US3182466A

US3182466A - Conditioned storage cabinet

Info

Publication number: US3182466A
Application number: US181525A
Authority: US
Inventors: Beckwith Sterling
Original assignee: Dual Jet Refrigeration Co
Current assignee: Dual Jet Refrigeration Co
Priority date: 1962-03-22
Filing date: 1962-03-22
Publication date: 1965-05-11
Anticipated expiration: 1982-05-11

Description

May 11, 1965 s. BEcKwm-l CONDITIONED STORAGE CABINET May l1, 1965 s. BEcKwlTH 3,182,466

CONDITIONED STORAGE CABINET Filed March 22, 1962 2 Sheets-Sheet 2 United States Patent til-ice 3,l82,d6 Patented May ll, 1955 3,1S2,466 CNDITHNED STORAGE Cellhijll- Steriing Beckwith, Libertyville Township, lil., assigner, by mesne assignments, to Dual .l et Refrigeration Company,

a corporation of illinois Filed Mar. 22, 1%2, Ser. No. 181,525 2 Claims. (Cl. 62-256) This invention relates to the conditioning of an enclosed space having one side which is open to the atmosphere for access to the interior of the conditioned space for observation of the contents therein or for displacement of material into and out of said conditioned space.

As used herein, the term conditioning or conditioned space is intended to refer to the maintenance of the space under variously desired conditions, such for example as under oxidizing conditions, as by the use of oxidizing gases (oxygen); reducing conditions, as by use of reducing gases (hydrogen); inert conditions, as by use of an inert gas (argon); refrigerated conditions, as by the use of refrigerated air; heating conditions, as by the use of heated air; moist conditions, as by the use of air at high humidity; and desiccating conditions, as by the use of dry air, etc. The invention will hereinafter be described with reference to the use of the enclosed space as a part of a refrigerated display cabinet for frozen or refrigerated foods whereby the storage space is adapted to be maintained in a refrigerated state having a temperature at or below freezing. The same concepts for maintenance of the space in a refrigerated state will apply in the maintenance of the space at others of the described conditions, as will become apparent from the following.

In the co-pending application of Hagen et al., Serial No. 54,077, filed September 6, 1960, now Patent No. 3,134,243 granted May 26, 1964, and entitled Refrigerated Display Case, and in the issued Simons Patent No. 2,862,369, description is made of a refrigerated display cabinet having a storage space with an open side. Loss of heat from the storage space through the open side is substantialy obviated by passage of a curtain of air continuously across the space from one edge to an opposite edge thereby to blanket the entire opening by the formed curtain.

The air curtain is adapted to be formed of adjacent panels of air with the inner panel corresponding to the condition desired to be maintained within the enclosed space and with one or more outer panels corresponding more closely to the ambient atmosphere. The inner panel is referred to as the conditioned panel while the outer panel or panels are referred to as the guard panels. For most ei'licient practice, it is desirable to recirculate at least the inner panel of conditioned air and the guard panels thereby to conserve on the investment in conditioning required to maintain the space in the desired refrigerated state, or heated state, dry, wet, oxidizing or reducing state.

For example, in the Simons patent use is made of an air curtain formed of but two panels comprising an inner cold air panel which is refrigerated and continuously recirculated and an outer ambient air panel which is cut off from the cold air panel for return to the atmosphere. On the other hand, in the aforementioned co-pending application of Hagen et al., illustration is made of an arrangement which makes use of an inner cold air panel and an outer panel both of which are recirculated through separate systems in the cabinet whereby the outer panel acquires a temperature intermediate the cold air panel and the ambient temperature to function as a guard panel which minimizes heat loss while at the same time enhancing laminar flow, as will hereinafter be pointed out. Also disclosed in the aforementioned application of Hagen et al. is an arrangement wherein the curtain is formed of three recirculating panels in side-by-side relationship further to increase the efficiency of operation from the standpoint of flow characteristics of the air curtain and heat loss from the conditioned space.

In the aforementioned constructions, description is made of an arrangement wherein the nozzles extend across the bottom edge of the opening to direct the air panels upwardly across the opening towards the inlets extending across the top side of the opening. Description is also made of an arrangement ywith the nozzles located across the upper edge of the opening for causing the air panels to flow downwardly across the opening to inlets across the bottom side of the opening. It will be understood that the air nozzles can also be located across one of the lateral edges of the opening for directing the air panels across the opening towards the inlets in the opposite edge. Because of the more desirable effect of gravity on the higher density cold air, it is preferred to flow the air curtain downwardly from nozzles across the top to inlets across the bottom and the invention will hereinafter be described with reference thereto, but it will be understood that the concepts hereinafter described will also be applicable to other directional flow.

