Centrifugal blower system and fuel cell incorporating same

1. A centrifugal blower system comprising:

a) a series of blower units, each blower unit in the series of blower units comprising a casing having an axial inlet and a radial outlet, a substantially tangential wall of the casing extending to the outlet, an impeller disposed within the casing for drawing a gaseous medium at a first pressure into the axial inlet and expelling gaseous medium at a second higher pressure through the radial outlet along a trajectory inclined to the substantially tangential wall, and a motor for driving the impeller;

b) a duct directly connecting the radial outlet of at least one upstream blower unit in the series of blower units with the axial inlet of at least one successive downstream blower unit in the series of blower units; and

c) a microprocessor in communication with the blower units of the series of blower units and configured to control independently the operation of the blower units in the series of blower units.

2. The centrifugal blower system of claim 1 in which the orientation of the radial outlet of one blower unit in the series of blower units to the axial inlet of a successive blower unit in the series of blower units is approximately 0°, 90°, 180° or 270°.

3. The centrifugal blower system of claim 1 in which the angle of pitch of the radial outlet of one blower unit in the series of blower units to the axial inlet of a successive blower in the series of blower units is approximately 0°, 30°, 60° or 90°.

4. The centrifugal blower system of claim 2 in which the angle of pitch of the radial outlet of one blower unit in the series of blower units to the axial inlet of a successive blower in the series of blower units is approximately 0°, 30°, 60° or 90°.

5. The centrifugal blower system of claim 1 wherein at least one blower unit in the series of blower units has greater gas pressure and gas flow capability than another blower unit in the series of blower units in the centrifugal blower system.

6. The centrifugal blower system of claim 1 wherein at least one blower unit in the series of blower units is separated from the corresponding successive blower unit in the series of blower units in the centrifugal blower system.

7. The centrifugal blower system of claim 1 wherein the radial outlet of a successive blower unit in the series of blower units is connected to a gas stream housing and the interior walls of a duct connecting the radial outlet of a prior blower unit in the series of blower units to the axial inlet of the successive blower unit in the series of blower units and interior walls of the gas stream housing are at an angle αof from 12° to 20° relative to the radial outlets of the prior and successive blower units in the series of blower units.

8. The centrifugal blower system of claim 1 wherein interior walls of a duct connected at one end thereof to the radial outlet of a prior blower unit in the series of blower units are configured to be substantially parallel to the trajectory of gaseous medium expelled from such radial outlet, the angle of pitch of the radial outlet of the prior blower unit in the series of blower units to the axial inlet of the successive blower unit in the series of blower units is approximately 0°, the radial outlet of the successive blower unit in the series of blower units is connected to a gas stream housing and the interior walls of the duct connecting the radial outlet of the prior blower unit in the series of blower units to the axial inlet of the successive blower unit in the series of blower units and the interior walls of the gas stream housing are at an angle αof from 12° to 20° relative to the radial outlets of the prior and successive blower units in the series of blower units.

9. The centrifugal blower system of claim 1 wherein the microprocessor is configured to independently control the operation of blower units in the series of blower units such that operation of at least one blower unit in the series of blower units provides from 50% to 90% of a target gaseous flow of the centrifugal blower system and the operation of at least one other blower unit in the series of blower units provides the balance of the target gaseous flow of the centrifugal blower system.

10. The centrifugal blower system of claim 9 wherein the radial outlet of a successive blower unit in the series of blower units is connected to a gas stream housing and interior walls of a duct connecting the radial outlet of a prior blower unit in the series of blower units to the axial inlet of the successive blower unit in the series of blower units and the interior walls of the gas stream housing are at an angle a of from 12° to 20° relative to the radial outlets of the prior and successive blower units in the series of blower units.

11. The centrifugal blower system of claim 9 wherein interior walls of a duct are configured to be substantially parallel to the trajectory of gaseous medium expelled from such radial outlet, the angle of pitch of the radial outlet of the prior blower units in the series of blower units to the axial inlet of the successive blower unit in the series of blower units is approximately 0°, the radial outlet of the successive blower unit in the series of blower units is connected to a gas stream housing, and the interior walls of the duct connecting the radial outlet of the prior blower unit in the series of blower units to the axial inlet of the successive blower unit in the series of blower units and the interior walls of the gas stream housing are at an angle α of from 12° to 20° relative to the radial outlets of the prior and successive blower unit in the series of blower units.

12. A method of controlling the operation of the centrifugal blower system of claim 1 which comprises:

a) operating at least one blower unit in the series of blower units to provide from 50% to 90% of a target gaseous flow of the centrifugal blower system; and,

b) operating at least one other blower unit in the series of blower units to provide the balance of the target gaseous flow of the centrifugal blower system.