question archive Four power transistors of 20cm × 20cm each, dissipating 48W in total (12W each), are mounted in line on a well-insulated surface at the bottom
Four power transistors of 20cm × 20cm each, dissipating 48W in total (12W each), are mounted in line on a well-insulated surface at the bottom
Subject:Mechanical EngineeringPrice: Bought3
Four power transistors of 20cm × 20cm each, dissipating 48W in total (12W each), are mounted in line on a well-insulated surface at the bottom. The space between one transistor and another can be despised. All heat is dissipated to an air flow at 22 m/s, with a temperature of 20ºC, parallel to the transistors. The rate of heat dissipation can be considered constant throughout the row of transistors. Consider air properties constant and equal to ρ = 1, 204kg/m3, cp = 1007J/kg ·K, ?k? = 0, 02514W/m·K, ?v? = 1, 516 × 10−5m2/s, Pr = 0, 7309 (Prandtl number)
Under these conditions, answer the following items.
a) In which transistor is the maximum temperature? Justify your answer.
b)What is the maximum temperature value?
c) Now consider that the first transistor has been damaged, has stopped working and no longer dissipates heat.
Determine the maximum temperature value and at which transistor it occurs, in this new situation.
