Jeongmin Seo, W. Choi, Hyung-Soo Lim, Mooryong Park, Dongho Kim, K. Lee, E. Yoon
Korea Institute of Machinery & Materials (KIMM) investigated a supercritical carbon dioxide (sCO2) cycle for a heat recovery power generation system for several years. The objective of the study focuses on the development of the technologies and the establishment of the development procedure of turbomachinery, heat exchangers, and auxiliary equipment for the sCO2 power cycle. A motor-driven centrifugal starter pump with an inducer is developed for startup operation. The main pump-drive turbine module adopts magnetic bearings as axial and radial bearings to remove oil lubrication and exhibits a hermetic structure to eliminate leakage problems. The power turbine and a generator are linked via a gearbox in the power turbine-generator module. An oil bearing and floating ring seal with dry gas injection are applied to minimize sCO2 leakage. The recuperator is developed as a printed circuit heat exchanger (PCHE) owing to its high efficiency and compactness. The integrated test facility is designed as a 250-kWe class sCO2 recuperated Rankine cycle to evaluate the performance of the core modules as opposed to demonstrating the viability of a particular sCO2 cycle. The test facility is proven to successfully operate in startup mode and self-sustaining mode using the starter pump and the main pump-drive turbine module. An overview of the operation of the startup mode and self-sustaining mode is presented.
{"title":"Development of a 250-kWe Class Supercritical Carbon Dioxide Rankine Cycle Power Generation System and its Core Components","authors":"Jeongmin Seo, W. Choi, Hyung-Soo Lim, Mooryong Park, Dongho Kim, K. Lee, E. Yoon","doi":"10.1115/gt2019-90337","DOIUrl":"https://doi.org/10.1115/gt2019-90337","url":null,"abstract":"\u0000 Korea Institute of Machinery & Materials (KIMM) investigated a supercritical carbon dioxide (sCO2) cycle for a heat recovery power generation system for several years. The objective of the study focuses on the development of the technologies and the establishment of the development procedure of turbomachinery, heat exchangers, and auxiliary equipment for the sCO2 power cycle. A motor-driven centrifugal starter pump with an inducer is developed for startup operation. The main pump-drive turbine module adopts magnetic bearings as axial and radial bearings to remove oil lubrication and exhibits a hermetic structure to eliminate leakage problems. The power turbine and a generator are linked via a gearbox in the power turbine-generator module. An oil bearing and floating ring seal with dry gas injection are applied to minimize sCO2 leakage. The recuperator is developed as a printed circuit heat exchanger (PCHE) owing to its high efficiency and compactness.\u0000 The integrated test facility is designed as a 250-kWe class sCO2 recuperated Rankine cycle to evaluate the performance of the core modules as opposed to demonstrating the viability of a particular sCO2 cycle. The test facility is proven to successfully operate in startup mode and self-sustaining mode using the starter pump and the main pump-drive turbine module. An overview of the operation of the startup mode and self-sustaining mode is presented.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124222337","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}
C. Lim, G. Pathikonda, Sandeep R. Pidaparti, Devesh Ranjan
Supercritical carbon dioxide (sCO2) power cycles have the potential to offer a higher plant efficiency than the traditional Rankine superheated/supercritical steam cycle or Helium Brayton cycles. The most attractive characteristic of sCO2 is that the fluid density is high near the critical point, allowing compressors to consume less power than conventional gas Brayton cycles and maintain a smaller turbomachinery size. Despite these advantages, there still exist unsolved challenges in design and operation of sCO2 compressors near the critical point. Drastic changes in fluid properties near the critical point and the high compressibility of the fluid pose several challenges. Operating a sCO2 compressor near the critical point has potential to produce two phase flow, which can be detrimental to turbomachinery performance. To mimic the expanding regions of compressor blades, flow through a converging-diverging nozzle is investigated. Pressure profiles along the nozzle are recorded and presented for operating conditions near the critical point. Using high speed shadowgraph images, onset and growth of condensation is captured along the nozzle. Pressure profiles were calculated using a one-dimensional homogeneous equilibrium model and compared with experimental data.
{"title":"Visualization of Supercritical Carbon Dioxide Flow Through a Converging-Diverging Nozzle","authors":"C. Lim, G. Pathikonda, Sandeep R. Pidaparti, Devesh Ranjan","doi":"10.1115/gt2019-91691","DOIUrl":"https://doi.org/10.1115/gt2019-91691","url":null,"abstract":"\u0000 Supercritical carbon dioxide (sCO2) power cycles have the potential to offer a higher plant efficiency than the traditional Rankine superheated/supercritical steam cycle or Helium Brayton cycles. The most attractive characteristic of sCO2 is that the fluid density is high near the critical point, allowing compressors to consume less power than conventional gas Brayton cycles and maintain a smaller turbomachinery size. Despite these advantages, there still exist unsolved challenges in design and operation of sCO2 compressors near the critical point. Drastic changes in fluid properties near the critical point and the high compressibility of the fluid pose several challenges. Operating a sCO2 compressor near the critical point has potential to produce two phase flow, which can be detrimental to turbomachinery performance. To mimic the expanding regions of compressor blades, flow through a converging-diverging nozzle is investigated. Pressure profiles along the nozzle are recorded and presented for operating conditions near the critical point. Using high speed shadowgraph images, onset and growth of condensation is captured along the nozzle. Pressure profiles were calculated using a one-dimensional homogeneous equilibrium model and compared with experimental data.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114264340","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}
Compact heat exchangers for supercritical CO2 (sCO2) service are often designed with external, semi-circular headers. Their design is governed by the ASME Boiler & Pressure Vessel Code (BPVC) whose equations were typically derived by following Castigliano’s Theorems. However, there are no known validation experiments to support their claims of pressure rating or burst pressure predictions nor is there much information about how and where failures occur. This work includes high pressure bursting of three semi-circular header prototypes for the validation of three aspects: (1) burst pressure predictions from the BPVC, (2) strain predictions from Finite Element Analysis (FEA), and (3) deformation from FEA. The header prototypes were designed with geometry and weld specifications from the BPVC Section VIII Division 1, a design pressure typical of sCO2 service of 3,900 psi (26.9 MPa), and were built with 316 SS. Repeating the test in triplicate allows for greater confidence in the experimental results and enables data averaging. Burst pressure predictions are compared with experimental results for accuracy assessment. The prototypes are analyzed to understand their failure mechanism and locations. Experimental strain and deformation measurements were obtained optically with Digital Image Correlation (DIC). This technique allows strain to be measured in two dimensions and even allows for deformation measurements, all without contacting the prototype. Eight cameras are used for full coverage of both headers on the prototypes. The rich data from this technique are an excellent validation source for FEA strain and deformation predictions. Experimental data and simulation predictions are compared to assess simulation accuracy.
用于超临界CO2 (sCO2)应用的紧凑型热交换器通常设计为外部半圆形集管。它们的设计遵循ASME锅炉和压力容器规范(BPVC)，其方程通常由Castigliano定理推导。然而，没有已知的验证实验来支持他们的压力等级或破裂压力预测，也没有太多关于故障发生的方式和位置的信息。这项工作包括对三个半圆封头原型进行高压爆破，以验证三个方面:(1)BPVC的爆破压力预测，(2)有限元分析(FEA)的应变预测，(3)有限元分析的变形。首管原型设计符合BPVC Section VIII Division 1的几何形状和焊接规范，设计压力为sCO2服务的典型设计压力为3900 psi (26.9 MPa)，使用316 SS制造。重复三次测试可以提高实验结果的可信度，并实现数据平均。爆破压力预测结果与实验结果进行了比较，以评估其准确性。对原型进行了分析，以了解其失效机理和位置。实验应变和变形测量是通过数字图像相关(DIC)光学获得的。这种技术可以测量二维应变，甚至可以测量变形，所有这些都不需要接触原型。8个摄像头用于在原型上完全覆盖两个头。该技术的丰富数据是有限元应变和变形预测的良好验证来源。实验数据和模拟预测进行比较，以评估模拟精度。
{"title":"Compact Heat Exchanger Semi-Circular Header Burst Pressure and Strain Validation","authors":"B. Lance, M. Carlson","doi":"10.1115/gt2019-91772","DOIUrl":"https://doi.org/10.1115/gt2019-91772","url":null,"abstract":"\u0000 Compact heat exchangers for supercritical CO2 (sCO2) service are often designed with external, semi-circular headers. Their design is governed by the ASME Boiler & Pressure Vessel Code (BPVC) whose equations were typically derived by following Castigliano’s Theorems. However, there are no known validation experiments to support their claims of pressure rating or burst pressure predictions nor is there much information about how and where failures occur.\u0000 This work includes high pressure bursting of three semi-circular header prototypes for the validation of three aspects: (1) burst pressure predictions from the BPVC, (2) strain predictions from Finite Element Analysis (FEA), and (3) deformation from FEA. The header prototypes were designed with geometry and weld specifications from the BPVC Section VIII Division 1, a design pressure typical of sCO2 service of 3,900 psi (26.9 MPa), and were built with 316 SS. Repeating the test in triplicate allows for greater confidence in the experimental results and enables data averaging. Burst pressure predictions are compared with experimental results for accuracy assessment. The prototypes are analyzed to understand their failure mechanism and locations.\u0000 Experimental strain and deformation measurements were obtained optically with Digital Image Correlation (DIC). This technique allows strain to be measured in two dimensions and even allows for deformation measurements, all without contacting the prototype. Eight cameras are used for full coverage of both headers on the prototypes. The rich data from this technique are an excellent validation source for FEA strain and deformation predictions. Experimental data and simulation predictions are compared to assess simulation accuracy.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127780784","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}
J. Syblik, L. Vesely, S. Entler, Václav Dostál, J. Štěpánek
Cooling system is one of the most important part of the power plants and cooling systems based on S-CO2 (Supercritical Carbon Dioxide) coolant seems nowadays perspective alternative to Helium and Rankine steam power cycles. Due to many advantages of S-CO2, these cooling systems are researched on many institutions and the results confirm that it should be successful for the future cooling systems design. One of the main objectives is comparison of the possible cooling mediums of DEMO2 (Demonstration power plant 2) with focusing on different power cycles with S-CO2. The First part of this article targets on comparison of three main coolants: steam, helium and S-CO2. The second part of this article focuses on the new software called CCOCS (Cooling Cycles Optimization Computational Software) which was developed on CTU in Prague. This software works on deeper optimization of the power cycles with various coolants and initial conditions. The third part describes advanced S-CO2 power cycles and enlarges past research, which was based on optimization of S-CO2 Brayton Simple power cycle and S-CO2 Re-compression power cycle both with recuperation and their usage in fusion and Fission energy engineering. It is possible to heighten thermodynamic efficiency of power cycle by changing the layout of the power cycle and the main objective of this paper is to compare four advanced layouts, describe the results of the optimization of these cycles and outline advantages and disadvantages of chosen optimized layouts.
{"title":"Advanced S-CO2 Brayton Power Cycles in Nuclear and Fusion Energy","authors":"J. Syblik, L. Vesely, S. Entler, Václav Dostál, J. Štěpánek","doi":"10.1115/gt2019-90777","DOIUrl":"https://doi.org/10.1115/gt2019-90777","url":null,"abstract":"\u0000 Cooling system is one of the most important part of the power plants and cooling systems based on S-CO2 (Supercritical Carbon Dioxide) coolant seems nowadays perspective alternative to Helium and Rankine steam power cycles. Due to many advantages of S-CO2, these cooling systems are researched on many institutions and the results confirm that it should be successful for the future cooling systems design. One of the main objectives is comparison of the possible cooling mediums of DEMO2 (Demonstration power plant 2) with focusing on different power cycles with S-CO2. The First part of this article targets on comparison of three main coolants: steam, helium and S-CO2. The second part of this article focuses on the new software called CCOCS (Cooling Cycles Optimization Computational Software) which was developed on CTU in Prague. This software works on deeper optimization of the power cycles with various coolants and initial conditions. The third part describes advanced S-CO2 power cycles and enlarges past research, which was based on optimization of S-CO2 Brayton Simple power cycle and S-CO2 Re-compression power cycle both with recuperation and their usage in fusion and Fission energy engineering. It is possible to heighten thermodynamic efficiency of power cycle by changing the layout of the power cycle and the main objective of this paper is to compare four advanced layouts, describe the results of the optimization of these cycles and outline advantages and disadvantages of chosen optimized layouts.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132086591","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}
Nicola Aldi, N. Casari, Mirko Morini, M. Pinelli, P. R. Spina, A. Suman, Alessandro Vulpio
Energy and climate change policies associated with the continuous increase in natural gas costs pushed governments to invest in renewable energy and alternative fuels. In this perspective, the idea to convert gas turbines from natural gas to syngas from biomass gasification could be a suitable choice. Biogas is a valid alternative to natural gas because of its low costs, high availability and low environmental impact. Syngas is produced with the gasification of plant and animal wastes and then burnt in gas turbine combustor. Although synfuels are cleaned and filtered before entering the turbine combustor, impurities are not completely removed. Therefore, the high temperature reached in the turbine nozzle can lead to the deposition of contaminants onto internal surfaces. This phenomenon leads to the degradation of the hot parts of the gas turbine and consequently to the loss of performance. The amount of the deposited particles depends on mass flow rate, composition and ash content of the fuel and on turbine inlet temperature (TIT). Furthermore, compressor fouling plays a major role in the degradation of the gas turbine. In fact, particles that pass through the inlet filters, enter the compressor and could deposit on the airfoil. In this paper, the comparison between five (5) heavy-duty gas turbines is presented. The five machines cover an electrical power range from 1 MW to 10 MW. Every model has been simulated in six different climate zones and with four different synfuels. The combination of turbine fouling, compressor fouling, and environmental conditions is presented to show how these parameters can affect the performance and degradation of the machines. The results related to environmental influence are shown quantitatively, while those connected to turbine and compressor fouling are reported in a more qualitative manner. Particular attention is given also to part-load conditions. The power units are simulated in two different operating conditions: 100 % and 80 % of power rate. The influence of this variation on the intensity of fouling is also reported.
{"title":"Gas Turbine Fouling: The Influence of Climate and Part-Load Operating Conditions","authors":"Nicola Aldi, N. Casari, Mirko Morini, M. Pinelli, P. R. Spina, A. Suman, Alessandro Vulpio","doi":"10.1115/gt2019-91748","DOIUrl":"https://doi.org/10.1115/gt2019-91748","url":null,"abstract":"\u0000 Energy and climate change policies associated with the continuous increase in natural gas costs pushed governments to invest in renewable energy and alternative fuels. In this perspective, the idea to convert gas turbines from natural gas to syngas from biomass gasification could be a suitable choice. Biogas is a valid alternative to natural gas because of its low costs, high availability and low environmental impact. Syngas is produced with the gasification of plant and animal wastes and then burnt in gas turbine combustor. Although synfuels are cleaned and filtered before entering the turbine combustor, impurities are not completely removed. Therefore, the high temperature reached in the turbine nozzle can lead to the deposition of contaminants onto internal surfaces. This phenomenon leads to the degradation of the hot parts of the gas turbine and consequently to the loss of performance. The amount of the deposited particles depends on mass flow rate, composition and ash content of the fuel and on turbine inlet temperature (TIT). Furthermore, compressor fouling plays a major role in the degradation of the gas turbine. In fact, particles that pass through the inlet filters, enter the compressor and could deposit on the airfoil.\u0000 In this paper, the comparison between five (5) heavy-duty gas turbines is presented. The five machines cover an electrical power range from 1 MW to 10 MW. Every model has been simulated in six different climate zones and with four different synfuels. The combination of turbine fouling, compressor fouling, and environmental conditions is presented to show how these parameters can affect the performance and degradation of the machines. The results related to environmental influence are shown quantitatively, while those connected to turbine and compressor fouling are reported in a more qualitative manner.\u0000 Particular attention is given also to part-load conditions. The power units are simulated in two different operating conditions: 100 % and 80 % of power rate. The influence of this variation on the intensity of fouling is also reported.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121743487","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}
