Constantin Kiesling, Matheus Marques da Silva, Martin Kober, Andreas Wimmer, Jan Duesing, Gunther Hager
This paper deals with research work related to advanced sensor technology that is highly integrated into sliding bearings so that information is obtained nearly directly from relevant areas such as the bearing running layer and the lubrication gap. An isolated, sputtered sensor layer with a thickness of a few micrometers is employed in combination with a laser structuring process to form the desired thin film sensor structure below the bearing running surface. While several measurement parameters and corresponding sensor types are conceivable, this paper focuses on temperature and strain measurements that rely on a change in the electrical resistance of the sensor layer material. Promising sensor layouts and positions targeted for use in condition monitoring applications in ICEs are elaborated in detail. Developments and challenges in implementing the sensor technology concept - in particular with regard to the process of manufacturing the sensor as well as the wire contacting - are outlined in depth. The paper concludes by presenting measurement results obtained with this sensor technology at lab scale as well as an outlook towards implementing the instrumented bearings in ICEs. (the abstract has been shortened for the web input form, please find the complete abstract included in the submitted publication manuscript)
{"title":"Laser-Structured Thin Film Sensor Technology for Sliding Bearings in Internal Combustion Engines","authors":"Constantin Kiesling, Matheus Marques da Silva, Martin Kober, Andreas Wimmer, Jan Duesing, Gunther Hager","doi":"10.1115/1.4064451","DOIUrl":"https://doi.org/10.1115/1.4064451","url":null,"abstract":"\u0000 This paper deals with research work related to advanced sensor technology that is highly integrated into sliding bearings so that information is obtained nearly directly from relevant areas such as the bearing running layer and the lubrication gap. An isolated, sputtered sensor layer with a thickness of a few micrometers is employed in combination with a laser structuring process to form the desired thin film sensor structure below the bearing running surface. While several measurement parameters and corresponding sensor types are conceivable, this paper focuses on temperature and strain measurements that rely on a change in the electrical resistance of the sensor layer material. Promising sensor layouts and positions targeted for use in condition monitoring applications in ICEs are elaborated in detail. Developments and challenges in implementing the sensor technology concept - in particular with regard to the process of manufacturing the sensor as well as the wire contacting - are outlined in depth. The paper concludes by presenting measurement results obtained with this sensor technology at lab scale as well as an outlook towards implementing the instrumented bearings in ICEs. (the abstract has been shortened for the web input form, please find the complete abstract included in the submitted publication manuscript)","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139439459","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}
Pedro Piqueras, J. de la Morena, E. Sanchis, Carla Conde
New generations of spark-ignition engines include exhaust gas recirculation (EGR) to improve the engine efficiency. Depending on the design of the EGR routing, some differences in the total amount of recirculated gases that reach each cylinder can be induced. This affects the air-to-fuel ratio on each cylinder due to the combination of the different temperature and composition of the gases at the intake valve closure. As a consequence, significant deviations in the combustion process and the subsequent composition upstream the three-way catalyst can be reached. This paper explores these effects on catalyst performance and tailpipe emissions, individualizing the behavior for each regulated species. The study was performed in a 4-cylinder naturally aspirated engine with Atkinson cycle and a close-coupled three-way catalyst. The most significant deterioration in conversion efficiency appeared for the nitrogen oxides, directly linked to the EGR dispersion level. In the case of CO emissions, no significant impact was observed except at high average EGR rates, where one or more of the cylinders exceeded the EGR tolerance for that speed and load. Based on these results, a strategy where the fuel injector command is adapted to correct the air-to-fuel ratio deviations induced by the EGR was developed and implemented
