanofluids
International Communications in Heat and Mass Transfer, 2017Co-Authors: Suhaib Umer Ilyas, Rajashekhar Pendyala, Marneni NarahariAbstract:Abstract The viscosity of nanofluids is one of the important parameter for the design of heat transfer processes. The evolution of usage of nanofluids in heat transfer processes is gaining more industrial consideration due to excellent Thermal properties. However, limited attention is focused on the rheological behavior of nanofluids as of today. The multiwall carbon nanotubes (MWCNTs) are stabilized in Thermal Oil using ultrasonication and high stability is observed. The rheological behavior of Thermal-Oil based dispersant-free nanofluids are studied at varying high shear rates (100–2000 s − 1 ), temperatures (25–90 °C) and nanoparticle concentrations (0.1–1 wt%). The effect on the shear stress and viscosity by the addition of carbon nanotubes in Thermal Oil is discussed. The measured effective viscosity is compared with different theoretical conventional models. A significant increment in relative viscosity is observed at high concentrations of carbon nanotubes. A correlation is developed based on the temperature, nanomaterial concentration, and shear rate.
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stability and Thermal analysis of mwcnt Thermal Oil based nanofluids
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2017Co-Authors: Suhaib Umer Ilyas, Rajashekhar Pendyala, Marneni NarahariAbstract:Abstract Carbon nanotubes (CNTs) have gained much attention due to excellent Thermal properties. Numerous studies have reported the incremental Thermal conductivity of CNT-based nanofluids. However, limited studies are available on the complete Thermal and viscous transport effects in Oil-based nanofluids. Multi-wall carbon nanotubes (MWCNTs)-Thermal Oil-based nanofluids are prepared using two-step method. The high stability is achieved using mechanical mixing technique (ultrasonication) only. Surfactant-free nanofluids are prepared in various concentrations of 0–1 wt.%. Dispersion behaviour of nanofluids is investigated to ensure high stability of nanofluids using different characterizations. The effective thermophysical properties such as density, viscosity, Thermal conductivity, and specific heat capacity are experimentally investigated at different temperature ranges and nanoparticle concentrations. The experimental findings of the present work are compared with the theoretical models and good agreement is observed for effective density of nanofluids. However, other thermophysical properties show a significant deviation with the conventional models. The coefficient of Thermal expansion is calculated for Oil-based nanofluids. Correlations are developed for thermophysical properties of nanofluids. Thermogravimetric analysis (TGA) is carried out to understand the effect of nanotubes on the life-cycle and the degradation temperature of Thermal Oil.
Arnaud Bruch - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of cycling behaviour of pilot scale Thermal Oil packed bed Thermal storage system
Renewable Energy, 2017Co-Authors: Arnaud Bruch, S. Molina, Thibaut Esence, Jeanfrancois Fourmigue, R. CouturierAbstract:Extensive experimental study of dual media thermocline Thermal energy storage using rock and sand as solid matrix and Thermal Oil as heat transfer fluid is presented. The work is devoted to the establishing of repeatable behaviours observed with multiple charge/discharge cycles and to the influences of operating parameters. Experimental results show that established behaviours are independent of most of operating parameters, notably tank initial state, mass flow rate and temperature ranges, and mainly depend on thermocline control strategy, i.e. part of the Thermal gradient which is pulled out of the tank in charge and discharge. Experimental performances have been determined for a large range of control strategies and show tank utilisation rate ranging from about 10% to more than 80%. Thermocline response to perturbations has been studied and shows that partial charge perturbations lead to performances reduction with rapid return to established behaviours. These results may strongly enhance dual media thermocline understanding and may help design and integration of such TES in a given process.
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experimental and numerical investigation of a pilot scale Thermal Oil packed bed Thermal storage system for csp power plant
Solar Energy, 2014Co-Authors: Arnaud Bruch, Jeanfrancois Fourmigue, R. CouturierAbstract:Abstract A pilot-scale Oil/rock thermocline Thermal energy storage (TES) system, consisting of a packed bed of two characteristic sizes rocks as storage material and Thermal Oil as heat transfer fluid, is experimentally studied. Exhaustive temperature instrumentation, with more than 250 imbedded thermocouples, shows that no significant inhomogeneity or by-pass exists in the rock bed and that the heat transfer process is mainly one-dimensional. Investigation of multiple charge/discharge cycles exhibits established behaviour quite different from single charge/discharge cycle and directly influenced by operating control of the TES system. A predictive approach of the packed bed pressure drops, based on hydraulic characteristics inside the rock-bed, has been developed and show very good agreement with the experimental measurements. A one dimensional numerical model based on two energy balances has been developed and validated with experimental data for both single and multiple charge/discharge. These experimental and numerical results confirm that dual-media thermocline storage is controllable and predictable and can be used as efficient storage solution for CSP plant.
Suhaib Umer Ilyas - One of the best experts on this subject based on the ideXlab platform.
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Rheological characteristics of ultrastable diamond-Thermal Oil nanofluids
Journal of Molecular Liquids, 2020Co-Authors: Suhaib Umer Ilyas, Marneni Narahari, Rajashekhar PendyalaAbstract:Abstract Diamond nanoparticles possess numerous industrial applications, especially in the areas of heat transfer, catalysis, advanced materials, medical, electronics, and sensors. The rheological behavior of diamond-based nanosuspensions is experimentally investigated. The dispersions of diamond nanoparticles in highly refined Thermal Oil (THO) with 70–99 wt% hydrocarbons (C15-C50) are prepared at varying particle loadings using two-step technique. Different surface characterizations are performed for the nanoparticles. The investigation is carried out for considerably high diamond nanoparticle loadings in THO, i.e., 0.1 wt% to 1 wt%. A combination of ultrasonication and stabilizer-addition method is applied to obtain ultrastability (four months) for factual applications of nanofluids. The viscosity of diamond-THO nanofluids is measured at varying temperatures and shear rates in the range of 298-338 K and 500–2000s−1, respectively. The obtained results affirm the non-Newtonian and shear thinning character of diamond-THO nanofluids. The shear-thinning behavior is quantified using Ostwald-de-Waele relationship. A maximum increase of 21% in the viscosity is found for 1 wt% diamond nanosuspension at 298 K. The experimental data of viscosities is compared with the VFT (Vogel-Fulcher-Tammann) eq. A generalized multivariable correlation for the viscosity of diamond-THO nanofluid is presented as a function of temperature and nanoparticle loading.
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Experimental investigation of natural convection heat transfer characteristics in MWCNT-Thermal Oil nanofluid
Journal of Thermal Analysis and Calorimetry, 2018Co-Authors: Suhaib Umer Ilyas, Rajashekhar Pendyala, Marneni NarahariAbstract:The carbon nanotubes are considered as one of the highest Thermal conductive material which is having a variety of heat transfer applications. The suitability of carbon nanotubes in convective heat transfer is examined using multi-wall carbon nanotubes (MWCNT)-Thermal Oil-based nanofluids. Stable nanofluids are prepared in the concentration range of 0–1 mass% and Prandtl number range of 415 ≤ Pr ≤ 600 using ultrasonication. The natural convection heat transfer behavior is studied experimentally in a vertical rectangular enclosure with aspect ratio 4. The heat transfer experiments are conducted at varying heat flux in the range of 1594–3150 W m−2. The heat transfer coefficient, Nusselt number and Rayleigh number are estimated for MWCNT-Thermal Oil-based nanofluids and are compared with pure Thermal Oil. A significant deterioration in heat transfer coefficient is observed at higher concentrations of nanofluids. The study signifies the adverse impact on the cooling performance of MWCNT-Thermal Oil-based nanofluids in natural convection heat transfer, even though higher Thermal conductivities are observed in nanofluids. It is found that not only Thermal conductivity is essential property in heat transfer, but other thermophysical properties are also influential towards Thermal management.
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Investigation on the stability, Thermal characteristics and natural convection heat transfer in Oil-based nanofluids.
2018Co-Authors: Suhaib Umer IlyasAbstract:Thermal Oils are widely used as cooling media in heat transfer processes. However, their potential has not been utilised exquisitely due to low Thermal properties. The addition of nanoparticles in Thermal Oil can improve Thermal properties.
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An experimental study on the natural convection heat transfer in rectangular enclosure using functionalized alumina-Thermal Oil-based nanofluids
Applied Thermal Engineering, 2017Co-Authors: Suhaib Umer Ilyas, Rajashekhar Pendyala, Marneni NarahariAbstract:Abstract The nanofluids are considered as an effective medium for Thermal transport in various applications due to improved properties. Limited experimental studies are accomplished on the convective heat transfer of nanofluids. Natural convective heat transfer behavior in nanofluids is experimentally studied in a vertical rectangular enclosure (aspect ratio = 4) with one heating and one cooling wall. The fluid under investigation is a novel and highly stable functionalized alumina-Thermal Oil-based nanofluid. The investigations are carried out for different concentrations of nanofluids ranging from 0 to 3 wt%. The effectiveness of the natural convection heat transfer process is mainly dependent on the properties of cooling media. The measured thermophysical properties of nanofluids are used for the estimation of heat transfer characteristics with a Prandtl number range of 228–592. The heat transfer coefficient and Nusselt number are obtained at different nanoparticle concentrations. A heat flux is applied on the hot wall with a range of 1593.75–3150 W/m 2 . An improvement in the cooling performance of nanofluids is observed. The high nanoparticle concentrations of nanofluids exhibit higher heat transfer coefficient as compared to the pure Thermal Oil. A correlation is developed for the Nusselt number in terms of Rayleigh number (4.43 × 10 5 –2.59 × 10 6 ), nanoparticle concentration and effective thermophysical properties.
