Thermal Oils Research Articles

Hybridization of CSP Plants: Characterization of a Molten Salt Heater for Binary and Ternary Nitrate Salt Mixtures Fueled with Gas/Biogas Heaters

Hybridization of CSP plants with alternative energy sources (fuels) represents a means to improve flexibility of operation, power dispatchability and utilization factor of the plant. New generation CSP plants make use of molten salts as Heat Transfer Fluid (HTF) besides Thermal Energy Storage (TES) medium. Therefore, proper interfaces should be developed to effectively transfer the heat from the back-up source to the molten salt. This paper presents the results obtained in the experimental validation of an innovative gas-fueled Molten Salt Heater (MSH) prototype. The objective of this research is to validate the MSH design, where the specific properties of molten salts (compared to other HTFs, e.g., thermal oils) have to be taken into account. The developed reduced-scale MSH (90 kW thermal) consists of a heat exchanger with the molten salt flowing inside finned tubes cross-flowed with the hot flue gas generated in an upstream combustion chamber. LPG or a biogas-like mixture has been used as gas fuel. Experimental results have been obtained with two different molten salt mixtures: the “solar salt” binary mixture (NaNO3/KNO3, 60/40%w) typically used in CSP applications (up to 565 °C) and the ternary mixture known as Hitec XL® containing sodium/potassium/calcium nitrates (NaNO3/KNO3/Ca(NO3)2, 15/43/42%w) characterized by lower freezing temperatures. Experimental tests have been carried out changing some operative parameters like the flow rate of the molten salt (0.45–0.94 kg/s), the inlet temperatures of the molten salt (303–445 °C) and of the hot gas (596–632 °C). For both molten salt mixtures, it was demonstrated that heat transfer correlations based on the Dittus-Boelter equation allow to predict experimental results with <10% deviation between experimental and theoretical values of the heat transfer coefficient.

Assessment and Perspectives of Heat Transfer Fluids for CSP Applications

Different fluid compositions have been considered as heat transfer fluids (HTF) for concentrating solar power (CSP) applications. In linear focusing CSP systems synthetic oils are prevalently employed; more recently, the use of molten salt mixtures in linear focusing CSP systems has been proposed too. This paper presents a comparative assessment of thermal oils and five four nitrate/nitrite mixtures, among the ones mostly employed or proposed so far for CSP applications. The typical medium-size CSP plant (50 MWe) operating with synthetic oil as HTF and the “solar salt” as TES was considered as a benchmark. In the first part of the paper, physical properties and operation ranges of different HTFs are reviewed; corrosion and environmental issues are highlighted too. Besides an extensive review of HTFs based on data available from the open literature, the authors report their own obtained experimental data needed to thoroughly compare different solutions. In the second part of the paper, the impact of the different HTF options on the design and operation of CSP plants are analyzed from techno-economic perspectives.

Kinematics of steam film wetting while quenching cylindrical samples in thermal oils

The paper presents the determination of the velocity of the vapor front along the outer wall of a cylindrical specimen in the process of two-dimensional axisymmetric quenching of the samples in thermal oils. One thermal oil is Isorapid 277 HM heated to 40°C and the other thermal oil is Marquench 722 heated to 90°C. The experimental setup of the work consists of heating to a temperature of 850°C, then quenching three dimensionally different cylindrical probes. The dimensions of the probe were: ϕ25x100 ϕ50x150 and ϕ75x225 mm. All quenchings were done in strictly controlled conditions of the flow rate of the quenchant around the cylinder as well as maintaining the temperature of the quenchant within the maximum 40±2.5°C or 90d3°C, during the quenching of the samples. The velocity of movement of the steam front on the outer surface of the cylinder was determined from the time-measured values of temperatures at the marked points of each sample. The analysis of the steam front movement velocity along the cylinder wall starts from the moment the lower base of the probe touches the quenchant. During the process of immersing the test probe in the quenchant, in addition to measuring the temperatures in time, the time of lowering the probe to contact with the quenchant sample was also measured. The approximate average velocity of the vapor front was determined based on the indications of the lower and middle thermocouples located 1.5 mm below the outer surface of the cylinder wall. Based on the distance of one half the height of each probe and time, the velocity of the steam film movement or the kinematics of the steam film wetting was obtained. The obtained results were compared with the results of quenching in water and aqueous solutions of the same probes under the same strictly controlled conditions.

Crumpled particles of ethanol-wetted graphene oxide for medium-temperature nanofluidic solar-thermal energy harvesting

Direct absorption of sunlight with carbon nanofluids is a facile way to efficiently harvest solar-thermal energy, but poor dispersion stability of nanofluids under elevated temperatures severely limits their applications. Herein, we report a general strategy to prepare stably-dispersed medium-temperature solar-thermal nanofluids by employing crumpled particles of ethanol-wetted graphene oxide sheets as the self-dispersible photothermal converters. The crumpled particles simultaneously possess intensively-deformed surface structure, a low density and a small particle size. Such features weaken the inter-particle van der Waals attraction and gravitational sedimentation of the crumpled particles, thereby enabling their long-term stable dispersion within commercial thermal storage oils. Uniform dispersion of nanofluids was maintained after continuous heating for 2 weeks under a heating temperature up to 200 °C. The homogenously dispersed nanofluids also achieved high solar absorptance with low particle loadings, and retained the large heat capacity and suitable viscosity. These combined advantageous thermophysical properties enabled consistent high-performance medium-temperature direct absorption-based nanofluidic solar-thermal energy harvesting under large-flux solar illumination.

High temperature stability of a commercial terphenyl-based thermal oil

Thermal oils are nowadays largely employed as heat transfer fluids or cooling media in industrial and energy production plants. However, despite their widespread use, very few data are currently available about their chemical stability and possible composition changes in function of the operating temperatures, which are of crucial importance to evaluate the lifetime of these materials in real conditions.In the present work, a commercial terphenyl-based oil was investigated with respect to its thermal stability, performing ageing tests followed by a complete post-characterization analysis.To this purpose, a dedicated experimental set-up was designed and constructed to study the degradation processes, with a qualitatively and quantitatively analysis of the released gases and condensable products, together with a post-ageing characterization of the oil thermo-physical properties.The results show that the main decomposition mechanism involves the loss of hydrogen atoms, followed by partial polymerization processes, which explain the increase in dynamic viscosity and the decrease in volatility observed for the thermally stressed materials. Finally, the decomposition kinetic constants were estimated, obtaining a value of about 100 kJ/mol for the activation energy, which is in good agreement with the data available in the scientific literature.

Dynamic analysis of a novel standalone liquid air energy storage system for industrial applications

Liquid air energy storage (LAES) is increasingly popular for peak-load shifting of power grids, which includes air liquefaction at off-peak hours and power generation at peak hours. The standalone LAES system does not rely on external cold and heat sources, and hence is more favorable for applications. In the standalone LAES system, heat storage in the air liquefaction process and cold storage in the power generation process play a key role on the system performance. The previous studies often chose propane/methanol as cold storage materials, and thermal oils as heat storage materials, which show a relatively higher system performance. However, propane, methanol and thermal oils are flammable, have a high capital cost and require strict safety measures, which are unfavorable for some industrial applications. To address this issue, we propose a novel standalone LAES system with pebbles/rocks as both cold and heat storage materials in packed beds. Such stores have a low capital cost and a high chemical stability and have not been studied in detail before. The dynamic effect of packed beds on the proposed LAES system is investigated from start-up to stable operation for the first time. Our simulation results show that it takes ~10 days for the system to reach a stable operation from start-up mainly due to the cold accumulation in the packed bed, and the average liquid air yield increases from 0.23 at the start-up to 0.56 in the stable operation. Besides, the proposed LAES system gives a round trip efficiency of ~42.8% and a combined heat and power efficiency of ~82.1%. These findings provide valuable information for industrial applications of the LAES technology.

CONVERSION OF CHARACTERISTICS OF CENTRIFUGAL PUMPS TO VISCOUS LIQUIDS

The urgency of the work is due to the large use of modern industry centrifugal pumps for pumping viscous liquids. In the energy sector, this is the use of fuel oil and thermal power plants, mineral oils and oil and gas-based lubricants as reserve fuel, and so on.The use of the characteristics of centrifugal pumps for viscous substances requires their recalculation. These data show the relevance of the problem of recalculating the characteristics of centrifugal pumps for viscous substances.In the oil industry, thousands of centrifugal pumps operate at oil pumping stations and in oil refining processes.The conducted researches and the analysis of their results give the chance to control giving of the centrifugal pump in technological process of cracking of oil products on an example of application of ACS.Analytical researches of a technique of recalculations are given.The characteristic of centrifugal pumps by calculations of approximation coefficients by the method of least squares is given.The performed studies confirmed the theoretical data on the influence of liquid viscosity on the appearance of the characteristics of centrifugal pumps.Studies also show that a sufficiently high accuracy of calculations of characteristics from water to liquid is provided for high-speed pumps which are in the range n = 50–130, that is for low-speed and normal wheels of centrifugal pumps.With the improvement of fluid quality, the rotation of the wheel shaft deteriorates. Therefore, there is a need to have the characteristics of such pumps at different speeds. The construction of such characteristics is based on the theory of similarity of centrifugal pumps, from which the so-called proportionality formulas are obtained, which allow to list (Q–H) the characteristics of the pump when the speed changes.Bringing characteristics to the analytical form allows you to use the Ace feed control. The means of regulation by changing the speed provides a significant reduction in electricity consumption.These data show the relevance of the problem of recalculating the characteristics of centrifugal pumps for viscous substances.

Thermal Property Investigation in Nanolubricants via Nano- Scaled Particle Addition

In nanolubricants, the increase in scholarly attention has been attributed to the affirmation that they exhibit enhanced thermo-physical features and that they can also be used in various thermal applications. Some of these applications where they could be incorporated include solar energy harvesting, industrial applications, and heat exchanger effectiveness enhancement. Recently, various approaches have been employed to enhance the coefficient of heat transfer, especially between the fluid contact surfaces and the working fluids. When it comes to conventional fluids of heat transfer, examples being ethylene glycol/water, thermal oils, and water, some studies document that they exhibit limitations. For instance, these fluids exhibit low thermal properties when compared to the solids with which they interact. To respond to this dilemma, there have been efforts in this study to have the fluids’ thermal properties improved via nano-scaled particle addition, causing marked evolutions in the evaluations of the behavior of fluids of heat transfer. Indeed, findings suggest that in base fluids, when the solid particles are suspended, there tends to be an enhancement in the fluid’s energy transmission; hence, notable improvements in material thermal conductivity properties, besides the betterment of material heat transfer characteristics.

On the Thermal Conductivity Assessment of Oil-Based Hybrid Nanofluids using Extended Kalman Filter integrated with feed-forward neural network

Regarding their ability to enhance conventional thermal oils' thermophysical properties, oil-based hybrid nanofluids have recently been widely investigated by researchers, especially on lubrication and cooling application in the automotive industry. Thermal conductivity is one of the most crucial thermophysical properties of oil-based hybrid nanofluids, which has been studied in a minimal case of studies on the specific types of them. In this research, for the first time, a comprehensive data-intelligence analysis performed on 400 gathered data points of various types of oil-based hybrid nanofluids using a novel hybrid machine learning approach; the Extended Kalman Filter-Neural network (EKF-ANN). The genetic programming (GP) and response surface methodology (RSM) approaches were examined to appraise the main paradigm. In this research, the best subset regression analysis, as a novel feature selection scheme, was provided for finding the best input parameter among all existing predictive variables (the volume fraction, temperature, thermal conductivity of the base fluid, mean diameter, and bulk density of nanoparticles). The provided models were examined using several statistical metrics, graphical tools and trends, and sensitivity analysis. The results assessment indicated that the EKF-ANN in terms of (R = 0.9738, RMSE = 0.0071 W/m.K, and KGE = 0.9630) validation phase outperformed the RSM (R = 0.9671, RMSE = 0.0079 W/m.K, and KGE = 0.9593) and GP (R = 0.9465, RMSE = 0.010 W/m.K, and KGE = 0.9273), for accurate estimation of the thermal conductivity of oil-based hybrid nanofluids.

Single-Phase Natural Circulation Loop Using Oils and Ternary Hybrid Nanofluids: Steady-State and Transient Thermo-Hydraulics

Abstract Steady-state and transient behaviors of single-phase natural circulation loop (SPNCL) are investigated using four thermal oils (Therminol VP1, Paratherm CR, Dowtherm A, and Dowtherm Q) and water-based ternary hybrid (various combinations of different nature and shaped nanoparticles: Al2O3, Cu, carbon nanotube (CNT) and graphene) nanofluids as loop fluid. The influences of nanoparticle volume concentration and loop height-to-width ratio on the mass flow rate and total entropy generation rate of SPNCL are investigated. Results disclose that ternary hybrid nanofluids enhance flow initiation, reduce fluctuation and are expected to attain a steady-state faster than water. Steady-state mass flow rate increases/decreases for ternary hybrid nanofluid depending on the shape of the nanoparticle, and the total entropy generation rate decreases as compared to water. Thermal oil shows a higher mass flow rate and total entropy generation rate as compared to water. Al2O3–Cu–CNT–water and Paratherm CR show the best result among all ternary hybrid nanofluids and thermal oils, respectively. The nanoparticle shape decides the optimum nanoparticle volume fraction. Increasing the height-to-width ratio decreases the total entropy generation and upsurges the mass flow rate at specified input power. The optimum height-to-width ratio depends on the loop fluid.

