US3218822A

US3218822A - Frozen food display case

Info

Publication number: US3218822A
Application number: US403618A
Authority: US
Inventors: George K Bently; Glenn W Mathis
Original assignee: MCCRAY REFRIGERATOR Co IN
Current assignee: MCCRAY REFRIGERATOR Co IN; MCCRAY REFRIGERATOR COMPANY Inc
Priority date: 1964-10-13
Filing date: 1964-10-13
Publication date: 1965-11-23
Anticipated expiration: 1982-11-23

Description

Nov. 23, 1965 G. K. BENTLY ETAL FROZEN FOOD DISPLAY CASE 2 Sheets-Sheet 1 Filed Oct. 13, 1964 INVENTORS: E3025 K BENTLY BY GLENN W. MAQZHIS QMQW ATTYS- N 1965 G. K. BENTLY ETAL FROZEN FOOD DISPLAY CASE 2 Sheets-Sheet 2 Filed Oct. 13, 1964 INVENTORS 5502252 K. BENTLY.

. BY ELENNHZMATHIE.

United States Patent Ofiice 3,218,822 Patented Nov. 23, 1965 3,218,822 FROZEN FOOD DISPLAY CASE George K. Bently and Glenn W. Mathis, Kendallville, Ind., assignors to McCray Refrigerator Company, Inc, Kendallville, Ind., a corporation of Indiana Filed Oct. 13, 1964, Ser. No. 403,618 9 Claims. (Cl. 62 256) This invention relates to a display case for frozen foods or the like and is particularly directed to means including a localized heat source for enhancing the comfort of customers using such cases and at the same time improving the flow of refrigerated air in the case itself.

Recently developed frozen food cases or display units give the appearance to the customer of being little more than a series of open shelves on which the goods are displayed. This arrangement places the frozen goods closer to the eye level of the customer and renders it easy for him to reach in and pick up packages of frozen foods. The frozen food case actually comprises a series of superposed shelves, each of which is subject to a carefully controlled flow of very cold air, with the front of the case separated from the facing atmosphere by a curtain of cold air, usually flowing in a downward direction. The velocity and volume of the shelf cooling air and the refrigerated air curtain are such that the front edge of each of the display shelves can be maintained at or near F. while the ambient air three or four inches away may be at 70 F. Near the bottom of the open front of the display case, the air of the curtain is joined by the shelf cooling air and the combination is drawn into a return air duct to be re-cooled, dehumidified and recirculated. In theory there is little or no spillage of cold air at this return point, because of the lower pressure existing at the duct inlet, but in actual practice some of the cold air spills down the front of the base of the case, creating an uncomfortable area in which the customer must stand while making a selection of the frozen foods displayed in the case. This has a tendency to drive the customer away from the refrigerated case and tends to defeat the main purpose of the upright case, of increasing sales. In addition, body heat is radiated to the relatively cold base to further increase discomfort.

In a co-pending application of Bently and Mathis, Serial No. 249,167, now Patent No. 3,186,185 we have disclosed a means to reduce the spillage of cold air into the aisle in front of the case by introducing a counter-flowing stream of heated air emerging near the return air duct. This expedient has improved customer comfort and has also improved the air flow characteristics of the refrigerating system by confining the cold air curtain inwardly of the discharge plane of the heated air.

We have now discovered that further improvement in customer comfort, and further improvement in air flow characteristics, can be made by introducing a radiant heating element near the base of the case. The heating element extends along the front of the case parallel to the floor at somewhat below knee height and radiates heat into the aisle to increase ambient temperature adjacent the base. The heating element also is associated with a duct system to set up a convective air flow that tends to warm the entire front of the case so that heat will not be lost by radiation from the customers body to the case itself, which loss would give rise to a feeling of discomfort.

The heating element and duct system also utilize the warm convection current to assist in directing the reentry of the cold air into the return duct of the refrigerating system and eliminate formation of frost at this point. Further, the heat of this convection current is used to raise the temperature of those parts of the case likely to be touched by the customer.

The invention further utilizes the radiant energy from the heater to reduce the accumulation of frost at a critical point in the air return duct. Any radiant heating device that utilizes a reflector necessarily heats the reflector. By conducting the heat from the reflector through the adjacent Wall of the case, and by properly positioning the heater itself, the heat loss to the reflector performs the function of reducing accumulation of frost on an area of the interior wall of the return duct where frost formerly tended to form. This is achieved by raising the temperature of the area, by the conducted heat, to a point above the dewpoint of the air stream.

Further objects and advantages of the invention will become apparent from the following description of a preferred embodiment thereof, reference being made to the accompanying drawings, in which:

FIG. 1 is an overall view in perspective of a refrigerated display case or unit embodying the invention;

FIG. 2 isa somewhat schematic vertical cross-sectional view taken along the line 22 of FIG. 1; and

FIG. 3 is an enlarged, fragmentary vertical cross-sectional view of heating means embodied in the upright refrigerated display case of FIGS. 1 and 2.

Referring to the drawings, and more particularly to FIG. 1, a refrigerated display case 10 embodying the invention includes a plurality of refrigerated display sections 12 with a continuous, longitudinally-extending top 14 and a continuous, longitudinally-extending base 16. The top and base give the case the appearance of being a single, integrated unit in spite of the fact that it is made up of a number of the modulus or sections 12. The sections 12 have common duct work and cooling coils, and a common, remotely-located compressor and condenser.

As shown in FIG. 2, the sections 12 include a plurality of shelves 18, some of which are supported above plenum chambers 20 attached to rear wall portions of the sections 12. A main air dehydrating and cooling coil assembly 22 is located at the lower rear of the section 12 and is supplied with refrigerant from a remote compressor unit which can supply several of the coil assemblies. The coil assembly 22 is designed not only to cool air passing therethrough, but also to bring the air temperature below the dewpoint to extract as much moisture as possible. An additional coil assembly 23 is located at the bottom of the section 12 and provides preliminary cooling of the air. Suitable means can be used to defrost the coils when necessary and suitable drain passages can be provided to collect and remove water from the coil assemblies.

A fan 24 is located in a lower chamber 26 containing the coil 23 and draws air through a return duct or flue 28 from an air inlet 30 and directs it toward the coil assemblies. The air is blown through the coil 22 and a supply duct or passage 32 to outlets 34 which direct the cold air to the chambers 20 and then over the frozen goods on the shelves 18. A cold air curtain supply duct 36 directs air to a cold air curtain outlet 38. The cold air from the outlet 38 moves uniformly downwardly past the shelves 18 to the lower inlet 30 from which it is recirculated by the fan 24 through the coil assembly 22. The cold air curtain thereby formed constitutes an important factor in confiining the cold air within the section 12 and the unit 10, and substantially increases the efliciency of the unit in this manner, causing a significant decrease in operating costs.

Normally, a certain portion of the cold air just above the inlet 30 tends to spill out of the unit 10 and over the base 16. This cold air is wasted and reduces the efl'iciency of the unit as well as causing an uncomfortable area for customers standing in front of the unit. As discussed in the aforementioned copending patent application, a

counter-flowing current of heated air can be provided immediately outside the cold air curtain to reduce this spillage, but we have found that there is still some discomfort to customers, which is due in part to the cold air and in part to the radiant heat loss from the customers body to the base of the case or unit. We have also found that there has been a tendency for frost to form adjacent the inlet 30 and to form in a lower front portion or area 40 of the return duct 28.

