Therminol VP-1 Research Articles

Techno-economic analysis and optimization of 50 MWe linear fresnel reflector solar thermal power plant for different climatic conditions

The climate change crisis is primarily associated with carbon dioxide emissions from fossil fuel-based electricity generation, which significantly contribute to the greenhouse gas effect. The implementation of renewable energy technologies can mitigate environmental impacts and promote a sustainable future. This study aimed to conduct a techno-economic feasibility analysis and optimize performance parameters for a 50 MWe capacity Linear Fresnel Reflector (LFR) concentrated solar power plant for nine stations under various climatic conditions. The analysis was conducted based on Levelized Cost of Electricity (LCOE) and Capacity Factor (CF) to select a suitable Heat Transfer Fluid (HTF) for each station, by varying Solar Multiple (SM) from 1.0 to 6.0 and adjusting Thermal Energy Storage (TES) hours from four to sixteen. The HTFs selected for economically feasible projects at different stations were Hitec Solar Salt, Hitec, and Therminol VP-1. The combination of SM and TES hours was optimized for economic feasibility, targeting a minimum CF of 36 % and a maximum LCOE of 13.0 ¢/kWh. The optimum SM and TES hours were found to range from 2.0 to 5.8 and from six to thirteen, respectively. An LCOE of less than 7.5 ¢/kWh and a CF of more than 80 % was achieved for two stations with SM of 6.0 and TES of 16 h using Therminol VP-1. Stations with annual mean direct normal irradiance values higher than 1500 kWh/m2 and clearness index values over 0.58 are suitable for commercial power plants. This study contributes to achieving the United Nation's sustainable development goals by promoting the use of renewable energy technologies.

An exergoeconomic exploration of solar-geothermal integration

This study investigates the integration of a solar field using parabolic trough collectors into a binary geothermal plant with isopentane as the secondary fluid, employing the Engineering Equation Solver (EES) and System Advisor Model (SAM) for analysis. The investigation evaluates the performance of two Heat Transfer Fluids (HTFs)—Therminol VP-1 and molten salts—in hybrid configurations, emphasizing variations in solar field size and thermal storage capabilities. First, a direct correlation has been identified between second law efficiency and Levelized Cost of Energy (LCOE), demonstrating that increases in thermal storage from 0 to 12 h result in LCOE increments up to 33%. The study highlights that molten salts, achieving the lowest LCOE of 0.075 USD/kWh, enhance net energy output by up to 15.55% compared to Therminol VP-1, particularly under extended storage conditions. Additionally, the integration of larger solar fields and increased storage capacities significantly impacts the costs of high-pressure steam production, which rise from 33.02 to 50.55%. By expanding plant capacity factors up to 97% for Therminol and 93% for molten salts with optimal thermal storage and solar multiple configurations, the study demonstrates that molten salts enable greater annual power output despite lower capacity factors. This comprehensive analysis underscores the pivotal role of second law analysis in optimizing the economic and operational efficiencies of hybrid geothermal-solar power systems, offering significant insights for enhancing the design and economic viability of renewable energy integrations.

The effect of adding hybrid nanoparticles (Al2O3–TiO2) on the performance of parabolic trough solar collectors using different thermal oils and molten salts

Enhancing the operational efficiency of parabolic trough solar collector (PTSC) systems is key to the advancement of solar energy technologies that enhance power generation sustainability. In the quest for efficient, environmentally friendly energy sources, solar energy systems have been a major focus of both researchers and industry. Adding hybrid nanoparticles (Al2O3–TiO2) to different base fluids of thermal oil or molten salts and then simulating the PTSC's energetic and exergetic performance is pivotal to efficiency enhancement. The focus of this paper will be on three thermal oils Syltherm-800, Therminol VP-1, and Therminol 75 that are used as base fluids with the addition of hybrid nanoparticles. Molten salts such as Solar Salt, Hitec, and HitecXL, which are considered different base fluid types, are also simulated with the same hybrid nanoparticle combination. The inlet temperature is found to be a determining factor in the choice of the base fluid. Inlet temperatures in the range of 300–650 K for thermal oils with the addition of Al2O3–TiO2 have improved the thermal and exergy efficiency of the PTSC by approximately 0.99 % and 0.59 %, respectively. Therminol VP-1/Al2O3–TiO2 has the highest average thermal efficiency among other thermal oils, with an average percentage of 71.68 %, while Syltherm-800/Al2O3–TiO2 has recorded the highest exergy efficiency of 24.1 %. At higher inlet temperatures above 500 K mixing Al2O3–TiO2 with molten salts has increased both energetic and exergetic PTSC performance by approximately 0.60 %. Solar Salt/Al2O3–TiO2 has the highest average thermal and exergy efficiency of 61.8 % and 36.1 %, respectively.

Solar-assisted clean steam generator, a cleaner production approach for sustainable healthcare facilities

Healthcare sector buildings, particularly hospitals, significantly contribute to global energy consumption and greenhouse gas emissions. Hospitals require a substantial amount of steam, including the essential hygienic or “clean steam,” that is currently supplied mostly by heaters and fossil fuel-based boilers. This study proposes a solar-driven clean steam generator, employing LS-2 parabolic trough collectors with Therminol VP-1 as the working fluid, to supply clean steam in hospitals. The system was designed and techno-economically assessed for two case study hospitals in Denmark and Sweden using MATLAB. The proposed system's proficiency was compared against existing solutions, revealing that it can contribute up to 19% and 22% of the energy requirements for the Danish and Swedish hospitals, respectively, in certain months. While the design may not enhance energy and exergy efficiencies due to inherent losses, it significantly reduces environmental impact, preventing 67.8 tons and 75.5 tons of equivalent CO2 emissions per year for the Danish and Swedish hospitals, respectively. This innovation aims to contribute to the healthcare sector's sustainability.

Energy and exergy studies on the receiver models with materials and heat transfer fluids.

This work focuses on meeting the growing demand in solar energy conversion for small-scale applications. In this regard, experimental and CFD research has been done to examine the thermal performance (energy and exergy efficiencies) of a dish collector (reflector and receiver) system with different receiver models. In this work, receivers with uniform absorber cavity areas having cylindrical and hemispherical shapes were modeled for length-to-diameter ratios (L/D) of 1.5, 1, and 0.75. The modeled receivers having coil tube configurations concerning the geometrical shape of the models were tested with two different materials of aluminum and copper. The performance of the receiver models was compared by experimental and CFD methods for the average solar direct normal irradiations of 860 W/m2 by the dish reflector area of almost 12 m2. The supplied average heat flux by the dish reflector was 7kW/m2 at the absorbing area of the cavity receivers. The energy and exergy efficiencies from the experimental and CFD analyses on the models were determined based on the cavity surface temperature distribution of receiver walls, and heat gain for different mass flow rates by the heat transfer fluid water. The receiver with copper material and L/D ratio of 0.75 has been found as the optimized one among all other models with the maximum obtained energy and exergy efficiencies of 73.64 and 7.31% when water is used as the heat transfer fluid. The performance of the optimized receiver model was also validated with a few other heat transfer fluids such as SiC + water nanofluid and therminol VP1.

Investigation of the Thermophysical Properties of Nanofluids Based on Metal Oxides: Application in Concentrated Solar Power Plants

Solar energy is a renewable source of energy that does not emit greenhouse gases. The sun is free, inexhaustible and available all over the world. The sun's rays can be used to produce energy in two ways. The first technique converts the sun's rays into electricity using photovoltaic panels, while the second converts the sun's rays into heat using concentrated solar power plants (CSP). Several studies have been carried out with the aim of improving the performance of these solar power plants in order to achieve high efficiency, which is the case in our study. In this work a numerical study was carried out on the effect of nanoparticles on the thermophysical properties of nanofluids with the aim of determining the most optimal nanofluid for use as a heat transfer fluid in concentrated solar power plants. The nanoparticles examined were metal oxides (SIO2, MgO and Fe3O4), which were dispersed in Therminol VP-1 and Syltherm 800. The thermophysical properties examined were density, thermal conductivity and heat capacity. To carry out this study, we set the temperature from 200 to 400°C at the same operating temperature as the concentrating solar power plant.After evaluating the effect of nanoparticles on the thermophysical properties, we studied the behaviour of the CSP plant based on nanofluids using SAM (System Advisor Model) software. The results obtained are very encouraging and show that the addition of nanoparticles to a base fluid improves its thermophysical properties compared with the pure base fluid, and the rate of improvement in thermal conductivity exceeds 9%. We also found that the nanofluid (Fe3O4 /Therminol Vp1) is the best selected for use as a heat transfer fluid in concentrated solar power plants with an efficiency and thermal energy produced equal to 40.87% and 588164 MWht, respectively.

