AU604968B2 - Self-contained cooling apparatus - Google Patents

Description

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INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 4: (11) International Publication Number: WO 89/ 00271 17/08 Al (43) International Publication Date: 12 January 1989 (12.01.89) (21) International Applicalion Number: PCT/US88/02258 4810 Park Newport, Apartment 217, Newport Beach, CA 92660 (US).

(22) I .ernational Filing Date: 5 July 1988 (05,07,88) (74) Agents: SIMPSON, Andrew, H. et al.; Knobbe, Mart- (31) Priority Application Numbers: 070,973 ens, Olson and Bear, 620 Newport Center Drive, 16th 169,869 Floor, Newport Beach, CA 92660 (US), 208,371 (81) Designated States: AT (European patent), AU, BE (Eu- (32) Priority Dates: 7 July 1987 (07,07.87) ropean patent), BR, CH (European patent), DE (Eu- 17 March 1988 (17.03.88) ropean patent), FR (European patent), GB (Euro- 22 June 1988 (22.06.88) pee.n patent), IT (European patent), JP, LU (European patent), NL (European patent), SE (European (33) Priority Country; US patent).

(71) Applicant: INTERNATIONAL THERMAL PACK- Published AGING, INC, [US/US]; 1100 Glendon Avenue, Suite With international search report.

2050, Los Angeles, CA 90024 Before the expiration of the time limit for amending the claims and to be republished in the event of the receipt (72) Inventors: STEIDL, Gary 1730 S. El Camino Real, of amendments.

Apartment H-208, Encinitas, CA 92024 TIO- B..JP, 23 MAR 1989 MAS, Dennis, A. 20131 Allentown Drive, Los Angeles, CA 91364 SABIN, Cullen, Ml. ;516 Glen- A A crest Drive, Solana Beach, CA 92075 COVER, AUSRALIAN John, H, 3 0 JAN1989 PATENT OFFICE (54) T!~e SELF CONTAINED COOLING APPARATUS This document contains the ameridments made under Sectfon 49 and is correct for print ig" (57) Abstract Disclosed is a self-contained, rapid cooling device that can be stored for indefinite periods without losing its cooling potential. A liquid in a first chamber (12) undergoes a chamber of phase into vapor which cools the first chamber A sorbent in a second chamber (20) Is in fluid communication with the vapor and removes the vapor from the first chamber The cooling process is facilitated by providing'the interior surface of the first chamber with a wicking material (16) to retain the largest possible contact between the liquid and the first chamber (12) as the level of the liquid lowers during the vaporization process. A phase separator (34) and a porous space-filling wick prevent unvaporized liquid from passing into the second chamber :.e WO 89/00271 PCT/US88/02258 SELF CONTAINED COOLING APPARATUS Background of the Invention The invention relates to temperature changing devices and, in particular, to portable or disposable food or beverage coolers.

There are many foods and beverages that may be stored almost indefinitely at average ambient temperature of 20'-25"C but that should be cooled immediately before consumption. In general, the cooling of these foods and beverages is accomplished by electrically-run refrigeration units. The use of these units to cool such foods and beverages is not always practical because refrigerators generally require a source of electricity, they are not usually portable, and they do not cool the food or beverage quickly.

An alternate Method for providing a cooled material on demand is to use portable insulated containers. However, these containers function merely to maintain the previous temperature of the food or beverage placed inside them, or they require the use of ice cubes to provide the desired cooling effect. When used in conjunction with ice, insulated containers are much more bulky and heavy than the food or beverage. Moreover, in many locations, ice may not be readily available when the cooling action is required.

Ice cubes have also been used independently to cool food or beverages rapidly. However, utilization of ice independently for cooling is often undesirable because ice may be stored only for limited periods above 0C.

Moreover, ice may not be availabe when the cooling action is desired.

