Environmental Engineering Reference
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If there is no laminar stream, then a free convection occurs. On the contrary, a
forced convective regime is established in the porous medium by the action of the
continuous injection of air stream. The stream orientation is modified in the zones
close to the punctual heated source. Consequently, the temperature distribution will
be changed resulting in a new plume configuration. The model studied by Kurdyu-
mov and Liñán (
2001
) predicts the behavior of the two-dimensional velocity field of
an air stream around the heated source, as well as its relationship with the tempera-
ture gradients that conform the buoyant plumes under the action of free and forced
convection.
In the first stage of this work, the pure free convection case is reproduced experi-
mentally, analyzed and compared to the theoretical solutions obtained byKurdyumov
and Liñán (
2001
), and in a second part the effects of the forced convection are stud-
ied, and the buoyant plumes are obtained by varying the direction of the induced
streams.
3 Experimental Setup
Despite the fact that the theory was made for an infinite medium, in the present
experiments we have used a cardboard box (parallelepiped) of 0.28m height, 0.20m
length and 0.1m depth, which was filled with Ottawa sand (ASTM C778), building
a non consolidated homogeneous porous matrix. At the middle of the box a cylin-
drical resistance of 0.00959m diameter was embedded. To supply a continuous air
rate, a compressor 1.2MPa was used together with flow aligners to induce a uniform
air stream. In order to sense the resistance temperature a type T thermocouple was
placed at the rear end of it and was connected to a WEST (6100
) process indi-
cator for the temperature control. For all the tests, the resistance reaches 353.15K.
+
Fig. 2
Scheme of the experimental array
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