Optional Energy Recovery Wheel
www.DaikinApplied.com
81
IM 1125-13 • REBEL ROOFTOPS
Optional Energy Recovery Wheel
System Description
When a unit is equipped with an optional enthalpy wheel, energy
recovery is provided by drawing outside air across half of the
enthalpy wheel and drawing exhaust air across the other half.
Latent heat and sensible heat are transferred from the hotter
and moist exhaust air to the colder and dry outside air during
winter conditions. Latent heat and sensible heat are transferred
from the hotter and moist outside air to the cooler and dry
exhaust air during summer conditions. Energy recovery control
consists of starting and stopping an exhaust fan, modulating
the speed of the exhaust fan, starting and stopping an enthalpy
wheel, optionally controlling the speed of the enthalpy wheel
and opening and closing a set of bypass dampers. The outdoor
dampers are controlled in the normal manner.
Definitions
The following are descriptions of various components related
to the enthalpy wheel construction (
Bearing, external
- The wheel and bearing rotate on the shaft,
no field lubrication is required.
Brush seal
- The seal used for both the circumferential seal
and the inner seal in the cassettes. They are constructed of
nylon brush and configured to seal against the enthalpy wheel
band in the case of the circumferential seal, and against the
wheel face in the case of the inner seal. These seals are full
contact seals, have an integral clip, and they are clipped to the
cassette face panel cutout (circumferential) or to the (inner)
post .
Cassette
- The steel structure that houses the rotor. Cassettes
are of punched sheet metal panel construction.
Enthalpy wheel
- A generic name for an energy conservation
wheel. The term “enthalpy” refers to an air stream’s total
energy (temperature and humidity level).
Exhaust air
- The air stream that is exhausted to the outside.
Exhaust air is building return air that has been run through the
enthalpy wheel.
Heat wheel
- Synonymous with an enthalpy wheel, energy
conservation wheel, or total energy recovery wheel. Some heat
wheels are sensible only wheels and should not be confused
with Daikin total energy recovery wheels.
Hub
- The center support of an enthalpy wheel.
Latent energy
- Latent energy, in the context of enthalpy wheel
discussions, is the work done by the wheel to transfer moisture
from one air stream to another. Latent work is accompanied by
humidity changes in the air streams.
Media
- The chemical composite part of the enthalpy wheel
which actually performs the latent and sensible exchange.
Outdoor air
- The air stream that is brought in from the outside.
Outdoor air becomes supply air after going through the enthalpy
wheel.
Purge
- A small segment of supply air defined by the gap
between the inner seal on the outdoor air edge of the center
post and the supply air edge of the center post. The purge angle
is adjustable. The purge captures the small amount of supply air
captive in the enthalpy wheel when the wheel moves from return
to supply and routes it to return to minimize cross contamination.
Return air
- The air stream that is returned from the building.
Return air becomes exhaust air after going through the enthalpy
wheel.
Rotor
- The part of an enthalpy wheel that performs the energy
exchange and consists of the wheel media, hub, spokes and
band .
Sensible heat
- Sensible energy, in the context of enthalpy
wheel discussion, is the work done by the enthalpy wheel to
transfer heat from one air stream to another. Sensible work is
accompanied by temperature changes in the air stream.
Supply air
- The air stream that is supplied to the building
space. Supply air is outdoor air that has been run through the
enthalpy wheel.
Arrangements
Two arrangements are offered for the enthalpy wheel:
1 .
Single enthalpy wheel with economizer and bypass
(
). This arrangement is available for all units.
2 .
Single enthalpy wheel without economizer (100%
outdoor air unit).
Wheel Construction
Your Daikin enthalpy wheel is delivered completely assembled
and ready to run. The wheel is built to provide many years of
trouble free service following proper installation and performance
of the minimal maintenance requirements.
