The Experts below are selected from a list of 171 Experts worldwide ranked by ideXlab platform
Kandadai Srinivasan - One of the best experts on this subject based on the ideXlab platform.
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A trade-off between maxima in efficiency and specific work output of super- and trans-critical CO2 Brayton Cycles
Journal of Supercritical Fluids, 2015Co-Authors: Pardeep Garg, Pramod Kumar, Kandadai SrinivasanAbstract:Several operational aspects for thermal power plants in general are non-intuitive and involve simultaneous optimization of a number of operational parameters. In the case of solar operated power plants, it is even more difficult due to varying heat source temperatures induced by variability in insolation levels. This paper introduces a quantitative methodology for load regulation of a CO2 based Brayton Cycle power plant using the `thermal efficiency and specific work output' coordinate system. The analysis shows that a transcritical CO2 Cycle offers more flexibility under part load performance than the Supercritical Cycle in case of non-solar power plants. However, for concentrated solar power, where efficiency is important, Supercritical CO2 Cycle fares better than transcritical CO2 Cycle. A number of empirical equations relating heat source temperature, high side pressure with efficiency and specific work output are proposed which could assist in generating control algorithms. (C) 2015 Elsevier B.V. All rights reserved.
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Supercritical carbon dioxide brayton Cycle for concentrated solar power
Journal of Supercritical Fluids, 2013Co-Authors: Pardeep Garg, Pramod Kumar, Kandadai SrinivasanAbstract:Supercritical carbon dioxide based Brayton Cycle for possible concentrated solar power applications is investigated and compared with trans- and sub-critical operations of the same fluid. Thermal efficiency, specific work output and magnitude of irreversibility generation are used as some of the performance indicators. While the thermal efficiency increases almost linearly with low side pressure in the sub- and trans-critical Cycles, it attains a maximum in the Supercritical regime at 85 bar after which there are diminishing returns on increasing the low side pressure. It is also found that Supercritical Cycle is capable of producing power with a thermal efficiency of >30% even at a lower source temperature (820K) and accounting for foreseeable non-idealities albeit with a higher turbine inlet pressure (similar to 300 bar) which is not matched by a conventional sub-critical Cycle even with a high source temperature of 978K. The reasons for lower efficiency than in an ideal Cycle are extracted from an irreversibility analysis of components, namely, compressor, regenerator, turbine and gas cooler. Low sensitivity to the source temperature and extremely small volumetric flow rates in the Supercritical Cycle could offset the drawback of high pressures through a compact system.
Burhanuddin Halimi - One of the best experts on this subject based on the ideXlab platform.
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computational analysis of Supercritical co2 brayton Cycle power conversion system for fusion reactor
Energy Conversion and Management, 2012Co-Authors: Burhanuddin HalimiAbstract:Abstract The Optimized Supercritical Cycle Analysis (OSCA) code is being developed to analyze the design of a Supercritical carbon dioxide (S-CO2) driven Brayton Cycle for a fusion reactor as part of the Modular Optimal Balance Integral System (MOBIS). This system is based on a recompression Brayton Cycle. S-CO2 is adopted as the working fluid for MOBIS because of its easy availability, high density and low chemical reactivity. The reheating concept is introduced to enhance the Cycle thermal efficiency. The helium-cooled lithium lead model AB of DEMO fusion reactor is used as reference in this paper.
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Quick Design Method for Lead Cooled Battery Fast Reactor BORIS
ASME 2011 Small Modular Reactors Symposium, 2011Co-Authors: Burhanuddin HalimiAbstract:This paper focuses on developing design methodologies that can quickly generate pre-conceptual design of battery reactor by means of first principle calculations, starting from core region to reactor vessel assembly and power conversion system. First, given the core composition and weight fraction data, the MCNP code is run to generate a neutron flux spectrum for homogenized geometry that is used with the available cross section data to generate the single group constants for neutron diffusion calculation. The bucklings of the critical core found from Neutronics Optimized Reactor Analysis (NORA) based on the diffusion equation are then compared against those obtained by trial and error utilizing the MCNP code over the range of design variables to generate a linear relationship used to adjust the buckling computed by the neutron diffusion equation. Next, key design parameters and constraints are chosen for the reactor vessel assembly considering technical specifications such as the thermal limits and manufacturing difficulties. Two objective functions are picked based on thermohydrodynamic and economic grounds. A first principle system code Optimized Supercritical Cycle Analysis (OSCA) is run to generate boundary conditions at heat exchanger interface with a view to optimizing the design of the Supercritical fluid driven Brayton Cycle. Selected design parameters are made available to the Momentum Integral Numerical Analysis (MINA) code to evaluate steady-state mass flow rate and coolant temperature distribution of the reactor vessel assembly. They are compared against the prescribed engineering constraints. The steps are repeated until an optimum value is obtained. The proposed methodology may help reduce the amount of computational effort required in initial stages of small reactor design. The resulting geometric information can be used as a starting point for detailed design procedure.Copyright © 2011 by ASME
Pramod Kumar - One of the best experts on this subject based on the ideXlab platform.
