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Zhen Huang - One of the best experts on this subject based on the ideXlab platform.
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Fuel Design and management for the control of advanced compression ignition combustion modes
Progress in Energy and Combustion Science, 2011Co-Authors: Xingcai Lu, Zhen HuangAbstract:Abstract Due to concerns regarding the greenhouse effect and limitations on carbon dioxide emissions, the possibility of a next-generation combustion mode for internal combustion engines that can simultaneously reduce exhaust emissions and substantially improve thermal efficiency has drawn increasing attention. The most prominent characteristic of new combustion modes, such as Homogenous-Charge Compression-Ignition (HCCI), Stratified-Charge Compression-Ignition (SCCI), and Low-Temperature Combustion (LTC), is the requirement of creating a homogenous mixture or controllable stratified mixture prior to ignition. To this end, a lean Fuel/air mixture and/or a controllable high level of exhaust gas recirculation (EGR) are employed to prolong the timescale of the ignition chemistry and port Fuel injection or early in-cylinder injection is used to lengthen the mixing period. The mixture then undergoes controlled self-ignition near the top dead center (TDC) position due to the compression effect of the piston’s upward movement. It is worth noting that the entire combustion process lacks a direct method for the control of ignition timing and combustion rate, which are instead controlled primarily by chemical kinetics and, to a lesser extent, by turbulence and mixing. Because of the significant impacts of Fuel physical–chemical properties on the ignition and combustion process, Fuel Design and management has become the most common approach for the control of ignition timing and combustion rate in such advanced combustion modes. This paper summarizes the concepts and methods of Fuel Design and management and provides an overview of the effects of these strategies on ignition, combustion, and emissions for HCCI, LTC, and SCCI engines, respectively. From part 2 to part 4, the paper focuses on the effect of Fuel Design on HCCI combustion. A Fuel index suitable for describing ignition characteristic under HCCI operating conditions is first introduced. Next, the proposed Fuel Design concept is described, including principles and main methodologies. Strategies based on the Fuel Design concept (including Fuel additives, Fuel blending, and dual-Fuel technology) are discussed for primary reference Fuels (PRF), alternative Fuels, and practical gasoline and diesel Fuels. Additionally, the effects of real-time Fuel Design on HCCI combustion Fueled with PRFs and dimethyl ether/liquefied petroleum gas (DME–LPG) are evaluated. Diesel HCCI combustion has suffered from difficulties in homogenous mixture formation and an excessively high combustion rate. Therefore, LTC, which concentrates on local combustion temperature and a balance of mixture formation timescale and ignition timescale, has been proposed by many researchers. In Part 5, this paper provides an overview of the major points and research progress of LTC, with a preliminary discussion of the fundamental importance of Fuel properties and Fuel Design strategy on the LTC process and emissions. Due to the stratification strategy has the capable of extending the HCCI operation range to higher loads, SCCI combustion, which incorporates HCCI combustion into a traditional combustion mode, has the potential to be used in commercial engines. Thus, this paper discusses the principles and control strategies of Fuel Design and management and also summarizes recent progress and future trends. The effect of Fuel Design and management on SCCI combustion is assessed for high cetane number Fuels and high octane number Fuels as well as the in SCCI combustion of gasoline–diesel dual-Fuel and blends.
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improving the combustion and emissions of direct injection compression ignition engines using oxygenated Fuel additives combined with a cetane number improver
Energy & Fuels, 2005Co-Authors: Xingcai Lu, Jianguang Yang, And Wugao Zhang, Zhen HuangAbstract:According to the Fuel Design concept, three oxygenated Fuels including ethanol, dimethyl carbonate (DMC), and dimethoxy methane (DMM) were selected to mix with diesel Fuel. Then, the effects of oxygen content and the cetane number of the blend Fuels on diesel engine combustion and emissions were evaluated. The experiments were conducted on a four-cylinder high-speed diesel engine. The results show that, with the increase of the oxygen content in blend Fuels, the ignition timing delays and the combustion duration shorten at different operating conditions, and the brake thermal efficiency improves from middle to full loads. The engine NOx emissions decreased at overall operating ranges when oxygenated Fuels were added to the diesel Fuel, and smoke emissions also improved for all oxygenated blend Fuels except for ethanol−diesel blends at low and middle loads. In the case of the DMC−diesel blend Fuel, when the oxygen content increased up to 15%, the smoke number decreased by 75%, and NOx emission improved by ...
