US3333437A - Frost collector for refrigerated display cases - Google Patents

Frost collector for refrigerated display cases Download PDF

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Publication number
US3333437A
US3333437A US476808A US47680865A US3333437A US 3333437 A US3333437 A US 3333437A US 476808 A US476808 A US 476808A US 47680865 A US47680865 A US 47680865A US 3333437 A US3333437 A US 3333437A
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United States
Prior art keywords
frost
air
collector
duct
access opening
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US476808A
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English (en)
Inventor
James H Brennan
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Newfrey LLC
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Newfrey LLC
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Filing date
Publication date
Application filed by Newfrey LLC filed Critical Newfrey LLC
Priority to US476808A priority Critical patent/US3333437A/en
Priority to GB53003/65A priority patent/GB1098430A/en
Priority to SE2343/66A priority patent/SE305004B/xx
Priority to DE19661501037 priority patent/DE1501037A1/de
Application granted granted Critical
Publication of US3333437A publication Critical patent/US3333437A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/06—Removing frost
    • F25D21/08—Removing frost by electric heating
    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47F—SPECIAL FURNITURE, FITTINGS, OR ACCESSORIES FOR SHOPS, STOREHOUSES, BARS, RESTAURANTS OR THE LIKE; PAYING COUNTERS
    • A47F3/00—Show cases or show cabinets
    • A47F3/04—Show cases or show cabinets air-conditioned, refrigerated
    • A47F3/0439—Cases or cabinets of the open type
    • A47F3/0443—Cases or cabinets of the open type with forced air circulation
    • A47F3/0447—Cases or cabinets of the open type with forced air circulation with air curtains

