Air handling system

Air handling system including a heat recovery means including blowers and dampers for controlling air flow and a desiccant wheel movable into and out of the air stream to selectively recover heat from exhaust air and transfer it to outside air. The air handlling system may also include an air conditioning system and an economizer inclulding dampers to control recirculated air and inlet and exhaust air.

This invention relates to air handling systems and more particularly to 
systems including an economizer system and a heat recovery system in which 
the heat recovery system is selectively employed when heat transfer to or 
from exhaust air and/or inlet air is desired and is inoperative and does 
not interfere with air flow when heat recovery is not desired. The term 
"heat recovery" is used herein in its broadest sense to mean transfer of 
heat between outside and exhaust air. 
Both economizers and heat recovery systems such as desiccant wheels are old 
and well known as separate systems. They have never been utilized 
together. A system design has incorporated either an economizer or a heat 
recovery unit, but not both because the economizer must be able to deliver 
100% outside air to the system, and the recovery units designed to do the 
same would be prohibitively large and far too expensive. 
New ASHRAE standards are requiring buildings to bring in more and more 
outside air. In some applications the standards may require as much as 40% 
to 50% outside air. 
This invention permits combining an economizer and heat recovery system for 
the first time in an economical design. 
An object of this invention is to permit the combination of an economizer 
and heat recovery system in an economical design. 
Another object is to provide a combination economizer and heat recovery 
system in which the heat recovery means is selectively positioned in and 
removed from the flow stream of the inlet and exhaust air. 
Another object is to provide a heat recovery system employing a desiccant 
wheel in which the wheel is selectively moved into and out of the inlet 
and exhaust air flow so that the economizer may function in the 
conventional manner when the wheel is moved to an out-of-the-way position. 
Other objects, features and advantages of this invention will be apparent 
from the drawings, specification and claims.

FIG. 1 illustrates the system operating with partial return air and partial 
fresh outside air. The system includes the conventional air conditioning 
components such as the compressor 10, the condenser 11, condenser blower 
12, evaporator 13, blower 14 for circulating air through the building and 
across the evaporator or cooling coil. These elements are set up and 
connected in the conventional manner (not shown) to cool and circulate 
air. This system may also be operated in a reversing mode commonly 
referred to as a heat pump. 
The system includes a conventional economizer indicated generally at the 
area designated as 15 which includes dampers 16 and 17 which may be 
partially or fully opened or closed to control air flow. Inlet air is 
admitted through damper 16 and recirculated air through damper 17. Outlet 
18 provides for exhaust air from the economizer. 
A heat recovery unit is shown generally at 19. The unit includes inlet 
blower 21 with dampers 22 positioned horizontally to either side of the 
blower 21. The blower 21 and dampers 22 communicate with the inlet dampers 
16 of the economizer 15 and inlet air from the blower 21 pass through 
dampers 16 and feed into the inlet air chamber. Inlet air is drawn into 
the flowway 23 of the heat recovery unit through inlet 24. Outlet air from 
the conditioned space passes through economizer outlet 18 into flowway 25 
of the heat recovery unit. Outlet air is drawn from flowway 25 and 
exhausted to the exterior by outlet blower 26. 
In accordance with this invention the heat recovery means is selectively 
positioned in and removed from the flow of exhaust air and outside air. 
Preferably the heat recovery means is a desiccant wheel 27 which in its 
FIG. 1 position rotates about its central axis in the path of exhaust air 
and inlet air. In the conventional manner heat is transferred between 
these two air streams. To provide for selectively transferring heat the 
wheel 27 is mounted for movement into and out of the path of these two air 
streams. Preferably the wheel is mounted for rotation about a diameter 
line passing through the wheel. This rotation is provided by journal on 
opposite sides of the wheel which support the wheel in the heat recovery 
unit. One of these journals is shown at 28 in FIGS. 1 & 2. An identical 
journal is provided on the other side of the wheel to provide for rotation 
between the FIGS. 1 and 2 positions. 
FIG. 2 shows the system operating with the wheel 27 in the out-of-the-way 
position. Thus the economizer is operable and the heat recovery system is 
not operable. For instance with damper 17 closed and dampers 16 and 22 
open the blower 14 may move 10000 C.F.M of air through the system. Both 
blowers 21 and 26 may be bypassed if desired, or blower 26 may be used as 
a means of power exhaust from the space. 
FIG. 1. shows the economizer and heat recovery system in operation. Again 
the blower 14 may be moving 10000 C.F.M of air through the system. The 
wheel is in operative position to reclaim heat. The inlet air blower 21 
may be set to introduce various quantities of air, say 2000 C.F.M. into 
the system with the dampers 22 closed. The outlet blower may be set to 
exhaust the same quantity, in this case 2000 C.F.M. of air from the 
system. With this arrangement 8000 C.F.M. of air will pass through 
economizer damper 17. 
If desired the economizer inlet damper 16 and heat recovery inlet damper 22 
may be combined in a single damper. 
The foregoing disclosure and description of the invention are illustrative 
and explanatory thereof and various changes in the method and apparatus 
and system and in the size, shape and materials, as well as in the details 
of the illustrated construction, may be made within the scope of the 
claims without departing from the spirit of the invention.