To minimize the investment in power required to achieve the desired refrigeration in the inner air panel, it is desirable to minimize the amount of intermixing between the adjacent panels making up the air curtain as the panels travel together across the open space. For this purpose, it is desirable to maximize laminar flow between the air panels making up the curtain which is continuously moved across the fopen space. Various factors including nozzle construction, air speed, directional ilow and the like have been found to have material inlluence on laminar ow.

lt is an object of this invention further to enhance laminar flow of the air panels across the open space by construction of the cabinet to take into consideration another factor found to have considerable influence on the iiow characteristics of the air panels and on the amount of intermixing that takes place between the panels.

More specifically, it is an object of this invention to produce a cabinet of the type described embodying means within the space to be conditioned which assists in maintaining the directional flow of the air panels and minimizes cross air currents which might intercept the air curtain and cause turbulence with corresponding excessive intermixing of air between adjacent panels.

These and other objects and advantages of this invention will hereinafter appear and for purposes of illustration, but not of limitation, embodiments of the invention are shown in the accompanying drawings in which- FIG. 1 is a schematic sectional elevational view of the conditioning cabinet embodying the features of this invention;

FIG. 2 is a schematic sectional elevational view similar to that of FIG. 1 showing a modication in the cabinet construction;

FG. 3 is a schematic elevational view showing the effect of air flow in a cabinet embodying the features of this invention; and

FG. 4 is a schematic view similar to that of FIG. 3 illustrating a further concept of this invention.

The cold storage or refrigerated display case shown in the drawings is generally designated by the numeral lil. The case is constructed with an outer housing wall including a top wall 12, a back wall 14, a bottom wall i6, vertical side walls 1S and a front wall 20, the latter of which is provided with an access opening 22. The housing rests upon a suitable base 24.

Spaced inwardly from the housing walls in substantially parallel relationship is an inner wall including top, back, bottom, side and

front walls

26, 28, Si), 31 and 32 respectively which dene the interior of a storage space 3d. The

about the storage space from

outlets

54 and 56 at one edgeY of the opening 22 to inlets 62 and 64 at the opposite edge of the opening 22.

Located within the inner passage 40 are refrigeration Y coils 42 through which a suitable refrigerant is circulated for indirect heat exchange to cool air passing through the passage 46 into contact with the coils. Although the refrigeration means is illustrated as being located centrally within the passage 4t?, the refrigeration or evaporator coils 42. can be located in other portions of the passage, but preferably in the upstream portion thereof. Located in the upstream side of the passage and between the refrigeration coils and the inlet 62 `is an air circulating means, such as a fan or blower 44 for causing the stream of air to flow through the passage 40 from the inlet 62 to the outlet 54 and from the outlet 54 to the inlet 62 across the open space 22 to form the inner cold air panel 58 of an air curtain.

Similarly :located within the outer passage 38 is another air circulating means, such as a blower 46 for causing air to flow from the inlet 64 through the channel 38 to the outlet 56 and from the outlet 56 to the inlet 64 across the open space 22 to form an outer panel 60 of the air curtain flowing in substantially parallel relation with the inner cold air panel.

The outlet 54 of the inner passage 4t) is in the form of a nozzle 55, such as a honeycomb section, which extends continuously across the top side of the access opening 22 in the front wall of the refrigerated display case. Similarly the outlet 56 for the outer passage 38 is in `the form of a nozzle 57, of a vaned or honeycomb section, which also extends substantially continuously across the top side of the access opening along side the nozzle 55 and in substantially parallel relationship therewith.

The streams of air issuing from the

outlets

54 and 56 form continuous inner and outer air panels 58 and 6i) respectively which extend across the access opening 22 from the outlets S4 and 56 to the inlets 62 and 6d. The nozzle 55 is positioned to` direct the inner panel 58 of cold or conditioned air to the inlet 52 in communication with the j and as.

cold air return passage 4t! while the nozzle Seis positioned 6d which is intermediate the temperatures of the cold air panel and the temperatures of the ambient air. Thus the guard panel at intermediate temperature is interposed between the inner panel of cold air and the atmospheric air thereby to guard the cold air from the heat of the atmosphere and whereby air entrained from the guard panel into the cold air panel is at considerably lower temperature than the air from the atmosphere which otherwise would be the component admixed. To minimize heat loss into the cold air recireulated through panel dit, it is desirable, though not essential, that the partitioning wall 36 and the outer wall lebe provided with suitable insulation, designated by the numeral 74.

