J. Bonjour et M. Lallemand, EFFECTS OF CONFINEMENT AND PRESSURE ON CRITICAL HEAT-FLUX DURING NATURAL CONVECTIVE BOILING IN VERTICAL CHANNELS, International communications in heat and mass transfer, 24(2), 1997, pp. 191-200
An experimental study has been carried out for the critical heat flux
(CHF) during the natural convective boiling of R-113 at various pressu
res in a vertical channel. The pressure ranges from 1 to 3 bar and the
channel gap-size from 0.3 mm to 2.5 mm as its height is kept constant
. Data for pool boiling are also obtained. At all pressures investigat
ed, the CHF decreases as the gap-size is reduced. On the other hand, f
or this pressure range, an increase in CHF is observed with increasing
pressure. Nevertheless, one has to notice that this last trend is not
so pronounced for narrow as for wide channels. The effect of pressure
cannot compensate the decrease in CHF due to the channel gap-size red
uction. A previously published correlation for the CHF in such systems
is modified so as to take into account the influence of pressure. It
is in good agreement with the experimental data since its accuracy is
always better than 5 %. (C) 1997 Elsevier Science Ltd.