WS01
Sensor for ultra low wind speeds and sensor for leaf boundary layer conductance
WS01 is a sensor that is used
to investigate the heat transfer coefficient, Ctr, from its
surface to the air. The obtained data can be used to determine other
transfer coefficients (for instance for water vapour transport) or local
wind speed (specifically in the low wind speed range). Both measurements
are qualitative rather than absolute. WS01 is suitable for outdoor use. It
has to be used in combination with a proper data acquisition and control
system.
Free: For a nice clear print of the original product
brochure (PDF) click here.
More details on the science: heat flux
and transfer. Hukseflux has prepared a special memo on this application that can be
obtained by e-mail.
For a free copy of the product brochure and this application note click here.
WS01 consists of a heater and a
sensor incorporated in a very thin plastic foil. The sensor in WS01,
consisting of two thermopiles, performs a differential temperature
measurement around the heating wire with record breaking sensitivity.
When placing the sensor in air and
switching on the heater, the sensor output will be inversely proportional to the
heat transfer to the air. The main application of WS01 is as an "artificial
leaf" to study mass transport in the leaf boundary layer. In this application it
is a benefit that WS01 has a leaf-like geometry (flat and thin). Also WS01 can
be used to study local wind speed in the 0.1 to 2 m/s region, for instance in
greenhouses and buildings. This can only be done if there is one predominant
wind direction.
Measurement errors induced by solar
radiation are strongly reduced by the fact that the sensor is symmetrically
placed around the wire, and by using the technique of pulsed heating. The low
thermal mass makes WS01 very fast, reaching thermal equilibrium in 30 s in still
air.
When considering to apply WS01 it is
recommended to consult the manual which is available at Hukseflux. A program for
interfacing with the Campbell Scientific CR10X and CR1000 are available.
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Figure 1
WS01 sensor: thermopiles (1), heating wire (2), cable (3).
Dimensions in mm. |
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| Figure 2 graphs
at different wind speeds: signal amplitude varies with 1/ wind speed or 1/Ctr |
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Suggested use
- As "artificial leaf" in
scientific studies of leaf boundary layer transport.
- As wind speed sensor and heat transfer
coefficient sensor in scientific studies at very low wind speeds.
WS01 sensor specifications
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Thermocouples: 40 Cu-CuNi
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Temperature range: -30
to +80
°C
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Sensor thickness (nominal): 0.15 mm
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Required readout: 2
diff voltage channels 3 V and 5 mV range
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Voltage input: 1-2 VDC
(nominal)
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Interfacing: to most
common datalogging systems
Options
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