REVERSE CYCLE DEFROST METHOD AND APPARATUS

• US 20120102986A1
• Filed: 06/30/2011
• Published: 05/03/2012
• Est. Priority Date: 06/30/2010
• Status: Active Grant

• Current Assignee: JMC Ventilation Refrigeration LLC (JMC Enterprises Incorporated)
• Original Assignee: JMC Ventilation Refrigeration LLC (JMC Enterprises Incorporated)
• Inventors: Micka, Joel, Decker, Mark
• Granted Patent: US 9,605,890 B2
• Time in Patent Office: Days
• US Class Current: 62/82
• CPC Class Codes: F25B 47/02 Defrosting cycles
• CPC Class Codes: F25D 21/006 with electronic control circuits
• CPC Class Codes: F25D 21/12 by hot-fluid circulating system separate from the refrigerant system
• CPC Class Codes: F25D 2317/0684 the fans allowing rotation in reverse direction

Abstract

Systems and methods for refrigerating crops and other goods and for defrosting a refrigeration system. A refrigerant is circulated between a condenser and a refrigerator to cool air in the refrigerator. Heat is removed from the refrigerant at the condenser. Periodically the cycle of refrigerant and air can be reversed to melt frost in the refrigerator. Frost can be detected by a sensing mechanism and the refrigerant and air cycles can be reversed in response to detecting the frost. The frost can be removed quickly without removing the goods from the refrigerant.

Claims

1. A method of defrosting a refrigeration unit for a crop storage facility, the method comprising:

circulating refrigerant between a condenser and a refrigerator in a first refrigerant direction, wherein the refrigerant absorbs heat in the refrigerator and dissipates heat in the condenser;

circulating a first air flow between thermal contact with the refrigerant and thermal contact with goods in a first air direction, wherein the refrigerant cools the first air flow and the goods warm the first air flow;

passing a second air flow through the condenser in a second air direction to remove heat from the refrigerant; and

removing accumulated frost from the refrigerator by—

circulating the refrigerant in a second refrigerant direction opposite the first refrigerant direction,

circulating the first air flow in a third air direction opposite the first air direction, and

passing a third air flow through the condenser in a fourth direction opposite the second air direction.

2. The method of claim 1, further comprising detecting frost in the refrigerator, and wherein removing accumulated frost is performed in response to detecting the frost.

3. The method of claim 1, further comprising resuming refrigeration operation after removing the accumulated frost by:

circulating the refrigerant in the first refrigerant direction,

circulating the air in the first air direction, and

passing the second air flow through the condenser in the first direction.

4. The method of claim 1 wherein removing the accumulated frost from the refrigerator comprises removing the accumulated frost without removing the goods from the refrigerator.

5. The method of claim 1 wherein passing a second air flow through the condenser in the second air direction to remove heat from the refrigerant comprises using a variable fan drive.

5-1. A refrigeration and defrosting system comprising:

a condenser;

a refrigerator configured to store goods;

a refrigerant circulation path between the condenser and the refrigerator;

a pump positioned in the circulation path and configured to move refrigerant along the refrigerant circulation path in a first refrigerant direction;

an internal air mover configured to circulate a first air flow through the refrigerator in a first air direction to cool the air through thermal contact with the refrigerant, and to direct the first air flow over the goods to cool the goods;

an external air mover configured to direct a second air flow over at least a portion of the condenser and in thermal contact with the refrigerant to remove heat from the refrigerant; and

a controller operably coupled to the pump and to the internal air mover, wherein the controller is configured to reverse operation of the pump and the internal air mover to circulate the refrigerant along the refrigerant circulation path in a second refrigerant direction opposite the first refrigerant direction and to circulate the first air flow in a second air direction opposite the first air direction to melt frost in the refrigerator.

7. The refrigeration and defrosting system of claim 6, further comprising a sensor configured to detect the frost, and wherein the controller is operably coupled to the sensor to reverse operation of the pump and the internal air mover in response to the sensor detecting the frost.

8. The refrigeration and defrosting system of claim 6 wherein the external air mover comprises a variable fan drive.

9. The refrigeration and defrosting system of claim 6 wherein the controller is operably coupled to the external air mover and is configured to reverse operation of the external air mover.

10. The refrigeration and defrosting system of claim 6 wherein the controller is configured to reverse operation of the pump and the internal air mover to melt frost in the refrigerator in a sufficiently short time period that the frost is removed without removing the goods from the refrigerator.

11. The refrigeration and defrosting system of claim 6 wherein the external air mover is configured to reverse the first air flow from the first air direction to the second air direction using at least one of a variable fan drive, a DC electric motor, and contact switching between power leads of a fan motor.

12. The refrigeration and defrosting system of claim 6 wherein the internal air mover is configured to reverse the first air flow from the first air direction to the second air direction using at least one of a variable fan drive, a DC electric motor, and contact switching between power leads of a fan motor.

13. The refrigeration and defrosting system of claim 6 wherein the internal air mover and the external air mover each comprise a plurality of variable fan drives configured to circulate air, and wherein the variable fan drives are reversible.

14. A method of defrosting a crop storage facility refrigeration unit, the method comprising:

refrigerating crops in a refrigerator by moving air in a first air direction and moving refrigerant in a first refrigerant direction;

detecting frost in the refrigeration unit; and

in response to detecting frost in the refrigeration unit, defrosting the refrigeration unit by moving the air in a second air direction and moving the refrigerant in a second refrigerant direction with the goods remaining in the refrigeration unit, wherein the first air direction is opposite the second air direction and the first refrigerant direction is opposite the second refrigerant direction.

15. The method of claim 14, further comprising detecting that the frost has been removed, and in response to detecting that the frost has been removed, refrigerating the crops in the refrigeration unit by moving air in the first air direction and moving refrigerant in the first refrigerant direction.

16. The method of claim 14 wherein refrigerating crops in the refrigerator by moving air comprises pressurizing the air with a variable fan drive.

17. The method of claim 14, further comprising:

directing external air into thermal contact with the refrigerant in a condenser to remove heat from the refrigerant by moving the external air in a first direction;

in response to detecting frost in the refrigeration unit, moving the external air in a second direction opposite the first direction.