Pulse electrothermal and heat-storage ice detachment apparatus and methods

• US 20060272340A1
• Filed: 01/24/2006
• Published: 12/07/2006
• Est. Priority Date: 02/11/2002
• Status: Active Grant

• Current Assignee: The Trustees of Dartmounth College (Dartmouth College)
• Original Assignee: The Trustees of Dartmounth College (Dartmouth College)
• Inventors: Petrenko, Victor
• Granted Patent: US 7,638,735 B2
• Time in Patent Office: Days
• US Class Current: 62/73
• CPC Class Codes: F25C 1/12 by freezing water on cooled surfaces, e.g. to form slabs
• CPC Class Codes: F25C 5/08 by heating bodies in contact with the ice
• CPC Class Codes: F25D 21/08 by electric heating
• CPC Class Codes: F28F 17/00 Removing ice or water from heat-exchange apparatus
• CPC Class Codes: Y02P 60/85 Food storage or conservation, e.g. cooling or drying

Abstract

Systems and methods for pulse electrothermal and heat-storage ice detachment. A pulse electrothermal ice detachment apparatus includes one or more coolant tubes, and optionally, fins in thermal contact with the coolant tubes. The tubes and/or fins form a resistive heater. One or more switches may apply electrical power to the resistive heater, generating heat to detach ice from the tubes and/or the fins. A freezer unit forms a heat-storage icemaking system having a compressor and a condenser for dissipating waste heat, and coolant that circulates through the compressor, the condenser and a coolant tube. The coolant tube is in thermal contact with an evaporator plate. A tank, after the compressor and before the condenser, transfers heat from the coolant to a heating liquid. The heating liquid periodically flows through a heating tube in thermal contact with the evaporator plate, detaching ice from the evaporator plate.

Claims

1. Pulse electrothermal ice detachment apparatus, comprising:

one or more coolant tubes of a refrigeration unit;

cooling fins in thermal contact with the coolant tubes, one or both of the tubes or fins forming a resistive heater; and

one or more switches for applying electrical power to the resistive heater, generating heat to detach ice from at least one of the tubes and the fins.

2. Apparatus of claim 1, wherein

the resistive heater comprises a plurality of heater sections,

the one or more switches comprise a plurality of switches, and

the switches are configured to apply the electrical power to the heater sections individually.

3. Apparatus of claim 2, configured such that the electrical power is applied to at least one heater section while coolant continues to flow through coolant tubes of another heater section.

4. Apparatus of claim 1, wherein the tubes and the fins are electrically isolated from one another.

5. Apparatus of claim 4, comprising an insulator formed by at least one of a polymer coating, a thermally conductive adhesive, a metal oxide and a composite-material film, the insulator isolating the tubes and the fins from one another.

6. Apparatus of claim 1, the fins forming a conductive serpentine configuration.

7. Apparatus of claim 1, comprising a power supply for supplying the electrical power.

8. Apparatus of claim 7, the power supply providing a voltage in a range of 0.1V to 1000V.

9. Apparatus of claim 8, the power supply providing a voltage in a range of 6V to 70V.

10. Apparatus of claim 7, the power supply providing an AC voltage having a frequency in a range of 15 Hz to 15 MHz.

11. Pulse electrothermal ice detachment apparatus, comprising:

one or more coolant tubes of a refrigeration unit, the one or more tubes forming a resistive heater; and

one or more switches for applying electrical power to the heater, generating heat to detach ice from the tubes.

12. A method for detaching ice from coolant tubes and/or cooling fins of a refrigeration unit, comprising

accumulating ice on one or both of the coolant tubes and the cooling fins during a normal refrigeration mode, and

applying a pulse of electrical power to one or both of the tubes and the fins to detach the ice.

13. Method of claim 12, further comprising stopping the normal refrigeration mode prior to the applying step.

14. Method of claim 12, further comprising evacuating coolant from the one or more coolant tubes before the step of applying.

15. Method of claim 12, at least one of the one or more coolant tubes and the cooling fins being organized into sections, the step of applying being repeated for each of the sections.

16. Method of claim 15, the sections corresponding to sequential portions of a coolant tube through which coolant flows, the step of applying comprising applying a pulse of electrical power to the sections corresponding to the order in which the coolant flows through the coolant tube.

17. Pulse electrothermal ice detachment apparatus comprising:

an icemaking tube comprising one or more ice growth regions;

one or more of a cold finger and a coolant tube for transferring heat away from each ice growth region;

means for introducing water into the icemaking tube so that at least a portion of the water freezes into ice at the ice growth regions; and

a power supply for periodically supplying a pulse of electrical power to the tube, to melt at least an interfacial layer of the ice to detach the ice from the tube.

18. Apparatus of claim 17, the icemaking tube comprising one or more of a metal, glass, plastic, polymer, Teflon®

, ceramic and carbon fiber.

19. Apparatus of claim 17, comprising one or more heat conduction fins to facilitate heat transfer from the one or more ice growth regions.

20. Apparatus of claim 17, comprising a water supply controlled by a supply valve, and a drain controlled by a drain valve.

21. Apparatus of claim 20, comprising:

a holding tank for holding water from the water supply; and

a pump for pumping the water through the means for introducing.

22. Apparatus of claim 21, comprising a screen for separating surplus water, that drains from the icemaking tube, from the ice.

23. Apparatus of claim 21, comprising a heater to prevent water from freezing in the holding tank.

24. Apparatus of claim 17, comprising apparatus for determining when to harvest the ice by capacitively sensing the ice, by optically sensing the ice, by determining the weight of the ice, by determining an elapsed icemaking time or by determining that water flow is impeded by ice.

