Conduction is heat transfer by means of molecular agitation within a material without any motion of the material as a whole. If one end of a metal rod is at a higher temperature, then energy will be transferred down the rod toward the colder end because the higher speed particles will collide with the slower ones with a net transfer of energy to the slower ones. For heat transfer between two plane surface, such as heat loss through the wall of a house, the rate of conduction heat transfer is:

Calculation

Q= heat transferred in time =t
K= thermal conductivity of the barrier
A= area
T= temperature
d= thickness of barrier

 

Table Showing Various values for k at 20oC, k = Thermal conductivity (W/mK)

Metalk=Wm-1K-1
Aluminium237
Antimony18.5
Beryllium218
Brass110
Cadmium92
Cobalt69
Constantan22
Copper398
Gold315
Iridium147
Cast Iron55
Pure Iron80.3
Wr't Iron59
Lead35.2
Magnesium156
Molybdenum138
Monel26
Nickel90.5
Platinum73
Silver427
Carbon Steel50
Stainless Steel25
Tin67
Zinc113
Plastics
Acrylic0.2
Nylon 60.25;
Polythene High Den0.5
PTFE0.25
PVC0.19