| 1. |
- Butean, Alex, et al.
(författare)
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A digital twin concept for optimizing the use of high-temperature heat pumps to reduce waste in industrial renewable energy systems
- 2024
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Ingår i: International Conference on Industry Sciences and Computer Science Innovation, iSCSi 2023. - : Elsevier B.V.. ; , s. 123-128
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Konferensbidrag (refereegranskat)abstract
- In light of the global industrial sector's steadfast pursuit of sustainable solutions to mitigate carbon emissions and efficiently minimize energy inefficiencies, the significance of novel approaches to energy optimization becomes increasingly evident. This research presents a novel digital twin concept that is designed to enhance the efficiency and effectiveness of high-temperature heat pumps in industrial renewable energy systems. Through the utilization of real-time data and complex computer modeling techniques, our proposed digital twin model seamlessly presents a comprehensive perspective on energy flows. This approach identifies inefficiencies and delivers practical insights to mitigate waste. The incorporation of this approach into pre-existing ecoconscious renewable energy systems has the potential to greatly enhance the effectiveness, predictability, and long-term viability of industrial processes. The empirical findings, obtained from multiple case studies conducted in industrial settings, provide evidence of the potential benefits in terms of energy waste reduction, and maximize the durability of systems. The results of our initial studies provide a foundation for the utilization of digital twin technologies in the field of industrial renewable energy systems optimization, representing a significant advancement towards a more environmentally sustainable industrial landscape.
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| 2. |
- Campanella, Gianluca, et al.
(författare)
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Epigenome-wide association study of adiposity and future risk of obesity-related diseases
- 2018
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Ingår i: International Journal of Obesity. - : Nature Publishing Group. - 0307-0565 .- 1476-5497. ; 42:12, s. 2022-2035
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Tidskriftsartikel (refereegranskat)abstract
- Background: Obesity is an established risk factor for several common chronic diseases such as breast and colorectal cancer, metabolic and cardiovascular diseases; however, the biological basis for these relationships is not fully understood. To explore the association of obesity with these conditions, we investigated peripheral blood leucocyte (PBL) DNA methylation markers for adiposity and their contribution to risk of incident breast and colorectal cancer and myocardial infarction.Methods: DNA methylation profiles (Illumina Infinium® HumanMethylation450 BeadChip) from 1941 individuals from four population-based European cohorts were analysed in relation to body mass index, waist circumference, waist-hip and waistheight ratio within a meta-analytical framework. In a subset of these individuals, data on genome-wide gene expression level, biomarkers of glucose and lipid metabolism were also available. Validation of methylation markers associated with all adiposity measures was performed in 358 individuals. Finally, we investigated the association of obesity-related methylation marks with breast, colorectal cancer and myocardial infarction within relevant subsets of the discovery population.Results: We identified 40 CpG loci with methylation levels associated with at least one adiposity measure. Of these, one CpG locus (cg06500161) in ABCG1 was associated with all four adiposity measures (P=9.07×10−8 to 3.27×10−18) and lower transcriptional activity of the full-length isoform of ABCG1 (P=6.00×10−7), higher triglyceride levels (P=5.37×10−9) and higher triglycerides-to-HDL cholesterol ratio (P=1.03×10−10). Of the 40 informative and obesity-related CpG loci, two (in IL2RB and FGF18) were significantly associated with colorectal cancer (inversely, P<1.6×10−3) and one intergenic locus on chromosome 1 was inversely associated with myocardial infarction (P<1.25×10−3), independently of obesity and established risk factors.Conclusion: Our results suggest that epigenetic changes, in particular altered DNA methylation patterns, may be an intermediate biomarker at the intersection of obesity and obesity-related diseases, and could offer clues as to underlying biological mechanisms.
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| 3. |
- Guccione, Salvatore, et al.
(författare)
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Optimum Coupling of Thermal Energy Storage and Power Cycles
- 2023
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Ingår i: Proceedings of ASME Turbo Expo 2023. - : American Society of Mechanical Engineers (ASME).
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Konferensbidrag (refereegranskat)abstract
- The present work proposes a methodology that enables decision-making in selecting the adequate power cycle and Thermal Energy Storage (TES) type for a wide range of operating temperatures between 380 and 1200 °C. A broad spectrum of power block configurations has been explored including steam Rankine, gas turbine, supercritical CO2, (sCO2) combined gas turbine with Rankine, and combined gas turbine with sCO2. The study also evaluated molten salt, particle, and air packed bed TES to identify the most cost-effective power cycle and TES combination. A techno-economic optimization has been conducted aimed at minimizing the Levelized Cost of Storage (LCOS) for different plant capacities and charging costs. Results show that coupling of a sCO2 power block with recompression and intercooling with a particle TES is the most cost-effective solution for a 100 MWe plant with 12 hours of storage and a charging cost of 50 EUR/MWh. This achieved an LCOS value of 154.7 EUR/MWh at 750 °C with a 200 °C temperature difference. Particle-based energy storage is the most cost-effective option for a wide range of temperature combinations, while an intercooled sCO2 power block with an air-packed bed TES should be preferred when electricity is free, and storage represents a significant portion of the capital cost. Molten salt TES is the optimal choice provided that the design temperatures align with the limitations of the salts.
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| 4. |
- Guccione, Salvatore, et al.
(författare)
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Techno-Economic Optimization of a Hybrid PV-CSP Plant With Molten Salt Thermal Energy Storage and Supercritical CO2 Brayton Power Cycle
- 2022
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Ingår i: Proceedings of the ASME Turbo Expo. - : ASME International.
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Konferensbidrag (refereegranskat)abstract
- High-efficient supercritical CO2 (sCO2) power blocks and the hybridization with solar photovoltaic (PV) plants have been identified as two viable solutions to enhance the economic competitiveness of Concentrating Solar Power (CSP) plants. This work introduces an innovative hybrid PV-CSP system layout with molten salt thermal energy storage and a sCO2 power block. An active hybridization has been proposed employing a molten salt electric heater that allows storing the excess PV production as thermal energy. The scalability of the plant has been investigated using size-dependent cost functions and introducing a novel methodology for scaling the sCO2 turbomachinery efficiencies. The conducted techno-economic optimizations show that the proposed hybrid PV-CSP plants can be cost-competitive. For a European solar resource location - 1900 kWh/(m2yr) - Levelized Cost of Electricity (LCOE) values lower than 66 EUR/MWh and capacity factors higher than 70 % can be achieved at 100 MWe. For a high-irradiance location - 3400 kWh/(m2yr) - a capacity factor of 85 % and a LCOE of 46 EUR/MWh have been found for the same scale. The selection of the sCO2 power cycle has a marginal impact on these results so that a simple recuperated cycle can yield similar LCOEs as the recompressed, reheated, and intercooled layouts. For smaller scales, systems with large gaps between the PV and CSP capacities are preferred, laying the optimal conditions for the electric heater integration with utilization factors up to 21 %.
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| 5. |
- Guccione, Salvatore, et al.
(författare)
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Thermodynamic Analysis of a Hybrid PV-Particle Based sCO2 Concentrating Solar Power Plant
- 2023
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Ingår i: AIP Conference Proceedings. - : AIP Publishing.
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Konferensbidrag (refereegranskat)abstract
- The present work performs a thermodynamic analysis of a hybrid CSP – PV plant characterized by a particle tower CSP running a supercritical CO2 power unit and a PV field. The two plants are hybridized by employing a particle electrical heater that allows to store the electricity produced in excess by the PV field as thermal energy in the CSP storage. The PV production is compensated by the CSP plant to achieve the maximum power that can be injected into the grid (25 MW). The main key performance indicators considered in this analysis are the capacity factor, the share of energy wasted, the annual energy yield, the electric heater utilization factor, and the share of TES charged by the electric heater. The influence of the plant solar multiple, storage size, PV nominal size, electric heater efficiency, and electric heater capacity has been assessed through different sensitivity analyses. The results show that it is worth hybridizing the system, indeed the solar power plant operates during summer continuously day and night, exploiting the advantages of the two technologies, while limiting their drawbacks. Plant configurations leading to a capacity factor higher than 81% with a share of energy wasted limited to 5% can be identified. The electric heater capacity and efficiency are shown to be highly important parameters, highlighting the need for further component development.
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| 6. |
- Shamsi, Syed Safeer Mehdi, et al.
(författare)
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Sco2 Based Pumped Heat Thermal Energy Storage Systems Valorizing Industrial Waste Heat Recovery : A Techno-Economic Analysis Of The Role Of High Temperature Tes
- 2023
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Ingår i: Proceedings Of Asme Turbo Expo 2023. - : ASME International. - 9780791886991
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Konferensbidrag (refereegranskat)abstract
- In the current renewable energy dominated power system, as power production is becoming more and more unpredictable, it would be important to act at two levels: integrating relevant power/energy capacity of energy storage and making demand more controllable. At this purpose, acting on industrial energy demand via integration of energy storage and electrification of local processes, could provide a significant contribution. At the same time, waste heat recovery (WHR) is quite a consolidated industrial practise. Nevertheless, WH valorisation is usually performed via bottoming cycles, such as steam, ORC or supercritical CO2 (sCO(2)) power cycles. The development of thermo-mechanical storages to be installed at industrial level, can contribute in this direction through the use of traditional technologies (rotating machinery) employed in power plants as well as in Waste-heat-to-power (WH2P) plants. This paper presents a thermo-economic analysis of Pumped Thermal Energy Storages (PTES) for sCO(2) cycles, comparing market available thermal energy storage materials for different temperature range of operation. The proposed system is purposefully designed to exploit the waste heat sources for the temperature ranges of 150-400 degrees C, difficult to exploit for WH2P solutions and rarely addressed in literature so far. The use of sCO(2) enhances the techno-economic features of these systems, the independent charging and discharging system proposed in this study can also provide a keen sense of flexibility especially for the upscaling of a PTES plant to reach an equal grid flexibility power for charging and discharging. At the same time, the valorisation of low temperature waste heat enables industries to enhance their energy efficiency, limit their operational costs and environmental impact, whilst becoming an active part in the regulation of the grid. At this purpose optimal system configurations and dispatch strategies are identified based on typical load curves of specific EU markets. Starting from an identified reference case (a cement production plant with WH temperature to be valorized around 330 degrees C), different PTES cycle layouts and TES technological solutions are compared on a techno-economic basis. The waste heat integration to the PTES system has been found to add satisfactory value in terms of RTE. On the other hand, it proves to be an optimal use case of waste heat valorisation than traditional waste heat to power cycles when compared in terms of exergy, capital cost and dispatchability in ever increasing RES penetration scenarios. The identification of the most optimal TES however is driven by economic factors too as presented in CAPEX and dispatchability analysis.
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| 7. |
- Trevisan, Silvia, et al.
(författare)
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A high-temperature thermal stability and optical property study of inorganic coatings on ceramic particles for potential thermal energy storage applications
- 2022
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 239
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic-based packed bed solutions are becoming more common in the energy fields as both thermal energy storage and heat exchanger. Such solutions are usually designed for the working temperature ranges above600 ◦C, thus thermal radiation becomes significant and even acts as the dominant heat transfer mechanism. Therefore, applying high-temperature coatings with different thermal properties could be an efficient way in enhancing the performance of these applications. In this work, the high-temperature long residency and cyclic thermal stability of six inorganic coatings applied on a ceramic substrate are investigated. Both qualitative and quantitative assessments are performed. The results show that HIE-Coat 840MX and Pyropaint 634 ZO exhibit excellent thermal stability performance both at high-temperature testing (1000 ◦C) and under thermal cycle testing (400 ◦C–800 ◦C). TiO2 based coatings could be a viable solution if the powder is pre-treated to avoid polymorph transition during the operation. Stainless steel 304 powder-based coating could also be a possible solution, since the adhesive curbs the oxidation and hinders the coating from deterioration. Contrarily, Pyromark2500 and MgO-based coating show different degradation problems that limit their exploitation in high-temperature applications undergoing thermal cycles. The investigated coatings show a wide range of thermal emissivity (between 0.6 and 0.9), with stable or decreasing trends with temperature. This enables a potential20% change of the effective thermal conductivity for the packing structure. This work is a stepping-stone towards further detailed experimental studies on the influence of coatings on various packed bed thermal storage systems, and thus offer a new option in improving the performances of the energy equipment with packed bed systems.
