A surface is to be kept at 20 °C (68 °F) with a fixed heat flux of 500 W/m2 , determine the driving force (ΔT in °C and Ts °F) required to maintain this surface temperature for the following cases (assuming heat transfer only by the specified mechanism and that the system is at steady state) use Incropera to find thermal conductivities: a) Conduction through 10cm of plain carbon steel. b) Conduction through 4 inches of fully baked cake. c) Free convection through air (h = 18 W/m2 .K). d) Free convection through water (h = 600 W/m2 .K). e) Forced convection through air (h = 200 W/m2 .K). f) Forced convection through a water (h = 14,000 W/m2 .K). g) Radiation from a blackbody (assuming a grey surface). h) Radiation from a grey surface with an absorptivity of 0.36. i) Given the above calculations, comment on why older models of the Volkswagon Beetle having a fan cooled engine instead of a conventional radiator were sometimes nicknamed a “Firebug”.
Heat Transfer question
Heat transfer
W/m2
, determine the driving force (ΔT in °C and Ts °F) required to maintain this surface temperature for the
following cases (assuming heat transfer only by the specified mechanism and that the system is at steady state)
use Incropera to find thermal conductivities:
a) Conduction through 10cm of plain carbon steel.
b) Conduction through 4 inches of fully baked cake.
c) Free convection through air (h = 18 W/m2
.K).
d) Free convection through water (h = 600 W/m2
.K).
e) Forced convection through air (h = 200 W/m2
.K).
f) Forced convection through a water (h = 14,000 W/m2
.K).
g) Radiation from a blackbody (assuming a grey surface).
h) Radiation from a grey surface with an absorptivity of 0.36.
i) Given the above calculations, comment on why older models of the Volkswagon Beetle having a fan
cooled engine instead of a conventional radiator were sometimes nicknamed a “Firebug”.
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