2.6.3
Fans (Solid Desiccant System) For Supply and Regeneration
The unit shall be equipped with two belt driven backward inclined blowers.
A drive belt rated for minimum 150% of motor horsepower shall be used on
each motor. The supply fan motor shall have sheaves for air balancing.
The motors shall be nominal 3500 RPM, NEMA B with open dripproof housings
and a minimum service factor of 1.15.
2.6.4
Heating System (Solid Desiccant System)
Regeneration and process heating coils shall be of the finned tube type,
and shall be constructed of 13 mm 1/2 inch OD seamless copper tube
mechanically bonded to aluminum fins. The coils shall include a flanged,
heavy-gauge, galvanized steel housing for mounting to the unit. The coils
shall be rated for 1135 kPa 150 psig.
2.6.5
Filters (Solid Desiccant System)
Outside air inlets and return air plenums shall be equipped with 50 mm 2
inch, 30% minimum efficiency filters. Filters shall be pleated and
disposable.
2.6.6
Indirect Evaporative Cooling System (Solid Desiccant System)
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NOTE: Where water is of high hardness (alkalinity),
provisions shall be made to facilitate automatic or
manual blowdown to reduce solids build-up.
Alternatively, water should be softened prior to use
as make-up for the evaporative cooling system.
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Evaporative cooling shall be used to indirectly cool the supply air. The
system shall include: An evaporative cooling media of cellulose paper
impregnated to resist degradation and PVC piping.
2.6.7
Gas Fired Boiler (Solid Desiccant System)
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NOTE: Boiler regeneration capacity, as determined
by the manufacturer, may be based on the
regeneration capacity required under "design day"
conditions, or 1% or 2.5% summer outdoor design
conditions. The supporting rationale behind such
sizing is that the specific humidity of the air
leaving the desiccant will be fairly constant over
variable outdoor conditions. The boiler will
substantially regenerate the desiccant at relatively
high outdoor dry-bulb temperatures and specific
humidity ratios, while full-capacity regeneration at
lower outdoor dry-bulb temperatures and specific
humidity ratios will still produce a process air
stream with a specific humidity ratio comparable to
that achieved at outdoor conditions of higher
dry-bulb temperature and specific humidity ratio.
This approach minimizes the expense of a higher
capacity boiler, boiler short-cycling at light
dehumidification loads and the unnecessary expense
of excessive dehumidification. If a higher capacity
SECTION 15500A
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