US3911804A

US3911804A - Air mixing device

Info

Publication number: US3911804A
Application number: US471213A
Authority: US
Inventors: William K Y Tao
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-05-20
Filing date: 1974-05-20
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14

Abstract

An air mixing device comprising a casing having a cool or outside air inlet at its front side and a warm or recirculated air inlet at the upper end thereof. There are a plurality of ducts extending from front to rear of the casing with their forward and rearward ends opening respectively through the front and rear walls of said casing. Between the forward ends of the ducts the front wall is imperforate while the corresponding portion of the rear wall is perforated, with the openings thereof being substantially less than the diameter of the ducts. The front and rear walls are contoured to include inwardly tapering recesses communicating with the proximate end of the related duct for directing air flow. Each of said ducts is provided with a longitudinal slot-like opening for effecting a communication between the ducts and the interior of the casing for intermixture of the incoming air. The casing may be provided with acoustically absorbing material for sound attenuation.

Description

United States Patent 1191 Tao [4 1 Oct. 14, 1975 ['5 AIR MIXING DEVICE Primary ExandinerWilliam 1-:v Wayner [7 6] lnventor: William K. Y. Tao, 9960 Holliston Assistant Examl'1er Henry Yuen Court st Louis MO 63124 Attorney, Agent, or Fzrm-Ralph A. Kallsh [22] Filed: May 20, 1974 ABSTRACT [21] Appl. No.: 471,213 An air mixing device comprising a casing having a 7 cool or outside air inlet at its front side and a warm or [52] US. Cl 98/38 A; 259/4; 137/604; recirculated air inlet at the upper end thereof. There 98/38 B are a plurality of ducts extending from front to rear of [51] Int. Cl. B01F 15/00; F24F 7/00 the ca ing wi h heir forward and rearward ends open- [58] Field of Search 98/38 B, 37, 38 E, 13, ing respectively through the front and rear walls of 98/1 16, 40 C, 38 A; 261/21 23 R; 165/19, said casing. Between the forward ends of the ducts the 59; 137/604; 259/4; 239/434 front wall is imperforate while the corresponding portion of the rear wall is perforated, with the openings [56] Referen e Cit d thereof being substantially less than the diameter of UNITED STATES PATENTS the ducts. The front and rear walls are contoured to include inwardly tapering recesses communicating g i with the proximate end of the related duct for direct- 2 793 812 5 1957 MCSAAQAIIIIIIIIIIIIIIIII .11: 98/38 B ing air Each of Said ducts is Provided with a 3,272,427 9/1966 valentinem 98/38 B gitudinal slot-like opening for effecting a communica- 3,318,225 5 1967 May 98/38 B tion tw n th ucts and the nterior of the Casing FOREIGN PATENTS OR APPLICATIONS for intermixture of the incoming air. The casing may 57] 825 M958 1 l 923/40 C be provided with acoustically absorbing material for ta y 1,026,986 4/1966 United Kingdo 98/40 c Sound attenuauon 16 Claims, 5 Drawing Figures I 2! 8 o v 7 0 00 l o o o J l /3 J I I I J 1 1 J I? Z 4- ,43 g l U o ozl l llllrll US. Patent Oct. 14,1975 I Sheet1of3 3,911,804

U.S. Patent 0a. 14, 1975 Sheet 2 of 3 3,911,804

FIG.3 7

US. Patent Oct. 14, 1975 Sheet 3 of3 3,911,804

FIG. 5

AIR MIXING DEVICE BACKGROUND AND SUMMARY OF THE INVENTION This invention relates in general to heating and air conditioning systems as utilized for ventilation and temperature maintenance in buildings and, more particularly, to an air mixing device therefor.

Heretofore, various efforts have been made to develop means for mixing the recycled, warmer, or room air with fresh, cooler, outside air prior to the introduction of the air mixture to heating and air conditioning systems. However, such efforts have not proved fully efficacious. Such prior structures have consistently embodied a relatively enlarged open chamber into which the recirculated air and the outside air are received; customarily there may be a substantial differential between the admitted air bodies, as in winter the outside air may be as cold -l to F. while the recirculated or room air is normally between 65 to 80F. With conventional air conditioning mixing boxes, louvered dampers, which may be motor controlled, are provided at their respective entrances into such chambers whereby the operation of the same will permit desired amounts of outside air and room air to enter the chamber. Such dampers are designed to fragment the incoming air as well as affect the direction of flow for conducing to intermixture. However, it has been found that in such systems the air tends to stagnate within the chamber with the flow becoming laminated; with the cold, outside air tending to remain at the bottom of the chamber and the hot, room air rising to the top thereof. Thus, uniformity of temperature is not achieved and undesired stratification results. Air emitted from the chamber is not properly mixed so that the same presents a potential damage to any heating or cooling coils containing water or steam over which such air may pass. The cold air within the laminated flow may freeze the water or steam thereby interrupting the flow within the coil and causing disfunction of the system. As is well known, a frozen coil may crack due to the expansion of the contained water so that upon thawing water will leak from the coil into the unit and into surrounding areas, such as floors, walls, and the like, causing severe damage. Thus, homogeneous mixture of the air is desired, eliminating laminated flow to avoid the aforementioned hazards.