Investigation and optimization of the performance of a spectrum splitting photovoltaic/thermal system using multiple kinds of core-shell nanofluids

Core-shell nanofluids have better tunability than nanofluids containing nanoparticles made of a single material. Analysis and optimization of nanofluid parameters can help improve the performance of the nanofluid spectrum splitting photovoltaic/thermal system. This study develops and experimentally validates a numerical model of a double-pass nanofluid spectrum splitting photovoltaic/thermal system. The influences of core diameter, shell thickness, and concentration on the optical properties of 11 kinds of nanofluids are investigated, as well as the electrical and thermal performance of the system using the nanofluids as working fluids. Using the genetic algorithm, with electrical and thermal constraints, parameters are determined to achieve the best performance. Results indicate that, when using water as the base fluid, among these kinds of nanofluids, the optimized performance is very similar. The biggest difference in the outlet temperatures is 0.15 K with electrical constraint, while that in the electrical efficiencies is 0.18 % with thermal constraint. After changing constraint, the outlet temperatures in the optimization results decrease by about 1 K, while the electrical efficiencies increase by more than 1.5 %. Using Therminol VP-1 as the base fluid, the optimized performance is also similar. For the system studied, water is a more suitable base fluid than Therminol VP-1.

Performance analysis of a novel direct absorption parabolic trough solar collector with combined absorption using MCRT and FVM coupled method

Direct absorption parabolic trough solar collector (DAPTSC) using nanofluid absorber has been demonstrated as an efficient technology for exploiting solar energy at high temperature. However, most mono nanofluids are unable to achieve broadband absorption and hybrid nanofluids are unstable at high temperature. In this work, the mono nanofluid and optical glass combined absorption is proposed for the DAPTSC. In which the absorption glass (HB850) and an outer glass tubes form an annular space for indium-tin-oxide (ITO)/Therminol VP-1 nanofluid flowing. Monte Carlo Ray-Tracing and Finite Volume Method (MCRT-FVM) coupled model is developed and validated for system investigation. The results show that the novel collector with the combined absorber exhibits obvious enhancement in thermal performance compared to Therminol VP-1 or ITO/Therminol VP-1 nanofluid. The DAPTSC with concentric annular tube (CAT) has a significantly superior thermal performance to that of the single tube collector, with 45.91 % higher achievable temperature gain and 1.15 % more achievable exergy efficiency. Finally, an eccentric annular tube (EAT) is proposed for further improvement. To quantify the performance improvement of the DAPTSC with EAT, a comparison has been made to that of a DAPTSC with CAT. The results indicate that EAT configuration shows 1.96 % enhancement in the exergy efficiency.

Performance assessment of a solar aided dual-fuel supercritical steam power plant for power boosting under different operating loads

Fuel supply due to political conflict and decarbonization is the most challenging standup for the energy sector and electricity generation. Therefore, the present study introduces a thermodynamic analysis for a modeled supercritical solar aided power plant (SAPP) using two types of fuel at different operating loads, i.e., 50%, 75%, and 100%. The proposed SAPP is investigated in terms of energy, exergy, and steam flow rates to verify the advantages of using SAPP over conventional power plants. In the SAPP, the condensate water passes into the heat exchangers using a working fluid of Therminol VP-1. Additionally, the turbine extraction steam at 100% load is minimized, and it is eliminated at 50% and 75% loads. The results show that the recovered amount of feed water extraction increases the mechanical power for SAPP-based natural gas in comparison with the conventional supercritical steam power plant by 16, 21, and 9.7% at an operating load of 50%, 75%, and 100%, respectively. Consequently, SAPP-based natural gas maintains an increase in the overall energy efficiency compared with the CPP of 13.7, 17, and 1.9% at an operating load of 50%, 75%, and 100%, respectively. As well, the mechanical power of the SAPP-based oil fuel increases compared with CPP by 25.7, 27.6, and 17.4% at 50%, 75%, and 100% loads, respectively. Whereas, the overall energy efficiency enhances due to using the SAPP-based oil fuel compared with that of the CPP by 20.6, 21.9, and 7% at a load of 50%, 75%, and 100%, respectively.