Nicola Aldi, N. Casari, Mirko Morini, M. Pinelli, P. R. Spina, A. Suman
Over recent decades, the variability and high costs of the traditional gas turbine fuels (e.g. natural gas), have pushed operators to consider low-grade fuels for running heavy-duty frames. Synfuels, obtained from coal, petroleum or biomass gasification, could represent valid alternatives in this sense. Although these alternatives match the reduction of costs and, in the case of biomass sources, would potentially provide a CO2 emission benefit (reduction of the CO2 capture and sequestration costs), these low-grade fuels have a higher content of contaminants. Synfuels are filtered before the combustor stage, but the contaminants are not removed completely. This fact leads to a considerable amount of deposition on the nozzle vanes due to the high temperature value. In addition to this, the continuous demand for increasing gas turbine efficiency, determines a higher combustor outlet temperature. Current advanced gas turbine engines operate at a turbine inlet temperature of (1400–1500) °C which is high enough to melt a high proportion of the contaminants introduced by low-grade fuels. Particle deposition can increase surface roughness, modify the airfoil shape and clog the coolant passages. At the same time, land based power units experience compressor fouling, due to the air contaminants able to pass through the filtration barriers. Hot sections and compressor fouling work together to determine performance degradation. This paper proposes an analysis of the contaminant deposition on hot gas turbine sections based on machine nameplate data. Hot section and compressor fouling are estimated using a fouling susceptibility criterion. The combination of gas turbine net power, efficiency and turbine inlet temperature (TIT) with different types of synfuel contaminants highlights how each gas turbine is subjected to particle deposition. The simulation of particle deposition on one hundred (100) gas turbines ranging from 1.2 MW to 420 MW was conducted following the fouling susceptibility criterion. Using a simplified particle deposition calculation based on TIT and contaminant viscosity estimation, the analysis shows how the correlation between type of contaminant and gas turbine performance plays a key role. The results allow the choice of the best heavy-duty frame as a function of the fuel. Low-efficiency frames (characterized by lower values of TIT) show the best compromise in order to reduce the effects of particle deposition in the presence of high-temperature melting contaminants. A high-efficiency frame is suitable when the contaminants are characterized by a low-melting point thanks to their lower fuel consumption.
{"title":"Gas Turbine Fouling: A Comparison Among One Hundred Heavy-Duty Frames","authors":"Nicola Aldi, N. Casari, Mirko Morini, M. Pinelli, P. R. Spina, A. Suman","doi":"10.1115/GT2018-76947","DOIUrl":"https://doi.org/10.1115/GT2018-76947","url":null,"abstract":"Over recent decades, the variability and high costs of the traditional gas turbine fuels (e.g. natural gas), have pushed operators to consider low-grade fuels for running heavy-duty frames. Synfuels, obtained from coal, petroleum or biomass gasification, could represent valid alternatives in this sense. Although these alternatives match the reduction of costs and, in the case of biomass sources, would potentially provide a CO2 emission benefit (reduction of the CO2 capture and sequestration costs), these low-grade fuels have a higher content of contaminants. Synfuels are filtered before the combustor stage, but the contaminants are not removed completely. This fact leads to a considerable amount of deposition on the nozzle vanes due to the high temperature value. In addition to this, the continuous demand for increasing gas turbine efficiency, determines a higher combustor outlet temperature. Current advanced gas turbine engines operate at a turbine inlet temperature of (1400–1500) °C which is high enough to melt a high proportion of the contaminants introduced by low-grade fuels. Particle deposition can increase surface roughness, modify the airfoil shape and clog the coolant passages. At the same time, land based power units experience compressor fouling, due to the air contaminants able to pass through the filtration barriers. Hot sections and compressor fouling work together to determine performance degradation.\u0000 This paper proposes an analysis of the contaminant deposition on hot gas turbine sections based on machine nameplate data. Hot section and compressor fouling are estimated using a fouling susceptibility criterion. The combination of gas turbine net power, efficiency and turbine inlet temperature (TIT) with different types of synfuel contaminants highlights how each gas turbine is subjected to particle deposition. The simulation of particle deposition on one hundred (100) gas turbines ranging from 1.2 MW to 420 MW was conducted following the fouling susceptibility criterion. Using a simplified particle deposition calculation based on TIT and contaminant viscosity estimation, the analysis shows how the correlation between type of contaminant and gas turbine performance plays a key role.\u0000 The results allow the choice of the best heavy-duty frame as a function of the fuel. Low-efficiency frames (characterized by lower values of TIT) show the best compromise in order to reduce the effects of particle deposition in the presence of high-temperature melting contaminants. A high-efficiency frame is suitable when the contaminants are characterized by a low-melting point thanks to their lower fuel consumption.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"192 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124268618","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}