Another expedient currently used in a fruitless effort to effect mixture of the air bodies is the provision of radially positioned turbine blades, as mounted within rings, within the chamber outlet; the said blades being spirally pivoted relative to the axis of the air stream passing through the rings so as to impart a circumferential whirling to the stream. But in this arrangement there is a substantial pressure drop through the system since the outlet must be relatively limited in order to develop the whirling or rotating action before emission and thus the air is made turbulent with the consumption of energy. It has been found that the whirling action does not bring about the degree, of intermixture requisite for uniformity of temperature and, hence, of the composition of the delivered air. Furthermore, in this type of system because of the pressure loss the fan which draws air through the ventilation ducts requires substantial power so that a displeasing noise level is reached by virtue of the operation of the fan and the developed air turbulence.

, 2 An additionalv attempt for air intermixture has been through the medium of relatively large baffle boxes, but here again, the results have been wholly unsatisfactory and with the space requirements being too great for the average building.

Therefore, it is an object of the present invention to provide an air mixing device which embodies novel means located within an air chamber to effect a thorough intermixture of recirculated air and the outside air to present uniform temperature and composition of the air discharged from the device for reception by the customary coils.

It is another object of the present invention to provide an air mixing device of the character stated which does not incorporate moving parts thereby simplifying production as well as obviating the services of skilled personnel as would be required for adjusting blade dampers, cyclonic whirling units, and the like.

It is a further object of the present invention to provide an air mixing device of the character stated which is peculiarly adapted for modular construction whereby any preselected number of such modules may be'integrated for coordination with the particular filter bank of the system; said modules being adapted for growing in either a vertical or horizontal direction, or in both directions, whereby a marked versatility is provided.

It is an additional object of the present invention to provide an air mixing device of the character stated which substantially eliminates laminated flow and thereby obviates the likelihood of coil freezing with resultant water damage and air conditioning interruption.

It is another object of the present invention to provide an air mixing device which causes minimal pressure drop with consequent minimal energy loss so that most substantial efficiency is achieved by operation of such device.

It is a still further object of the present invention to provide an intermixing device which may be easily installed in existing systems; which is durable and reliable in usage; which is of marked simplicity in design so as to be resistant to malfunction; and which is most economical in production.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now by reference characters to the drawingswhich illustrate the preferred embodiment of the present invention, A designates an air mixing device for incorporation withinan air conditioning system and is shown, for purposes of illustration, as being of substantially square form having parallel front and rear walls 1,2,

side walls

3,4, a bottom wall 5, and being open at its upper end, at 6, to define a warm or room air inlet; there being a flange 7 at such upper end for connection to an warm air conduit (not shown). Front wall 1 also embodies a flange 8 for Connection to an outside air conduit (not shown). Said front wall 1 is formed, preferably integrally, as by molding from synthetic material of inwardly tapering recesses 9, of general funnel shape, the inner ends of which terminate in a short constant-diameter neck 10. The said necks 10 are each received within the forward end portion of a duct 11 as of annular cross section which extends throughout the length of device A, that is from front wall 1 to rear wall 2. A suitable fastener, such as a screw or the like, may be utilized for interengaging necks l and the related ducts 11. Although the number of ducts 11 would manifestly depend upon the overall dimensions of device A, for exposition only, device A is illustrated as incorporating nine such ducts arranged in three horizontal rows or banks of three. It will be seen that recesses 9 which flare outwardly from the associated duct 11 serve to direct air into said ducts 11 substantially eliminating turbulence and thus conducing to a streamline flow.

Ducts 11 may be constructed of any suitable rigid material, but desirably of such having good sound absorption qualities as for instance, fiberglas, metal with a liner of acoustic material and the like. Thus, each duct 11 comprehends a continuous side wall 12 within which is provided a longitudinal, coextensive slot-like opening 12 for purposes presently appearing. With reference to FIGS. 1, 2, and 3, it will be seen that ducts 11 may be disposed so that the associated openings 12' may openin various directions, developing a relatively random pattern.

Rear wall 2 is of like configuration as front wall 1 having a plurality of inwardly tapering recesses 13, the inner ends of which define a short constant-diameter neck 14 for reception within the rearward end of the related duct 11 and being engaged thereto, as by suitable fasteners. Thus, recesses 13 conduce to smooth flow of the emitted air from device A as toward the usual filter bank and heating and cooling coils located downstream of device A within the particular system.