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a fundamental study on the control of the hcci combustion and emissions by Fuel Design concept combined with controllable egr part 1 the basic characteristics of hcci combustion
Fuel, 2005Co-Authors: Xingcai Lu, Wei Chen, Zhen HuangAbstract:This article investigates the basic combustion parameters including start of the ignition timing, burn duration, cycle-to-cycle variation, and carbon monoxide (CO), unburned hydrocarbon (UHC), and nitric oxide (NOx) emissions of homogeneous charge compression ignition (HCCI) engines Fueled with primary reference Fuels (PRFs) and their mixtures. Two primary reference Fuels, n-heptane and iso-octane, and their blends with RON25, RON50, RON75, and RON90 were evaluated. The experimental results show that, in the first-stage combustion, the start of ignition retards, the maximum heat release rate decreases, and the pressure rising and the temperature rising during the first-stage combustion decrease with the increase of the research octane number (RON). Furthermore, the cumulative heat release in the first-stage combustion is strongly dependent on the concentration of n-heptane in the mixture. The start of ignition of the second-stage combustion is linear with the start of ignition of the first-stage. The combustion duration of the second-stage combustion decreases with the increase of the equivalence ration and the decrease of the octane number. The cycle-to-cycle variation improved with the decrease of the octane number.
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a fundamental study on the control of the hcci combustion and emissions by Fuel Design concept combined with controllable egr part 2 effect of operating conditions and egr on hcci combustion
Fuel, 2005Co-Authors: Xingcai Lu, Wei Chen, Zhen HuangAbstract:In Part 1, the effects of octane number of primary reference Fuels and equivalence ration on combustion characteristics of a single-cylinder HCCI engine were studied. In this part, the influence of exhaust gas recirculation (EGR) rate, intake charge temperature, coolant temperature, and engine speed on the HCCI combustion characteristics and its emissions were evaluated. The experimental results indicate that the ignition timing of the first-stage combustion and second-stage combustion retard, and the combustion duration prolongs with the introduction of cooled EGR. At the same time, the HCCI combustion using high cetane number Fuels can tolerate with a higher EGR rate, but only 45% EGR rate for RON75 at 1800 rpm. Furthermore, there is a moderate effect of EGR rate on CO and UHC emissions for HCCI combustion engines Fueled with n-heptane and RON25, but a distinct effect on emissions for higher octane number Fuels. Moreover, the combustion phase advances, and the combustion duration shorten with the increase of intake charge temperature and the coolant out temperature, and the decrease of the engine speed. At last, it can be found that the intake charge temperature gives the most sensitive influence on the HCCI combustion characteristics.
Germina Ilas - One of the best experts on this subject based on the ideXlab platform.