{"title":"Impact of Cylinder-To-Cylinder Dispersion of Exhaust Gas Recirculation On the Three-Way Catalyst Performance and Tailpipe Emissions of Spark-Ignition Engines","authors":"Pedro Piqueras, J. de la Morena, E. Sanchis, Carla Conde","doi":"10.1115/1.4064452","DOIUrl":"https://doi.org/10.1115/1.4064452","url":null,"abstract":"\u0000 New generations of spark-ignition engines include exhaust gas recirculation (EGR) to improve the engine efficiency. Depending on the design of the EGR routing, some differences in the total amount of recirculated gases that reach each cylinder can be induced. This affects the air-to-fuel ratio on each cylinder due to the combination of the different temperature and composition of the gases at the intake valve closure. As a consequence, significant deviations in the combustion process and the subsequent composition upstream the three-way catalyst can be reached. This paper explores these effects on catalyst performance and tailpipe emissions, individualizing the behavior for each regulated species. The study was performed in a 4-cylinder naturally aspirated engine with Atkinson cycle and a close-coupled three-way catalyst. The most significant deterioration in conversion efficiency appeared for the nitrogen oxides, directly linked to the EGR dispersion level. In the case of CO emissions, no significant impact was observed except at high average EGR rates, where one or more of the cylinders exceeded the EGR tolerance for that speed and load. Based on these results, a strategy where the fuel injector command is adapted to correct the air-to-fuel ratio deviations induced by the EGR was developed and implemented","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139439572","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}
Osama Nsaif, S. Kokjohn, Randy Hessel, Adam Dempsey
The oil and gas industry heavily relies on lean burn spark ignited natural gas reciprocating engines. These engines produce pollutants, such as NOx and CO, but due to their premixed nature, also produce relatively large amounts of unburned methane (CH4) emissions. The primary source of methane emissions in lean burn engines are the crevices and near wall quench layers. Thus, one method to dramatically reduce methane emissions is to alter the combustion to be non-premixed, mixing-controlled combustion. In this concept the active prechamber acts as a reliable ignition source for the direct injected natural gas, which is referred to as prechamber ignited mixing-controlled combustion (PC-MCC). The PC-MCC concept enables a ~10x reduction in methane emissions, making it a promising technology for reducing the environmental impact of reciprocating engines. In this study, CFD simulations have been used to compare two modeling approaches for PC-MCC: a pure Eulerian gaseous injection approach and a gas-parcels injection method. Using the parcel method to model the gas injection enables an engineering approach to study and design the PC-MCC concept in a timely manner with coarser computational grids. This study also investigated the impact of several variables that may contribute to the performance and emissions of the PC-MCC strategy. The parameters that were examined include prechamber passageway characteristics like nozzle diameter, number of nozzles, and the orientation of nozzle orifices.
{"title":"Reducing Methane Emissions From Lean Burn Natural Gas Engines with Prechamber Ignited Mixing-Controlled Combustion","authors":"Osama Nsaif, S. Kokjohn, Randy Hessel, Adam Dempsey","doi":"10.1115/1.4064454","DOIUrl":"https://doi.org/10.1115/1.4064454","url":null,"abstract":"\u0000 The oil and gas industry heavily relies on lean burn spark ignited natural gas reciprocating engines. These engines produce pollutants, such as NOx and CO, but due to their premixed nature, also produce relatively large amounts of unburned methane (CH4) emissions. The primary source of methane emissions in lean burn engines are the crevices and near wall quench layers. Thus, one method to dramatically reduce methane emissions is to alter the combustion to be non-premixed, mixing-controlled combustion. In this concept the active prechamber acts as a reliable ignition source for the direct injected natural gas, which is referred to as prechamber ignited mixing-controlled combustion (PC-MCC). The PC-MCC concept enables a ~10x reduction in methane emissions, making it a promising technology for reducing the environmental impact of reciprocating engines. In this study, CFD simulations have been used to compare two modeling approaches for PC-MCC: a pure Eulerian gaseous injection approach and a gas-parcels injection method. Using the parcel method to model the gas injection enables an engineering approach to study and design the PC-MCC concept in a timely manner with coarser computational grids. This study also investigated the impact of several variables that may contribute to the performance and emissions of the PC-MCC strategy. The parameters that were examined include prechamber passageway characteristics like nozzle diameter, number of nozzles, and the orientation of nozzle orifices.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139444097","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}
Chad Koci, Radoslav Ivanov, Jay Steffen, Jeremy Adams, R. Kruiswyk, Tim Bazyn, Lauren Duvall, R. McDavid, Marc Montgomery, Jason Keim, Tom Waldron