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| 8. |
- Trevisan, Silvia, et al.
(författare)
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A study of metallic coatings on ceramic particles for thermal emissivity control and effective thermal conductivity enhancement in packed bed thermal energy storage
- 2022
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 234
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic particles-based packed bed systems are attracting the interest from various high-temperature applications such as thermal energy storage, nuclear cooling reactors, and catalytic support structures. Considering that these systems work above 600 ◦C, thermal radiation becomes significant or even the major heat transfer mechanism. The use of coatings with different thermal and optical properties could represent a way to tune and enhance the thermodynamic performances of the packed bed systems. In this study, the thermal stability of several metallic (Inconel, Nitinol, and Stainless Steel) based coatings is investigated at both high temperature and cyclic thermal conditions. Consequently, the optical properties and their temperature dependence are measured. The results show that both Nitinol and Stainless Steel coatings have excellent thermal stability at temperatures as high as 1000 ◦C and after multiple thermal cycles. Contrarily, Inconel (particularly 625) based coatings show abundant coating degradation. The investigated coatings also offer a wide range of thermal emissivity (between0.6 and 0.9 in the temperature range of 400–1000 ◦C), and variable trends against increasing temperature. This work is a stepping-stone towards further detailed experimental and modelling studies on the heat transfer enhancement in different ceramic-based packed bed applications through using metallic coatings.
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| 9. |
- Trevisan, Silvia, et al.
(författare)
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Coatings utilization to modify the effective properties of high temperature packed bed thermal energy storage
- 2021
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Ingår i: Applied Thermal Engineering. - : Elsevier. - 1359-4311 .- 1873-5606. ; 185
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature thermal energy storage is becoming more and more important as a key component in concentrating solar power systems and as an economically viable large-scale energy storage solution. Ceramics and natural rocks based packed beds are one of the attracting solutions. For application temperatures above 600 ◦C, radiation heat transfer becomes the dominant heat transfer phenomenon and it greatly influences the performance of thermal storage systems. Coatings with different thermal properties (mainly thermal emissivity and thermal conductivity) could be exploited to modify the effective thermal properties of packed beds. In this work, we present a methodology to account for the thermal effect of a coating layer applied over the pebbles of a packed bed. The influences on the packed bed effective thermal conductivity of several characteristics of the coating material, packed bed arrangement, and filler material are investigated. The results show that low emissivity coatings could reduce the effective thermal conductivity of a rock based packed bed of about 58%, with respect to a similar uncoated solution, already at 800 ◦C. A low emissivity coating could also limit the increase in the thermal effective conductivity from the cold to the hot zone of the storage. Coatings would have a higher influence when applied in packed beds with large size particles, relatively high thermal conductivity of the substrate and void fraction. The application of different coatings, with various thermo-physical properties, in different parts of the storage could modify the effective thermal conductivity distribution and enable a partial control of the thermocline degradation, increasing the storage thermal efficiency.
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| 10. |
- Trevisan, Silvia, et al.
(författare)
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Design optimization of an innovative layered radial-flow high-temperature packed bed thermal energy storage
- 2024
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Ingår i: Journal of Energy Storage. - : Elsevier. - 2352-152X .- 2352-1538. ; 83
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Tidskriftsartikel (refereegranskat)abstract
- The present work introduces an innovative layered radial flow packed-bed thermal energy storage able to provide enhanced thermal and hydrostatic performance, limiting their inherent trade-off. The performance of the proposed packed-bed thermal energy storage concept is modelled, in both thermal and hydrodynamic aspects, via a 1D-two phases numerical approach. Representative storage sizes for industrial applications and laboratory prototype are considered to highlight the potential for scaling and the representativeness of prototyping. Configurations with two and three coaxial layers are also analyzed. The investigation includes a multi-objective optimization of the thermal energy storage design considering a set of main design variables and a set of sensitivity analyses aimed at highlighting the influence of major operational parameters. The results show that the proposed storage geometry can provide simultaneous optimization of both thermal and hydrodynamic performance. The proposed storage unit could attain pressure drop reductions higher than 70 % with respect to uniform radial flow packed bed storage (and higher than 85 % with respect to axial flow units) at the expense of a useful duration reduction lower than 5 %. Industrial scale storage would benefit from low aspect ratios and arrangement with modular units, ensuring enhanced system flexibility and reduced parasitic consumptions thanks to lower pressure losses meanwhile guaranteeing extensive useful durations in both charge and discharge operation. Downscaled prototypes can provide a good representation of the thermal and hydrodynamic behavior of the proposed thermal energy storage solution and a relevant base for validation. This work paves the way for future prototyping and validation of the proposed layered radial flow packed-bed thermal energy storage concept.
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| 11. |
- Trevisan, Silvia, et al.
(författare)
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Experimental Evaluation of a High-Temperature Radial-Flow Packed Bed Thermal Energy Storage under Dynamic Boundary Conditions
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- High-temperature thermal energy storage is recognized to be a key technology to ensure a future fossil-free energy scenario. Packed bed thermal energy storage is an economically viable high-temperature and large-scale energy storage solution. The present work introduces the experimental investigation of an innovative 49.7 kWhth radial-flow type high-temperature packed bed thermal energy storage under dynamic boundary conditions. Various quasi-dynamic air flow rate profiles, representative of different potential applications, have been tested during the charge process to investigate their influence on the thermodynamic performance of the storage. The outlet thermal power during the discharge has been controlled by managing the air flow rate. Short operational cycles have also been performed. The results show that dynamic boundary conditions can lead to a thermal efficiency reduction between 0.5 and 5 % with respect to static conditions. A control of the air mass flow rate could be an efficient strategy to stabilize the thermal power output during the discharge while minimizing peaks in the pressure drop. This work testifies that specific dynamic boundary conditions should be included during the thermal storage design process since they could largely affect the unit thermodynamic performance and potential scale-up. If no specific dynamic profiles are available during the packed bed storage design stage, it is suggested to consider average air mass flow rate to guarantee limited efficiency reduction.
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| 12. |
- Trevisan, Silvia, et al.