Definitions

  • This invention relates generally to refrigerated display cases of the commercial type, used in supermarkets and similar establishments for the purpose of holding a large quantity of refrigerated foods in an attractively displayed arrangement and at a temperature below freezing.
  • the invention has reference to a device usable either as a built-in component of, or as a separate accessory to, a case of the type described, and serving as a collector of frost that would otherwise be deposited directly upon the refrigerating mechanism of the display case.
  • frost or snow is found to take place on various surfaces and at various points which serve to provide a nucleus, or crystallization initiating, or seeding point or surface. Moreover such accumulations take place even though the points or surfaces where snow or frost deposit are at temperatures which are the same or even higher than the temperature of the super-cooled moisture or the crystal containing air coming into contact therewith.
  • the temperatures at which the formation of frost or snow will occur must be below freezing (32 F.) but tend to vary considerably depending upon numerous conditions which are little understood but are discussed at length in an article by B. J. Mason appearing in the Scientific American, January 1961 at pages 120 to 131 and on pages 119 to 150 of a book entitled, The Art and Science of Growing Crystals, by J. J. Gilman, published by John Wiley & Sons, Inc.
  • the form of the crystals deposited is subject to wide variation.
  • the crystals produced are generally in the form of long fine needles which project outwardly from the surfaces or points on which they accumulate so as to obstruct the passages and limit the flow of air through the passages.
  • the main object of the present invention is to reduce the number and/or the individual length of the defrost periods mentioned above.
  • I provide a device mountable in the return air flue of the low temperature refrigerated display case, which includes a grid composed of a metal frame onto which an electrical resistance element is laced. The resistance element and the frame thus cooperate to provide a grid means, of fiat, generally rectangular configuration, adapted to be mounted in a slightly tilted position in the return air flue, in contact with opposite walls of said flue.
  • this device extends across the path of air moving through the line, in a position such as to require that all the air that is so moved be channeled through interstices or openings in the grid, before impinging upon the re-frigerated coiling surfaces of the cooling mechanism of the case.
  • the low temperature return air passes through the openings of the grid, supercooled moisture and ice crystals with which the air is laden are caused to -be deposited upon the grid in the form of frost.
  • the frost so deposited upon the grid is frost that would otherwise have been deposited upon the refrigerated coiling surfaces of the cooling mechanism, and hence there is a substantial reduction in the build-up of frost or snow accumulation upon the cooling unit itself.
  • the separate defrosting of the collector means briefly described above may be and preferably is automatically responsive to a timing device or the like, and is designed to defrost the collector to, but not beyond, a point where the frost actually changes state and liquefies.
  • the bulky and needle-like frost or ice crystals are caused to melt and collapse into the form of droplets of water which tend to adhere to the wires or elements of the grid.
  • the frost obstruction developed within the return air duct is thereby eliminated without vaporizing the liquid or causing it to migrate or be transferred into contact with the coils, fins or surfaces of the evaporator to form ice or frost thereon.
  • the resultant warming of air in the circulating air pattern is effective to completely clean the frost collecting device as well as the refrigerated coiling surfaces, with the liquid condensate from both of these assemblies being drained off in the usual manner.
  • frost collector To incorporate in the construction of the frost collector a design that will produce a uniform build-up of frost on the deposition surfaces of the collector, in such a way as to maintain maximum flow of air through the interstices of the collector until said build-up has progressed to a point where it covers substantially the entire surface area of the grid;
  • FIG. 1 is a transverse sectional view through a typical, conventioal low temperature refrigerated display case, with the frost collector constituting the present invention being mounted in operating position therein, said frost collector being shown in end elevation;
  • FIG. 2 is a sectional view substantially on line 2-2 of FIG. 1;
  • FIG. 3 is an enlarged perspective view of the device, portions being broken away, the wiring of the device constituting the present invention being illustrated partly diagrammatically;
  • FIG. 4 is an enlarged transverse sectional view through the device substantially on line 44 of FIG. 3;
  • FIGS. 5 and 6 are fragmentary, transverse sectional views through the return air flue, showing the manner in which frost progressively accumulates upon the collector.
  • the invention is particularly well adapted for use on multi-deck equipment operating at temperatures below freezing, since such equipment involves the handling of especially large volumes of air.
  • the invention is adapted for use on any of various types of refrigerated display equipment, which operates at temperatures below freezing, and by way of example has been shown in FIG. 1 as incorporated in a case of the type used for the merchandising of frozen foods and ice cream. It will be understood that this showing is intended to be merely illustrative of a wide variety of. low temperautre refrigerated cases in which the invention can be readily incorporated.
  • the display case has been generally designated 10 and has an upwardly opening food compartment 11 defined by front, back, bottom, and end walls 12, 14, 16 and 18 respectively.
  • Inwardly from the front, back, and bottom walls are flue walls 20, 22 and 24 respectively, defining a duct 25 extending continuously .along the front, bottom and back walls, between said walls and the food compartment 11.
  • This duct includes the usual return air flue 26, bottom flue 28, and back or outlet flue 30.
  • air circulates within these flues, in a continuous, closed air pattern, with said air being discharged from the upper end of the outlet flue 30, for movement across the open top of the compartment 11 as shown at 32, the return air entering the return air flue 26 at the upper end thereof, and moving downwardly for recooling by the refrigerating unit mounted in the bottom flue.
  • a ticket moulding 34 projecting forwardly from the rear sill 35 above outlet louvers 36, through which the cooled air is discharged for movement across the open side of the compartment.
  • the usual front trim moulding 38 having inlet 40 for the return air entering the return or intake air flue 26.
  • the desired rigidity is imparted to the walls of the various flues by such means as upper and lower Z-brackets 42, 44 respectively. These are held in position in any suitable manner, and are swiftly and easily inserted or removed.
  • a refrigerating mechanism generally designated 45 including in the illustrated example evaporators 46, 48, between which is provided a fan 50 for maintaining air circulation in the desired pattern.
  • the refrigerating mechanism employed is of such size or capacity, or is so operated that the temperature maintained within the food compartment and the temperature of the .air circulated about said compartment and through the return air flue 26 by the fan 50 are low temperatures which term as used herein refers to temperatures below freezing (32 F.).
  • the conventional drain pan 52 which extends longitudinally of the display case, and which has the outlet 54.
  • a rubber sleeve 56 communicating between the bottom flue 28 and the space below the insulated bottom wall 16, to provide a conduit through which the lines extending to and from the refrigerating mechanism 45 can be led. Said lines are not shown in the illustrated example, since they are not necessary to description of the invention and the parts of the display case cooperating therewith.
  • a raceway 58 extending longitudinally of the display case to provide a conduit for the electrical cable or cables 60 needed to wire the display case.
