A printed circuit board with constant surface temperature dissipates 100 W from one side over an area (0.3 mx 0.2 m). A fan is use to cool this board with a flow speed of 12 m/s parallel to the longest dimension of the board. Calculate: 1. The surface temperature of the board for an air temperature of 30 C. 2. Thickness of hydrodynamic and thermal boundary layer. 3. Amount of change in heat transfer rate if the flow parallel to the short dimension. Cp-1000 J/kg.K, k-0.03 W/m.C, Pr-0.667, u = 2 x 105 kg/m.s, p=1.15 kg/m³ Laminar flow, Nu-0.664Rel/2Pr1/3 Turbule flow, Nu= 0.037Re4/5r1/3 "

A printed circuit board with constant surface temperature dissipates 100 W from one side over an area (0.3 mx 0.2 m). A fan is use to cool this board with a flow speed of 12 m/s parallel to the longest dimension of the board. Calculate: 1. The surface temperature of the board for an air temperature of 30 C. 2. Thickness of hydrodynamic and thermal boundary layer. 3. Amount of change in heat transfer rate if the flow parallel to the short dimension. Cp-1000 J/kg.K, k-0.03 W/m.C, Pr-0.667, u = 2 x 105 kg/m.s, p=1.15 kg/m³ Laminar flow, Nu-0.664Rel/2Pr1/3 Turbule flow, Nu= 0.037Re4/5r1/3 "

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.

Chapter5: Analysis Of Convection Heat Transfer

Section: Chapter Questions

Problem 5.50P

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