HFP01SC info note
Application as heat transfer coefficient sensor
When mounted on top of an object, the HFP01SC self-calibrating heat flux
sensor can be used to determine the local heat transfer coefficient. Although
the measurement result is qualitative rather than absolute, it is very useful in
building physics, and studies of heat transfer and drying processes. The
possibility of comparing different flow regimes offers good experimental data to
check modeling.
See also the scientific section on heat flux.
See also the normal application of HFP01SC
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HFP01SC is a combination of a heat flux sensor and a film heater. The primary
purpose of the sensor is to measure the heat flux through the object on which it
is mounted. The output is a voltage signal that is proportional to the local
heat flux. The film heater that is mounted on top can be activated to generate a
well-known heat flux j. The response of the heat flux plate is measured. The
heat flow will divide between a flow to the object ,j obj, and a flow
to the air, j air. From a thermal point of view the flux experiences
two parallel resistances; to the air and to the object. The thermal resistance
to the air is inversely proportional to Ctr. The thermal resistance
from the heater into the object is always the same (for one installation) within
the short heating cycle. The essence of this approach is that j obj
can be directly measured using the heat flux sensor. An on-site calibration
under conditions without wind speed (free convection), serves to obtain the
combined resistance of the sensor plus the underlying object (which will differ
from one installation to the other).
Using the calibration results Ctr is calculated from the signal
amplitude during heating. Every heating cycle results in an updated value of the
transfer coefficient. Between heating cycles, the HFP01SC continuously measures
the heat flux.
For more information of the heat flux measurement, see the HFP01SC brochure.
For more detailed information on the physics of the transfer coefficient
measurement, the HFP01SC manual can be consulted. The HFP01SC manual can be
obtained free of charge via e-mail. A program for use in combination with the
Campbell Scientific CR10X is available.
Suggested use
- Scientific grade measurement of heat flux in buildings.
- Study of drying and cooling processes
- Heat transfer studies
Heat flux plate specifications
- Expected accuracy: +/- 5 W/ m2K Accuracy not specified when
exposed to direct sunshine or rain.
- Heating cycle time: 180 s
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