OVERVIEW

Ventilation of an enclosed space is usually for the purposes of controlling the air temperature, humidity, and/or chemical composition. When humans occupy the space (room), the ventilation is necessary to provide adequate breathing oxygen and to transport the waste heat and moisture produced by the occupants. Normally, the waste heat and moisture far exceed the breathing oxygen ventilation requirement.

The heat and moisture release rates by the occupants are functions of their activity level, age, size, and sex. The fraction of energy associated with heat transferred to the air by convection and surrounding surfaces by radiation is called sensible heat while that associated with moisture evaporation is called latent heat. These fractions vary, depending on activity level and environmental state. In addition to the occupant heat and moisture load there may be an equipment and lighting load ventilation requirement.

It is normally assumed that the room air is homogeneous and is the same as the room air exhaust state.

Basic Refrigeration Cycles:

Reference - ASHRAE Handbook of Fundamentals.

Gas Compression-Expansion Refrigeration Cycle:

Human Factors and Constants: