Alexander S. Fredrickson, A. Pollman, A. Gannon, W. Smith
This paper presents the results of a theoretical analysis of a heat exchanger design for the challenging application of a small-scale modified Linde-Hampson cycle liquid air energy storage system (LAESS). A systems engineering approach was taken to determine the best heat exchanger alternative for incorporation into an existing LAESS. Two primary heat exchanger designs were analyzed and compared: a finned tube heat exchanger (FTHE) design and a printed circuit heat exchanger (PCHE) design. These designs were chosen as alternatives due to the gas-to-gas cooling that occurs in the heat exchanger, and material selection was based on the requirement for the heat exchanger to withstand the cryogenic temperatures required for the system to produce liquid nitrogen. Thermodynamic analysis was conducted using the ε-NTU method and fin theory to determine the dimensional requirements for the finned tube heat exchanger and a trade-off study was conducted to compare the alternatives. Based on the results from the study, the PCHE was the preferred alternative due to an inherent small footprint, comparable cost to manufacture, simple integration into the LAESS and inherent safety features that are critical when working with high pressure systems. Future work will include subsystem and system integration and testing to obtain a consistently functional prototype that produces liquid nitrogen.
{"title":"Selection of a Heat Exchanger for a Small-Scale Liquid Air Energy Storage System","authors":"Alexander S. Fredrickson, A. Pollman, A. Gannon, W. Smith","doi":"10.1115/power2021-60523","DOIUrl":"https://doi.org/10.1115/power2021-60523","url":null,"abstract":"\u0000 This paper presents the results of a theoretical analysis of a heat exchanger design for the challenging application of a small-scale modified Linde-Hampson cycle liquid air energy storage system (LAESS). A systems engineering approach was taken to determine the best heat exchanger alternative for incorporation into an existing LAESS. Two primary heat exchanger designs were analyzed and compared: a finned tube heat exchanger (FTHE) design and a printed circuit heat exchanger (PCHE) design. These designs were chosen as alternatives due to the gas-to-gas cooling that occurs in the heat exchanger, and material selection was based on the requirement for the heat exchanger to withstand the cryogenic temperatures required for the system to produce liquid nitrogen. Thermodynamic analysis was conducted using the ε-NTU method and fin theory to determine the dimensional requirements for the finned tube heat exchanger and a trade-off study was conducted to compare the alternatives. Based on the results from the study, the PCHE was the preferred alternative due to an inherent small footprint, comparable cost to manufacture, simple integration into the LAESS and inherent safety features that are critical when working with high pressure systems. Future work will include subsystem and system integration and testing to obtain a consistently functional prototype that produces liquid nitrogen.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80518750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
André L. S. Andade, O. Venturini, V. Cobas, V. Z. Silva
In order to increase the flexibility and performance of gas turbines, generally their manufacturers and research centers involved in their development are constantly seeking the expansion of their operational envelope as well as their efficiency, making the engine more dynamic, less polluting and able to respond promptly to variations in load demands. An important aspect that should be considered when analyzing these prime movers is the assessment of its behavior under transients due to load changes, which can be accomplished through the development of a detailed, accurate and effective computational model. Considering this scenario, the present work aims to develop a model for the simulation and analysis of the dynamic behavior of stationary gas turbines. The engine considered in this analysis has a nominal capacity of 30.7 MW (ISO conditions) and is composed by a two-spool gas generator and a free power turbine. The model was developed using T-MATS, an integrated Simulink/Matlab toolbox, develop by NASA. The gas turbine was evaluated under both permanent and transient regimes and each one of its component was analyzed individually. The assessment made it possible to determine the engine performance parameters such as efficiency, heat rate and specific fuel consumption and its operational limits (surge limits, stall, turbine inlet temperatures, etc.) under different load conditions and regimes. The results obtained were compared with available field data, and the relative deviations for the considered parameters were all lower than 1%.
