Method of defrosting an energy recovery ventilator unit

• US 10,386,087 B2
• Filed: 09/19/2017
• Issued: 08/20/2019
• Est. Priority Date: 11/10/2011
• Status: Active Grant

• Current Assignee: Lennox Industries Incorporated (Lennox International Incorporated)
• Original Assignee: Lennox Industries Incorporated (Lennox International Incorporated)
• Inventors: McKie, Justin, Perez, Eric, Thomas, Herman Marcus, Schneider, Steve
• Primary Examiner(s): Norman, Marc E
• Application Number:
  US15/708,530
• Publication Number:
  US 20180003404A1
• Time in Patent Office: 700 Days
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/41 Defrosting; Preventing freezing
• CPC Class Codes: F24F 12/006 using an air-to-air heat exchanger F24F12/002 takes precedence
• CPC Class Codes: F24F 2140/30 Condensation of water from cooled air

Abstract

A method of defrosting an energy recovery ventilator unit. The method comprises defrosting an energy recovery ventilator unit. The method comprises activating a defrost process of an enthalpy-exchange zone of the energy recovery ventilator unit when an air-flow blockage in the enthalpy-exchange zone coincides with a frost threshold in the ambient environment surrounding the energy recovery ventilator unit. The method also comprises terminating the defrost process when a heat transfer efficiency across the enthalpy-exchange zone returns to within 10 percent of a pre-frosting heat transfer efficiency wherein, the heat transfer efficiency is proportional to a temperature difference between an intake air zone of the energy recovery ventilator and a supply air zone of the energy recovery ventilator divided by a temperature difference between an return air zone of the energy recovery ventilator and the intake air zone.

Claims

1. A method of defrosting an energy recovery ventilator unit, the method comprising:

establishing a pre-frosting operating condition of an enthalpy-exchange zone of the energy recovery ventilator unit;

determining if an air-flow blockage exists in the enthalpy-exchange zone;

determining if a frost threshold exists in an ambient environment surrounding the energy recovery ventilator unit;

responsive to a determination that the air-flow blockage and the frost threshold coexist, activating a defrost process of the enthalpy-exchange zone;

establishing a defrosting operating condition of the enthalpy-exchange zone during the defrost process;

terminating the defrost process when the defrosting operating condition is within 10 percent of the pre-frosting operating condition; and

wherein activating the defrost process further comprises activating a heat source of an air-handling unit coupled to and located downstream of the energy recovery ventilator unit.

2. The method of claim 1, wherein activating the defrost process further comprises activating a heat source configured to warm air in an air intake zone of the energy recovery ventilator unit.

3. The method of claim 2, wherein activating the heat source further comprises adjusting the heat source to one of a plurality of different levels of heat generation as a function of an ambient air temperature surrounding the energy recovery ventilator unit.

4. The method of claim 1, wherein activating the defrost process further comprises activating a heat source configured to warm air in an exhaust air zone of the energy recovery ventilator unit.

5. The method of claim 4, wherein activating the heat source further comprises adjusting the heat source to one of a plurality of different levels of heat generation as a function of an ambient air temperature surrounding the energy recovery ventilator unit.

6. The method of claim 1, wherein activating the defrost process further comprises reducing airflow between an air intake zone of the energy recovery ventilator unit and the enthalpy-exchange zone.

7. The method of claim 1, wherein activating the defrost process further comprises activating an air controller assembly configured to continuously adjust airflow through an air intake opening connected to a supply zone of the energy recovery ventilator unit.

8. The method of claim 1, wherein activating the defrost process further comprises reducing airflow between an air intake zone of the energy recovery ventilator unit and the enthalpy-exchange zone and activating an air controller assembly to allow airflow through an air intake opening connected to a supply zone of the energy recovery ventilator unit.

9. The method of claim 1, wherein activating the defrost process further comprises:

activating an air controller assembly to allow airflow through an air intake opening connected to a supply zone of the energy recovery ventilator unit;

activating a heat source of an air-handling unit coupled to and located downstream of the energy recovery ventilator unit; and

wherein activation of the heat source is prior to or simultaneously with the activation of the air controller assembly.

10. The method of claim 1, wherein:

establishing the pre-frosting operating condition further comprises measuring a pre-frosting pressure difference across the enthalpy-exchange zone; and

establishing the defrosting operating condition comprises measuring a defrosting pressure difference across the enthalpy-exchange zone.

11. The method of claim 1, wherein:

establishing the pre-frosting operating condition further comprises measuring a pre-frosting heat transfer efficiency across the enthalpy-exchange zone; and

establishing the defrosting operating condition comprises measuring a defrosting heat transfer efficiency across the enthalpy-exchange zone.

12. A method of defrosting an energy recovery ventilator unit, the method comprising:

establishing a pre-frosting operating condition of an enthalpy-exchange zone of the energy recovery ventilator unit;

determining if an air-flow blockage exists in the enthalpy-exchange zone;

determining if a frost threshold exists in an ambient environment surrounding the energy recovery ventilator unit;

responsive to a determination that the air-flow blockage and the frost threshold coexist, activating a defrost process of the enthalpy-exchange zone;

establishing a defrosting operating condition of the enthalpy-exchange zone during the defrost process;

terminating the defrost process when the defrosting operating condition is within 10 percent of the pre-frosting operating condition; and

wherein activating the defrost process further comprises activating an air controller assembly configured to continuously adjust airflow through an air intake opening connected to a supply zone of the energy recovery ventilator unit.

13. The method of claim 12, wherein activating the defrost process further comprises activating a heat source configured to warm air in an air intake zone of the energy recovery ventilator unit.

14. The method of claim 13, wherein activation of the heat source is prior to or simultaneously with the activation of the air controller assembly.

15. The method of claim 13, wherein activating the heat source further comprises adjusting the heat source to one of a plurality of different levels of heat generation as a function of an ambient air temperature surrounding the energy recovery ventilator unit.

16. The method of claim 12, wherein:

establishing the pre-frosting operating condition further comprises measuring a pre-frosting heat transfer efficiency across the enthalpy-exchange zone; and

establishing the defrosting operating condition comprises measuring a defrosting heat transfer efficiency across the enthalpy-exchange zone.

17. A method of defrosting an energy recovery ventilator unit, the method comprising:

establishing a pre-frosting operating condition of an enthalpy-exchange zone of the energy recovery ventilator unit;

determining if an air-flow blockage exists in the enthalpy-exchange zone;

determining if a frost threshold exists in an ambient environment surrounding the energy recovery ventilator unit;

responsive to a determination that the air-flow blockage and the frost threshold coexist, activating a defrost process of the enthalpy-exchange zone;

establishing a defrosting operating condition of the enthalpy-exchange zone during the defrost process;

terminating the defrost process when the defrosting operating condition is within 10 percent of the pre-frosting operating condition; and

wherein activating the defrost process further comprises reducing airflow between an air intake zone of the energy recovery ventilator unit and the enthalpy-exchange zone and activating an air controller assembly to allow airflow through an air intake opening connected to a supply zone of the energy recovery ventilator unit.

18. The method of claim 17, wherein activating the defrost process further comprises activating a heat source configured to warm air in an air intake zone of the energy recovery ventilator unit.

19. The method of claim 18, wherein activation of the heat source is prior to or simultaneously with the activation of the air controller assembly.

20. The method of claim 18, wherein activating the heat source further comprises adjusting the heat source to one of a plurality of different levels of heat generation as a function of an ambient air temperature surrounding the energy recovery ventilator unit.