We notice from the development in Section a) that the equations
relating relative and specific humidity, temperature (wet and
dry bulb), pressure (air, vapor) and enthalpy are quite tedious
and inconvenient. For this reason a Psychrometric Chart relating
all the relevant variables was developed which is extremely
useful for designing and evaluating air-conditioning and cooling
tower systems. At first appearence the psychrometric chart is
quite confusing, however with some practice it becomes an
extremely useful tool for rapidly evaluating air-conditioning
processes. The most popular chart in common usage is that
developed by ASHRAE (American Society of Heating, Refrigeration
and Air-Conditioning Engineers), however we feel that the
construction of a simplified version of the chart based on
approximations of the various equations can be a very useful
tool for developing an understanding of it's usage. This
approach was suggested by Maged El-Shaarawi in his article "On
the Psychrometric Chart" published in the