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7.0 PRINCIPLES OF OPERATION
7.1 INTRODUCTION
Ingersoll Rand
Nirvana™ Cycling dryers remove moisture
from compressed air by cooling the air temperature to
between 36° and 40°F (2 and 4°C). This causes vapors to
condense into liquid droplets which can then be easily
removed from the air. The major systems of the dryer which
contribute to its operation are the Air System, the Moisture
Removal System, the Refrigeration System, the Thermal
Mass Circulating System and the Controls. The following
paragraphs describe each of the systems in greater detail.
7.2 AIR SYSTEM
The air system consists of the dryer components which are
in contact with the compressed air. Referring to Figure 1
and following the bold “AIR FLOW,” hot saturated air from
the compressor enters the precooler/reheater where the air
temperature is reduced prior to entering the chiller by the
cool air exiting the air/moisture separator. This precooling
allows for the use of a smaller refrigeration system. The air
then goes into the chiller section where it is further cooled
to the desired dew point by a thermal mass fluid. The
temperature of the thermal mass fluid is maintained by the
refrigeration circuit and controls. The air continues to the
separator where moisture is removed, thereby, allowing the
cool, dry air to return back to the precooler/reheater to be
heated by the incoming moist hot air. The air exiting the
“reheater” portion of the dryer should be approximately 15°-
20°F lower than the inlet air temperature based on standard
conditions at full rated flow.
7.3 MOISTURE REMOVAL SYSTEM
Ingersoll Rand
condensate drains discharge condensed
moisture and lubricants (condensate) from compressed air
equipment. Consistent discharging of condensate from
compressed air equipment is essential for proper equipment
operation and performance. The drain valve is designed for
trouble-free and maintenance free draining of unwanted
accumulations of condensation and other foreign matter
from any collection point in a compressed air system without
the need for electricity.
The high pressure condensate drain installed on the dryer
requires the user to supply clean dry air (80 - 120 psig)
for proper operation. Refer to the instruction label on the
condensate drain for details. A small volume of air must be
displaced (vented to atmosphere) to allow for the collection
of condensate. Make certain the vent valve on the drain is
open to assure proper drain operation.
7.4 REFRIgERATION SYSTEM
The Refrigeration System consists of all the components
which handle. This is a hermetically sealed closed-loop
system. Referring to Figure 1 and following the phantom
“REFRIG FLOW,” refrigerant is shown leaving the evaporator
section where, in the process of removing heat, it is changed
from a low pressure liquid into a low pressure gas. This
gas enters the suction side of the compressor where it is
compressed into a high pressure gas. The high pressure
gas is cooled in the air cooled or water cooled condenser
section until it becomes a high pressure liquid. It then
goes through a permanent filter dryer that ensures the
refrigeration system is free of contaminants. A thermostatic
expansion valve meters the refrigerant for introduction into
the evaporator. The refrigerant pressure is reduced upon
entering the evaporator where as it evaporates, heat is
removed from the thermal mass fluid.
7.5 THERMAL MASS CIRCULATINg SYSTEM
The thermal mass fluid in a
Ingersoll Rand
Nirvana™
Cycling dryer is continuously circulated in a closed pump
loop system. Referring to Figure 1 and following the dashed
“THERMAL MASS FLUID” line, the heat is removed from
the fluid in the evaporator by the refrigeration system. The
thermal mass reservoir is sized to minimize refrigeration
cycles during reduced air load periods. The thermal mass
fluid is pulled from the bottom of the reservoir and pumped
through the chiller, removing heat from the air and returned
to the evaporator. The pump utilized on
Ingersoll Rand
Nirvana™ Cycling dryer is a maintenance-free, quiet cartridge
circulator pump similar to those used in residential water
systems. While the refrigeration system cycles on and off
based on loading conditions, the circulating pump runs
continuously to maintain flow through the chiller at all times.
120.26A D4290NCHPW400F Installation Operation and Maintenance Manual