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Supercritical Carbon Dioxide-Based Power Cycles
Encyclopedia of Sustainable Technologies, 2020Co-Authors: Pradip Dutta, Pramod KumarAbstract:Thermal-based energy resources including fossil fuels as well as renewable sources such as solar and biomass involve a wide range of heat source temperatures. Effective utilization of all these resources demands judicious choice of thermodynamic Cycles to convert the heat into electric power. In this context, Supercritical carbon dioxide (S-CO 2 ) working in a closed Brayton Cycle loop is found to be suitable for temperatures normally realized from concentrating solar as well as biomass combustion. The present study discusses the work reported in literature on the thermodynamic performance of some basic variants of the CO 2 Cycle, such as the subcritical, transcritical, and the Supercritical Cycle. Comparative thermodynamic analysis of the Cycles shows that S-CO 2 is the best performer, and it has the potential to replace steam in conventional thermal power plants, solar thermal, as well as nuclear plants. The major advantages of S-CO 2 Brayton Cycle over steam Rankine Cycle are discussed. Some technological challenges for ultimate scale-up and commercialization are identified, in the form of development of critical components and subsystems.
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A trade-off between maxima in efficiency and specific work output of super- and trans-critical CO2 Brayton Cycles
Journal of Supercritical Fluids, 2015Co-Authors: Pardeep Garg, Pramod Kumar, Kandadai SrinivasanAbstract:Several operational aspects for thermal power plants in general are non-intuitive and involve simultaneous optimization of a number of operational parameters. In the case of solar operated power plants, it is even more difficult due to varying heat source temperatures induced by variability in insolation levels. This paper introduces a quantitative methodology for load regulation of a CO2 based Brayton Cycle power plant using the `thermal efficiency and specific work output' coordinate system. The analysis shows that a transcritical CO2 Cycle offers more flexibility under part load performance than the Supercritical Cycle in case of non-solar power plants. However, for concentrated solar power, where efficiency is important, Supercritical CO2 Cycle fares better than transcritical CO2 Cycle. A number of empirical equations relating heat source temperature, high side pressure with efficiency and specific work output are proposed which could assist in generating control algorithms. (C) 2015 Elsevier B.V. All rights reserved.
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Supercritical carbon dioxide brayton Cycle for concentrated solar power
Journal of Supercritical Fluids, 2013Co-Authors: Pardeep Garg, Pramod Kumar, Kandadai SrinivasanAbstract:Supercritical carbon dioxide based Brayton Cycle for possible concentrated solar power applications is investigated and compared with trans- and sub-critical operations of the same fluid. Thermal efficiency, specific work output and magnitude of irreversibility generation are used as some of the performance indicators. While the thermal efficiency increases almost linearly with low side pressure in the sub- and trans-critical Cycles, it attains a maximum in the Supercritical regime at 85 bar after which there are diminishing returns on increasing the low side pressure. It is also found that Supercritical Cycle is capable of producing power with a thermal efficiency of >30% even at a lower source temperature (820K) and accounting for foreseeable non-idealities albeit with a higher turbine inlet pressure (similar to 300 bar) which is not matched by a conventional sub-critical Cycle even with a high source temperature of 978K. The reasons for lower efficiency than in an ideal Cycle are extracted from an irreversibility analysis of components, namely, compressor, regenerator, turbine and gas cooler. Low sensitivity to the source temperature and extremely small volumetric flow rates in the Supercritical Cycle could offset the drawback of high pressures through a compact system.
Pardeep Garg - One of the best experts on this subject based on the ideXlab platform.
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A trade-off between maxima in efficiency and specific work output of super- and trans-critical CO2 Brayton Cycles
Journal of Supercritical Fluids, 2015Co-Authors: Pardeep Garg, Pramod Kumar, Kandadai SrinivasanAbstract:Several operational aspects for thermal power plants in general are non-intuitive and involve simultaneous optimization of a number of operational parameters. In the case of solar operated power plants, it is even more difficult due to varying heat source temperatures induced by variability in insolation levels. This paper introduces a quantitative methodology for load regulation of a CO2 based Brayton Cycle power plant using the `thermal efficiency and specific work output' coordinate system. The analysis shows that a transcritical CO2 Cycle offers more flexibility under part load performance than the Supercritical Cycle in case of non-solar power plants. However, for concentrated solar power, where efficiency is important, Supercritical CO2 Cycle fares better than transcritical CO2 Cycle. A number of empirical equations relating heat source temperature, high side pressure with efficiency and specific work output are proposed which could assist in generating control algorithms. (C) 2015 Elsevier B.V. All rights reserved.
