# Variables
D1 = 36./12; # diameter of circular duct in ft
D2 = 5./96; # diameter of tube in ft
Tl = 800.; # Temperature of tube in degF
To = 500.; # Temperature of duct in degF
k = 0.02; # Thermal conductivity in lb/ft**-2-hr
u = 0.18*(10**-9)*(3600**2); # Vismath.cosity in slug/ft-hr
p = 0.04/32.2; # Density in slug/ft**3
n = u/p; # Kinematic vismath.cosity in ft**2/hr
v = 15.*3600; # Velocity in ft/hr
e = 0.8; # Emmisivity
# Calculations
Nre = v*D2/n; # Reynolds number
Nnu = 0.3*(Nre**0.57); # Nusselt number
h = Nnu*k/D2; # Heat transfer coefficient
Tg = Tl+0.174*e*((((Tl+460)/100)**4)-((To+460)/100)**4)/h; # Gas temperature in degF
# Results
print "The temperature of gas is %.f degF"%(Tg);