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Fengrui Sun - One of the best experts on this subject based on the ideXlab platform.
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performance comparison of an endoreversible closed variable Temperature heat reservoir intercooled regenerated brayton cycle under maximum power and maximum power density conditions
International Journal of Sustainable Energy, 2011Co-Authors: Lingen Chen, Junhua Wang, Fengrui SunAbstract:In this paper, the power density, defined as the Ratio of power output to the maximum specific volume in the cycle, is taken as the objective for performance analysis of an endoreversible closed intercooled regenerated Brayton cycle coupled to variable-Temperature heat reservoirs from the viewpoint of finite-time thermodynamics (FTT) or entropy geneRation minimization. The analytical formulae for the relations between power density and pressure Ratio are derived with the heat resistance losses in the hot- and cold-side heat exchangers, the intercooler, and the regenerator. Some results in the recent FTT literature are replicated. The intercooling pressure Ratio is optimized for dimensionless power density. The effects of component (the intercooler, the regenerator, and the hot- and cold-side heat exchangers) effectivenesses, the thermal capacity rate of the working fluid, the heat reservoir inlet Temperature Ratio, and the inlet Temperature Ratio of the cooling fluid in the intercooler and the cold-side h...
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power density optimisation of an irreversible variable Temperature heat reservoir closed intercooled regenerated brayton cycle
International journal of ambient energy, 2009Co-Authors: Lingen Chen, Junhua Wang, Fengrui SunAbstract:SYNOPSIS In this paper, power density, defined as the Ratio of power output to maximum specific volume in the cycle, is analysed and optimised for an irreversible closed intercooled regenerated Brayton cycle coupled to variable-Temperature heat reservoirs, according to the theory of finite-time thermodynamics. The analytical formulae for dimensionless power density and efficiency, as functions of the total pressure Ratio, the inter-cooling pressure Ratio, the component (i.e. regenerator, intercooler, and hot- and cold-side heat exchangers) effectivenesses, the compressor and turbine efficiencies, the thermal capacity rates of the working fluid and the heat reservoirs, the pressure recovery coefficients, the heat reservoir inlet Temperature Ratio, and the inlet Temperature Ratio of cooling fluid in the intercooler and the cold-side heat reservoir, are derived. The optimum dimensionless power density is obtained by optimising the intercooling pressure Ratio. The maximum dimensionless power density is obtain...
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power density analysis and optimization of an irreversible closed intercooled regenerated brayton cycle
Mathematical and Computer Modelling, 2008Co-Authors: Junhua Wang, Fengrui SunAbstract:In this paper, power density, defined as the Ratio of power output to the maximum specific volume in the cycle, is optimized for an irreversible closed intercooled regenerated Brayton cycle coupled to constant-Temperature heat reservoirs in the viewpoint of the theory of thermodynamic optimization. The analytical formulae for dimensionless power density and efficiency, as functions of the total pressure Ratio, the intercooling pressure Ratio, the components (the regenerator, the intercooler, the hot- and cold-side heat exchangers) effectiveness, the compressor and turbine efficiencies, the heat reservoir Temperature Ratio, and the Temperature Ratio of the cooling fluid in the intercooler and the cold-side heat reservoir, are derived. The optimum dimensionless power density is obtained by optimizing the intercooling pressure Ratio. The maximum dimensionless power density is obtained by searching the optimum heat conductance distributions between the hot- and cold-side heat exchangers for a fixed total heat exchanger inventory and fixed heat conductance distributions of the regenerator and the intercooler, and by searching the optimum intercooling pressure Ratio. When the optimization is performed with respect to the total pressure Ratio of the cycle, the maximum dimensionless power density can be maximized again, and a double-maximum power density and the corresponding optimum total pressure Ratios are obtained. The effects of the heat reservoir Temperature Ratio, the Temperature Ratio of the cooling fluid in the intercooler and the cold-side heat reservoir, the efficiencies of the compressors and the turbine, and the total heat exchanger inventory on the optimum power density, the maximum power density, and the double-maximum power density and the corresponding optimal total pressure Ratio are analyzed by numerical examples. In the analysis, the heat resistance losses in the four heat exchangers, and the irreversible compression and expansion losses in the compressors and the turbine are taken into account.
