# US 2016/0258668 A1 · Defrost Control Using Fan Data

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- Number: US 2016/0258668 A1
- Document ID: US20160258668A1
- Status: Published application
- Kind: A1
- Application number: 15/154,728
- Filed: 2016-05-13
- Published: 2016-09-08
- Earliest claimed: 2012-11-30
- Assignees: Lennox Industries Inc.
- Applicants: Lennox Industries Inc.
- Inventors: Yi Qu; H. Gene Havard; Jon Douglas; Jeff Mangum
- Web page: https://patentgrep.com/patent/US20160258668A1

## CPC

- F25D 21/02: Detecting the presence of frost or condensate
- F24F 11/30: for purposes related to the operation of the system, e.g. for safety or monitoring
- F24F 11/42: of outdoor units
- F25B 13/00: Compression machines, plants or systems, with reversible cycle (defrosting cycles F25B47/02)
- F25B 47/02: Defrosting cycles
- F25D 17/06: by forced circulation
- F25D 21/002: {Defroster control}
- F25D 21/006: {with electronic control circuits}
- F24F 11/41: Defrosting; Preventing freezing
- F25B 2313/0294: related to the outdoor fan, e.g. controlling speed
- F25B 2700/11: Sensor to detect if defrost is necessary
- F25B 2700/15: Power, e.g. by voltage or current
- F25B 2700/173: of the evaporator fan
- F25B 2700/19: Pressures
- F25B 2700/21174: of the refrigerant at the inlet of the evaporator
- F25D: REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR (refrigerated showcases A47F3/04; thermally-insulated vessels for domestic use A47J41/00; refrigerated vehicles, see the appropriate subclasses of classes B60 - B64; containers with thermal insulation in general B65D81/38; heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants, or materials for the production of heat or cold by chemical reactions other than by combustion C09K5/00; thermally-insulated vessels for liquefied or solidified gases F17C; air-conditioning or air-humidification F24F; refrigeration machines, plants, or systems F25B; cooling of instruments or comparable apparatus without refrigeration G12B)
- F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02)
- F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS

## Abstract

In various implementations, frost in a vapor compression system may be controlled. A property of a fan may be determined. A determination may be made whether a frost event and/or a nonfrost event has occurred based at least partially on the determined fan property.

## Claims

### Claim 1

A method of distinguishing between a frost condition and a nonfrost condition in a vapor compression system, the method comprising:
determining one or more system properties of the vapor compression system, the one or more system properties comprising at least inlet temperature and fan property;
determining if an event has occurred based at least partially on at least the inlet temperature and the fan property;
determining if the event is a frost condition or a nonfrost condition based at least in part upon the inlet temperature and the fan property, wherein if the fan property is greater than a predetermined value and the inlet temperature is above a predetermined temperature then a determination of a nonfrost condition is made, and if the fan property is greater than a predetermined value and the inlet temperature is below a predetermined temperature then a determination of a frost condition is made; and
initiating a defrost cycle if the event is a frost condition.

### Claim 2 (depends on 1)

The method of claim 1 further comprising allowing the vapor compression system to operate in response to a request.

### Claim 3 (depends on 1)

The method of claim 1 wherein one or more of the fan properties comprises at least one of fan speed, air flow rate, external static pressure, input power, change in fan speed, change in air flow rate, change in external static pressure, or change in input power.

### Claim 4 (depends on 1)

The method of claim 1 further comprising allowing the vapor compression system to operate in a defrost mode, if the frost event has been determined to have occurred.

### Claim 5 (depends on 1)

The method of claim 1 further comprising determining a time period over which the fan property changed determining if a frost event has occurred is further based at least partially on the time period.

### Claim 6 (depends on 1)

The method of claim 1 wherein the one or more fan properties comprises temperature.

### Claim 7 (depends on 6)

The method of claim 6 wherein the nonfrost condition comprises soiling of a heat exchanger coil in the vapor compression system.

### Claim 8 (depends on 1)

The method of claim 1 wherein the predetermined temperature is 40 degrees Fahrenheit.

### Claim 9 (depends on 1)

The method of claim 1 further comprising comparing at least one of the determined properties to a predetermined property value; and wherein determining if a frost event has occurred is based at least partially on the comparison of at least one of the determined properties to the predetermined property value.

### Claim 10

A vapor compression system comprising:
a fan;
sensors that measures one or more system properties, the one or more system properties comprising at least inlet temperature and fan property; and
a management module that determines if an event has occurred and whether the event is a frost condition or a nonfrost condition based at least in part upon the inlet temperature and the fan property, wherein if the management module determines that the fan property is greater than a predetermined value and the inlet temperature is above a predetermined temperature then a determination of a nonfrost condition is made, and if the management module determines that the fan property is greater than a predetermined value and the inlet temperature is below a predetermined temperature then a determination of a frost condition is made.

### Claim 11 (depends on 10)

The system of claim 10 wherein the fan comprises an outdoor fan of an air conditioner.

### Claim 12 (depends on 10)

The system of claim 10 wherein the fan comprises a fan of a refrigeration unit.

### Claim 13 (depends on 10)

The system of claim 10 wherein the one or more fan properties comprises at least one of fan speed, air flow rate, external static pressure, input power, change in fan speed, change in air flow rate, change in external static pressure, or change in input power.

### Claim 14 (depends on 10)

The system of claim 10 further comprising a memory storing one or more predetermined property values.

### Claim 15 (depends on 10)

The system of claim 10 wherein the management module further allows a defrost operation if the frost event has occurred.

### Claim 16 (depends on 10)

The system of claim 10 wherein the one or more fan properties comprises temperature.

### Claim 17 (depends on 10)

The system of claim 10 wherein the predetermined temperature is 40 degrees Fahrenheit.