A multi-year power system R&D program was completed with the objective of developing an off-road hybrid heavy duty diesel engine with front end accessory drive-integrated energy storage. This system was validated to deliver 10.5 - 25.6% reduction in fuel consumption over current Tier 4 Final-based 18L diesel engines, over various off-road machine application cycles. The power system consisted of a downsized heavy-duty diesel 13L engine containing advanced combustion technologies, capable of elevated peak cylinder pressures and thermal efficiencies, thermal barrier coatings, exhaust waste heat recovery via SuperTurbo™ turbocompounding, and hybrid energy assisting and recovery through both mechanical and electrical systems. Following the concept definition, design, and analysis phases of the program, the final phase focused on building and validating the performance and efficiency in laboratory tests. While aspects of the system such as start/stop and reduced off-road cooling package energy losses were only analytically evaluated, the main 13L concept engine with full hybrid system was successfully built and tested in steady-state and in transient certification and real-world application cycles. Extensive simulations in Caterpillar's DYNASTY™ software environment utilized the validation test data to assess performance more fully and confidently over varied cycles and strategies. An average fuel consumption reduction of 17.9% was realized, and the majority (~13%) of the benefit stemmed from the core concept 13L engine. To conclude, a total cost of ownership analysis provides context to commercial viability and where adoption focus should be placed.
{"title":"A Hybrid Heavy Duty Diesel Power System for Off-Road Applications - Concept Validation","authors":"Chad Koci, Radoslav Ivanov, Jay Steffen, Jeremy Adams, R. Kruiswyk, Tim Bazyn, Lauren Duvall, R. McDavid, Marc Montgomery, Jason Keim, Tom Waldron","doi":"10.1115/1.4064455","DOIUrl":"https://doi.org/10.1115/1.4064455","url":null,"abstract":"\u0000 A multi-year power system R&D program was completed with the objective of developing an off-road hybrid heavy duty diesel engine with front end accessory drive-integrated energy storage. This system was validated to deliver 10.5 - 25.6% reduction in fuel consumption over current Tier 4 Final-based 18L diesel engines, over various off-road machine application cycles. The power system consisted of a downsized heavy-duty diesel 13L engine containing advanced combustion technologies, capable of elevated peak cylinder pressures and thermal efficiencies, thermal barrier coatings, exhaust waste heat recovery via SuperTurbo™ turbocompounding, and hybrid energy assisting and recovery through both mechanical and electrical systems. Following the concept definition, design, and analysis phases of the program, the final phase focused on building and validating the performance and efficiency in laboratory tests. While aspects of the system such as start/stop and reduced off-road cooling package energy losses were only analytically evaluated, the main 13L concept engine with full hybrid system was successfully built and tested in steady-state and in transient certification and real-world application cycles. Extensive simulations in Caterpillar's DYNASTY™ software environment utilized the validation test data to assess performance more fully and confidently over varied cycles and strategies. An average fuel consumption reduction of 17.9% was realized, and the majority (~13%) of the benefit stemmed from the core concept 13L engine. To conclude, a total cost of ownership analysis provides context to commercial viability and where adoption focus should be placed.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139442061","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 numerical study focuses on the characterization of prechamber enabled mixing-controlled combustion (PC-MCC) at ~18 bar brake mean effective pressure (BMEP) and 2200 rpm with 10% by volume ethanol-gasoline blend (E10) and pure ethanol (E100). Computational fluid dynamic (CFD) simulations of a stock and prechamber retrofitted single-cylinder Caterpillar C9.3B are carried out using CONVERGE. Prechamber equivalence ratio at spark timing, prechamber spark timing advance, and main chamber injection strategy are assessed with respect to their impact on ignition assistance performance and emissions characteristics relative to a diesel baseline at the same boundary conditions. Simulation results indicate that PC-MCC is flex-fuel capable and operates well for both E10 and E100 at the operating conditions considered. The results demonstrate that the use of a pilot-main injection strategy enables spark timing in the prechamber to be advanced and thus reduce spark plug firing pressure while maintaining robust ignition assistance. Results also indicate that the rich prechamber operation is favored for improved ignition assistance capabilities. The findings of this work suggest that a heavy-duty vehicle using a PC-MCC engine can utilize any blend of gasoline and ethanol, up to including pure ethanol, with no major sacrifices in performance relative to the diesel engine.
