INGENIEUR
Option III: Schedule of DOAS System with Enthalpy Wheel, Cooling Coil and Sensible Wheel
OPTION III: Rotary Passive Desiccant Heat
Exchanger With Coil And Rotary Sensible Heat
Exchanger. (EW+CC+SW) higher CHW, lower ADPs resulting in
reduced pressure drops and better IKW/TR
for chiller.
This option is designed with the following
objectives: Always provide conditioned air that
is drier than the air in the space. Deliver cold
conditioned air whenever possible, and use
recovered energy to reheat during mild weather.
Select equipment to limit indoor relative
humidity to 55% in all seasons
This option has all the features of OPTION
II and in addition supplies air at almost room
temperature. The advantage here lies in the fact
that during moderate weather, i.e. when outside
ambient temperature is low but latent loads are
high (typically monsoons), the OPTION II too can
have difficulty in handling the RH.
This option supplies air at almost room
temperature with lower dew point than space,
hence it can continue to control the moisture
without the risk of lowering the temperature.
The benefits of this option are
i) Possibility of obtaining substantial LEED
points,
ii) Good RH control in all the seasons,
iii) Reduced installed tonnage and lower power
consumption of HVAC system, and
iv) Internal sensible cooling devices have OPTION IV: Active Desiccant Dehumidification
Wheel (With Condenser Heat Reactivation)
Coupled With DX Cooling Coil. (CC+ADESW)
6
36
VOL
2019
VOL 77
55 JANUARY–MARCH
JUNE 2013
This option combines the benefits of desiccant
dehumidification with cooling of the DX air
conditioners. Contrary to the first two options,
this approach uses desiccant wheel to remove
moisture and lower the dew point of the supply air
instead of using a cooling coil.
The reactivation of the desiccant wheel
is undertaken by recycled heat from the DX
condenser air.
The benefits of this option are:
i) M e e t s A S H R A E s t a n d a r d 9 0 .1
requirements,
ii) The co-efficient of performance (COP) is
65% more than a conventional DX system
with reheat,
iii) Uses recycled heat from DX system for
reactivation,
iv) No active reheat required, and
v) Maintains RH control in all the seasons
(including for areas having high internal
latent loads).