In addition to food and beverage cooling, there are a number of other applications for which a portable cooling device is extremely desirable These include medical applications, including cooling of tissues or organs; preparatioh of cold compresses and cryogenic destruction of WO 89/00271 PCT/US88/02258 2 tissues as part of surgical procedures; industrial applications, including production of cold water or other liquids upon demand; preservation of biological specimens; cooling of protective clothing; and cosmetic applications.

A portable cooling apparatus could have widespread utility in all these areas.

Most attempts to build a self-contained miniaturized cooling device have depended on the use of a refrigerant liquid stored at a pressure above atmospheric pressure, so that the refrigerant vapor could be released directly to the atmosphere. Unfortunately, many available refrigerant liquids for such a system are either flammable, toxic, harmful to the environment, or exist in liquid form at such high pressures that they represent an explosion hazaed in quantities suitable for the intended purpose. Conversely, other available refrigerant liquids acceptable for discharge into the atmosphere (such as carbon dioxide) have relatively low heat capacities and latent heats of vaporization. As a result, some cooling devices which release carbon dioxide are more bulky than is commercially acceptable for a portable device.

An alternate procedure for providing a cooling effect in a portable device is to absorb or adsorb the refrigerant vapor in a chamber separate from the chamber in which the evaporation takes place. In such a system, the refrigerant liquid boils under reduced pressure in a sealed chamber and absorbs heat from its surroundings. The vapor generated from the boiling liquid is continuously removed from the first chamber and discharged into a second chamber containing a desiccant nr sorbent that absorbs the vapor.

The use of two chambers to produce a cooling effact around one chamber is illustrated in U.S. Patent No.

4,250,720 to Siegel and Great Britain Patent No. 2,095 ,386 to Cleghorn, et al. These patents disclose a two-chamber 35 apparatus connected by a tube. The Siegel patent uses water as the refrigerant liquid, while the Cleghorn, et al.

r l~in;i R~iylsl ~i i -II~ tm m i r+'i ll r .i log% :o:1 0 s O00O O0 so S0 0 o 0OgB 3 patent is not limited to water. The Siegel patent envisions the use of such a cooling device to cool food or beverages.

However, in both the Siegel and Cleghorn, et al.

patents, the rapid initial coo].ing effect gradually slows as a result of the both decrease in temperature of the object, to be. cooled and decrease in the heat transfer Orea of the first chamber. The decrease in heat transfer afe a due to the fact that the portion of the f irst chamber in contact with the liquid decreases as the liquid vaporizes and the liquid level drops. Moreover, in these systems, the evaporation process is limited by the surface area from which the liquid can boil. In addition, the systems do not effectively moinimize the amount oi liquid which is entrained in the vapor phase caused by uncontrolled boiling of the evaporating liquid.

Accordingly, n~ne preferred objective of the present invention is to provide a self-contained sorption cooling device with a means to alleviate the decrease in heat 20 transfer as the liquid vaporizes and therefore speed the cooling process.

A preferred object of the present invention is to accelerate the vaporation process by increasing the surface area from which the liquid can evaporate. As a result, the cooling process will be accelerated as well.

Another preferred object of the present invention is to control the evaporation' process by limiting liquid entrainment in the vapor phase.

Summary of the Invent, ion 30 According to a first aspect of the present invention there is provided a self-contained cooling apparatus, comprising: a first chamber containing a liquid wherein said first chamber has an interior surface provided with a wicking material for said liquid, said wicking material holding said liquid against said iriderior ~surface both before and during the operation of said us

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90084tgtO24.1e ky22544,letl 3A device; a second evacuated chamber containing a sorbent for said liquid; a conduit connecting said first and second chambers; a valve in said conduit for preventing flow through said conduit between said chambers; and an actuator for opening said valve to connect said first and second chambers, permitting said liquid to vaporize out of said wicking material and permitting said vapor to pass through said conduit and into said sorbent, whereby the evaporation of said liquid serves to cool said first chamber immediately upon opening said valve.

According to a second aspect of the present invention there is provided a method for cooling, comprising the steps of: providing a cooling device, comprising: a first chamber containing a liquid wherein said first chamber has an interior surface provided with a wicking material for said liquid, said wicking material holding said •liquid against said interior surface both before and during the operation of said device; (ii) a second evacuated chamber containing a sorbent for said liquid; g* (iii) a conduit connecting said first and said second chambers; 3 (iv) a valve in the conduit preventing communication between said first chamber and said second chamber while said valve is closed; and means for opening said valve to 35 connect said first and said second RA, chambers; t opening said valve to permit communication L 90S m 4,l22 900802,tgcO24.etky22544.ie,2 L_ 1

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4 4 4 between said first chamber and said second chamber, whereby the pressure in said first chamber is reduced, causing said liquid to boil, forming a vapor, which vap'-' is directed through said conduit into said seoond chamber; and removing vapor fl ,m said second chamber by collecting same i said sorbent untll an equilibrium condit ,on is x'eached, wherein said sorbent is substantially saturated or substantially all of the liquid originally in said first chamber has been collected in said sorbent.

In a preferred embodiment, the liquid is water. It is preferred that the wicking material which lines the interior surface of the first chamber consists of a highly hydrophilic material, such as gel-forming polymers and water-wicking polymers capablo of coating the 006.

interior of the first chamber, 20 In one embodiment of the invention, the liquid is mixed with a nucleating agent that promotes ebullition of the liquid. A phase separator for preventing unvaporized liquid from the first chamber from passing through the conduit into the second chamber may acvantageously be included in the device. The sorbent material may be an adsorbent or absorbent, and the second chamber preferably contains sufficient sorbent to absorb or adsorb substantially all of the liquid in the first chamber.

Tdpd The entire device is preferably disposable.

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WO 89/06271 PCT/US88/02258 In use, the vaporization process causes the level of the liquid in the first chamber to drop, but, in the preferred embodiment, the wicking material retains the liquid on the interior surface of the first chamber. This maintains a substantial area of contact between the liquid and the interior surface of the first chamber to avoid a reduction in the effective heat transfer area of the first chamber and a resultant slowing of the cooling process.

The present invention provides a self-contained rapid cooling device that cools a food, beverage, or other material or article from ambient temperature on demand in a timely manner, exhibits a useful change in temperature, retains the heat produced from the cooling process or retards the transfer of heat from the sorbent back to the material beiig cooled, can be stored for unlimited periods without losing its cooling potential, and is able to meet government standards for safety in human use.

Brief escription of the Drawing The figure is a schematic representation of a cooling device according tolthe present invention.

Detailed Description of the Invention In Figure 1, the cooling device 10 has a first chamber 12 lined on the interior surface 14 with a wicking material 16, which, in a preferred embodiment, could be accomplished by flocking or spraying the interior surface 14 with the wicking material 16, and the first chamber 12 is filled with a refrigerant liquid 18. The cooling device 10 also includes a second Chamber 20 surrounded by a thermal insulator 22 which is at -least partially filled with a sorbent 24. The second chamber may also advantageously be -evacuated to the extent that it contains only the vapor of the refrigerant liquid.

Connecting the first and second chambers 12 and 20 is a conduit 28 and a valve 30 interposed in the conduit 28, allowing fluid communication between the chambers 12 and through 'he conduit 28 only when the valve 30 is open.

L S Ii O WO 89/00271 PCT/US88/02258 6 The operation of the cooling device 10 is suspended the system is static and no cooling occurs) until the valve 30 is opened, at which time the conduit 28 provides fluid communication between the first and second chambers 12 and 20. Opening the valve 30 between the first and second chambers 10 and 20 causes a drop in pressure in chamber 12 because the second chamber 20 is evacuated. The drop in pressure in the first chamber 12 upon opening of the valvk 30 causes the liquid 18 to boil at ambient temperature into a liquid-vapor mixture 32. This liquidto-gas phase change can occur only if the liquid 18 removes heat equal to the latent heat of vaporization of the evaporated liquid 18 from the first chamber 12. This causes the first chamber 12 to cool. The cooled first chamber 2, in turn, removes heat from its surrounding material/as indicated by the arrows 33.

The liquid-vapor mixture 32 is directed through a liquid-vapor collector and separator 34 of conventional design, which separates the liquid 18 from the vapor, allowing the separated liquid 18 to reourn to the first chamber 12 through the liquid return line 38 and allowing the vapor to pass through the conduit 28 into the second chamber 20. Once inside the second chamber 20, the vapor is absorbed or ads'rbed by the sorbent 24. This facilitates the maintenance of a reduced vapor pressure in the first chamber 12 and allows more of the liquid 18 to boil and become vapor, further reducing the temperature of chamber 12. The continuous removal of the vapor maintains the pressure in the first chamber 12 below the vapor 30 pressure of the liquid 18, so that the liquid 18 boils and produces vapor continuously until sorbent 24 is saturated, until the liquid 18 has boiled away or until the temperature of the liquid 18 has dropped below its boiling point.

During the vaporization process, the level of the liquid 18 in the first chamber 12 drops. The kicking j( it ~rrr* ;IWO 89/00271 PCT/US88/02258 7 material 16 retains the liquid 18 on the interior surface 14 of the first chamber 12 to prevent a reduction in the area of contact between the liquid 18 and the interior surface 14 which would cause a reduction in the effective heat transfer surface area of the first chamber 12 and would thus slow the cooling process.

Three important components of the present invention are the evaporating liquid, the sorbent, and the wicking material. The liquid and the sorbent must be complimentary the sorbent must be capable of absorbing or adsorbing the vapor produced by the liquid), and suitable choices for all three of these components would be any combination able to make a useful change in temperature in a short time, meet government standards for safety, and be compact.

The refrigerant liquids used in the present invention preferably have a high vapor pressure at ambient temperature, so that a reduction of pressure will produce a high vapor production rate. The vapor pressure of the liquid at 20*C is preferably at least about 9 mm Hg, and more preferably is at least about 15 or 20 mm Hg.

Moreover, for some applications (such as cooling of food products), the liquid should conform to applicable government standards in case any discharge into the surroundings, accidental or otherwise, occurs. Liquids with suitable characteristics for various uses of the invention include: various alcohols, such as methyl alcohol and ethyl alcohol; ketones or aldehydes, such as acetone and acetaldehyde; water; and freons, such as freon 30 C318, 114, 21, 11, 114B2, 113 and 112. The preferred liquid is water.

In addition, the refrigerant liquid may be mixed with an effective quantity of a miscible nucleating agent having a greater vapor pressure than the liquid to promote ebullition so that the liquid evaporates even more quickly and; smoothly, and so that supercooling of the liquid does

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1 pp c WO 89/Q0271 PCT/US88/02258 not occur. Suitable nucleating agents include ethyl alcohol, acetone, methyl alcohol, propyl alcohol and isobutyl alcohol, all of which are miscible with water.

For example, a combination of a nucleating agent with a compatible liquid might be a combination of 5% ethyl alcohol in water or 5% acetone in methyl alcohol. The nucleating agent preferably has a vapor pressure at 25*C of at least about 25 mm Hg and, more preferably, at least about 35 mm Hg. Alternatively, solid nucleating agents may be used, such as the conventional boiling stones used in chemical laboratory applications.

The sorbent material used in the second chamber 20 is preferably capable of absorbing and adsorbing all the vapo produced by the liquid, and alsc preferably will meet government safety standards for use in an environment where contact with food may occur. Suitable sorbents for various applications may include barium oxide, magnesium perchlorate, calcium sulfate, calcium oxide, activated carbon, calcium chloride, glycerine, silica gel, alumina gel, calcium hydride, phosphoric anhydride, phosphoric acid, potassium hydroxide, sulphuric acid, lithium chloride, ethylene glycol and sodium sulfate.

In selecting the wicking material 16, any of a number of materials may be chosen, depending upon the requirements of the system and the particular refrigerant liquid 18 being used. The wicking material may be something as simple as cloth or fabric having an affinity for the refrigerant liquid 18 and a substantial wicking ability.

Thus, for example, when the refrigerant liquid is water, the wicking material may be cloth, sheets, felt or flocking material which may be comprised of cotton, filter material, natural cellulose, regenerated cellulose, cellulose derivatives, blotting paper or any other suitable material.

The most preferred wicking material would be highly hydrophilic, such as gel-forming polymers which would be capable of coating the interior surface of the evaporation

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'kc ul i WC--89/00271 PCT/US88/02258 9 chamber. Such materials preferably consists of alkyl, aryl and amino derivative polymers of vinylchloride acetate, vinylidene chloride, tetrafluoroe'hylene, methyl methacrylate, hexanedoic acid, propenoic acid, 1, 3-isobenzofurandione, 1 h-pyrrole-2,5-dione or hexahydro-2 h-azepin-2-one.

The wicking material may be sprayed, flocked, or otherwise coated or applied onto the interior surface of the first chamber. In a preferred embodiment, the wicking material is electrostatically deposited onto that surface.

In another embodiment, ths wicking material is mixed with a suitable solvent, s, ;h as a non-aqueous solvent, and then the solution is applied to the interior surface of the first chamber.

In another preferred embodiment, the wickiL. material is able to control any violent boiling of the evaporator and thus reduce any liquid entrainment in the vapor phase.

In such an embodiment, the wicking material is a polymer forming a porous space-filling or sponge-like structure, and it may fill all or part of the first chamber.

The thermal insulator 22 may be any conventidnal insulation material, but is preferably an inexpensive, easily-formed material such as a low-cost polystyrene foam.

The valve may be selected from any of the various types shown in the prior art.

The invention also includes a method of using the cooling device described herein. This method includes the step of providing a cooling device of the type set forth herein; opening the valve between the first chamber 12 and the second chamber 20, whereby the pressure in the first chamber is reduced, causing the liquid to boil, forming a vapor, which vapor is collected by the sorbent material; and removing vapor from the second chamber by collecting the same in the sorbent until an equilibrium condition is reached wherein the sorbent is substantially saturated or substantially all of the liquid originally in the first im- WO 89/00271 PCT/US88/02258 chamber has been collected in the sorbent. The process is preferably a one-shot process; thus, openinac of the valve in the conduit 28 connecting the first 4amber 12 and the second chamber 20 is preferably irreversible. At the same time, the system is a closed system; in other words, the refrigerant liquid does not escape the system, and there is no means whereby the refrigerant liquid or the sorbent nay escape either the first chamber 12 or the second chamber

Claims (20)

1. A self-contained cooling apparatus, comprising: a first chamber containing a liquid wherein said first chamber has an interior surface provided with a wicking material for said liquid, said wicking material holding said liquid against said interior surface both before and during the operation of said device; a second evacuated chamber containing a sorbent for said liquid; a conduit connecting said first and second chambers; a valve in said conduit for preventing flow through said conduit between said chambers; and an actuator for opening said valve to connect said first and second chambers, permitting said liquid to vaporize out of said wicking matea:rial and permitting said vapor to through said conduit and into :ad said sorbent, whereby the evaporation of said liquid serves to cool said first chamber immediatel y upon 20 opening said valve.

2. An apparatus according to Claim 1, wherein said t wicking material for said liquid comprises a :hydrophilic gel-forming polymer.

3. An apparatus according to Claim 1, wherein said wicking material for said liquid consists of alkyl, aryl and amino derivative polymers selected from the group comprising vixylchloride acetate, vinylidene chloride, tetrafluoroethylene, methyl methacrylate, hexanedoic acid, dihydro-2,5-furandione, propenoic 30 acid, 1,3-isobenzofurandione, 1 and hexahydro-2 h-azepin-2-one.

4. An apparatus according to Claim 1, wherein said wicking material forms a porous space-filling structure. eee** 35 5. An apparatus according to Claim 4, wherein said porous structure substantially fills said first ichamber. LS 9O803,tgcO24.1eIty22544.1et4 1 I -12-

6. An apparatus according to Claim 1, wherein said wicking material lines the interior surface of said first chamber. 1. An apparatus according to Claim 6, wherein said wicking material has been electrostatically applied to the interior surface of said first chamber.

8. An apparatus according to Claim 1, wherein said wickinq material, for said liquid consists of cotton, natural cellulose, regenerated cellulose, or cellulose derivatives.

9. An apparatus according to Claim 1, wherein said liquid has a vapor pressure at 20 0 C of above 9mm Hg. An apparatus according to Claim 1, wherein said liquid is water.

11. An apparatus according to Claim 1, further comprising a nucleating material having a vapor pressure at 25 0 C of above 25 mm Hg in said first chamber to facilitate boiling of said liquid when the pressure in said first chamber drops as a result 20 of opening said valve. 0*e4 1* 12. An apparatus according to Claim 11, wherein said nucleating material is ethyl alcohol, acetone, methyl alcohol, propyl alcohol or isobutyl alcohol.

13. An apparatus according to Claim 1, wherein said second chamber is in contact with a thermal insulator.

14. A method for cooling, comprising the steps of: providing a cooling device, comprising; i) a first chamber containing a liquid wherein said first chamber has an S Ol interior surface provided with a wicking material for said liquid, said wicking material holding said liquid against said interior surface 35 both before and during the operation of said device, (ii) a second evacuated chamber containing L S t O 82,tgcO24,l1te y22544.1e, 121 L. i U ~l :i "l'(;riil; i X;1 rrr3^~li-i I k wg00 V, *e 0*0* C soe 0 0* 6 eq 5 "13 a sorbent for said liquid; (iii) a conduit connecting said first and said second chambers; (iv) a valve in the conduit preventing communication between said first chamber and said second chamber while said valve is closed, and means for opening said valve to connect said first and -aid second chambers; opening said valve to permit communication between said first chamber and said second chamber, whereby the pressure in said first chamber is reduced, causing said liquid to boil, forming a vapor, which vapor is directed through said conduit into said second chamber; and removing vapor from said second chamber by collecting same in said sorbent until an 20 equilibrium condition is reached, wherein said sorbent is substantially saturated or substantially all of the liquid originally in sacd first chamber has been collected in said sorbent.

15. A method according to Claim 14, wherein said wicking material for said liquid is a hydrophilic gel- forming polymer.

16. A method according to Claim 14, wherein said wicking material for said liquid consists of alkyl, aryl and 30 amino derivative polymers selected from the group comprising vinylchloride acetate, vinylidene chloride, tetrafluoroethylene, methyl methacrylate, hexanedoic acid, dihydro-2,5-furandione, propenoic acid, 1,3-isobenzofurandione, 1 35 and hexahydro-2 h-azepin-2-one.

17. A method according to Claim 14, wherein said wicking material forms a porous space-filling structure. 802,4tgcO24,et.ky22544je t1 01 0 V "ii -14-

18. A method according to Claim 17, wherein said porous structure substantially fills seid first chamber.

19. A method according to Claim 14, wherein said wicking material lines the interior surfaces of said first chamber. A method according to Claim 19, wherein said wicking material has been electrostatically applied to the interior surface.

21. A method according to Claim 14, wherein said wicking material consists of cotton, natural cellulose, regenerated cellulose, or cellulose derivatives.

22. A method according to Claim 14, wherein said liquid has a vapor pressure at 20 0 C of above 9 mm Hg.

23. A method according to Claim 14, wherein said liquid is water.

24. A self-contained cooling apparatus substantially as hereinbefore described with reference to the accompanying drawing. 00

25. A method for cooling substantially as hereinbefore o* 20 described with reference to the accompanyipg drawing. *o Dated this 2nd day of August, 1990 INTERNATIONAL THERMAL PACKAGING By its Patent Attorneys DAVIES COLLISON *6* 1 I S Sees 0 083,tgcO24.et4kyN4jet14