To overcome the above-discussed disadvantages, the present invention provides a heating system at the front of the base 16. The system includes a radiant heating element 42 held by suitable supports 44 at or near the focal point of a reflector 46, a protective grid 48 being mounted in front of the element and reflector. The heating element or rod 42 extends substantially the length of the entire case and is connected at its ends to a suitable power supply (not shown). If desired, several of the heating elements 42 can be connected together electrically, with suitable power connections then being provided at each end of the case 10. The reflector 46 is disposed in a base wall 50 of the base 16 and extends close to the rear surface of the wall 50 near the duct area 40 where frost has heretofore had a tendency to form. Much of the heat loss from the element 42 to the reflector 46 is utilized by being conducted through the wall 50 to the area 40 to raise the temperature sufiiciently to prevent frost formation at this point in the system.

The heating element 42 and the reflector 46 effectively radiate heat outwardly into the aisle in front of the base 16 to warm the legs of the customer standing there, as well as the adjacent floor thereby overcoming the chilling effect of any cold air spilling over the front of the base. The radiated heat also helps to overcome any loss of heat radiated from the body of the customer to the display case.

An air flow duct system is provided in cooperation with the heater element 42 and its associated components to achieve additional purposes of the heating system and to increase its usefulness. Below the heating element 42 and its components are

air inlet chambers

52 and 54 having

inlets

56 and 58 located near the floor for receiving air and passing it through an inlet 60 to the rear of a lower rail 62 and to a supply passage 64 formed by a lower outer wall 66 of the base. The air drawn through the

inlets

56 and 58 passes through a lower outlet 68 and past the heating element 42. This heats the air by radiation and conduction and provides a chimney effect causing the air to rise by drawing additional air upwardly through the passage 64. The chimney effect of the heated air not only draws in air from the lower outlet 68 but it also can draw some air through the protective grid 48. The air then flows through a vertical passage 70 formed between the base wall 50 and an outer upper wall 72 of the base. Part of this air passes into a front trim rail 74 and all of it flows through a passage 76 formed between the upper end of the wall 50 and a reach-in rail 78 extending along the top thereof. Finally, the warm air reaches an outlet 80 from which it is directed downwardly toward the in let 30. Most of this air will then be passed through the circulating system with the cold air, although some may tend to spill over the front of the case with any spilled cold air, thereby tempering the cold air and reducing its chilling effect.

The air duct work enables the front wall 72 of the base to be warmed and thereby reduces or eliminates any radiation from the customers body to the base 16. This air further warms the trim rail 74 as part of the warm air passes into and out of it while the reach-in rail 78 also is warmed as the air sweeps by it and curves downwardly. Finally, the still-warm air emitted from the upper outlet 80 tends to temper the air at the inlet 30 and reduces the formation of frost on the inner surface of the reach-in rail 78 which otherwise tends to occur. The velocity of the downwardly directed air from the display section helps pull into the inlet 30 the warm air from the outlet 80, maintaining a steady circulation of the warmed air. Even the ambient air passing into the

lower inlets

56 and 58 prevent the lower rail 62 and the lower wall 66 from being cooled nearly as much as otherwise.

Various modifications of the above described embodiment of the invention will be apparent to those skilled in the art, and it is to be understood that such modifications can be made without departing from the scope of the invention, if they are within the spirit and scope of the appended claims.

We claim:

1. In a refrigerated display case having a downwardly flowing cold air curtain separating and protecting shelfcarried refrigerated merchandise from the display room, said case including a base having a front wall and a return air duct terminating in an inlet adjacent the top of said front wall and subject to the loss of cold air to the room area in front of said base, the improvement comprising heating means mounted in said base to direct radiant heat energy outwardly into the display room area normally receiving the lost cold air, and means to direct an upward convection current of air heated by said heating means across the front of said base to the region of said return air inlet.

2.'The improvement defined in claim 1 in which the terminus of said current-directing means is adjacent said return air duct inlet and the final direction of flow of said convection current is in the direction of the air moving into said return air duct.

3. The improvement defined in claim 1 in which said convection air current is directed toward said duct inlet to heat the same to a temperature above the dewpoint of air drawn into said return air duct and thereby prevent frost deposition thereon.

