METHOD OF USING A DROP-IN PASSIVE THERMAL INSERT FOR FOOD SERVICE COUNTERS
Passive temperature control is provided to vessels too tall to be stored in a shallow, temperature-controlled tray or basin by a vertically oriented thermally-conductive tube. In one embodiment, an insulative collar covers the tray and insulates portions of the tube that extend above the top of the tray. Optional heat sinking fins and air convection holes increase heat transfer between the tube and the tray.
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This patent application is a divisional of application Ser. No. 12/329,795, which was filed on Dec. 8, 2008, and which is entitled, “Drop-In Passive Thermal Insert for Food Service Counters.”
FIELD OF THE INVENTIONThis invention relates to a thermally-insulated canister, usable to vertically extend a heated or refrigerated volume of heated or refrigerated food-serving tray.
BACKGROUND OF THE INVENTIONIt is well known that temperature gradients exist within food-serving trays 12. Room air currents mix with air in the tray 12, which tend to warm the top of a refrigerated tray and cool the top of a heated tray. The air temperature inside and near the top 16 of the tray 12 will almost always be different than the air temperature inside and at the bottom of the tray 12. Food storage trays 12 are therefore less than ideal for storing perishable foods for long periods of time, especially when ambient room air temperatures are high and/or when room air currents are relatively brisk. Upper portions 22 of tall vessels 20 are not refrigerated at all.
Some restaurants, sandwich shops and food services prepare foods that include made-to-order sandwiches, ice cream and pizza. Many such establishments add condiments to their products, examples of which can include but are not limited to, whipped cream, salad dressing, cheeses and mayonnaise. They usually add such condiments using well-known, hand-held dispenser squeeze bottles.
Many condiments need to be kept refrigerated in order to preserve their freshness. Dispensers from which such condiments are dispensed therefore also need to be refrigerated.
While restaurants and food service providers that add perishable condiments to food products know that some condiments need to be kept refrigerated, capital equipment costs, operating expenses and food product preparation time constraints can force many restaurants and food service providers to forego properly refrigerating condiment dispensers 20. Some restaurants and food services have taken to storing hand-held condiment dispensers in a refrigerated tray 12 when the condiment dispensers 20 are not being used in order to keep the dispensers somewhat chilled but nevertheless accessible.
Refrigerated food storage trays 12 used in prior art food service counters 10 are too shallow to properly refrigerate tall, hand-held condiment dispensers 20. Even if the trays 12 were as deep as a condiment dispenser is tall, the temperature gradient inside the tray is nevertheless inadequate to properly chill the top, upper-most part 22 of a tall condiment dispenser 20 because of the temperature gradient that exists in the trays 12. Lowering the nominal tray temperature so that the top portion 22 is kept at or below a proper condiment storage temperature might mean that the bottom portion of a tray goes below 32° F., which would freeze contents at the bottom portion 24 of a dispenser 20. An apparatus and method for assisting the refrigeration of a elongated, upright, hand-held dispensers in a food storage tray 12 would be an improvement over the prior art.
The top 16 of a food storage tray 12 is usually left open, as shown in
The canister 30 has a height that is greater than the depth of the tray 12, the tray depth being considered herein to be equal to, or substantially equal to, the distance between the open top 16 of the tray 12 and the bottom 19 of the tray. As set forth below, the portion of the canister 30 above the top 16 of the tray 12 allows the canister 30 to provide passive temperature control, i.e., refrigeration or heating, to the upper portion 22 of the vessel 20 stored inside the tube, the upper portion 22 of the vessel 20 being considered to be the portion of the vessel above the top 16 of the tray 12.
The tube forming the canister 30 shown in the figures has an open interior that defines an open volume that accepts a vessel 20, such as the aforementioned hand-held condiment dispenser. (Vessel and condiment dispenser are hereafter used interchangeably.) The height of the canister 30 is greater than the depth of the tray 11, but less than the height of a vessel 20 to be passively refrigerated in order to allow the vessel 20 to be grasped for removal from the canister 30.
As can be seen in
Radiating and/or conducting heat from the lower portion 36 of the canister 30 into the tray 12 causes the temperature of lower portion 36 of the canister 30 to drop, relative to the temperature of the upper portions 38 of the canister 30. Because the canister 30 is constructed of thermally-conductive material, latent heat in the initially warmer upper portion 38 of the canister 30 is conducted downward, through the canister material to the colder, lower portion 36 of the canister 30 where it, too, is radiated and/or conducted into the tray 12.
When heat is conducted from the upper portion 38 of the canister 30 to the lower portion 36, the temperature of the upper portion 38 of the canister 30 will decrease, relative to its surroundings. A decreased temperature of the upper portion 38 of the canister 30 allows the upper portion 38 of the canister 30 to absorb heat radiated from the upper portion of a relatively warmer vessel 20 placed inside the canister 30. The canister 30 is thus able to absorb heat radiated from a vessel 20 inside the canister and re-radiate (as well as conduct) the heat from the vessel 20 into the tray 12, so long as the temperature of a vessel inside the canister 30 is greater than the temperature of the canister 30 itself. Heat radiated from a vessel 20 inside the canister 30, including in particular heat radiated from a vessel at elevations of the vessel that are above the top 16 of the tray 12, is thus captured by the canister 30, conducted downward through the canister 30 and radiated and/or conducted into the tray 12 for absorption by a refrigeration device, not shown. The structure, geometry and material of the canister 30 thus provide a passively temperature-controlled space above the top 16 of the tray 12 and above the top of a food service counter 10 in which a tray might be installed and operated with.
The canister 30 shown in the figures is embodied as a cylindrical, aluminum tube. It has an open top 32 to receive a cylindrical, hand-held condiment dispenser 20. In an alternate embodiment, the opposite end of the cylinder, i.e., the bottom 39 of the tube, is closed off to form a flat, thermally-conductive bottom that can either rest on or be suspended above the bottom 19 of the tray 12. The increased area of a flat, closed-off bottom enhances heat conduction between the canister 30 and the tray 19, but requires additional material and hence additional fabrication cost. A closed-off bottom can also make cleaning the canister 30 more difficult.
The canister 30 has an interior cross sectional shape that preferably conforms to and which is just slightly larger than the exterior shape or cross section of a vessel 20, the temperature of which is to be passively controlled. Matching the interior shape and size of the canister 30 to the exterior shape and size of a vessel to be passively refrigerated improves passive temperature control by tightening the thermal coupling between the two bodies. Another embodiment uses a canister 30 having an inside diameter that allows the exterior surface of the vessel 20 to physically contact the insider surface of the canister and remain in physical contact therewith in order to facilitate conductive heat transfer between the vessel 20 and the canister 30. Alternate embodiments of the canister 30 can have non-circular cross sections that can be square, rectangular, oval or elliptical, triangular or any irregular closed polygon, but as set forth above, the cross section of the canister 30 preferably matches, and is only slightly greater than the cross section of a vessel to be passively refrigerated.
In
The canister embodiments described above illustrate structures that vertically extend temperature-controlled environments provided within a relatively shallow, temperature controlled food storage trays. As was set forth above, however, room air and convection currents can create temperature gradients with a tray 12 that can adversely affect the performance and operation of the embodiments set forth above.
The collar 70 shown in
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As used herein, a drop-in passive thermal insert, which is also referred to herein as a canister, should be considered to include any thermally-conductive structure that can enclose a vessel taller than a temperature-controlled food storage tray and which exchanges heat between itself and the tray. Those of ordinary skill in the art will recognize that a drop-in passive insert, specifically including the embodiments depicted in the figures and described above, can be advantageously used with a food service counter, as shown in
While the preferred embodiment of the canister has been described with respect to passive refrigeration, those of ordinary skill in the art will recognize that the canisters can also be used with hot trays, with or without the aforementioned insulating collars 70, the difference between them being only the direction of heat flow. When the passive canisters described above are used with a cold tray, heat flows in the direction shown in
It should be apparent from the foregoing description that a method has been described for storing and passively controlling the temperature of a hand-held condiment dispenser, having a height greater than the depth of a temperature-controlled tray. In a first step of such a method, a thermally-conductive tube of any of the aforementioned shapes is placed inside a temperature-controlled food storage tray, which is also provided to a temperature-controlled food service counter as shown in
In a second step, a condiment dispenser or other vessel is placed inside the open volume of the thermally-conductive tube, which is also referred to herein as a canister. Since the temperature through-out the interior of the canister, is at or near the temperature of the temperature-controlled tray, over time, the temperature of a vessel placed into the canister will eventually reach a temperature equal to or nearly equal to the temperature of the tray. As used herein, such a step is considered to be temperature equalization.
