The Experts below are selected from a list of 705 Experts worldwide ranked by ideXlab platform
Suresh V Garimella - One of the best experts on this subject based on the ideXlab platform.
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Economic Optimization of a Concentrating Solar Power Plant With Molten-Salt Thermocline Storage
2020Co-Authors: Scott M Flueckiger, Brian D Iverson, Suresh V GarimellaAbstract:System-level simulation of a molten-salt thermocline tank is undertaken in response to year-long historical weather data and corresponding plant control. Such a simulation is enabled by combining a finite-volume model of the tank that includes a sufficiently faithful representation at low computation cost with a system-level power tower plant model. Annual plant performance of a 100 MW e molten-salt power tower plant is optimized as a function of the thermocline tank size and the plant solar multiple (SM). The effectiveness of the thermocline tank in storing and supplying hot molten salt to the power plant is found to exceed 99% over a year of operation, independent of tank size. The electrical output of the plant is characterized by its capacity factor (CF) over the year, which increases with solar multiple and thermocline tank size albeit with diminishing returns. The economic performance of the plant is characterized with a levelized cost of electricity (LCOE) metric. A previous study conducted by the authors applied a simplified cost metric for plant performance. The current study applies a more comprehensive financial approach and observes a minimum cost of 12.2 ¢/kWh e with a solar multiple of 3 and a thermocline tank storage capacity of 16 h. While the thermocline tank concept is viable and economically feasible, additional plant improvements beyond those pertaining to storage are necessary to achieve grid parity with fossil fuels
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short and long term sensitivity of lab scale thermocline based thermal storage to flow disturbances
Applied Thermal Engineering, 2016Co-Authors: Sandeep Hatte, Suresh V Garimella, Carolina Mirahernandez, S Advaith, Aashay Tinaikar, Utpal Kumar Chetia, K V Manu, K Chattopadhyay, Justin A Weibel, Vinod SrinivasanAbstract:Molten-salt thermocline-based systems are a low-cost option for single-tank thermal energy storage in concentrated solar power plants. Due to the high variability in solar energy availability, these energy storage devices are subject to transient heat loads during charging that can affect the storage efficiency. Numerical simulations were conducted to analyze the stability characteristics of a lab-scale thermocline tank subject to a flow disturbance during charging under different operating temperatures. The charging process was first simulated at a constant Reynolds number for three different Atwood numbers; a stably stratified fluid layer develops inside the storage tank in all cases. A flow disturbance was then introduced at the inlet of the stratified thermocline tank by inserting colder fluid for a short period of time. The disturbance interacts with the thermocline and causes oscillations and mixing. The thermocline oscillations are under-damped and lead to an increase in thermocline region thickness. The transient behavior of the thermocline and the decay rate in its oscillations were analyzed; the damping time depends on the Atwood number. The persistence of flow disturbance effects during long-term cyclical operation was also investigated. Several charge/discharge cycles were simulated at constant Reynolds number to obtain a time-periodic thermal response for each Atwood number. The characteristic flow disturbance was introduced at the inlet during a single charging process, and the thermocline region was observed during several subsequent charge/discharge cycles to assess the long-term temporal attenuation of the disturbance. The thermocline almost fully recovers to the time-periodic behavior after a single cycle. (C) 2016 Elsevier Ltd. All rights reserved.
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cyclic operation of molten salt thermal energy storage in Thermoclines for solar power plants
Applied Energy, 2013Co-Authors: Zhen Yang, Suresh V GarimellaAbstract:Abstract The cyclic operation of molten-salt thermal energy storage Thermoclines for solar thermal power plants is systematically investigated. A comprehensive, two-temperature model is first developed for the cyclic operation of a thermocline operating with a commercially available molten salt as the heat transfer fluid and quartzite rock as the filler. Volume-averaged mass and momentum equations are employed, with the Brinkman–Forchheimer extension to the Darcy law used to model the porous-medium resistance. Energy equations for the molten salt and the filler are coupled by an interstitial Nusselt number representing the heat transfer between the phases. A finite-volume approach is employed to solve the governing equations. The model is validated against experiments from the literature and then used to systematically study the cyclic behavior of the thermocline thermal storage system. Thermal characteristics including temperature profiles and cycle efficiency are explored. Guidelines are developed for designing the dimensions and molten salt flow rates for solar thermocline systems of different power capacities. The cycle efficiency is found to be improved at smaller melt Reynolds numbers, larger length ratios (molten salt flow distance in a half-cycle to the filler particle diameter) and larger tank heights. The filler particle diameter and the tank volume are found to strongly influence the cycle efficiency.
