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Experimental Study Of Quaternary Nitrate Nitrite Molten Salt As Advanced Heat Transfer Fluid And Energy Storage Material In Concentrated Solar Power
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Book Synopsis Experimental Study of Quaternary Nitrate/nitrite Molten Salt as Advanced Heat Transfer Fluid and Energy Storage Material in Concentrated Solar Power by : Sumeet Changla
Download or read book Experimental Study of Quaternary Nitrate/nitrite Molten Salt as Advanced Heat Transfer Fluid and Energy Storage Material in Concentrated Solar Power written by Sumeet Changla and published by . This book was released on 2015 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar energy is used to produce electricity by two methods namely photovoltaic and concentrated solar power plant systems. Concentrated Solar power plants hold a distinct advantage over photovoltaic, which is that of energy storage. Energy can be stored in thermal energy storage system during day time and can be used to dispatch energy during peak demand and during raining or cloudy days to produce electricity. All concentrated solar power plants in operation use sensible heat storage method to store energy. Sensible heat storage system have been used in industry owing to ease of dispatch ability. Currently a binary mixture of NaNO3 and KNO3 (Solar Salt) is being used in industry owing to advantages such as, environmentally safe, low vapor pressure, relatively low cost and easy availability, low viscosity and compatibility with plant piping system. Heat is transferred to energy storage material through heat exchanger by high temperature fluid using forced convection. One of the disadvantages of this salt is low energy storage density, which in turn requires large storage tanks to store the material adding to the cost of the plant. Another drawback of using this mixture is its freezing point being too high. Temperature tends to drop at night and as a result salts tend to freeze. Along with freezing of the salt being an issue, other issue is the salt tends to expand on being heated to reuse again, which may lead to significant damage to Heat transfer fluid pipe system. Auxiliary equipment are required to keep the salt from freezing which increases the cost of the plant. To mitigate the thermodynamic losses because of the presence of the heat exchanger, it has been suggested to use HTF and TES as same substance, which would result in elimination of heat exchanger and reduce thermodynamic losses. From energy point of view, the efficiency of TES is considered high. A new Quaternary nitrate/nitrite mixture has been developed whose melting is 100°C. However, the major drawback of the salt to be used as TES/HTF is its poor thermos-physical properties such as lower specific heat capacity. Earlier there have been reports of substantial improvement in thermal properties of organic/inorganic salts on being doped with nanoparticles in minute concentration. Nanoparticle, on being doped in base salt tend to induce nanostructure, which due to its high surface area and high surface energy increase the heat transfer property. In this work, silica nanoparticle of various sizes are doped in the base eutectic salt to increase its specific heat capacity. After doping the base salt with silica nanoparticle it was observed, that there is anomalous enhancement in the specific heat capacity of the eutectic mixture.
Book Synopsis Utilization of Molten Nitrate Salt Nonomaterials for Heat Capacity Enhancement in Solar Power Applications by : Ramaprasath Devaradjane
Download or read book Utilization of Molten Nitrate Salt Nonomaterials for Heat Capacity Enhancement in Solar Power Applications written by Ramaprasath Devaradjane and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Concentrated solar power (CSP) system use general thermodynamic cycle to produce electricity and thus the system efficiency is mainly determined by the working temperature of heat transfer fluid (HTF). Organic-based HTFs (e.g., mineral oil, ethylene glycol, etc.) were firstly used for this application. However, this has limited the working temperature of CSP around 300 °C since these organic material starts to decompose below 400 °C. Typical liquid salts are thermally stable to high temperatures (500~600 °C). Using these salts as HTF can significantly increase the working temperature and as a result the system efficiency can also be highly enhanced. For example increasing working temperature from 300 °C to 500 °C