The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
Alberto Talamo - One of the best experts on this subject based on the ideXlab platform.
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criticality assessment for prismatic high temperature Reactors by fuel stochastic monte carlo modeling
Annals of Nuclear Energy, 2008Co-Authors: Jitka žakova, Alberto TalamoAbstract:Modeling of prismatic high temperature Reactors requires a high precision description due to the triple heterogeneity of the core and also to the random distribution of fuel particles inside the fuel pins. On the latter issue, even with the most advanced Monte Carlo techniques, some approximation often arises while assessing the criticality level: first, a regular lattice of TRISO particles inside the fuel pins and, second, the cutting of TRISO particles by the fuel boundaries. We utilized two of the most accurate Monte Codes: MONK and MCNP, which are both used for licensing nuclear power plants in United Kingdom and in the USA, respectively, to evaluate the influence of the two previous approximations on estimating the criticality level of the Gas Turbine Modular Helium Reactor. The two codes exactly shared the same geometry and nuclear data library, ENDF/B, and only modeled different lattices of TRISO particles inside the fuel pins. More precisely, we investigated the difference between a regular lattice that cuts TRISO particles and a random lattice that axially repeats a region containing over 3000 non-cut particles. We have found that both Monte Carlo codes provide similar excesses of reactivity, provided that they share the same approximations.
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incineration of light water Reactor waste in high temperature gas Reactors axial fuel management and efficiency of americium and curium transmutation
Nuclear Science and Engineering, 2007Co-Authors: Alberto Talamo, Waclaw GudowskiAbstract:In the present study we investigate the influence of the fuel axial shuffling and the operational control rod maneuvering on the performances of the one-pass (no reprocessing) deep-burn incineration of light water Reactor waste in the gas turbine-Modular Helium Reactor. After an irradiation period, the fuel axial shuffling schedule has to take into account the fuel depletion profile generated by the adjustments of the position of the operational control rods, because the insertion of the rods strongly alters the neutron flux shape. We aimed at implementing a numerical simulation as close as possible to a real scenario and therefore took advantage of the powerful geometrical modeling capability of the MCB code to describe the Reactor in a detailed three-dimensional geometry model in which we simulated over 120 different burnable materials, each of them undergoing a different neutron flux intensity. We adjusted the position of the control rods every 90 effective full-power days of irradiation to maintain the core as close as possible to the critical condition; thereafter, we recalculated the neutron flux and cross sections by a new MCNP/ MCB run. At the present time, this sophisticated approach can be realized only by a computer cluster often 64-bit processors working in parallel mode. The fuel axial shuffling adds from 3 to 5% to the transmutation rates of 239 Pu, plutonium, and all actinides, which range from 80 to 86, 50 to 53, and 46 to 48%, respectively; the present results are 5 to 14% less compared to the case of a two-pass (reprocessing) deep burn. The efficiency of transmuting minor actinides has been estimated by comparing the long-term radio-toxicity of the fresh and irradiated americium and curium fuel; this comparison revealed that it is not worthwhile to transmute americium and curium in the current design of the gas turbine-Modular Helium Reactor by a one-pass deep burn.
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studies on the feasibility of the lwrs waste thorium in core fuel cycle in the gas turbine Modular Helium Reactor
Journal of Nuclear Science and Technology, 2006Co-Authors: Alberto TalamoAbstract:The capability to operate on LWRs waste constitutes one of the major benefits of the Gas Turbine-Modular Helium Reactor; in this paper, it has been evaluated the possibility to incinerate the LWRs waste and to simultaneously breed fissile 233U by fertile thorium. Since a mixture of pure 239Pu-thorium has shown a quite poor neutron economy, the LWRs waste-thorium fuel performance has been also tested when plutonium and thorium are allocated in different TRISO particles. More precisely, when fissile and fertile actinides share the same TRISO kernel, the resonance at 0.29 eV of the fission and capture microscopic cross sections of 239Pu diminishes also the absorption rate of fertile 232Th and thus it degrades the breeding process. Consequently, in the present studies, two different types of fuel have been utilized: the Driver Fuel, made of LWRs waste, and the Transmutation Fuel, made of fertile thorium. Since, in the thermal neutron energy range, the microscopic capture cross section of 232Th is about 80-100...
