A. Andreozzi et O. Manca, Thermal and fluid dynamic behavior of symmetrically heated vertical channels with auxiliary plate, INT J HEA F, 22(4), 2001, pp. 424-432
Air natural convection in vertical channel configurations is strongly attra
ctive in thermal design and control of devices. This is mainly due to its s
implicity, no maintenance costs and reliability. This paper examines air na
tural convection in vertical channels with an auxiliary plate along the cen
terline. The channel is symmetrically heated and the walls are at uniform h
eat flux, whereas the auxiliary plate is either adiabatic or heated at unif
orm heat flux. The analysis is obtained for a two-dimensional steady state
and laminar regime, and the fully elliptic equations are solved numerically
by the control volume method on a finite I-shaped computational domain. Re
sults in terms of stream function and temperature fields, velocity and temp
erature profiles inside the channel and pressure profiles along the centerl
ine are given either for insulated auxiliary plate or for heated auxiliary
plate. The adiabatic auxiliary plate along the centerline of the channel pr
oduces a chimney effect reduction of the channel while the heated auxiliary
plate, at higher Ra values (10(5)-10(6)), provides an increase in the mass
flow rate in the channel. Finally, two correlations between average channe
l Nusselt number, channel Rayleigh number, Ra*, and dimensionless auxiliary
plate height, h/L, are proposed. One correlation is for the channel with h
eated auxiliary plate and another is for the channel with unheated auxiliar
y plate. The channel Rayleigh number range is 10(2)-10(5) and the dimension
less auxiliary plate height, h/L, is in the range [0, 1]. (C) 2001 Elsevier
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