can simply increase Carnot efficiency from 48 % to 61 %. Moreover, these salts are eco-friendly and using them as HTF can reduce the potential environmental cost caused by the conventional HTF. These salts also have very low vapor pressure that can reduce the potential mechanical stress on the pipe / storage system caused by using the conventional HTF. Recently a binary liquid salt (NaNO3-KNO3; also termed as "solar salt") has been introduced and adapted in the most recent CSP plants. This solar salt is also used as thermal energy storage (TES) medium. Extra thermal energy collected in the daytime is stored in solar salt and kept in a TES for later use. When electricity demand peaks (e.g., evening time) solar salt in TES provide thermal energy to continue electricity production. One of the major challenges to use solar salt as HTF / TES is its high freezing point at 220 [degree]C. This has the potential risk of crystallization in a pipe / storage system in a harsh condition (e.g., rainy season) and can result in high maintenance & operation costs for extra freezing protection system (e.g., insulation, auxiliary heater, etc.). Adding Ca(NO3)2 to solar salt can dramatically decrease the freezing point (down to 120 [degree]C). However, this ternary salt mixture has relatively low thermo-physical properties. Doping this material with oxidized nanoparticles can improve these properties. Nanofluids are liquids doped with nanoparticles. They have been proposed for large enhanced thermo-physical properties. In this report, the low thermo-physical properties were highly enhanced by doping with nanoparticles (19 % increase by 1 % nanoparticle concentration by weight). The result of this study will be useful to develop advance HTF / TES material for CSP plants. This will also applicable for other high temperature HTF applications such as geothermal energy, nuclear energy, and other energy generation technologies using thermodynamic cycle.
Book Synopsis An Investigation on the Thermophysical Properties of a Binary Molten Salt System Containing Both Aluminum Oxide and Titanium Oxide Nanoparticle Suspensions by : Kunal Giridhar
Download or read book An Investigation on the Thermophysical Properties of a Binary Molten Salt System Containing Both Aluminum Oxide and Titanium Oxide Nanoparticle Suspensions written by Kunal Giridhar and published by . This book was released on 2017 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molten salts are showing great potential to replace current heat transfer and thermal energy storage fluids in concentrated solar plants because of their capability to maximize thermal energy storage, greater stability, cost effectiveness and significant thermal properties. However one of the major drawbacks of using molten salt as heat transfer fluid is that they are in solid state at room temperature and they have a high freezing point. Hence, significant resources would be required to maintain it in liquid form. If molten salt freezes while in operation, it would eventually damage piping network due to its volume shrinkage along with rendering the entire plant inoperable. It is long known that addition of nanoparticle suspensions has led to significant changes in thermal properties of fluids. In this investigation, aluminum oxide and titanium oxide nanoparticles of varying concentrations are added to molten salt/solar salt system consisting of 60% sodium nitrate and 40% potassium nitrate. Using differential scanning calorimeter, an attempt will be made to investigate changes in heat capacity of system, depression in freezing point and changes in latent heat of fusion. Scanning electron microscope will be used to take images of samples to study changes in micro-structure of mixture, ensure uniform distribution of nanoparticle in system and verify authenticity of materials used for experimentation. Due to enormous magnitude of CSP plant, actual implementation of molten salt system is on a large scale. With this investigation, even microscopic enhancement in heat capacity and slight lowering of freezing point will lead to greater benefits in terms of efficiency and cost of operation of plant. These results will further the argument for viability of molten salt as a heat transfer fluid and thermal storage system in CSP. One of the objective of this experimentation is to also collect experimental data which can be used for establishing relation between concentration of nanoparticles and change in thermophysical properties of molten salt for various types of nanoparticles.