In another step, which can take place before or after the second step, the temperature controlled food storage tray is covered and portions of the tube that extend above the open top of the tray are thermally-insulated by an insulating collar around the tube and which covers the tray. A condiment dispenser or other vessel can thereafter be provided more effective temperature control (heating or refrigeration) than would otherwise be possible by simply placing a dispenser or vessel into a temperature controlled tray, too shallow to properly heat or refrigerate the vessel. Finally, a food product, such as a sandwich, pizza or an ice cream can be served to a consumer from a food service counter, such as the one depicted in
The foregoing description and various embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
Claims
1. A method of controlling the temperature of a vessel stored in a temperature-controlled tray, the temperature-controlled tray having a first height, the vessel having a second height greater than the first height, said method comprising the steps of:
- placing a thermally-conductive metal tube into the temperature-controlled tray, the metal tube having a height greater than the first height and less than the second height, the tube also having an interior cross sectional shape and configured to stand substantially upright into the temperature-controlled tray;
- placing a dispenser having an exterior shape into the metal tube;
- wherein the interior cross sectional shape of the metal tube conforms to but is larger than the exterior shape of the dispenser; and
- wherein the metal tube passively transfers heat between the dispenser in the metal tube and the temperature-controlled tray.
2. The method of claim 1, wherein the temperature-controlled tray is a refrigerated tray and wherein the dispenser is a food dispenser.
3. The method of claim 1, wherein the temperature-controlled tray is a heated tray and wherein the dispenser is a food dispenser.
4. The method of claim 1, including the step of providing the temperature-controlled tray to a food service counter.
5. The method of claim 1 including the step of providing a thermally-conductive fin to the tube.
6. The method of claim 1, wherein the metal tube has a bottom and wherein the tray has a bottom and wherein the step of placing the thermally-conductive metal tube into the tray includes placing the bottom of the metal tube in thermal contact with the bottom of the tray.
7. The method of claim 2, further including the step of serving a food product from said food service counter.
8. The method of claim 1, wherein the dispenser is a condiment dispenser and wherein placing a condiment dispenser into the upright, thermally-conductive metal tube passively refrigerates the contents of the condiment dispenser.
9. The method of claim 2, wherein the food service counter has a top surface, wherein the method further includes the step of providing an insulation layer to a portion of the metal tube above the top surface of the food service counter.
10. A method of controlling the temperature of a vessel stored in a temperature-controlled tray having a first height, the vessel having a second height greater than the first height, said method comprising the steps of:
- placing a thermally-conductive metal tube into the temperature-controlled tray, the metal tube having a height greater than the first height but less than the second height, the metal tube also having an interior cross sectional shape;
- providing a thermally insulating collar to a portion of the tube, the thermally insulating collar covering at least part of the temperature-controlled tray and insulating portions of the tube.
11. The method of claim 10, further including the step of:
- placing a dispenser having an exterior shape into the upright thermally-conductive metal tube;
- wherein the interior cross sectional shape of the metal tube conforms to and is larger than the exterior shape of the condiment dispenser.
12. The method of claim 10, including the step of providing the temperature-controlled tray to a food service counter.
13. The method of claim 10 including the step of providing a thermally-conductive fin to the metal tube.
14. The method of claim 10, wherein the temperature-controlled tray has a bottom and wherein the step of placing the thermally-conductive metal tube into the temperature-controlled tray includes the step of placing the thermally-conductive tube such that it makes thermal contact with the bottom of the tray.
15. The method of claim 11, further including the step of serving a food product from said food service counter.
16. The method of claim 11, wherein placing a dispenser into the upright, thermally-conductive metal tube passively refrigerates the contents of the dispenser.
17. The method of claim 11, wherein the food service counter has a top surface, wherein the method further includes the step of providing an insulation layer to a portion of the metal tube above the top surface of the food service counter.
Type: Application
Filed: May 23, 2012
Publication Date: Oct 4, 2012
Applicant: PRINCE CASTLE INC. (CAROL STREAM, IL)
Inventors: KOREY V. KOHL (ROGERS, MN), ROBERT A. IVERSON (MOUND, MN), LOREN VELTROP (CHICAGO, IL), CHRISTOPHER B. LYONS (LAGRANGE PARK, IL), DONALD VAN ERDEN (WILDWOOD, IL)
Application Number: 13/478,637
International Classification: A23L 1/221 (20060101); A23L 1/025 (20060101);