CA1068921A

CA1068921A - Diversion defrost display cabinet

Info

Publication number: CA1068921A
Application number: CA302,788A
Authority: CA
Inventors: Robert E. Vogel
Original assignee: Kysor Industrial Corp
Current assignee: Kysor Industrial Corp
Priority date: 1977-09-28
Filing date: 1978-05-08
Publication date: 1980-01-01
Also published as: FR2404415B1; AU519195B2; AU3622878A; DE2840483A1; JPS5454367A; FR2404415A1

Abstract

DIVERSION DEFROST DISPLAY CABINET
ABSTRACT OF THE DISCLOSURE
An energy conserving refrigerated display case having a control circuit that diverts electrical energy from the antisweat heaters operable during the refrigeration mode of the display, to an evaporator defrost heater during the defrost mode of the display. -1-

Description

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Refrigerated display cases are widely employed for effectively merchandising food products while maintaining such in prime condition. Yet, because of the significant energy usage requirements of such cases, particularly open front display cases, there is a tendency to cut back on usage thereof in recent times. Energy is required for refrigeration of these cases, for antisweat heat during refrigeration, and often for defrosting. Creative con-`,~ 10 cepts have been put forth recently for decreasing energy consumption o refrigeTated display cases. In U. S. Patent 4,026,121, issued May 31, 1977 to Yoshitaka Aokage et al., .:1 a special reverse flow air defrost system is taught.
SUMMARY OF THE INVENTION
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`~-, 15 This invention relates to use of diverted anti-sweat heat electrical energy in a refrigerated display case .l during the defrost mode, and more particularly to diversion of such electrical energy to evaporator defrost heaters.
Electrical controls that switch the refrigerated display from refrigeration mode to defrost mode divert the elec-trical energy normally used for antisweat heaters during the refrigeration mode, to evaporator defrost heaters during the defrost mode.
This development achieves significant energy

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1 conservation. There are two combinations capable of ex-hibiting the energy conserving benefits, one being an open -front refrigerated display case combining reverse -flow air defrost with diversion electrical energy coil defrost, and the other being a door-type display case with diversion electrical energy coil compartment defrost.
The diversion of energy to defrost heat in an open front display case employing reverse flow air defrost causes accelerated defrost, thereby shortening the defrost time period and enabling retention of low food product temp-eratures. Defrost not only occurs more rapidly, but with ~- less wattage.
In the door-type, i.e. so-called reach-in re-frigerated display case or cabinet employing diversion electrical energy defrost, the heat is basically concen-trated and confined to a coil chamber, to allow maintenance of low product temperature as well as less energy consumption.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevational sectional view of an open front refrigerated display case embodiment-of this invention;
Fig. 2 is a schematic electrical diagram for the embodiment in Fig. l;
Fig. 3 is a side elevational sectional view of a door-type refrigerated display case embodiment of this invention; and Fig. 4 is a schematic electrical diagram for the embadiment in Fig. 3.
DESCRIPTION OF THE PREFERRED E~BODIMENTS
OpEN FRONT E~BODIMENT
Referring specifically to Fig. 1, the open front ,.- -~:)68~

1 multiple curtain refrigerated display case 10 constitutes a housing assembly 12 having an access opening 14 over the ' front thereof, rom the ambient air space 16 about the cabinet to the food storage and display space or zone 18 in , 5 the cabinet. This structure is normally placed in a grocery ',, store or supermarket, with display space 18 being divided into sections by a plurality of vertically spaced generally horizontal shelves 20. Display space 18 is conined, by an ,` upper panel OT ceiling Z2, a rear panel or wall 24 to which the shelves are attached, a bottom panel 26 which also -' serves as a support shelf, and a pair of end walls 28.
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~xtending around and adjacent the bottom 26, back ," 24 and top 22 of display area or space 18 is an inner, '~ refriger'ated air flow passage or conduit 30 extending , , . 15 substantially along the length of the case. Passage 30 has an el'ongated upwardly oriented air flow inlet 32 extending along the lower edge of access opening 14, and normally covered by a perforate grill 34 which may be electrically heated to prevent frost formation. Along the upper edge of the access opening 14, opposite inlet 32, is an elongated air flow outlet nozzIe 36 no~mally containing downwardly oriented air directing means such as honeycomb as depicted.
This outlet nozzle is the innermost of a plurality of outlets, preferably three in number. It discharges re-frigerated air down across the open front of the display space to the inlet 32 for recirculati~n about the case.
Located in passage 30, preferably along the lower rear portion thereof, as in the space behind the downwardly forwardly sloping back panel 24, is evaporator coil means 38 containing the' usual tubes and fins, and extending generally along the length of the back panel such that air flow .,- " . - ,.. ....