Book Synopsis Molten Nitrate Salt Technology Development Status Report by :
Download or read book Molten Nitrate Salt Technology Development Status Report written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recognizing thermal energy storage as potentially critical to the successful commercialization of solar thermal power systems, the Department of Energy (DOE) has established a comprehensive and aggressive thermal energy storage technology development program. Of the fluids proposed for heat transfer and energy storage molten nitrate salts offer significant economic advantages. The nitrate salt of most interest is a binary mixture of NaNO3 and KNO3. Although nitrate/nitrite mixtures have been used for decades as heat transfer and heat treatment fluids the use has been at temperatures of about 450°C and lower. In solar thermal power systems the salts will experience a temperature range of 350 to 600°C. Because central receiver applications place more rigorous demands and higher temperatures on nitrate salts a comprehensive experimental program has been developed to examine what effects, if any, the new demands and temperatures have on the salts. The experiments include corrosion testing, environmental cracking of containment materials, and determinations of physical properties and decomposition mechanisms. This report details the work done at Sandia National Laboratories in each area listed. In addition, summaries of the experimental programs at Oak Ridge National Laboratory, the University of New York, EIC Laboratories, Inc., and the Norwegian Institute of Technology on molten nitrate salts are given. Also discussed is how the experimental programs will influence the near-term central receiver programs such as utility repowering/industrial retrofit and cogeneration. The report is designed to provide easy access to the latest information and data on molten NaNO3/KNO3 for the designers and engineers of future central receiver projects.
Book Synopsis Investigation of Thermophysical Properties of Enhanced Molten Salt Nanofluids for Thermal Energy Storage (TES) in Concentrated Solar Power (CSP) Systems by : Joohyun Seo (Ph.D.)
Download or read book Investigation of Thermophysical Properties of Enhanced Molten Salt Nanofluids for Thermal Energy Storage (TES) in Concentrated Solar Power (CSP) Systems written by Joohyun Seo (Ph.D.) and published by . This book was released on 2020 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concentrated solar power (CSP) technologies have a great economical and technical potential for energy production in future. Its incorporation with thermal energy storage (TES) overcomes one of the biggest challenges in most renewable energy technologies, the intermittency of energy supply by natural resources. TES with 15-hour storage capacity is already commercialized to operate a CSP plant for 24 hours a day. When the sunlight is concentrated by mirrors into a small focal point, a heat transfer fluid (HTF) transfers the collected heat to a turbine or an engine to produce electricity and any surplus heat to a TES unit for later use. Typical CSP plants used two different materials for HTF and TES, and thus several heat exchangers were necessary between HTF and TES. These heat exchangers can cause a significant temperature drop and associated thermodynamic penalties. The potential capital cost increase is also not negligible. Using a binary nitrate salt (termed as "solar salt") as a single storage fluid for both HTF and TES can not only simplifies the heat transport/storage system but also minimize a potential energy loss. Its high-temperature stability (over 500 °C) can also increase the overall thermodynamic efficiency. However, solar salt has a relatively high melting point (220 °C), and it is likely to freeze under a harsh condition such as nighttime, rainy, or cloudy day. As a result, an auxiliary heater is required for a freeze protection and can significantly decrease the power output. Hence, it is necessary to investigate alternative storage fluid whose melting point is low enough to minimize the energy loss. A ternary nitrate salt mixture (LiNO3-NaNO3-KNO3) has a very low melting point (~100 °C). Using this mixture as a single storage fluid for both HTF and TES in a CSP can significantly reduce the energy loss by the freeze protection but also enhance CSP's energy conversion efficiency. However, the heat storage density of these molten salts is typically low. Literature study shows that dispersing appropriate nano particles can enhance salts' heat capacity. This can not only reduce the required HTF and TES amount, but also reduce the size of thermal transport and storage systems (e.g., pipes, heat exchanger, and storage tanks). In this study, several commercial SiO2 nanoparticles were first dispersed into a ternary nitrate salt to see if it can enhance its effective heat capacity. Several SiO2 nanoparticles at different sizes were tested to investigate the effect of nanoparticle size. Fresh nanoparticles, then, were in-situ synthesized in a binary and ternary nitrate salts. Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and Mg(NO3)2·6H2O (magnesium nitrate hexahydrate) were induced to decompose in a molten nitrate salt to produce Al2O3 and MgO nanoparticles. The new method (Liquid to Liquid) for the sample preparation was used to increase the enhancement of specific heat of a binary nitrate salt with SiO2 nanoparticle. A modulated differential scanning calorimeter (MDSC; Q20, TA Instrument Inc.) was used to measure the effective heat capacity. A discovery hybrid rheometer (HR2, TA Instruments Inc.) was employed to measure the mixture's viscosity. A customized apparatus was built to measure its effective thermal conductivity. A figure of merit analysis was performed to predict the performance of the mixture. A scanning electron microscope (SEM: Hitachi S-3000N and S-5000H) was used for material characterization. Moreover, molecular dynamics simulation was performed to investigate the effect of nanoparticles on the observed property measurements.
