US20100255768A1

US20100255768A1 - Airflow economizer and method for operating the same

Info

Publication number: US20100255768A1
Application number: US12/755,865
Authority: US
Inventors: Kevin J. Porter
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2009-04-07
Filing date: 2010-04-07
Publication date: 2010-10-07
Also published as: CN101858639A

Abstract

An economizer, and a method for operating the same, is provided having a housing with external airflow section and an internal airflow section. The external airflow section includes one or more external flow blades mounted in an external airflow path. The external flow blades are selectively rotatable between an open position and a substantially closed position. The internal airflow section includes one or more internal flow blades mounted in an internal airflow path. The internal flow blades are selectively rotatable between an open position and a substantially closed position. Each internal flow blade includes a leading portion. The leading portion of each internal flow blade is substantially parallel to the internal airflow path when the internal flow blades are disposed in the open position. The external flow blades and the internal flow blades are linked together such that when the internal flow blades are in the open position, the external flow blades are in the substantially closed position, and when the internal flow blades are in the substantially closed position, the external flow blades are in the open position.

Description

This application claims priority to U.S. Provisional Appln. No. 61/167,384 filed Apr. 7, 2009, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Technical Field
The present disclosure relates generally to airflow heating and cooling systems and, more particularly, to such systems that use an economizer operable to mix recycled air with external air.
2. Background Information
Many modern buildings utilize heating and cooling systems to regulate internal ambient conditions such as temperature, humidity and oxygen content. The ambient conditions may be regulated by circulating a mixture of outdoor/exterior air and indoor/interior air. For example, outdoor air may be used to cool an interior space of a building where the outdoor air is cooler than air circulating within the building. This may save energy costs associated with air conditioning the warmer indoor air.
Typically, heating and cooling systems incorporate economizers to regulate the mixture of outdoor and indoor air to reduce energy consumption. As known in the art, an economizer is a mechanical device connected to a plurality of ducts in a heating and cooling system for regulating the mixture of outdoor air and indoor air (sometime referred to as “circulated air”) circulated into the building. For example, where the ambient temperature inside the building is higher than an upper set point and the outside air is sufficiently cool, the economizer may increase the percentage of cooler outside air and decrease the percentage of warmer indoor air in the mixture circulated into the building. Conversely, where the ambient temperature inside the building is lower than a lower set point, the economizer may decrease the percentage of cooler outside air and increase the percentage of warmer indoor air in the mixture circulated into the building.
The efficiency of the economizer and therefore the heating and cooling system is correlated to the internal flow characteristics of the economizer. For example, the greater the pressure drop across the economizer, the lower the efficiency is for the economizer and the heating and cooling system.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present invention, an economizer is provided having a housing with external airflow section and an internal airflow section. The external airflow section includes one or more external flow blades mounted in an external airflow path. The external flow blades are selectively rotatable between an open position and a substantially closed position. The internal airflow section includes one or more internal flow blades mounted in an internal airflow path. The internal flow blades are selectively rotatable between an open position and a substantially closed position. Each internal flow blade includes a leading portion. The leading portion of each internal flow blade is substantially parallel to the internal airflow path when the internal flow blades are disposed in the open position. The external flow blades and the internal flow blades are linked together such that when the internal flow blades are in the open position, the external flow blades are in the substantially closed position, and when the internal flow blades are in the substantially closed position, the external flow blades are in the open position.
According to another aspect of the present invention, a method for operating an economizer is provided. The method comprises the steps of: a) providing a housing having an external airflow section with one or more external flow blades rotatably mounted in an external airflow path, which external flow blades are operable to be positioned in an open position where the external airflow path is open and a substantially closed position where the external airflow path is substantially closed, and an internal airflow section with one or more internal flow blades rotatably mounted in an internal airflow path, which internal flow blades are operable to be positioned in an open position where the internal airflow path is open and a substantially closed position where the internal airflow path is substantially closed, wherein each internal flow blade includes a leading portion, and in the internal flow blade open position the leading portion of each internal flow blade is substantially parallel to the internal airflow path; b) rotating one or more external flow blade gears between an open position and a substantially closed position to vary a quantity of an outdoor airflow traveling through the external airflow path; and c) rotating one or more interior flow blade gears proportionally to the external flow blade gears, and thereby rotating the interior flow blade gears between a substantially closed position and an open position to vary a quantity of an indoor airflow traveling through the internal airflow path. The quantity of the outdoor airflow is inversely related to the quantity of indoor airflow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic illustration of one embodiment of an economizer in a first configuration.

FIG. 2 is a diagrammatic illustration of the economizer in a second configuration.