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molten salt thermal energy storage in Thermoclines under different environmental boundary conditions
Applied Energy, 2010Co-Authors: Zhen Yang, Suresh V GarimellaAbstract:Abstract Operation during the charge and discharge cycles of molten-salt Thermoclines used for solar thermal energy storage depends strongly on the environmental boundary conditions to which the tanks are exposed. A comprehensive model which accounts for thermal transport in the molten-salt heat transfer fluid and the filler material in the tank is developed for exploring the effects of boundary conditions on thermocline performance. Heat loss from the tank under non-adiabatic boundary conditions is found to distort the temperature and salt flow distributions relative to the uniform conditions found in adiabatic Thermoclines; as a result, the outflow temperature drops more rapidly in the former case. Such effects of non-adiabatic boundaries become insignificant at large salt-flow Reynolds numbers. As the Reynolds number increases beyond 250, the discharge efficiency of non-adiabatic Thermoclines approaches that of the adiabatic counterparts. In the case of significant heat loss at the walls, the discharge efficiency of Thermoclines increases with increasing Reynolds number, a trend that is opposite to that in adiabatic Thermoclines.
Thomas Fasquelle - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of a 50 mwe parabolic trough power plant integrating a thermocline storage tank
Energy Conversion and Management, 2018Co-Authors: Thomas Fasquelle, Pierre Neveu, Quentin Falcoz, J F HoffmannAbstract:Abstract A simulation of a 50 MWe power plant with thermocline tank as storage shows that there is no deterioration of the thermocline performance with cycling (successive charges and discharges), because no temperature threshold has to be taken into account during charges. Indeed, the best control strategy when the thermocline outlet fluid temperature increases during charge is defocusing a part of the solar field to avoid the heat transfer fluid overheating. Thus, thermocline tank can be fully charged during summer days. During winter days, if there is not enough energy to perform a full charge, cycling effect does not occur because the remaining energy after partial discharge implies a more important state of charge for the following day. Finally, the comparison between thermocline and two-tank technologies shows that oversizing the thermocline tank by 11% leads to equivalent electricity production, for a lower cost (at least 22.3%).
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a temperature threshold evaluation for thermocline energy storage in concentrated solar power plants
Applied Energy, 2018Co-Authors: Thomas Fasquelle, Pierre Neveu, Quentin Falcoz, J F HoffmannAbstract:Abstract Regarding energy storage in concentrated solar power plants, thermocline technology is considered to be a cost effective but less efficient solution than conventional two-tank. However, thermocline storage charge and discharge are usually stopped when the varying outlet temperature reaches an arbitrarily chosen value. It is shown here that the stop of the thermocline charge depends on the overheating risk in the solar collectors, while the stop of the discharge is defined by the steam generator requirements. As a consequence, the temperature thresholds that must be defined by the experimental constraints are dynamic. Using these dynamic thresholds on an experimental setup comprising a 230 kWh thermocline tank and a 150 kWth parabolic trough solar field led to a charge efficiency of 95.7% and a 93.5% discharge efficiency. Thus, the varying outlet temperature of a thermocline storage system is not an issue when integrated in a concentrated solar power plant.
J F Hoffmann - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of a 50 mwe parabolic trough power plant integrating a thermocline storage tank
Energy Conversion and Management, 2018Co-Authors: Thomas Fasquelle, Pierre Neveu, Quentin Falcoz, J F HoffmannAbstract:Abstract A simulation of a 50 MWe power plant with thermocline tank as storage shows that there is no deterioration of the thermocline performance with cycling (successive charges and discharges), because no temperature threshold has to be taken into account during charges. Indeed, the best control strategy when the thermocline outlet fluid temperature increases during charge is defocusing a part of the solar field to avoid the heat transfer fluid overheating. Thus, thermocline tank can be fully charged during summer days. During winter days, if there is not enough energy to perform a full charge, cycling effect does not occur because the remaining energy after partial discharge implies a more important state of charge for the following day. Finally, the comparison between thermocline and two-tank technologies shows that oversizing the thermocline tank by 11% leads to equivalent electricity production, for a lower cost (at least 22.3%).
