# US 8,769,840 B2 · Recirculating dryer

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- Number: US 8,769,840 B2
- Document ID: US8769840B2
- Status: Granted
- Kind: B2
- Application number: 13/471,326
- Filed: 2012-05-14
- Published: 2013-11-14
- Granted: 2014-07-08
- Earliest claimed: 2012-05-14
- Assignees: King Fahd University of Petroleum and Minerals
- Applicants: Memhet Dondurur; Ahmet Z. Sahin
- Inventors: Memhet Dondurur; Ahmet Z. Sahin
- Web page: https://patentgrep.com/patent/US8769840B2

## CPC

- D06F 58/20: General details of domestic laundry dryers (D06F59/00 takes precedence)
- D06F 58/04: Details (controlling or regulating devices D06F34/00)
- D06F 58/24: Condensing arrangements
- D06F 58/38: of drying, e.g. to achieve the target humidity
- D06F 2101/06: Type or material
- D06F 2101/14: Time settings
- D06F 2101/18: Target temperature for the drying process, e.g. low-temperature cycles
- D06F 2103/08: Humidity
- D06F 2103/32: Temperature
- D06F 2103/34: Humidity
- D06F 2103/36: Flow or velocity
- D06F 2105/24: Flow or velocity
- D06F 2105/28: Electric heating
- D06F 2105/32: Air flow control means
- D06F: LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES

## Abstract

The recirculating dryer includes a housing having an operator control panel and a locking door mounted to a side of the housing. A rotating tumbler for holding the laundry to be dried is mounted inside the housing. Heated air is introduced through an inlet of the tumbler, and the outlet is kept closed by a flap. The heated air is recirculated and recycled through the tumbler. The air is reheated back to a predetermined temperature if the temperature falls below a level suitable for drying. A layer of moisture-absorbent material surrounds the tumbler to absorb the moisture gathered in the air from the drying process. At drying completion, the flap is opened to vent the used air. A control system controls various features with data from a thermostat and a moisture detector.

## Claims

### Claim 1

A recirculating dryer, comprising:
a housing having a hollow interior;
an operator control panel disposed on the housing;
a lockable door mounted to a side of the housing, the door being selectively openable to access the interior of the housing;
a rotatable tumbler disposed inside the housing, the tumbler being adapted for holding laundry to be dried, the tumbler having an air inlet and an air outlet;
a selectively actuable flap mounted to the air outlet, the flap being movable into an open or closed position to open or close the air outlet;
a moisture-absorbent layer surrounding the tumbler, the moisture-absorbent layer absorbing moisture from heated air during drying; and
a heater operably connected to the tumbler, the heater being selectively operable to heat air to a selectable drying temperature;
wherein during drying, the flap is closed to allow the heated air to recycle and recirculate through the tumbler in order to minimize energy for heating the air and rotating the tumbler, thereby efficiently using thermal energy from the heated air.

### Claim 2 (depends on 1)

The recirculating dryer according to claim 1, further comprising a control system for controlling drying of laundry, the control system being operatively connected to said heater, the control system having:
a user interface, the user interface being an electronic analog of said operator control panel;
a thermostat for monitoring temperature in said tumbler;
a timer;
a moisture detector for monitoring moisture content in said tumbler;
a tumbler motor for rotating said tumbler; and
a vent motor for opening and closing said flap in order to selectively operate said heater, the tumbler motor and the vent motor based upon data from the user interface, the thermostat, and the moisture detector.

### Claim 3 (depends on 1)

An energy efficient method of drying laundry, comprising the steps of:
providing a recirculating dryer as in claim 1;
heating ambient air to a predetermined temperature, the predetermined temperature being higher than a laundry drying temperature;
closing said flap in order to prevent air and thermal energy loss;
feeding the heated air into said tumbler;
recirculating and recycling the heated air in said tumbler, the heated air gathering moisture from the laundry, causing the predetermined temperature to fall below the drying temperature;
absorbing moisture from the heated air with said moisture-absorbent layer to maintain dryness of the heated air;
reheating the heated air with said heater to raise the temperature of the heated air back to the predetermined temperature; and
opening said flap to exhaust used air upon completion of a drying cycle.