Thermal performance analysis of the parabolic trough solar collector in the Sub-Saharan climate of the Central African Republic

This work proposes a mathematical model of the PTSC in one dimensional (1-D) simulated under the sub-Saharan climate conditions of the Central African Republic (CAR). An optical model of the PTSC system is proposed. Four thermal models of the support bracket were used resulting in four thermal models of the PTSC in addition to a thermal model without support bracket. The Gauss-Seidel method is used and simulated with Matlab software. The five developed mathematical models submitted to validation tests in comparison with the Sandia National Laboratory data show that model 3 is the best with an error of 5.47 %, followed by 5.54 % model 0, 5.69 % model 1 and 5.95 % model 2. The thermal effects of the support bracket on the absorber outlet temperature are quantified at 0.74 % for model 3, 2.61 % for model 1, 7.53 % for model 2 and 19.29 % for model 4 compared to the model without support bracket. The wind speed has significant impacts on the outlet temperatures. Three vegetable oils were used as heat transfer fluids (HTFs) in comparison with Therminol VP-1 showing a sensitivity to mass flow rate variations with high temperatures reached daily on average of about 200 °C for a flow rate of 0.04 kg/s.

A transient simulation for a novel solar-geothermal cogeneration system with a selection of heat transfer fluids using thermodynamics analysis and ANN intelligent (AI) modeling

Today, due to the reduction of fossil resources and on the other hand the high environmental pollution of these resources, it is necessary to pay attention to alternative resources, including clean and available renewable resources. In this study, solar and geothermal energy sources are combined, generating electricity, cooling, freshwater, and hydrogen, along with selecting a suitable heat transfer fluid for parabolic trough solar collectors. This system consists of parabolic trough solar collectors, a steam Rankine cycle, a steam Rankine cycle with an organic Rankine cycle, a proton exchange membrane electrolyzer, and a reverse osmosis desalination unit. To analyze the performance of solar collectors, Therminol 59, Marlotherm SH, Syltherm 800, and Therminol VP1 heat transfer fluids are selected. Solar radiation intensity, solar collector mass flow rate, turbine and pump efficiency, evaporator pinch-point temperature, and organic Rankine cycle turbine inlet temperature were investigated as design parameters affecting system performance. Maximizing energy efficiency and reducing cost rate were selected as two objective functions and determined using a multi-objective sorting genetic algorithm (NSGA-II). The results showed that Therminol 59 has the highest energy efficiency and net power output compared to other heat transfer fluids. Also, the proposed system produces 1140 kW of electricity in the optimal state, and in the best state, it has an energy efficiency of 32.39% and a cost of 36.32 $/GJ.

Numerical Investigation of the (Mono-Hybrid) Nanofluid Thermophysical Properties for Concentrated Solar Power Plant

Nanofluids became an essential solution for the improvement of efficient heat transfer fluids. Thus, it’s necessary to optimize their propreties. This paper investigates the effect of the temperature and the volume fraction on the thermo-physical properties of different nanofluids (Mono and hybrid) such as: Density, thermal conductivity, dynamic viscosity, kinematic viscosity, heat capacity and enthalpy in various nanoparticule concentrations and operating temperature. Two nanoparticles Al2O3, CuO were added to three different conventional base fluids namely: Therminol VP-1; Sylthrem 800; Dowtherm A, with several volume fractions, and various temperatures (200–400 °C). A numerical model was developed using MATLAB software, to evaluate the behavior of each thermo-physical property of the nanofluid that can be used as a working fluid in CSP applications and compared with their conventional fluids. The results show an improvement in thermo-physical properties compared to pure fluids for an optimal value of 4% for Al2O3. Also, the increase in temperature plays an important role in the decrease in viscosity, and their influence on other properties has also been noticed while the addition of nanoparticles to the pure fluid allow to increase the thermal conductivity by 13%. Finally, the (Al2O3 + CuO/Dowtherm A) hybrid nanofluid sems to be attractive to use in CSP applications.

Receiver parameter optimization for nanofluid-based parabolic trough concentrating plant: a case study

ABSTRACT The disadvantage of using nanofluids as a heat transfer fluid in the Parabolic Trough Concentrating solar power plant is increased pressure drops. Therefore, more attention should be paid to optimizing the receiver pipe diameter. The aim of this study was to optimize a new receiver to study the industrial process performance of nanofluid-based Parabolic Trough Concentrating plants in 4 different regions in southern Algeria (Hassi rmel, In salah, Tamnrasset, and Bechar). Nanoparticles (Al2O3, CuO) were added to both base liquids (Dowtherm A, Therminol VP-1). The methodology is based on a two-step approach: first, the effects of nanoparticles and temperature on the thermophysical properties of nanofluids, such as thermal conductivity, specific heat capacity, and density, are numerically investigated using the MATLAB program; second, nanofluids properties are integrated into SAM (System Advisor Model) software to perform a 50 MW parabolic trough solar power plant with 25% of a backup system and nanofluids in heat transfer system for the different representative locations of the climate of Algeria. The results of the first part show that the addition of nanoparticles increases the thermal conductivity and density of the nanofluid by 11% and 23%, respectively, and the specific heat capacity is proportional to temperature. The most favorable site is Insalah with an optimal SM egale to 3 and a capacity factor of 51%. Finally, the use of nanofluids as a heat transfer fluid in solar power plants plays a great role in improving its efficiency, the best choice for nanofluids under Algerian climates is CuO/Dowtherm A with an optimal tube diameter of 0.07 m.

Prioritization of heat transfer fluids in parabolic trough solar systems using CFD-assisted AHP-VIKOR approach

Parabolic trough solar collectors (PTSCs) are proven technologies and are used in various fields including concentrating solar power, integrated solar combined cycle, industrial process heat, air conditioning, and desalination. The selection of heat transfer fluid (HTF) is a part of the design consideration of concentrating solar technologies (CST) since its technical specifications have a significant effect on the system configuration, operating conditions, and levelized energy cost. Several HTFs including water, thermal oils, molten salts, and gases are already in use for PTSC systems, and others including liquid metals, ionic liquids, and nanofluids are still being tested. Each HTF has pros and cons; thermal and thermodynamic evaluations are practical to compare the performance of an HTF with that of its counterparts however they are insufficient to attribute a parabolic trough CST in terms of design concerns. This study has presented an integrated AHP-VIKOR (Analytical Hierarchy Process - VIekriterijumsko KOmpromisno Rangiranje) multi-criteria decision making (MCDM) approach assisted by computational fluid dynamics (CFD) to prioritize HTFs, particularly for CST and the results are compared to AHP-TOPSIS (Analytical Hierarchy Process - Technique for Order Preference by Similarity to Ideal Solution) for validation. While AHP is chosen to decide the criteria weights in the multi-criteria process, VIKOR is used as decision making to rank and prioritize alternatives. Water, Therminol VP-1, Solar salt, Hitec, Hitec XL, Liquid sodium, Lead-bismuth eutectic, Carbon dioxide, Air, and Helium are evaluated as the HTF inventory and a comprehensive CFD study is conducted to benchmark their thermal and thermodynamic properties in a high concentration PTSC in terms of solidification temperature, upper thermal stability, collector efficiency, pumping power consumption, receiver temperature gradient, and irreversibilities. In addition, other critical design considerations of HTFs including material cost, heat storage capability, material compatibility, operational safety aspects, operational maturity, and solar field control sophistication are taken into account in the MCDM process. Results show that the current parabolic trough CST should have priority for the HTFs of water and molten salt (Hitec) but molten metals and gaseous fluids would gain more insight in near future. This study presents an original perspective for deciding suitable HTFs in PTSC applications where thermal and thermodynamic analyses are limited.

Effectiveness of the use of nanofluids in concentrated solar power plants – Electrical and environmental assessment

Nanofluids are reported in the literature as advanced heat transfer fluids that improve significantly the thermo-physical properties of base fluids and, thus, enhance the performance of the solar systems. However, despite their great potential to improve the thermal and rheological properties when combined with a base fluid, it has been proven in this paper that they have a major limit that makes their integration in commercial scale CSP plants questionable. Indeed, based on various numerical simulations of three different nanofluids (MgO-VP1, Al2O3-VP1, Fe2O3-VP1), the results have revealed that when the base fluid (Therminol VP1) is doped with a certain volume fraction of nanoparticles, its circulation through the CSP’s canalization becomes more energy-intensive. Accordingly, the pumps’ electrical energy consumption increased proportionally with the nanoparticles’ concentration ratio. Consequently, when the nanofluids are used, the net energy production of the studied CSP plant (Noor I, Morocco) decreases compared to the reference case when the base fluid is used. From an environmental point of view, the use of nanofluids in CSP plants aggravates the negative environmental impact by increasing the GHG emissions related to the pumps’ operating process during the life cycle of the CSP plant. Thus, this article has a dual interest; on the one hand, it confirms the benefits of nanofluids on a thermo-physical level and, on the other hand, it highlights their major limitation from an energetic and environmental point of view, when used in CSP plants.