25. Pulse electrothermal ice detachment apparatus comprising:

an icemaking tube comprising one or more ice growth regions;

one or more of a cold finger and a coolant tube for transferring heat away from each ice growth region;

means for introducing water into the icemaking tube so that at least a portion of the water freezes into ice at the ice growth regions; and

a power supply for periodically supplying a pulse of electrical power to a heater in thermal contact with the tube, to melt at least an interfacial layer of the ice to detach the ice from the tube.

26. Pulse electrothermal ice detachment apparatus comprising:

a plurality of icemaking tubes;

one or more of cold fingers and coolant tubes for transferring heat away from ice growth regions of each icemaking tube;

means for introducing water into each icemaking tube so that at least a portion of the water freezes into ice at the ice growth regions; and

a power supply for periodically supplying a pulse of electrical power to each tube, to melt at least an interfacial layer of the ice to detach the ice from each tube.

27. Apparatus of claim 26, wherein the icemaking tubes form a plurality of groups, and the power supply periodically supplies a pulse of electrical power to one group at a time.

28. Apparatus of claim 27, comprising apparatus for determining when to harvest the ice in each group by capacitively sensing the ice of each group, by optically sensing the ice of each group, by determining the weight of the ice of each group, by determining an elapsed icemaking time of each group or by determining that water flow is impeded by ice of each group.

29. Pulse electrothermal ice detachment apparatus, comprising:

one or more coolant tubes in thermal contact with an evaporator plate; and

one or more heaters disposed adjacent the evaporator plate and between the coolant tubes, the one or more heaters being configured for converting electrical power to heat, so that ice detaches from the evaporator plate.

30. Apparatus of claim 29, each of the one or more heaters comprising a metal layer.

31. Apparatus of claim 30, each of the one or more heaters further comprising a dielectric layer between the metal layer and the evaporator plate.

32. Pulse electrothermal ice detachment apparatus, comprising:

one or more coolant tubes in thermal contact with an evaporator plate; and

a heater disposed between the coolant tubes and the evaporator plate, the heater being configured for converting electrical power to heat, so that ice detaches from the evaporator plate.

33. Apparatus of claim 32, each of the one or more heaters comprising a metal layer.

34. Apparatus of claim 33, each of the one or more heaters further comprising a dielectric layer between the metal layer and the evaporator plate.

35. Apparatus of claim 33, further comprising a dielectric layer between the metal layer and each of the one or more coolant tubes.

36. Freezer unit configured as a heat-storage icemaking system, comprising:

a freezer unit having a compressor and a condenser for dissipating waste heat;

coolant that circulates through the compressor, the condenser and a coolant tube, the coolant tube being in thermal contact with an evaporator plate;

a tank, after the compressor and before the condenser, that transfers heat from the coolant to a heating liquid;

wherein the heating liquid periodically flows through a heating tube in thermal contact with the evaporator plate, to detach ice from the evaporator plate.

37. Freezer unit of claim 36, wherein the coolant tube and the heating tube couple with the evaporator plate in an alternating sequence.

38. Freezer unit of claim 36, comprising a pump for pumping the heating liquid.

39. Freezer unit of claim 38, wherein the evaporator plate is disposed at a higher level than the tank, and the heating liquid drains to the tank when the pump is not operating.

40. Freezer unit of claim 36, comprising a pump for pumping the heating liquid from a heating liquid reservoir to the tank.

41. Freezer unit of claim 40, wherein

the tank is disposed at a higher level than the evaporator plate, the heating liquid flowing through the heating tube upon opening of a valve between the tank and the heating tube;

and

the evaporator plate is disposed at a higher level than the reservoir, the heating liquid draining to the reservoir after the ice is detached.

42. Freezer unit of claim 40, wherein

the tank is isolated by an inlet valve between the pump and the tank, and an outlet valve between the tank and the heating tube;

the heat increases pressure within the tank when the inlet and outlet valves are closed;

the pressure forces the heating liquid into the heating tube, to detach the ice, when the outlet valve opens; and

after the ice is detached, the outlet valve closes, the inlet valve opens, and the pump returns the heating liquid to the tank.

43. A method for detaching ice from at least one of a coolant tube, cooling fins and an evaporator plate of a refrigeration unit, comprising

transferring heat from a coolant to a heating liquid during an icemaking or refrigeration mode;

accumulating ice on at least one of the coolant tube, cooling fins and evaporator plate during the icemaking or refrigeration mode, and

flowing the heating liquid through heating tubes in thermal contact with at least one of the coolant tube, cooling fins and evaporator plate to detach the ice.

44. Method of claim 43, further comprising stopping the icemaking or refrigeration mode during the step of flowing.

45. Method of claim 43, further comprising evacuating the heating liquid from the heating tubes when the step of flowing is complete.

46. Pulse electrothermal ice detachment apparatus comprising:

a heat exchanger having a coolant tube in thermal contact with heat exchanging surfaces; and

a power supply electrically switched to the heat exchanger for pulse heating.

47. System of claim 46, at least one of the heat exchanging surfaces comprising insulation formed from anodized aluminum or anodized aluminum alloy, the power supply being electrically switched to a conductive film disposed on the insulation.

48. System of claim 46, wherein the conductive film is a metal layer applied by one of CVD, PVD, electroless coating and painting.

49. System of claim 46, wherein the heat exchanger is an accordion type heat exchanger.