Retrotec USACE - Manual (Page 202)

D72 ENERGY & PROCESS ASSESSMENT PROTOCOL
Air supply systems that must provide both cooling and dehumidifi cation
are typically designed in a manner that wastes chiller and boiler plant energy.
Using “standard” AHU design strategies that dehumidify the air and then
reheat it to reduce RH can waste 50% or more of the chiller plant and boiler
plant energy when compared to using AHU designs based on high-effi ciency
dehumidifi cation system (HEDS) design strategies for dedicated outside air
systems (DOAS) or variable air volume (VAV) systems combined with a sepa-
rate heating and cooling system.
D.4.2.15 No Chiller Waste Heat Reclaim (Waste)
A water sourced heat pump can provide some of the cooling to the facility, and
the rejected heat from the cooling process can be used to heat the domestic
water loads. The water source heat pumps (WSHPs) must have a cooling load
to dump the cooling into, and in the case of several facilities connected to a
chiller, domestic water loads can provide a great heat sink to dump the heat
into.
D.4.2.16 Insuffi cient Cooling Load Provided by Existing Chiller
System (Ineffi ciency)
Install WSHPs to augment the capacity of the hot water boiler and to reduce
the cooling load on the existing chiller systems when heat is required. A 20-ton
WSHP can deliver approximately 320,000 BTUH of heat when it is loaded up.
D.4.2.17 Cooling Tower Dirty Distribution Nozzles (Waste)
A cooling tower is a heat exchange device where water is cooled by passing
air through it, providing for evaporation. The evaporation of some of the
water removes heat and cools the rest of the water. In a cooling tower, water
is pumped to the top of the tower, where it enters a piping header system.
There are openings in these headers where nozzles are placed to provide a
spray pattern to the downward-fl owing water. This distributes small drop-
lets of water properly across the fi ll section of the tower. Here a number of
closely spaced vertical panels are placed so the water can fl ow over them as
it drops downward. The fi ll section slows the progress of the fl owing water
and provides time for water evaporation. There may be several fi ll sections
needed to obtain the desired cooling of the water. The cooling of the water
can be increased by moving more air through the cooling tower, and there
are fans placed in the tower for this reason. Normally the fans are variable
fl ow or have variable pitched blades to obtain the correct air fl ow from the
desired water cooling.