(författare)
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Experimental evaluation of a high-temperature radial-flow packed bed thermal energy storage under dynamic mass flow rate
- 2022
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Ingår i: Journal of Energy Storage. - : Elsevier BV. - 2352-152X .- 2352-1538. ; 54, s. 105236-
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature thermal energy storage is recognized to be a key technology to ensure future sustainable energy generation. Packed bed thermal energy storage is a cost-competitive large-scale energy storage solution. The present work introduces the experimental investigation of an innovative 49.7 kWh(th) radial-flow type high-temperature packed bed thermal energy storage under dynamic mass flow rates. Various dynamic air flow rate profiles, representative of different potential applications, have been tested during the charging process to investigate their influence on the thermodynamic performance of the storage. The outlet thermal power during the discharge has been controlled by managing the air flow rate. Short operational cycles have also been performed. The results show that dynamic mass flow rates can lead to a thermal efficiency reduction between 0.5 % and 5 % with respect to static conditions. Controlling the air mass flow rate could be an efficient strategy to stabilize the thermal power output during the discharge while minimizing peaks in the pressure drop. This work testifies that specific dynamic boundary conditions should be included during the thermal storage design process since they could largely affect the unit thermodynamic performance and potential scale-up. If no specific dynamic profiles are available during the packed bed storage design stage, it is suggested to consider typical dynamic profiles of the air mass flow rate to guarantee limited efficiency reduction during operation.
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| 13. |
- Trevisan, Silvia, et al.
(författare)
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Experimental evaluation of an innovative radial-flow high-temperature packed bed thermal energy storage
- 2022
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 311
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature packed-bed thermal energy storage represents an economically viable large-scale energy storage solution for a future fossil-free energy scenario. The present work introduces first-of-a-kind experimental setup of a radial packed-bed TES, and its performance assessment based on experimental investigations. The storage performance is analyzed based on a set of dimensionless criteria and indicators. The laboratory-scale prototype has an energy capacity of 49.7 kWhth and working temperatures between 25 ◦C and 700 ◦C with anon-pressurized dry airflow. The influence of different working fluid mass flow rates and inlet temperatures during charge and discharge is assessed. The proposed storage design ensures limited pressure drop, lower than1 mbar, and thermal losses, about 1.11 % during dwell after charging at 700 ◦C until a state of charge of 55.8 %. A maximum overall thermal efficiency of 71.8 % has been recorded and trade-offs between efficiency, thermal uniformity, and thermocline thickness are highlighted. This work testifies that reduced pressure drops are the key advantage of radial-flow packed-bed designs. Thermocline degradation is shown to be the main weak point of this thermal energy storage design.
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| 14. |
- Trevisan, Silvia, et al.
(författare)
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Initial design of a radial-flow high temperature thermal energy storage concept for air-driven CSP systems
- 2019
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Ingår i: AIP Conference Proceedings. - : American Institute of Physics (AIP).
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Konferensbidrag (refereegranskat)abstract
- The present work deals with the initial design and performance evaluation of a novel thermal energy storage concept consisting of a packed bed of rocks with a radial gas flow, suitable for the a generation of air-driven concentrating solar power plants. In doing so, this article also presents a state of the art of most promising packed bed concepts, highlighting their advantages and disadvantages, all considered in the design of the new proposed system. A thermomechanical model of the concept was developed and used in simulations to assess its behavior during both charging and discharging processes, as well as to evaluate the influence of critical design parameters. This same model was used to compare the technical performance of the concept against that of more conventional packed-beds with axial-flow. Results show that the novel concept is able to outperform the other systems by enabling a theoretical reduction of 46% and 50% in radiation losses and pressure drops, respectively, thus calling for future investigations, including an in-depth thermos-mechanical study and life-cycle analysis of the concept prior to building a lab-scale prototype.
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| 15. |
- Trevisan, Silvia, et al.
(författare)
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Laboratory prototype of an innovative radial flow packed bed thermal energy storage
- 2022
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Ingår i: SOLARPACES 2020. - : AIP Publishing.
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Konferensbidrag (refereegranskat)abstract
- This work presents a laboratory scale 50kWhth prototype of an innovative radial flow packed bed thermal energy storage. The proposed storage has an inward radial heat transfer fluid flow during charge and a reverted fluid flow, by means of a valve arrangement, during discharge. The storage unit is equipped with differential pressure gauges, mass flow controller and 50?K-thermocouples to accurately measure the thermodynamic behavior of the unit. In order to assess the performance of the proposed thermal energy storage design two specific indicators have been introduced and defined, namely: the temperature uniformity, and the hydrodynamic uniformity. The results of preliminary CFD studies show a maximum temperature deviation of 20°C along the storage axial direction and uniformity indexes higher than 90%.
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| 16. |
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| 17. |
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| 18. |
- Trevisan, Silvia, et al.
(författare)
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Packed bed thermal energy storage: A novel design methodology including quasi-dynamic boundary conditions and techno-economic optimization
- 2021
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Ingår i: Journal of Energy Storage. - : Elsevier BV. - 2352-152X .- 2352-1538.
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Tidskriftsartikel (refereegranskat)abstract
- High temperature thermal energy storages are becoming more and more important as a key component in concentrating solar power plants. Packed bed storages represent an economically viable large scale energy storage solution. The present work deals with the analysis and optimization of a packed bed thermal energy storage. The influence of quasi-dynamic boundary conditions on the storage thermodynamic performance is evaluated. The Levelized Cost of Storage is innovatively applied to thermal energy storage design. A complete methodology to design packed bed thermal energy storage is proposed. In doing so, a comprehensive multi-objective optimization of an industrial scale packed bed is performed. The results show that quasi-dynamic boundary conditions lead to a reduction of around 5% of the storage thermal efficiency. Contrarily, the effect of the investigated design variables over the TES LCoS optimization is only slightly influenced by quasi-dynamic boundary conditions. Aspect ratio between 0.75 and 0.9 would maximize the storage thermal efficiency, while low preliminary efficiency around 0.47 would minimize the Levelized Cost of Storage. This work testifies that quasi-dynamic boundary conditions should be taken into considerations when optimizing thermal energy storage. The Levelized Cost of Storage could be also considered as a more reliable performance indicator for packed bed thermal energy storage, as it is less dependent on variable boundary conditions.
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| 19. |
- Trevisan, Silvia, et al.
