A reduction in thermal resistance during heat transfer does not occur in the

A Convection heat transfer by stirring the fluid and cleaning the heating surface
B Conduction heat transfer by reduction in the material thickness and increase in the thermal conductivity
C Radiation heat transfer by increasing the temperature and reducing the emis-sivity
D None of these

Correct Answer: Radiation heat transfer by increasing the temperature and reducing the emis-sivity

Bissoy MCQ
#Chemical Engineering #Chemical Engineering Basics

Related Questions

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
Controlling heat transfer film co-efficient is the one, which offers __________ resistance to heat transfer.
A No
B The least
C The largest
D Lower
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
Overall thermal resistance for conductive heat transfer through a series of flat resistances is equal to the
A Maximum resistance in the series
B Sum of all resistances
C Average of all resistances
D Minimum resistance presents in the series
Thermal conductivity based continuous flue gas analyser makes use of varying thermal conductivity of the constituents of flue gases. Which of the following constituents of flue gases has the maximum thermal conductivity?
A CO2
B N2
C O2
D CO
Which of the following would lead to a reduction in thermal resistance?
A In conduction, reduction in the thickness of the material and an increase in thermal conductivity.
B In convection, stirring of the fluid and cleaning the heating surface.
C In radiation, increasing the temperature and reducing the emissivity.
D All of the above
The overall resistance for heat transfer through a series of flat resistance, is the __________ of the resistances.
A Average
B Geometric mean
C Product
D Sum
If a heat transfer surface is pock-marked with a number of cavities, then as compared to a smooth surface the heat transfer by __________ will not increase.
A Convection
B Nucleate boiling
C Radiation
D Conduction

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