Optional Energy Recovery Wheel; Energy Recovery Wheel Design - Daikin MPS015 F Installation And Maintenance Manual

Energy Recovery Wheel Design

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 .
Arrangements
Three arrangements are offered for the enthalpy wheel:
1 . Single enthalpy wheel with economizer and bypass (see
Figure 41). This arrangement is available for all units.
2 . Single enthalpy wheel without economizer (100%
outdoor air unit) for airflow up to about 7000 CFM. This
arrangement is available on sizes 015 - 040C and 800 -
802C only.
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.
Definitions
The following are descriptions of various components related
to the enthalpy wheel construction (see
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 (concumferential) or to the (inner) post.
Cassette – The steel structure that houses the rotor. Cassettes
are of punched sheet metal panelized 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).
www.DaikinApplied.com
Figure 41):
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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.
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