Liquid heating method and apparatus particularly useful for vaporizing a liquid condensate from cooling devices

• US 20030206730A1
• Filed: 02/07/2003
• Published: 11/06/2003
• Est. Priority Date: 08/22/2000
• Status: Active Grant

• Current Assignee: ATCT Advanced Thermal Chips Technologies Limited
• Original Assignee: ATCT Advanced Thermal Chips Technologies Limited
• Inventors: Golan, Gady
• Granted Patent: US 6,965,732 B2
• Time in Patent Office: Days
• US Class Current: 392/399
• CPC Class Codes: A47J 27/04 for cooking food in steam; Devices for extracting fruit juice by means of steam ; Vacuum cooking vessels steam-heated vessels for hotels, restaurants or canteens A47J27/16
• CPC Class Codes: A47J 27/16 heated by steam
• CPC Class Codes: A47J 31/54 Water boiling vessels in beverage making machines
• CPC Class Codes: F22B 1/287 with water in sprays or in films
• CPC Class Codes: F24F 13/222 for evacuating condensate
• CPC Class Codes: F24F 5/0042 characterised by the application of thermo-electric units or the Peltier effect
• CPC Class Codes: F25D 21/14 Collecting or removing condensed and defrost water; Drip trays
• CPC Class Codes: H05B 2203/02 Heaters using heating elements having a positive temperature coefficient
• CPC Class Codes: H05B 3/24 heating conductor being self-supporting
• CPC Class Codes: H05B 3/50 heating conductor arranged in metal tubes, the radiating surface having heat-conducting fins

Abstract

A method and heating device for heating a liquid, particularly useful for removing liquid condensate from cooling devices, by wetting a heating plate with the liquid and controlling the electrical power supply to maintain the heating plate at a the predetermined temperature above the boiling point of the liquid, such that when the heating plate is not wetted by the liquid, the electrical power supply to the heating plate is automatically maintained at a relatively low value, but as soon as the heating plate is wetted by the liquid, the electrical power supplied to the heating plate is automatically increased until the liquid is completely evaporated. The heating plate is heated by one or more PTC thermistors in which the electrical resistance increases with temperature to automatically maintain the predetermined temperature. Besides evaporating liquid condensate, the heating device is described for use in many other applications including steam generation, space heating and plastic molding.

Claims

1. A method of heating a liquid, comprising:

electrically heating a heating plate, via an electrical power supply, to a predetermined temperature above the boiling point of the liquid to be heated;

wetting the heating plate with the liquid to be heated;

and controlling said electrical power supply to maintain said heating plate at said predetermined temperature, such that when the heating plate is not wetted by said liquid, the electrical power supplied to the heating plate is automatically maintained at a relatively low value;

but as soon as the heating plate is wetted by said liquid, the electrical power supplied to the heating plate is automatically increased to a relatively high value by the load produced by the wetting liquid, and is automatically controlled thereafter in response to said load to maintain said heating plate at said predetermined temperature, unless and until the liquid is completely evaporated, whereupon the electrical power supplied to the heating plate is automatically reduced to, and maintained at, said relatively low value until the heating plate is again wetted by the liquid to be heated.

2. The method according to claim 1, wherein said heating plate is heated by a positive temperature coefficient heating device in which the electrical resistance increases with an increase in current such as to effect self-regulation with respect to temperature.

3. The method according to claim 2, wherein said positive temperature coefficient heating device includes at least one thermistor.

4. The method according to claim 3, wherein said liquid to be heated is a water condensate of an electrically-operated cooling device to be evaporated.

5. The method according to claim 1, wherein said liquid is water to be heated or vaporized in an electrical appliance.

6. The method according to claim 1, wherein said liquid is water to be vaporized in a steam generator.

7. A method of removing a liquid condensate from a cooling device, comprising:

electrically heating a heating plate, via an electrical power supply, to a predetermined temperature above the boiling point of the liquid condensate;

conducting the liquid condensate to the heating plate to wet the heating plate;

and controlling said electrical power supply to maintain said heating plate at said predetermined temperature, such that when the heating plate is not wetted by said liquid, the electrical power supply to the heating plate is automatically maintained at a relatively low value;

but as soon as the heating plate is wetted by said liquid, the electrical power supplied to the heating plate is automatically increased to a relatively high value by the load produced by the wetting liquid, until the liquid is completely evaporated, whereupon the electrical power supplied to the heating plate is automatically reduced to, and maintained at, said relatively low value until the heating plate is again wetted by the liquid condensate.

8. The method according to claim 7, wherein said heating plate is heated by a positive temperature coefficient heating device in which the electrical resistance increases with an increase in current such as to effect self-regulation with respect to temperature.

9. The method according to claim 8, wherein said positive temperature coefficient heating device includes at least one thermistor.

10. Apparatus for heating a liquid, comprising:

a heating plate adapted to be wetted by the liquid to be vaporized;

a heater device for heating said heating-plate;

and an electrical power supply for energizing said heater device;

said electrical power supply being automatically controlled to maintain said heating plate at a predetermined temperature above the boiling point of the liquid to be heated such that when the heating plate is not wetted by said liquid, the electrical power supply to the heating plate is automatically maintained at a relatively low value;

but as soon as the heating plate is wetted by said liquid, the electrical power supplied to the heating plate is automatically increased to a relatively high value by the load produced by the wetting liquid, and is automatically controlled thereafter in response to said load to maintain said heating plate at said predetermined temperate, unless and until the liquid is completely evaporated, whereupon the electrical power supplied to the heating plate is automatically reduced to, and maintained at, said relatively low value until the heating plate is again wetted by the liquid to be heated.

11. The apparatus according to claim 10, wherein said heating plate is heated by a positive temperature coefficient (PTC) heating device in which the electrical resistance increases with an increase in current such as to effect self-regulation with respect to temperature.

12. The apparatus according to claim 11, wherein said PTC heating device includes a frame of electrically-insulating material, at least one PTC thermistor secured within said frame, and a pair of electrodes attached to the opposite faces of the frame and having substantially planar faces in contact with said PTC thermistor therein.

13. The apparatus according to claim 12, wherein said frame is constructed to receive a plurality of said PTC thermistors in side-by-side relation, with the opposite faces of the thermistors substantially flush with each other so as to be contacted by said substantially planar faces of the pair of electrodes.

14. The apparatus according to claim 12, wherein said frame is of electrically-insulating, thermally-conductive ceramic material.

15. The apparatus according to claim 12, wherein each of said electrodes includes a substantially planar plate integrally formed with a terminal projecting from one side thereof.

16. An electrical heating device comprising a heating unit including:

a metal plate;

a pair of flat PTC thermistors located on one face of the metal plate;

an electrical connector located on said one face of the metal plate between said PTC thermistors and electrically connected thereto;

and a pair of U-shaped clamps overlying said PTC thermistors and engaging the opposite face of the radiator plate to fix the PTC thermistors thereto.

17. The electrical heating device according to claim 16, wherein said heating unit is putted within a thermally-conductive, electrically-insulating putting material.

18. The electrical heating device according to claim 16, wherein said heating unit is secured to one side of a fluid conduit for heating a fluid flowing therethrough.

19. The electrical heating device according to claim 16, wherein said heating unit is secured to each of the opposite sides of a fluid conduit for heating a fluid flowing therethrough.

20. The electrical heating device according to claim 16, wherein said heating unit is secured to the bottom of a cooking receptacle for cooking food therein.

21. The electrical heating device according to claim 20, wherein said cooking receptacle is a receptacle for cooking food therein by steam heating.

22. The electrical heating device according to claim 16, wherein said heating unit is secured to the bottom of a radiation panel having a fluid conduit including an upwardly extending section and a downwardly extending section;

said heating unit having a cold liquid inlet connected to the bottom of said downwardly-extending section of the conduit, and a hot fluid outlet connected to the bottom of said upwardly extending section.

23. The electrical heating device according to claim 16, wherein said heating unit is attached to a plastic mold for heating plastic material within the mold.

24. The electrical heating device according to claim 16, wherein said heating unit is included as in a coffee machine for heating water as it is dispensed by said coffee machine.

25. The electrical heating device according to claim 16, wherein said heating unit is included in a coffee pot for heating water within the coffee pot.

26. The electrical heating device according to claim 16, wherein said heating unit is in a steam iron for generating steam discharged from said steam iron.