Product manual

In ZX MT units, suction line injection is applied to the compressor suction. Suction line injection allows a reliable and efficient MT
envelope of up to -15 deg C (R22) and -20 deg C (R404A) evaporating temperature. In suction line injection, a part of liquid refrigerant is
added into the compressor suction gas. Suction injection de-superheats the suction gas and controls the compressor discharge
temperature. This is implemented through electronic control by the E2 controller and an electronic expansion valve (EXV). The E2
monitors the compressor discharge temperature and optimizes the opening of the EXV for optimal discharge gas control.
In ZX LT units, vapor Injection is applied to the compressor. Vapor injection enhances the compressor efficiency by applying 2-stage
compression with an economizer refrigeration cycle. Vapor injection eliminates the need for liquid injection, which would otherwise have
been required to operate a reliable LT envelope down to -40 deg C evaporating temperature. In vapor injection, a part of liquid refrigerant
is expanded and passed through a heat exchanger. In the heat exchanger, this expanded refrigerant absorbs heat from the main liquid line
and sub-cool the main liquid. The expanded refrigerant vaporizes while passing through the heat exchanger and is supplied back into the
scroll intermediate pockets through the vapor-injection tube. The sub-cooling of the main liquid increases the compressor capacity by as
much as 30%. The figure 06 below identifies the key components of the vapor injection assembly.
5
Emerson ZX Platform Condensing Unit
PRODUCT MANUAL
ZXI Vapor Injected
Scroll Compressor
Vapor Injection control EXV
Vapor Injection Tube
To Compressor
Vapor/ Liquid Sub Cooling PHE
Figure 06