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AUTOMATED Fuel Design OPTIMIZATION FOR HIGH FLUX ISOTOPE REACTOR LOW ENRICHED URANIUM CORE Design
'EDP Sciences', 2021Co-Authors: J. W. Bae, David Chandler, Benjamin R Betzler, Germina IlasAbstract:The low enriched uranium (LEU) conversion project for the High Flux Isotope Reactor (HFIR) requires that the converted core Design perform as well as or better than the current high enriched uranium core Design with respect to key performance metrics, such as isotope production, while maintaining sufficient safety margins. Various Designs and Fuel shapes have been explored in previous optimization studies. A suite of scripts has been developed for HFIR LEU Design and analysis to simplify the reactor physics and thermal hydraulics (TH) analyses. The scripts include generating a high-fidelity 3D HFIR model to perform core depletion simulations with the SHIFT Monte Carlo code, performing an essential rod criticality search during depletion, parsing SHIFT output to determine HFIR key metrics, and performing TH analysis with the HFIR Steady-State Heat Transfer Code. Previously, these scripts were separated and required human interaction between simulation stages. These scripts have been modernized and integrated into a single Python package (the Python HFIR Analysis and Measurement Engine or PHAME) to streamline execution and avoid potential human error. After modernizing the suite of scripts into a single, automated workflow, the tool set was wrapped into an in-house metaheuristic optimization driver that enables different optimization methods, such as simulated annealing and particle swarm. The optimization driver samples a Fuel shape, runs PHAME, calculates the cost function with the metrics returned from PHAME, and repeats those steps until it finds an optimal Fuel shape. This work demonstrates the workflow of a comprehensive, automated reactor Design study and how metaheuristic optimization methods can be leveraged to fine-tune a Design parameter like Fuel shape. This workflow of wrapping an optimization driver on a full-scale reactor analysis suite increases Design and analysis efficiency
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neutronic and thermal hydraulic feasibility studies for high flux isotope reactor conversion to low enriched uranium silicide dispersion Fuel
Annals of Nuclear Energy, 2019Co-Authors: David Chandler, Germina Ilas, Benjamin R Betzler, David Howard Cook, David G RenfroAbstract:Abstract An iterative Design process involving neutronic and thermal-hydraulic modeling and simulation has been employed to assess the feasibility of converting the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) silicide dispersion Fuel. ORNL is funded by the National Nuclear Security Administration to evaluate HFIR conversion. Previous HFIR conversion studies focused on U-10Mo monolithic Fuel; however, due to potential fabrication issues with the complex HFIR U-10Mo Fuel Design, ORNL is evaluating U3Si2-Al dispersion Fuel as an alternative LEU Fuel system. Fueled by 10.1 kg of HEU and operated at 85 MW, HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world. Retrofitting a compact, high-power density, HEU-based core with LEU is a challenging problem to solve, especially when considering the conversion requirements. Neutronic and thermal-hydraulic analyses were performed with Shift and HSSHTC, respectively, to predict reactor performance and thermal safety margins. A number of Designs were proposed and evaluated using an iterative approach in an effort to show that reactor performance could match that obtained using HEU Fuel and that thermal safety margins were adequate. This study concludes that conversion of HFIR with U3Si2-Al LEU Fuel is feasible if, among other requirements, the Fuel meat region is centered and symmetric about the Fuel plate thickness centerline, the active Fuel zone length is increased from 50.80 cm to 55.88 cm, the proposed fabrication tolerances can be met, and the Fuel can be qualified for HFIR conditions.
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high fidelity modeling and simulation for a high flux isotope reactor low enriched uranium core Design
Nuclear Science and Engineering, 2017Co-Authors: Benjamin R Betzler, David Chandler, Eva E Davidson, Germina IlasAbstract:A high-fidelity model of the High Flux Isotope Reactor (HFIR) with a low-enriched uranium (LEU) Fuel Design and a representative experiment loading has been developed to serve as a new reference mo...
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preliminary evaluation of alternate Designs for hfir low enriched uranium Fuel
2014Co-Authors: David G Renfro, Germina Ilas, David Chandler, David Howard Cook, Prashant K Jain, Jennifer R ValentineAbstract:Engineering Design studies of the feasibility of conversion of the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) Fuel are ongoing at Oak Ridge National Laboratory (ORNL) as part of an effort sponsored by the U.S. Department of Energy’s Global Threat Reduction Initiative (GTRI)/Reduced Enrichment for Research and Test Reactors (RERTR) program. The Fuel type selected by the program for the conversion of the five high-power research reactors in the U.S. that still use HEU Fuel is a new U-Mo monolithic Fuel. Studies by ORNL have previously indicated that HFIR can be successfully converted using the new Fuel provided (1) the reactor power can be increased from 85 MW to 100 MW and (2) the Fuel can be fabricated to a specific reference Design. Fabrication techniques for the new Fuel are under development by the program but are still immature, especially for the “complex” aspects of the HFIR Fuel Design. In FY 2012, the program underwent a major shift in focus to emphasize developing and qualifying processes for the fabrication of reliable and affordable LEU Fuel. In support of this new focus and in an effort to ensure that the HFIR Fuel Design is asmore » suitable for reliable fabrication as possible, ORNL undertook the present study to propose and evaluate several alternative Design features. These features include (1) eliminating the Fuel zone axial contouring in the previous reference Design by substituting a permanent neutron absorber in the lower unFueled region of all of the Fuel plates, (2) relocating the burnable neutron absorber from the Fuel plates of the inner Fuel element to the side plates of the inner Fuel element (the Fuel plates of the outer Fuel element do not contain a burnable absorber), (3) relocating the Fuel zone inside the Fuel plate to be centered on the centerline of the depth of the plate, and (4) reshaping the radial contour of the relocated Fuel zone to be symmetric about this centerline. The present studies used current analytical tools to evaluate the various alternate Designs for cycle length, scientific performance (e.g., neutron scattering), and steady-state and transient thermal performance using both safety limit and nominal parameter assumptions. The studies concluded that a new reference Design combining a permanent absorber in the lower unFueled region of all of the Fuel plates, a burnable absorber in the inner element side plates, and a relocated and reshaped (but still radially contoured) Fuel zone will allow successful conversion of HFIR. Future collaboration with the program will reveal whether the new reference Design can be fabricated reliably and affordably. Following this feedback, additional studies using state-of-the-art developmental analytical tools are proposed to optimize the Design of the Fuel zone radial contour and the amount and location of both types of neutron absorbers to further flatten thermal peaks while maximizing the performance of the reactor.« less
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low enriched uranium Fuel Design with two dimensional grading for the high flux isotope reactor
2011Co-Authors: Germina Ilas, Trent PrimmAbstract:An engineering Design study of the conversion of the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) Fuel is ongoing at Oak Ridge National Laboratory. The computational models developed during fiscal year 2010 to search for an LEU Fuel Design that would meet the requirements for the conversion and the results obtained with these models are documented and discussed in this report. Estimates of relevant reactor performance parameters for the LEU Fuel core are presented and compared with the corresponding data for the currently operating HEU Fuel core. The results obtained indicate that the LEU Fuel Design would maintain the current performance of the HFIR with respect to the neutron flux to the central target region, reflector, and beam tube locations under the assumption that the operating power for the reactor Fueled with LEU can be increased from the current value of 85 MW to 100 MW.
E Shwageraus - One of the best experts on this subject based on the ideXlab platform.
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advanced gas cooled reactors technology for enabling molten salt reactors Design estimation of coolant impact on neutronic performance
Progress in Nuclear Energy, 2020Co-Authors: M Margulis, E ShwagerausAbstract:Abstract It has been shown that the Fluoride Salt-Cooled High-Temperature Reactors (FHR) can benefit from adopting some features of well-established Advanced Gas-cooled Reactors (AGR) technology pioneered in the United Kingdom. AGRs offer a number of technological advantages that can potentially speed up the development of FHRs, such as experience with operation at high temperatures, graphite moderated core, Fuel Design, on-line reFuelling, and experience in manufacturing and construction of large concrete pressure vessels with steel liners. This paper summarises relevant information available in the open literature on AGR core operation and Design, focusing on neutronic characteristics. The obtained information was used to test the capabilities of Monte Carlo code Serpent to reproduce Fuel temperature coefficient of a typical AGR. Then, the paper presents a neutronic analysis of the impact of CO2 coolant substitution with molten salt (FLiBe). The results obtained from the analysis showed that Serpent accurately reproduces the value and behaviour of Fuel temperature coefficient both for fresh and depleted Fuel conditions. However, subsequent sensitivity and uncertainty analysis showed high uncertainties in the calculated Fuel temperature coefficients. The change of the coolant results in significant variation of an AGR neutronic characteristics. The analysis suggests that the use of FLiBe salt as a coolant in AGR-type reactors introduces additional Design challenges related to the uncertainties in nuclear data. This work summarises an initial stage of AGRESR project, which was aiming to review the AGR technology relevant to FHR development.
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thermal hydraulic Design methodology and trade off studies for a dual salt breed and burn molten salt reactor
Nuclear Engineering and Design, 2020Co-Authors: Alisha Kasam, Jeongik Lee, E ShwagerausAbstract:Abstract A methodology is developed for thermal-hydraulic analysis and Design of a breed-and-burn molten salt reactor (BBMSR). By using separate Fuel and coolant molten salts, the BBMSR is proposed to overcome key materials limitations of traditional breed-and-burn and molten salt reactor Designs. The BBMSR Fuel concept includes an inner wall that divides the ascending and descending flows of naturally convecting Fuel salt. A finite-difference model (FDM) is developed to iteratively solve for the temperature and velocity distributions in both sections of the concentric Fuel. The FDM is used to perform parametric studies of the effect of Fuel geometry and heat generation rate on the heat transfer performance of the Fuel. The FDM is then integrated into a Design search algorithm that identifies the operational limits for a given BBMSR Fuel geometry, within a set of defined constraints. A range of thermal-hydraulic Fuel Design options are evaluated, and trade-off studies are performed to identify the most promising Fuel Design space for competitive power production and neutronic efficiency in the BBMSR.
Xingcai Lu - One of the best experts on this subject based on the ideXlab platform.
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Fuel Design and management for the control of advanced compression ignition combustion modes
Progress in Energy and Combustion Science, 2011Co-Authors: Xingcai Lu, Zhen HuangAbstract:Abstract Due to concerns regarding the greenhouse effect and limitations on carbon dioxide emissions, the possibility of a next-generation combustion mode for internal combustion engines that can simultaneously reduce exhaust emissions and substantially improve thermal efficiency has drawn increasing attention. The most prominent characteristic of new combustion modes, such as Homogenous-Charge Compression-Ignition (HCCI), Stratified-Charge Compression-Ignition (SCCI), and Low-Temperature Combustion (LTC), is the requirement of creating a homogenous mixture or controllable stratified mixture prior to ignition. To this end, a lean Fuel/air mixture and/or a controllable high level of exhaust gas recirculation (EGR) are employed to prolong the timescale of the ignition chemistry and port Fuel injection or early in-cylinder injection is used to lengthen the mixing period. The mixture then undergoes controlled self-ignition near the top dead center (TDC) position due to the compression effect of the piston’s upward movement. It is worth noting that the entire combustion process lacks a direct method for the control of ignition timing and combustion rate, which are instead controlled primarily by chemical kinetics and, to a lesser extent, by turbulence and mixing. Because of the significant impacts of Fuel physical–chemical properties on the ignition and combustion process, Fuel Design and management has become the most common approach for the control of ignition timing and combustion rate in such advanced combustion modes. This paper summarizes the concepts and methods of Fuel Design and management and provides an overview of the effects of these strategies on ignition, combustion, and emissions for HCCI, LTC, and SCCI engines, respectively. From part 2 to part 4, the paper focuses on the effect of Fuel Design on HCCI combustion. A Fuel index suitable for describing ignition characteristic under HCCI operating conditions is first introduced. Next, the proposed Fuel Design concept is described, including principles and main methodologies. Strategies based on the Fuel Design concept (including Fuel additives, Fuel blending, and dual-Fuel technology) are discussed for primary reference Fuels (PRF), alternative Fuels, and practical gasoline and diesel Fuels. Additionally, the effects of real-time Fuel Design on HCCI combustion Fueled with PRFs and dimethyl ether/liquefied petroleum gas (DME–LPG) are evaluated. Diesel HCCI combustion has suffered from difficulties in homogenous mixture formation and an excessively high combustion rate. Therefore, LTC, which concentrates on local combustion temperature and a balance of mixture formation timescale and ignition timescale, has been proposed by many researchers. In Part 5, this paper provides an overview of the major points and research progress of LTC, with a preliminary discussion of the fundamental importance of Fuel properties and Fuel Design strategy on the LTC process and emissions. Due to the stratification strategy has the capable of extending the HCCI operation range to higher loads, SCCI combustion, which incorporates HCCI combustion into a traditional combustion mode, has the potential to be used in commercial engines. Thus, this paper discusses the principles and control strategies of Fuel Design and management and also summarizes recent progress and future trends. The effect of Fuel Design and management on SCCI combustion is assessed for high cetane number Fuels and high octane number Fuels as well as the in SCCI combustion of gasoline–diesel dual-Fuel and blends.