{"title":"Modelling and Performance Analysis of Stationary Gas Turbines Operating Under Rotational Speed Transients","authors":"André L. S. Andade, O. Venturini, V. Cobas, V. Z. Silva","doi":"10.1115/power2021-64316","DOIUrl":"https://doi.org/10.1115/power2021-64316","url":null,"abstract":"\u0000 In order to increase the flexibility and performance of gas turbines, generally their manufacturers and research centers involved in their development are constantly seeking the expansion of their operational envelope as well as their efficiency, making the engine more dynamic, less polluting and able to respond promptly to variations in load demands. An important aspect that should be considered when analyzing these prime movers is the assessment of its behavior under transients due to load changes, which can be accomplished through the development of a detailed, accurate and effective computational model. Considering this scenario, the present work aims to develop a model for the simulation and analysis of the dynamic behavior of stationary gas turbines. The engine considered in this analysis has a nominal capacity of 30.7 MW (ISO conditions) and is composed by a two-spool gas generator and a free power turbine. The model was developed using T-MATS, an integrated Simulink/Matlab toolbox, develop by NASA. The gas turbine was evaluated under both permanent and transient regimes and each one of its component was analyzed individually. The assessment made it possible to determine the engine performance parameters such as efficiency, heat rate and specific fuel consumption and its operational limits (surge limits, stall, turbine inlet temperatures, etc.) under different load conditions and regimes. The results obtained were compared with available field data, and the relative deviations for the considered parameters were all lower than 1%.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75458040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joseph Elio, P. Phelan, René Villalobos, R. Milcarek
Due to high energy usage and power demand in industrial facilities, demand-side management (DSM) can simultaneously yield substantial energy cost savings for the facility and reduce the load on the power grid. There are many means of DSM, the most common being peak clipping, which is easily done with renewable energy systems and other power-generating devices. In this work, renewable energy systems (RESs) are critically reviewed and compared based on their application to industrial demand-side management (IDSM). Specifically, the RESs reviewed herein include photovoltaics, wind turbines, geothermal, and hybrid renewable energy systems. These devices are introduced, followed by a discussion of their advantages, disadvantages, and feasibility for use in IDSM. Most importantly, the reduction in the carbon footprint of power generation plants resulting from the use of RESs for IDSM is investigated. Comparisons are made based upon rated power, capital costs, O&M costs, levelized cost of energy, and the feasibility for use in industrial facilities. Using the values in the cost comparisons, the levelized cost of energy (LCOE) is derived for each device and used in a techno-economic analysis comparing the cost savings for the different RESs for a hypothetical plant.
{"title":"Renewable Energy Systems for Demand-Side Management in Industrial Facilities","authors":"Joseph Elio, P. Phelan, René Villalobos, R. Milcarek","doi":"10.1115/power2021-64381","DOIUrl":"https://doi.org/10.1115/power2021-64381","url":null,"abstract":"\u0000 Due to high energy usage and power demand in industrial facilities, demand-side management (DSM) can simultaneously yield substantial energy cost savings for the facility and reduce the load on the power grid. There are many means of DSM, the most common being peak clipping, which is easily done with renewable energy systems and other power-generating devices. In this work, renewable energy systems (RESs) are critically reviewed and compared based on their application to industrial demand-side management (IDSM). Specifically, the RESs reviewed herein include photovoltaics, wind turbines, geothermal, and hybrid renewable energy systems. These devices are introduced, followed by a discussion of their advantages, disadvantages, and feasibility for use in IDSM. Most importantly, the reduction in the carbon footprint of power generation plants resulting from the use of RESs for IDSM is investigated. Comparisons are made based upon rated power, capital costs, O&M costs, levelized cost of energy, and the feasibility for use in industrial facilities. Using the values in the cost comparisons, the levelized cost of energy (LCOE) is derived for each device and used in a techno-economic analysis comparing the cost savings for the different RESs for a hypothetical plant.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91226364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ashit Gupta, Vishal Jadhav, Mukul Patil, A. Deodhar, V. Runkana
Thermal power plants employ regenerative type air pre-heaters (APH) for recovering heat from the boiler flue gases. APH fouling occurs due to deposition of ash particles and products formed by reactions between leaked ammonia from the upstream selective catalytic reduction (SCR) unit and sulphur oxides (SOx) present in the flue gases. Fouling is strongly influenced by concentrations of ammonia and sulphur oxide as well as the flue gas temperature within APH. It increases the differential pressure across APH over time, ultimately leading to forced outages. Owing to lack of sensors within APH and the complex thermo-chemical phenomena, fouling is quite unpredictable. We present a deep learning based model for forecasting the gas differential pressure across the APH using the Long Short Term Memory (LSTM) networks. The model is trained and tested with data generated by a plant model, validated against an industrial scale APH. The model forecasts the gas differential pressure across APH within an accuracy band of 5–10% up to 3 months in advance, as a function of operating conditions. We also propose a digital twin of APH that can provide real-time insights into progression of fouling and preempt the forced outages.