Owen M. Pryor, Subith S. Vasu, Xijia Lu, D. Freed, B. Forrest
There has been some recent work on the global kinetic modeling of flames in oxy-fuel combustion for methane. The main challenge is that none of the mechanisms were developed to understand the time-scales of ignition. Here, a 3-step mechanism was developed for methane combustion in oxy-fuel environment. The mechanisms were simulated using a closed batch homogeneous batch reactor with constant pressure and compared to baseline simulations performed using a detailed mechanism. All simulations were performed for methane used a mixture of XCH4 = 0.05, XO2 = 0.10 and XCO2 = 0.85. Mechanisms were altered using the global mechanism equilibrium approach to ensure that the steady-state values matched the reference values and were further altered using an optimization scheme to match experimental data that was taken in a shock tube. Simulation results of methane, CO time-histories, and temperature profiles from the global mechanism were compared to those from the detailed mechanism. Ignition delay times were used to represent the time-scales of combustion. This was defined for current simulations as the time required for methane concentration to reach 5% of its initial value during combustion. Using this approach, the 3-step methane combustion mechanism showed excellent improvement in the ignition timing over a range of pressures (1 to 10 bar) and initial temperatures (1500 to 2000 K) for both lean and stoichiometric mixtures but fails to predict ignition delay times at 30 bar or the ignition delay times of fuel rich mixtures. Ongoing effort focuses on extending this new global mechanism to higher pressures and to syngas mixtures.
{"title":"Development of a Global Mechanism for Oxy-Methane Combustion in a CO2 Environment","authors":"Owen M. Pryor, Subith S. Vasu, Xijia Lu, D. Freed, B. Forrest","doi":"10.1115/GT2018-75169","DOIUrl":"https://doi.org/10.1115/GT2018-75169","url":null,"abstract":"There has been some recent work on the global kinetic modeling of flames in oxy-fuel combustion for methane. The main challenge is that none of the mechanisms were developed to understand the time-scales of ignition. Here, a 3-step mechanism was developed for methane combustion in oxy-fuel environment. The mechanisms were simulated using a closed batch homogeneous batch reactor with constant pressure and compared to baseline simulations performed using a detailed mechanism. All simulations were performed for methane used a mixture of XCH4 = 0.05, XO2 = 0.10 and XCO2 = 0.85. Mechanisms were altered using the global mechanism equilibrium approach to ensure that the steady-state values matched the reference values and were further altered using an optimization scheme to match experimental data that was taken in a shock tube. Simulation results of methane, CO time-histories, and temperature profiles from the global mechanism were compared to those from the detailed mechanism. Ignition delay times were used to represent the time-scales of combustion. This was defined for current simulations as the time required for methane concentration to reach 5% of its initial value during combustion. Using this approach, the 3-step methane combustion mechanism showed excellent improvement in the ignition timing over a range of pressures (1 to 10 bar) and initial temperatures (1500 to 2000 K) for both lean and stoichiometric mixtures but fails to predict ignition delay times at 30 bar or the ignition delay times of fuel rich mixtures. Ongoing effort focuses on extending this new global mechanism to higher pressures and to syngas mixtures.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123717224","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}
Junhyun Cho, Hyungki Shin, Jongjae Cho, H. Ra, C. Roh, Beomjoon Lee, Gilbong Lee, Bongsu Choi, Y. Baik
In order to overcome reported failure problems of turbomachinery for the supercritical carbon dioxide power cycle induced by the high rotational speed and axial force, an axial impulse-type turbo-generator with a partial admission nozzle was designed and manufactured to reduce the rotational speed and axial force. The turbine wheel part was separated by carbon ring-type mechanical seals to use conventional oillubricated tilting-pad bearings. A simple transcritical cycle using a liquid CO2 pump was constructed to drive the turbogenerator. A 600,000 kcal/h LNG fired thermal oil boiler and 200 RT chiller were used as a heat source and heat sink. The target turbine inlet temperature and pressure were 200°C and 130 bar, respectively. Two printed circuit heat exchangers were manufactured for both sides of the heater and cooler. A leakage make-up system using a reciprocating CO2 compressor; CO2 supply valve-train to the main loop and mechanical seal; and an oil cooler for the bearings, load bank, and control systems were installed. Prior to the turbine power-generating operation, a turbine bypass loop was operated using an air-driven control valve to determine the system mass flow rate and create turbine inlet conditions. Then, 11 kW of electric power was obtained under 205°C and 100 bar turbine inlet conditions, and the continuous operating time was 45 min.