- ~0~8~21 ., 1 recirculating through the innermost passage of the display must flow through the coil during normal operation. This ' evaporator refrigeration equipment is operably connected to conventional condensing equipment external of the display case in usual fashion, e.g. on the roof of the store, at the rear of the store, or otherwise, as is normally done.
'' Also within passage 30, preferably at the bottom portion of the display case, is a plurality of motor oper-ated fans 4Q spaced lengthwise along the display case and acting as air propelling means to constantly circulate air ' drawn into inlet 32, past these fans 40, through passage 30,including coils 38, out outlet 36, and down across the open front 14 of the display case, i.e. in counterclockwise fashion in the form depicted in Fig. 1 as represented by the solid arrows. T~us, the refrigerated air is recirculated in this fashi'on. Passage 30 is basically defined between the noted panels 26, 24 and 22 forming one side thereof, and a spaced panel' or partition 42 extending around the bottom, back'and top of the case to form the other side of the passage. The refrigerated air flowing through passage 30 not anly forms an enclosing air curtain in the open front of the case, but also a protective envelope around the case.
Partition 42 not only forms the outer wall of inner passage 30, but also forms the inner wall of a second adjacent passage'44 which extends around the bottom, back and top of the case outwardly of passage 30, relative to ,~ display space 18. The ou~er wall of passage 44 is formed by . ..
bottom panel' 46 and back and top panels 46' and 46".
Passage 44 includes an elongated inlet 48 adjacent to and 3Q outwardly of inlet 32, i.e. along the lower edge of the display opening 14. Opposite this upwardly opening inlet 48 , 5-~ 39~1 1 and adjacent the outlet nozzle 36 at the top edge of the display opening 14 is another downwardly oriented elongated outlet nozzle 52 from passageway 44 including air directing means such as honeycomb as depicted. During normal opera-tion, air is circulated through passage 44 by a plurality of motor operated fans 54 preferably in the bottom of the case.
These fans propel air from inlet 48 through passage 44, enveloping the refrigerated air passage 30, and out nozzle 52~ to form a protective guard curtain of air contiguous with and flowing in the same direction with the refrigerated inner air curtain across the open front of the case. This guard curtain returns to outlet 48 for continuous recircu-lation, all as shown by the solid arrows in Fig. l. Typically during normal operation, the temperature of this recir-culated guard air through passage 44 is at a temperature somewhat higher than the temperature of the inner refrig-erated air curtain, but below ambient temperature. It is cooled somewhat by its association with the inner air curtain. Fans 54 are spaced longitudinally along the passage to obtain relatively uniform flow over the length of this passage.
A third curtain of air at ambient temperature is preferably also employed. This curtain is not recirculated about the case, but rather enters the case at the top and exits in front of the rub rai] into the aisle. The ambient air for this third curtain enters the case through a plur-ality of top inlets 56 covered by perforate grids 58 or the like, the air being drawn down in by a plurality of motor operated fans 60 spaced longitudinally along the top of the case length. The air is then propelled downwardly through elongated passage 62 between panels 46" and top panel 64 to ;89Z~
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1 a third elongated outlet nozzle 66 along the top edge of the case, and directed downwardly across the open front of the case outwardly of the inner two nozzles relative to the display space 18.
Nozzle 66 is adjacent nozzle 52 and preferably at a small acute angle relative thereto, with nozzle 52 also preferably being at a relatively small acute angle relative to nozzle 36, all in Xnown fashion. The air flow normally flowing through nozzle 66 is, as indicated by the solid arrows, flowing across the open front or access opening contiguous with the curtain from nozzle 52, and, at the lower edge of the access opening, separating from the intermediate air guard curtain and flowing out over the rub rail into the aisle area of the store for customer comfort as well as adding inertia to the total air curtain flowO
The motors 55 that operate the guard curtain fans 54 are electrically reversible, as are the fans therefor, to enable air to be forced in the opposite direction for passage 44 from that shown in the solid arrows, i.e. in the direction indicated by the dashed arrows during defrost operation. This reverse flow defrost concept is basically set forth in U. S. Patent 4,026,121. Thus, during defrost, : the air is drawn into the intermediate guard nozzle 52, both from the outlet nozzle 66 and also from the ambient at-mosphe~e in front of the case, is circulated around the display9 and is discharged up through the opening 48.
During defrost9 air leaving opening 48 can be drawn down into opening 32, assisted by deflector 49 at the end of opening 48. The panel or wall 42 that separates the con-duits 30 and 44 along the bottom of the display case has an upwardly protruding terminal portion 42a between the open-i ;
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: 1 ings 32 and 48.
The electrical circuit for the open front embodi-ment is shown in Fig. 2 in relation to -four display cabinets or cases. In this illustrative showing, the fourth case is display cabinet 10 of the other drawings. The deErost controls shown include a demand defrost control 150. That is, defrost occurs when the sensor at the cabinet indicates it needs defrost, as detected by a predetermined difference in temperature between the inlet air to the coil and the outlet air from the coil. The control is marketed by Minneapolis Honeywell Co. as "Honeywell Demand Defrost Control CR70A'1. Details are set forth in U. S. Patent No.