{"title":"Characterization of Flex-Fuel Prechamber Enabled Mixing-Controlled Combustion (PC-MCC) with Gasoline/Ethanol Blends at High Load","authors":"J. Zeman, Adam Dempsey","doi":"10.1115/1.4064453","DOIUrl":"https://doi.org/10.1115/1.4064453","url":null,"abstract":"\u0000 This numerical study focuses on the characterization of prechamber enabled mixing-controlled combustion (PC-MCC) at ~18 bar brake mean effective pressure (BMEP) and 2200 rpm with 10% by volume ethanol-gasoline blend (E10) and pure ethanol (E100). Computational fluid dynamic (CFD) simulations of a stock and prechamber retrofitted single-cylinder Caterpillar C9.3B are carried out using CONVERGE. Prechamber equivalence ratio at spark timing, prechamber spark timing advance, and main chamber injection strategy are assessed with respect to their impact on ignition assistance performance and emissions characteristics relative to a diesel baseline at the same boundary conditions. Simulation results indicate that PC-MCC is flex-fuel capable and operates well for both E10 and E100 at the operating conditions considered. The results demonstrate that the use of a pilot-main injection strategy enables spark timing in the prechamber to be advanced and thus reduce spark plug firing pressure while maintaining robust ignition assistance. Results also indicate that the rich prechamber operation is favored for improved ignition assistance capabilities. The findings of this work suggest that a heavy-duty vehicle using a PC-MCC engine can utilize any blend of gasoline and ethanol, up to including pure ethanol, with no major sacrifices in performance relative to the diesel engine.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139444068","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 parametric vibration and combined resonance of a turbine blade with a pre-set angle subjected to the combined effect of parametric and forced excitation were investigated. The blade was modeled as a rotating beam considering the effects of centrifugal, gyroscopic, and bending-torsion coupling. The instability region of the corresponding linear system with parametric excitation was analyzed using Floquet theory, and the effect of blade parameters on this region was discussed. Notably, the parametric vibration of the torsional degree of freedom caused by parametric excitation of the bending degree of freedom has been found. The results show that the size and position of the parameter resonance region are affected by the blade aspect ratio and preset angle, respectively. Furthermore, the multi-scale method was employed to solve the blade equation under the combined action of parametric and forced excitation to study the combined resonance caused by forced excitation and gyroscopic item. The effect of blade parameters and excitation characteristics on regions of combined resonance were investigated. The phenomenon of heteroclinic bifurcation was observed due to changes in the excitation frequency, and the harmonic components that accompanied the bifurcation changed. Specifically, a multi-period response dominated by the excitation frequency and subharmonic components shifted to a single-period response dominated by subharmonic components. This study provides a theoretical explanation for the non-synchronous resonance of blades and the subharmonic signals in blade vibration and guides blade parameter design, especially for wind turbines.
{"title":"Parametric Vibration and Combined Resonance of A Bending-Torsional Coupled Turbine Blade With A Pre-Set Angle","authors":"Yuankai Ren, Jianwei Lu, Gaoming Deng, DingHua Zhou","doi":"10.1115/1.4064438","DOIUrl":"https://doi.org/10.1115/1.4064438","url":null,"abstract":"\u0000 The parametric vibration and combined resonance of a turbine blade with a pre-set angle subjected to the combined effect of parametric and forced excitation were investigated. The blade was modeled as a rotating beam considering the effects of centrifugal, gyroscopic, and bending-torsion coupling. The instability region of the corresponding linear system with parametric excitation was analyzed using Floquet theory, and the effect of blade parameters on this region was discussed. Notably, the parametric vibration of the torsional degree of freedom caused by parametric excitation of the bending degree of freedom has been found. The results show that the size and position of the parameter resonance region are affected by the blade aspect ratio and preset angle, respectively. Furthermore, the multi-scale method was employed to solve the blade equation under the combined action of parametric and forced excitation to study the combined resonance caused by forced excitation and gyroscopic item. The effect of blade parameters and excitation characteristics on regions of combined resonance were investigated. The phenomenon of heteroclinic bifurcation was observed due to changes in the excitation frequency, and the harmonic components that accompanied the bifurcation changed. Specifically, a multi-period response dominated by the excitation frequency and subharmonic components shifted to a single-period response dominated by subharmonic components. This study provides a theoretical explanation for the non-synchronous resonance of blades and the subharmonic signals in blade vibration and guides blade parameter design, especially for wind turbines.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139443506","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 concept of electrified aircraft propulsion (EAP) has been proposed and researched widely due to its potential for reduction of fuel burn, emissions and noise. Current studies main focus on the single concept or point design rather than a systematic design and verification exploration. This paper considers whether the given mission is met as evaluation criterion and proposed a mission-oriented design and verification method using Model-based Systems Engineering (MBSE). Instead of using a general modeling language, this method develops a domain-specific meta model library based on six meta-meta models for EAP. A Mission-Operational-Functional-Logical-Physical (MOFLP) modeling methodology is proposed to standardize EAP design process. In addition, the modeling process is integrated with the verification process by executable verification script. In order to verify the effectiveness of this method, a case study about skydiving mission is conducted. The case results show that this method can obtain the initial EAP solution and verify it. Such initial solution can serve as a baseline for subsequent iterative designs.
{"title":"Mission-Oriented Electrified Aircraft Propulsion System Design and Verification Using Model-Based Systems Engineering","authors":"Zhenchao Hu, Jinwei Chen, Jinzhi Lu, Huisheng Zhang","doi":"10.1115/1.4064411","DOIUrl":"https://doi.org/10.1115/1.4064411","url":null,"abstract":"\u0000 The concept of electrified aircraft propulsion (EAP) has been proposed and researched widely due to its potential for reduction of fuel burn, emissions and noise. Current studies main focus on the single concept or point design rather than a systematic design and verification exploration. This paper considers whether the given mission is met as evaluation criterion and proposed a mission-oriented design and verification method using Model-based Systems Engineering (MBSE). Instead of using a general modeling language, this method develops a domain-specific meta model library based on six meta-meta models for EAP. A Mission-Operational-Functional-Logical-Physical (MOFLP) modeling methodology is proposed to standardize EAP design process. In addition, the modeling process is integrated with the verification process by executable verification script. In order to verify the effectiveness of this method, a case study about skydiving mission is conducted. The case results show that this method can obtain the initial EAP solution and verify it. Such initial solution can serve as a baseline for subsequent iterative designs.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139380496","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}
In this study, the ORC and hybrid absorption recompression cycle have been modified by the addition of turbine bleeding with regeneration and ejector, making it a unique solar-powered trigeneration system. With this modification, the useful electric power increases by 65 kW due to increased mass flow rate and overall efficiency nearly by 0.7%, and this difference grows as DNI rises. After identifying these improvements, a parametric study was conducted to determine the optimum value of these operating variables, such as direct normal irradiation, condenser pressure, turbine inlet temperature, and pressure ratio, based on the desired outputs and efficiencies of the proposed modified systems. The results indicate that the proposed system is capable of simultaneously generating 315.3 kW of electric power, 1588 kW of heating output, and 501.6 kW of cooling at energy and exergy efficiencies of 80.8% and 25.36%, respectively. Further, in terms of energy one could conclude that only 19.2 % of total available energy is getting wasted, but in reality, around 75% of the work potential of the input exergy is getting wasted. The maximum exergy is lost at the solar collector and destructed at HRVG, hence requiring careful design to improve their performance. Lastly, an economic analysis of the proposed system has also been conducted, and the payback period is found to be 2.33 years, which ensures its economic viability.