Book Synopsis Theoretical and Experimental Determination of Chemical and Physical Properties of Novel High Thermal Energy Density Molten Salt Systems for Concentrating Solar Power (CSP) Storage by : Tao Wang
Download or read book Theoretical and Experimental Determination of Chemical and Physical Properties of Novel High Thermal Energy Density Molten Salt Systems for Concentrating Solar Power (CSP) Storage written by Tao Wang and published by . This book was released on 2014 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: By using thermodynamic modeling, new eutectic multi-component salt systems have been developed. On the basis of the melting points, the novel systems were categorized into low melting point (LMP) systems and high melting point (HMP) systems. LMP can be used to serve as heat transfer fluid for solar parabolic trough system while the HMP can be used in solar tower or dish systems. Both LMP and HMP systems were synthesized and their melting points and heat capacities were determined using Differential Scanning Calorimetry (DSC). The experimentally determined melting points have excellent agreement with the predicted values. The densities for the selected systems were experimentally determined by using both standard densitometer method and Archimedes's principle method. In liquid state, the density values of both LMP and HMP systems decrease linearly as temperature increases. Thermal stabilities of novel systems were determined using TG-DTA. The upper limit temperatures of thermal stability were evaluated for LMP and most of values were found in the range between 673.15K and 723.15K. Compare to LMP systems, HMP salt mixtures show much higher upper limit temperatures, which enable them to be applied as heat transfer fluid for high temperature solar energy collection systems. Thermal conductivities in solid states of salt mixtures were also tested using simplified inverse method. For both LMP and HMP systems, the thermal conductivities decrease as function of temperature. Life cycle information such as the corrosion behaviors of various metallic samples in contact with molten salt systems was determined using both electrochemical method and isothermal dipping method. When dipped inside the LMP systems, protective and dense oxide scales formed on the sample surface prevent any further severe corrosion. For HMP systems, Ni-201 alloy has excellent resistance to high temperature corrosion and can be considered as the construction material for molten salt container. On the basis of density, heat capacity and the melting point, energy storage densities of novel systems were calculated and compared to the existing binary solar salt and HITEC salt. The larger thermal energy density values of current molten salts indicate the better energy storage capacity for solar power generation systems.
Book Synopsis Novel Molten Salts Thermal Energy Storage for Concentrating Solar Power Generation by :
Download or read book Novel Molten Salts Thermal Energy Storage for Concentrating Solar Power Generation written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The explicit UA program objective is to develop low melting point (LMP) molten salt thermal energy storage media with high thermal energy storage density for sensible heat storage systems. The novel Low Melting Point (LMP) molten salts are targeted to have the following characteristics: 1. Lower melting point (MP) compared to current salts (222ðC) 2. Higher energy density compared to current salts (300 MJ/m3) 3. Lower power generation cost compared to current salt In terms of lower power costs, the program target the DOE's Solar Energy Technologies Program year 2020 goal to create systems that have the potential to reduce the cost of Thermal Energy Storage (TES) to less than $15/kWh-th and achieve round trip efficiencies greater than 93%. The project has completed the experimental investigations to determine the thermo-physical, long term thermal stability properties of the LMP molten salts and also corrosion studies of stainless steel in the candidate LMP molten salts. Heat transfer and fluid dynamics modeling have been conducted to identify heat transfer geometry and relative costs for TES systems that would utilize the primary LMP molten salt candidates. The project also proposes heat transfer geometry with relevant modifications to suit the usage of our molten salts as thermal energy storage and heat transfer fluids. The essential properties of the down-selected novel LMP molten salts to be considered for thermal storage in solar energy applications were experimentally determined, including melting point, heat capacity, thermal stability, density, viscosity, thermal conductivity, vapor pressure, and corrosion resistance of SS 316. The thermodynamic modeling was conducted to determine potential high temperature stable molten salt mixtures that have thermal stability up to 1000 °C. The thermo-physical properties of select potential high temperature stable (HMP) molten salt mixtures