3,453,837. A sensor for the control may be placed in each of the multiple of cabinets to cause any one of such to trigger the defrost operation. In such an arrangement, switches 154 and 156, and light 158 would be only on the cabinet on which control 150 is mounted, while each cabinet would hiave a control 152, switch 162 and light 160. Control 152 is marketed by Minneapolis Honeywell Co. as "Dew Point Controller 4-409A11. This demand control may be substituted by a conventional timer-operated defrost control if desired.
The control circuit also includes a control 152 that conserves energy by shutting down the antisweat heaters 168 on the cabinet during defrost, and diverting the power for such to defrost heaters 166 upstream of the coil.
: Control 152 may be, for example, a 1'Honeywell Ant-i-Sweat Control H-40~A". Also incorporated into the illustrated circuit are end lock-out time delay manual switch 154, manual defrost activation switch 156, indicator light 158 preferably red, indicator light 160 preferably yellow, toggle switch 162, and double pole, double throw de:Erost -, . . i.:,. . ; - . i ~6~392~
1 relay 164. The antisweat heaters are connected to the antisweat control 152. This control allows only the re-quired amount of energy to be used by the antisweat heaters to prevent condensation du~ing the refrigeration mode.
S Percent of energy used will vary from 100% at 65~ relative humidity to 0~ at 20% relative humidity.
When the cabinet requires a defrost, control 150 will pu~ the cabinet into defrost automatically. The red indicator light will come on, telling the store personnel the slightly warmer temperature in the cabinet is due to the defrost mode and no~ a malfunction of the refrigeration system. When the cabinet goes into defrost, defrost relay 164 de-energizes all the antisweat~heaters 168 and energizes defrost heaters 166 in front of the evaporator coil to work in combination with the warm air propelled through the passages and coil by reversal of the guard curtain. This diversion of heat shortens the defrost period, protecting the product from deteriorating. If it is desired to put the - cabinet into a manually activated defrost, the two push button switches i54 and 156 are depressed momentarily.
The combination of reverse flow defrost air and heat from diversion energy is highly effective, yet con-serving of energy. In this open front type of case, there would not be sufficient energy from the diverted antisweat requirements alone for defrost. Yet, with the warm ambient air being complemented in this fashion, the results are highly effec~ive.
DOOR-TYPE EMBODIMENT
In Fig. 3 is depicted a reach-in or door-type refrigerated display case 110 employing a conventional housing 1l2 ~hich has a top 11~, back 116, bottom 118, front ::