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comparison of mcb and monteburns monte carlo burnup codes on a one pass deep burn
Annals of Nuclear Energy, 2006Co-Authors: Alberto Talamo, Jerzy Cetnar, Wei Ji, Waclaw GudowskiAbstract:Numerical applications implemented on the Monte Carlo method have developed in line with the increase of computer power; nowadays, in the field of nuclear Reactor physics, it is possible to perform burnup simulations in a detailed 3D geometry and a continuous energy description by the Monte Carlo method; moreover, the required computing time can be abundantly reduced by taking advantage of a computer cluster. In this paper we focused on comparing the results of the two major Monte Carlo burnup codes, MONTEBURNS and MCB, when they share the same MCNP geometry, nuclear data library, core thermal power, and they apply the same refueling and shuffling schedule. While simulating a total operation time of the Gas Turbine-Modular Helium Reactor of 2100 effective full power days and a one-pass deep burn in-core fuel management schedule, we have found that the two Monte Carlo codes produce very similar results both on the criticality value of the core and the transmutation of the key actinides.
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comparison of mcb and monteburns monte carlo burnup codes on a one pass deep burn
Annals of Nuclear Energy, 2006Co-Authors: Alberto Talamo, Jerzy Cetnar, Waclaw GudowskiAbstract:Numerical applications implemented on the Monte Carlo method have developed in line with the increase of computer power; nowadays, in the field of nuclear Reactor physics, it is possible to perform burnup simulations in a detailed 3D geometry and a continuous energy description by the Monte Carlo method; moreover, the required computing time can be abundantly reduced by taking advantage of a computer cluster. In this paper we focused on comparing the results of the two major Monte Carlo burnup codes, MONTEBURNS and MCB, when they share the same MCNP geometry, nuclear data library, core thermal power, and they apply the same refueling and shuffling schedule. While simulating a total operation time of the Gas Turbine-Modular Helium Reactor of 2100 effective full power days and a one-pass deep burn in-core fuel management schedule, we have found that the two Monte Carlo codes produce very similar results both on the criticality value of the core and the transmutation of the key actinides.
Waclaw Gudowski - One of the best experts on this subject based on the ideXlab platform.
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incineration of light water Reactor waste in high temperature gas Reactors axial fuel management and efficiency of americium and curium transmutation
Nuclear Science and Engineering, 2007Co-Authors: Alberto Talamo, Waclaw GudowskiAbstract:In the present study we investigate the influence of the fuel axial shuffling and the operational control rod maneuvering on the performances of the one-pass (no reprocessing) deep-burn incineration of light water Reactor waste in the gas turbine-Modular Helium Reactor. After an irradiation period, the fuel axial shuffling schedule has to take into account the fuel depletion profile generated by the adjustments of the position of the operational control rods, because the insertion of the rods strongly alters the neutron flux shape. We aimed at implementing a numerical simulation as close as possible to a real scenario and therefore took advantage of the powerful geometrical modeling capability of the MCB code to describe the Reactor in a detailed three-dimensional geometry model in which we simulated over 120 different burnable materials, each of them undergoing a different neutron flux intensity. We adjusted the position of the control rods every 90 effective full-power days of irradiation to maintain the core as close as possible to the critical condition; thereafter, we recalculated the neutron flux and cross sections by a new MCNP/ MCB run. At the present time, this sophisticated approach can be realized only by a computer cluster often 64-bit processors working in parallel mode. The fuel axial shuffling adds from 3 to 5% to the transmutation rates of 239 Pu, plutonium, and all actinides, which range from 80 to 86, 50 to 53, and 46 to 48%, respectively; the present results are 5 to 14% less compared to the case of a two-pass (reprocessing) deep burn. The efficiency of transmuting minor actinides has been estimated by comparing the long-term radio-toxicity of the fresh and irradiated americium and curium fuel; this comparison revealed that it is not worthwhile to transmute americium and curium in the current design of the gas turbine-Modular Helium Reactor by a one-pass deep burn.
