{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

hw05soln

# hw05soln - 1 A furnace of cubical shape with external...

This preview shows pages 1–2. Sign up to view the full content.

1. A furnace of cubical shape with external dimensions of 0.35 m is constructed from a refractory brick having thermal conductivity k=1.15 W/m•K. If the wall thickness is 50 mm, the inner surface temperature is 600°C, and the outer surface temperature is 75°C, calculate the heat loss from the furnace. 0.35 m 0.05 m L Plane wall 25 . 1 05 . 0 ) 25 . 0 )( 25 . 0 ( L A S W = = = m Edge 135 . 0 ) 25 . 0 )( 54 . 0 ( L 54 . 0 S E = = = m Corner 0075 . 0 ) 05 . 0 )( 15 . 0 ( t 15 . 0 S C = = = m ) T T )( S 8 S 12 S 6 ( k ) T T ( kS q 2 1 C E W 2 1 - + + = - = = ) 75 600 )( 0075 . 0 8 135 . 0 12 ) 25 . 1 6 )( 15 . 1 ( - × + × + × =5.5 kW 2. A solid having volume V, surface area A s , and thermal conductivity k is exposed to a fluid with convective heat transfer coefficient h and ambient temperature T . For Biot number Bi<<1, (a) The solid’s spatial temperature distribution is uniform (isothermal) at each instant in time. Why??? (b) For an initial solid temperature T i , derive the temperature in the solid as a function of time and the total heat transfer rate. (a) The temperature gradient in the solid is small compared to the fluid. Relative to

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}