FIG. 3 is a diagrammatic illustration of the economizer in a third configuration.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 3 are a diagrammatic illustration of one embodiment of an economizer 100 for regulating the mixture of an airflow. The economizer 100 includes a housing 8 with an external airflow section 10 and an internal airflow section 12, and a linkage assembly. The external airflow section includes one or more external flow blades 14, and the internal airflow section includes one or more internal flow blades 16. In some embodiments, the economizer 100 further includes one or more exhaust dampers 60.
The external airflow section 10 has an external airflow path 18 extending from an airflow inlet 20 to an airflow outlet 22. The external airflow section 10 further includes a first sealing surface 24 and a second sealing surface 26, which surfaces extend into the external airflow path 18.
Each external flow blade 14 has a length extending between a first end 28 and a second end 30, where the length of the blade has a surface area and the ends 28, 30 of the blade have a surface area. Each external flow blade 14 further includes a leading portion 31 and a trailing portion 33.
The internal airflow section 12 has an internal airflow path 32 extending from an airflow inlet 34 to an airflow outlet 36. In the embodiments shown in FIGS. 1-3, the internal airflow section 12 includes an airflow exhaust 40 that selectively provides an airflow exhaust path 38 (see FIG. 2) extending between the airflow inlet 34 and an airflow exhaust 40. In FIGS. 1-3, the airflow exhaust is shown shut, and in FIG. 2 the airflow exhaust 40 is shown open in phantom. The internal airflow section 12 further includes a first sealing surface 42 and a second sealing surface 44, which surfaces extend into the internal airflow path 32.
Each internal flow blade 16 has a length extending between a first end 46 and a second end 48, where the length of the blade has a surface area and the ends 46, 48 of the blade have a surface area. Each internal flow blade 16 further includes a leading portion 49 and a trailing portion 51.
The linkage assembly links together and synchronizes movement of the external flow blades 14 and the external flow blades 16. For example, in the embodiment illustrated in FIGS. 1-3, the linkage assembly includes one or more external flow blade gears 50, one or more internal flow blade gears 52, one or more linkage gears 54 and one or more idler gears 56. The gears in the linkage assembly are configured as, but not limited to, spur or helical gears. Each external flow blade gear 50 is configured to mesh with the one or more adjacent external flow blade gears 50. “Mesh” is used to describe an interaction between gears such that one meshed gear propels and rotates an adjacent meshed gear. The linkage gear 54 is configured to mesh with one of the external flow blade gears 50 and one of the internal flow blade gears 52. Each idler gear 56 is configured to mesh with two of the internal flow blade gears 52, where adjacent internal flow blade gears 52 do not mesh together. The external flow blade gears 50, the internal flow blade gears 52, the linkage gear 54 and the idler gears 56 are sized such that the linkage gear 54 links the internal and external flow blade gears 52 in a 2:1 gear ratio, although not limited thereby. That is, for every two degrees each external flow blade gear 50 rotates, each internal flow blade gear 52 rotates one degree. For example, each external flow blade gear 50 is sized having a diameter, each internal flow blade gear 52 is sized having a diameter equal to twice the diameter of the external flow blade gears 50, and the linkage gear 54 and each idler gear 56 are sized having diameters equal to the diameter of the external flow blade gears 50. The linkage assembly is further configured to synchronize the internal flow blade gears 52 such that each internal flow blade gear 52 rotates in a similar manner (i.e., clockwise or counter clockwise manner). That is, where one of the idler gears 56 rotates in a clockwise manner, the two meshed internal flow blade gears 52 rotate in a counter clockwise manner. It should be noted that the aforesaid example is only one embodiment of the linkage assembly and the present invention is not limited to this particular embodiment. For example, in some embodiments, the linkage assembly may use a system of pulleys/levels and belts/ropes instead of, or in addition to, a system of gears. Further, depending on design requirements, the idler gears 56 may be partially or completely omitted. In an alternate embodiment, the linkage assembly may include a plurality of actuators (not shown) to link and synchronize the external flow blades 14 and the internal flow blades 16. For example, in one embodiment, the actuators can be configured in communication with a processor (not shown) such that each actuator is operable to rotate one of the external flow blades 14 or one of the internal flow blades 16 according to a synchronized command signal communicated from the processor.
The external airflow section 10 and the internal airflow section 12 of the housing 8 are configured to define a partition 58 extending at least partially therebetween. The partition 58 fluidly separates the external airflow path 18 in the external airflow section 10 from the internal airflow path 32 and the airflow exhaust path 38 in the internal airflow section 12, and vice versa.
The external flow blades 14 are attached to the external flow blade gears 50 which are mounted in the external airflow path 18 and are selectively rotatable between an open position where the external airflow path 18 is at a maximum, extending through the external airflow section 10 and a substantially closed where the external airflow path 18 is at a minimum, extending through the external airflow section 10. In the open position (as shown in FIG. 2), at least the leading portion 31 of each external flow blade 14 is substantially parallel to the external airflow path 18. In the closed position (as shown in FIG. 1), the external flow blades 14 are rotated into contact with the first sealing surface 24 and the second sealing surface 26 in the external airflow section 10. In this position, the length of each external flow blade 14 is disposed substantially perpendicular to the external airflow path 18, thereby closing the airflow path 18.
