Answer to Question #107903 in Physics for rizka fernanda

Question

A cube of a car transmission cube of w is equal to 0.3 m, receiving 150 Horsepower from an engine (1cell =746 w). If the transmission efficiency is 0.93, and the air surrounding temperature is 30°C, and h= 200w/m2K. Calculate surface temperature of the transmission box, if the radiation is not calculated

Answer 1

From Newton’s law of cooling,

$q=hA_s=(T_s-T_\infty)=6hW^2(T_s-T_\infty)$

The heat rate is

$q=P_i-P_o=P_i(1-\eta)=()()()=7833\ W$

Thus,

$T_s=T_\infty+\frac{q}{6hW^2}=30+\frac{7833}{6(200)(0.3)^2}=102.5\degree C$