The velocity sufficient to maintain the air panels for minimum entrainment has been found to be within the range of to 1,500 feet per minute with about 1GO to 400 feet per minute being preferred for most refrigerated eases of conventional dimension.

By way of still further modification, instead of making use of a single guard jet, additional guard jets may be provided whereby the air panels, extending across the access opening 22, will correspond to the number of such jets. In` the modification illustrated in FIG. 2, one additional guard jet lo@ is employedrto provide three parallel streams of-air Sii, 6@ and 192 extending across the access opening 22. lt will be understood that more than one additional jet may be provided. f

Such additional jets will operate further to reduce the temperature differential between the jets. Thus, the guard jet adjacent the inner panel of cold air will be at a temperature still closer to the temperature of the cold air stream such that entrainment of air from one panel yto the other will have minimum effect on the temperature thereof. Y

An important concept of this invention resides in the subdivision of the conditioned space with one or more solid barriers, such as shelves 82 which span the enclosed space continuously from the back wall to the air panel to extend crosswise of the air panel and thus subdivides the space into two or more completely separated sections 84 It is desirable for the separating shelf to extend to the inner edge of the aircurtain and preferablyfor a distance to project partially into the direct line of travel of the air curtainfrom the outlet nozzle 54 to the inlet 62. When the outer edge of the shelf Vor shelves-terminates some distance short of the straighty line function between outlet and inlet, there is a tendency for the air curtain to bend excessively into the conditioned space above the shelf and to bend even more substantiallybeyond the shelf, whereby substantial amounts of the conditioned air enter the conditioned space for subsequent re-entry into the air curtain in the vicinity of the inlets again to induce turbulence and excessive intermixing of the air between the panels.

On the other hand, when the shelves .82 extend outwardly into the line of travel between the outlets and the inlets, but not beyond the line of travel, the barrier presented by the shelf or shelves prevents excessive excursions of the air curtain-into the conditioned space. instead, the air curtain becomes straightened out for substantially linear ow with but slight deviation from the outlet to the inlet, as illustrated in FIG. 3, thereby to minimize interferences with the desired laminar flow. Such subdivision of the conditioned space has been found'toi be effective to reduce intermixing between the panels Yto an amount less than 20 percent from an'otherwise value of 30 percent or more in the absence of the separating shelf or when the shelf or shelves terminate short of the line of travel between the outlets` and inlets. The improvement is more noticeable in refrigeration where the inner panel comprises `the cold air panel and wherein the air curtain travels downwardlyl from outlets across the top edge of the space to inlets across the bottom edge and with the inlets offset outwardly from the outlets whereby gravity is more influential in bending thelair curtain.

Another important concept of this invention resides in the construction of the shelf or shelves with outer lips 99 which depend downwardly from the outer edge of the shelf preferably at an incline somewhat parallel to the angle of a line drawn between the outlets and inlets. The lips 9G serve to turn the stream formed by the small amount of air entering the lower portion of the conditioned space so that, as the air stream circulates about the space from the `back side forwardly across the top, it will be bent downwardly by the lip for smooth re-entry into the air curtain'with substantially parallel ow so that reentry will be achieved without interferences that might otherwise cause turbulence.

The separating wall or shelves can extend substantially horizontally across the conditioned space, as illustrated in FIGS. 3 and 4, or they can extend angularly downwardly from the back side, especially when the conditioned space comprises a refrigeratedspace for the storage and display of packaged or the like refrigerated foods. By theuse of such downwardly inclined shelves, the packaged foods or other products stored on the shelves will become displaced automatically gravitationally to bring the products on the shelves to the outer edge for better display and easier accessibility.

The lip 90 can extend upwardly from the forward edge of the shelf as a stop for the packaged goods. It is desirable to minimize the distance that the lip extends downwardly from the shelf to avoid excessive obstruction of the open side of the conditioned space. It is sucient if the lip projects downwardly for a distance suicient to iniluence the directional flow of the air current traveling forwardly adjacent the under side of the shelf, as illustrated in FIG. 4, usually an amount less than 1 to 2 inches.

