# Chapter 14 : Heat transfer in temperature measurements¶

## Example 14.1 page : 233¶

In :
# 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);

The temperature of gas is 1113 degF