Exercise -3

In this and some other problems, the dimensions of physical constants are expressed in FPS system, so that the readers have a feel about the order of magnitude of the values in the above system.

a)  A vertical furnace wall is constructed of silica brick, with a total area of 400 sq ft and thickness of 15 inches. The furnace temperature is  and that of surrounding . Calculate (i) heat loss through this wall, Btu/ hr, (ii) fuel oil consumption equivalent to heat loss, liters/day, for a fuel oil which furnishes 11360 Btu/liter of available heat to the furnace chamber, and (iii) the thickness of silica brick

b) K exposed to temperature  

c) Addition of a 3-inch layer of insulating material (K=0.12) to the furnace wall is being considered. Calculate (i) the percentage reduction in heat loss which should be attained by adding the insulation, (ii) the daily fuel saving, if the fuel oil costs Rs. 50/litre, and (iii) the thickness of silica brick   exposed to  after adding insulation.