Indirect air-side economizer for removing heat from enclosed spaces with high internal heat generation
An Indirect Air-Side Economizer based around an air-to-air heat exchanger is provided that is advantageously operated in conjunction with other components in an integrated system to facilitate necessary rejection of heat and certain removal of particulate from the air within a data center. The disclosed device may include separate cooling methodologies that can be operated independently to cool return air from that data center.
1 . An air cooling device, herein named an Indirect Airside Economizer (IASE) comprising:
at least one air-to-air heat exchanger for exchanging heat between a primary recirculation air flow path and a secondary outdoor air flow path;
an outside air pre-cool section, located in the secondary outdoor air flow path, including at least one pre-cooler;
a refrigeration condenser/heat rejection coil positioned on a downstream side of the outside air pre-cool section;
at least one condenser fan that pulls pre-cooled outdoor air through the refrigeration condenser/heat rejection coil;
at least one scavenger air fan that pulls pre-cooled outdoor air through the at least one air-to-air heat exchanger via the secondary outdoor air flow path; and
at least one recirculation air fan that recirculates primary air from an enclosed space for the purpose of rejecting heat, the secondary outdoor air flow path including an outside air inlet through which outside air is drawn into the outside air pre-cool section including the at least pre-cooler, the secondary outside air taking on two flow paths, a first flow path passing through the refrigeration condenser/heat rejection coil with a condenser outlet opening on an exhaust side of the refrigeration condenser/heat rejection coil that includes the at least one condenser fan for exhausting heated air from the refrigeration condenser/heat rejection coil, and the second air flow path passing through one side of the at least one air-to-air heat exchanger via the secondary outside air flow path into an exhaust outlet by which the outside air, having extracted heat from the recirculating air from the enclosed space, the recirculating air flowing through another side of the at least one air-to-air heat exchanger via the primary recirculation air flow path, is exhausted by the at least one scavenger air fan positioned on an outlet side of the air-to-air heat exchanger in the secondary outdoor air flow path, and
the primary recirculation air flow path including a return air inlet through which warm return air from the enclosed space with high internal heat generation is drawn, by means of the at least one recirculation air fan, through the at least one air-to-air heat exchanger, followed by the refrigeration evaporator/cooling coil and a supply outlet via which the cooled recirculation air is supplied back to the enclosed space as supply air at a temperature as appropriate for equipment located within the enclosed space.
2 . The air cooling device according to claim 1 , wherein the enclosed space is a computer data center including multiple computer data servers and ancillary support devices, and the supply air is circulated through the multiple computer data servers to extract the heat generated by the servers.
3 . The air cooling device according to claim 1 , wherein the warm return air is moved through the at least one air-to-air heat exchanger for the purpose of extracting heat.
4 . The air cooling device according to claim 1 , wherein the pre-cooler located in the secondary air flow path is a direct evaporative cooler.
5 . The air cooling device according to claim 1 , wherein the refrigeration condenser/heat rejection coil serves to reject heat from the auxiliary refrigeration cooling system.
6 . The air cooling device according to claim 1 , further comprising a refrigeration evaporator/cooling coil in the primary recirculation air flow path between an outlet side of the air-to-air heat exchanger and the supply outlet.
7 . The air cooling device according to claim 1 , further comprising back-draft dampers on the at least one scavenger air fan, when the at least one scavenger air fan comprises a plurality of scavenger fans.
8 . The air cooling device according to claim 1 , further comprising back-draft dampers on the at least one condenser fan, when the at least one condenser fans comprises a plurality of condenser fans.
9 . The air cooling device according to claim 1 , wherein the temperature at which the recirculation supply air exits the air cooling device is controlled by adjusting an air flow rate in the secondary outdoor air flow path.
10 . The air cooling device according to claim 1 , wherein the temperature at which the recirculation supply air exits the air cooling device is controlled by staging or modulating refrigeration based supplemental cooling when the scavenger air flowing through the secondary outdoor air flow path through the at least one air-to-air heat exchanger is insufficient to extract all of the heat required.
11 . The air cooling device according to claim 1 , wherein an air-to-air heat exchange process and an active refrigeration process are operated completely independently of one another.
12 . The air cooling device according to claim 1 , wherein the at least one scavenger air fan is a variable speed fan, and the secondary outdoor air flow is adjusted by varying the speed of the at least one variable speed scavenger air fan.
13 . The air cooling device according to claim 1 , wherein the at least one scavenger air fan is a plurality of scavenger air fans, and the secondary outdoor air flow is adjusted by cycling on and off at least one of the plurality of scavenger air fans to achieve optimal efficiency in concert with modulating the speed of at least one other of the plurality of scavenger air fans operating to reject the heat.
14 . The air cooling device according to claim 1 , wherein the at least one air-to-air heat exchanger comprises at least one of the following:
a) a vertical or horizontally arranged dual cross-flow plate-type heat exchanger,
b) a counterflow plate-type heat exchanger, or
c) a horizontal or vertical heat pipe heat exchanger.
15 . The air cooling device, according to claim 1 , wherein the secondary air flow pre-cooler provides advantage for rejecting heat from the primary airflow through the air-to-air heat exchanger(s) and the refrigeration condenser.
16 . The air cooling device according to claim 1 , wherein the air-to-air heat exchanger is at least one of constructed of polymer tubes, polymer plates, or metallic plates.
17 . The air cooling device according to claim 16 , further comprising:
an additional water spray manifold, and
mist eliminator to facilitate spraying an evaporating water film onto the exterior of the polymer tubing in the air-to-air heat exchanger.
18 . The air cooling device according to claim 17 , wherein moist scavenger air leaving the heat exchanger is used to reject heat from the condenser coil.
19 . The air cooling device according to claim 17 , wherein the at least one air-to-air heat exchanger can be operated dry.
20 . The air cooling device according to claim 1 , wherein the at least one air-to-air heat exchanger can be operated dry, without use of evaporative cooling means.