Permanent magnet direct drive (PMDD) electric machines are advantageous due to higher efficiencies and lower maintenance concerns. For wind turbine generators, especially offshore turbines, this is advantageous to geared machines and is currently implemented by manufacturers such as GE, Siemens and Enercon. By nature, a direct drive machine must be larger than its geared counterpart in order to output the same power. As a result, the structural mass is larger and makes the machine prohibitively large. However, the structural mass and electromagnetic design is coupled and the electromagnetic criteria are an important consideration in the structural design. In this analysis, the electromagnetic design of a 5 MW PMDD generator was coupled to a triply periodic minimal surface (TPMS) lattice generator through means of an evolutionary algorithm. Finite element analysis (FEA) was used to determine the radial, torsional, and axial deformations under simulated wind turbine generator loading conditions subject to critical deflection criteria. Lattice functional grading was completed with the FEA deflection data in order to further optimize the structural mass. For the 5 MW test case, functional graded TPMS support structures maintained stiffness for a generator with a 32% higher force density with inactive mass 4% lower than baseline. This study suggests functional grading of TPMS lattice structures for wind turbine generators has the potential at significant mass savings.
{"title":"Coupled Electromagnetic and Lattice Structure Optimization for the Rotor and Stator of Large Electric Machines","authors":"Austin C. Hayes, G. Whiting","doi":"10.1115/power2021-62625","DOIUrl":"https://doi.org/10.1115/power2021-62625","url":null,"abstract":"\u0000 Permanent magnet direct drive (PMDD) electric machines are advantageous due to higher efficiencies and lower maintenance concerns. For wind turbine generators, especially offshore turbines, this is advantageous to geared machines and is currently implemented by manufacturers such as GE, Siemens and Enercon. By nature, a direct drive machine must be larger than its geared counterpart in order to output the same power. As a result, the structural mass is larger and makes the machine prohibitively large. However, the structural mass and electromagnetic design is coupled and the electromagnetic criteria are an important consideration in the structural design. In this analysis, the electromagnetic design of a 5 MW PMDD generator was coupled to a triply periodic minimal surface (TPMS) lattice generator through means of an evolutionary algorithm. Finite element analysis (FEA) was used to determine the radial, torsional, and axial deformations under simulated wind turbine generator loading conditions subject to critical deflection criteria. Lattice functional grading was completed with the FEA deflection data in order to further optimize the structural mass. For the 5 MW test case, functional graded TPMS support structures maintained stiffness for a generator with a 32% higher force density with inactive mass 4% lower than baseline. This study suggests functional grading of TPMS lattice structures for wind turbine generators has the potential at significant mass savings.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90460231","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}
An electrical generator is one of the most efficient large-scale machines. It converts mechanical to electrical energy with an efficiency coefficient of approximately 99%. The remaining 1% can mainly be contributed to heat losses. Direct cooling is only necessary for larger turbogenerators with more than 250 MVA where the cooling media is introduced via hollow conductors within the stator bars. Turbogenerators of approximately up to 700 MVA nowadays use exclusively hydrogen (H2) gas as a cooling media. Even larger turbogenerators have to introduce direct water cooling. The water chemistry of the stator cooling water is typically of neutral pH and has a conductivity of less than 0.1 μS/cm. Two zones of the oxygen (O2) concentration have been established through the last 50 years, one at low dissolved O2 concentration with less than 20 ppb, the other with high concentrations of more than 2 ppm. The latter has to continuously inject CO2 free air to ensure to always keep the oxygen concentration above 2 ppm. The first part of this publication shows several incidents with the air injection system in different Nuclear Power Plants in the US, resulting in unfavorable stator cooling water chemistry. This led to a reduced cooling efficiency, resulting in several chemical online cleanings being necessary. The second part of this work presents a technical solution to overcome the issues associated with the reduced stator cooling. It continuously injects and monitors the air injected into the system. Additionally, it also measures the hydrogen leakage rate.