were also experimentally determined. All the salt mixtures align with the go/no-go goals stipulated by the DOE for this project. Energy densities of all salt mixtures were higher than that of the current solar salt. The salt mixtures costs have been estimated and TES system costs for a 2 tank, direct approach have been estimated for each of these materials. All estimated costs are significantly below the baseline system that used solar salt. These lower melt point salts offer significantly higher energy density per volume than solar salt - and therefore attractively smaller inventory and equipment costs. Moreover, a new TES system geometry has been recommended A variety of approaches were evaluated to use the low melting point molten salt. Two novel changes are recommended that 1) use the salt as a HTF through the solar trough field, and 2) use the salt to not only create steam but also to preheat the condensed feedwater for Rankine cycle. The two changes enable the powerblock to operate at 500°C, rather than the current 400°C obtainable using oil as the HTF. Secondly, the use of salt to preheat the feedwater eliminates the need to extract steam from the low pressure turbine for that purpose. Together, these changes result in a dramatic 63% reduction required for 6 hour salt inventory, a 72% reduction in storage volume, and a 24% reduction in steam flow rate in the power block. Round trip efficiency for the Case 5 - 2 tank "direct" system is estimated at>97%, with only small losses from time under storage and heat exchange, and meeting RFP goals. This attractive efficiency is available because the major heat loss experienced in a 2 tank "indirect" system - losses by transferring the thermal energy from oil HTF to the salt storage material and back to oil to run the steam generator at night - is not present for the 2 tank direct system. The higher heat capacity values for both LMP and HMP systems enable larger storage capacities for concentrating solar power.
Book Synopsis Molten Salts Chemistry and Technology by : Marcelle Gaune-Escard
Download or read book Molten Salts Chemistry and Technology written by Marcelle Gaune-Escard and published by John Wiley & Sons. This book was released on 2014-05-12 with total page 902 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written to record and report on recent research progresses in the field of molten salts, Molten Salts Chemistry and Technology focuses on molten salts and ionic liquids for sustainable supply and application of materials. Including coverage of molten salt reactors, electrodeposition, aluminium electrolysis, electrochemistry, and electrowinning, the text provides researchers and postgraduate students with applications include energy conversion (solar cells and fuel cells), heat storage, green solvents, metallurgy, nuclear industry, pharmaceutics and biotechnology.
Book Synopsis Molten Salt Technology by : David G. Lovering
Download or read book Molten Salt Technology written by David G. Lovering and published by Springer. This book was released on 2014-11-14 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Effect of Titanium Dioxide Nanoparticles on the Phase Diagrams and Thermophysical Properties of Nitrate Molten Salts by : Vamshidhar Reddy Vedire
Download or read book The Effect of Titanium Dioxide Nanoparticles on the Phase Diagrams and Thermophysical Properties of Nitrate Molten Salts written by Vamshidhar Reddy Vedire and published by . This book was released on 2017 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to their desirable thermophysical properties, nitrate molten salts are the main reason for studying the high-temperature storage medium in concentrated solar power plants. Low freezing point temperatures allow for safe operation of the power plant and for thermal energy storage fluids to be in a liquid state over an extended temperature range. Using portions of the obtained thermal energy to maintain the molten salt in its liquid state reduces the overall thermal efficiency of the power plant. Previous studies reveal that the addition of nanoparticles to the 60% NaNO3-40% KNO3 composition of molten salt decreases its freezing point temperature. The main objective of this study is to see how the freezing point temperatures of varying compositions of nitrate molten salts (30% NaNO3-70% KNO3|40% NaNO3-60% KNO3| 50% NaNO3-50% KNO3| 60% NaNO3-40% KNO3|70% NaNO3-30% KNO3) are effected when titanium dioxide nanoparticles of anatase phase of different volume fractions are added to it. In this study, nitrate molten salts are prepared and then tested using the differential scanning calorimeter (DSC) and scanning electron microscopy (SEM). The DSC tests allow for obtaining the thermal properties such as freezing point temperatures, specific heat capacities, and latent heat of fusion. Observations using the SEM provide an opportunity to quantify the morphological properties like size, the microstructure, and the dispersion of the nanoparticles in the molten salt.
