Related Questions

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
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 in liquid and gases takes place by
A Conduction
B Convection
C Radiation
D Conduction and convection
In case of non-ideal gases and liquids, the molal diffusivity
A Varies inversely as the pressure
B Varies directly as the pressure
C Is independent of pressure
D Is equal to the volumetric diffusivity
For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area
A Increases
B Decreases
C Remains constant
D Passes through a maxima
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
The concept of overall coefficient of heat transfer is used in case of heat transfer by
A Conduction
B Convection
C Radiation
D Conduction and convection
In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate.
A Geometric
B Arithmetic
C Logarithmic
D Either A, B or C
In regenerator type heat exchanger, heat transfer takes place by
A Direct mixing of hot and cold fluids
B A complete separation between hot and cold fluids
C Flow of hot and cold fluids alternately over a surface
D Generation of heat again and again

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