Comparing single-phase thermal hydraulic performance of a right and left turn twisted tape insert in a tube

Single-phase heat transfer and pressure drop tests were conducted in a tube with two types of twisted tapes. Each tape had exactly similar physical parameters and were made of the same material except that each had an opposite twist that resulted in a clockwise and anticlockwise flow swirl, i.e., left turn and right turn, respectively. Each type had twist ratio of 4 and 5.5 on a 180° twist. The tapes were tested in a tube-in-tube heat exchanger having 2 m length. The internal tube of the heat exchanger had 19.05 mm outer diameter and 1.65 mm wall thickness. Fresh water and 30% water/glycol solution were used as cold and hot fluids. Experiments were performed with Reynolds number varying between 2500 and 11,500 at Prandtl numbers of 9 and 14. Heat transfer and pressure drop enhancement was observed compared to plain tube at all operating conditions with 6–7% higher thermal performance with tighter twist tape. The Left Turn tape with a twist ratio of 5.5 showed slightly better thermal performance beyond Re > 8000 and with a twist ratio of 4 beyond Re > 4000. Similar trends were observed for the pressure drop. This is the first time a study on the subject was initiated assuming that the earth’s rotational effect “could” play a role in the flow swirl pattern inside a conduit. It is recommended to carry out intensive work on the subject with different tape twist ratios, fluids and more importantly larger conduits. The information generated could be of interest to the Concentrated Solar Power industry that uses high-temperature thermal oils. Any improvement in performance could result in lowering the operational cost, and therefore suitable type of twisted tapes could be used for upper and lower hemispheres.

Technico-economic comparison of heat transfer fluids or thermal energy storage materials: A case study using Jatropha curcas oil

Thermal oils are omnipresent in processes using heat at high temperature as heat transfer fluids (HTFs) as well as thermal storage materials (TESMs), particularly in concentrating solar plants. In this study, a methodology for technico-economic comparison of HTF and TESM is proposed. Jatropha curcas crude oil (JaCCO), a non-edible vegetable oil, which has recently been proposed as an alternative to well-established heat transfer fluids (HTFs), is compared to some of these HTFs from an economic point of view. Two case studies were considered for the assessment, using the features of a pilot μ-CSP plant: (i) the oils are used only as a HTF or (ii) they are used as a HTF and a TESM. The degradation rate of the oils was considered as a parameter. The results show that from a technical point of view, the oils exhibit similar performance. The economic analysis was mainly impacted by the cost of oil per kWh of stored energy. For the plant using the oils as HTFs only, JaCCO would always be economically more attractive than the other oils if its replacement frequency is less than 8–25 times that of the other oils in the economic conditions assumed in this study.

Battery thermal management: An optimization study of parallelized conjugate numerical analysis using Cuckoo search and Artificial bee colony algorithm

Thermal management of heat-generating battery packs involve many operating parameters affecting its performance, efficiency, and maintenance. Heat generation (Qgen), conductivity ratio (Cr), Reynolds number (Re), spacing between the packs (Ws), and coolant Prandtl number (Pr) are the parameters selected as working parameters for conjugate thermal analysis and optimization. The thermal analysis of battery packs is carried out numerically using the finite volume method. Single and multi-objective optimization of thermal management characteristics, namely maximum temperature (Tb, max), average Nusselt number (Nuavg), and coefficient of friction (Fcavg) using Cuckoo search (CS) and artificial bee colony (ABC) algorithm is attempted. For faster numerical analysis, the developed code is parallelized using OpenMP paradigm. 25 coolants having Pr in the range 0.02 to 511.5 belonging to five categories i.e. gases, oils, thermal oils, nanofluids, and liquid metals, are adopted for optimization. Nuavg and Fcavg are not affected by Cr and Qgen, while Tb, max changes significantly. Ws, Pr, and Re impact these characters differently, demanding the need for optimization. Nanofluids and thermal oils have emerged as the best coolants for optimized thermal characteristics at higher heat generations. CS algorithm provided high fitness of objective functions in single-objective optimization, whereas the ABC algorithm converged with high fitness during multi-objective optimization.