Book Synopsis Deep Eutectic Salt Formulations Suitable as Advanced Heat Transfer Fluids by :
Download or read book Deep Eutectic Salt Formulations Suitable as Advanced Heat Transfer Fluids written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Concentrating solar power (CSP) facilities are comprised of many miles of fluid-filled pipes arranged in large grids with reflective mirrors used to capture radiation from the sun. Solar radiation heats the fluid which is used to produce steam necessary to power large electricity generation turbines. Currently, organic, oil-based fluid in the pipes has a maximum temperature threshold of 400 °C, allowing for the production of electricity at approximately 15 cents per kilowatt hour. The DOE hopes to foster the development of an advanced heat transfer fluid that can operate within higher temperature ranges. The new heat transfer fluid, when used with other advanced technologies, could significantly decrease solar electricity cost. Lower costs would make solar thermal electricity competitive with gas and coal and would offer a clean, renewable source of energy. Molten salts exhibit many desirable heat transfer qualities within the range of the project objectives. Halotechnics developed advanced heat transfer fluids (HTFs) for application in solar thermal power generation. This project focused on complex mixtures of inorganic salts that exhibited a high thermal stability, a low melting point, and other favorable characteristics. A high-throughput combinatorial research and development program was conducted in order to achieve the project objective. Over 19,000 candidate formulations were screened. The workflow developed to screen various chemical systems to discover salt formulations led to mixtures suitable for use as HTFs in both parabolic trough and heliostat CSP plants. Furthermore, salt mixtures which will not interfere with fertilizer based nitrates were discovered. In addition for use in CSP, the discovered salt mixtures can be applied to electricity storage, heat treatment of alloys and other industrial processes.
Book Synopsis Gibbs Energy Modeling of Binary and Ternary Molten Nitrate Salt Systems by : Tucker R. Elliott
Download or read book Gibbs Energy Modeling of Binary and Ternary Molten Nitrate Salt Systems written by Tucker R. Elliott and published by . This book was released on 2012 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molten nitrate salts have the potential to become efficient heat transfer fluids in many applications, including concentrated solar power plants and in energy storage systems. Their low melting temperatures and high energy densities contribute to this. Thus, an understanding of the phase diagrams of these salts is important, specifically, knowledge of the melting and freezing temperatures of these mixtures at various concentrations. Many previous works have investigated modeling these phase diagrams, particularly binary mixtures of nitrate salts. Ternary simulations for molten salts exist but results have been limited. Using existing enthalpy of mixing data for binary mixtures, an accurate ternary phase diagram has been constructed. The binary systems NaNO3- KNO3, LiNO3- NaNO3, and LiNO3- KNO3 and the ternary system LiNO3-NaNO 3-KNO3 have been modeled using a Gibbs energy minimization method. The predictions from this present model agree well with the results of experiments by our group and the data collected by previous researchers. The ternary predictions constructed using only binary interactions, agree reasonably well with the experimental data collected by our group. It is determined that the ternary mixture has a eutectic temperature of 107° Celsius at a composition of 43-47-10 mole percent LiNO3-KNO3-NaNO 3 respectively, and will be a viable heat transfer fluid. The thermodynamic model used here can be applied to any ternary system as well as any higher-order component system.