  • Grid 63 comprises in its principal features of construction, a frame generally designated 64, and a resistance element.
  • the frame 64 is of generally rectangular configuration, and can be of any desired height and length, according to the size of the particular display case in which the collector is to be used, as well as the type of such display case. It is mainly important that the length of the frost collector be such as to cause all or the greatest part of air, passing through the return air flue, to be channeled through interstices or openings defined in the grid 63.
  • I provide a series of uniformly spaced transverse rails 66 formed of rigid rod stock. Spot-welded or otherwise fixedly secured to the rails 66, in crossing relation thereto, are longitudinal rails 68.
  • the grid also includes a resistance element.
  • the resistance element itself constitutes a deposition surface for frost, and the various courses of the laced element cooperate with one another and with the frame 64 in defining openings 71 through which air may pass as it is moved through the return air flue.
  • a series of uniformly spaced metal pins 72 secured to one of the end rails 66 (see FIG. 2), and projecting outwardly from said one rail to provide means about which the element can be laced.
  • the lacing proceeds just below the upper one of the rails 68.
  • the resistance element 70 is extended along one face of the frame to the other end rail 66, after which it is coiled about the rail 66 remote from pins 72, in an inclined path as shown at 73 in FIG. 4. Then, the resistance element is extended back along the opposite face of the frame, and is coiled about the rail 66 having the pins 72.
  • the resistance element 70 provided upon the opposite ends of the resistance element 70 are rubber-covered electrical connectors 74, permitting connection of the ends of the element to the opposite leads 75 of (FIG. 1) an insulated conductor 76.
  • the rubber sleeve 56 is utilized as a passage whereby the conductor 76 can extend out of the duct, and into the raceway 58.
  • the conductor is connected in circuit (FIGS. 1 and 3) with a timer 78 or other automatic control device.
  • the timer has connections 79 permitting it to be attached to a source of electrical power.
  • connections 79 are spliced or otherwise electrically connected to the cable 60 of the display case, at a location such that the timer is preferably unaffected by, and does not itself affect electrical devices within the case to which power is supplied by means of the cable 60'.
  • the device In use of the device, it is readily installed in a low temperature refrigerated display case that is already in use, merely by removing the upper Z-brackets 42, after access thereto is provided by removal of any necessary trim such as the moulding 38.
  • the grid will automatically assume an inclined position as shown in FIG. 1, in which the grid is in contact, .at its upper and lower ends, with wall 12 and wall 20, respectively.
  • the grid thus extends across the return air flue, in a position such that for all practical purposes, all air that is moving through the return air flue must pass through the grid openings.
  • the periodic defrosting of the collector 62 necessitated by frost deposition on the grid 2 in excessive degree, is effected without necessity of shutting down the refrigerating cycle or interfering in any other way with the normal cooling and circulation of the air within the case. 1 accomplish this by the provision of any suitable automatic control on the frost collector, as for example the timer 78.
  • I may defrost the collector on the average of once every hour, for a period of about two minutes.
  • the resistance element may, for example, be supplied with current in an amount equal to 10 watts per foot of the resistance element, or in a typical frost collector of the type illustrated which is 4 feet in length the resistance element may be supplied with 900 watts of current at 212 volts.
  • the resistance elements of such a frost collector operated as described, in a display case loaded with frozen food, and contacted by air in the return air duct having a temperature of 0 F., was found to attain temperatures as indicated in the following table:
  • the defrost means (not shown) of the refrigerating unit or mechanism 45 operates in the usual fashion, although as previously noted herein such operation will be less frequent when the invention is used. It is considered that the defrost means of the refrigerating mechanism will operate every four or six hours, at a typical installation for perhaps twenty-two to thirty minutes. When this operation occurs, air circulated in the duct is increased in temperature to a predetermined maximum at the return air duct intake openings 40, as for example 47 F.
  • This provides an air curtain extending across the open side of food compartment 11, which is lower than ambient, so as to minimize the migration of ambient air into the pattern.
  • this temperature is such as to completely clean the frost collector grid, as well as the coiling surfaces of the refrigerating mechanism 45, of all accumulated moisture. Said moisture drains off both from the grid and from the refrigerating mechanism components, in to the pan 52.
  • the deposition of the frost F upon the grid proceeds in a manner such as to maintain interference with free air movement at a minimum, until the deposition of the frost occurs to a point such as to make defrosting advisable.
  • the first portion of the collector grid that is impinged upon by super-cooled moisture and ice crystal containing air entering the return flue is the top portion thereof. Accordingly, fro-st or snow is deposited upon this top portion, and builds up to a predetermined thickness, more or less. When this occurs, the openings at the top of the device will either be completely closed or will at least be reduced substantially in size by the bulky needle-like crystals which have accumulated on the upper portion of the frost collector. As a result, air passing through the return duct now tends to move below the 7 area in which the frost has accumulated, and still passes freely through the openings of grid areas that are still unaffected.
  • frost accumulation tends to move downwardly, progressively, from the top, as shown by a comparison of FIGS. and 6. As it moves downwardly, it builds up to the predetermined thickness before additional frost of any consequence is deposited upon other, lower areas of the grid through which air still passes freely. This progressive accumulation of frost continues, until eventually the passage of air through the openings of the grid is impeded to an excessive degree, and would affect adversely the efliciency of the refrigerating action and the accompanying air circulation. At this time, the timer, which is pre-set to close a circuit to the resistance element at what is found to be the most desirable time according to the particular installation, operates to close said circuit.
  • the device is shown as a selfcontained, quickly installable accessory to refrigerated cases already in use. It could, with equal case, be built into a refrigerated display case, and in fact when built in in this way, need not be changed in design in any way, should the manufacturer so prefer. As an accessory, it is installed quickly, by relatively unskilled help. In fact, it is quite possible to provide a conventional attachment plug cap upon the conductor 76, and plug the device into a near-by convenience outlet, without even having to splice the conductor into the wiring of the display case.
  • frost collector embodies a frame located in an inclined position within said return air duct and has a plurality of vertically spaced substantially horizontal electrical resistance elements thereon to which said drops of water tend to cling.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Cold Air Circulating Systems And Constructional Details In Refrigerators (AREA)
  • Resistance Heating (AREA)
  • Defrosting Systems (AREA)
  • Freezers Or Refrigerated Showcases (AREA)
US476808A 1965-08-03 1965-08-03 Frost collector for refrigerated display cases Expired - Lifetime US3333437A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US476808A US3333437A (en) 1965-08-03 1965-08-03 Frost collector for refrigerated display cases
GB53003/65A GB1098430A (en) 1965-08-03 1965-12-14 Frost collector for refrigerated display cases
SE2343/66A SE305004B (enrdf_load_html_response) 1965-08-03 1966-02-23
DE19661501037 DE1501037A1 (de) 1965-08-03 1966-04-29 Frostfilter fuer Kuehltruhen

