Mechanical cleaning, Service – AAON LL-540 User Manual
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rejected), if the bleed setting is manual
based on design heat load, too much water
will be removed when the heat load is less
that design.
The AAON evaporative-cooled condenser is
equipped with a de-superheater. The de-
superheater coil is located above the mist
eliminators. Approximately 22% of the total
heat of rejection is accomplished with the
de-superheater. Water usage of the AAON
evaporative-cooled
condenser
is
approximately 22% less than evaporative-
cooled condensers not equipped with a de-
superheater.
One method of calculating evaporation and
bleed in gallons per minute (gpm) is shown
as follows:
Evaporation Rate
=
⁄
⁄
⁄
=
⁄
⁄
Bleed Rate
=
Example:
A unit has 100 ton cooling capacity with a
compressor EER = 15
Total Heat of Rejection
= Unit Capacity in Tons Ч 12000 Ч
(
)
= 100 Ч 12000 Ч
(
)
= 1,473,040 Btu/hr
Total Full Load Heat of Rejection via
Evaporation
= Total Heat of Rejection ×
(1 – fraction of heat rejected by de-
superheater)
= 1,473,040 Btu/hr × (1 – 0.22)
= 1,148,971 Btu/hr
Note that approximately 22% of the total
heat of rejection is accomplished with the
de-superheater at full load. So, the fraction
of heat rejected by the de-superheater (in the
equation above) is approximately 0.22 at full
load and increases as the ambient dry bulb
decreases.
Evaporation Rate
=
⁄
⁄
⁄
= 2.19 gpm
Assuming 4 cycles of concentration:
Bleed Rate
=
= 0.73 gpm
Mechanical Cleaning
Do not attempt to mechanically clean the
copper tubing in the evaporative-cooled
condenser. Do not use wire brushes or any
other mechanical device on the copper
tubing. Severe damage may result. Contact
your
water
treatment
expert
for
recommendations on chemical cleaning
procedures.
Service
If the unit will not operate correctly and a
service company is required, only a
company with service technicians qualified
and experienced in both refrigerant chillers
and air conditioning are permitted to service
the systems to keep warranties in effect. If
assistance is required, the service technician
must contact AAON.