t = 30 + 0.9563 (62.2- 30) = 60.79°C (Ans.)Example 4.14. A very thin glass walled 3 mm diameter mercury thermometer is placed in astream of air, where heat transfer coefficient is 55 W/m2°C, for measuring the unsteady temperatureof air. Consider cylindrical thermometer bulb to consist of mercury only for which kand a = 0.0166 m2/h. Calculate the time required for the temperature change to reach half its finalor,%3D8.8 W/m C%3Dvalue.

Answered: Image /qna-images/answer/cd738faf-b362-434f-9403-b3a78493b4a1.jpg

Answered: and a = 0.0166 m-/h. Calculate the time…

Engineering

Mechanical Engineering

and a = 0.0166 m-/h. Calculate the time required for the temperature change to reach half its final value.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter5: Analysis Of Convection Heat Transfer

Section: Chapter Questions

Problem 5.22P

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Concept explainers

Work and Heat Transfer

It is generally related to thermal engineering which tells about the use, creation, conversion and transfer of heat energy between the systems. It is also considered that to transfer heat from one source to another, transfer of masses is also required. There are various mechanisms by which, transfer of heat takes place i.e. thermal conduction, convection, radiation or by change of phase. All these mechanisms have their own specific features which sometimes occur simultaneously within the same system.

Question

t = 30 + 0.9563 (62.2- 30) = 60.79°C (Ans.)
Example 4.14. A very thin glass walled 3 mm diameter mercury thermometer is placed in a
stream of air, where heat transfer coefficient is 55 W/m2°C, for measuring the unsteady temperature
of air. Consider cylindrical thermometer bulb to consist of mercury only for which k
and a = 0.0166 m2/h. Calculate the time required for the temperature change to reach half its final
or,
%3D
8.8 W/m C
%3D
value.

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