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US476808A US3333437A (en) 1965-08-03 1965-08-03 Frost collector for refrigerated display cases

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US3333437A true US3333437A (en) 1967-08-01

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US476808A Expired - Lifetime US3333437A (en) 1965-08-03 1965-08-03 Frost collector for refrigerated display cases

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US (1) US3333437A (enrdf_load_html_response)
DE (1) DE1501037A1 (enrdf_load_html_response)
GB (1) GB1098430A (enrdf_load_html_response)
SE (1) SE305004B (enrdf_load_html_response)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3371503A (en) * 1966-11-23 1968-03-05 Clark Equipment Co Refrigerant line grille structure
US3381494A (en) * 1966-10-27 1968-05-07 Clark Equipment Co Frost collector evaporator coil
JPS5380852A (en) * 1976-12-27 1978-07-17 Fuji Electric Co Ltd Flat type open show case
US4106305A (en) * 1976-07-07 1978-08-15 Ibrahim Fayez F Open well type refrigerated display case with reverse flow of air bands
US4199957A (en) * 1978-06-20 1980-04-29 Harker Co., Ltd. Evaporator assembly
US4265092A (en) * 1979-12-26 1981-05-05 Tyler Refrigeration Corporation Refrigerated display case using air defrost with supplemental heater
US4320631A (en) * 1981-01-23 1982-03-23 Emhart Industries, Inc. Air defrost for low-bed refrigerated display cases, utilizing sill-mounted auxiliary fan
US4750335A (en) * 1987-06-03 1988-06-14 Hill Refrigeration Corporation Anti-condensation means for glass front display cases
US5709096A (en) * 1995-10-11 1998-01-20 Sanyo Electric Company, Ltd. Defrosting device for a low temperature display case
US20050061015A1 (en) * 2003-09-19 2005-03-24 Ingley Herbert A. System for trapping airborne water in cooling and freezing devices
US20050223729A1 (en) * 2002-03-19 2005-10-13 Mayekawa Mfg. Co., Ltd. Low temperature zoning formation system for holding freshness of food
US20060207281A1 (en) * 2005-03-15 2006-09-21 Sanden Corporation Showcase