Rear wall 2 is perforated throughout its extent having a multiplicity of apertures 15 of relatively reduced diameter with respectto ducts 11. The perforated or grill character of rear wall 2 contrasts with front wall 1 which is imperforate or solid except for the bases of recesses 9 which communicate with ducts 11.

Side walls

3,4 and bottom wall (FIG. 1) are unbroken or continuous.

In actual usage, the cool, outside air flows through the outside air conduit (not shown) toward front wall I of device A'and enters the forward ends of ducts 11 through necks of the related recesses 9. Thus, said ducts 11 together with the associated recesses 9, serve to divide the unitary cool air mass into individual, discrete flow components corresponding in number to the number of such ducts. With ducts 11 arranged in selected patterns, as illustrated in FIG. 1, the received cool air is distributed, as it were, within device A in a multiplicity of substantially equal integrants Such distribution conduces to mixing, as will be shown, and obviates the heretofore accepted unequal distribution when the cool air is received within a single enlarged chamber.

The recirculated or warmer air flows into device A through the inlet-forming, open, upper end 6 flowing downwardly within device A and through the pathway defined by the exterior of ductsll for envelopment of the same as the warm air travels toward rear wall 2 for discharge therethrough. By reason of the slot-like openings 12 within each duct 11, there is effected an equalization of the warm, recirculated air, and the cool outside air as the latter may vary in quantity or velocity. If the flow of the cool air is less than that of the warmer recirculated air, the latter will diffuse into ducts 11 through openings 12' thereof for intermixture with the cool air within such ducts which will have the tendency of slowing the velocity of air at the outlet and thus promote better mixing. Conversely, if the flow of the cooler outside air is greater than that of the warmer recirculated air, the cool air will tend to leak through openings 12' and into the volume surrounding such ducts thereby slowing its velocity within the tube and promoting increased mixing within device A. Accordingly, the novel construction of ducts ll serve to bring about an equalization in the relative velocities of the incoming air sources resulting in a substantial homogeneity of the air emitted from device A. Thus, said device is self-balancing as a result of the unique construction of ducts l1 and thereby causes but an extremely limited, very low pressure drop from front wall to rear wall with an attendant extremely low energy loss.

It is also to be observed that the small diameters of openings 15 conduce to the completion of the intermixture as the same provide a nozzle effect forcing the particular air components into increased intimacy. By such intermixture, the temperature of the discharged air is sufficiently above that of the incoming cool air so as to obviate potential hazard to the coils. The novel structure of this invention eliminates the danger of air stratification, bringing about uniformity in composition, as well as in temperature, pressure, and velocity.

Openings 12 in ducts 10 are fundamentally venturilike in character, productive of a smooth, nonturbulent flow. Furthermore, the blending of the two air constituents is brought about in a manner which is substantially non-productive of noise. A fiberglas lining may be provided within device A for promoting acoustical attenuation.

lt will be further observed that perforated rear wall 2 also promotes the dispersal of the mixed air and the continuing of the desired equivalency of distribution within the receiving volume.

The air mixing device A shown in FIG. 1 may be easily modified to constitute a module for integration with a plurality oflike modules for developing a resultant air mixing unit of predetermined volume and configuration; that is, such modules may be unified in a vertical manner, or in. a horizontal manner, or in both. FIG. 6 illustrates a composite air mixing unit being indicated generally at A and being formed of a multiplicity of such devices A so as to have a height at least three such units and a depth of two. It is only required that the

side walls

3,4 and bottom walls 5 be removed where necessary so as to establish communication between the adjacent integrated devices A and with the ducts ll of each of such units being longitudinally aligned with the ducts of the immediately adjacent device A within the same horizontal plane so that from the front or cool air inlet side 21 of unit A said ducts 11 will be continuous lengthwise of said unit A to the rear or discharge side 22 thereof. The operation of unit A is understandably the same as for device A above described but is simply on an increased scale.

Accordingly, device A is of marked versatility by reason of its fundamental modular character so that mixing devices of any predetermined capacity or configuration may be easily achieved in a most economical and reliable manner and with diminution in efficiency.

From the foregoing it is apparent that the device of the present invention demonstrates a manifest advance over aix mixing systems heretofore known. By use of the present invention, air is more thoroughly mixed thereby substantially eliminating the possibility of coil freezing with consequent water damage and system interruption. A singularly low pressure drop is occasioned so that the energy loss is minimal and, clearly, the acoustical properties of device A constitute an improvement in that the noise leval is at a minimum Furthermore, Device A is peculiarly adapted for flexible module design for customized usage.

It is to be understood that if desired the recirculated, warm, or room air inlet may be connected to front wall 1 while the cool, fresh, or outside air inlet may be connected through the upper end 6 of device A. The selection of the location of such inlets would depend upon the preference of the installer. [t is further recognized that the said inlets may be connected to inside and outside sources of air well as to sources within the particular building structure but having the requisite temperature differential.

