Patent Application
20080153409
Static air blenders or mixers are well known in the art. Examples of these may be found for example, in U.S. Pat. Nos. 5,632,675 4,495,858, and 6,595,848. In common, they all use a series of fixed vanes forming flow louvers therebetween. The two latter patents use vanes that radiate radially from a central portion of a flow path while the first mentioned patent apparently uses parallel vanes providing flow louvers therebetween. Some of the vanes are pitched at an angle to effect deflection of the air flowing thereby to give the air flow a lateral or sideways component of movement downstream of the vanes. The function of such devices is to effect mixing of a gas typically air, as it flows from an upstream side of the mixer to a downstream side of the mixer. Often times, the incoming air is from a plurality of streams or sources, for example, a return air stream and an outdoor or fresh air stream in an air handling system, as for example, those air handling systems used in commercial air conditioning systems.
While such devices are somewhat effective in mixing air, they do have drawbacks. For example, most duct work in which the mixing systems are installed, is rectangular. One style of mixing device uses a radially radiating vane configuration which leaves zones within rectangular duct work that are outside of the tips of the vanes. To ensure mixing flow in these zones, additional vanes are added outside of the perimeter of the centrally located radiating vanes, see, e.g., U.S. Pat. No. 6,595,848. Support for the radiating vanes to keep them from bending under the influence of the flowing air, can require extra material within the vanes because of their long length to reach the edges of the ducts. If the vanes are self supporting, the vane width may need to be large, increasing the cost to construct the vane assembly.
It is well known that for laminar flow, the flow speed of the air varies by decreasing from the center of the duct outwardly. In theory, in a round pipe, the flow velocity profile for laminar flow is that of a parabola applying further load on the central portion of the vane assembly because of the increased speed of the air at the center.
In air handling units bringing two streams of air together for mixing, one stream may have a greater volume of flow than the other. Additionally the ducts that discharge streams of air into the chamber immediately preceding the air mixer are smaller in cross-section than the chamber. These two factors can result in the stream with greater flow volume dominating the central region of flow with the stream having lesser flow volume filling in around the perimeter. Mixers with radially radiating vanes arranged in two regions of the mixer, a central region and another in the perimeter, will induce vortex airflow in one sense (e.g., clockwise) with the radiating vanes in the central region and in the opposite sense (e.g., counter-clockwise) in the region of the outer perimeter with the perimeter vanes. Although mixing can occur as described above in certain circumstances, this arrangement is not ideal for thorough mixing.
The present invention involves the provision of an air mixing system that includes an airflow inducing device such as an air pump which can be in the form of a bladed fan or a cage blower or any other suitable air pump. The air pump is operable to induce airflow within a duct system including at least one duct. The duct system is operable to conduct flow of air to an enclosure such as a room. An air mixing system is provided that is associated with the duct and is operable to mix air flowing through or to the duct. The mixing system includes at least one mixing device having a plurality of generally rectangular louver systems in which each louver system has at least two vanes defining the louver(s) therein. Each vane has a leading edge and a trailing edge and a respective deflection surface therebetween. At least two of the louver systems in a mixing system direct air flowing to an exit side of the mixing system toward a laterally immediately adjacent louver system to induce vortex airflow on the exit side about a central axis of adjacent louver systems.
The invention also involves the provision of an air mixing system that includes a plurality of separate air feeds and an air discharge. An air pump is provided to effect movement of air through at least one of the air feeds and the discharge. A mixing system is provided and is associated with an air pump positioned flow wise between the discharge and at least one of the air feeds. The mixing system includes a generally rectangular array of a plurality of louver systems. The louver systems are arranged in a plurality of rows and columns. Each of the louver systems has a plurality of vanes and each of the vanes has a leading edge and trailing edge with a respective deflection surface therebetween. The deflection surface is preferably curved and concave in the general direction of airflow through the mixing system. Adjacent vanes in each of the louver systems define the louvers therebetween. The longitudinal axes of the vanes in one louver system are generally normal to the longitudinal axes of the vanes in a laterally immediately adjacent louver system to induce vortex airflow in the discharge. The louver systems form a generally pinwheel arrangement without the vanes being in a radially extending pattern.
Like numbers throughout the various Figures designate like or similar parts and/or construction.
The reference numeral 1 designates generally an air mixer system that is operable to mix air from at least one air source and preferably a plurality of air sources 2, 3. The air sources 2, 3 can be, e.g., a fresh air feed 2 and a return air feed 3. Additional air feeds may be provided as desired. The air mixer system 1 includes at least one duct system designated generally 4 which can be a single duct or a plurality of ducts 5 connecting sources 2, 3 to an enclosure designated generally 7 which can be in the form of one or more rooms 9 in a building 8. A suitable air pump 6, such as a fan or blower is associated with the duct system 4 to induce air flow therein. The air feeds 2, 3 preferably include the ducts 5A-C, each one being connected to a respective source of air. In the illustrated structure, the feed 2 opens to the exterior of the enclosure to allow the inflow of fresh inlet air and the feed 3 is connected to a room 9 of the enclosure 7 to permit return airflow from the enclosure to a mixing device 11 for mixing with fresh inlet air. Typically, the enclosure 7 will have sufficient air leakage, either intentional or unintentional, to permit the desired amount of inlet air to be fed into the enclosure 7 and room 9.
In the illustrated structure, the mixing system 1 includes the mixing device 11 that includes a plurality of rows and columns of generally rectangular flow openings 13 within a frame 10. The frame 10 is preferably attachable to one or more of the ducts, e.g., the duct 5C. The frame has sidewalls 12A-D. The walls 12A-D may also be used to secure the mixing device 11 into the duct system 4. In the air mixing system 1 of
Each louver system 14 includes a plurality of vanes 17. The vanes 17 in each louver system 14 are arranged in generally parallel relationship and are disposed relative to the longitudinal axis A of the mixing device 11 to turn the incoming air from a infeed side 18 and direct it as desired preferably to form a vortex flow on the downstream or outfeed side 19 of the static mixer 11. The angle of inclination B from the longitudinal axis A, is best seen in
One or more brace structures are provided, as best seen in
The louver systems 14 are arranged in rectangular arrays in the frame 10 with the louver systems 14 being positioned in rows and columns which are preferably horizontally and vertically configured. The vanes 17 in each louver system 14 have their longitudinal axes generally parallel and have their surfaces 23 spaced from adjacent vanes 17 defining louvers 33 therebetween for gas to flow through. As shown, the louvers 33 are generally rectangular. The longitudinal axes of vanes 17 in one louver system 14 are generally normal to the longitudinal axes of vanes in at least one immediately adjacent louver system. For example, as best seen in
As shown, the vanes 17 in each louver system 14 have their longitudinal axes generally parallel, the deflection surfaces 23 generally concentric and the planes P extending between their leading and trailing edges 21, 22, respectively, also generally parallel. However, variations may be provided to suit a specific need in a specific system. For example, the vanes 17 in a louver system may each have a different angle B of inclination. The louvers 33 between the vanes 17 are generally rectangular in shape and the flow paths or louvers 33 between the vanes 17 are directed toward an immediately adjacent louver system (non diagonal) to effect vortex flow and mixing of the fluid flowing through the mixing device 11. The air flowing through the device 11 mixes on the downstream side 19 and if the duct 5A is long enough and the flow of the air is sufficiently slow, non turbulent or laminar flow may again be achieved in the duct 5C at some point downstream of the mixing device 11. However, turbulent flow is desired at least immediately adjacent the downstream side 19 of the mixing device 11. The walls 37 of the brace members 32 divide the flow path through the mixer 11 into a plurality of distinct or separate generally rectangular flow paths.
It has been found that the width of the vanes is on the order of between about 4 and about 6 inches and preferably the length of the vanes is in the range of between about 6 inches and about 20 inches. The curvature of the deflection surfaces 23 is on the order of an approximate radius in the range of between about 3 inches and about 7 inches. The ratio of radius of curvature to chord length is preferably in the range of between about 0.8 and about 1.2. In a preferred embodiment, the vanes 17 can be extruded providing a generally uniform transverse cross sectional shape along the length thereof. The vanes 17 may be extruded from a polymeric material or a metallic material.
Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.
