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International audience; This experimental study deals with the impingement of sprays on a heated wall in close to semi-industrial conditions. Therefore, an experimental setup was specifically designed: high liquid mass flux (up to 8 kg/m 2 /s), large droplets (up to 300 lm) and high surface temperature widely above the Leidenfrost point (up to 800 °C). The surface to be cooled is a 175 mm diameter nickel disk with 5 mm thickness heated by electromagnetic induction. The spraying devices consist in full cone sprays. Several studies, performed under these particular conditions, has allowed characterizing the heat flux removed by the spray by using techniques based on thermocouples or infrared thermography (IRT). However, to investigate more finely the heat transfer mechanism, it is necessary to measure the droplet temperature but, to date, no measurement for sprays are available in the literature. Therefore, the objective of the present work is to demonstrate the ability of the three-color Laser Induced Fluorescence (3cLIF) to meet this challenge. The combination of the 3cLIF with a Phase Doppler system allows also determining the droplet temperature per size class before and after impact. By adding the IRT measurements combined to an inverse heat conduction model, an energy balance is done in order to estimate the evaporated liquid mass. The influence of the normal Weber number on the liquid vaporization is investigated by using three sprays (Normal Weber numbers up to about 1500). Thereby, main results show that the droplets temperature after impact increases with the incident Weber number before to reach a plateau, attributed to the apparition of the splashing regime. The analysis of the energy balance shows that the mass of evaporated liquid decreases with the incident Weber number and the droplet heating. These first results are in well agreement with previous works conducted with single calibrated droplets, validating as the same time the use of combined 3cLIF-PDA measurements in the case of sprays.

International audience; The solution of the linear, inverse, transient heat conduction problem (IHCP) in a cylindrical geometry is analysed. The rotating cylinder under investigation is experiencing boiling convection induced by the impingement of a water jet. The initial temperature is known, additional temperature measurements in time are taken with sensors positioned at a constant radius within the solid material, and the estimation of the wall heat flux at the external radius is sought. First, simulated temperature measurements inside the cylinder are processed in order to be used to estimate the wall heat flux. When noise is present in the data, some of the simulated results obtained using the least squares method exhibit oscillatory behavior, but these large oscillations are substantially reduced by the implementation of a regularization technique. Real experimental data are also used for the wall condition estimation and for the subsequent building of local boiling curves are plotted and discussed. The question of the possible effect of a temperature dependent conductivity on the reconstructed wall condition is also considered.

International audience; Hydrodynamic and thermal analysis of suspension flows is a difficult but fundamental task for the sterilization problems of particle charged fluids in food industries and also in any process where we can find flow with seeded particles. Nowadays, the influence of solid suspended particles on the flow is not yet a well known problem. Nevertheless, the solid particles have a strong influence on the rheological mixture's behaviour. The new approach of these solid-liquid suspension flows that we propose is based on experimental data and theoretical considerations. We use hard sphere approach in order to model the pressure drop assuming the mixture as an effective continuous medium. On these bases, we present a model of the heat transfer at the wall.

International audience; The effect of hydrodynamic conditions on the enhancement of heat transfer for single phase flow is studied using a combination of experimental data and numerical data. Experiments have been conducted for a wide range of Reynolds numbers, (0

International audience; A hot moving (rotating) cylinder was heated up to 500-600°C and then was cooled by a planar water jet impinging on a line parallel to the symmetry axis. The time dependent wall temperature was measured using embedded thermocouples and the corresponding wall heat fluxes were estimated through an inverse conduction method. In a recent paper, we showed that cooling rates depend on the subcooled temperature of the jet, the velocity of the jet and the surface-to-jet velocity ratio. Since the initial temperature of the cylinder was higher than the Leidenfrost temperature, we observed all the boiling regimes from film boiling to nucleate boiling. The objectives of this paper are firstly to describe the current conditions which exist in the Run Out Table in hot rolling mills, secondly to review the main experimental studies dedicated to jet cooling which have led to modelling heat transfer in boiling conditions and finally to propose new correlations taking into account the velocity of the wall.