Chapter 1, Problem 1.66P

In a glass plant in Cavite, a furnace has fire-brick walls made up of the following two materials in series :                        Non-corrosive brick as inner layer (material 1) Clay brick as outer layer (material 2) Thickness 4.5 inches 8 inches Thermal conductivity k1 k2   The temperature inside the furnace (inside wall surface of the non-corrosive brick) is found to be 1105 oF while the outside temperature (outside wall surface of clay brick) is 365 oF.   This is not the desired temperature inside the furnace so engineers thought of lagging the furnace walls with another material to reduce heat loss.  The additional lagging material consists of magnesia layer which is 2 inches thick and has a thermal conductivity of 0.04 Btu /h.ft.oF.   During a test run on the furnace with the magnesia lagging material now,  new temperature readings were recorded : Point of measurement Temperature reading Inside furnace (inside wall surface of non-corrosive brick      1355 oF Interface between…

Question 5: Z=62 a. An iron sphere of mass (Z + 300)g is kept in a container having boiling water (100 °C). If the temperature of the sphere is 25.5°C, how much heat energy is absorbed by the iron sphere? Consider the specific heat of iron as 452J/kg. b. The wall of an industrial furnace is constructed from (Z + 3) cm thick fireclay brick having a thermal conductivity of 1.7 W/mK. Measurements made during steady-state operation reveal temperatures of 530°C and 375°C at the inner and outer surfaces, respectively. Find the rate of heat loss through a wall which is (Z + 5) cm by (Z + 3) m on a side.

ösly äbä With rise in temperature , the conductivity of the metals depending on temperature remains constant decreases Increases نقطة واحدة When heat is transferred from hot body to cold body, in a straight line, without affecting the intervening medium, it is referred as heat transfer by conduction and convection radiation conduction convection نقطة واحدة Thermal diffusivity of a : substance is