Related Questions

A _________ in a boiler is used to put off fire in the furnace of the boiler when the level of water in the boiler falls to an unsafe limit.
A Blow off cock
B Fusible plug
C Stop valve
D Safety valve
The scales form in heat exchanges after a period of operation and provide additional resistance to heat transfer with some heat transfer coefficient . The reciprocal of this scale heat transfer coefficient is called .
A scaling factor
B forming factor
C resisting factor
D fouling factor
Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the
A Surrounding temperature
B Average temperature of the fin
C Temperature of the fin end
D Constant temperature equal to that of the base
Heat transfer to the water wall in a high pressure water wall type boiler furnace is mainly by
A Conduction
B Convection
C Both A & B
D Radiation
In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by
A Convection
B Radiation
C Conduction
D Both convection and conduction
In water wall furnace, the heat is transferred to the water walls by
A Convection
B Radiation
C Conduction
D Radiation and conduction
Ceramic coating material for furnace refractory, which increases its emissivity and thus the radiation heat transfer rate in the furnace, comprises of
A Graphite powder
B Thoria
C Zircon powder
D Beryllium
A device used to put off fire in the furnace of the boiler when the level of water in the boiler falls to an unsafe limit, is called
A Blow off cock
B Stop valve
C Superheater
D None of these
Design of waste heat boiler for recovery of waste heat from furnace gases depends upon the
A Quantity & temperature of waste gas
B Dust concentration & nature of dust in waste gas
C Corrosive nature of the waste gas
D All of the above
The electric furnace in which heat is produced by a combination of induced current and skin effect is called __________ furnace.
A Arc
B Resistance
C Low frequency induction
D High frequency induction

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