Filter
Top Products
TRG-TRC004-EN 31
period three
The Compressor in a System
notes
from the air used for space conditioning. In contrast, the refrigerant inside the
evaporator of a direct-expansion (DX) system absorbs heat directly from the
air used for space conditioning.
The airside system responds to changing space loads by varying either the
temperature or the quantity of air delivered to the conditioned space. A
constant-volume system provides a constant quantity of variable-
temperature air to maintain the desired conditions in a space. A variable-air-
volume (VAV) system, however, maintains the desired space conditions by
varying the quantity of constant-temperature air.
Again, a constant-volume system supplies the same quantity of air to the space
and varies the temperature of this air to respond to changing loads.
In this example single-zone, constant-volume DX system, in order to respond to
changing space loads, the capacity of the compressor is controlled by directly
sensing space temperature. The compressor is loaded or unloaded based on
how close the actual space temperature is to the set point temperature.
Loading and unloading the compressor results in a temperature change of the
air leaving the evaporator coil.
&RQVWDQW9ROXPH';6\VWHP
';FRROLQJ
';FRROLQJ
FRLO
FRLO
WKHUPRVWDW
WKHUPRVWDW
VXSSO\
VXSSO\
IDQ
IDQ
FRPSUHVVRU
FRPSUHVVRU
FDSDFLW\
FDSDFLW\
FRQWUROOHU
FRQWUROOHU
Figure 44