Test: Fourier Equation - Mechanical Engineering MCQ

He gave this theory in 1824.

According to Fourier law of heat conduction, Q = -k A d t /d x.

It has constant temperature gradient and a linear temperature profile.

Thermal conductivity is different for different materials.

Heat conducted through the plate = convection heat losses + radiation heat losses. So, d t /d x = – 13155/12.5 = – 1052.4 degree Celsius.

The ratio d t/d x represents the change in temperature per unit thickness i.e. the temperature gradient. So it represents heat flow in the direction of negative temperature gradient.

In gases atoms are arranged loosely, there is less molecular transmission of heat as compared to solids, liquids and alloys.

The unit kcal/m hr K could also be specified as J/m s K or W/m s K and this is actually done while quoting the numerical values of thermal conductivity.

 It is across unit area and through unit distance.

Thermal resistance is expressed in the unit’s hr degree/kcal, degree/W and s degree/J.