{"title":"Forecasting of Fouling in Air Pre-Heaters Through Deep Learning","authors":"Ashit Gupta, Vishal Jadhav, Mukul Patil, A. Deodhar, V. Runkana","doi":"10.1115/power2021-64665","DOIUrl":"https://doi.org/10.1115/power2021-64665","url":null,"abstract":"\u0000 Thermal power plants employ regenerative type air pre-heaters (APH) for recovering heat from the boiler flue gases. APH fouling occurs due to deposition of ash particles and products formed by reactions between leaked ammonia from the upstream selective catalytic reduction (SCR) unit and sulphur oxides (SOx) present in the flue gases. Fouling is strongly influenced by concentrations of ammonia and sulphur oxide as well as the flue gas temperature within APH. It increases the differential pressure across APH over time, ultimately leading to forced outages. Owing to lack of sensors within APH and the complex thermo-chemical phenomena, fouling is quite unpredictable.\u0000 We present a deep learning based model for forecasting the gas differential pressure across the APH using the Long Short Term Memory (LSTM) networks. The model is trained and tested with data generated by a plant model, validated against an industrial scale APH. The model forecasts the gas differential pressure across APH within an accuracy band of 5–10% up to 3 months in advance, as a function of operating conditions. We also propose a digital twin of APH that can provide real-time insights into progression of fouling and preempt the forced outages.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89978442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Wittenburg, Moritz Hübel, Dorian Holtz, K. Müller
The increasing share of fluctuating electricity feed-in from wind energy and photovoltaic systems has a significant impact on the operating regime of conventional power plants. Since frequent load changes were not the focus of optimization in the past, there is still potential for improving the transient operating behavior. Exergy analyses are increasingly used to determine optimization potentials in energy conversion processes, but are mostly limited to stationary conditions. In order to perform an exergy analysis of the transient operation of a combined cycle power plant on component level, detailed information on the state and process variables of the individual components is required. These are not completely accessible via measurement data alone. For this reason, a comprehensive dynamic simulation model was developed, which includes the process components and the power plant control system. With the help of the implemented exergetic balance and state equations, the desired exergy quantities can be determined. The simulation results are used to evaluate the transient operating behaviour at different load change gradients and control actions on the basis of exergetic parameters. The exergy analysis results in an improved understanding of the causes of exergy destruction in the system, which can be used for optimization approaches. As expected, the main causes of exergy destruction are combustion processes and increased temperature gradients during transient operation. Overall, however, only moderately increased exergy destruction can be determined for the transient operation of the investigated plant compared to the steady state.
