The Experts below are selected from a list of 39063 Experts worldwide ranked by ideXlab platform
Jing Li - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic and economic investigation of a screw expander based direct steam generation solar cascade rankine cycle system using water as thermal Storage Fluid
Applied Energy, 2017Co-Authors: Jing Li, Pengcheng Li, Yuehong Su, Jie JiAbstract:Solar electricity generation system (SEGS) which employs cascade steam-organic Rankine cycle (SORC) and steam screw expander (SE) is promising due to the high efficiency at moderate heat source temperature. This paper puts a special emphasis on heat Storage and thermo-economic evaluation. Preferable operating temperature of the system is first clarified on the basis of SE characteristics. The temperature-dependent permissible stress of steam accumulator is modelled and the capital cost is investigated. Comparison between the direct steam generation (DSG) SEGS and an indirect one using thermal oil is made at a power capacity of 1MW and Storage of 6.5h. The results indicate the DSG system has both thermodynamic and economic superiorities. The hot side temperature (TH) of SORC generally does not exceed 250°C to achieve an optimum solar thermal power efficiency. Given radiation of 750W/m2, the maximum efficiency (ηT,m) is 14.3% with a corresponding TH around 240°C. The material cost of pressure vessels is 2.55 million RMB. For the indirect system, the optimal TH is about 230°C and ηT,m approximates to 13.2% and the estimated oil cost is 7.92 million RMB. It is recommended to adopt steam accumulators in the SE-driven SEGS.
Raffaella Di Dona - One of the best experts on this subject based on the ideXlab platform.
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Optimization of medium temperature direct steam generation solar plant
Energy Procedia, 2018Co-Authors: Paolo Iodice, Giuseppina Langella, Amedeo Amoresano, Raffaella Di DonaAbstract:Abstract The object of this study is the plan of original power systems of reduced size, investigating on the energetic benefits of a solar plant with parabolic trough collectors and steam screw expander. Usually, medium temperature solar systems need to be coupled with organic Fluids cycles which allow high specific expansion work at low temperature and pressure, so involving a heat exchange between two Fluids with the consequent exergetic degradation of the available thermal energy. This paper focuses on the steam screw expander-based solar thermal electricity system with water as heat transfer and Storage Fluid, clarifying in which operating conditions this simple plant layout could be convenient in terms of energy saving. A mathematical model on the system part-load behaviour is analysed and the optimum working conditions of this solar system were determined, revealing variations of maximum solar thermal power efficiency with operating pressure ratio and beam solar radiation.
Jie Ji - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic and economic investigation of a screw expander based direct steam generation solar cascade rankine cycle system using water as thermal Storage Fluid
Applied Energy, 2017Co-Authors: Jing Li, Pengcheng Li, Yuehong Su, Jie JiAbstract:Solar electricity generation system (SEGS) which employs cascade steam-organic Rankine cycle (SORC) and steam screw expander (SE) is promising due to the high efficiency at moderate heat source temperature. This paper puts a special emphasis on heat Storage and thermo-economic evaluation. Preferable operating temperature of the system is first clarified on the basis of SE characteristics. The temperature-dependent permissible stress of steam accumulator is modelled and the capital cost is investigated. Comparison between the direct steam generation (DSG) SEGS and an indirect one using thermal oil is made at a power capacity of 1MW and Storage of 6.5h. The results indicate the DSG system has both thermodynamic and economic superiorities. The hot side temperature (TH) of SORC generally does not exceed 250°C to achieve an optimum solar thermal power efficiency. Given radiation of 750W/m2, the maximum efficiency (ηT,m) is 14.3% with a corresponding TH around 240°C. The material cost of pressure vessels is 2.55 million RMB. For the indirect system, the optimal TH is about 230°C and ηT,m approximates to 13.2% and the estimated oil cost is 7.92 million RMB. It is recommended to adopt steam accumulators in the SE-driven SEGS.
Mehrdji Hemati - One of the best experts on this subject based on the ideXlab platform.
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experimental hydrodynamic study of gas particle dense suspension upward flow for application as new heat transfer and Storage Fluid
Canadian Journal of Chemical Engineering, 2015Co-Authors: Gilles Flamant, Benjamin Boissiere, Renaud Ansart, Daniel J Gauthier, Mehrdji HematiAbstract:This paper focuses on a new concept of Heat Transfer Fluid (HTF) for Concentrating Solar Plants (CSP) applications through Fluidized bed. CSP plants with very high concentration (such as solar tower plant technology) offer good efficiencies because of high operating temperatures. CSP efficiency could be greatly increased through more efficient HTF. Molten salts, mineral oils, water and air have some of the following drawbacks: limited range of operating temperatures, corrosiveness, high pressure, low energy Storage capacity and toxicity. To replace classical HTF, Dense Particle Suspension (DPS) Fluidized with air (approximately 40% of solid) is proposed. DPS has a volume heat capacity similar to those of liquid HTF, does not need pressurization, is safe, inert and is only limited by the maximal working temperature of the receiver material (1100 K), thus opening new opportunities for high efficiency thermodynamic cycles. This work is the hydrodynamic study of a gassolid dense suspension upward flow at ambient temperature, in a vertical 2‐tube bundle of small diameter tubes, which have their bottom immersed in a slightly pressurized Fluidized bed (pressure approximately equal to the ratio of the solid weight in a tube over its cross section area). This type of flow is yet implemented in the field of hyper‐dense phase vertical conveying of powders and it is currently under development for solar receivers using dense suspensions of particles as heat transfer and Storage medium. This application was patented by Flamant and Hemati in 2010 (France 1058565 (2010) CNRS/INP Toulouse, G. Flamant, H. Hemati; PCT Extension, No. WO 2012/052661 A2), and its development is funded by the European Commission. In this technological breakthrough, the concentrated solar energy is collected, carried and stored directly by the fine particles flowing upward, with a suspension void fraction close to that of a dense Fluidized bed. Contrary to circulating Fluidized bed “risers”, it offers a good contact area between the wall and the particles. The important hydrodynamic and thermal coupling required a step‐by‐step approach. Ambient flows had to be understood and controlled first. Thus a 2‐pass “cold” mock‐up, each pass composed of two vertical parallel tubes, was built. Pressure drop, solid weight and helium volume fraction measurements demonstrated the ability to handle a regular solid upward flow (imperative here), with solid flow rates from 20 to 130 kg/h, with void fractions from 0.57 to 0.63 and with an even distribution of the solid flow rate between the tubes. Moreover, the governing parameters of this flow were established as: the solid feeding flow rate, the Fluidization velocity, the solid holdup, the freeboard pressure and the aeration velocity. The secondary air injection, also called “aeration”, is the most important parameter for the stability and the even distribution of the total solid flow rate in the tubes. The 1D modelling of the suspension flow in the tubes was also performed in the flow direction. The flow structure was described using the bubble‐emulsion model formalism, and by adding the solid entrainment by the bubble wake. Predictions of the model are compared with the experimental measurements of driving pressure and axial pressure profile along the tubes.
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Experimental Hydrodynamic Study of Gas‐Particle Dense Suspension Upward Flow for Application as New Heat Transfer and Storage Fluid
Canadian Journal of Chemical Engineering, 2014Co-Authors: Benjamin Boissiere, Gilles Flamant, Renaud Ansart, Daniel Gauthier, Mehrdji HematiAbstract:This paper focuses on a new concept of Heat Transfer Fluid (HTF) for Concentrating Solar Plants (CSP) applications through Fluidized bed. CSP plants with very high concentration (such as solar tower plant technology) offer good efficiencies because of high operating temperatures. CSP efficiency could be greatly increased through more efficient HTF. Molten salts, mineral oils, water and air have some of the following drawbacks: limited range of operating temperatures, corrosiveness, high pressure, low energy Storage capacity and toxicity. To replace classical HTF, Dense Particle Suspension (DPS) Fluidized with air (approximately 40% of solid) is proposed. DPS has a volume heat capacity similar to those of liquid HTF, does not need pressurization, is safe, inert and is only limited by the maximal working temperature of the receiver material (1100 K), thus opening new opportunities for high efficiency thermodynamic cycles. This work is the hydrodynamic study of a gassolid dense suspension upward flow at ambient temperature, in a vertical 2‐tube bundle of small diameter tubes, which have their bottom immersed in a slightly pressurized Fluidized bed (pressure approximately equal to the ratio of the solid weight in a tube over its cross section area). This type of flow is yet implemented in the field of hyper‐dense phase vertical conveying of powders and it is currently under development for solar receivers using dense suspensions of particles as heat transfer and Storage medium. This application was patented by Flamant and Hemati in 2010 (France 1058565 (2010) CNRS/INP Toulouse, G. Flamant, H. Hemati; PCT Extension, No. WO 2012/052661 A2), and its development is funded by the European Commission. In this technological breakthrough, the concentrated solar energy is collected, carried and stored directly by the fine particles flowing upward, with a suspension void fraction close to that of a dense Fluidized bed. Contrary to circulating Fluidized bed “risers”, it offers a good contact area between the wall and the particles. The important hydrodynamic and thermal coupling required a step‐by‐step approach. Ambient flows had to be understood and controlled first. Thus a 2‐pass “cold” mock‐up, each pass composed of two vertical parallel tubes, was built. Pressure drop, solid weight and helium volume fraction measurements demonstrated the ability to handle a regular solid upward flow (imperative here), with solid flow rates from 20 to 130 kg/h, with void fractions from 0.57 to 0.63 and with an even distribution of the solid flow rate between the tubes. Moreover, the governing parameters of this flow were established as: the solid feeding flow rate, the Fluidization velocity, the solid holdup, the freeboard pressure and the aeration velocity. The secondary air injection, also called “aeration”, is the most important parameter for the stability and the even distribution of the total solid flow rate in the tubes. The 1D modelling of the suspension flow in the tubes was also performed in the flow direction. The flow structure was described using the bubble‐emulsion model formalism, and by adding the solid entrainment by the bubble wake. Predictions of the model are compared with the experimental measurements of driving pressure and axial pressure profile along the tubes.
Paolo Iodice - One of the best experts on this subject based on the ideXlab platform.
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Optimization of medium temperature direct steam generation solar plant
Energy Procedia, 2018Co-Authors: Paolo Iodice, Giuseppina Langella, Amedeo Amoresano, Raffaella Di DonaAbstract:Abstract The object of this study is the plan of original power systems of reduced size, investigating on the energetic benefits of a solar plant with parabolic trough collectors and steam screw expander. Usually, medium temperature solar systems need to be coupled with organic Fluids cycles which allow high specific expansion work at low temperature and pressure, so involving a heat exchange between two Fluids with the consequent exergetic degradation of the available thermal energy. This paper focuses on the steam screw expander-based solar thermal electricity system with water as heat transfer and Storage Fluid, clarifying in which operating conditions this simple plant layout could be convenient in terms of energy saving. A mathematical model on the system part-load behaviour is analysed and the optimum working conditions of this solar system were determined, revealing variations of maximum solar thermal power efficiency with operating pressure ratio and beam solar radiation.