{"title":"Development and Operation of Supercritical Carbon Dioxide Power Cycle Test Loop With Axial Turbo-Generator","authors":"Junhyun Cho, Hyungki Shin, Jongjae Cho, H. Ra, C. Roh, Beomjoon Lee, Gilbong Lee, Bongsu Choi, Y. Baik","doi":"10.1115/GT2018-76488","DOIUrl":"https://doi.org/10.1115/GT2018-76488","url":null,"abstract":"In order to overcome reported failure problems of turbomachinery for the supercritical carbon dioxide power cycle induced by the high rotational speed and axial force, an axial impulse-type turbo-generator with a partial admission nozzle was designed and manufactured to reduce the rotational speed and axial force. The turbine wheel part was separated by carbon ring-type mechanical seals to use conventional oillubricated tilting-pad bearings. A simple transcritical cycle using a liquid CO2 pump was constructed to drive the turbogenerator. A 600,000 kcal/h LNG fired thermal oil boiler and 200 RT chiller were used as a heat source and heat sink. The target turbine inlet temperature and pressure were 200°C and 130 bar, respectively. Two printed circuit heat exchangers were manufactured for both sides of the heater and cooler. A leakage make-up system using a reciprocating CO2 compressor; CO2 supply valve-train to the main loop and mechanical seal; and an oil cooler for the bearings, load bank, and control systems were installed. Prior to the turbine power-generating operation, a turbine bypass loop was operated using an air-driven control valve to determine the system mass flow rate and create turbine inlet conditions. Then, 11 kW of electric power was obtained under 205°C and 100 bar turbine inlet conditions, and the continuous operating time was 45 min.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128263651","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 Saverin, D. Marten, G. Pechlivanoglou, C. Paschereit, A. V. Garrel
A method for the treatment of the evolution of the wake of aerodynamic bodies has been implemented. A vortex particle method approach has been used whereby the flow field is discretized into numerical volumes which possess a given circulation. A lifting line formulation is used to determine the circulation of the trailing and shed vortex elements. Upon their release vortex particles are allowed to freely convect under the action of the blade, the freestream and other particles. Induced velocities are calculated with a regularized form of the Biot-Savart kernel, adapted for vortex particles. Vortex trajectories are integrated in a Lagrangian sense. Provision is made in the model for the rate of change of the circulation vector and for viscous particle interaction; however these features are not exploited in this work. The validity of the model is tested by comparing results of the numerical simulation to the experimental measurements of the Mexico rotor. A range of tip speed ratios are investigated and the blade loading and induced wake velocities are compared to experiment and finite-volume numerical models. The computational expense of this method scales quadratically with the number of released wake particles N. This results in an unacceptable computational expense after a limited simulation time. A recently developed multilevel algorithm has been implemented to overcome this computational expense. This method approximates the Biot-Savart kernel in the far field by using polynomial interpolation onto a structured grid node system. The error of this approximation is seen to be arbitrarily controlled by the polynomial order of the interpolation. It is demonstrated that by using this method the computational expense scales linearly. The model’s ability to quickly produce results of comparable accuracy to finite volume simulations is illustrated and emphasizes the opportunity for industry to move from low fidelity, less accurate blade-element-momentum methods towards higher fidelity free vortex wake models while keeping the advantage of short problem turnaround times.
{"title":"Implementation of the Multi-Level Multi-Integration Cluster Method to the Treatment of Vortex Particle Interactions for Fast Wind Turbine Wake Simulations","authors":"Joseph Saverin, D. Marten, G. Pechlivanoglou, C. Paschereit, A. V. Garrel","doi":"10.1115/GT2018-76554","DOIUrl":"https://doi.org/10.1115/GT2018-76554","url":null,"abstract":"A method for the treatment of the evolution of the wake of aerodynamic bodies has been implemented. A vortex particle method approach has been used whereby the flow field is discretized into numerical volumes which possess a given circulation. A lifting line formulation is used to determine the circulation of the trailing and shed vortex elements. Upon their release vortex particles are allowed to freely convect under the action of the blade, the freestream and other particles. Induced velocities are calculated with a regularized form of the Biot-Savart kernel, adapted for vortex particles. Vortex trajectories are integrated in a Lagrangian sense. Provision is made in the model for the rate of change of the circulation vector and for viscous particle interaction; however these features are not exploited in this work. The validity of the model is tested by comparing results of the numerical simulation to the experimental measurements of the Mexico rotor. A range of tip speed ratios are investigated and the blade loading and induced wake velocities are compared to experiment and finite-volume numerical models.\u0000 The computational expense of this method scales quadratically with the number of released wake particles N. This results in an unacceptable computational expense after a limited simulation time. A recently developed multilevel algorithm has been implemented to overcome this computational expense. This method approximates the Biot-Savart kernel in the far field by using polynomial interpolation onto a structured grid node system. The error of this approximation is seen to be arbitrarily controlled by the polynomial order of the interpolation. It is demonstrated that by using this method the computational expense scales linearly. The model’s ability to quickly produce results of comparable accuracy to finite volume simulations is illustrated and emphasizes the opportunity for industry to move from low fidelity, less accurate blade-element-momentum methods towards higher fidelity free vortex wake models while keeping the advantage of short problem turnaround times.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129349604","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}
The supercritical CO2 gas turbine is considered to achieve a high cycle efficiency by reducing compressor work near the critical point. But test loops made by international community show that the performance of the compressor is still quite far from the target at the design point. The paper focuses on the influence of relative velocity ratio on the performances of centrifugal impellers operating with real gas CO2 and ideal gas CO2. At the same time, comparisons between characteristic curves of impellers operating at near critical, supercritical, and subcritical inlet condition with real gas CO2 are also demonstrated. Relative velocity ratio demonstrates the same trend with real and ideal gas CO2 in the same impeller, but the specific value is different. Impellers with real gas CO2 could achieve a high isentropic efficiency when relative velocity ratio is in the range of 1.05∼1.5. The results show that relative velocity ratio plays an important role in compressor performance.
{"title":"Influence of Relative Velocity Ratio on Centrifugal Impellers Operating With Supercritical CO2","authors":"Haiqing Liu, Zhongran Chi, S. Zang","doi":"10.1115/GT2018-75590","DOIUrl":"https://doi.org/10.1115/GT2018-75590","url":null,"abstract":"The supercritical CO2 gas turbine is considered to achieve a high cycle efficiency by reducing compressor work near the critical point. But test loops made by international community show that the performance of the compressor is still quite far from the target at the design point. The paper focuses on the influence of relative velocity ratio on the performances of centrifugal impellers operating with real gas CO2 and ideal gas CO2. At the same time, comparisons between characteristic curves of impellers operating at near critical, supercritical, and subcritical inlet condition with real gas CO2 are also demonstrated. Relative velocity ratio demonstrates the same trend with real and ideal gas CO2 in the same impeller, but the specific value is different. Impellers with real gas CO2 could achieve a high isentropic efficiency when relative velocity ratio is in the range of 1.05∼1.5. The results show that relative velocity ratio plays an important role in compressor performance.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129109680","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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