Having described my invention, what I claim and desire to obtain by Letters Patent is:

1. An air mixing device for use in air conditioning systems comprising means defining a chamber having an upper portion, a lower portion, side portions, and front and rear portions, there being a first air inlet in said upper portion, there being a first air outlet in said rear portion, at least one open-ended duct with a side wall between its ends provided within said chamber and extending from said front portion to said rear portion and opening at its respective ends therethrough, the forward end of said duct constituting a second air inlet, the rearward end of said duct constituting a second air outlet, and said duct having an opening in its side wall between its ends and within said chamber whereby air may flow between said duct and said chamber responsive to differential of pressure between the bodies of air entering said chamber through said first and second air inlets for effecting an equalization of pressure in the air emitted through said first and second air outlets.

2. An air mixing device as defined in claim 1 and further characterized by said duct opening being of elongated slot-like character.

3. An air mixing device as defined in claim 1 and further characterized by said rear portion first air outlet comprising a plurality of apertures.

4. An air mixing device as defined in claim 3 and further characterized by the cross sections of said rear portion apertures being less than the cross section of said duct.

5. An air mixing device as defined in claim 2 and further characterized by said elongated slot-like opening extending longitudinally of said duct and being substantially co-extensive therewith.

6. An air mixing device for use in air conditioning systems comprising means defining a chamber having an upper portion, a lower portion, side portions, and

front and rear portions, there being a first air inlet in said upper portion, there being a first air outlet in said rear portion, a plurality of open-ended ducts each having a side wall between its ends provided within said chamber and extending from said front portion to said rear portion and opening at their respective ends therethrough, the forward ends of said ducts constituting a second air inlet, the rearward ends of said ducts constituting a second air outlet, and each of said ducts having an opening in its side wall between its ends and within said chamber whereby air may flow between said ducts and said chamber responsive to differential of pressures between the bodies of air entering said chamber through said first air inlet and through the forward ends of said ducts for effecting an equalization in pressure in the air being emitted through said first air outlet and said rearward ends of said ducts.

7. An air mixing device as defined in claim 6 and further characterized by the openings in each of said ducts being of elongated slot-like character and extending longitudinally thereof.

8. An air mixing device as defined in claim 7 and further characterized by said first air outlet in said rear portion comprising amultiplicity of apertures between the rearward ends of said ducts.

9. An air mixing device defined in claim 8 and further characterized by said first air outlet apertures being of less cross section than the cross section of said ducts.

10. An air mixing device as defined in claim 6 and further characterized by said ducts being arranged within said chamber for substantial equal distribution therethrough, said ducts being spaced from each other to provide air flow paths between and about same.

11. An air mixing device as defined in claim 6 and further characterized by said chamber front portion being imperforate between the forward ends of said ducts.

12. An air mixing device as defined in claim 11 and further characterized by said imperforate front portion having a plurality of inwardly and rearwardly tapering recesses corresponding in number to said ducts and communicating at their inner rearward ends with the forward ends of said ducts.

13. An air mixing device as defined in claim 6 and further characterized by said chamber rear portion being a wall, said wall being provided with a plurality of inwardly tapering, forwardly extending recesses corresponding in number to the ducts and communicating at their forward ends with the rearward ends of said ducts, said wall being perforated between said ducts to provide a plurality of apertures constituting said first air outlet.

14. An air mixing device as defined in claim 13 and further characterized by the recesses in said chamber rear portion being perforated.

15. An air mixing device as defined in claim 6 and further characterized by said ducts being arranged for substantially equal distribution throughout the volume of the casing.

16. An air mixing device as defined in claim 6 and further characterized by said ducts being individually axially disposed so that the openings therein open toward different portions of the chamber.

Claims

6. An air mixing device for use in air conditioning systems comprising means defining a chamber having an upper portion, a lower portion, side portions, and front and rear portions, there being a first air inlet in said upper portion, there being a first air outlet in said rear portion, a plurality of open-ended ducts each having a side wall between its ends provided within said chamber and extending from said front portion to said rear portion and opening at their respective ends therethrough, the forward ends of said ducts constituting a second air inlet, the rearward ends of said ducts constituting a second air outlet, and each of said ducts having an opening in its side wall between its ends and within said chamber whereby air may flow between said ducts and said chamber responsive to differential of pressures between the bodies of air entering said chamber through said first air inlet and through the forward ends of said ducts for effecting an equalization in pressure in the air being emitted through said first air outlet and said rearward ends of said ducts.

8. An air mixing device as defined in claim 7 and further characterized by said first air outlet in said rear portion comprising a multiplicity of apertures between thE rearward ends of said ducts.