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comparison of mcb and monteburns monte carlo burnup codes on a one pass deep burn
Annals of Nuclear Energy, 2006Co-Authors: Alberto Talamo, Jerzy Cetnar, Wei Ji, Waclaw GudowskiAbstract:Numerical applications implemented on the Monte Carlo method have developed in line with the increase of computer power; nowadays, in the field of nuclear Reactor physics, it is possible to perform burnup simulations in a detailed 3D geometry and a continuous energy description by the Monte Carlo method; moreover, the required computing time can be abundantly reduced by taking advantage of a computer cluster. In this paper we focused on comparing the results of the two major Monte Carlo burnup codes, MONTEBURNS and MCB, when they share the same MCNP geometry, nuclear data library, core thermal power, and they apply the same refueling and shuffling schedule. While simulating a total operation time of the Gas Turbine-Modular Helium Reactor of 2100 effective full power days and a one-pass deep burn in-core fuel management schedule, we have found that the two Monte Carlo codes produce very similar results both on the criticality value of the core and the transmutation of the key actinides.
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comparison of mcb and monteburns monte carlo burnup codes on a one pass deep burn
Annals of Nuclear Energy, 2006Co-Authors: Alberto Talamo, Jerzy Cetnar, Waclaw GudowskiAbstract:Numerical applications implemented on the Monte Carlo method have developed in line with the increase of computer power; nowadays, in the field of nuclear Reactor physics, it is possible to perform burnup simulations in a detailed 3D geometry and a continuous energy description by the Monte Carlo method; moreover, the required computing time can be abundantly reduced by taking advantage of a computer cluster. In this paper we focused on comparing the results of the two major Monte Carlo burnup codes, MONTEBURNS and MCB, when they share the same MCNP geometry, nuclear data library, core thermal power, and they apply the same refueling and shuffling schedule. While simulating a total operation time of the Gas Turbine-Modular Helium Reactor of 2100 effective full power days and a one-pass deep burn in-core fuel management schedule, we have found that the two Monte Carlo codes produce very similar results both on the criticality value of the core and the transmutation of the key actinides.
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a deep burn fuel management strategy for the incineration of military plutonium in the gas turbine Modular Helium Reactor modeled in a detailed three dimensional geometry by the monte carlo continuous energy burnup code
Nuclear Science and Engineering, 2006Co-Authors: Alberto Talamo, Waclaw GudowskiAbstract:In the future development of nuclear energy, the graphite-moderated Helium-cooled Reactors may play an important role because of their valuable technical advantages: passive safety, low cost, flexibility in the choice of fuel, high conversion energy efficiency, high burnup, more resistant fuel cladding, and low power density. General Atomics possesses a long experience with this type of Reactor, and it has recently developed the gas turbine-Modular Helium Reactor (GT-MHR), a design where the nuclear power plant is structured into four Reactor modules of 600 MW(thermal). Amid its benefits, the GT-MHR offers a rather large flexibility in the choice of fuel type; Th, U, and Pu may be used in the manufacture of fuel with some degrees of freedom. As a consequence, the fuel management may be designed for different objectives aside from energy production, e.g., the reduction of actinide waste production through a fuel based on thorium. In our previous studies we analyzed the behavior of the GT-MHR with a plutonium fuel based on light water Reactor (LWR) waste; in the present study we focused on the incineration of military Pu. This choice of fuel requires a detailed numerical modeling of the Reactor since a high value of keff at the beginning of the Reactor operation requires the modeling both of control rods and of burnable poison; by contrast, when the GT-MHR is fueled with LWR waste, at the equilibrium of the fuel composition, the reactivity swing is small.
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comparative studies of jendl 3 3 jendl 3 2 jeff 3 jef 2 2 and endf b 6 8 data libraries on the monte carlo continuous energy modeling of the gas turbine Modular Helium Reactor operating with thorium fuels
Journal of Nuclear Science and Technology, 2005Co-Authors: Alberto Talamo, Waclaw GudowskiAbstract:One of the major benefits of the Gas Turbine-Modular Helium Reactor is the capability to operate with several different types of fuel; either Light Water Reactors waste, military plutonium or tho ...
Mortaza Yari - One of the best experts on this subject based on the ideXlab platform.
