A cryogenic fluid is stored in a 0.3-m-diameter spherical container in still air. If the convection heat transfer coefficient between the outer surface of the container and the air is 6.8 W/(m2 K), the temperature of the air is 27°C and the temperature of the surface of the sphere is –183°C, determine the rate of heat transfer by convection.
GIVEN
• A sphere in still air
• Sphere diameter (D) = 0.3 m
• Convective heat transfer coefficient ch = 6.8 W/(m2K)
• Sphere surface temperature (Ts) = –183°C
• Ambient air temperature (T?) = 27°C
FIND
• Rate of heat transfer by convection (qc)
ASSUMPTIONS
• Steady state heat flow
SKETCH
The rate of heat transfer by convection is given by
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