{"title":"Stator Leakage Monitoring System in Water-Cooled Generators: Problems and Solutions","authors":"T. Bauer, M. Svoboda","doi":"10.1115/power2021-65471","DOIUrl":"https://doi.org/10.1115/power2021-65471","url":null,"abstract":"\u0000 An electrical generator is one of the most efficient large-scale machines. It converts mechanical to electrical energy with an efficiency coefficient of approximately 99%. The remaining 1% can mainly be contributed to heat losses. Direct cooling is only necessary for larger turbogenerators with more than 250 MVA where the cooling media is introduced via hollow conductors within the stator bars. Turbogenerators of approximately up to 700 MVA nowadays use exclusively hydrogen (H2) gas as a cooling media. Even larger turbogenerators have to introduce direct water cooling.\u0000 The water chemistry of the stator cooling water is typically of neutral pH and has a conductivity of less than 0.1 μS/cm. Two zones of the oxygen (O2) concentration have been established through the last 50 years, one at low dissolved O2 concentration with less than 20 ppb, the other with high concentrations of more than 2 ppm. The latter has to continuously inject CO2 free air to ensure to always keep the oxygen concentration above 2 ppm.\u0000 The first part of this publication shows several incidents with the air injection system in different Nuclear Power Plants in the US, resulting in unfavorable stator cooling water chemistry. This led to a reduced cooling efficiency, resulting in several chemical online cleanings being necessary.\u0000 The second part of this work presents a technical solution to overcome the issues associated with the reduced stator cooling. It continuously injects and monitors the air injected into the system. Additionally, it also measures the hydrogen leakage rate.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79281323","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}
This paper uses an experimental approach to evaluate two design characteristics for a liquid air energy storage (LAES) and generation system as part of the design analysis for a microgrid power system. The system evaluated utilized a Stirling engine based cryocooler that employs a coldfinger placed into a Dewar. Using a design of experiments, the cold finger surface area and Dewar volume were evaluated to determine the criticality and significance of changing their dimensions. Evaluations were made against the total liquid air production mass and average liquid air production rate during the experiments. This analysis found that changing the surface area of the cryocooler cold finger was a statistically significant design characteristic that affected total liquid air production and average production rate while changing the volume of the Dewar was not statistically significant. Additional responses relative to the time when the first gram of liquid air was produced and the minimum cold tip temperature that the cryocooler was able to achieve provided additional insight into design characteristics that can be used to inform the engineer when making design tradeoffs for specific operational environments.
{"title":"Experimental Evaluation of Dewar Volume and Cryocooler Cold Finger Size in a Small-Scale Stirling Liquid Air Energy Storage (LAES) System","authors":"Howard M. Swanson, A. Pollman, A. Hernández","doi":"10.1115/power2021-60565","DOIUrl":"https://doi.org/10.1115/power2021-60565","url":null,"abstract":"\u0000 This paper uses an experimental approach to evaluate two design characteristics for a liquid air energy storage (LAES) and generation system as part of the design analysis for a microgrid power system. The system evaluated utilized a Stirling engine based cryocooler that employs a coldfinger placed into a Dewar. Using a design of experiments, the cold finger surface area and Dewar volume were evaluated to determine the criticality and significance of changing their dimensions. Evaluations were made against the total liquid air production mass and average liquid air production rate during the experiments. This analysis found that changing the surface area of the cryocooler cold finger was a statistically significant design characteristic that affected total liquid air production and average production rate while changing the volume of the Dewar was not statistically significant. Additional responses relative to the time when the first gram of liquid air was produced and the minimum cold tip temperature that the cryocooler was able to achieve provided additional insight into design characteristics that can be used to inform the engineer when making design tradeoffs for specific operational environments.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73005370","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}
Gretchell M. Hiraldo-Martínez, Alex D. Santiago-Vargas, Diego A. Aponte-Roa, Miguel A. Goenaga-Jimenez
The inclusion of renewable energy as wind turbines on microgrids has been increasing in popularity. However, commercial micro wind turbines lack advance electronic control systems to monitor the turbine and automatically brake for safety purposes. This paper presents the design of a modular electronic braking and monitoring system architecture with off-the-shelf electronic components and open-source software. The proposed system records the turbine operational parameters and triggers a braking system when an emergency stop button is closed or when a desired electrical parameter exceeds an established threshold. Electronic braking is a low-cost alternative that needs less maintenance, space, and mechanical complexity. We used a 400W micro wind turbine located at 17 feet high to test the proposed system architecture. Results demonstrate that this system architecture could be implemented for wind turbines in any existing polygeneration microgrid as an add-on.