{"title":"Transient Exergy Analysis of the Dynamic Operation of a Combined Cycle Power Plant","authors":"R. Wittenburg, Moritz Hübel, Dorian Holtz, K. Müller","doi":"10.1115/power2021-64311","DOIUrl":"https://doi.org/10.1115/power2021-64311","url":null,"abstract":"\u0000 The increasing share of fluctuating electricity feed-in from wind energy and photovoltaic systems has a significant impact on the operating regime of conventional power plants. Since frequent load changes were not the focus of optimization in the past, there is still potential for improving the transient operating behavior. Exergy analyses are increasingly used to determine optimization potentials in energy conversion processes, but are mostly limited to stationary conditions.\u0000 In order to perform an exergy analysis of the transient operation of a combined cycle power plant on component level, detailed information on the state and process variables of the individual components is required. These are not completely accessible via measurement data alone. For this reason, a comprehensive dynamic simulation model was developed, which includes the process components and the power plant control system. With the help of the implemented exergetic balance and state equations, the desired exergy quantities can be determined.\u0000 The simulation results are used to evaluate the transient operating behaviour at different load change gradients and control actions on the basis of exergetic parameters. The exergy analysis results in an improved understanding of the causes of exergy destruction in the system, which can be used for optimization approaches. As expected, the main causes of exergy destruction are combustion processes and increased temperature gradients during transient operation. Overall, however, only moderately increased exergy destruction can be determined for the transient operation of the investigated plant compared to the steady state.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78432032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thermally driven vapor absorption-based air-conditioning systems possess many advantages over the compression based systems. However, intermittent availability of input resources affects the operation of these absorption systems which causes discontinuous working. This study aims at examining the electrical and thermodynamic performance of a triple-hybrid vapor absorption-assisted air-conditioning system against a conventional system with the aid of EnergyPlus simulations for a small office building. The outside weather is subjected to hot-dry climatic condition. The heat input source includes biomass and solar energy-based resources. Auxiliary heat input is also used to ensure smooth operation. The performance of the absorption system is assessed at different generator temperature (70 °C–80 °C) and solar collector area (400 m2–500 m2). The results show that, by using absorption-based systems, a maximum of 34.1% electrical energy savings can be ensured at 500 m2 collector area with 70 °C generator temperature. The coefficient of performance of the absorption system escalates from 0.50 to 0.52 by increasing the generator temperature form 70 °C to 80 °C. Under the condition of 70 °C generator temperature and 500 m2 collector area, the absorption system can be made fully renewable energy dependent.
{"title":"Energy Saving Assessment of Triple-Hybrid Vapor Absorption Building Cooling System Under Hot-Dry Climate","authors":"G. Singh, R. Das","doi":"10.1115/power2021-64470","DOIUrl":"https://doi.org/10.1115/power2021-64470","url":null,"abstract":"\u0000 Thermally driven vapor absorption-based air-conditioning systems possess many advantages over the compression based systems. However, intermittent availability of input resources affects the operation of these absorption systems which causes discontinuous working. This study aims at examining the electrical and thermodynamic performance of a triple-hybrid vapor absorption-assisted air-conditioning system against a conventional system with the aid of EnergyPlus simulations for a small office building. The outside weather is subjected to hot-dry climatic condition. The heat input source includes biomass and solar energy-based resources. Auxiliary heat input is also used to ensure smooth operation. The performance of the absorption system is assessed at different generator temperature (70 °C–80 °C) and solar collector area (400 m2–500 m2). The results show that, by using absorption-based systems, a maximum of 34.1% electrical energy savings can be ensured at 500 m2 collector area with 70 °C generator temperature. The coefficient of performance of the absorption system escalates from 0.50 to 0.52 by increasing the generator temperature form 70 °C to 80 °C. Under the condition of 70 °C generator temperature and 500 m2 collector area, the absorption system can be made fully renewable energy dependent.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79009125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Coal is one of the major sources of energy currently as it provides up to 38.5% of the total electricity produced in the world. Burning coal produces pollutants and large amounts of CO2, which contribute to climate change, environmental pollution, and health hazards. Therefore, it is our obligation to utilize coal in a cleaner way. Cleaner coal energy can be produced by using an ultra-supercritical Pulverized Coal (PC) power plant, or by employing the Integrated Gasification Combined Cycle (IGCC). Since the 1970s, the IGCC technology has been developed and demonstrated, but it has still not been widely commercialized. One of the methods to improve IGCC performance is to save the compression power of the air separation unit (ASU) by extracting the compressed air from the exit of the gas turbine as a portion of or the entire air input to the ASU. This paper investigates the effect of various levels of air integration on the IGCC performance. The results show that a moderate air integration ranging from 15% to 20% provides the most effective air-integration. An analysis of implementing a sour-shift pre-combustion carbon capture results in a significant loss of about 5.5 points in efficiency. This study also provides the effect of air integration and carbon capture on emissions including NOx, SOx, CO2, and water consumption.
{"title":"Investigation of Air Extraction and Carbon Capture in an Integrated Gasification Combined Cycle (IGCC) System","authors":"Shisir Acharya, Ting Wang","doi":"10.1115/power2021-65537","DOIUrl":"https://doi.org/10.1115/power2021-65537","url":null,"abstract":"\u0000 Coal is one of the major sources of energy currently as it provides up to 38.5% of the total electricity produced in the world. Burning coal produces pollutants and large amounts of CO2, which contribute to climate change, environmental pollution, and health hazards. Therefore, it is our obligation to utilize coal in a cleaner way. Cleaner coal energy can be produced by using an ultra-supercritical Pulverized Coal (PC) power plant, or by employing the Integrated Gasification Combined Cycle (IGCC). Since the 1970s, the IGCC technology has been developed and demonstrated, but it has still not been widely commercialized. One of the methods to improve IGCC performance is to save the compression power of the air separation unit (ASU) by extracting the compressed air from the exit of the gas turbine as a portion of or the entire air input to the ASU. This paper investigates the effect of various levels of air integration on the IGCC performance. The results show that a moderate air integration ranging from 15% to 20% provides the most effective air-integration. An analysis of implementing a sour-shift pre-combustion carbon capture results in a significant loss of about 5.5 points in efficiency. This study also provides the effect of air integration and carbon capture on emissions including NOx, SOx, CO2, and water consumption.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81150715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Cesmeci, Rubayet Hassan, M. Hassan, Ikenna Ejiogu, Matthew DeMond, Hanping Xu, Jing Tang
Supercritical CO2 (sCO2) power cycles are promising next generation power technologies, holding a great potential in fossil fuel power plants, nuclear power production, solar power, geothermal power, and ship propulsion. To unlock the potential of sCO2 power cycles, technology readiness must be demonstrated on the scale of 10–600 MWe and at sCO2 temperatures and pressures of 350–700 °C and 20–30 MPa for nuclear industries. Amongst many challenges at the component level, the lack of suitable shaft seals for sCO2 operating conditions needs to be addressed for the next generation nuclear turbine and compressor development. In this study, we propose a novel Elasto-Hydrodynamic (EHD) high-pressure, high temperature, and scalable shaft seal for sCO2 turbomachinery that offers low leakage, minimal wear, low cost, and no stress concentration. The focus in this paper was to conduct a proof-of-concept study with the help of physics-based computer simulations. The results showed that the proof-of-concept study was successfully demonstrated, warranting further investigation. Particularly, it was interesting to note the quadratic form of the leakage rate, making its peak of m ˙ = 0.075 kg/s at Pin = 15 MPa and then decaying to less than m ˙ = 0.040 kg/s at Pin = 30 MPa, suggesting that the proposed seal design could be tailored further to become a potential candidate for the shaft seal problems in sCO2 turbomachinery.
