Related Questions

In spite of large heat transfer co-efficients in boiling liquids, fins are used advantageously, where the entire surface is exposed to __________ boiling.
A Film
B Nucleate
C Transition
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
The equivalent diameter for the annulus of a double pipe heat exchanger, whose inner pipe has fins on the outside is __________ compared to the same size pipes without fins.
A More
B Less
C Same
D Unpredictable
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
In which of the following cases provision of fins on a given heat transfer surface will be more effective?
A Fewer but thin fins
B Large number of thin fins
C Large number of thick fins
D Fewer but thick fins
The main purpose of providing fins on heat transfer surface is to increase the
A Temperature gradient
B Mechanical strength of the equipment
C Heat transfer area
D Heat transfer co-efficient
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
The distillation carried out in such a way that the liquid with the lowest boiling point is first evaporated and re-condensed, then the liquid with the next higher boiling point is then evaporated and re-condensed, and so on until all the available liquid fuels are separately recovered in the sequence of their boiling points. Such a process is called
A Cracking
B Fractional distillation
C Full distillation
D Carbonisation
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

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