# Chapter 10 : Heat transfer in condensing and boiling¶

## Example 10.1 page : 206¶

In [2]:
# Variables
y = 1.9;                                      # Density in slug/ft**-2
u = 0.0354;                                   # Vismath.cosity in slug/ft-hr
k = 0.376;                                    # Thermal conductivity in Btu/hr-ft-degF
l = 32600.;                                    # Heat of condensation in Btu/slug
Tg = 142.;                                     # Temperature of steam in degF
Tw = 138.;                                     # Temperature of wall in degF

# Calculations
delT = Tg-Tw;                                 # Temperature driving force in degF
g = 418*10**6;                                 # Gravity in ft/sec**2
L = 1./12;                                     # Outside diameter of horizontal tube in ft
C = 0.725;                                    # For horizontal tube
h = C*(g*y**2*l*k**3/(L*u*delT))**0.25;          # Heat transfer coefficient in Btu/hr-ft**2-degF

# Results
print "The heat transfer coefficient for steam condensing on a horizontal tube is %d Btu/hr-ft**2-degF"%(h);

# note: rounding off error.

The heat transfer coefficient for steam condensing on a horizontal tube is 2797 Btu/hr-ft**2-degF