{"title":"An Innovative Elasto-Hydrodynamic Seal Concept for Supercritical CO2 Power Cycles","authors":"S. Cesmeci, Rubayet Hassan, M. Hassan, Ikenna Ejiogu, Matthew DeMond, Hanping Xu, Jing Tang","doi":"10.1115/power2021-64536","DOIUrl":"https://doi.org/10.1115/power2021-64536","url":null,"abstract":"\u0000 Supercritical CO2 (sCO2) power cycles are promising next generation power technologies, holding a great potential in fossil fuel power plants, nuclear power production, solar power, geothermal power, and ship propulsion. To unlock the potential of sCO2 power cycles, technology readiness must be demonstrated on the scale of 10–600 MWe and at sCO2 temperatures and pressures of 350–700 °C and 20–30 MPa for nuclear industries. Amongst many challenges at the component level, the lack of suitable shaft seals for sCO2 operating conditions needs to be addressed for the next generation nuclear turbine and compressor development. In this study, we propose a novel Elasto-Hydrodynamic (EHD) high-pressure, high temperature, and scalable shaft seal for sCO2 turbomachinery that offers low leakage, minimal wear, low cost, and no stress concentration. The focus in this paper was to conduct a proof-of-concept study with the help of physics-based computer simulations. The results showed that the proof-of-concept study was successfully demonstrated, warranting further investigation. Particularly, it was interesting to note the quadratic form of the leakage rate, making its peak of m ˙ = 0.075 kg/s at Pin = 15 MPa and then decaying to less than m ˙ = 0.040 kg/s at Pin = 30 MPa, suggesting that the proposed seal design could be tailored further to become a potential candidate for the shaft seal problems in sCO2 turbomachinery.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89868696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maxime Libsig, Elena Raycheva, Jared B. Garrison, G. Hug
Most studies involving the use of hydropower in an electric power system tend to consider the point of view of the system operator even though under liberalized markets in Europe, the operation of hydro units is set by the owner to maximize their profits. Such studies also often neglect uncertainties related to hydropower operation and instead assume perfect knowledge of the system conditions over the simulation horizon. This paper presents a methodology to overcome the aforementioned limitations. We optimize the operational choices of a hydropower cascade owner with multiple linked hydro assets and the ability to participate in several energy and reserve markets while also accounting for the impact of market price uncertainties on the owner’s operating decisions. The versatile optimization model created includes a detailed representation of any selected hydro cascade’s topology, constraints to reflect the machinery characteristics, and a rolling horizon approach to account for the price uncertainties in the daily operating schedule. The model is first validated using historical data for a hydro cascade in Switzerland and a perfect-knowledge approach. Next, price uncertainty is added to improve the historical simulation results and find a trade-off between accuracy and computational time.
{"title":"Modeling and Validation of Hydro Cascade Operation Considering Price Uncertainty","authors":"Maxime Libsig, Elena Raycheva, Jared B. Garrison, G. Hug","doi":"10.1115/power2021-65726","DOIUrl":"https://doi.org/10.1115/power2021-65726","url":null,"abstract":"\u0000 Most studies involving the use of hydropower in an electric power system tend to consider the point of view of the system operator even though under liberalized markets in Europe, the operation of hydro units is set by the owner to maximize their profits. Such studies also often neglect uncertainties related to hydropower operation and instead assume perfect knowledge of the system conditions over the simulation horizon. This paper presents a methodology to overcome the aforementioned limitations. We optimize the operational choices of a hydropower cascade owner with multiple linked hydro assets and the ability to participate in several energy and reserve markets while also accounting for the impact of market price uncertainties on the owner’s operating decisions. The versatile optimization model created includes a detailed representation of any selected hydro cascade’s topology, constraints to reflect the machinery characteristics, and a rolling horizon approach to account for the price uncertainties in the daily operating schedule. The model is first validated using historical data for a hydro cascade in Switzerland and a perfect-knowledge approach. Next, price uncertainty is added to improve the historical simulation results and find a trade-off between accuracy and computational time.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87002779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gasoline direct injection (GDI) is a promising solution to increase engine thermal efficiency and reduce exhaust gas emissions. The GDI operation requires an understanding of fuel penetration and droplet size, which can be investigated numerically. In the numerical simulation, primary and secondary breakup phenomena are studied by the Kelvin-Helmholtz/Rayleigh-Taylor (KH-RT) wave breakup models. The models were initially developed for diesel fuel injection, and in the present work, the models are extended to the GDI application combined using large-eddy simulation (LES). The simulation is conducted using the KIVA4 code. Measured data of experimental spray penetration and Mie-scattering image comparisons are carried out under non-reactive conditions at an ambient temperature of 613K and a density of 4.84 kg/m3. The spray penetration and structures using LES are compared with traditional Reynolds-Averaged Navier-Stokes (RANS). Grid size effects in the simulation using LES and RANS models are also investigated to find a reasonable cell size for future reactive gasoline spray/combustion studies. The fuel spray penetration and droplet size are dependent on specific parameters. Parametric studies on the effects of adjustable constants of the KH-RT models, such as time constants, size constants, and breakup length constant, are discussed. Liquid penetrations from the RANS turbulence model are similar to that of the LES turbulence model’s prediction. However, the RANS model is not able to capture the spray structure well.
