RETARDATION OF A HEAT FRONT IN A POROUS
MEDIUM CONTAINING AN EVAPORATING LIQUID
Yu. Yu. Tanashev, V. N. Parmon, and
Yu. I. Aristov

UDC 536.24;536.37

We have investigated heat transfer in a layer of silica 
gel impregnated with a liquid (water, aqueous solutions of calcium 
and magnesium chlorides, formic acid, and carbon tetrachloride). The 
layer was arranged on a substrate impenetrable for vapor and it was 
heated from above by a concentrated light flux. It has been found 
that the evaporation of the liquid contained in the pores of silica 
gel substantially slows down the propagation of the heat front into 
the layer so that the effective thermal conductivity of the layer 
can be reduced to 0.01 W/(m x K); this value is approximately 
4-20 times smaller than the values typical of the majority of 
standard heat-insulating materials. The time of the front lag depends 
on the layer thickness, density of the incident heat flux, amount 
of liquid in the pores, and evaporation heat of the liquid. The observed 
trends in the motion of the front have been described by a simple 
one-dimensional model that takes into account phase transition (liquid 
evaporation) in the interior of the porous matrix.

G. K. Boreskov Institute of Catalysis, Siberian Branch 
of the Russian Academy of Sciences, Novosibirsk, Russia; email: tanashev@catalysis.nsk.su.
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 74, No. 5, 
pp. 3-6, September-October, 2001.
Original article submitted January 15, 2001.

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