Abstract
The objective of this work is to study the effect of the thickness of a porous separation on the thermal performance in a cavity with displacement ventilation. The cold air jet enters and exits through two openings located in the lower and upper parts of the left wall and the right wall respectively. The other horizontal walls are also adiabatic. The hydrodynamic and thermal characteristics of the transfer were studied for three configurations with the same aspect ratio L/H=2. The height Hp of the porous separation was varied between 0.2 and 0.8 where is placed in the center of the cavity. The transfer rates on the active wall for the thicknesses were studied for different permeability therefore different Darcy numbers varying over an interval:10-6≤Da≤10. The dimensionless Rayleigh and Reynolds numbers were taken from the rows: 10≤Ra≤106 and 50≤Re≤500. The governing equations of momentum and energy were solved by the Lettice Boltzmann Multiple Relaxation Time Method (LB-MRT) D2Q9 for the velocity field and D2Q5 for the temperature field. In order to take into account the introduction of the porous medium, an additional term is added to the standard LB equations based on the generalized model (Darcy model extended to Brinkman-Forchheimer).
Highlights
The study of displacement ventilation (DV) in rectangular enclosure is of interest in a wide range of civil and industrial applications [1], such as chemical applications, thermal and pollution control [2, 3], and building applications [4,5,6,7]
Note that in displacement ventilation air supply diffusers are located near Àoor level and the outdoor air velocity is very low compared with the first mode (i.e. mixing ventilation (MV)), and exhausted air is extracted from the ceiling level by buoyancy forces
The review of the literature indicates that the displacement ventilation heat transfer in enclosure has been addressed in many of previous research; there are only few researches which have considered porous obstacles inside the cavity, and no studies do undertake into account a vertical porous partition
Summary
The study of displacement ventilation (DV) in rectangular enclosure is of interest in a wide range of civil and industrial applications [1], such as chemical applications, thermal and pollution control [2, 3], and building applications [4,5,6,7]. The review of the literature indicates that the displacement ventilation heat transfer in enclosure has been addressed in many of previous research; there are only few researches which have considered porous obstacles inside the cavity, and no studies do undertake into account a vertical porous partition. This model could represent the process of heat removal by displacement ventilation in rectangular enclosure such as: large room, open space office, or general ward of hospital
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