CRS4 Report

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https://hdl.handle.net/11050/59
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Mostra il contenuto di CRS4 Report per Subject "3D thermal analysis"

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    Analysis and optimisation of a gas-cooled pipe for solar thermal energy production using parabolic collectors
    (2000-03) Aragonese, Cosimo; Buono, Stefano; Maciocco, Luca; Moreau, Vincent; Sorrentino, Luca
    In the framework of the design of a solar thermal power plant proposed by ENEA, the activity carried out by CRS4 on the thermal-fluid-dynamic simulation of a gas-cooled pipe irradiated by a parabolic solar collector is described in this paper. Two methods have been adopted in parallel: a simplified one-dimensional approach and a Computational-Fluid-Dynamics (CFD) three-dimensional approach. The first method was used to build a tool able to give quick answers to parameters changes with an acceptable degree of accuracy. The CFD analysis is used both to validate 1D-model results and to study in details all 3D physical phenomena. The multi-zone one-dimensional model developed at CRS4 is described first. The pipe is split along its axis into a discrete number (typically 100) of sub-domains. Each sub-domain is split further on into five different zones, corresponding to the various components of the pipe. All the main energy-exchange mechanisms between the various parts of the pipe have been implemented, resulting in a system of five equations for each sub-domain, solved iteratively within an EXCEL framework. The 3D-CFD model is then described. The model is fully parametric, allowing a quick variation of the geometrical parameters of the system. Convection, conduction and thermal radiation heat exchanges are solved in a coupled way. The model can give any information about field variables of fluids and solid structures as well as all energy balances. The two models have been used for a parametric study of the effect of the pipe diameter variation on the system efficiency. Although not negligible differences between the two models can be noticed concerning local energy balances, the error on the evaluation of the system efficiency is order 1%. The result of the optimization was practically the same for the two models.
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    Thermal analysis of the TOF lead target at CERN
    (2001-03-16) Aragonese, Cosimo; Buono, Stefano; Maciocco, Luca; Moreau, Vincent; Sorrentino, Luca
    The lead target at the Time Of Flight (TOF) facility at CERN, currently under commissioning, undergoes relevant temperature transients due to the intensity of the four 20 GeV/c pulses of 7 x 1012 protons, carrying an energy of 21.4 kJ delivered in 7 ns each. A 3D thermal analysis of the target system in both steady-state and transient conditions has been performed using the finite volume commercial code StarCD coupled with the results from Fluka simulations. Results show that the maximum temperature inside the lead target using the parameters of the TOF commissioning phase (4 pulses every 1.2 s in a 14.4 s super-cycle) is 127°C at steady-state operations, which is an acceptable value, compatible with safe and durable target operations. A significant improvement could be obtained by doubling the beam size (108°C maximum temperature in the bulk of the central block). The transients coming from the pulsed operation are not such as to create structural problems related to thermal fatigue. It is interesting to notice that the thermal oscillation in the hottest point in the bulk of the central block is much lower in the case where the 4 pulses are spaced of 3.6 s during the PS super-cycle (about 20°C), than in the case where they are spaced of only 1.2 s (about 40° C).