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Supercritical carbon dioxide brayton Cycle for concentrated solar power
Journal of Supercritical Fluids, 2013Co-Authors: Pardeep Garg, Pramod Kumar, Kandadai SrinivasanAbstract:Supercritical carbon dioxide based Brayton Cycle for possible concentrated solar power applications is investigated and compared with trans- and sub-critical operations of the same fluid. Thermal efficiency, specific work output and magnitude of irreversibility generation are used as some of the performance indicators. While the thermal efficiency increases almost linearly with low side pressure in the sub- and trans-critical Cycles, it attains a maximum in the Supercritical regime at 85 bar after which there are diminishing returns on increasing the low side pressure. It is also found that Supercritical Cycle is capable of producing power with a thermal efficiency of >30% even at a lower source temperature (820K) and accounting for foreseeable non-idealities albeit with a higher turbine inlet pressure (similar to 300 bar) which is not matched by a conventional sub-critical Cycle even with a high source temperature of 978K. The reasons for lower efficiency than in an ideal Cycle are extracted from an irreversibility analysis of components, namely, compressor, regenerator, turbine and gas cooler. Low sensitivity to the source temperature and extremely small volumetric flow rates in the Supercritical Cycle could offset the drawback of high pressures through a compact system.
Paul Colonna - One of the best experts on this subject based on the ideXlab platform.
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Method for the Preliminary Fluid Dynamic Design of High-Temperature Mini-Organic Rankine Cycle Turbines
Journal of Engineering for Gas Turbines and Power, 2017Co-Authors: Sebastian Bahamonde, Matteo Pini, Carlo De Servi, Antonio Rubino, Paul ColonnaAbstract:Copyright © 2017 by ASME. Widespread adoption of renewable energy technologies will arguably benefit from the availability of economically viable distributed thermal power conversion systems. For this reason, considerable efforts have been dedicated in recent years to R & D over mini-organic Rankine Cycle (ORC) power plants, thus with a power capacity approximately in the 3-50 kW range. The application of these systems for waste heat recovery from diesel engines of long-haul trucks stands out because of the possibility of achieving economy of production. Many technical challenges need to be solved, as the system must be sufficiently efficient, light, and compact. The design paradigm is therefore completely different from that of conventional stationary ORC power plants of much larger capacity. A high speed turbine is arguably the expander of choice, if high conversion efficiency is targeted, thus high maximum Cycle temperature. Given the lack of knowledge on the design of these turbines, which depends on a large number of constraints, a novel optimal design method integrating the preliminary design of the thermodynamic Cycle and that of the turbine has been developed. The method is applicable to radial inflow, axial and radial outflow turbines, and to superheated and Supercritical Cycle configurations. After a limited number of working fluids are selected, the feasible design space is explored by means of thermodynamic Cycle design calculations integrated with a simplified turbine design procedure, whereby the isentropic expansion efficiency is prescribed. Starting from the resulting design space, optimal preliminary designs are obtained by combining Cycle calculations with a 1D mean-line code, subject to constraints. The application of the procedure is illustrated for a test case: the design of turbines to be tested in a new experimental setup named organic rankine Cycle hybrid integrated device (ORCHID) which is being constructed at the Delft University of Technology, Delft, The Netherlands. The first turbine selected for further design and construction employs siloxane MM (hexamethyldisiloxane, C 6 H 18 OSi 2 ), Supercritical Cycle, and the radial inflow configuration. The main preliminary design specifications are power output equal to 11.6 kW, turbine inlet temperature equal to 300°C, maximum Cycle pressure equal to 19.9 bar, expansion ratio equal to 72, rotational speed equal to 90 krpm, inlet diameter equal to 75 mm, minimum blade height equal to 2 mm, degree of reaction equal to 0.44, and estimated total-to-static efficiency equal to 77.3%. Results of the design calculations are affected by considerable uncertainty related to the loss correlations employed for the preliminary turbine design, as they have not been validated yet for this highly unconventional supersonic and transonic mini turbine. Future work will be dedicated to the extension of the method to encompass the preliminary design of heat exchangers and the off-design operation of the system.