Free convective flow in a cubical cavity loaded with copper-water nanofluid was examined numerically by employing a non-homogeneous dynamic model, which is physically more realistic in representing nanofluids than homogenous ones. The cavity was introduced to a horizontal magnetic field from the left sidewall. Both the cavity’s vertical left and right sidewalls are preserved at an isothermal cold temperature (T_c). The cavity includes inside it four isothermal heating blocks in the middle of the top and bottom walls. The other cavity walls are assumed adiabatic. Simulations were performed for solid volume fraction ranging from (0 ≤ ϕ ≤ 0.06), Rayleigh number varied as (10³ ≤ Ra ≤ 10⁵), the Hartmann number varied as (0 ≤ Ha ≤ 60), and the diameter of nanoparticle varied as (10 nm ≤ d_p ≤ 130 nm). It was found that at (d_p = 10 nm), the average Nusselt number declines when Ha increases, whereas it increases as (Ra) and (ϕ) increase. Furthermore, the increasing impact of the magnetic field on the average Nusselt number is absent for (Ra = 10³), and this can be seen for all values of (ϕ). However, when (d_p) is considered variable, the average Nusselt number was directly proportional to (Ra) and (ϕ) and inversely proportional to (d_p).

This article consists of a numerical study of natural convection heat transfer in three-dimensional cavity filled with nanofluids. This configuration is heated by a partition maintained at a hot constant and uniform temperature T_H. The right and left vertical walls are kept at a cold temperature T_C while the rest is adiabatic. The fluid flow and heat transfer in the cavity are studied for different sets of the governing parameters, namely, the nanofluid type, the Rayleigh number Ra=10³, 10⁴, 10⁵, and 10⁶, and the volume fraction Ф varying between Ф=0 and 0.1. The obtained results show a positive effect of the volume fraction and the Rayleigh number on the heat transfer improvement. The analysis of the results related to the heat transfer shows that the copper-based nanofluid guarantees the best thermal transfer. In addition, the increase of the heating section size and Ra leads to an increased amount of heat. Similarly, increasing the volume fraction improves the intensification of the flow and increases the heat exchange.

Fouling is a known dairy industry issue during thermal treatments using a plate heat exchanger (PHE) it directly affects not only energy costs and maintenance but also production, energy and water losses during cleaning operations. Therefore, a considerable attention has been paid to the modelling of the fouling phenomena in order to improve the PHE performances. In this paper, a mathematical model describing the steady state was established for the flow at the macroscopic scale; the model account for constant and turbulent flows between two flat parallel plates at imposed temperature in the presence of a porous medium. The closure k-ε model has been chosen and the conservation of equations has been developed. The numerical procedure adopted was based on the finite volume method on the Fluent CFD software. The accuracy of the Fluent software was validated by comparing our results with those previously published in the literature. The numerical results showed a good reliability of the developed code for both laminar and turbulent regimes of the studied phenomenon. It was able to capture the dynamic and the thermal aspects of the process. The maximum velocity at the output of the channel increased when the thickness of the porous medium was increased. An increase of the average temperature over the whole length of the channel was observed; while a decrease of the average temperature at the outlet of the channel was noticed. The deposit fouling caused additional thermal resistance. Finally, a decrease of the temperature gradient and Nusselt number in the medium of the channel was observed.

In this paper, we examine the effect of a small amount of Sn, Sr and Ca on the hardening and the kinetic properties of Pb. Experimentally, we analyze the specific process from the structural hardening evolution to equilibrium of PbCaSrSn alloy occurring in two steps. In the first one, a discontinuous transformation hardening and a continuous precipitation take place. A lamellar discontinuous precipitation that occurs after aging, characterizes the second step. Theoretically, we study the aging and overaging kinetics of the alloy by using the two complimentary methods needed to calculate the apparent activation energies of the Pb0.058%Ca0.12%Sr1.09%Sn associated with the various transformations, characterizing its hardening at 20 and 80 °C. We show that activation energies of aging and overaging of Pb0.058%Ca0.12%Sr1.09%Sn alloy are 25 and 28 kJ/mole, respectively, which are four times lower than the self-diffusion energy of Pb. Moreover, the addition of Ca, Sr and Sn leads to an amplification of the maximum hardness from 5 ± 5% HV to 21 ± 5% HV and an acceleration of the transformation hardening process responsible for aging.

This study focuses on heat transfer by natural convection in a three dimensional cavity filled with nanoparticles and partially heated from the side with a uniform temperature. The opposite wall of the cavity is maintained in a cold temperature. The effect of nanofluid type on thermal phenomena within the cavity was analyzed for different sizes of the heating section, using the control volume method. The governing parameters are: the Rayleigh number (10³≤Ra ≤ 10⁵), the volume fraction (0 ≤ Φ ≤ 0.1), the heating section size (0.5≤ ≤1), and the nanofluid type. The results represent a great interest in terms of the flow and heat transfer through the cavity depending on the chosen parameters sets.