{"title":"Automatic Electronic Braking System for Commercial Micro Wind Turbine","authors":"Gretchell M. Hiraldo-Martínez, Alex D. Santiago-Vargas, Diego A. Aponte-Roa, Miguel A. Goenaga-Jimenez","doi":"10.1115/power2021-65883","DOIUrl":"https://doi.org/10.1115/power2021-65883","url":null,"abstract":"\u0000 The inclusion of renewable energy as wind turbines on microgrids has been increasing in popularity. However, commercial micro wind turbines lack advance electronic control systems to monitor the turbine and automatically brake for safety purposes. This paper presents the design of a modular electronic braking and monitoring system architecture with off-the-shelf electronic components and open-source software. The proposed system records the turbine operational parameters and triggers a braking system when an emergency stop button is closed or when a desired electrical parameter exceeds an established threshold. Electronic braking is a low-cost alternative that needs less maintenance, space, and mechanical complexity. We used a 400W micro wind turbine located at 17 feet high to test the proposed system architecture. Results demonstrate that this system architecture could be implemented for wind turbines in any existing polygeneration microgrid as an add-on.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83603251","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}
A low-carbon world needs a replacement for natural gas-fired power to provide variable heat and electricity. The coupling of simple or combined cycle gas turbines (CCGTs) with advanced electrically-heated thermal energy storage (E-TES) systems is an alternative approach to energy storage with cost advantages over batteries or hydrogen production. CCGTs with E-TES may use stored low-value electricity to run the power cycle in place of fossil fuels. This (1) saves money for the power plants by allowing them to switch heat sources based on price, and (2) reduces carbon emissions by making use of otherwise curtailed renewable energy. The development of electrically conductive firebricks enables temperatures approaching 2000°C, hotter than existing E-TES options, sufficient to run CCGTs. Levelized cost of storage (LCOS) calculations show that the use of CCGTs with novel E-TES increases the cost of energy by less than a factor of 2, compared to a factor of 9 increase when using lithium-ion batteries. Unlike batteries, the CCGT with E-TES, provides assured generating capacity by normal operation of the gas turbine. A case study of CCGT coupled with E-TES is included based on 2019 electricity prices in Southern California, which showed an 18% reduction in fuel consumption and $11M savings based purely on the arbitrage case. The arbitrage case is expected to improve dramatically over the decade as deployment of renewable energy in California increases.
