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In the final stages of production, a pharmaceutical is
Chapter , Problem 8.27(choose chapter or problem)
In the final stages of production, a pharmaceutical is sterilized by heating it from 25 to 75 C as it moves at 0.2 m/s through a straight thin-walled stainless steel tube of 12.7-mm diameter. A uniform heat flux is maintained by an electric resistance heater wrapped around the outer surface of the tube. If the tube is 10 m long, what is the required heat flux? If fluid enters the tube with a fully developed velocity profile and a uniform temperature profile, what is the surface temperature at the tube exit and at a distance of 0.5 m from the entrance? Fluid properties may be approximated as 1000 kg/m3 , cp 4000 J/kg K, m 2 103 kg/sm, k 0.8 W/m K, and Pr 10. 8.2
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QUESTION:
In the final stages of production, a pharmaceutical is sterilized by heating it from 25 to 75 C as it moves at 0.2 m/s through a straight thin-walled stainless steel tube of 12.7-mm diameter. A uniform heat flux is maintained by an electric resistance heater wrapped around the outer surface of the tube. If the tube is 10 m long, what is the required heat flux? If fluid enters the tube with a fully developed velocity profile and a uniform temperature profile, what is the surface temperature at the tube exit and at a distance of 0.5 m from the entrance? Fluid properties may be approximated as 1000 kg/m3 , cp 4000 J/kg K, m 2 103 kg/sm, k 0.8 W/m K, and Pr 10. 8.2
ANSWER:Heat Flux:
Q = (mc*?T)/L
Q = (1000 kg/m3*4000 J/kg*50 K)/10 m
= 2*10^6 J/m^2