Numerical Example - continued.

Heat Required in Phase 2

Latent Heat Added = (Latent Heat of Vaporization) x Mass

In our case we have the following:

Latent heat of vaporization for water is 970 BTU per pound

Mass = 1 lb.

Therefore, Latent Heat Added = 970 x 1 = 970 BTU

Now we can add the heat used in the two phases:

Total heat required = 142 + 970 = 1112 BTUs