Related Questions

Which of the following plays an important role in problems of simultaneous heat and mass transfer?
A Lewis number
B Schmidt number
C Prandtl number
D Sherwood number
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
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
The concept of overall coefficient of heat transfer is used in heat transfer problems of
A Conduction
B Convection
C Radiation
D Conduction and convection
Sohana's mathematics test had 75 problems i.e. 10 arithmetic, 30 algebra and 35 geometry problems each carrying I mark She answered 70% of the arithmetic, 40% of the algebra and 60% of the geometry problems correctly. She did not pass the test as she got less than 60% marks. How many more questions she would have needed to answer correctly to earn a 60% passing grade?
A 5
B 10
C 15
D 20
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
Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the __________ number.
A Sherwood
B Schmidt
C Peclet
D Stanton
Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the __________ number.
A Schmidt
B Sherwood
C Peclet
D Stanton
If mass diffusivity in a mixture is equal to the thermal diffusivity, then the Lewis number is
A 0
B 1
C > 1

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