{"title":"Thermo-Economic Analysis of Solar-Powered Trigeneration System with Integrated Ejector-Absorption Recompression and Modified Organic Rankine Cycle","authors":"Shubham Kumar Mishra, Amrit Rehalia, Ashutosh Kumar Verma, Laxmikant Yadav","doi":"10.1115/1.4064439","DOIUrl":"https://doi.org/10.1115/1.4064439","url":null,"abstract":"\u0000 In this study, the ORC and hybrid absorption recompression cycle have been modified by the addition of turbine bleeding with regeneration and ejector, making it a unique solar-powered trigeneration system. With this modification, the useful electric power increases by 65 kW due to increased mass flow rate and overall efficiency nearly by 0.7%, and this difference grows as DNI rises. After identifying these improvements, a parametric study was conducted to determine the optimum value of these operating variables, such as direct normal irradiation, condenser pressure, turbine inlet temperature, and pressure ratio, based on the desired outputs and efficiencies of the proposed modified systems. The results indicate that the proposed system is capable of simultaneously generating 315.3 kW of electric power, 1588 kW of heating output, and 501.6 kW of cooling at energy and exergy efficiencies of 80.8% and 25.36%, respectively. Further, in terms of energy one could conclude that only 19.2 % of total available energy is getting wasted, but in reality, around 75% of the work potential of the input exergy is getting wasted. The maximum exergy is lost at the solar collector and destructed at HRVG, hence requiring careful design to improve their performance. Lastly, an economic analysis of the proposed system has also been conducted, and the payback period is found to be 2.33 years, which ensures its economic viability.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139380773","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}
In Part I, a companion paper of the two-part article, a subsonic tur-bine stage and a transonic one conditioned at the same Reynolds number, flow coefficient, loading coefficient and reaction, but two different exit Mach numbers are designed to provide a direct contrast between a high-subsonic and a transonic flow conditioning for rotor blade squealer tips. In the present paper as Part II, further analyses are carried out to address the main issues of interest arising from Part I: firstly, to identify the driving flow physical mechanisms for the contrasting aerodynamic efficiency sensitivities of the two stages; and secondly to seek a more suitable heat transfer objective function for the tip aero-thermal design optimization, given the seemingly strong conflicts among those conventionally adopted heat transfer objective functions. Two counter-rotating tip vortical structures, the pressure side vortex (PSV) and the casing-driven cavity vortex (CCV), are shown to impact the aero-performance differently between the two stages. For the subsonic stage, the leakage flow is strongly affected by a stronger residual PSV at the squealer cavity exit. For the transonic stage however, the tip choking in limiting the OTL mass flow and favorable pressure gradient in a transonic flow over a separation bubble led to a much stronger and more persistent CCV and thus lower aerodynamic effectiveness of squealer tip for the transonic stage.
