Fisher & Paykel Aerosmart DE27CW1 - How Does Aerosmart Dry Clothes; Auto Sensing

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How Does AeroSmart Dry Clothes?
Auto Sensing
The Principle…
When wet or damp clothes are loaded into a dryer they are partially saturated with
water, which is a relatively good conductor of electricity. In the AeroSmart Dryer we use
Sensor Bars to measure the conductivity. When moisture in the clothes touches across
the Sensor Bars (located beneath the lint bucket) their conductivity is measured. As the
clothes dry they become less conductive, and it is this measurement that is used to
calculate the dryness of the clothes load.
Large loads will brush against these moisture sensor bars more frequently than small
loads, and this strike count is used to help determine the dryness of different sized loads.
Different fabrics retain moisture differently; a thick towel containing a lot of moisture will
often conduct the same as a light synthetic garment containing very little. It is this
difference in fabric characteristics plus the initial unknown moisture content that makes
the calculation of dryness reasonably complex. This is also the reason why loads need to
be sorted, particularly Delicate from non-Delicate items.
A temperature sensor located in the exhaust duct is used to limit the temperature of the
various cycles. The temperature limits are to provide clothes care for the different fabric
types. The table below shows the temperature limits in the exhaust for the various
cycles:
Regular Sheets Heavy Delicate Easy Iron Casual Air Dry
Max Exhaust
Temperature
149°F
(65°C)
149°F
(65°C)
149°F
(65°C)
127°F
(53°C)
140°F
(60°C)
140°F
(60°C)
Room
Temp
The clothes in the drum will be slightly hotter than these temperatures as the air has
cooled down slightly by the time it reaches the
exhaust.
Information Used for Auto Sensing:
Each time a strike is made across the Sensor Bars
the measurement of conductivity is recorded.
During each minute the lowest resistance
measurement is recorded, as well as a
measurement of the number of strikes which are
averaged with previous measurements. These
two measurements are used to calculate the
dryness of a clothes load. In Smart Tool the
averaged lowest resistance is called Trend and
the number of strikes is called Strike Count.
Strike Count
Trend
Calculated dryness (%)
Exhaust Temperature
Lowest Resistance