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improving the combustion and emissions of direct injection compression ignition engines using oxygenated Fuel additives combined with a cetane number improver
Energy & Fuels, 2005Co-Authors: Xingcai Lu, Jianguang Yang, And Wugao Zhang, Zhen HuangAbstract:According to the Fuel Design concept, three oxygenated Fuels including ethanol, dimethyl carbonate (DMC), and dimethoxy methane (DMM) were selected to mix with diesel Fuel. Then, the effects of oxygen content and the cetane number of the blend Fuels on diesel engine combustion and emissions were evaluated. The experiments were conducted on a four-cylinder high-speed diesel engine. The results show that, with the increase of the oxygen content in blend Fuels, the ignition timing delays and the combustion duration shorten at different operating conditions, and the brake thermal efficiency improves from middle to full loads. The engine NOx emissions decreased at overall operating ranges when oxygenated Fuels were added to the diesel Fuel, and smoke emissions also improved for all oxygenated blend Fuels except for ethanol−diesel blends at low and middle loads. In the case of the DMC−diesel blend Fuel, when the oxygen content increased up to 15%, the smoke number decreased by 75%, and NOx emission improved by ...
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a fundamental study on the control of the hcci combustion and emissions by Fuel Design concept combined with controllable egr part 1 the basic characteristics of hcci combustion
Fuel, 2005Co-Authors: Xingcai Lu, Wei Chen, Zhen HuangAbstract:This article investigates the basic combustion parameters including start of the ignition timing, burn duration, cycle-to-cycle variation, and carbon monoxide (CO), unburned hydrocarbon (UHC), and nitric oxide (NOx) emissions of homogeneous charge compression ignition (HCCI) engines Fueled with primary reference Fuels (PRFs) and their mixtures. Two primary reference Fuels, n-heptane and iso-octane, and their blends with RON25, RON50, RON75, and RON90 were evaluated. The experimental results show that, in the first-stage combustion, the start of ignition retards, the maximum heat release rate decreases, and the pressure rising and the temperature rising during the first-stage combustion decrease with the increase of the research octane number (RON). Furthermore, the cumulative heat release in the first-stage combustion is strongly dependent on the concentration of n-heptane in the mixture. The start of ignition of the second-stage combustion is linear with the start of ignition of the first-stage. The combustion duration of the second-stage combustion decreases with the increase of the equivalence ration and the decrease of the octane number. The cycle-to-cycle variation improved with the decrease of the octane number.
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a fundamental study on the control of the hcci combustion and emissions by Fuel Design concept combined with controllable egr part 2 effect of operating conditions and egr on hcci combustion
Fuel, 2005Co-Authors: Xingcai Lu, Wei Chen, Zhen HuangAbstract:In Part 1, the effects of octane number of primary reference Fuels and equivalence ration on combustion characteristics of a single-cylinder HCCI engine were studied. In this part, the influence of exhaust gas recirculation (EGR) rate, intake charge temperature, coolant temperature, and engine speed on the HCCI combustion characteristics and its emissions were evaluated. The experimental results indicate that the ignition timing of the first-stage combustion and second-stage combustion retard, and the combustion duration prolongs with the introduction of cooled EGR. At the same time, the HCCI combustion using high cetane number Fuels can tolerate with a higher EGR rate, but only 45% EGR rate for RON75 at 1800 rpm. Furthermore, there is a moderate effect of EGR rate on CO and UHC emissions for HCCI combustion engines Fueled with n-heptane and RON25, but a distinct effect on emissions for higher octane number Fuels. Moreover, the combustion phase advances, and the combustion duration shorten with the increase of intake charge temperature and the coolant out temperature, and the decrease of the engine speed. At last, it can be found that the intake charge temperature gives the most sensitive influence on the HCCI combustion characteristics.
Shwageraus E - One of the best experts on this subject based on the ideXlab platform.
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Neutronic and thermal-hydraulic Fuel Design for a dual-salt breed-and-burn molten salt reactor
2021Co-Authors: Kasam A, Shwageraus EAbstract:© 2020 A breed-and-burn molten salt reactor (BBMSR) concept is proposed to achieve high uranium utilisation in a once-through Fuel cycle. By using separate Fuel and coolant molten salts, the BBMSR may overcome key materials limitations of traditional breed-and-burn (B&B) and molten salt reactor Designs. A central challenge in Design of the BBMSR Fuel is balancing the neutronic requirements for B&B operation with thermal-hydraulic requirements for safe and economically competitive reactor operation. Fuel configurations that satisfy both neutronic and thermal-hydraulic objectives were identified for 5% enriched and 20% enriched uranium feed Fuel. A neutron balance method and thermal-hydraulic Design algorithm were used to evaluate uranium utilisation and maximum allowable power density, respectively, for a range of configurations. B&B operation is achievable in the 5% enriched version with orders of magnitude greater uranium utilisation compared to light water reactors, but with moderately lower power density. Using 20% enriched feed Fuel relaxes neutronic constraints so a wider range of Fuel configurations can be considered, but there is a strong inverse correlation between power density and uranium utilisation. The Fuel Design study indicates the flexibility of the BBMSR concept to operate along a spectrum of modes ranging from high Fuel utilisation at moderate power density using 5% enriched uranium feed Fuel, to high power density and moderate utilisation using 20% uranium enrichment
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Thermal-hydraulic Design methodology and trade-off studies for a dual-salt breed-and-burn molten salt reactor
2020Co-Authors: Kasam A, Ji Lee, Shwageraus EAbstract:© 2019 Elsevier B.V. A methodology is developed for thermal-hydraulic analysis and Design of a breed-and-burn molten salt reactor (BBMSR). By using separate Fuel and coolant molten salts, the BBMSR is proposed to overcome key materials limitations of traditional breed-and-burn and molten salt reactor Designs. The BBMSR Fuel concept includes an inner wall that divides the ascending and descending flows of naturally convecting Fuel salt. A finite-difference model (FDM) is developed to iteratively solve for the temperature and velocity distributions in both sections of the concentric Fuel. The FDM is used to perform parametric studies of the effect of Fuel geometry and heat generation rate on the heat transfer performance of the Fuel. The FDM is then integrated into a Design search algorithm that identifies the operational limits for a given BBMSR Fuel geometry, within a set of defined constraints. A range of thermal-hydraulic Fuel Design options are evaluated, and trade-off studies are performed to identify the most promising Fuel Design space for competitive power production and neutronic efficiency in the BBMSR
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Advanced Gas-cooled reactors technology for enabling molten-salt reactors Design - Estimation of coolant impact on neutronic performance
2020Co-Authors: Margulis M, Shwageraus EAbstract:© 2020 Elsevier Ltd It has been shown that the Fluoride Salt-Cooled High-Temperature Reactors (FHR) can benefit from adopting some features of well-established Advanced Gas-cooled Reactors (AGR) technology pioneered in the United Kingdom. AGRs offer a number of technological advantages that can potentially speed up the development of FHRs, such as experience with operation at high temperatures, graphite moderated core, Fuel Design, on-line reFuelling, and experience in manufacturing and construction of large concrete pressure vessels with steel liners. This paper summarises relevant information available in the open literature on AGR core operation and Design, focusing on neutronic characteristics. The obtained information was used to test the capabilities of Monte Carlo code Serpent to reproduce Fuel temperature coefficient of a typical AGR. Then, the paper presents a neutronic analysis of the impact of CO2 coolant substitution with molten salt (FLiBe). The results obtained from the analysis showed that Serpent accurately reproduces the value and behaviour of Fuel temperature coefficient both for fresh and depleted Fuel conditions. However, subsequent sensitivity and uncertainty analysis showed high uncertainties in the calculated Fuel temperature coefficients. The change of the coolant results in significant variation of an AGR neutronic characteristics. The analysis suggests that the use of FLiBe salt as a coolant in AGR-type reactors introduces additional Design challenges related to the uncertainties in nuclear data. This work summarises an initial stage of AGRESR project, which was aiming to review the AGR technology relevant to FHR development
