9. Fin efficiency is defined as: tanh (mL) (hP/k Ac)1/2 (heat transfer with fin) / (heat transfer without fin) (actual heat transfer through fin) / (heat transfer assuming all fin is at T = Tb) (Tx=L-Tf)/(Tb-Tf) 10. For an infinite fin, the temperature distribution is given by: (T-Tf)/(Tb-Tf)=e-mx. The heat flow through the fin is therefore given by: k (Tb-Tf)/L zero, because the fin is infinite infinite because the fin is infinite (Tb-Tf) (h P/k Ac)1/2 (Tb – Tf) (h_P/ k Ac)1/2 tanh (mL) 11. The Biot number, Bi, is defined as: • Bi=hk/L • Bi=hL/k • Bi= k/LH • Bi=qL/k • Bi=p UL/k 12. For a plate of length L, thickness, t, and width, W, subjected to convection on the two faces of area L x W. What is the correct length scale for use in the Biot number? L . W . t/2 • L/2 13. If Bi << 1, then this implies: heat transfer is negligible the surface is insulated conduction is time dependent temperature variations within the solid are negligible temperature variations within the solid are significant

9. Fin efficiency is defined as: tanh (mL) (hP/k Ac)1/2 (heat transfer with fin) / (heat transfer without fin) (actual heat transfer through fin) / (heat transfer assuming all fin is at T = Tb) (Tx=L-Tf)/(Tb-Tf) 10. For an infinite fin, the temperature distribution is given by: (T-Tf)/(Tb-Tf)=e-mx. The heat flow through the fin is therefore given by: k (Tb-Tf)/L zero, because the fin is infinite infinite because the fin is infinite (Tb-Tf) (h P/k Ac)1/2 (Tb – Tf) (h_P/ k Ac)1/2 tanh (mL) 11. The Biot number, Bi, is defined as: • Bi=hk/L • Bi=hL/k • Bi= k/LH • Bi=qL/k • Bi=p UL/k 12. For a plate of length L, thickness, t, and width, W, subjected to convection on the two faces of area L x W. What is the correct length scale for use in the Biot number? L . W . t/2 • L/2 13. If Bi << 1, then this implies: heat transfer is negligible the surface is insulated conduction is time dependent temperature variations within the solid are negligible temperature variations within the solid are significant

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.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.21P

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