By way of illustration of the operation of the cabinet as a refrigeration means for the storage of frozen foods, refrigerant is circulated to the evaporator coils for cooling the coils to a temperature to reduce the air circulating through the passage 40 to about 15 F. This will be sutlicient to maintain the space within the cabinet at a temperature whereby the packaged foods mounted upon the shelves will be retained below F. When the cold air stream is at a temperature of about F., it will be found that the temperature of the guard stream adjacent thereto will be at a temperature slightly above freezing during the travel of the air panels as a curtain across the open space. It will be understood that when use is made of the space for heating or for oxidizing or for reducing, etc., the desired hot air, oxidizing atmosphere, reducing atmosphere or the like will be substituted for the refrigerated air forming the inner cold air panel.

It will be apparent from the foregoing that I have provided a construction within a conditioned space of the type described having influence to improve the laminar flow characteristics of the air panel projected across the open space whereby less intermixing is experienced and more eicient utilization is made of the conditioning material.

It will be apparent that other changes may be made in the details of construction, arrangement and operation without departing from the spirit of the invention, especially as delined in the following claims.

I claim:

1. In a cabinet having an enclosed space with an access opening on one wall communicating the otherwise enclosed space with the ambient atmosphere in an air ilow system which consists of, outlet nozzles extending continuously only across one edge of the opening in side by side parallel relation and corresponding inlet means extending only across the opposite edge of the opening, means for projecting a continuous curtain of air across the opening from the outlet nozzles to the inlets, said curtain defining an interior face moving directly in contact with the relatively still air Within the enclosed space, with all the air entering the inlets being recirculated to the outlets without intermediate bleeding off of air into the enclosed space and a solid barrier exending continuously across an intermediate portion of the enclosed space from the far end portion thereof to a line substantially flush with a line drawn from the outlet nozzles to the inlets across the accessl opening, said line extending beyond the plane of movement of said interior face whereby said barrier terminates at a point partially within the line of travel of said curtain, said barrier being positioned to extend crosswise of the direction of flow of the air curtain from the outlet nozzles to the inlets and which includes a lip on the edge of the barrier adjacent the end curtain and in which the lip extends upwardly and downwardly beyond the barrier from the edge of the barrier to redirect air in the space beyond the barrier into the end curtain.

2. A cabinet as claimed in claim 1 in which the air curtain is formed of at least two air panels comprising an inner panel conditioned to correspond to the conditions desired to be maintained Within the enclosed space and outer panels intermediate the conditioning panel and the ambient atmosphere.

References Cited lay the Examiner UNITED STATES PATENTS 2,421,314 5 47 Brinkoeter 62-25 6 2,822,672 2/5 8 Dickson 62-25 6 3,063,256 11/62 Lamb 62-256 FOREIGN PATENTS 865,148 4/61 Great Britain.

ROBERT A. OLEARY, Prmyary Examiner.

WILLIAM I. WYE, Examiner.

Claims

1. IN A CABINET HAVING AN ENCLOSED SPACE WITH AN ACCESS OPENING ON ONE WALL COMMUNICATING THE OTHERWISE ENCLOSED SPACE WITH THE AMBIENT ATMOSPHERE IN AN AIR FLOW SYSTEM WHICH CONSISTS OF, OUTLET NOZZLES EXTENDING CONTINUOUSLY ONLY ACROSS ONE EDGE OF THE OPENING IN SIDE BY SIDE PARALLEL RELATION AND CORRESPONDING INLET MEANS EXTENDING ONLY ACROSS THE OPPOSITE EDGE OF THE OPENING, MEANS FOR PROJECTING A CONTINUOUS CURTAIN OF AIR ACROSS THE OPENING FROM AND OUTLET NOZZLES OF THE INLETS, SAID CURTAIN DEFINING AN INTERIOR FACE MOVING DIRECTLY IN CONTACT WITH THE RELATIVELY STIL AIR WITHIN THE ENCLOSED SPACED, WITH ALL THE AIR ENTERING THE INLETS BEING RECIRCULATED TO THE OUTLETS WITHOUT INTERMEDIATE BLEEDING OFF OF AIR INTO THE ENCLOSED SPACE AND A SOLID BARRIER EXENDING CONTINUOUSLY ACROSS AN INTERMEDIATE PORTION OF THE ENCLOSED SPACE FROM THE FAR END PORTION THEREOF TO A LINE SUBSTASNITALLY FLUSH WITH A LINE DRAWN FTOM THE OUTLET NOZZLES TO THE INLETS ACROSS THE ACCESS OPENING, SAID LINE EXTENDING BEYOND THE PLANE OF MOVEMENT OF SAID INTERIOR FACE WHEREBY SAID