US 3817160 A
An air distribution system comprising an elongated duct disposed along at least one vertical side of an opening between a cold first zone and a warmer second zone, air moving means at one end of the duct forming a longitudinal air flow pattern in the duct, air distribution means for laterally diverting the air flow toward the side of the duct adjacent to the opening, and air discharge means constructed and arranged for discharging the air flow horizontally across said opening at a uniformly varying angle with the lowest level of the air flow being at a predetermined angle toward the cold zone and the uppermost level of the air flow being at a predetermined angle toward the warmer zone.
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Description (OCR text may contain errors)
United States Patent [191 Searcy et al.
[111 3,817,160 June 18, 1974 AIR DOOR FOR COOLER OR THE LIKE  US. Cl 98/36, 98/40 C, 239/598  Int. Cl F24f 9/00  Field of Search 98/36, 40 C; 239/597, 598
 References Cited UNITED STATES PATENTS 6/1965 Weisz 98/36 3,218,952 11/1965 Gygax i 98/36 3,301,167 1/1967 Howard et a1 98/115 LH FOREIGN PATENTS OR APPLICATIONS 971,345 l/l959 Germany 98/36 1,363,426 11/1966 France 239/597 Primary ExaminerWilliam E. Wayner Attorney, Agent, or Firm-Richard G. Heywood  ABSTRACT An air distribution system comprising an elongated duct disposed along at least one vertical side of an opening between a cold first zone and a warmer second zone, air moving means at one end of the duct forming a longitudinal air flow pattern in the duct, air distribution means for laterally diverting the air flow toward the side of the duct adjacent to the opening, and air discharge means constructed and arranged for discharging the air flow horizontally across said opening at a uniformly varying angle with the lowest level of the air flow being at a predetermined angle toward the cold zone and the uppermost level of the air flow being at a predetermined angle toward the warmer 6 Claims, 7 Drawing Figures AIR DOOR FOR COOLER OR THE LIKE BACKGROUND OF THE INVENTION The invention relates generally to air distribution systems, and more particularly to improvements in air flow arrangements for doors or like openings between two zones of different temperature.
In recent years many advances have been made in the refrigeration art, especially in the commercial refrigeration field such as supermarkets. Based upon development work dating back about years, a high degree of success can now be achieved in designing sophisticated refrigerated equipment for displaying food products at temperatures ranging from 20F to about 50F utilizing air flow control and vertically disposed air curtain arrangements to isolate the open front of a refrigerated food display case from the warmer and more humid ambient zone. However, prior to the present invention the same degree of success has not been achieved in utilizing air curtains to separate adjacent cold and warm zones accessible through doorways or like vertical openings which may be subjected to heavy traffic patterns.
One of the major problems involving doorway openings communicating relatively cold and warm areas is that the heavier or dense, cold air will spill out at the bottom of the doorway and be replacedby an inward flow of the lighter, warmer air at the top of the doorway. This phenomenon is now generally recognized in the refrigeration art and is identified as the stack effect, which consists of a physical force of the cantilever type whereby the flow potential established as a result of the temperature difference is a constantly varying potential (linear) with the maximum cold outward flow force at the bottom being equal and opposite to the warm inward flow force at the top and a gradually decreasing effect in both directions to a neutral zone at the vertical center of the doorway opening.
In the past, many attempts have been made to utilize air curtains across open doorways to prevent the egress of cold air and ingress of warmer air, but conventionally such air curtains have been discharged downwardly from the top of the doorway and are variably directed outwardly against the warmer air zone at the top. It has been suggested that lateral or horizontal air curtains may be used, but previous attempts have treated the stack effect as a step function potential rather than a constantly varying potential (indicating that it has not been thoroughly understood), and the apparatus proposed heretofore has been complex, difficult to adjust and maintain and has not been effective.
SUMMARY AND OBJECTS OF THE INVENTION Briefly, the invention comprises an air distribution system having a longitudinal duct vertically disposed at one side of an opening between relatively cold and warm zones, means for evenly distributing air throughout the duct and in a horizontal direction toward the side of the opening, and air discharge means arranged throughout its length to discharge air across the opening at constantly varying angles from an outward angle toward the warm zone at the top to an inward angle toward the cold zone at the bottom.
The principal object of the present invention is to provide a simple, effective air distribution system that will obviate the stack effect in openings communicating relatively cold and warm zones.
Another object is to provide an air distribution system adapted to distribute and balance air flow at relatively low velocities and discharge such air flow evenly across a doorway in predetermined varying directions, and which will eliminate the need for an air return.
Another object is to provide an air distribution system that is adaptable for installation under different environmental conditions, and is effectively operable in such different installations.
These and other objects and advantages will become apparent hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS For purposes of illustration and disclosure, the invention is embodied in the parts and in the arrangements and combinations of parts hereinafter described and claimed. In the accompanying drawings which form a part of the specification and wherein like numerals refer to like parts wherever they occur:
FIG. 1 is a front elevational view of a cooler door or like opening having an air distribution system embodying the present invention,
FIG. 2 is a sectional view taken along line 2-2 of FIG. 1 showing, in end elevation, the air distribution system,
FIG. 3 is an enlarged perspective view of the air distribution system,
FIG. 4 is a horizontal cross-sectional view taken substantially along line 4-4 of FIG. 2,
FIG. 5 is a horizontal cross-sectional view taken substantially along line 5-5 of FIG. 2,
FIG. 6 is a horizontal cross-sectional view taken substantially along line 6-6 of FIG. 2, and
FIG. 7 is a vertical cross-sectional view taken substantially along line 7-7 of FIG. 2.
DESCRIPTION OF THE PREFERRE EMBODIMENT Referring now to the drawings wherein an air distribution system 10 embodying the present invention is illustrated for purposes of disclosure, the air distribution system 10 is shown in a preferred application as forming an air curtain AC across a doorway opening 11 in a vertical wall 12 between a refrigerated walk-in cooler, meat cutting room or the like 13 and a warmer, ambient food store area 14 of the like. However, it will be understood that this system may be readily adapted to other environmental applications such as isolating an air conditioned room from ambient.
The air system 10 comprises a longitudinal duct 16 extending vertically along one side of the doorway opening 11, the duct 16 including a wall member 17 attached to the cooler wall 12 and an outer opposed wall 18 defining there-between the width of the duct 16 and the lateral dimension of the air curtain to be formed by the system 10. The rear side of the duct 16 is closed by a side wall 19 and the opposed side wall is adjacent to the plane of the opening 11 and defines the air discharge means, shown generally at 20, to be described presently. The ductwork 16 is closed by a bottom wall 21 and a top wall 22.
According to the preferred form of the present invention, the air distribution system 10 is of the nonrecirculating type and utilizes ambient air. An air moving means 23 comprises a housing 24 for a squirrel cage blower 25 driven by a variable speed motor 26 to draw ambient air inwardly through a filtered intake port 27 and discharges an air flow downwardly through an air discharge conduit 28 secured to the top wall 22 of the duct. Thus, the initial air flow of the air distribution system is vertically downwardly into a plenum chamber 29 of the duct 16, as represented by the arrows I in FIG. 7.
The plenum chamber 29 comprises a longitudinal wedge-shaped or tapering portion of the duct 16 defined on the air discharge side 20 by a velocity air distribution panel 31, preferably formed of honeycomb material comprising separate, multiple, contiguous, elongated passages 32 having parallel axes. The panel 31 has upper and lower ends 33 and 34 engaged against the top and bottom walls 22 and 21 of the duct 16, and extends between the walls 17 and 18. It is important that the bottom margin 34 of the panel 31 is spaced from the closed side wall 19 of the duct 16 a short predetermined distance, such as /2 inch as indicated by numeral 34, so that the angularity of the honeycomb panel 31 is preset to provide proper air distribution throughout the length of the plenum 29 in duct 16 in order that each passage 32 will receive substantially equal amounts of the air flow (I). In practice, it also has been found that a panel 31 of honeycomb material having 3/16 inch cells and being /2 inch thick is effective to perform the added air distribution function of turning the initial air flow I into a substantially horizontal secondary air flow pattern S, as shown in FIG. 7.
A substantially vertical air balancing member 36 comprises a perforated metal panel having a lower edge 37 abutting the lower duct wall 21 and an upper edge 38 spaced below the top wall 22, but engaged against the honeycomb panel 31 adjacent to its upper edge 33 and spanning between the walls 17 and 18. The metal panel 36 (called moire) has perforations 39 and, with the honeycomb panel 31, defines an inverted wedge-shaped settling chamber 40 to compensate for any minor non-uniformity in air velocities and distribution occurring by reason of installation mishandling or honeycomb imperfections.
Referring particularly to FIGS. 36, the air discharge side 20 of the air distribution system 10 will now be described. The air discharge means 20 comprises another panel 41, preferably formed of honeycomb material having separate, multiple, contiguous, elongated, horizontally disposed passages 42, and it has been found that material having Vs inch cells and being 2 inches thick is effective for the air discharge function of this air distribution system 10. It should also be recognized that honeycomb material, while having sufficient rigidity to normally maintain its shape when subjected to normal air flow problems, also has a degree of flexibility that is important in carrying out the present invention.
The basic function of the air distribution system 10 being to obviate the stack effect, an important aspect of the invention is the discovery that the plasticity of the honeycomb material may be utilized to provide relative angularity of air flow discharge by twisting the discharge panel 41 throughout its vertically longitudinal dimension. In other words, the panel 41 is mounted in the duct 16 in a frame 43 maintaining a convolution of the panel to discharge the horizontal air curtain AC across the doorway 11 and provide a uniformly varying angularity of passages 42 in vertical disposition to each other. At the top, FIG. 4, the passages are at an out ward angle of from to 30 to act in opposition to the inward flow potential of the warmer air from ambient 14; and at the bottom, FIG. 6, the passages are at an inward angle of from 15 to 30 to act in opposition to the outward flow potential of the colder refrigerated zone 13. At the center, FIG. 5, the air discharge passages 42 are in the plane of the doorway opening 11, and it will be recognized that the angularity is constantly varying between these portions of the panel 41 and throughout its entire vertical length. It has been discovered that an angularity at the top and bottom of 20 from the plane of the opening 11 affords a satisfactory, efficient air curtain AC across the opening.