4. An upright refrigerated display case comprising a plurality of vertically-spaced shelves, means forming a vertically-disposed duct behind said shelves, means forming a cold air outlet between each adjacent pair of shelves, means forming an additional outlet above the front edges of said shelves to direct a curtain of cold air downwardly in front of said shelves, means forming a return air inlet near the front edge of the lower shelf, a return air duct connecting said inlet with said vertically-disposed duct, fan means and cooling means in said return air duct to direct air from said inlet toward said vertically-disposed duct and to cool the air, generally upright duct means adjacent said inlet, and a radiant heater including a heating element and a reflector positioned to transfer heat from said heating element to air in said upright duct means to establish an upwardly moving current of warm air, and

said heating element and said reflector also directing.

radiant heat outwardly away from said display case toward space adjacent a lower portion thereof.

5. An upright refrigerated display case comprising a plurality of vertically-spaced shelves, means forming a vertically-disposed duct behind said shelves, means form ing a cold air outlet between each adjacent pair of shelves, means forming anadditional outlet above the front edges of said shelves to direct a curtain of cold air downwardly in front of said shelves, means forming a return air inlet near the front edge of the lower shelf, a return air duct connecting said inlet with said vertically-disposed duct, fan means and cooling means in said return air duct to direct air from said inlet toward said vertically-disposed duct and to cool the air, generally vertical duct means at the front of said case, and heating means associated with said vertical duct means to establish an upwardly moving current of warm air through said duct means to aid in warming thefront of said case and to radiate heat outwardly from said display case toward space in front of a lower por-- tion thereof.

6. An upright, refrigerated display case comprising a. plurality of vertically-spaced shelves, means establishing a downwardly moving curtain of cold air in front of all of said shelves, generally upright duct means positioned outside the cold air means, and a radiant heater including a heating element and a reflector positioned to transfer heat to air in said duct means to establish an upwardly moving current of warm air, and said heating element and said reflector also radiating heat outwardly away from said display case toward space adjacent a lower portion of the display case.

7. An upright, refrigerated display case comprising a base, a plurality of vertically-spaced shelves, means establishing a downwardly moving curtain of cold air in front of all of said shelves, generally upright duct means positioned at the front of said base outside the cold air means, and a radiant heater in said duct means effective to transfer heat to air within said duct means to establish an upwardly moving current of warm air to warm the front of said base, and said heater being effective to radiate heat outwardly, away from said case, toward space in front of said base of said display case.

8. An upright, refrigerated display case comprising a plurality of vertically-spaced shelves, means establishing a downwardly moving curtain of cold air in front of all of said shelves, a return air duct for recirculating the cold air, said duct having an inlet below the front of said shelves, generally vertical duct means positioned outside and below the cold air means, and heating means associated with said vertical duct means to establish an upwardly moving current of warm air through said duct means and to radiate heat outwardly from the display case toward space in front of a lower portion of the display case, said vertical duct means terminating in an end portion directing the warm air current downwardly toward said return air inlet and in the direction of flow of air entering said return air inlet.

9. In a refrigerator display case having a downwardly flowing cold air curtain separating and protecting shelfcarried refrigerated merchandise from the display room, said case including a base having a front wall and a return air duct terminating in an inlet adjacent the top of said front wall and subject to the loss of cold air to the room area in front of said base, the improvement comprising heating means mounted in said base to direct the radiant heat energy outwardly into the area of the display room normally receiving the lost cold air, said heating means being positioned relative to the return air duct to conduct heat to a portion of the interior wall of said return air duct to prevent the formation of frost on said interior wall portion.

References Cited by the Examiner UNITED STATES PATENTS 2,542,136 2/1951 Hanson 62248 2,706,387 4/ 1955 Swanson 62248 2,731,242 1/1956 Borg 16S133 2,836,039 5/ 1958 Weber 62256 3,025,681 3/1962 Booth 62248 3,125,864 3/1964 Ural 62256 WILLIAM J. WYE, Primary Examiner.