Air-Cooled Models; How It Works; Air Flow; Refrigeration System - Ingersoll-Rand DXR Series Operator's Instruction Manual

tions in water temperature, water pressure and dryer air
load.
Operating the dryer with inadequate condenser cooling
water (temperatures above or pressures below those in
Table 1) will cause a rise in dew point unless the dryer
inlet airflow is reduced. The refrigerant discharge pres-
sure control will shut down the refrigerant compressor if
cooling water is inadequate.
If the cooling water is dirty, install a strainer ahead of
the condenser inlet. Install shutoff valves so that the
strainer can be drained and cleaned at regular intervals.
COOLING WATER REQUIREMENTS
WATER
DRYER
CONN.
MODEL
(in NPT)
DXR425-W
3
8
DXR600-W
3
8
DXR800-W
1
2
DXR1000-W
1
2
a
Minimum water pressure is 25 psig for city water and 35 psig for
tower water. Maximum water pressure is 150 psig.

Air-Cooled Models

Cooling air must be drawn from a clear, well-ventilated
area to reduce dust and dirt accumulation on the con-
denser coils. Air temperature should not exceed 100°F.
Required air flow rates are shown in Table 2.
COOLING AIR REQUIREMENTS
MODEL
DXR425
DXR600
DXR800
DXR1000

HOW IT WORKS

Air Flow

DXR Series dryers use refrigeration cooling to condense
entrained moisture out of the airstream (see Figure 2).
Warm saturated air enters the air- to-air heat exchanger
where it is cooled by outgoing cold air. The inlet air is
further cooled in the refrigeration chiller. Cooling con-
denses entrained moisture. The condensate is removed
by a centrifugal separator and an automatic drain valve.
DXR Series Dryers (Bulletin 553)
Table 1
COOLING WATER
a
REQUIRED
60°F 70°F 80°F 85°F
GPM GPM GPM GPM
0.6 1.0 2.1 2.7
1.6 2.0 2.8 3.8
1.5 2.0 3.7 5.4
2.5 3.0 4.5 5.7
Table 2
COOLING AIR
(cfm)
3000
2700
5200
4800
The cold, dry air is reheated by incoming warm air as it
passes back through the air-to-air heat exchanger. Using
the outgoing air to pre-cool the inlet air condenses up to
65 percent of the moisture out of the inlet air before it
reaches the chiller. Pre-cooling the inlet air reduces the
heat load on the refrigerant compressor, permitting the
use of a smaller refrigerant compressor.

Refrigeration System

The refrigeration system is designed and fabricated in
accordance with recognized commercial/industrial prac-
tices. It consists of a compressor and the controls, safety
interlocks and associated equipment necessary for safe
performance.
A thermostatic expansion valve (TEV) and a hot gas by-
pass valve (HGBV) are used to modulate the refrigerant
flow. The TEV adjusts the flow of liquid refrigerant to
90°F
the chiller. A temperature sensor downstream of the
chiller opens and closes the TEV in response to the tem-
GPM
perature of the refrigerant leaving the chiller to maintain
4.2
the proper cooling rate under all load conditions. The
5.5
HGBV delivers hot refrigerant gas to the chiller in re-
sponse to changes in refrigerant pressure. This prevents
10.0
icing in the chiller and short cycling in the refrigerant
9.0
compressor during extended periods of system opera-
tion at low load.
All refrigerant valves are adjusted at the factory; opera-
tion is fully automatic.
Air and refrigerant flow schematic.
Figure 2.
1-3