Journal: International Journal of Thermal Sciences

Abbreviation

Int. j. therm. sci.

Publisher

Elsevier

Journal Volumes

ISSN

1290-0729
1778-4166

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Publications 1 - 10 of 18
  • Heat transfer on a plate beneath an external uniform shear flow
    Item type: Journal Article
    Magyari, E.; Weidman, P.D. (2006)
    International Journal of Thermal Sciences
  • Exact analytical results for the thermosolutal MHD Marangoni boundary layers
    Item type: Journal Article
    Magyari, E.; Chamkha, A.J. (2008)
    International Journal of Thermal Sciences
  • The Entrainment Theorem for the Darcy free convection over a permeable vertical plate
    Item type: Journal Article
    Magyari, Eugen; Rees, D. Andrew S. (2008)
    International Journal of Thermal Sciences
  • CFD modeling of convective scalar transport in a macroporous material for drying applications
    Item type: Journal Article
    Lal, Sreeyuth; Lucci, Francesco; Defraeye, Thijs; et al. (2018)
    International Journal of Thermal Sciences
  • Determination of thermal radiative properties of packed-bed media containing a mixture of polydispersed particles
    Item type: Journal Article
    Jäger, Klaus; Lipiński, Wojciech; Katzgraber, Helmut G.; et al. (2009)
    International Journal of Thermal Sciences
  • A moving finite line source model to simulate borehole heat exchangers with groundwater advection
    Item type: Journal Article
    Molina-Giraldo, Nelson; Blum, Philipp; Zhu, Ke; et al. (2011)
    International Journal of Thermal Sciences
  • Large eddy simulations of wall heat transfer and coherent structures in mixed convection over a wavy wall
    Item type: Journal Article
    Kuhn, Simon; Kenjeres, Sasa; Rudolf von Rohr, Philipp (2010)
    International Journal of Thermal Sciences
  • Large-eddy simulation of wind-driven flame in the atmospheric boundary layer
    Item type: Journal Article
    Ong, Robert H.; Patruno, Luca; He, Y.; et al. (2022)
    International Journal of Thermal Sciences
    The interaction between the natural ambient winds found in the atmospheric boundary layer (ABL) and buoyant flames is crucial in broad applications in the scientific and engineering fields. Unlike the buoyancy-driven pool fires in still air that have been studied extensively, the complexity of physics changes significantly in wind presence. This study aims at analysing the characteristics of boundary-layer turbulence in the presence of large fires. The eddy dissipation concept, finite volume discrete ordinate method, and one k-equation model are used for combustion, thermal radiation, and sub-grid scale closure using the Large-Eddy Simulation (LES), respectively. A numerical model on simple cases is validated first to assess its capability to reproduce available experimental observations for a purely buoyant fire in still air. A forced-flow boundary layer combustion in a small chamber with a smooth inflow is further considered. In general, good agreement between the simulation results and available experimental data was achieved for temperature and velocity profiles. The unsteady inflow condition used to consider incoming atmospheric turbulence is generated through a precursor simulation. The wind interaction with the line fire changes the atmospheric boundary layer profile affecting the heat transfer ahead of the flame, thereby creating counter-rotating structures downstream. It is shown that the buoyancy-dominated flow due to the flame reaction induced local pressure variation and perturbed shear flow near the ground, thereby altering the wind speed through which the plume rises. Richardson number was also used as a dominant non-dimensional group to analyse the variation of enhanced flow vertical velocity with distance from the fire source. Thus, it is understood that the pronounced longitudinal shear spreading at the surface affects the behaviour of short term or puff releases, suggesting the shedding of small eddies during the combustion process.
  • Evaluating the influence of thermal dispersion on temperature plumes from geothermal systems using analytical solutions
    Item type: Journal Article
    Molina-Giraldo, Nelson; Bayer, Peter; Blum, Philipp (2011)
    International Journal of Thermal Sciences
  • Broadband, highly reflective thermal protection systems, exploiting photonic additives
    Item type: Journal Article
    Christidis, George; Koch, Ueli; Gusarov, Andrey V.; et al. (2021)
    International Journal of Thermal Sciences
    Photonic additives have been investigated as a means to enhance the efficiency of thermal protection systems (TPS) against the adverse effects of thermal radiation. State-of-the-art TPS consist of carbon fibers embedded in a phenolic resin matrix. During operation, the TPS is consumed because it is exposed to an excess heat flux, a large fraction of which is due to thermal radiation. Here, we show that a properly modeled and designed additive-impregnated TPS can block a considerable part of this heat influx and quantify how different control parameters, in particular the additives’ amount, placement and alignment, influence the achieved photonic enhancement. More specifically, the intrinsic reflectivity of 8.5% of a conventional TPS can been improved to values exceeding 85% by controllably inserting additives, consisting of a Ta/[SiO2/TiO2]6 heterostructure, here referred to as Type 1, an ideal, optimized, high and broadband reflector. Nevertheless, even simple, commercially available additives composed of TiO2/Al2O3/TiO2, here referred to as Type 2, provide a high reflectivity enhancement with values of up to 76%, when used in larger quantities. The simulations of this work are based on the Monte Carlo Ray Tracing (MCRT) method. The MCRT simulation method has been validated against experiment, using the structure and experiments from a literature reference. Our analysis method allows one to design and model the performance of photonically enhanced TPS that operate in high-flux, radiative conditions, like those expected in future aerospace re-entry missions or next-generation, gas turbines and thermophotovoltaic plants and provides a viable option for efficiently enhancing a TPS.
Publications 1 - 10 of 18