Performance study of a new parabolic trough design under optical concentrator effect

• A new hybrid parabolic trough concentrator is proposed. • A new algorithm for the hybrid trough concentrator is presented. • The influence of the optical concentrator on the hybrid system performance is studied. • Results showed a maximum thermal efficiency of 86 % corresponding to 318.9 Watts as additional electrical power while the heat losses are reduced from 2.76% to 1.9%. • The chemical interactions within Therminol VP1 stay stable and the hydrogen production rate remains at 2.90µmol/kg/h, reducing the possibility of cracking problems. The production of thermal and electrical energy by conventional and hybrid parabolic trough concentrators is widely considered most important in the field of renewable systems. In this work, two main problems of parabolic trough concentrators were studied with the aim of minimizing them as much as possible, namely, the cracking of Therminol VP1 and heat loss. The cracking problem of Therminol VP1 is one of the major troubles of parabolic trough systems at high temperatures (400°C) due to its dramatic consequences, which decrease significantly the thermal and electrical efficiency of parabolic trough concentrator. To address these issues, the temperature of Therminol VP1 was automatically controlled by a new parabolic trough concentrator integrated with two different types of tubular thermoelectric generators. A new mathematical model was offered for this hybrid system. In addition, a set of thirteen non-linear equations were discretized using the finite difference method. The discretized equations were coded in MATLAB (2015a) software based on the Gauss-Seidel technique with an accuracy of 0.001. To confirm the predicted results of the new numerical model, a literature paper was used for comparison. The comparison between the predicted and literature results was in good agreement. The effect of solar concentrator ratio on the thermal and electrical performance of the new system was analyzed and discussed. The major results show that the maximum thermal efficiency of the new system up to 86 % corresponding to 318.9 Watts of additional electrical power. Also, the maximum storage of hot water at 95 °C and Therminol VP1 at 400 °C up to 251.5 Liter/Day and 383.8 Liter/Day, respectively. Additionally, the cracking problem of Therminol VP1 was effectively controlled. More precisely, the hydrogen generation rate was automatically stabilized at a low and stable value of 2.90 µmol/kg/h. In addition, the heat losses rate was reduced from 2.97% to 1.07% with increasing solar concentration ratio. These results represent a useful reference for the selection of this new hybrid parabolic trough concentrator in view of its developed and intelligent performance.

Working fluid selection for the geothermal-solar hybrid cycle at Olkaria II power plant in Kenya

At Olkaria II power plant located in Kenya, the brine from the separator is re-injected back into the ground. This study analyzes a flash geothermal-solar hybrid cycle using the working fluids n-butane, n-pentane, cyclopentane, hexamethyldisiloxane and toluene in order to utilize the brine. The studied working fluids have no potential to deplete the ozone or cause global warming. The working fluids were analyzed in terms of net power output and pump power required. This was done by heating Therminol VP-1 fluid to a maximum temperature of 400 °C using the parabolic trough solar collector and varying the working fluids mass flow rate, Therminol VP-1 flow rate and pressure, and the brine pressure and flow rate. They were varied to investigate their effect on the power output of the Organic Rankine Cycle. The working fluid with higher net power output was selected as a suitable working fluid for the hybrid cycle. The selected working fluid was used to determine the average hourly power output in each month of the hybrid system using the irradiance of Olkaria II power station. N-butane showed the best results in net power output hence it was selected as a suitable working fluid as compared to the other working fluids. When the hybrid system was analyzed using n-butane to obtain the hourly average power output in each month, the results revealed that the month of February has the highest hourly average power output where the Steam Turbine has an average hourly power output of 10.48 MW and Binary Turbine net power output of 18.56 MW. The minimum average hourly power output was obtained in the month of June where the Steam Turbine has an average hourly power output of 9.08 MW and Binary Turbine net power output of 16.88 MW.