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE450045B (sv) * 1981-09-29 1987-06-01 Electrolux Ab Frostmotverkande anordning vid frysmobel

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2663158A (en) * 1951-05-22 1953-12-22 Ernest E Sanders Frozen food cabinet
US2923135A (en) * 1956-11-23 1960-02-02 Gen Motors Corp Open top refrigerator display case
US3063256A (en) * 1961-08-17 1962-11-13 Lamb Frank Gilbert Upright refrigerator showcase
US3096629A (en) * 1961-04-05 1963-07-09 Gen Motors Corp Frostless freezer
US3233424A (en) * 1964-08-14 1966-02-08 Dual Jet Refrigeration Company Frost collecting means for refrigerated structures
US3243971A (en) * 1964-08-14 1966-04-05 Dual Jet Refrigeration Company Means for reducing frost build-up

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2663158A (en) * 1951-05-22 1953-12-22 Ernest E Sanders Frozen food cabinet
US2923135A (en) * 1956-11-23 1960-02-02 Gen Motors Corp Open top refrigerator display case
US3096629A (en) * 1961-04-05 1963-07-09 Gen Motors Corp Frostless freezer
US3063256A (en) * 1961-08-17 1962-11-13 Lamb Frank Gilbert Upright refrigerator showcase
US3233424A (en) * 1964-08-14 1966-02-08 Dual Jet Refrigeration Company Frost collecting means for refrigerated structures
US3243971A (en) * 1964-08-14 1966-04-05 Dual Jet Refrigeration Company Means for reducing frost build-up

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3381494A (en) * 1966-10-27 1968-05-07 Clark Equipment Co Frost collector evaporator coil
US3371503A (en) * 1966-11-23 1968-03-05 Clark Equipment Co Refrigerant line grille structure
US4106305A (en) * 1976-07-07 1978-08-15 Ibrahim Fayez F Open well type refrigerated display case with reverse flow of air bands
JPS5380852A (en) * 1976-12-27 1978-07-17 Fuji Electric Co Ltd Flat type open show case
US4199957A (en) * 1978-06-20 1980-04-29 Harker Co., Ltd. Evaporator assembly
US4265092A (en) * 1979-12-26 1981-05-05 Tyler Refrigeration Corporation Refrigerated display case using air defrost with supplemental heater
US4320631A (en) * 1981-01-23 1982-03-23 Emhart Industries, Inc. Air defrost for low-bed refrigerated display cases, utilizing sill-mounted auxiliary fan
US4750335A (en) * 1987-06-03 1988-06-14 Hill Refrigeration Corporation Anti-condensation means for glass front display cases
US5709096A (en) * 1995-10-11 1998-01-20 Sanyo Electric Company, Ltd. Defrosting device for a low temperature display case
US20050223729A1 (en) * 2002-03-19 2005-10-13 Mayekawa Mfg. Co., Ltd. Low temperature zoning formation system for holding freshness of food
US7322204B2 (en) * 2002-03-19 2008-01-29 Mayekawa Mfg. Co., Ltd. Low temperature zoning formation system for holding freshness of food
US20050061015A1 (en) * 2003-09-19 2005-03-24 Ingley Herbert A. System for trapping airborne water in cooling and freezing devices
WO2005028974A1 (en) * 2003-09-19 2005-03-31 University Of Florida System for trapping airborne water in cooling and freezing devices
US6925819B2 (en) 2003-09-19 2005-08-09 University Of Florida Research Foundation, Inc. System for trapping airborne water in cooling and freezing devices
US20060207281A1 (en) * 2005-03-15 2006-09-21 Sanden Corporation Showcase

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SE305004B (enrdf_load_html_response) 1968-10-14
GB1098430A (en) 1968-01-10
DE1501037A1 (de) 1969-10-23

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