汽油直喷(GDI)是一个很有前途的解决方案，以提高发动机的热效率和减少废气排放。GDI操作需要了解燃料渗透和液滴大小，这可以进行数值研究。在数值模拟中，采用Kelvin-Helmholtz/Rayleigh-Taylor (KH-RT)波破裂模型研究了初级和次级破裂现象。该模型最初是针对柴油喷射建立的，在本工作中，将该模型与大涡模拟(LES)相结合，扩展到直喷发动机的应用。使用KIVA4代码进行仿真。在无反应条件下，在环境温度为613K，密度为4.84 kg/m3的条件下，进行了实验喷雾穿透测量数据和mie散射图像对比。并与传统的RANS (reynolds - average Navier-Stokes)方法进行了比较。在使用LES和RANS模型的模拟中，还研究了网格尺寸的影响，以便为未来的反应性汽油喷雾/燃烧研究找到合理的电池尺寸。燃油喷射穿透度和液滴大小取决于特定的参数。讨论了时间常数、尺寸常数和破裂长度常数等可调常数对KH-RT模型的影响。RANS湍流模型预测的液体穿透量与LES湍流模型预测的相似。然而，RANS模型不能很好地捕捉喷雾结构。
{"title":"Numerical Study on the Adaptation of Diesel Wave Breakup Model for Large-Eddy Simulation of Non-Reactive Gasoline Spray","authors":"R. Sok, Beini Zhou, Jin Kusaka","doi":"10.1115/power2021-64537","DOIUrl":"https://doi.org/10.1115/power2021-64537","url":null,"abstract":"\u0000 Gasoline direct injection (GDI) is a promising solution to increase engine thermal efficiency and reduce exhaust gas emissions. The GDI operation requires an understanding of fuel penetration and droplet size, which can be investigated numerically. In the numerical simulation, primary and secondary breakup phenomena are studied by the Kelvin-Helmholtz/Rayleigh-Taylor (KH-RT) wave breakup models. The models were initially developed for diesel fuel injection, and in the present work, the models are extended to the GDI application combined using large-eddy simulation (LES). The simulation is conducted using the KIVA4 code.\u0000 Measured data of experimental spray penetration and Mie-scattering image comparisons are carried out under non-reactive conditions at an ambient temperature of 613K and a density of 4.84 kg/m3. The spray penetration and structures using LES are compared with traditional Reynolds-Averaged Navier-Stokes (RANS). Grid size effects in the simulation using LES and RANS models are also investigated to find a reasonable cell size for future reactive gasoline spray/combustion studies. The fuel spray penetration and droplet size are dependent on specific parameters. Parametric studies on the effects of adjustable constants of the KH-RT models, such as time constants, size constants, and breakup length constant, are discussed. Liquid penetrations from the RANS turbulence model are similar to that of the LES turbulence model’s prediction. However, the RANS model is not able to capture the spray structure well.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76610352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：