Book Synopsis Optical and Chemical Properties of Molten Salt Mixtures for Use in High Temperature Power Systems by : Stefano Passerini
Download or read book Optical and Chemical Properties of Molten Salt Mixtures for Use in High Temperature Power Systems written by Stefano Passerini and published by . This book was released on 2010 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: A future, robust energy portfolio will include, together with fossil fuel technologies and nuclear systems, a mix of renewable energy systems. Within each type of system there will also be variants used to strengthen a nation's baseload and/or peak power requirements. Among renewable energies, solar thermal systems are particularly promising in terms of their capability of contributing to the base-load power generation by providing enough thermal storage for continuous operation. In particular, direct volumetric absorption of the solar heat into molten salts seems to be a promising technology, in terms of efficiency and greenhouse gases emission reduction, which combines the good properties of molten salts as heat storage media with high operating temperatures. Accordingly, the selection of molten salts for this application required knowledge of the salts chemical behavior as well as optical properties. The molten salt selection and characterization was the objective of this Thesis. The light attenuation coefficient of two reagent grade molten salt mixtures (KNO 3 - NaNO 3, 40- 60 wt% and NaCI-KCI, 50-50 wt%) was measured and characterized over the wavelength range 400nm- 800nm and for different operating temperature ranges: 250*C-5000C for the nitrate mixture and 700*C- 8000C for the chloride mixture. The measurements were performed using a unique custom built experimental apparatus based on the transmission technique which combines high accuracy and flexibility in terms of experimental conditions and temperatures with simple layout, use of common lab materials and low cost. The experimental apparatus was validated using published data for both a room temperature fluid (water) as well as a high temperature fluid (a nitrate/nitrate mixture presenting a well known absorption edge shifting with temperature). No previous experimental works characterized molten salts in terms of light attenuation coefficient as a function of temperature and wavelength and under this point of view the obtained results represent unique and direct optical measurement for such a class of fluids. Furthermore, the obtained results are coherent to general theory on molten salts, described as semi-transparent liquids in the visible range and characterized by absorption edges in the ultra-violet and far-infrared regions. About 90% of the solar light emitted in the wavelength range 400nm-800nm is attenuated by 2m of nitrate salt, while about 80% of the solar light emitted in the wavelength range 400nm-800nm is attenuated by 2m of chloride salt. In addition, the chemical stability and material compatibility of molten salt mixtures (including nitrate/nitrite, chloride and carbonate salt mixtures) with common materials of interests were assessed partially through dedicated material compatibility tests and more extensively using a thermodynamic chemistry software, able to predict the equilibrium composition of systems of specified composition at different temperatures. The preliminary melting and material compatibility tests resulted in some of the previously identified salt mixture candidates to be discarded because of undesirable reactions with structural materials or air that made them not suitable for the CSPonD design project.
Book Synopsis A Device for Measuring Thermal Conductivity of Molten Salt Nitrates at Elevated Temperatures for Use in Solar Thermal Power Applications by : Spencer J. Nelle
Download or read book A Device for Measuring Thermal Conductivity of Molten Salt Nitrates at Elevated Temperatures for Use in Solar Thermal Power Applications written by Spencer J. Nelle and published by . This book was released on 2012 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Binary and Ternary mixtures of Molten Salt Nitrates are ideal candidates for future concentrating solar power (CSP) plant heat transfer fluids (HTFs) because of their high operating temperature limits resulting in greater Rankine efficiency. The inclusion of these HTFs into CSP plants is expected to revolutionize the industry by allowing for energy and cost savings that are attractive to potential plant developers and investors. It is vital for plant designers to have access to fully characterized thermo-physical properties of the intended HTFs, with thermal conductivity, viscosity, and specific heat capacity being the most crucial. Existing literature has not fully elucidated the thermo-physical properties of binary and ternary molten salt nitrates through their operating temperature range. This work presents the viscosity of eutectic ternary and binary compositions of molten alkali salt nitrates (Li-NO3, K-NO3, and Na-NO3) up to 550°C. A device to measure the thermal conductivity of these salts with accuracy at elevated temperatures was designed and built as no commercial offerings are able to withstand the corrosive nature of molten salt at high temperatures. The device is shown to accurately measure the thermal conductivity of water at room temperature. The present work is a step towards fully characterizing the thermo-physical properties of the aforementioned molten salts.