The internal flow blades 16 are attached to the internal flow blade gears 52 which are mounted in the internal airflow path 32 and are selectively rotatable between an open position where the internal airflow path 32 is open and a substantially closed position where the internal airflow path 32 is substantially closed. In the open position (as shown in FIG. 1), at least the leading portion 49 of each internal flow blade 16 is substantially parallel to the internal airflow path 32 and the airflow path 32 is open. In the substantially closed position (as shown in FIG. 2), the internal flow blades 16 are rotated in contact with the third sealing surface 42 and the fourth sealing surface 44. In the substantially closed position, the length of each internal flow blade 16 is acutely orientated to the internal airflow path 32, for example, at forty-five degrees (45°), and the airflow path 32 is closed.
The linkage assembly is configured to link the internal and external flow blades 14, 16 such that rotational movement of one, results in rotational movement of the other. For example, the linkage gear 54 and the idler gears 56 are rotatably mounted to the external and internal airflow sections 10, 12 of the housing 8. As previously described, the gears in the linkage assembly are meshed together such that as one gear rotates, each of the gears in the assembly rotates according to a predetermined ratio (e.g. 2 to 1) and manner (e.g. clockwise or counter clockwise). The linkage assembly is further configured to synchronize the external and internal flow blade gears 50, 52 such that when the internal flow blades 16 are disposed in the fully open position, the external flow blades 14 are disposed in the closed position. Further, the idler gears 56 are configured to align the internal flow blade gears 52 such that each internal flow blade 16 has a similar spatial orientation. That is, the internal flow blade gears 52 are aligned such that each internal flow blade 16 is disposed at an angle “θ” relative to the internal airflow path 32 (see FIG. 3).
The exhaust dampers 60 are pivotally mounted in an end to end configuration along the airflow exhaust in the internal airflow section 12 and are operable to substantially close the airflow exhaust path 38.
Referring to FIG. 3, during operation of the economizer 100 the external and internal flow blades 14, 16 are selectively rotated to inversely regulate quantities of an outdoor (non-circulated) airflow 62 traveling through the external airflow path 18 and an indoor (circulated) airflow 64 traveling through the internal airflow path 32. That is, where the external flow blades 14 permit a relatively high percentage of the outdoor airflow 62 to travel through the external airflow path 18, the internal flow blades 16 permit a relatively low percentage of the indoor airflow 62 to travel through the internal airflow path 32.
In the configuration illustrated in FIG. 1, for example, substantially no outdoor airflow 62 travels through the external airflow path 18 and into the building because the external flow blades 14 are in the closed position. Substantially all of the indoor airflow 64, in contrast, travels through the internal airflow path 32 and recirculates back into the building because the internal flow blades 16 are in the fully open position. In the configuration illustrated in FIG. 2, a maximum amount of outdoor airflow 62 enters the building through the external airflow path 18 when the external flow blades 14 are in the fully open position. At the same time, substantially no indoor airflow 64 travels through the internal airflow path 32 because the internal flow blades 16 are in the closed position. In this configuration, the indoor airflow 64 may exit the building by following the airflow exhaust path 38 through the internal airflow section 12 and out the exhaust dampers 60. In the configuration illustrated in FIG. 3, a percentage of maximum outdoor airflow 62 enters through the external airflow path 18 where the external flow blades 14 are in a partially closed position. At the same time, a percentage of the maximum recirculating indoor airflow 64 travels through the internal airflow path 32 where the internal flow blades 16 are in a partially open position. In this configuration, some percentage of the indoor airflow 64 which does not travel through the internal airflow path 32, may exit through the exhaust dampers 60.
It should be noted that the efficiency of the economizer 100 and the heating and cooling system is in part a function of a pressure drop between the airflow inlet 20 and outlet 22 in the external airflow section 10 and a pressure drop between the airflow inlet 34 and outlet 36 in the internal airflow section 12. The pressure drops through the external and internal airflow sections 10, 12 correlate in part to the positioning and therefore the surface area of each blade directly exposed to the outdoor or indoor airflows. For example, the internal flow blades 16 induce a relatively small pressure drop in the fully open position where at least the leading portions 49 of the blades 16 are parallel to the internal airflow path 32 such that the indoor airflow 64 impinges only the end edge surface of each blade 16 when traveling through the internal airflow path 32. In contrast, some prior art economizers are subject to a relatively large pressure drop in the fully open position where the blades are positioned acutely (e.g. at a 45° angle) to an airflow path. In the forty-five degree (45°) orientation, the flow impinges on a substantial area of the blades and creates an undesirable pressure drop.
While various embodiments of the present invention have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the present invention is not to be restricted except in light of the attached claims and their equivalents.

Claims

1. An economizer, comprising:

a housing having an external airflow section that includes one or more external flow blades mounted in an external airflow path, which external flow blades are selectively rotatable between an open position and a substantially closed position, and an internal airflow section that includes one or more internal flow blades mounted in an internal airflow path, which internal flow blades are selectively rotatable between an open position and a substantially closed position, wherein each internal flow blade includes a leading portion;

wherein the leading portion of each internal flow blade is substantially parallel to the internal airflow path when the internal flow blades are disposed in the open position; and

wherein the external flow blades and the internal flow blades are linked together such that when the internal flow blades are in the open position, the external flow blades are in the substantially closed position, and when the internal flow blades are in the substantially closed position, the external flow blades are in the open position.

2. The economizer of claim 1, further comprising a linkage assembly proportionally linking the external flow blades to the internal flow blades such that the external flow blades each rotate two degrees for every one degree the internal flow blades rotate.

3. The economizer of claim 2, where the external flow blades are rotatable approximately ninety degrees between the open position and the substantially closed position, and the internal flow blades are rotatable approximately forty five degrees between the open position and substantially closed position.

4. The economizer of claim 2, where the linkage assembly comprises at least one linkage gear, at least one external flow blade gear and at least one internal flow blade gear, wherein each the external flow blade gear is attached to one of the external flow blades, each internal flow blade gear is attached to one of the internal flow blades, and the linkage gear is in mesh with the external flow blade gear and internal flow blade gear.

5. The economizer of claim 4, where the external airflow section has a plurality of external flow blades each attached to an external flow blade gear, and where the internal airflow section has a plurality of internal flow blades each attached to an internal flow blade gear.

6. The economizer of claim 5, where the linkage assembly further comprises at least one idler gear linking the internal flow blade gears.

7. The economizer of claim 6, where the external airflow path extends between a first airflow inlet and a first airflow outlet, and where the internal airflow path extends between a second airflow inlet and a second airflow outlet.

8. The economizer of claim 7, where the internal flow blades are substantially perpendicular to the second airflow inlet when the internal flow blades are in the open position.

9. The economizer of claim 2, where the linkage assembly comprises a plurality of actuators in communication with a processor, where each actuator is coupled to one of the external flow blades or one of the internal flow blades and operational to rotate the blade between the open and the closed positions.

10. The economizer of claim 2, where the internal airflow section further comprises at least one exhaust damper pivotally mounted in an airflow exhaust path, which damper is operable to open or close the airflow exhaust path.

11. The economizer of claim 10, where the airflow exhaust path extends from the second airflow inlet to an airflow exhaust.

12. The economizer of claim 2, wherein the external airflow section is configured to regulate an outdoor airflow, and wherein the internal airflow section is configured to regulate an indoor airflow.

13. A method for operating an economizer, comprising the steps of:

providing a housing having an external airflow section with one or more external flow blades rotatably mounted in an external airflow path, which external flow blades are operable to be positioned in an open position where the external airflow path is open and a substantially closed position where the external airflow path is substantially closed, and an internal airflow section with one or more internal flow blades rotatably mounted in an internal airflow path, which internal flow blades are operable to be positioned in an open position where the internal airflow path is open and a substantially closed position where the internal airflow path is substantially closed, wherein each internal flow blade includes a leading portion, and in the internal flow blade open position the leading portion of each internal flow blade is substantially parallel to the internal airflow path;

rotating one or more external flow blade gears between an open position and a substantially closed position to vary a quantity of an outdoor airflow traveling through the external airflow path; and

rotating one or more interior flow blade gears proportionally to the external flow blade gears, and thereby rotating the interior flow blade gears between a substantially closed position and an open position to vary a quantity of an indoor airflow traveling through the internal airflow path;

wherein the quantity of the outdoor airflow is inversely related to the quantity of indoor airflow.

14. The method of claim 13, further comprising the step of providing a linkage assembly linking the external flow blades to the internal flow blades.

15. The method of claim 14, where the external flow blades are rotated two degrees for every one degree the internal flow blades are rotated.

16. The method of claim 15, where the internal airflow section further includes at least one damper pivotally mounted in an airflow exhaust path, which damper is operable to open or close the airflow exhaust path.