A uniform brick wall separates the inside of a cold storage room from the outside…
PHYSICS · Multi-part · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
A uniform brick wall separates the inside of a cold storage room from the outside atmosphere. The inner face of the wall is kept at −5∘C while the outer face remains at 25∘C in steady state. Answer the following questions related to the transfer of heat through the wall:
(a) State the mathematical relation connecting the rate of heat flow through a uniform slab with its cross-sectional area, thickness, temperature difference across it, and the material characteristic involved.
(b) Using the relation stated in part (i), explain qualitatively how the rate of heat flow will change if the thickness of the wall is doubled while all other quantities remain the same.
(c) Give two distinct reasons, based on heat conduction principles, for preferring thick walls made of materials having low numerical values of the characteristic mentioned in part (i) in cold storage construction.