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Power density optimisation of an endoreversible closed variable-Temperature heat reservoir intercooled regenerated Brayton cycle
International Journal of Ambient Energy, 2006Co-Authors: Junhua Wang, Fengrui SunAbstract:SYNOPSIS Taking power density, defined as the Ratio of power output to the maximum specific volume in the cycle, as the objective function, this paper applies the theory of finite time thermodynamics to find the optimal distribution of heat conductance of the hot- and cold-side heat exchangers, the optimal intercooling pressure Ratio, the optimal total pressure Ratio and the optimal heat capacity Ratio between working fluid and heat reservoir of an endoreversible closed intercooled regenerated Brayton cycle coupled to variable-Temperature heat reservoirs with heat resistance losses in the hot- and cold-side heat exchangers, the intercooler and the regenerator, by using detailed numerical calculation. The maximum power density, the double-maximum power density and the triple-maximum power density are obtained by optimisation. The effects of some design parameters, including the cycle inlet heat reservoir Temperature Ratio, the inlet Temperature Ratio of cooling fluid in the intercooler and the cold-side he...
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power and efficiency analysis of an endoreversible closed intercooled regenerated brayton cycle
International Journal of Exergy, 2004Co-Authors: Lingen Chen, Wenhua Wang, Fengrui SunAbstract:In this paper, finite-time thermodynamics (FTT) is applied to analyse the performance of an endoreversible closed intercooled regenerated Brayton cycle coupled with variable-Temperature heat reservoirs. The analytical formulae of dimensionless power and efficiency are thus derived. The intercooling pressure Ratio is optimised for maximum power and maximum efficiency, respectively. The effects of component (the intercooler, the regenerator and the hot- and cold-side heat exchangers) effectiveness; the thermal capacity rate of the working fluid; the heat reservoir inlet Temperature Ratio; the inlet Temperature Ratio of the cooling fluid in the intercooler and the cold-side heat reservoir on maximum power and its corresponding efficiency and corresponding intercooling pressure Ratio, as well as maximum efficiency and its corresponding power and corresponding intercooling pressure Ratio are analysed by detailed numerical examples. Some results in the recent FTT literature are replicated.
Wenhua Wang - One of the best experts on this subject based on the ideXlab platform.
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power and efficiency analysis of an endoreversible closed intercooled regenerated brayton cycle
International Journal of Exergy, 2004Co-Authors: Lingen Chen, Wenhua Wang, Fengrui SunAbstract:In this paper, finite-time thermodynamics (FTT) is applied to analyse the performance of an endoreversible closed intercooled regenerated Brayton cycle coupled with variable-Temperature heat reservoirs. The analytical formulae of dimensionless power and efficiency are thus derived. The intercooling pressure Ratio is optimised for maximum power and maximum efficiency, respectively. The effects of component (the intercooler, the regenerator and the hot- and cold-side heat exchangers) effectiveness; the thermal capacity rate of the working fluid; the heat reservoir inlet Temperature Ratio; the inlet Temperature Ratio of the cooling fluid in the intercooler and the cold-side heat reservoir on maximum power and its corresponding efficiency and corresponding intercooling pressure Ratio, as well as maximum efficiency and its corresponding power and corresponding intercooling pressure Ratio are analysed by detailed numerical examples. Some results in the recent FTT literature are replicated.
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closed intercooled regenerator brayton cycle with constant Temperature heat reservoirs
Applied Energy, 2004Co-Authors: Wenhua Wang, Fengrui SunAbstract:The performance of an irreversible closed intercooled regenerator Brayton-cycle coupled to constant-Temperature heat reservoirs is analyzed by using the theory of finite-time thermodynamics (FTT). Analytical formulae for dimensionless power and efficiency are derived. Especially, the intercooling pressure-Ratio is optimized for the optimal power and the optimal efficiency, respectively. The effects of component (the intercooler, the regenerator, and the hot- and cold-side heat-exchangers) effectivenesses, the compressor and turbine efficiencies, the heat-reservoir Temperature-Ratio, and the Temperature Ratio of the cooling fluid in the intercooler and the cold-side heat reservoir on the optimal power and the corresponding efficiency and corresponding intercooling pressure Ratio, as well as the optimal efficiency and the corresponding power and corresponding intercooling pressure-Ratio are analyzed by detailed numerical examples.
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the effect of heat transfer on the performance of an endoreversible closed intercooled regenerated brayton cycle
Journal of The Energy Institute, 2004Co-Authors: Wenhua Wang, Lingen Chen, Fengrui SunAbstract:Finite-time thermodynamics (FTT) is applied to analyze the performance of an endoreversible intercooled regenerated Brayton cycle coupled to constant-Temperature heat reservoirs. The analytical formulae of dimensionless power and efficiency of the cycle are derived. The intercooling pressure Ratio is optimized for dimensionless power and efficiency, respectively. The effects are analyzed, with use of detailed numerical examples, of the effectiveness of the intercooler, the regenerator, and the hot- and cold-side heat exchangers; of the Temperature Ratio of the cycle heat reservoirs and of the Temperature Ratio between heat sinks of the intercooler and the cold-side heat reservoir on the optimal dimensionless power output and its corresponding efficiency, the optimal efficiency and its corresponding dimensionless power output and the intercooling pressure Ratios, which correspond to the optimal dimensionless power output or the optimal efficiency of the cycle. When the effectiveness of the regenerator is zero and the Temperature Ratio of heat sink of the intercooler is equal to that of the cold-side heat reservoir, the intercooling process is not involved in the cycle and the heat transfers between the working fluid and the heat reservoirs can be carried out ideally. The results then replicate those given in the recent literature.
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performance analysis for an irreversible variable Temperature heat reservoir closed intercooled regenerated brayton cycle
Energy Conversion and Management, 2003Co-Authors: Wenhua Wang, Fengrui SunAbstract:In this paper, the theory of finite time thermodynamics is used in the performance analysis of an irreversible closed intercooled regenerated Brayton cycle coupled to variable Temperature heat reservoirs. The analytical formulae for dimensionless power and efficiency, as functions of the total pressure Ratio, the intercooling pressure Ratio, the component (regenerator, intercooler, hot and cold side heat exchangers) effectivenesses, the compressor and turbine efficiencies and the thermal capacity rates of the working fluid and the heat reservoirs, the pressure recovery coefficients, the heat reservoir inlet Temperature Ratio, and the cooling fluid in the intercooler and the cold side heat reservoir inlet Temperature Ratio, are derived. The intercooling pressure Ratio is optimized for optimal power and optimal efficiency, respectively. The effects of component (regenerator, intercooler and hot and cold side heat exchangers) effectivenesses, the compressor and turbine efficiencies, the pressure recovery coefficients, the heat reservoir inlet Temperature Ratio and the cooling fluid in the intercooler and the cold side heat reservoir inlet Temperature Ratio on optimal power and its corresponding intercooling pressure Ratio, as well as optimal efficiency and its corresponding intercooling pressure Ratio are analyzed by detailed numerical examples. When the heat transfers between the working fluid and the heat reservoirs are executed ideally, the pressure drop losses are small enough to be neglected and the thermal capacity rates of the heat reservoirs are infinite, the results of this paper replicate those obtained in recent literature.
W M Moslem - One of the best experts on this subject based on the ideXlab platform.
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nonlinear structures of the korteweg de vries and modified korteweg de vries equations in non maxwellian electron positron ion plasma solitons collision and rogue waves
Physics of Plasmas, 2014Co-Authors: S A Eltantawy, W M MoslemAbstract:Solitons (small-amplitude long-lived waves) collision and rogue waves (large-amplitude short-lived waves) in non-Maxwellian electron-positron-ion plasma have been investigated. For the solitons collision, the extended Poincare-Lighthill-Kuo perturbation method is used to derive the coupled Korteweg-de Vries (KdV) equations with the quadratic nonlinearities and their corresponding phase shifts. The calculations reveal that both positive and negative polarity solitons can propagate in the present model. At critical value of plasma parameters, the coefficients of the quadratic nonlinearities disappear. Therefore, the coupled modified KdV (mKdV) equations with cubic nonlinearities and their corresponding phase shifts have been derived. The effects of the electron-to-positron Temperature Ratio, the ion-to-electron Temperature Ratio, the positron-to-ion concentRation, and the nonextensive parameter on the colliding solitons profiles and their corresponding phase shifts are examined. Moreover, geneRation of ion-...
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on a plasma having nonextensive electrons and positrons rogue and solitary wave propagation
Physics of Plasmas, 2011Co-Authors: E I Elawady, W M MoslemAbstract:GeneRation of nonlinear ion-acoustic waves in a plasma having nonextensive electrons and positrons has been studied. Two wave modes existing in such plasma are considered, namely solitary and rogue waves. The reductive perturbation method is used to obtain a Korteweg-de Vries equation describing the system. The latter admits solitary wave pulses, while the dynamics of the modulationally unstable wave packets described by the Korteweg-de Vries equation gives rise to the formation of rogue excitation that is described by a nonlinear Schrodinger equation. The dependence of both solitary and rogue waves profiles on the nonextensive parameter, positron-to-ion concentRation Ratio, electron-to-positron Temperature Ratio, and ion-to-electron Temperature Ratio are investigated numerically. The results from this work are expected to contribute to the in-depth understanding of the nonlinear excitations that may appear in nonextensive astrophysical plasma environments, such as galactic clusters, interstellar medium, etc.
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zakharov kuznetsov burgers equation in superthermal electron positron ion plasma
Astrophysics and Space Science, 2011Co-Authors: N A Elbedwehy, W M MoslemAbstract:Properties of three-dimensional ion-acoustic soli- tary and shock waves accompining electron-positron-ion magnetoplasma with high-energy (superthermal) electrons and positrons are investigated. For this purpose, a Zakharov- Kuznetsov-Burgers (ZKB) equation is derived from the ion continuity equation, ion momentum equation with kinematic viscosity among ions fluid, electrons, and positrons having kappa distribution together with the Poisson equation. The dependence of the solitary and shock excitations character- istics on the parameter measuring the superthermality κ ,t he ion gyrofrequency � , the unperturbed positrons-to-ions den- sity Ratio ν, the viscosity parameter η, the direction cosine � , the ion-to-electron Temperature Ratio σi, and the electron-to- positron Temperature Ratio σp have been investigated. More- over, it is found that the parameters κ, � , ν, η, andlead to accelerate the particles, whereas the parameters σi and σp would lead to decelerate them. Numerical calculations re- veal that the nonlinear pulses polarity are always positive. This study could be useful to understand the nonlinear elec- trostatic excitations in interstellar medium.
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head on collision of ion acoustic solitary waves in a thomas fermi plasma containing degenerate electrons and positrons
Physics Letters A, 2009Co-Authors: E F Elshamy, W M Moslem, P K ShuklaAbstract:Abstract Head-on collision between two ion acoustic solitary waves in a Thomas–Fermi plasma containing degenerate electrons and positrons is investigated using the extended Poincare–Lighthill–Kuo (PLK) method. The results show that the phase shifts due to the collision are strongly dependent on the positron-to-electron number density Ratio, the electron-to-positron Fermi Temperature Ratio and the ion-to-electron Fermi Temperature Ratio. The present study might be helpful to understand the excitation of nonlinear ion-acoustic solitary waves in a degenerate plasma such as in superdense white dwarfs.
Guven Gonca - One of the best experts on this subject based on the ideXlab platform.
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performance analysis of a spark ignition si otto cycle oc gasoline engine under realistic power rp and realistic power density rpd conditions pages 475 486
Politeknik Dergisi, 2017Co-Authors: Guven GoncaAbstract:This study presents performance optimization of an Otto cycle (OC) gasoline engine using new criteria named as realistic power (RP) and realistic power density (RPD) conditions based on finite-time thermodynamics (FTT). The effects of design and operating parameters such as cycle Temperature Ratio, cycle pressure Ratio, friction coefficient, engine speed, mean piston speed, stroke length, inlet Temperature, inlet pressure, equivalence Ratio, compression Ratio and bore-stroke length Ratio on the performance parameters such as effective efficiency, effective power and power density have been examined. Moreover, the energy losses have been determined as fuel's energy and they have been illustrated based on incomplete combustion, friction, heat transfer and exhaust output by using figures. Realistic values of specific heats have been used depend on Temperature of working fluid. The results obtained demonstrated that the engine performance increases with increasing some parameters such as cycle Temperature Ratio, cycle pressure Ratio, inlet pressure; with decreasing some parameters such as friction coefficient, inlet Temperature. However, the engine performance could increase or decrease with respect to different conditions for some parameters such as engine speed, mean piston speed, stroke length, equivalence Ratio and compression Ratio. The results of this study could be used an engineering tool by Otto cycle engine designers.
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comparative performance analyses of irreversible omce otto miller cycle engine dimce diesel miller cycle engine dmce dual miller cycle engine
Energy, 2016Co-Authors: Guven GoncaAbstract:Abstract In this paper, comparative performance analyses of the irreversible OMCE (Otto Miller cycle engine), DiMCE (Diesel Miller cycle engine) and DMCE (Dual Miller cycle engine) based on the MP (maximum dimensionless power) output, MPD (maximum dimensionless power density) and MEF (maximum thermal efficiency) criteria have been performed by taking irreversibility due to irreversible-adiabatic compression and expansion processes into account. The maximum values of the thermal efficiency, dimensionless power output and dimensionless power density are obtained depending on pressure Ratio, stroke Ratio, cut-off Ratio, miller cycle Ratio, exhaust Temperature Ratio, cycle Temperature Ratio and cycle pressure Ratio and the isentropic efficiencies of irreversible-adiabatic processes. The engine design parameters at the MP, MPD and MEF conditions are determined and their variations are investigated with respect to miller cycle Ratio.
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the influences of the engine design and operating parameters on the performance of a turbocharged and steam injected diesel engine running with the miller cycle
Applied Mathematical Modelling, 2016Co-Authors: Guven GoncaAbstract:Abstract This study reports the influences of the engine design and operating parameters on the performance of a turbocharged, steam injected and Miller cycle diesel engine by using a simulation model based on the finite-time thermodynamics. The model is validated with experimental data and the effects of various engine design and operating parameters such as cycle Temperature Ratio, cycle pressure Ratio, friction coefficient, engine speed, mean piston speed, stroke length, inlet Temperature, inlet pressure, equivalence Ratio, compression Ratio, steam Ratio, retarding angle and bore-stroke length Ratio on the effective power and effective efficiency are investigated. Furthermore, the energy losses originating from incomplete combustion, friction, heat transfer and exhaust output are demonstrated by using figures. The results show that the engine performance increases with increasing some parameters such as cycle Temperature Ratio, cycle pressure Ratio, inlet pressure; with decreasing some parameters such as friction coefficient, inlet Temperature, steam Ratio, retarding angle of intake valve closing. However, the engine performance could increase or decrease with respect to different conditions for some parameters such as engine speed, mean piston speed, stroke length, equivalence Ratio and compression Ratio.
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comprehensive performance analyses and optimization of the irreversible thermodynamic cycle engines tce under maximum power mp and maximum power density mpd conditions
Applied Thermal Engineering, 2015Co-Authors: Guven Gonca, Bahri Sahin, Yasin Ust, Adnan ParlakAbstract:Abstract This paper presents comprehensive performance analyses and comparisons for air-standard irreversible thermodynamic cycle engines (TCE) based on the power output, power density, thermal efficiency, maximum dimensionless power output (MP), maximum dimensionless power density (MPD) and maximum thermal efficiency (MEF) criteria. Internal irreversibility of the cycles occurred during the irreversible-adiabatic processes is considered by using isentropic efficiencies of compression and expansion processes. The performances of the cycles are obtained by using engine design parameters such as isentropic Temperature Ratio of the compression process, pressure Ratio, stroke Ratio, cut-off Ratio, Miller cycle Ratio, exhaust Temperature Ratio, cycle Temperature Ratio and cycle pressure Ratio. The effects of engine design parameters on the maximum and optimal performances are investigated.
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performance maps for an air standard irreversible dual miller cycle dmc with late inlet valve closing livc version
Energy, 2013Co-Authors: Guven Gonca, Ahri SahiAbstract:In this paper, a performance analysis based on the power output, thermal efficiency, maximum power output (MP) and maximum thermal efficiency (MEF) criteria have been carried out for an air-standard irreversible Dual–Miller cycle (DMC) with late inlet valve closing (LIVC) version which covers internal irreversibility owing to the irreversible-adiabatic processes. The thermal efficiency and power output are acquired based on the stroke Ratio, cut-off Ratio, pressure Ratio, miller cycle Ratio, cycle Temperature Ratio, cycle pressure Ratio and the isentropic efficiencies of compression and expansion processes of the cycle. The influences of cycle Temperature Ratio and cycle pressure Ratio of the DMC on the optimum performances are examined.
Sofiane Bourouaine - One of the best experts on this subject based on the ideXlab platform.
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stochastic heating differential flow and the alpha to proton Temperature Ratio in the solar wind
The Astrophysical Journal, 2013Co-Authors: Eliot Quataert, Benjamin D G Chandran, Daniel Verscharen, J C Kasper, Philip A Isenberg, Sofiane BourouaineAbstract:We extend previous theories of stochastic ion heating to account for the motion of ions along the magnetic field B . We derive an analytic expression for the Temperature Ratio T ?i/T ?p in the solar wind assuming that stochastic heating is the dominant ion heating mechanism, where T ?i is the perpendicular Temperature of species i and T ?p is the perpendicular proton Temperature. This expression describes how T ?i/T ?p depends upon U i and ??p, where U i is the average velocity along B of species i in the proton frame and ??p is the Ratio of the parallel proton pressure to the magnetic pressure, which we take to be 1. We compare our model with previously published measurements of alpha particles and protons from the Wind spacecraft. We find that stochastic heating offers a promising explanation for the dependence of T ??/T ?p on U ? and ??p when the fractional cross helicity and Alfv?n Ratio at the proton-gyroradius scale have values that are broadly consistent with solar-wind measurements. We also predict how the Temperatures of other ion species depend on their drift speeds.
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stochastic heating differential flow and the alpha to proton Temperature Ratio in the solar wind
arXiv: Solar and Stellar Astrophysics, 2013Co-Authors: Eliot Quataert, Benjamin D G Chandran, Daniel Verscharen, J C Kasper, Philip A Isenberg, Sofiane BourouaineAbstract:We extend previous theories of stochastic ion heating to account for the motion of ions along the magnetic field. We derive an analytic expression for the ion-to-proton perpendicular Temperature Ratio in the solar wind for any ion species, assuming that stochastic heating is the dominant ion heating mechanism. This expression describes how this Temperature Ratio depends upon the average velocity of the ions along the magnetic field direction and the Ratio of the parallel proton pressure to the magnetic pressure. We compare our model with previously published measurements of alpha particles and protons from the WIND spacecraft. We find that stochastic heating offers a promising explanation for these measurements when the fractional cross helicity and Alfven Ratio at the proton-gyroradius scale have values that are broadly consistent with solar-wind measurements.
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on the relative speed and Temperature Ratio of solar wind alpha particles and protons collisions versus wave effects
The Astrophysical Journal, 2011Co-Authors: Sofiane Bourouaine, Eckart Marsch, Fritz M NeubauerAbstract:We study the relative flow speed and the Temperature Ratio of alpha particles and protons and their connections to the helium ion abundance, the collisional age, and the power of transverse fluctuations within the inertial range. It is found that the alpha-to-proton Temperature Ratio, T{sub {alpha}}/T{sub p} , anti-correlates with the helium ion abundance. Despite a relatively high collisional age and small wave power, the Ratio T{sub {alpha}}/T{sub p} can reach comparatively high values (even above 2) whenever the helium ion abundance is below about 0.02. In contrast, the differential speed of alpha particles with respect to protons is correlated with the total wave power and anti-correlated with the collisional age. Ultimately, the individual heating of each ion species is positively correlated with the total wave power. Our findings suggest that a high-friction collision could be efficient in reducing the differential speed between alpha particles and protons, but appears not to be sufficient to equalize the alpha and proton Temperatures, i.e., to make T{sub {alpha}} {approx_equal} T{sub p} . This is a hint that the local wave heating process is acting on a timescale shorter than the collision time.