Nusselt number analysis from a battery pack cooled by different fluids and multiple back-propagation modelling using feed-forward networks

In this article, analysis of average Nusselt number (Nuavg), which indicates the heat removal from the battery pack cooled by flowing fluid is carried out considering coupled heat transfer condition at the pack and coolant interface. Five categories of coolant, mainly gases, common oils, thermal oils, nanofluids, and liquid metals, are selected. In each coolant category, five fluids (having different Prandtl number Pr) are selected and passed over the Li-ion battery pack. The analysis is made for different conductivity ratio (Cr), heat generation term (Qgen), Reynolds number (Re), and Pr. Pr varying in the range 0.0208–511.5 (25 coolants) and Cr for each category of coolant having its own upper and lower limit are used to analyze the heat removed from the battery pack. Using single feed-forward network and integrating two feed-forward networks having multi-layers with back-propagation is employed for artificial neural network (ANN) modelling. In this modelling, the concept of the main network and space network is devised for multiple back propagation (MBP). The numerical analysis revealed that the temperature distribution in battery and fluid is greatly affected by increasing Cr. The maximum temperature located close to the upper edge of battery is found to get reduced significantly with the increase of Cr, but upto a certain limit above which reduction is marginal. The analysis carried out reveals that Cr and Qgen have no role in improving Nuavg while Pr and Re vary it significantly in each step. Moreover, Nuavg is found to increase with Re continuously irrespective of any Cr and Qgen. While, for oils with an increase in Pr and Re, Nuavg was found to reduce significantly. Nanofluids are found to be more effective in improving heat transfer from the battery pack when cooled by flowing nano-coolants over it. The MBP networks proposed are successfully trained, and hence they can be used for prediction of Nuavg.

Optimization and analysis of maximum temperature in a battery pack affected by low to high Prandtl number coolants using response surface methodology and particle swarm optimization algorithm

Thermal analysis of heat-generating battery pack cooled by several coolants is analyzed numerically. The coolant used are gases, oils, thermal oils, nanofluids, and liquid metals to find the best coolant for temperature distribution. The conductivity ratio between the battery and coolant, flow Reynolds number, and heat generation inside the pack is varied for each coolant. The axial temperature variation, which provides the location and magnitude of maximum temperature, is studied. The maximum temperature of the battery pack is analyzed using response surface methodology, optimization of maximum temperature is performed using particle swarm optimization algorithm, and regression analysis is carried out at the end of this work. The thermal analysis carried out reveals that the gas coolants are inefficient in providing lower temperatures while nanofluids are most suitable. The response surface reveals that the maximum temperature behavior is different for each category of coolant.

Maximum temperature analysis in a Li-ion battery pack cooled by different fluids

The use of Li-ion battery in electric vehicles is becoming extensive in the modern-day world owing to their high energy density and longer life. But there is a concern of proper thermal management to have consistent performance. Therefore, proper cooling mechanism to have a good life and reliability on the battery system is necessary. The main objective of this analysis is to assess the maximum temperature that causes thermal runaway when the battery pack is cooled by several fluids. Five categories of coolants are passed over the heat-generating battery pack to extract the heat and keep the temperature in the limit. Different kinds of gases, conventional oils, thermal oils, nanofluids, and liquid metals are adopted as coolants in each category. This analysis is a novel study which considers different categories of coolant and conjugate heat transfer condition at the battery pack and coolant interface. In each group of coolant, five types of fluids are selected and analyzed to obtain the least maximum temperature of battery. The flow Reynolds number (Re), heat generation (Qgen), and conductivity ratio (Cr) are other parameters considered for the analysis. The Nusselt number for air and water as coolant with increase in Re is studied separately at the end. The maximum temperature is found to increase with Qgen and decrease for Re and Cr. Thermal oils, nanofluids, and liquid metals are found to provide maximum temperature in the same range of 0.62 to 0.54. At the same time, gases have nearly the same effect at different values of Re and Cr.