(författare)
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Power-to-heat for the industrial sector: Techno-economic assessment of a molten salt-based solution
- 2022
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 272
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Tidskriftsartikel (refereegranskat)abstract
- The industrial sector is a major source of wealth, producing about one-quarter of the global gross product. However, industry is also a major emitter of CO2 and it represents a key challenge towards achieving the worldwide CO2 emission reduction targets. Nowadays, about 22 % of the overall energy demand is heating for the industrial sector, generating about 40 % of the global CO2 emissions. Solutions to decarbonize the industrial sector are needed. This work presents the techno-economic assessment of molten salt based power-to-heat solution aiming at decarbonizing the industrial sector, requiring medium temperature heat (150–450 ◦C). The system is studied under different electric markets considering electricity prices of 2021, future electricity market price modifications are assessed via sensitivity analyses. Dispatch strategies and system sizing are identified to ensure optimal techno-economic performance. The main performance indicators investigated are the Levelized cost of heat, the operational expenditure, and the attainable savings with respect to traditional solutions. The system scalability and sizing criteria are investigated accounting for different typical industrial load profile curves and nominal thermal power demands. The results highlight that nominal levelized cost of heat as low as55 €/MWhth are attainable in cheap electricity markets (i.e. Denmark) and 80 €/MWhth in more expensive scenarios (i.e. United Kingdom). The proposed system can provide operational cost savings between 0.5 and 3M€/y against traditional non-flexible electric boilers and even wider benefits if fossil fuels-based boilers are considered. Future electricity markets, subjected to higher renewable penetration causing cheaper average electricity prices and higher price volatility, could lead to further reductions of the levelized cost of heat of more than 20 % achieving values below 45 €/MWhth in markets such as Denmark. This study sets the ground for further power-to-heat techno-economic investigations addressing different industrial sectors and identifies main system design strategies.
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| 20. |
- Trevisan, Silvia, et al.
(författare)
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Preliminary assessment of integration of a packed bed thermal energy storage in a Stirling - CSP system
- 2019
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Ingår i: SolarPACES 2018. - : American Institute of Physics (AIP).
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Konferensbidrag (refereegranskat)abstract
- The present work deals with the thermodynamic analysis of four different integration schemes for a packed bed thermal energy storage in a Stirling - CSP system. Simplified models for the different systems' configurations have been developed and analyzed in steady and transient working conditions. Particularly, a parallel and serial connection between the power and the storage unit have been compared, showing a trade-off between the contemporaneity of power production and storage and the usefulness of the storage itself accordingly to the working temperature constraints for the power unit. It is shown that a closed parallel system configuration is the most promising solution as it allows for a longer production during night time and an higher net energy production, it is therefore worth of further investigations.
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| 21. |
- Trevisan, Silvia, 1993-
(författare)
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Renewable Heat on Demand : High-temperature thermal energy storage: a comprehensive study from material investigation to system analysis via innovative component design
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High-temperature thermal energy storage could enable widespread exploitation of renewable energy sources, providing the required energy flexibility. Technology and component development is needed to enhance the storage thermo-dynamic performance, and identify key design features. Similarly, system-level integration studies are required to fully understand the techno-economic potential of high-temperature thermal energy storage as integrated into different energy systems. This research work focuses on the development of an innovative packed bed high-temperature thermal energy storage and a multi-level investigation of the potential of this technology. The integration and techno-economic performance of a packed bed thermal energy storage have been studied focusing primarily on its application within concentrating solar power plants. Numerical studies and experimental tests have been conducted assessing the suitability of various coatings to optimize the heat transfer in high-temperature packed beds. A comprehensive design of an innovative packed bed thermal energy storage prototype and its experimental evaluation have been presented. Adapted numerical models have also been validated based on the experimental results, providing the ground for further technology development.The outcomes of this research work show that packed bed thermal energy storage could be a key component in air-driven concentrating solar powerplants, granting high capacity factor while limiting the capital costs. The designed radial flow packed bed storage showed thermal efficiency of about72 % and extremely low-pressure drops. Thermocline degradation control strategies and proper packing have been highlighted as key aspects to target for further development. This research also highlights that accurate boundary conditions should be accounted for when designing packed bed thermal energy storage. Innovative figures of merit, such as the Levelized Cost ofStorage, should be included in the design process. The outcomes of this work show also that coatings could be exploited to modify the particle surface properties while optimizing the heat transfer within packed bed units. In particular, high emissivity coatings could enhance the effective thermal conductivity, while coatings with low thermal emissivity could be exploited as a form of passive thermocline control. Finally, this work testifies that high temperature packed bed could represent a techno-economically valuable energy storage solution. Optimized packed bed designs and their system integration could enable higher renewable penetration, as well as the recovery of a large amount of waste heat from the hard-to-abate and energy-intensive industrial sector.
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| 22. |
- Trevisan, Silvia, et al.
(författare)
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Supercritical CO2 Brayton Power Cycle for CSP With Packed Bed TES Integration and Cost Benchmark Evaluation
- 2019
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Ingår i: Proceedings ASME 2019 Power Conference. - : American Society of Mechanical Engineers (ASME). - 9780791859100
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Konferensbidrag (refereegranskat)abstract
- The present work introduces an indirect supercritical CO2 - air driven concentrated solar plant with a packed bed thermal energy storage. The proposed plant design enables a supercritical CO2 turbine inlet temperature of 800 degrees C, overcoming the temperature limits imposed by the use of solar molten salts as primary heat transfer fluid. Furthermore, the packed bed thermal energy storage permits the decoupling between thermal power collection from the sun and electricity generation. Besides, the thermal energy storage unit grants operational flexibility and enlarges the plant capacity factor, making it as available as a conventional coal facility. A transient thermodynamic model of the integrated concentrating solar plant, including receiver, thermal energy storage, intermediate heat exchangers and supercritical CO2 power cycle has been developed. This same model has been used to evaluate the thermodynamic performance of the proposed plant design over a complete year. A similar model has been implemented to simulate a supercritical CO2 plant driven by a more traditional solar molten salt loop. A comparison of the thermodynamic performance of the two plant designs has been performed. A complete economic model has been developed in order to evaluate the economic viability of the proposed plant. Furthermore, a multi-objective optimization have been executed in order to assess the influence of the thermal energy storage size, supercritical CO2 turbine inlet temperature and plant solar multiple on the key performance indicators. Results show that the proposed indirect supercritical CO2 air driven with a packed bed thermal energy storage concentrated solar plant leads to improved thermo-economic performance with respect to the molten salts driven design. Enhancements in the power cycle efficiency and in the overall electricity production can be achieved, with a consequent reduction in the levelized cost of electricity. Particularly, for a design net electrical power production of 10MWe a minimum levelized cost of electricity has been calculated at 89.4 $/MWh for a thermal energy storage capacity of 13.9 hours at full load and a plant solar multiple of 2.47 corresponding to a capital investment of about 73.4 M$.
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| 23. |
- Trevisan, Silvia, et al.
(författare)
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Techno-economic analysis of a solar hybrid combined cycle power plant integrated with a packed bed storage at gas turbine exhaust
- 2020
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Ingår i: AIP Conference Proceedings. - : AIP Publishing.
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Konferensbidrag (refereegranskat)abstract
- The present work performs a techno-economic analysis of an innovative solar-hybrid combined cycle composed of a topping gas turbine coupled to a bottoming packed bed thermal energy storage at the gas turbine exhaust, which runs in parallel to a bottoming steam cycle. Plant performances have been evaluated in terms of the capacity factor, the specificCO2 emissions, the capital expenditure, and the Levelised Cost of Electricity. The influence of the combustion chamber outlet temperature, solar multiple and energy storage capacity has been assessed by means of a sensitivity analysis. The present study also compares the previously listed performance against that of conventional molten salt tower ConcentratingSolar Power plants and traditional combined cycle gas turbine power plants with equivalent installed capacities and load factors. The results show that it is worth hybridizing the system, particularly at high combustion chamber outlet temperature, large storage size and solar multiple. Furthermore, plant configurations leading to a Levelised Cost of Electricity lower than 110 $/MWh can be achieved for a capacity factor of about 60%. Under these working conditions, the proposed configuration would be only 1.66 times more costly than an equivalent size CCGT. At the same time, it would yield less than half of the emissions of the latter. Simultaneously, the proposed layout is considerably cheaper than an equivalent molten salt Concentrating Solar Power plant.
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| 24. |
- Trevisan, Silvia, et al.
(författare)
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Techno-economic analysis of an innovative purely solar-driven combined cycle system based on packed bed TES technology
- 2020
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Ingår i: AIP Conference Proceedings. - : AIP Publishing.
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Konferensbidrag (refereegranskat)abstract
- The present work performs a techno-economic analysis of a purely solar driven combined cycle composed of a solar air receiver directly connected to a topping gas turbine coupled to a bottoming packed bed thermal energy storage atthe gas turbine exhaust, which runs in parallel to a bottoming steam cycle. Capacity factor, capital expenditure, and Levelized Cost of Electricity have been considered to assess the plant performance. A sensitivity analysis has been performed in order to understand the influence of solar multiple, energy storage capacity and gas turbine expansion ratio over the plant key performance indicators. The results show that the studied solar driven combined cycle is more costly than conventional ones, and therefore it leads to higher Levelized Cost of Electricity. However, it enables a complete reduction of CO2 emissions and increased flexibility in the system with the help of the introduction of an intermediate packet bed thermal energy storage. Furthermore, large solar multiple, medium storage capacity and complete expansion ratio through the gas turbine enable enhanced system performance. Finally, further works including optimized dispatch algorithms could enable a proper evaluation of the economic profit given by the flexibility offered by the storage unit and by a potential control of the Brayton cycle recuperation level in the modified plant layouts.
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| 25. |
- Trevisan, Silvia, et al.
(författare)
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Techno-economic analysis of hybrid supercritical CO2based molten salt tower CSP-PV
- 2022
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Ingår i: SOLARPACES 2020. - : AIP Publishing.
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Konferensbidrag (refereegranskat)abstract
- The present work performs a techno-economic analysis of a hybrid CSP - PV plant composed of a molten salt tower CSP running a supercritical CO2 power unit and a PV field. The two plants are connected in parallel, behind the meter. The PV unit produces power during daylight. The CSP plant stores thermal energy during the day to enable stable production during cloudy periods and enlarges the plant capacity factor while producing during the night. The plant performances have been evaluated in terms of capacity factor, thermal energy storage utilization factor, capital expenditure, and Levelised Cost of Electricity. The influence of plant solar multiple, storage size, supercritical CO2 nominal size, PV relative nominal size, receiver thermal efficiency, CO2 power unit, and PV cost assumptions has been assessed through different sensitivity analyses. The results show that it is worth hybridizing the system, indeed the PV unit can provide low-cost renewable power during the day, while the CSP unit can provide a cheap storage technology. Plant configurations leading to a Levelised Cost of Electricity lower than 70 $/MWhe can be identified already at relatively low nominal power size, 15 MWe. The receiver thermal efficiency is shown to be a highly important assumption, highlighting the need for further component development.
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| 26. |
- Trevisan, Silvia, et al.
(författare)
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Techno-Economic Assessment of CO2-Based Power to Heat to Power Systems for Industrial Applications
- 2023
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Ingår i: Journal of engineering for gas turbines and power. - : ASME International. - 0742-4795 .- 1528-8919. ; 145:12
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Tidskriftsartikel (refereegranskat)abstract
- The industrial sector is a major source of wealth, producing about one-quarter of the global gross product. However, industry is also a major emitter of CO2 and it represents a key challenge toward achieving the worldwide CO2 emission reduction targets. Nowadays, about 22% of the overall energy demand is heating for the industrial sector, generating about 40% of the global CO2 emissions. Additionally, 30% of the final energy demand of the industrial sector is electricity. Solutions to decarbonize the industrial sector are needed. This work presents the techno-economic assessment of four different molten salts-based power-to-heat-to-heat and power solutions aiming at decarbonizing the industrial sector, requiring medium-temperature heat. The systems are studied under different electric markets. Dispatch strategies and system sizing are identified to ensure optimal techno-economic performance. The main performance indicators investigated are the levelized cost of heat and electricity (LCoH and LCoE), the operational expenditure, and the attainable savings with respect to alternative business-as-usual solutions. The results highlight that the proposed system can be cost-competitive, particularly in markets characterized by low electricity prices and high daily price fluctuations, such as Finland. In these locations, LCoEas low as 100 e/MWh and LCoH lower than 55 e/MWh can be attained by the base system configuration. The introduction of high-temperature heat pumps can provide further reduction of about 50%. This study sets the ground for further power-to-heat-to-heat and power techno-economic investigations addressing different industrial sectors and identifies main system design strategies.