{"title":"Combined Cycle Gas Turbines With Electrically-Heated Thermal Energy Storage for Dispatchable Zero-Carbon Electricity","authors":"Daniel C. Stack, C. Forsberg","doi":"10.1115/power2021-65528","DOIUrl":"https://doi.org/10.1115/power2021-65528","url":null,"abstract":"\u0000 A low-carbon world needs a replacement for natural gas-fired power to provide variable heat and electricity. The coupling of simple or combined cycle gas turbines (CCGTs) with advanced electrically-heated thermal energy storage (E-TES) systems is an alternative approach to energy storage with cost advantages over batteries or hydrogen production. CCGTs with E-TES may use stored low-value electricity to run the power cycle in place of fossil fuels. This (1) saves money for the power plants by allowing them to switch heat sources based on price, and (2) reduces carbon emissions by making use of otherwise curtailed renewable energy. The development of electrically conductive firebricks enables temperatures approaching 2000°C, hotter than existing E-TES options, sufficient to run CCGTs. Levelized cost of storage (LCOS) calculations show that the use of CCGTs with novel E-TES increases the cost of energy by less than a factor of 2, compared to a factor of 9 increase when using lithium-ion batteries. Unlike batteries, the CCGT with E-TES, provides assured generating capacity by normal operation of the gas turbine. A case study of CCGT coupled with E-TES is included based on 2019 electricity prices in Southern California, which showed an 18% reduction in fuel consumption and $11M savings based purely on the arbitrage case. The arbitrage case is expected to improve dramatically over the decade as deployment of renewable energy in California increases.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77682813","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}
M. Bade, Vince Meyers, Eric L. Suits, A. Mannarino, J. Subramanian
The development of highly compact and energy-efficient systems is critical for world energy security and technology leadership. Due to the abundance of natural gas, the natural gas fueled distributed energy systems that lower the energy consumption and utility costs would be ideal in the U.S. as well as worldwide markets. To meet these objectives, researchers from Enginuity Power Systems (EPS) are currently working on the development of an ultra-efficient Combined Heat and Power (CHP) system for residential and commercial applications. These CHP systems generate electricity at the point of use while also meeting the space and water heating demands. Furthermore, a single CHP system replaces the conventional electricity generator, space, and water heating systems in residential and commercial applications. The main technical objective of this research article is the demonstration of the fundamental design and performance characteristics of an EPS’s 6 kW–10 kW CHP system intended for residential applications. The proposed residential system utilized a mirror-balanced, patented, inwardly opposed piston, four-stroke internal combustion engine as a prime mover. This novel four-stroke opposed piston design resolved the scavenging, cooling, and lubrication issues faced by the conventional opposed designs in the market while also maintaining the power density, balancing, and performance benefits. Initially, a series of experiments were conducted on the proposed system for different speeds and throttle openings. Later, the combustion, performance, and quantified energy loss pathways were presented at Wide Open Throttle (WOT) conditions to demonstrate the performance benefits of the proposed system. Finally, a performance-oriented framework was developed for the proposed CHP system for future efforts.
{"title":"Enginuity’s Combined Heat and Power (CHP) System Part 1: Fundamental Design & Performance Evaluation of Residential Engine System","authors":"M. Bade, Vince Meyers, Eric L. Suits, A. Mannarino, J. Subramanian","doi":"10.1115/power2021-64122","DOIUrl":"https://doi.org/10.1115/power2021-64122","url":null,"abstract":"\u0000 The development of highly compact and energy-efficient systems is critical for world energy security and technology leadership. Due to the abundance of natural gas, the natural gas fueled distributed energy systems that lower the energy consumption and utility costs would be ideal in the U.S. as well as worldwide markets. To meet these objectives, researchers from Enginuity Power Systems (EPS) are currently working on the development of an ultra-efficient Combined Heat and Power (CHP) system for residential and commercial applications. These CHP systems generate electricity at the point of use while also meeting the space and water heating demands. Furthermore, a single CHP system replaces the conventional electricity generator, space, and water heating systems in residential and commercial applications. The main technical objective of this research article is the demonstration of the fundamental design and performance characteristics of an EPS’s 6 kW–10 kW CHP system intended for residential applications. The proposed residential system utilized a mirror-balanced, patented, inwardly opposed piston, four-stroke internal combustion engine as a prime mover. This novel four-stroke opposed piston design resolved the scavenging, cooling, and lubrication issues faced by the conventional opposed designs in the market while also maintaining the power density, balancing, and performance benefits. Initially, a series of experiments were conducted on the proposed system for different speeds and throttle openings. Later, the combustion, performance, and quantified energy loss pathways were presented at Wide Open Throttle (WOT) conditions to demonstrate the performance benefits of the proposed system. Finally, a performance-oriented framework was developed for the proposed CHP system for future efforts.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90902609","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}
Andrew Ahn, T. Welles, B. Akih-Kumgeh, R. Milcarek
Climate change concerns have forced the automotive industry to develop more efficient powertrain technologies, including the potential for fuel cell systems. Solid oxide fuel cells (SOFCs) demonstrate exceptional fuel flexibility and can operate on conventional, widely available hydrocarbon fuels with limited requirements for fuel reformation. Current hybrid powertrains combining fuel cell systems with internal combustion engines (ICEs) fail to mitigate the disadvantages of requiring fuel reformation by placing the engine downstream of the fuel cell system. This work, thus investigates the upstream placement of the engine, eliminating the need for fuel processing catalysts and the heating of complex fuel reformers. The ICE burns a fuel-rich mixture through rapid compression ignition, performing partial oxidation fuel reformation. To test the feasibility of a fuel cell system operating on such ICE exhaust, chemical kinetic model simulations were performed, creating model exhaust containing ∼43.0% syngas. A micro-tubular SOFC (μT-SOFC) was tested for power output with this exhaust, and generated ∼730 mW/cm2 (∼86% of its maximum output obtained with pure hydrogen fuel). Combustion testing was subsequently performed in a test chamber, and despite insufficient equipment limiting the maximum pressure of the combustion chamber, began to validate the model. The exhaust from these tests contained all of the predicted chemical species and, on average, ∼21.8% syngas, but would have resembled the model more closely given higher pressures. This work examines the viability of a novel combined ICE and fuel cell hybrid system, displaying potential for a more cost-effective/efficient solution than current fuel cell systems.
{"title":"Experimental Investigation of a Novel Combined Rapid Compression-Ignition Combustion and Solid Oxide Fuel Cell System Format Operating on Diesel","authors":"Andrew Ahn, T. Welles, B. Akih-Kumgeh, R. Milcarek","doi":"10.1115/power2021-64197","DOIUrl":"https://doi.org/10.1115/power2021-64197","url":null,"abstract":"\u0000 Climate change concerns have forced the automotive industry to develop more efficient powertrain technologies, including the potential for fuel cell systems. Solid oxide fuel cells (SOFCs) demonstrate exceptional fuel flexibility and can operate on conventional, widely available hydrocarbon fuels with limited requirements for fuel reformation. Current hybrid powertrains combining fuel cell systems with internal combustion engines (ICEs) fail to mitigate the disadvantages of requiring fuel reformation by placing the engine downstream of the fuel cell system. This work, thus investigates the upstream placement of the engine, eliminating the need for fuel processing catalysts and the heating of complex fuel reformers. The ICE burns a fuel-rich mixture through rapid compression ignition, performing partial oxidation fuel reformation. To test the feasibility of a fuel cell system operating on such ICE exhaust, chemical kinetic model simulations were performed, creating model exhaust containing ∼43.0% syngas. A micro-tubular SOFC (μT-SOFC) was tested for power output with this exhaust, and generated ∼730 mW/cm2 (∼86% of its maximum output obtained with pure hydrogen fuel). Combustion testing was subsequently performed in a test chamber, and despite insufficient equipment limiting the maximum pressure of the combustion chamber, began to validate the model. The exhaust from these tests contained all of the predicted chemical species and, on average, ∼21.8% syngas, but would have resembled the model more closely given higher pressures. This work examines the viability of a novel combined ICE and fuel cell hybrid system, displaying potential for a more cost-effective/efficient solution than current fuel cell systems.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86293888","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}
A. Berastain, Rafael Vidal, Carlos Busquets, Gonzalo Aguilar, Álvaro Torres, Jorge Lem, Antonios Antoniou, Cesar Celis
The objective of this work is to discuss design considerations related to the development of a stand-alone photovoltaic driven hydrogen production and consumption system. The referred system is currently on the design-phase so this work describes in particular the associated design considerations, governing equations, schematics and the expected system efficiency. The system design requirements include the production of enough energy to power an average residence located in the Ica city, Peru. The system design has been divided in four subsystems, each one having its own design considerations and limitations, (i) power, hydrogen (ii) production, (iii) storage and (iv) consumption. Regarding the power subsystem, the required considerations to generate the maximum amount of solar energy in the minimum amount of space are presented. For hydrogen production, different electrolyzer related technologies have been accounted for; including proton exchange (PEM), alkaline (AEC) and polymer (PEC). Hydrogen and oxygen storages are a critical aspect in the full hydrogen chain production. Currently no single technology satisfies all of the criteria required. As such, present technologies and selection considerations are presented. For using the produced hydrogen, fuel cell stacks including PEM and solid oxide ones are assessed. Finally, the right the combination of current, voltage (including conversion from DC to a constant AC supply) and fuel utilization maximizing efficiency and power output is determined.
