period three

The Compressor in a System

notes

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Figure 42

Period Two presented several methods used to control the capacity of a compressor. This next section considers the entire system in order to determine how the capacity of the compressor is controlled to maintain desired space conditions.

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Figure 43

System-Level Control

The method of controlling compressor capacity to maintain desired space conditions depends on 1) whether the system is a chilled-water or a direct- expansion system, and 2) how the airside system responds to changes in space loads.

Generally, in air-conditioning applications, compressors will be applied in either

achilled-water or a direct-expansion (DX) system. A chilled-water system uses water as the cooling media. The refrigerant inside the evaporator absorbs heat from the water, and this water is pumped to coils in order to absorb heat

30

TRG-TRC004-EN

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Trane TRG-TRC004-EN manual Compressor in a System, Vwhp/Hyho&Rqwuro, System-Level Control