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| 27. |
- Trevisan, Silvia, et al.
(författare)
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Techno-Economic Assessment of CO2 Based Power to Heat to Power Systems for Industrial Applications
- 2023
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Ingår i: Proceedings of ASME Turbo Expo 2023. - : American Society of Mechanical Engineers (ASME).
-
Konferensbidrag (refereegranskat)abstract
- The industrial sector is a major source of wealth, producing about one-quarter of the global gross product. However, industry is also a major emitter of CO2 and it represents a key challenge towards achieving the worldwide CO2 emission reduction targets. Nowadays, about 22 % of the overall energy demand is heating for the industrial sector, generating about 40 % of the global CO2 emissions. Additionally, 30 % of the final energy demand of the industrial sector is electricity. Solutions to decarbonize the industrial sector are needed. This work presents the techno-economic assessment of four different molten salts based power-to-heat-to-heat and power solutions aiming at decarbonizing the industrial sector, requiring medium temperature heat. The systems are studied under different electric markets. Dispatch strategies and system sizing are identified to ensure optimal techno-economic performance. The main performance indicators investigated are the levelized cost of heat and electricity (LCoH and LCoE), the operational expenditure, and the attainable savings with respect to alternative business as usual solutions. The results highlight that the proposed system can be cost-competitive, particularly in markets characterized by low electricity prices and high daily price fluctuations, such as Finland. In these locations LCoE as low as 100 €/MWh and LCoH lower than 55 €/MWh can be attained by the base system configuration. The introduction of high temperature heat pumps can provide further LCoH reduction of about 50 %. This study sets the ground for further power-to-heat-to-heat and power techno-economic investigations addressing different industrial sectors and identifies main system design strategies.
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| 28. |
- Trevisan, Silvia, et al.
(författare)
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Thermo-economic optimization of an air driven supercritical CO2 Braytonpower cycle for concentrating solar power plant with packed bed thermalenergy storage
- 2020
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; , s. 1373-1391
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents an innovative indirect supercritical CO2 – air driven concentrated solar power plant with a packed bed thermal energy storage. High supercritical CO2 turbine inlet temperature can be achieved, avoiding the temperature limitations set by the use of solar molten salts as primary heat transfer fluid. The packed bed thermal energy storage enables the decoupling between solar irradiation collection and electricity production, and it grants operational flexibility while enhancing the plant capacity factor. A quasi steady-state thermo-economic model of the integrated concentrating solar power plant has been developed. The thermo-economic performance of the proposed plant design has been evaluated via multi-objective optimizations and sensitivity analyses. Results show that a Levelized Cost of Electricity of 100 $/MWhe and a capacity factor higher than 50%can be achieved already at a 10 MWe nominal size. Such limited plant size bounds the capital investment and leads to more bankable and easily installable plants. Results also show that larger plants benefit from economy of scale, with a 65 $/MWhe cost identified for a 50 MWe plant. The receiver efficiency is found to be the most influential assumption. A 20% decrease of receiver efficiency would lead to an increase of more than 15% of the Levelized Cost of Electricity. These results show the potential of indirect supercritical CO2 – air driven concentrated solar power plant and highlight the importance of further air receiver development. More validations and verification tests are needed to ensure the system operation during long lifetime.
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| 29. |
- Trevisan, Silvia, et al.
(författare)
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Thermodynamic analysis of a high temperature multi-layered sensible-latent thermal energy storage
- 2020
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Ingår i: AIP Conference Proceedings. - : AIP Publishing.
-
Konferensbidrag (refereegranskat)abstract
- The present work provides a thorough literature review of the main high temperature sensible and latent materials suitable for a multilayered thermal energy storage system to be integrated into innovative concentrated solar power applications. Furthermore, a thermodynamic comparative analysis of six different multilayered packed-bed thermal energy storage configurations, including three selected high-temperature metallic phase change materials (Al-12.2Si, Al-20Si, andCu-Si27-Mg17) is presented. For each multilayered storage configuration, the overall impact of the phase change material layer thickness on the performance has been analyzed. As expected, the major improvements are enabled by the addition of a high-temperature phase change material at the top of the multi-layered thermal energy storage. Indeed, the discharge phase duration could be extended for 2 hours, while the energy output increases by about 5%. Furthermore, the addition of a lower melting temperature phase change material layer below the topping high temperature one grants a further slight energy output enhancement. However, this seems to be not valuable enough when considering the increased level of complexity and costs induced by such a storage unit design. The study confirms that a larger amount of phase change materials leads to a lower discharge efficiency due to a wider temperature difference between the heat transfer fluid and the storing media during phase change. The performed study reveals that the Cu-17Mg-27Si/rock multilayered thermal energy storage is worth continuing exploring, especially in terms of experimental tests to assess possible corrosion issues and different encapsulation and coating solutions that might considerably affect the lifetime of the system. Technoeconomicanalyses should be also performed to assess the economic viability of the integration of multilayered TES systems in innovative concentrated solar power plant layouts.
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| 30. |
- Trevisan, Silvia, et al.
(författare)
-
Thermodynamic Analysis of an Indirect Supercritical CO2 –Air Driven Concentrated Solar Power Plant with a Packed Bed Thermal Energy Storage
- 2020
-
Ingår i: AIP Conference Proceedings. - : American Institute of Physics (AIP).
-
Konferensbidrag (refereegranskat)abstract
- The present work assesses the thermodynamic performance of an indirect supercritical CO2 – air driven concentrated solar plant with a packed bed thermal energy storage. A specific focus has been devoted to the flexibility requirements on both air and supercritical loops, highlighting key limitations and challenges that need to be addressed prior to a fruitful development of the proposed cycles. The introduced plant design enables a supercritical CO2 turbine inlet temperature of 800°C, overcoming the temperature limits imposed by the use of solar molten salts as primary heat transfer fluid. Furthermore, the packed bed thermal energy storage permits the decoupling between thermal power collection from the sun and electricity generation. Besides, it grants operational flexibility and enlarges the plant capacity factor. Results show that the proposed indirect supercritical CO2 – air driven with a packed bed thermal energy storage concentrated solar plant leads to improved thermodynamic performance with respect to the molten salts driven design, particularly when working at high temperature, above molten salts limit. Enhancements in the power cycle efficiency and in the overall electricity production can be achieved, with a consequent increase of the capacity factor. Furthermore, the proposed system seems viable for the coupling with other power sources as PVs or secondary, low temperature, power cycles.