{"title":"Design Considerations of Solar-Driven Hydrogen Production Plants for Residential Applications","authors":"A. Berastain, Rafael Vidal, Carlos Busquets, Gonzalo Aguilar, Álvaro Torres, Jorge Lem, Antonios Antoniou, Cesar Celis","doi":"10.1115/power2021-65858","DOIUrl":"https://doi.org/10.1115/power2021-65858","url":null,"abstract":"\u0000 The objective of this work is to discuss design considerations related to the development of a stand-alone photovoltaic driven hydrogen production and consumption system. The referred system is currently on the design-phase so this work describes in particular the associated design considerations, governing equations, schematics and the expected system efficiency. The system design requirements include the production of enough energy to power an average residence located in the Ica city, Peru. The system design has been divided in four subsystems, each one having its own design considerations and limitations, (i) power, hydrogen (ii) production, (iii) storage and (iv) consumption. Regarding the power subsystem, the required considerations to generate the maximum amount of solar energy in the minimum amount of space are presented. For hydrogen production, different electrolyzer related technologies have been accounted for; including proton exchange (PEM), alkaline (AEC) and polymer (PEC). Hydrogen and oxygen storages are a critical aspect in the full hydrogen chain production. Currently no single technology satisfies all of the criteria required. As such, present technologies and selection considerations are presented. For using the produced hydrogen, fuel cell stacks including PEM and solid oxide ones are assessed. Finally, the right the combination of current, voltage (including conversion from DC to a constant AC supply) and fuel utilization maximizing efficiency and power output is determined.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77135493","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}
Since the solid fuels like coal produce a lot of ash upon burning, the products of combustion can’t be expanded as it is in a Gas Turbine (GT). Hence, the operation of a combined cycle with solid fuels includes: (i) production of syngas from the coal to operate a gas turbine engine and (ii) using the leftover coal after gasification to produce steam and operate a steam turbine engine. To avoid the coal-gasification and to use the solid coal fuel as it is in a combined cycle power plant, a novel Air-Steam Combined Cycle (ASCC) is proposed in the present work. ASCC comprises a gas turbine cycle (operating by the Brayton cycle) with the air as the working fluid and a steam turbine cycle (operating by the Rankine cycle) with the steam as the working fluid. A fraction F of the air is compressed, regenerated and finally heated to an Air Turbine Inlet Temperature (ATIT) by the hot products of combustion produced upon burning of the bituminous coal in a combustor. The residual heat energy of products of combustion is then utilized in a Heat Recovery Steam Generator (HRSG) to generate the steam initially and subsequently to preheat the remaining fraction (1-F) of the air. After expansion in an air turbine, the hot air passes through a regenerator directly into a combustor along with the preheated air for burning the coal so as to utilize the energy of expanded air completely. ASCC is analyzed based on the first and second laws of thermodynamics and a computer code is developed in MATLAB to simulate the cycle performance at different compressor pressure ratios, ATITs, and HRSG pressures. The performance of ASCC is compared with that of Baseline Steam Turbine Cycle (BSTC) for the same flue gas (stack) temperature. It is found that the overall thermal efficiency of ASCC can go up to 33.0%–37.5% depending on the compressor pressure ratio, ATIT and HRSG pressure as against to 29.0%–29.5% of BSTC.
