HEAT AND MASS TRANSFER

HEAT TRANSFER BY CONDUCTION

Fouriers law of conduction

Q is proportional to area perpendicular to heat flow
and is directly proportional to temperature differential dT
and inversely proportional to thickness dx

there fore fouriers law of heat conduction is
Q =kAdT / dx
k= thermal conductivity of material


                  conduction by.....

   free electrons   : contribute to thermal conduction

   lattice vibration produce lattice wave

     variation of thermal conductivity of material with temperature 

For solids in general the variation is shown in graph

For liquids and gases  the variation in general is as follows

In liquids and gases conduction occur due to molecular collisions