Related Questions

Which one of the following equations most directly determines the power dissipation of a resistance when you know the power dissipation of a resistance when you know the voltage drop and current?
A P = IE
B P = E2/R
C P = I2R
D I = P/E
E None of the above
The heated parts of an electrical machine dissipate heat into their surroundings by which of the followingmodes of heat dissipation ?
A Conduction
B Convection
C Radiation
D All of the above
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
Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is
A Finned tube heat exchanger with air inside and steam outside
B Finned tube heat exchanger with air outside and steam inside
C Shell and tube heat exchanger with air inside tubes and steam on shell side
D Shell and tube heat exchanger with air on shell side and steam inside tubes
Heat dissipation in cooling towers is mainly by
A Conduction
B Convection
C Evaporation
D Radiation
With increase in the distance between the heat source and the object receiving the heat, the radiation heat transfer
A Decreases
B Increases
C Increases exponentially
D Remains unaffected
How are the efficiencies of any heat engine (miu) and reversible heat engine (miuR) compared, when both are operating between same heat source and same heat sink?
A miu = miuR
B miu>miuR
C miu
D none of these
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
A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of
A 2
B 20.8
C 20.2
D 20.5
Noise produced by cooling fans (employed in air cooled heat exchangers or cooling tower) is mainly caused due to the turbulence created by blade passage through air. It can be reduced by use of a slower fan
A With greater number of blades
B Of increased diameter
C Both A & B
D Neither A nor B

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