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1 120 and ends 122. The front includes a plurality of doors lZ4, usually largely glass to allow viewing therethrough, such doors being slidably or hingedly mounted in conven-tional fashion for access to the interior product storage and ~isplay space 126. The food products are supported on a plurality of vertically spaced, generally horizontal shelves 128 mounted in cantilever fashion from the back of the cabinet.
At the top of the cabinet is a space 130 separated from the product storage and display space 126 by a ceiling panel 132. ~ithin space 130 is mounted a refrigeration coil 134 positioned across the passage so that air propelled by a plurality of motor operated fans 136 is forced through the coil for cooling of recirculated air prior to its passage about ~he cabinet. The air flo~s down the back of the cabinet between a back panel 140 and the case back 116, behind the products, through the space below bottom panel 144 and above case bottom 118, and then up in front of the shelyed products, i.e. between the pToducts and front doors 124, such air returning through openings 132' in panel 132, back to the fans 136, in recirculatory fashion. Adjacent glass doors 124 are positioned conventional vertically oriented fluorescent lamps 125 for illumination of the display space. Re~rigeration coil 134 is in cooperative relationship with a compressor and condensor unit ~not shown~ located elsewhere through suitable conduits 135 in normal fashion.
On the face of the doors is mounted antisweat heaters which typically include door perimeter heaters 150 3Q (Fig. 4)~ glass door heaters 152, mullion heaters 154, and case perimeter heater 156. Such heaters are typically -10~

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1 resistance heaters, and serve to prevent condensation forming on the noted surfaces.
In accordance with this invention, there is located immediately adjacent coil 134, therebeneath, a plurality of defrost heater elements 160 ~Figs. 3 and 4) operated alternately with the noted antisweat heaters.
Temperature control 164, pressure control switch 166 and a t~imer subassembly 168 govern these heaters as explained hereinafter. The timer subassembly includes ~imer motor TM
which operates a normally closed timer swi~ch A and a normally open timer switch B, and includes a solenoid 170.
A single pole double throw relay 174 has a coil I, and a switch 176 normally closed at terminal H and normally open at terminal J for alternately operating the antisweat , heaters and the evaporator defrost heaters, respectively.
An evaporator defrost termination and fan delay control subassembly 180 includes a switch 182 normally closed to terminal C and normally open relative to terminal L. When closed to terminal C, the switch completes a circuit to coil 2Q D in single pole double throw relay 184, the switch 186 of which i5 normally closed to terminal E and normally open to terminal F. Terminal E and the switch thus complete a - circuit to the electrical motors G for the evaporator fans 136. For clarity, the operational sequence is as follows:
Refrigeration Mode 1. Timer switch "A" is closed.
2. Timer switch "B" is open.
3. Defrost termination switch is in contact "C"
:, position.

4. ~elay coil IIDIt is energized, halding switch . .
~; 186 in closed position at contact "E".

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1 5. ~vaporator fans run continuously until the de-frost period.
6. Glass door and rame antisweat heaters are energized through one side of relay 174, terminal "H", from a separate 115 volt circuit as depicted.
DeErost Mode 1. Defrost timer switch "A" is open and "B" is closed, being mechanically activated by the timer at a preset time.
2. Opening of switch "A" de-energizes coil "D", putting relay in "F" pasition stopping fan motors "~".
3. Closing of switch "B" energizes coil "I" in relay 174.
4. Energizing coil "I" puts relay in "J" position that energizes defrost heaters 160 and de-energizes anti-sweat heaters 15Q, 152, 154, and 156. The heat given off by ,j,.. .
the defrost heaters is confined within the space 130 to maximize defrost action with less energy consumption.

5. When the sensing bulb 190 of defrost term-ination control reaches the preset temperature (usually about 45 degrees F.~ the control switch takes the position "L".

6~ This activates solenoid 170 which returns the system to the refrigeration mode.
Resumption of Refrigeration Mode 1. Opening of switch "B" de-activates coil "I"
and returns switch of relay 176 to "H" position. This .
terminates the heat in the defrost heaters and re-energizes the antisweat heaters.
2. When the sensing bulb of the defrost term-~-~ inatian control reaches about ~20 degrees F. the switch , . .