{"title":"Investigation of the Performance of Air-Steam Combined Cycle for Electric Power Plants Using Low Grade Solid Fuels","authors":"Pereddy Nageswara Reddy","doi":"10.1115/power2021-64788","DOIUrl":"https://doi.org/10.1115/power2021-64788","url":null,"abstract":"\u0000 Since the solid fuels like coal produce a lot of ash upon burning, the products of combustion can’t be expanded as it is in a Gas Turbine (GT). Hence, the operation of a combined cycle with solid fuels includes: (i) production of syngas from the coal to operate a gas turbine engine and (ii) using the leftover coal after gasification to produce steam and operate a steam turbine engine. To avoid the coal-gasification and to use the solid coal fuel as it is in a combined cycle power plant, a novel Air-Steam Combined Cycle (ASCC) is proposed in the present work. ASCC comprises a gas turbine cycle (operating by the Brayton cycle) with the air as the working fluid and a steam turbine cycle (operating by the Rankine cycle) with the steam as the working fluid. A fraction F of the air is compressed, regenerated and finally heated to an Air Turbine Inlet Temperature (ATIT) by the hot products of combustion produced upon burning of the bituminous coal in a combustor. The residual heat energy of products of combustion is then utilized in a Heat Recovery Steam Generator (HRSG) to generate the steam initially and subsequently to preheat the remaining fraction (1-F) of the air. After expansion in an air turbine, the hot air passes through a regenerator directly into a combustor along with the preheated air for burning the coal so as to utilize the energy of expanded air completely. ASCC is analyzed based on the first and second laws of thermodynamics and a computer code is developed in MATLAB to simulate the cycle performance at different compressor pressure ratios, ATITs, and HRSG pressures. The performance of ASCC is compared with that of Baseline Steam Turbine Cycle (BSTC) for the same flue gas (stack) temperature. It is found that the overall thermal efficiency of ASCC can go up to 33.0%–37.5% depending on the compressor pressure ratio, ATIT and HRSG pressure as against to 29.0%–29.5% of BSTC.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77935176","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}
Xiang Zhou, Shangyan Zou, W. Weaver, O. Abdelkhalik
A permanent magnet linear electrical machine power takeoff (PTO) unit is simulated on the direct drive wave energy converter in this paper, which is controlled to provide the required reactive power. A shape-based control is implemented to maximize the wave energy production (mechanical PTO) with the limiting constraints on the electric drive. Further, the linear electrical machine design is optimized such that the electrical power output is maximized (e.g., reduced power losses). The numerical simulations are conducted using MATLAB/Simulink and the Simscape toolbox. Linear wave theory is applied in modeling the buoy dynamics. Additionally, the PTO unit is composed of a linear electrical machine, an ideal inverter, and an ideal energy storage system. The results show the proposed PTO tracks the reference control accurately. The electrical power output is significantly improved by limiting the current in the PTO compared to a passive control.
{"title":"Control of Wave Energy Converter With Losses in Electrical Power Take-Off System","authors":"Xiang Zhou, Shangyan Zou, W. Weaver, O. Abdelkhalik","doi":"10.1115/power2021-64938","DOIUrl":"https://doi.org/10.1115/power2021-64938","url":null,"abstract":"\u0000 A permanent magnet linear electrical machine power takeoff (PTO) unit is simulated on the direct drive wave energy converter in this paper, which is controlled to provide the required reactive power. A shape-based control is implemented to maximize the wave energy production (mechanical PTO) with the limiting constraints on the electric drive. Further, the linear electrical machine design is optimized such that the electrical power output is maximized (e.g., reduced power losses). The numerical simulations are conducted using MATLAB/Simulink and the Simscape toolbox. Linear wave theory is applied in modeling the buoy dynamics. Additionally, the PTO unit is composed of a linear electrical machine, an ideal inverter, and an ideal energy storage system. The results show the proposed PTO tracks the reference control accurately. The electrical power output is significantly improved by limiting the current in the PTO compared to a passive control.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89547146","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}
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