Browsing by Author "Campo, Antonio"

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    Assessing the Uncertainty in Transient Heat Conduction Within Large Plates, Long Cylinders, and Spheres
    (TAYLOR & FRANCIS INC, 2012) Lira, Ignacio; Campo, Antonio
    Relevant quantities in transient heat conduction within solids include the temperature distribution and the total energy released up to a given time. Expressions for these quantities are well known in the case of large plates, long cylinders, and spheres initially at a uniform temperature and subject to convective boundary conditions. Because the heat transfer coefficient usually is not known accurately, it is of interest to assess how the uncertainty associated with its estimated value propagates into the uncertainties of the local temperatures inside these three bodies and of the total energy released from them. In this paper a calculation procedure in agreement with current international recommendations is developed for this purpose.
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    Numerical heat transfer in annular fins of curved profile formed with the intersection of two equal circles
    (2021) Celentano, Diego; Campo, Antonio
    Purpose The purpose of this paper is to investigate the heat transfer attributes of annular fins with quarter circle profile in terms of the Biot number Bi and the radius ratio r(r). The latter corresponds to the internal radius of the tube divided by the length of the fin in question. Design/methodology/approach To this end, the governing two-dimensional (2-D) heat conduction equation in cylindrical coordinates is numerically solved via finite element analysis for different Bi (i.e., 0.1, 1 and 5) and r(r) (i.e., 0.5, 1 and 2). Findings The obtained results for the mid-plane and surface temperatures show that these profiles, which exhibit nearly r(r)-independent responses, only present one-dimensional (1-D) radially linear distributions for the case Bi = 1. For Bi = 0.1, the temperature profiles also possess a 1-D character but with a clearly defined concave pattern. Finally, for Bi = 5, a 2-D temperature field in a wide zone from the fin base is achieved with a convex pattern for the mid-plane and surface temperatures. Originality/value Exhaustive assessment of the heat transfer in annular fins with quarter circle profile in terms of different Biot numbers and radius ratios
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    One-Dimensional Versus Two-Dimensional Behavior of Isachenko's Optimal Straight Fin with Quarter-Circle Profile
    (AMER INST AERONAUT ASTRONAUT, 2012) Campo, Antonio; Celentano, Diego J.
    A study was conducted to investigate the behavior of the 2-D temperature distributions in a straight fin with a quarter-circle profile through the powerful finite element method. The computed numerical 2-D temperatures were post-analyzed to clarify in a natural way the circumstances under which the general 2-D heat equation degraded into a simple quasi 1-D heat equation for modeling Isachenko's optimal straight fin. This realistic interconnectivity was presented in graphs and in a table containing the transverse biot number (Bit). The structured finite element mesh was constructed with three-noded isoparametric triangular elements. Smaller three-noded isoparametric triangular elements were also constructed in the vicinity of the curved surface extending from the fin base to the fin tip for enhanced accuracy. Numerical calculations of the 2-D dimensionless temperatures for representative transverse Bit were performed with an in-house finite element code.
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    Prediction of the temperature-time history in ordinary bodies induced by surface heat flux utilizing the enhanced method of discretization in time and the finite difference method
    (2023) Campo, Antonio; Celentano, Diego; Masip, Yunesky
    PurposeThe purpose of this paper is to address unsteady heat conduction in two subsets of ordinary bodies. One subset consists of a large plane wall, a long cylinder and a sphere in one dimension. The other subset consists of a short cylinder and a large rectangular bar in two dimensions. The prevalent assumptions in the two subsets are: constant initial temperature, uniform surface heat flux and thermo-physical properties invariant with temperature. The engineering applications of the unsteady heat conduction deal with the determination of temperature-time histories in the two subsets using electric resistance heating, radiative heating and fire pool heating. Design/methodology/approachTo this end, a novel numerical procedure named the enhanced method of discretization in time (EMDT) transforms the linear one-dimensional unsteady, heat conduction equations with non-homogeneous boundary conditions into equivalent nonlinear "quasi-steady" heat conduction equations having the time variable embedded as a time parameter. The equivalent nonlinear "quasi-steady" heat conduction equations are solved with a finite difference method. FindingsBased on the numerical computations, it is demonstrated that the approximate temperature-time histories in the simple subset of ordinary bodies (large plane wall, long cylinder and sphere) exhibit a perfect matching over the entire time domain 0 < t < infinity when compared against the rigorous exact temperature-time histories expressed by classical infinite series. Furthermore, using the method of superposition of solutions in the convoluted subset (short cylinder and large rectangular crossbar), the same level of agreement in the approximate temperature-time histories in the simple subset of ordinary bodies is evident. Originality/valueThe performance of the proposed EMDT coupled with a finite difference method is exhaustively assessed in the solution of the unsteady, one-dimensional heat conduction equations with prescribed surface heat flux for: a subset of one-dimensional bodies (plane wall, long cylinder and spheres) and a subset of two-dimensional bodies (short cylinder and large rectangular bar).