Exercise 3
A 2-cm diameter tube is maintained at constant wall temperature of 90\deg C. Water enters the tube at 40\deg C
and leaves at 60\deg C. If the entering velocity is 3(m)/(s). calculate the length of tube necessary to accomplish the
heating.
Hint : Take the average temperature of the water T_(water )=(40+60)/(2)=50\deg C.
The fluide properties at T_(m)=(90+50)/(2)=70\deg C are
Pr=2.54,\mu =4\times 10^(-4)k(g)/(m).s,k=0.664(W)/(m).\deg C,C_(p)=4.174k(J)/(k)g.\deg C,\rho =978k(g)/(m^(3))