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| 31. |
- Wang, Wujun, 1984-, et al.
(författare)
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A dual-flow choked nozzle based precise pressure controller for high-temperature gas systems
- 2021
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Ingår i: Measurement. - : Elsevier BV. - 0263-2241 .- 1873-412X. ; 184
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Tidskriftsartikel (refereegranskat)abstract
- A novel dual-flow choked nozzle based pressure controller is developed to achieve high-precision pressure control. The primary air flow is mainly used for offering the required mass flow to the test section, and the secondary air flow is used for regulating the total mass flow through the choked nozzle to achieve required pressure levels. The test results show that the precision of the stabilization of the pressure can reach +/- 0.005 bar for cold-state environments with air flow at ambient temperature, and +/- 0.015 bar for hot-state environments with air flow temperature in the range of 797.1-931.5 degrees C. Besides, this pressure controller has fast response. A new pressure steady state can be reached within 23.1 s for air flow at ambient temperature and 70 s for hightemperature scenario. Since no moving component exposed to the high-temperature air flow, it is very suitable for the pressurized test rigs with extremely high-temperature gas flow.
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| 32. |
- Wang, Wujun, 1984-, et al.
(författare)
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Solar selective reflector materials: Another option for enhancing the efficiency of the high-temperature solar receivers/reactors
- 2021
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248. ; 224
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Tidskriftsartikel (refereegranskat)abstract
- The cavity wall is an important part of a cavity receiver in determining the receiver efficiency. Using solar selective reflector (SSR) materials with low solar absorptivity and high thermal emissivity for the cavity wall design is one efficient way to improve the receiver efficiency. In this work, we present a systematic study of the optical and high-temperature stability performances of six different SSR materials: one refractory ceramic fiber-based substrate material (Fiberfrax 140) and five metallic oxide coatings which are prepared by mixing metallic oxide powders of alumina, magnesium oxide and titanium dioxide with commercial inorganic adhesives. The thermal stability was studied by heating up and keeping the six candidate materials in atmospheric conditions at a temperature of 1250 ◦C for 200 h. The spectrum of hemispherical reflectance in the spectrum band 0.25–25 μmwas measured for analyzing the optical performance of the candidate materials. The obtained results show that all the six materials studied have good solar selective reflection characteristics, i.e, low solar absorptivity and relatively high thermal emissivity. Especially, the alumina-coated substrate material shows excellent performances both for thermal stability and solar selective reflection. The solar reflectivity can reach 94.6%.
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| 33. |
- Xu, Tianhao, et al.
(författare)
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Experimental and Numerical Investigation of a Latent Heat Thermal Energy Storage Unit with Ellipsoidal Macro-encapsulation
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Annan publikation (populärvet., debatt m.m.)abstract
- Experimental and Numerical Investigation of a Latent Heat Thermal Energy Storage Unit with Ellipsoidal Macro-encapsulationTianhao Xu, Emma Nyholm Humire, Silvia Trevisan, Monika Ignatowicz, Samer Sawalha, Justin NW Chiu*Department of Energy Technology, KTH Royal Institute of Technology, 100 44, Stockholm, SwedenAbstractIn this paper, a novel type of macro-encapsulated phase change material (PCM)shaped in ellipsoidis investigated on a component scale.The encapsulated PCM is a paraffin-based commercial material (ATP60); differential scanning calorimetry and transient plane source method are used to measure the thermo-physical properties of the PCM. A numerical model and a 0.382 m3latent heat thermal energy storage (LHTES) prototype have been built and experimentally characterized. The temperature measurements indicate that thermocline is retainedin the packed bed region. The charge/discharge can be accelerated by65% with20 K increase intemperature difference between the phase-change temperature and heat transfer fluid (HTF)inlet temperature. Increasing HTF inlet flowrate from 0.15 m3/h (Re=77) to 0.5 m3/h (Re=256) shortenscompletion time of charge by51%. Furthermore, a one-dimensional packed bed using source based enthalpy method was constructed and validatedwithin6.6% errorfor aReynolds numberof 90 to 922. Compared with a conventional cylindrical PCM capsule, the ellipsoidal encapsulation shows60% increase in discharge speed but 23%lower storage capacity. This work demonstrates a combined experimental and numerical characterization approach for a novel ellipsoidal PCM encapsulationgeometry.
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| 34. |
- Xu, Tianhao, et al.
(författare)
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Experimental and numerical investigation of a latent heat thermal energy storage unit with ellipsoidal macro-encapsulation
- 2022
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 238
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates ellipsoid-shaped macro-encapsulated phase change material (PCM) on a component scale. The selected PCM is a paraffin-based commercial material, namely ATP60; differential scanning calorimetry and transient plane source method are used to measure ATP60's thermo-physical properties. A 0.382 m(3) latent heat thermal energy storage (LHTES) component has been built and experimentally characterized. The temperature measurement results indicate that a thermocline was retained in the packed bed region during charging/discharging processes. The experimental characterization shows that increasing the temperature difference between the heat transfer fluid (HTF) inlet temperature and phase-change temperature by 20 K can shorten the completion time of discharge by 65%, and increasing HTF inlet flowrate from 0.15 m(3)/h (Re = 77) to 0.5 m(3)/h (Re = 256) can shorten the completion time of charge by 51%. Furthermore, a one-dimensional packed bed model using source-based enthalpy method was developed and validated by comparison to experimental results, showing discrepancies in the accumulated storage capacity within 6.6% between simulation and experiment when the Reynolds number of the HTF inlet flow ranges between 90 and 922. Compared with a conventional capsule shaped in 69-mm-diameter and 750-mm-long cylinders, the ellipsoidal capsule shows 60% less completion time of discharge but 23% lower storage capacity. Overall, this work demonstrates a combined experimental and numerical characterization approach for applying novel macro-encapsulated PCM geometries for heating-oriented LHTES.
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