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exergoeconomic evaluation and optimization of a novel combined augmented kalina cycle gas turbine Modular Helium Reactor
Applied Thermal Engineering, 2016Co-Authors: S M S Mahmoudi, A Pourreza, A D Akbari, Mortaza YariAbstract:Abstract A new combined system including Gas Turbine-Modular Helium Reactor (GT-MHR) and an augmented Kalina cycle (AKC) is proposed, analyzed and optimized thermodynamically and economically. The simulation is performed using the conservation of energy, exergy balance and cost equations for each system component. For comparison purposes the previously published data for the combined cycle consisting of the GT-MHR and a conventional Kalina cycle (GT-MHR/KCS34), are also presented. Parametric studies are carried out to show the influences on exergy efficiency and total product unit cost of such decision parameters as compressor pressure ratio, pump pressure ratio, ammonia concentrations at different state points and separator temperature. The results indicate that the maximum exergy efficiency of the proposed system is 8.7% and 0.64% higher compared to the corresponding values for the GT-MHR and GT-MHR/KCS34, respectively. The results also show that the minimum total product unit cost for GT-MHR/AKC is 11.3% and 2.53% lower than the corresponding values for the GT-MHR and GT-MHR/KCS34, respectively. It is observed that, under optimized condition, the Helium mass flow rate in GT-MHR is reduced as the system is combined with the AKC. This is significant in reducing the size of system and consequently having more economically efficient system.
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a comparative exergoeconomic analysis of waste heat recovery from a gas turbine Modular Helium Reactor via organic rankine cycles
Sustainability, 2014Co-Authors: Naser Shokati, S M S Mahmoudi, Mortaza Yari, Farzad Mohammadkhani, Marc A RosenAbstract:A comparative exergoeconomic analysis is reported for waste heat recovery from a gas turbine-Modular Helium Reactor (GT-MHR) using various configurations of organic Rankine cycles (ORCs) for generating electricity. The ORC configurations studied are: a simple organic Rankine cycle (SORC), an ORC with an internal heat exchanger (HORC) and a regenerative organic Rankine cycle (RORC). Exergoeconomic analyses are performed with the specific exergy costing (SPECO) method. First, energy and exergy analyses are applied to the combined cycles. Then, a cost-balance, as well as auxiliary equations are developed for the components to determine the exergoeconomic parameters for the combined cycles and their components. The three combined cycles are compared considering the same operating conditions for the GT-MHR cycle, and a parametric study is done to reveal the effects on the exergoeconomic performance of the combined cycles of various significant parameters, e.g., turbine inlet and evaporator temperatures and compressor pressure ratio. The results show that the GT-MHR/RORC has the lowest unit cost of electricity generated by the ORC turbine. This value is highest for the GT-MHR/HORC. Furthermore, the GT-MHR/RORC has the highest and the GT-MHR/HORC has the lowest exergy destruction cost rate.
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exergoeconomic assessment and parametric study of a gas turbine Modular Helium Reactor combined with two organic rankine cycles
Energy, 2014Co-Authors: Farzad Mohammadkhani, S M S Mahmoudi, Mortaza Yari, Naser Shokati, Marc A RosenAbstract:An exergoeconomic analysis is reported for a combined system with a net electrical output of 299 MW in which waste heat from a Gas Turbine-Modular Helium Reactor (GT-MHR) is utilized by two Organic Rankine Cycles (ORCs). A parametric study is also done to reveal the effects on the exergoeconomic performance of the combined system of such significant parameters as compressor pressure ratio, turbine inlet temperature, temperatures of evaporators, pinch point temperature difference in the evaporators and degree of superheat at the ORC (Organic Rankine Cycle) turbines inlet. Finally the combined cycle performance is optimized from the viewpoint of exergoeconomics. The results show that the precooler, the intercooler and the ORC condensers exhibit the worst exergoeconomic performance. For the overall system, the exergoeconomic factor, the capital cost rate and the exergy destruction cost rate are determined to be 37.95%, 6876 $/h and 11,242 $/h, respectively. Also, it is observed that the unit cost of electricity produced by the GT-MHR turbine increases with increasing GT-MHR turbine inlet temperature but decreases as the other above mentioned parameters increase.
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an exergoeconomic investigation of waste heat recovery from the gas turbine Modular Helium Reactor gt mhr employing an ammonia water power cooling cycle
Energy, 2013Co-Authors: V Zare, S M S Mahmoudi, Mortaza YariAbstract:A detailed exergoeconomic analysis is performed for a combined cycle in which the waste heat from the Gas Turbine-Modular Helium Reactor (GT-MHR) is recovered by an ammonia–water power/cooling cogeneration system. Parametric investigations are conducted to evaluate the effects of decision variables on the performances of the GT-MHR and combined cycles. The performances of these cycles are then optimized from the viewpoints of first law, second law and exergoeconomics. It is found that, combining the GT-MHR with ammonia–water cycle not only enhances the first and second law efficiencies of the GT-MHR, but also it improves the cycle performance from the exergoeconomic perspective. The results show that, when the optimization is based on the exergoeconomics, the unit cost of products is reduced by 5.4% in combining the two mentioned cycles. This is achieved with a just about 1% increase in total investment cost rate since the Helium mass flow in the combined cycle is lower than that in the GT-MHR alone.
Haci Mehmet şahin - One of the best experts on this subject based on the ideXlab platform.
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investigation of a gas turbine Modular Helium Reactor using Reactor grade plutonium with 232th and 238u
Progress in Nuclear Energy, 2016Co-Authors: Sumer şahin, Ozgur Erol, Haci Mehmet şahinAbstract:Abstract Utilization of natural uranium (nat-U) and thorium as fertile fuels has been investigated by in a Gas Turbine – Modular Helium Reactor (GTMHR) using Reactor grade plutonium as driver fuel. A neutronic analysis for the full core Reactor was performed by using MCNP5 with ENDF/B-VI cross-section library. Different mixture ratios were tested in order to find the appropriate mixture ratio of fertile and fissile fuel particles that gives a comparable k eff value of the reference uranium fuel. Time dependent calculations were performed by using MONTEBURN2.0 with ORIGEN2.2 for each selected mixture. Different parameters (operation time, burnup value, fissile isotope change, etc.) were subject of performance comparison. The operation time and burnup values were close to each other with nat-U and thorium, namely 3205 days and 176 GWd/MTU for the former and 3175 days 181 GWd/MTU for the latter fertile fuel. In addition, the fissile isotope amount changed from initially 6940.1 kg–4579.2 kg at the end of its operation time for nat-U. These values were obtained for thorium as 6603.3 kg–4250.2 kg, respectively.
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weapons grade plutonium utilization with fertile materials in a gas turbine Modular Helium Reactor
Annals of Nuclear Energy, 2015Co-Authors: Ozgur Erol, Haci Mehmet şahinAbstract:Abstract In this study, neutronic performances of the fertile thorium and natural uranium were studied in a Gas Turbine-Modular Helium Reactor using Weapons Grade Plutonium as fissile fuel. In the first step of the calculation procedure, a series of neutronic calculations were made in order to find the proper mixture ratios for these fertile fuel mixtures by using MCNP5 with ENDF/B-VI cross-section library. After the determination of these mixture ratios, in order to compare these fuel mixtures, time dependent neutronic calculations were made by using Monteburns 2.0 with MCNP5 and Origen 2.2. According to the results obtained, different parameters (operation time, burnup value, fissile isotope production, etc.) were compared. Results of the first step showed that, in order to reach the reference k eff value, 690.6 kg more fissile isotope was used in natural uranium mixture than the thorium mixture. In the second step of this study, time dependent calculations showed that for the natural uranium mixture, operation time and burnup values were found as 1935 days and 177.76 GWd/MTU, respectively, while these values for thorium mixture were 1925 days and 153.95 GWd/MTU.
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alternative operating conditions for the Modular Helium Reactor
Energy Conversion and Management, 2012Co-Authors: Haci Mehmet şahin, Omur AkbayirAbstract:Abstract In this study, alternative operating conditions for the Modular Helium Reactor (MHR) were investigated to increase coolant outlet temperature above 850 °C, while keeping the peak fuel temperature below acceptable level at normal operation. Parametric thermal–hydraulic simulations were carried out by using Computational Fluid Dynamics software ANSYS 13.0 CFD FLUENT. The simulated geometry was chosen as an Equivalent Cylinder Model. The porous media approach has been applied to model the complex structure in the core. The study began with an analysis of the current 600 MWt GT-MHR (Gas Turbine-Modular Helium Reactor). The numerical model was validated by other studies. Then, three alternative operating conditions were simulated: (1) with a coolant inlet temperature of 491 °C, a coolant flow rate of 226 kg/s, (2) with a coolant inlet temperature of 641 °C, a coolant flow rate of 320 kg/s, (3) with a coolant inlet temperature of 590 °C, a coolant flow rate of 320 kg/s. The results show that a MHR with these alternative operating conditions have a coolant outlet temperatures about 1000 °C.
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utilization of thorium in a gas turbine Modular Helium Reactor
Energy Conversion and Management, 2012Co-Authors: Haci Mehmet şahin, Ozgur Erol, Adem AcirAbstract:Abstract Gas Turbine-Modular Helium Reactor (GT-MHR) is one of the new types of the Reactors with high efficiency and increased safety features. The usage of different kinds of fissile material in this Reactor can increase the life of it. Weapons-grade plutonium (WGrPu), which can be acquired from the old dismantled nuclear weapons, can be an option in a GT-MHR. In order to increase the sustainability of the WGrPu resources this fuel can be mixed with thorium, which is a fertile material that can be found in the nature and has resources three times more than uranium. In this study, possibility of utilization of the weapons-grade plutonium–thorium mixture was investigated and an optimum mixture ratio was determined. The behavior of this mixture and the original fuel was studied by using MCNP5 1.4, Monteburns 2.0 and Origen 2.2 tools. Calculations showed that, a GT-MHR type Reactor, which is using the original TRISO fuel particle mixture of 20% enriched uranium + natural uranium (original fuel) has an effective multiplication factor (keff) of 1.270. Corresponding to this keff value the weapons grade plutonium/thorium oxide mixture was found 19%/81%. By using Monteburns Code, the operation time, which describes the time passed until the Reactor reaches a keff value of 1.02, was found as 515 days for the original fuel and 1175 days for the weapons grade plutonium mixture. Furthermore, the burn-up values for the original fuel and WGrPu fuels were found as 47.69 and 119.27 GWd/MTU, respectively.
S M S Mahmoudi - One of the best experts on this subject based on the ideXlab platform.
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exergoeconomic evaluation and optimization of a novel combined augmented kalina cycle gas turbine Modular Helium Reactor
Applied Thermal Engineering, 2016Co-Authors: S M S Mahmoudi, A Pourreza, A D Akbari, Mortaza YariAbstract:Abstract A new combined system including Gas Turbine-Modular Helium Reactor (GT-MHR) and an augmented Kalina cycle (AKC) is proposed, analyzed and optimized thermodynamically and economically. The simulation is performed using the conservation of energy, exergy balance and cost equations for each system component. For comparison purposes the previously published data for the combined cycle consisting of the GT-MHR and a conventional Kalina cycle (GT-MHR/KCS34), are also presented. Parametric studies are carried out to show the influences on exergy efficiency and total product unit cost of such decision parameters as compressor pressure ratio, pump pressure ratio, ammonia concentrations at different state points and separator temperature. The results indicate that the maximum exergy efficiency of the proposed system is 8.7% and 0.64% higher compared to the corresponding values for the GT-MHR and GT-MHR/KCS34, respectively. The results also show that the minimum total product unit cost for GT-MHR/AKC is 11.3% and 2.53% lower than the corresponding values for the GT-MHR and GT-MHR/KCS34, respectively. It is observed that, under optimized condition, the Helium mass flow rate in GT-MHR is reduced as the system is combined with the AKC. This is significant in reducing the size of system and consequently having more economically efficient system.
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a thermodynamic comparison between organic rankine and kalina cycles for waste heat recovery from the gas turbine Modular Helium Reactor
Energy, 2015Co-Authors: V Zare, S M S MahmoudiAbstract:A comparative thermodynamic analysis and optimization is presented for waste heat recovery from the Gas Turbine-Modular Helium Reactor (GT-MHR) employing organic Rankine cycle (ORC) and Kalina cycle (KC). Thermodynamic models are developed for the stand alone GT-MHR and the two proposed combined cycles and the effects on the performances of the cycles are investigated of decision variables. The cycles' performances are then optimized based on the first and second law of thermodynamics. The results showed that, employing ORC is more appropriate than KC for GT-MHR waste heat recovery. The first and second law efficiencies of the combined GT-MHR/ORC are higher than those of the combined GT-MHR/KC. In addition, the Helium mass flow rate in the combined GT-MHR/ORC is significantly lower than that in the combined GT-MHR/KC. Moreover, the high-pressure level of the ORC is extremely lower than that of the KC under optimized conditions. Furthermore, the superheated vapor at the ORC turbine exit avoids droplet erosion and allows for reliable operation while the stream exiting the KC turbine is a two-phase flow.
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a comparative exergoeconomic analysis of waste heat recovery from a gas turbine Modular Helium Reactor via organic rankine cycles
Sustainability, 2014Co-Authors: Naser Shokati, S M S Mahmoudi, Mortaza Yari, Farzad Mohammadkhani, Marc A RosenAbstract:A comparative exergoeconomic analysis is reported for waste heat recovery from a gas turbine-Modular Helium Reactor (GT-MHR) using various configurations of organic Rankine cycles (ORCs) for generating electricity. The ORC configurations studied are: a simple organic Rankine cycle (SORC), an ORC with an internal heat exchanger (HORC) and a regenerative organic Rankine cycle (RORC). Exergoeconomic analyses are performed with the specific exergy costing (SPECO) method. First, energy and exergy analyses are applied to the combined cycles. Then, a cost-balance, as well as auxiliary equations are developed for the components to determine the exergoeconomic parameters for the combined cycles and their components. The three combined cycles are compared considering the same operating conditions for the GT-MHR cycle, and a parametric study is done to reveal the effects on the exergoeconomic performance of the combined cycles of various significant parameters, e.g., turbine inlet and evaporator temperatures and compressor pressure ratio. The results show that the GT-MHR/RORC has the lowest unit cost of electricity generated by the ORC turbine. This value is highest for the GT-MHR/HORC. Furthermore, the GT-MHR/RORC has the highest and the GT-MHR/HORC has the lowest exergy destruction cost rate.
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exergoeconomic assessment and parametric study of a gas turbine Modular Helium Reactor combined with two organic rankine cycles
Energy, 2014Co-Authors: Farzad Mohammadkhani, S M S Mahmoudi, Mortaza Yari, Naser Shokati, Marc A RosenAbstract:An exergoeconomic analysis is reported for a combined system with a net electrical output of 299 MW in which waste heat from a Gas Turbine-Modular Helium Reactor (GT-MHR) is utilized by two Organic Rankine Cycles (ORCs). A parametric study is also done to reveal the effects on the exergoeconomic performance of the combined system of such significant parameters as compressor pressure ratio, turbine inlet temperature, temperatures of evaporators, pinch point temperature difference in the evaporators and degree of superheat at the ORC (Organic Rankine Cycle) turbines inlet. Finally the combined cycle performance is optimized from the viewpoint of exergoeconomics. The results show that the precooler, the intercooler and the ORC condensers exhibit the worst exergoeconomic performance. For the overall system, the exergoeconomic factor, the capital cost rate and the exergy destruction cost rate are determined to be 37.95%, 6876 $/h and 11,242 $/h, respectively. Also, it is observed that the unit cost of electricity produced by the GT-MHR turbine increases with increasing GT-MHR turbine inlet temperature but decreases as the other above mentioned parameters increase.
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an exergoeconomic investigation of waste heat recovery from the gas turbine Modular Helium Reactor gt mhr employing an ammonia water power cooling cycle
Energy, 2013Co-Authors: V Zare, S M S Mahmoudi, Mortaza YariAbstract:A detailed exergoeconomic analysis is performed for a combined cycle in which the waste heat from the Gas Turbine-Modular Helium Reactor (GT-MHR) is recovered by an ammonia–water power/cooling cogeneration system. Parametric investigations are conducted to evaluate the effects of decision variables on the performances of the GT-MHR and combined cycles. The performances of these cycles are then optimized from the viewpoints of first law, second law and exergoeconomics. It is found that, combining the GT-MHR with ammonia–water cycle not only enhances the first and second law efficiencies of the GT-MHR, but also it improves the cycle performance from the exergoeconomic perspective. The results show that, when the optimization is based on the exergoeconomics, the unit cost of products is reduced by 5.4% in combining the two mentioned cycles. This is achieved with a just about 1% increase in total investment cost rate since the Helium mass flow in the combined cycle is lower than that in the GT-MHR alone.