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a temperature threshold evaluation for thermocline energy storage in concentrated solar power plants
Applied Energy, 2018Co-Authors: Thomas Fasquelle, Pierre Neveu, Quentin Falcoz, J F HoffmannAbstract:Abstract Regarding energy storage in concentrated solar power plants, thermocline technology is considered to be a cost effective but less efficient solution than conventional two-tank. However, thermocline storage charge and discharge are usually stopped when the varying outlet temperature reaches an arbitrarily chosen value. It is shown here that the stop of the thermocline charge depends on the overheating risk in the solar collectors, while the stop of the discharge is defined by the steam generator requirements. As a consequence, the temperature thresholds that must be defined by the experimental constraints are dynamic. Using these dynamic thresholds on an experimental setup comprising a 230 kWh thermocline tank and a 150 kWth parabolic trough solar field led to a charge efficiency of 95.7% and a 93.5% discharge efficiency. Thus, the varying outlet temperature of a thermocline storage system is not an issue when integrated in a concentrated solar power plant.
Quentin Falcoz - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of a 50 mwe parabolic trough power plant integrating a thermocline storage tank
Energy Conversion and Management, 2018Co-Authors: Thomas Fasquelle, Pierre Neveu, Quentin Falcoz, J F HoffmannAbstract:Abstract A simulation of a 50 MWe power plant with thermocline tank as storage shows that there is no deterioration of the thermocline performance with cycling (successive charges and discharges), because no temperature threshold has to be taken into account during charges. Indeed, the best control strategy when the thermocline outlet fluid temperature increases during charge is defocusing a part of the solar field to avoid the heat transfer fluid overheating. Thus, thermocline tank can be fully charged during summer days. During winter days, if there is not enough energy to perform a full charge, cycling effect does not occur because the remaining energy after partial discharge implies a more important state of charge for the following day. Finally, the comparison between thermocline and two-tank technologies shows that oversizing the thermocline tank by 11% leads to equivalent electricity production, for a lower cost (at least 22.3%).
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a temperature threshold evaluation for thermocline energy storage in concentrated solar power plants
Applied Energy, 2018Co-Authors: Thomas Fasquelle, Pierre Neveu, Quentin Falcoz, J F HoffmannAbstract:Abstract Regarding energy storage in concentrated solar power plants, thermocline technology is considered to be a cost effective but less efficient solution than conventional two-tank. However, thermocline storage charge and discharge are usually stopped when the varying outlet temperature reaches an arbitrarily chosen value. It is shown here that the stop of the thermocline charge depends on the overheating risk in the solar collectors, while the stop of the discharge is defined by the steam generator requirements. As a consequence, the temperature thresholds that must be defined by the experimental constraints are dynamic. Using these dynamic thresholds on an experimental setup comprising a 230 kWh thermocline tank and a 150 kWth parabolic trough solar field led to a charge efficiency of 95.7% and a 93.5% discharge efficiency. Thus, the varying outlet temperature of a thermocline storage system is not an issue when integrated in a concentrated solar power plant.
Pierre Neveu - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of a 50 mwe parabolic trough power plant integrating a thermocline storage tank
Energy Conversion and Management, 2018Co-Authors: Thomas Fasquelle, Pierre Neveu, Quentin Falcoz, J F HoffmannAbstract:Abstract A simulation of a 50 MWe power plant with thermocline tank as storage shows that there is no deterioration of the thermocline performance with cycling (successive charges and discharges), because no temperature threshold has to be taken into account during charges. Indeed, the best control strategy when the thermocline outlet fluid temperature increases during charge is defocusing a part of the solar field to avoid the heat transfer fluid overheating. Thus, thermocline tank can be fully charged during summer days. During winter days, if there is not enough energy to perform a full charge, cycling effect does not occur because the remaining energy after partial discharge implies a more important state of charge for the following day. Finally, the comparison between thermocline and two-tank technologies shows that oversizing the thermocline tank by 11% leads to equivalent electricity production, for a lower cost (at least 22.3%).
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a temperature threshold evaluation for thermocline energy storage in concentrated solar power plants
Applied Energy, 2018Co-Authors: Thomas Fasquelle, Pierre Neveu, Quentin Falcoz, J F HoffmannAbstract:Abstract Regarding energy storage in concentrated solar power plants, thermocline technology is considered to be a cost effective but less efficient solution than conventional two-tank. However, thermocline storage charge and discharge are usually stopped when the varying outlet temperature reaches an arbitrarily chosen value. It is shown here that the stop of the thermocline charge depends on the overheating risk in the solar collectors, while the stop of the discharge is defined by the steam generator requirements. As a consequence, the temperature thresholds that must be defined by the experimental constraints are dynamic. Using these dynamic thresholds on an experimental setup comprising a 230 kWh thermocline tank and a 150 kWth parabolic trough solar field led to a charge efficiency of 95.7% and a 93.5% discharge efficiency. Thus, the varying outlet temperature of a thermocline storage system is not an issue when integrated in a concentrated solar power plant.