Pressure drops, heat transfer coefficient, costs and power block design for direct storage parabolic trough power plants running molten salts

Direct circulation of molten salts in the solar field of parabolic trough solar power plants may be a possible breakthrough to decrease their levelized cost of electricity. While prototypes are being erected around the world, this study addresses the main concerns and changes that are related to the replacement of thermal oils by molten salts, i.e. pressure drops, heat transfer coefficient, anti-freezing solutions, cost and power block design. It combines: 1) an analytical comparison of both technologies with respect to pressure drops and heat transfers; 2) simulations of a 50 MWe/7.5 h-of-storage power plant, using NREL’s SAM software, providing details on the dynamics of the outputs and parasitics. It has been observed the following: 1) pressure drops in the solar field are smaller running molten salts instead of thermal oil, thanks to higher operating temperature ranges; 2) HitecXL molten salt leads to lower electricity consumption than Therminol VP-1 oil and Solar Salt (parasitics); 3) a 6.3% reduction of the levelized cost of electricity when running HitecXL, ∼14.80 c€/kWh, instead of Therminol VP-1, ∼15.80 c€/kWh; 4) simpler power block designs can be considered for the higher operating temperatures of molten salts, resulting in higher efficiencies and/or cheaper power blocks.

Comparative analysis of the linear Fresnel reflector assisted solar cycle on the basis of heat transfer fluids

The biggest challenges in recent scenario for conventional power plants are accessibility of fossil fuel and the emissions of harmful gases on its combustion. The integration with solar energy is the suitable solution to handle such issues. The concentrated solar power technology is one of the utmost promising concepts for the effective utilization of solar energy. Its performance significantly affected by the physical properties of heat transfer fluid. In the present work various heat transfer fluids such as water, thermal oils, and molten-salts are discussed. This work compares the effect of different parameters of heat transfer fluid. Further, it analyses the effect of use of these heat transfer fluids on the performance of solar cycle.

Experimental evaluation of thermophysical properties of oil‐based titania nanofluids for medium temperature solar collectors

AbstractThermal oils are widely used as working fluids in the medium temperature heat transfer applications including concentrating solar thermal collectors. However, the weak thermal characteristics of these oils are major drawbacks in their successful application in the medium‐high temperature solar collectors. Fortunately, the emergence of nanotechnology has provided the opportunity to alter thermo‐physical properties of base fluids by adding small amount of sub‐micron size solid particles possessing better properties. This paper presents an experimental investigation of thermophysical properties of an oil‐based nanofluid to be used in the medium temperature solar collector for enhanced thermal energy transport. The colloidal suspensions were prepared by dispersing different weight fractions (0.25 wt.%, 0.5 wt.%, 0.75 wt.% and 1.0 wt.%) of Titania nanoparticles in Therminol‐55 oil using two‐step method. Shear mixing and high energy ultrasonication was employed to achieve uniform mixing and de‐agglomeration of the nanoparticles in order to enhance the stability of the colloidal suspensions. Thermophysical properties of the nanofluids were determined as a function of nanoparticles concentrations in the temperature range of 25 °C–130 °C. The experimental results demonstrated substantial improvement in thermal conductivity of the nano‐oils with an increase in nanoparticles loading which further enhanced at higher temperatures. Dynamic viscosity and effective density displayed a decreasing trend against rising temperature which indicate the effectiveness of these nanofluids for medium temperature heat supply. Nano‐oils with superior thermal properties can improve the performance of medium temperature solar thermal collectors.

Technical and economic analysis of a CSP plant presenting a low freezing ternary mixture as storage and transfer fluid

The selection of a proper heat transfer (HTF) and storage (HSM) material is a key parameter in the design of a CSP system, especially in the employment of parabolic trough concentrating solar power plants (CSP). The use of nitrates as HTF, alternatively to thermal oils, can increase the CSP efficiency and several mixtures have been proposed at this aim. The most employed molten nitrate salt is the so called “solar salt” that presents several advantages but also a relative high liquidus temperature point of 238 °C. The use, either as HTF or HSM, of a low melting mixtures is currently considered a promising alternative to decrease the investment cost and improve the manageability of CSP plants. In this work, a low melting fluid was selected, composed of calcium, sodium and potassium nitrate, and proposed to be used both as HTF and HSM in a direct and active storage system. The electric LCOEs was calculated for a medium size (50 MWe) plant located at the Priolo Gargallo site (Sicily-Italy). In order to evaluate the obtained outcome, the identical procedure was carried out considering the same size and location, and the “solar salt” and a thermal oil as heat transfer fluids, with the former as storage medium. The comparison between the results show that there is a clear, although limited, economic benefit in using the ternary mixture.