Book Synopsis The Effect of Silicon Dioxide and Titanium Dioxide Nanoparticles on the Thermal Decomposition Characteristics of Molten Salts at Elevated Temperatures by : Shalini Pogula
Download or read book The Effect of Silicon Dioxide and Titanium Dioxide Nanoparticles on the Thermal Decomposition Characteristics of Molten Salts at Elevated Temperatures written by Shalini Pogula and published by . This book was released on 2017 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Now a day's there is a strong motivation to explore the possibility of harnessing solar thermal energy around the world to produce electricity. Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants as it allows the plants to have energy availability and dispatch ability using industrial technologies. Rankine cycle is used to determine the efficiency of the CSP plants, the efficiency of the cycle is increased by 40% when the present working fluid (Therminol VP-1 whose efficiency is between 10--25%) is replaced with molten salts (a combination of 60 wt% NaNO3 and 40 wt% KNO3). Molten salts are used in CSP plants as a TES material because of the following advantages: high specific heat capacity and high thermal stability. Their main drawbacks are their relative poor thermophysical properties and the instability of molten salts above 550℗ʻC. To study the effects of nanoparticles (particles between 1 and 100 nanometers in size) on the drawbacks of fluids, the fluids are doped with nanoparticles thus obtaining the salt-based nanofluids. The present study experimentally determines the effect of nanoparticles (silicon and titanium dioxide) on the decomposition temperature of molten salts at elevated temperatures. Specific heat capacity is measured by using a differential scanning calorimeter (Perkin Elmer DSC 7), the experiment work has been carried out at different temperature range (400℗ʻC to 575℗ʻC). The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM). Thermogravimetric analysis (TGA) was carried out to study the mass loss and activation energy of the molten salt at elevated temperatures with varying mass concentrations of nanoparticles (1%, 5% and 9%).
Book Synopsis Advances in Concentrating Solar Thermal Research and Technology by : Manuel Blanco
Download or read book Advances in Concentrating Solar Thermal Research and Technology written by Manuel Blanco and published by Woodhead Publishing. This book was released on 2016-11-10 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: After decades of research and development, concentrating solar thermal (CST) power plants (also known as concentrating solar power (CSP) and as Solar Thermal Electricity or STE systems) are now starting to be widely commercialized. Indeed, the IEA predicts that by 2050, with sufficient support over ten percent of global electricity could be produced by concentrating solar thermal power plants. However, CSP plants are just but one of the many possible applications of CST systems. Advances in Concentrating Solar Thermal Research and Technology provides detailed information on the latest advances in CST systems research and technology. It promotes a deep understanding of the challenges the different CST technologies are confronted with, of the research that is taking place worldwide to address those challenges, and of the impact that the innovation that this research is fostering could have on the emergence of new CST components and concepts. It is anticipated that these developments will substantially increase the cost-competiveness of commercial CST solutions and reshape the technological landscape of both CST technologies and the CST industry. After an introductory chapter, the next three parts of the book focus on key CST plant components, from mirrors and receivers to thermal storage. The final two parts of the book address operation and control and innovative CST system concepts. Contains authoritative reviews of CST research taking place around the world Discusses the impact this research is fostering on the emergence of new CST components and concepts that will substantially increase the cost-competitiveness of CST power Covers both major CST plant components and system-wide issues
Book Synopsis Molten Chloride Salts for Heat Transfer in Nuclear Systems by : James Wallace Ambrosek
Download or read book Molten Chloride Salts for Heat Transfer in Nuclear Systems written by James Wallace Ambrosek and published by . This book was released on 2011 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:
