PDF Publication Title:
Text from PDF Page: 123
Chapter 4 The solar field is modelled as a single loop of parabolic collectors connected in series: the large ratio between length and diameter allows a one-dimensional (1D) discretization of the absorber tube. The finite-volume approach with an upwind scheme for mass flow and specific enthalpy is used [65]. The model is implemented connecting 2 sub−components: the Flow1D model available from the ThermoPower library [62], and the newly developed SolAbs model , which interacts through a distributed thermal connector [63]. Flow1D models the working fluid flow through the absorber, or heat collecting element (HCE), accounting for friction losses. The flow regime in the HCE is always turbulent, and the fluid- wall convective heat transfer coefficient U [kWT m−2 ◦C−1] is modelled, in off-design condition, according to the relation U = Udes · (m ̇ fluid/ m ̇ fluid,des)0.65. SolAbs models the dynamic 1D thermal energy balance on a HCE cross section. It accounts for conduction and storage in the metal pipe, convection and radiation in the vacuum chamber between the glass envelope and the metal pipe, conduction and storage in the glass envelope, convection and radiation transfers with the ambient air [67]. SolAbs implements the relations between the environmental parameters (DNI, θinc, Tamb, and Vwind), and the axial temperature distribution along the absorber. Both the thermal power lost to the environment q ̇hl (see A.1), and the power transferred to the fluid can thus be evaluated. The pump circulating the fluid through the solar field is modelled by prescribing the flow rate passing through the machine (see also sec. 4.5.6), and by neglecting the specific enthalpy change across it. This follows the assumption that the dynamics of the recirculation pump is negligible compared to that of the solar collector, and that local flow controllers will be used in the solar field. The complete solar collector model has been validated with reference data from [67]. STORAGE SYSTEM The thermocline storage is modelled following a 1D, finite volumes approach: the tank, supposed cylindrical, is discretized along its axis [70]. As anticipated, constant pressure is prescribed in the tank, thus implicitly accounting for an ideal pressurization system. The model evaluates changes in the volume of fluid, as a consequence of thermal expansion and mass balance. The implemented dynamic mass and energy balance equations account for the conductive heat transfer in the fluid and in the metal wall (along the vessel height), and the heat transfer between the wall and the fluid. Thermal energy storage in the metal wall is neglected, and three constant overall heat transfer coefficients are defined to model the thermal power lost to the environment from the top roof, the foundation, and the lateral walls of the tank. The four connecting flanges have a fixed position: the first volume to the top is linked to the outlet of the SF and to the inlet of the flashing valve, and the last volume to the bottom is connected to the outlet of the regenerator and to the inlet of the solar field pump. The turbulence mixing effects due to the introduction of the fluid on the stratification in the tank are neglected. Due to the numerical diffusion of the finite volume method, it is necessary to employ a fairly high number of nodes (at least N = 30) in order to model the thermocline that develops in the tank. Also note that the delay between the temperature changes at the top inlet and the corresponding changes at the top outlet is represented in the model as the dynamics of a well-stirred volume having (1/N)th of the total volume, and is thus typically underestimated for such large values of N. This represents a worst-case scenario in terms of the burden imposed on the ORC system controllers by the fast variations of the SF outlet temperature. Since it is very hard to represent this dynamics accurately (detailed 3D CFD models would be required), this approximation is arguably the safest for a system-level dynamic model. The thermocline storage model has been validated based on experimental data from the open literature [70]. The valve performing the flashing process is modelled assuming ideal control of the thermo- 112PDF Image | New Concepts FOR Organic Rankine Cycle Power Systems
PDF Search Title:
New Concepts FOR Organic Rankine Cycle Power SystemsOriginal File Name Searched:
PhDTesis_ECasati.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)