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1 returns to position "C".
3. This reactivates the coil "D" and the relay switch returns to switch position "E" starting up the fans.
There is preferably an approximately ~hree minutes delay in starting up of the fans after refrigeration is started to allow proper lowering of the coil temperature before air flow through it, to avoid raising of the temperature in the product display and storage space.
In this door-type of display case, the energy requirements for antisweat heat are quite high, causing the diversion use thereof to be sufficient for defrost of the coil with confinement of the heat to the small coil chamber above the display space, with the fans no~ operating. The melted frost and ice rom the coil flow into a trough 190 lS for flow out plpe 192 to drain.
Conceivably details of these two combination embodiments could be altered within the concept presented, the scope of the invention being set forth by the following claims and the reasonable equivalents thereto.
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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

A refrigerated display case operable in refrig-eration mode and in defrost mode, and having a product storage space, evaporator cooling means for cooling air, air propelling means for circulating air through said evaporator cooling means and into said product storage and display space; electrical control means operably associated with said air propelling means for controlling air flow about said product storage and display space; said electrical control means having connection means for electrical power supply; electrical resistance antisweat heaters for said display case and a first electrical circuit therefor;
electrical resistance heater means for said evaporator means and a second electrical circuit therefor; both said first and said second electrical circuits being connected to said electrical control means; and said electrical control means being operable to electrically actuate said first electrical circuit with said antisweat heaters and deactivate said second electrical circuit with said defrost heaters during said refrigeration mode and to activate said second elec-trical circuit with said defrost heaters and deactivate said first electrical circuit with said antisweat heaters during said defrost mode to cause antisweat energy to be diverted to use for defrost.

A refrigerated display case operable in refrigeration mode and in defrost mode, and having a product display and storage space, evaporator cooling means for cooling air, air propelling means for circulating refrigerated air in one direction through said evaporator cooling means and about said display space and for circulating defrost air in the opposite directlon through said evaporator cooling means;
electrical control means operably associated with said propelling means for causing refrigerated air flow in said one direction during the refrigeration mode of said case and ambient air 10w in said opposite direction during the defrost mode of said case; said electrical control means having connection means or electrical power supply; elec-trical resistance antisweat heaters for said display case, and a first electrical circuit therefor; electrical re-sistance heater means for defrosting said evaporator means, and a second electrical circuit therefor; both said first and said second electrical circuits being connected to said electrical control means; and said electrical control means being operable for activating said first electrical circuit with said antisweat heaters and deactivating said second electrical circuit with said defrost heaters during said refrigeration mode, and for activating said second elec-trical circuit with said defrost heaters and deactiva-ting said first electrical circuit with said antisweat heaters during said defrost mode, whereby antisweat energy is diverted for defrost in combination with ambient air flow.

The refrigerated display case in claim 2 being an open front display case having first conduit means for a recirculating refrigerated inner air curtain and second conduit means for an adjacent guard curtain during the refrigeration mode, said ambient air flow in said opposite direction in the defrost mode being heated by said defrost heaters prior to passage through said evaporator cooling means.

A refrigerated display case operable in refrig-eration mode and defrost mode, and having a product storage space, evaporator cooling means for refrigerating air, air propelling means for circulating refrigerated air through said evaporator cooling means and into said product storage space; electrical control means operably associated with said propelling means for controlling air flow to deactivate said propelling means during said defrost mode and reacti-vate said propelling means during said refrigeration mode;
electrical resistance antisweat heaters for said display case and a first electrical circuit therefor; electrical resistance heater means for said evaporator means and a second electrical circuit therefor; both said first and said second electrical circuits being connected to said elec-trical control means; and said electrical control means being operable for activating said propelling means and said first electrical circuit with said antisweat heaters and deactivating said second electrical circuit with said defrost heaters during said refrigeration mode and for activating said second electrical circuit with said defrost heaters and deactivating said propelling means and said first electrical circuit with said antisweat heaters during said defrost mode to cause antisweat energy to be diverted to defrost usage.

The refrigerated display case in claim 4 wherein said case includes an upper chamber above said product storage space housing said evaporator cooling means and said air propelling means, such that, during said defrost mode, heat from said defrost heaters is basically confined to said upper chamber.

The refrigerated display case in claim 5 wherein said defrost heaters are located immediately beneath said evaporator cooling means.