Mathematical modeling of a binary ORC operated with solar collectors. Case study—Ecuador

<abstract> <p>The present study is significant because it can contribute to developing sustainable energy strategies and expanding knowledge about renewable energies in Ecuador, specifically by modeling two modules: the thermal module (parabolic solar collectors and energy storage tank) and the Organic Rankine Cycle (ORC) module. The objective was to determine a region in Ecuador where the thermal module exhibits the highest efficiency for solar collectors. Subsequently, a detailed analysis of the ORC module was conducted, considering the working fluid, boiling temperature, condensation temperature, pinch point temperature, solar collector area, and the collector area-to-energy storage volume ratio (<italic>Ac/V</italic>). Finally, an economic analysis was performed based on the Net Present Value (NPV), Internal Rate of Return (IRR), and payback period of implementing this type of system. After conducting all the respective analyses in the thermal module, while considering the yearly average meteorological data of ten years (2012–2022), it was determined that due to its meteorological conditions, ambient temperature (14.7 ℃) and solar beam radiation (184.5 W/m<sup>2</sup>), the efficiency of the collectors in the Andean region of Ecuador is higher. This efficiency is further enhanced by using Therminol VP-1 as the thermal fluid, as it possesses better thermodynamic properties than the other fluids analyzed. Similarly, the ORC module analysis results determined that cyclohexane is the working fluid for the ORC, thereby leading to a higher ORC efficiency (25%) and overall system efficiency (20%). Finally, the system was optimized to maximize the IRR and minimize the <italic>A</italic>c/<italic>V</italic> of the collector for a nominal power of 92 kW. As a result, the optimal operating conditions of the system include a solar collector area of 1600 m<sup>2</sup>, an energy storage tank volume of 54 m<sup>3</sup>, an electricity production of 23757 MW/year, a total system efficiency of 22%, an IRR of 15.65% and a payback period of 9.81 years.</p> </abstract>

Thermodynamic Modeling and Analysis of a Solar and Geothermal-driven Multigeneration System Using TiO2 and SiO2 Nanoparticles

In this study, renewable energy sources including a high-temperature solar parabolic trough collector and geothermal water integrated with a modified Kalina cycle, a combined ORC-EJR cycle, an electrolyzer, an RO desalination unit, and a domestic water heater. SiO2 and TiO2 nanoparticles dissolved in Therminol VP1 are applied as the working fluid of the solar collector. A comparative analysis of introduced working fluids is performed from energy, exergy as well as cost analysis point of view to evaluate their efficiencies. Solar irradiation, ambient temperature, and collector inlet temperature were the parameters investigated to discover their effects on energy and exergy efficiency, solar collector outlet temperature, hydrogen production rate, and freshwater production rate. The highest generated outlet temperature of the solar collector outlet was 693.8 K obtained by Therminol VP1/SiO2 nanofluid. The maximum energy and exergy efficiencies of the proposed system were 36.69 % and 17.76 %, respectively. Moreover, it is found that by increasing the solar collector inlet temperature, the hydrogen production rate decreases while the water production rate increases.

A potential solution in reducing the parabolic trough based solar industrial process heat system cost by partially replacing absorbers coatings with non-selective ones in initial loop sections

An important step to achieve low-emission production is the integration of solar energy into industrial processes for decarbonizing the industrial sector. It is therefore necessary to attempt to minimize the cost of these solar industrial process heat systems. The article presents a strategy to reduce the investment costs and thus increase the popularity of parabolic trough collectors by partially replacing the expensive selective coating with a high absorptive, low-cost, non-selective coating in the initial sections of the solar loop where the heat transfer fluid temperature is lower. The analysis was performed for 4 case studies reflecting commercially available solutions with varying temperature ranges for different industrial applications. Calculations were performed using the two-dimensional developed mathematical model that validated with experimental data. The assumed heat transfer fluid is Therminol VP-1. The results have shown the potential of partial use of the Pyromark coating for low and medium-temperature industrial process heat systems with inlet–outlet temperature ranges of 60–120 °C and 100–200 °C. The analysis also showed that all the absorbers can be covered with a low-cost coating in the first scenario. Efficiency increases from 1.5 to 5.5 percentage points have been observed. For the second scenario, 15 of the 24 absorbers can be covered with a low-cost coating, when the installation works at a solar irradiance of 800 W/m2. Since the results are depended on the solar irradiance and the chosen regulation strategy of the flow, the final number of absorbers possible to cover with non-selective coating requires a long-term analysis for each case examined.