For purposes of better illustrating the convolution of the panel 41, the drawings are exaggerated and show the framing 43 to be formed angularly from the plane of the walls 17 and 18. However, in practice this arrangement may not be necessary. Furthermore, the flow potential of the air curain AC is represented in FIG. 2 by the arrows P as a linearly (phantom line L) counteracting force to the stack effect in order to better understand the phenomenon and the present invention.
In the operation of the air distribution system 10, the air moving means 23 draws ambient air into the intake port 27 and discharges the air flow pattern I downwardly at a predetermined relatively low velocity in the plenum chamber 29. The angularity of the panel 31 relative to the length of the duct 16 provides an essentially even air distribution throughout the height of the duct; but, rather than utilizing static regain" (in which the plenum is pressurized to force the flow of air into a lateral or tangential component) the angle of attack of the air flow 1 into the passages 32 in panel 31 is arranged or adjusted by the spacing 34 so the passages 32 receive substantially equal amounts of air and the velocity head is used to accomplish both the air distribution factor in the plenum 29 and the lateral air movement or turning factor through the passages 32 into the horizontal or secondary air flow pattern S.
As previously indicated, the moire air balancing member 36 evens out any discrepancies in the secondary air flow characteristics, and the horizontal air flow is then discharged through the air discharge panel 41 at different angles to compensate for the stack effect throughout the vertical dimension of the doorway 11.
The present air distribution system 10 may be utilized on doorways or like openings of different widths and is basically designed without requiring any air return or air curtain recirculation. However, it should be recognized that in exceedingly wide doorways opposed systems 10 may be employed or a push-pull air discharge and return arrangement may be more efficient. The shape of the velocity profile provided by the blower 23 is constant; but at different cold-warm temperature extremes or varying temperatures, the stack effect may be more or less pronounced so that variation in the speed of the blower 23 may be required to compensate for the differences in flow potential.
From the foregoing it will be readily apparent that a highly efficient air distribution system has been provided, meeting the objects and advantages heretofore set out. This invention is intended to encompass all changes and modifications readily apparent to those skilled in the arts of fluid dynamics and refrigeration.
What is claimed is:
1. An air distribution system for forming an air curtain across an opening between relatively cold and warm zones, comprising longitudinal duct means vertically disposed along one side of the opening, means for distributing air substantially evenly throughout said duct including air moving means positioned at one end of said longitudinal duct means and a velocity air distribution member angularly positioned in said duct means and defining therewith a tapering plenum chamber, said air moving means discharging an air flow vertically in said plenum chamber from the wider end to the narrower end thereof and said velocity air distribution member diverting said vertical air flow into a horizontal direction toward said opening, and air discharge means arranged throughout the vertical length of said opening to discharge an air curtain horizontally across the opening and at substantially constantly varying angles relative to the plane of said opening.
2. The air distribution system according to claim 1, in which said velocity air distribution member comprises a panel formed of separate multiple, contiguous, elongated, substantially horizontally disposed passages having inlet ends positioned in said plenum chamber.
3. The air distribution system according to claim 2, in which said air distribution member is angularly positioned in said duct means in opposed spaced relation to a closed wall of said duct means to define a wedgeshaped plenum chamber, the spaced relation between said air distribution member and closed wall at the end of the duct means remote from said air moving means being predetermined to establish the angle of attack of said vertical air flow relative to the inlet ends of said passages of said panel.
4. The air distribution system according to claim 1, including a perforated air balancing member extending vertically in said duct means between said velocity distribution member for diverting said air flow into said horizontal direction and said air discharge means.
5. An air distribution system comprising an elongated duct disposed along at least one vertical side of an opening between a cold first zone and warmer second zone, air moving means at one end of said duct and forming an air flow longitudinally in the duct, air distribution means for laterally diverting said air flow toward the side of the duct adjacent to the opening, air balancing means for evening the lateral air flow throughout the length of said duct, and air discharge means at said one side of said duct and being constructed and arranged for discharging the air flow horizontally across said opening at a uniformly varying angle with the low est level of air flow being at a predetermined angle toward said cold zone and the uppermost level of air flow being at a predetermined angle toward the warmer zone.
6. An air distribution system for forming an air curtain across an opening between relatively cold and warm zones, comprising longitudinal duct means disposed along at least one side of the opening, means for distributing air substantially evenly throughout said duct including a velocity air distribution member angularly positioned in said duct means and defining therewith a tapering plenum chamber having a large end and a relatively narrow end and air moving means in communication with the large end of said plenum chamber, said air moving means discharging an air flow in the longitudinal direction of said duct means throughout said plenum chamber from the large end to the narrow end thereof and said velocity air distribution member diverting said air flow in a direction normal to said longitudinal duct and toward said opening, air discharge means arranged throughout its length to discharge an air curtain across the opening, and air balancing means extending longitudinally in said duct means between said velocity air distribution member and said air discharge means for evening the air flow to said air discharge means throughout the length of said duct means.