{"title":"Design Optimization of Blade Tip in Subsonic and Transonic Turbine Stages - Part II: Flow Physics and Augmented Aerothermal Integral Objective Function","authors":"PH Duan, L. He","doi":"10.1115/1.4064326","DOIUrl":"https://doi.org/10.1115/1.4064326","url":null,"abstract":"In Part I, a companion paper of the two-part article, a subsonic tur-bine stage and a transonic one conditioned at the same Reynolds number, flow coefficient, loading coefficient and reaction, but two different exit Mach numbers are designed to provide a direct contrast between a high-subsonic and a transonic flow conditioning for rotor blade squealer tips. In the present paper as Part II, further analyses are carried out to address the main issues of interest arising from Part I: firstly, to identify the driving flow physical mechanisms for the contrasting aerodynamic efficiency sensitivities of the two stages; and secondly to seek a more suitable heat transfer objective function for the tip aero-thermal design optimization, given the seemingly strong conflicts among those conventionally adopted heat transfer objective functions. Two counter-rotating tip vortical structures, the pressure side vortex (PSV) and the casing-driven cavity vortex (CCV), are shown to impact the aero-performance differently between the two stages. For the subsonic stage, the leakage flow is strongly affected by a stronger residual PSV at the squealer cavity exit. For the transonic stage however, the tip choking in limiting the OTL mass flow and favorable pressure gradient in a transonic flow over a separation bubble led to a much stronger and more persistent CCV and thus lower aerodynamic effectiveness of squealer tip for the transonic stage.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139171087","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 exhaust of internal combustion engines (ICEs) is characterized by rapid large amplitude exhaust gas temperature (EGT) pulsations that demand high-bandwidth measurements for accurate instantaneous and mean EGTs. While measurement technique challenges constrain on-engine EGT pulse measurements, reduced-order system simulations numerically estimate the EGT pulse and its mean to overcome the measurement limitation. Notwithstanding high-bandwidth pressure measurements, model calibration and validation for the EGT are confined to mean indications using sheathed thermal sensors like thermocouples and resistance thermometers. These EGT measurements are susceptible to errors caused by heat transfer, flow unsteadiness, and the thermal inertia of the sensor. Exposed thin-wire thermocouples provide an intermediate solution to the robustness-to-response tradeoff of thermal sensors. While the thermocouples' thermal inertia significantly affects the measured EGT pulse, the signal derivative (un-scaled dynamic error) provides greater insight by indicating the EGT waveform. This study utilizes a 50.8~$mu$m Type-K thermocouple to contrast the exhaust pressure and EGT pulses through the measured signal and its derivative. Experiments in a single-pipe exhaust of a heavy-duty diesel engine with isolated engine speed and load sweeps present significant differences between the pressure and indicative EGT waveforms. It also highlights a rapid pre-pulse fluctuation unique to the EGT pulse waveform caused by exhaust gas-dynamics and impacted by heat transfer. The study motivates the need for increased bandwidth EGT measurements to improve model validation of EGT pulse estimates while showcasing the utility of thin-wire thermocouples.
{"title":"Analyzing Engine Exhaust Gas Temperature Pulsations and Gas-Dynamics Using Thin-Wire Thermocouples","authors":"Varun Venkataraman, Beichuan Hong, A. Cronhjort","doi":"10.1115/1.4064314","DOIUrl":"https://doi.org/10.1115/1.4064314","url":null,"abstract":"The exhaust of internal combustion engines (ICEs) is characterized by rapid large amplitude exhaust gas temperature (EGT) pulsations that demand high-bandwidth measurements for accurate instantaneous and mean EGTs. While measurement technique challenges constrain on-engine EGT pulse measurements, reduced-order system simulations numerically estimate the EGT pulse and its mean to overcome the measurement limitation. Notwithstanding high-bandwidth pressure measurements, model calibration and validation for the EGT are confined to mean indications using sheathed thermal sensors like thermocouples and resistance thermometers. These EGT measurements are susceptible to errors caused by heat transfer, flow unsteadiness, and the thermal inertia of the sensor. Exposed thin-wire thermocouples provide an intermediate solution to the robustness-to-response tradeoff of thermal sensors. While the thermocouples' thermal inertia significantly affects the measured EGT pulse, the signal derivative (un-scaled dynamic error) provides greater insight by indicating the EGT waveform. This study utilizes a 50.8~$mu$m Type-K thermocouple to contrast the exhaust pressure and EGT pulses through the measured signal and its derivative. Experiments in a single-pipe exhaust of a heavy-duty diesel engine with isolated engine speed and load sweeps present significant differences between the pressure and indicative EGT waveforms. It also highlights a rapid pre-pulse fluctuation unique to the EGT pulse waveform caused by exhaust gas-dynamics and impacted by heat transfer. The study motivates the need for increased bandwidth EGT measurements to improve model validation of EGT pulse estimates while showcasing the utility of thin-wire thermocouples.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139168936","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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