A. Conduction
B. Radiation
C. Natural convection
D. Forced convection
Related Mcqs:
- One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m-1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is____________________?
A. 100
B. 900
C. 9000
D. 10000 - Heating the Hypo-eutectoid steels to 30°C above the upper critical temperature line, soaking at that temperature and then cooling slowly to the room temperature to form a pearlite & ferrite structure is called_______________________?
A. Tempering
B. Hardening
C. Annealing
D. Normalising - Heat transfer to the water wall in a high pressure water wall type boiler furnace is mainly by_________________?
A. Conduction
B. Convection
C. Radiation
D. Both A. & B. - Heating of ferromagnetic materials to a temperature above Curie temperature makes it ________________________?
A. Insulator for heat & electricity transmission
B. Ferritic
C. Behave like paramagnetic materials
D. Superconductor - A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness ______________ metre?
A. 0.01
B. 0.1
C. 0.25
D. 0.5 - For the irreversible reaction, Ca+ 2C = Ca C2 , Δ H°298 = – 60000 J . mole-1 . If a system initially containing 2 moles of calcium, 3 moles of carbon and 1 mole of calcium carbide is allowed to react to completion, the heat evolved at 298 K will be__________________?
A. 30,000 J
B. 60,000 J
C. 90,000 J
D. 2,40,000 J - ______________ wire is never used for making the heating element ?
A. Nichrome
B. Kanthal
C. Invar
D. None of these - A thin, flat & square plate measuring 2 m × 2 m is freely hanging in ambient air at 25°C. It is exposed to the solar radiation falling on one side of the plate at the rate of 500 W/m2. The plate temperature will remain constant at 30°C, if the convective heat transfer co-efficient is ________________ W/m2 °C ?
A. 50
B. 100
C. 150
D. 200 - Electrolytic reduction cell used for conversion of calcined Al2O3 to Al is a carbon lined furnace operating at 800-900 °C. The purpose of electric current supplied to the furnace is to___________________?
A. Achieve very high purity of aluminium (99.9%)
B. Keep the electrolyte in liquid condition by the generation of heat
C. Electrolytically dissociate alumina
D. Both B. & C. - Transformation range for ferrous material is the temperature interval during which ___________________ is formed during its heating?
A. Cementite
B. Austenite
C. Martensite
D. Pearlite