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Rheological behavior of mechanically stabilized and surfactant-free MWCNT-Thermal Oil-based nanofluids
International Communications in Heat and Mass Transfer, 2017Co-Authors: Suhaib Umer Ilyas, Rajashekhar Pendyala, Marneni NarahariAbstract:Abstract The viscosity of nanofluids is one of the important parameter for the design of heat transfer processes. The evolution of usage of nanofluids in heat transfer processes is gaining more industrial consideration due to excellent Thermal properties. However, limited attention is focused on the rheological behavior of nanofluids as of today. The multiwall carbon nanotubes (MWCNTs) are stabilized in Thermal Oil using ultrasonication and high stability is observed. The rheological behavior of Thermal-Oil based dispersant-free nanofluids are studied at varying high shear rates (100–2000 s − 1 ), temperatures (25–90 °C) and nanoparticle concentrations (0.1–1 wt%). The effect on the shear stress and viscosity by the addition of carbon nanotubes in Thermal Oil is discussed. The measured effective viscosity is compared with different theoretical conventional models. A significant increment in relative viscosity is observed at high concentrations of carbon nanotubes. A correlation is developed based on the temperature, nanomaterial concentration, and shear rate.
Evangelos Bellos - One of the best experts on this subject based on the ideXlab platform.
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Thermal performance comparison between Al2O3/Oil and SiO2/Oil nanofluids in cylindrical cavity receiver based on experimental study
Renewable Energy, 2018Co-Authors: Reyhaneh Loni, Alibakhsh Kasaeian, E. Askari Asli-ardeh, Barat Ghobadian, Evangelos BellosAbstract:Abstract In the current study, the Thermal performance of a solar dish concentrator using a cylindrical cavity receiver is experimentally investigated using different working fluids. The examined solar working fluids are two kinds of nanofluids (Al2O3/Thermal Oil and SiO2/Thermal Oil) and pure Thermal Oil. The investigated experimental setup includes the dish concentrator, the cylindrical cavity receiver, heat exchangers and a hydraulic circuit system. The Thermal performance of the solar system is compared by application of the examined nanofluids with the pure Thermal Oil. The results indicated that the average Thermal efficiency of the cylindrical cavity receiver using the Al2O3/Thermal Oil nanofluid has the highest value compared to application of the SiO2/Thermal Oil nanofluid and pure Thermal Oil operation in the steady-state period. Moreover, the Thermal loss coefficient ( U L ) of the cylindrical cavity receiver using the Al2O3/Thermal Oil nanofluid has a lower value than the application of the SiO2/Thermal Oil nanofluid and pure Thermal Oil. Thus, the application of the Al2O3/Thermal Oil nanofluid is recommended due to the higher Thermal efficiency compared to the other examined working fluids. Finally, three experimental models are suggested for the cylindrical cavity receiver using the Al2O3/Thermal Oil nanofluid, SiO2/Thermal Oil nanofluid, and pure Thermal Oil.
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optical and Thermal analysis of a linear fresnel reflector operating with Thermal Oil molten salt and liquid sodium
Applied Thermal Engineering, 2018Co-Authors: Evangelos Bellos, Christos Tzivanidis, Angelos PapadopoulosAbstract:Abstract Linear Fresnel collectors are promising technologies for the exploitation of solar irradiation in medium and high temperatures. In this study, a linear Fresnel collector with flat primary mirrors and a parabolic shape secondary reflector is investigated. The location of the secondary reflector is simply optimized and then the collector is investigated under different incident angles (transversal and longitudinal). The next step is the Thermal analysis of the collector with three different working fluids: Thermal Oil, molten salt and liquid sodium. The analysis is performed for temperatures up to 900 K with liquid sodium in order to examine the collector up to its stagnation temperature. Both the optical and Thermal analysis are conducted with SolidWorks Flow Simulation. According to the final results, the exergy performance of the collector is maximized at 700 K and it is 30.20% with liquid sodium and 30.05% with molten salt. Generally, liquid sodium was found to be the best candidate according to performance criteria, with molten salt and Thermal Oil to follow. The high heat transfer coefficient is the reason for the superior performance of the liquid sodium. Moreover, the pumping work is maximized for operation with molten salt.
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Thermal, hydraulic and exergetic evaluation of a parabolic trough collector operating with Thermal Oil and molten salt based nanofluids
Energy Conversion and Management, 2018Co-Authors: Evangelos Bellos, Christos Tzivanidis, Dimitrios TsimpoukisAbstract:Abstract The use of nanofluids in parabolic trough collectors is a promising technique for enhancing their performance. This study investigates the dispersion of CuO nanoparticles in Syltherm 800 (Thermal Oil) and in nitrate molten salt (60% NaNO 3 – 40% KNO 3 ). The objective of this work is to examine the Thermal efficiency enhancement margin of the utilization of nanofluids for two usual working fluids (Thermal Oil and molten salt) as base fluids. Moreover, this work includes hydraulic analysis about the pressure losses and exergetic analysis in order to evaluate the total performance of the collector. The module of LS-2 parabolic trough collector is examined with a computational fluid dynamics program developed in SolidWorks Flow Simulation. The model accuracy is checked with Thermal efficiency and flow criteria using literature results. The simulations are conducted for temperatures up to 650 K for Oil cases and up to 850 K for molten salt cases. According to the final results, the use of Oil-based nanofluids leads to Thermal efficiency enhancement up to 0.76%, while the use of molten salt-based nanofluid up to 0.26% Thermal efficiency enhancement. The Nusselt number enhancement is found up to 40% for Syltherm 800-CuO and up to 13% for molten salt-CuO.
