Handbook of air conditioning and refrigeration / Shan K

26.2 CHAPTER TWENTY-SIX
The purpose of classifying air conditioning systems is to distinguish one type from another and to
provide a background for the selection of an optimum air conditioning system based on requirements.
As each air condition system consists of air, water, heating, and refrigeration systems, the classification
of air conditioning systems and is often mixed with the classification of air systems and water and
refrigeration systems. If a designer cannot properly classify an air conditioning system and distinguish
it from others, it will be difficult for him or her to select an appropriate system for the client.
During the classification of air conditioning systems, the following points should be considered:
● The classification of air conditioning systems, or HVAC&R systems, should include the primary
aspects of air systems as well as heating and cooling systems if possible, as the air system directly
affects the control of the indoor thermal environment and indoor air quality.
● The system and the primary equipment used should be compatible with each other. For example,
the primary equipment in a unitary packaged system is the packaged unit.
● System classification should mainly be based on practical applications. For example, as the indoor
air quality becomes one of the primary criteria used to select an air conditioning system,
it must be considered whether an “all-water system” without outdoor ventilation air supply can
exist.
● System classification should be simple, and each of the air conditioning systems should be clearly
different from the others.
Air Conditioning Systems Classification
As discused in Chap. 1, air conditioning systems can be classified currently into eight categories according
to their configurations and operating characteristics:
● Individual room air conditioning systems or simply individual systems
● Evaporative cooling air conditioning systems
● Desiccant-based air conditioning systems or simply desiccant systems
● Thermal storage air conditioning systems or simply thermal storage systems
● Clean room air conditioning systems or simply clean room systems
● Space conditioning air conditioning systems or simply space systems
● Unitary packaged air conditioning systems or simply packaged systems
● Central hydronic air conditioning systems or simply central systems
First, as discussed in Sec. 1.5, the individual, space, packaged, and central systems together had
more than 98 percent of floor area both in commercial buildings in 1992 and in air conditioned
homes in 1991 in the United States. Clean room and desiccant-based air conditioning systems are
often processed air conditioned systems. Except where deep-well water or an air economizer is
available, evaporative cooling systems are the cheapest cooling systems and are widely used in arid
southwestern areas of the United States. Thermal storage systems have a quite different water system
and operating characteristics from a central system. Second, there are many specific air conditioning
systems used in many industrial applications such as air conditioning used for textile mills
with air washers, and also new air conditioning technology will be invented and developed. As soon
as their importance and their distinct system characteristics are recognized by the HVAC&R industry,
a new category of air conditioning system should be added.
Air, Heating, and Cooling Systems Designation
The title of air conditioning systems listed in later sections of this chapter and succeeding chapters,
such as VAV reheat rooftop packaged systems, also designates the air, heating, and cooling systems: