Isothermal cooling method and device

• US 4,986,076 A
• Filed: 08/28/1989
• Issued: 01/22/1991
• Est. Priority Date: 06/07/1989
• Status: Expired due to Fees

• Current Assignee: Kenneth Kirk
• Original Assignee: Kenneth Kirk
• Inventors: Habicher, Berthold H., Kirk, Kenneth, Remick, Cassius D., Burns, Charles M.
• Primary Examiner(s): King, Lloyd L.
• Application Number:
  US07/398,936
• Time in Patent Office: 512 Days
• Field of Search: 62/4, 62/294, 62/480, 62/530, 206/219
• US Class Current: 62/4
• CPC Class Codes: A61F 2007/0276 with separate compartments connectable by rupturing a wall or membrane
• CPC Class Codes: A61F 2007/0292 using latent heat produced or absorbed during phase change of materials, e.g. of super-cooled solutions
• CPC Class Codes: A61F 7/106 self-cooling, e.g. using a chemical reaction
• CPC Class Codes: C09K 5/16 Materials undergoing chemical reactions when used
• CPC Class Codes: F24V 30/00 Apparatus or devices using heat produced by exothermal chemical reactions other than combustion
• CPC Class Codes: F25D 5/00 Devices using endothermic chemical reactions, e.g. using frigorific mixtures

Abstract

One version of the invention provides a method for cooling and maintaining an object at a substantially constant temperature. The method includes adding a salt that dissolves endothermically in water to a mixture containing at least water, a surfactant and an emulsified thermal buffer. The "salt:water:thermal buffer" ratio is such that the reaction provides sufficient endotherm to cool the system to the freezing point of the thermal buffer and effect at least a partial phase change of the thermal buffer. Another version of the invention provides a device for effecting the method. The device has a reaction compartment consisting of two portions separated by a frangible barrier, one portion containing the emulsified thermal buffer in water and the other portion the salt that dissolves endothermically into solution. One specific version of the device is a container for transporting an amputated extremity such as a severed finger to another location for replantation.

Claims

1. A method for cooling and maintaining an object at a constant temperature, comprising:

adding a salt that dissolves endothermically in water to a mixture containing at least water, a surfactant and an emulsified thermal buffer until a temperature near the freezing point of the thermal buffer has been reached and at least a partial phase change of the thermal buffer has occurred; and

bringing the resulting mixture into direct or indirect contact with the object.

2. A method as recited in claim 1 wherein the salt is selected from the group consisting of potassium thiocyanate, ammonium nitrate or ammonium thiocyanate.

3. A method as recited in claim 1 wherein the salt is potassium thiocyanate and the mixture contains water, octylphenol ethoxylate as the surfactant and emulsified cyclohexane as the thermal buffer.

4. A method as recited in claim 1 wherein a plurality of salts are dissolved endothermically into solution.

5. A method as recited in claim 4 wherein the endotherm of the plurality of salts per gram of water is higher than the endotherm of any single salt per gram of water.

6. A method as recited in claim 4 wherein the salts are selected from the group consisting of KSCN, NH₄ NO₃, NH₄ SCN and Na₂ CO₃.10H₂ O.

7. A method as recited in claim 6 wherein one of the salts is Na₂ CO₃.10H₂ O.

8. A device for cooling and maintaining an object at a constant temperature comprising

a thermal buffer compartment containing at least a surfactant, an emulsified thermal buffer and water;

and

a reaction compartment having two portions separated by a frangible barrier, the first portion containing a first reactant and the second portion a second reactant, said first and second reactants reacting endothermically upon contact.

9. A device as recited in claim 8 wherein the first portion of the reaction compartment contains water and the second portion contains a salt that dissolves endothermically into solution.

10. A device for cooling and maintaining an object at constant temperature comprising at least one reaction compartment having two portions separated by a frangible barrier, the first portion containing at least a surfactant, a emulsified thermal buffer and water and the second portion at least one salt that dissolves endothermically into solution.

11. A device as recited in claim 10 further comprising an insulating outer shell.

12. A device as recited in claim 10 wherein the reaction compartment contains a plurality of salts that dissolve endothermically into aqueous solution.

13. A device as recited in claim 10 wherein the reaction compartment is a cooling bag, the surfactant is octylphenol ethoxylate, the thermal buffer is cyclohexane and the salt is potassium thiocyanate.