Thermal Effusivity (W√s/m2K) is described as a materials ability to exchange heat with its surroundings. Surface haptics is a branch of psychology, describing the sense of touch, localized to the skin surface. The feeling of warmth and coolness (thermal effusivity) makes up the feeling of comfort, or the desired effect, which goes into the touched material surface. This is an important field of measurement for textiles, fabrics and solids.
The TPS-EFF (Transient Plane Source-EFFusivity) is a portable meter for direct determination of thermal effusivity of textiles and other low effusivity materials, in accordance with ASTM D7984-16. With a single measurement of 2 or 10 seconds in duration, materials can be accurately measured for thermal effusivity.
The TPS-EFF uses a single-sided 30 mm diameter TPS sensor and short test times, to ensure one-dimensional heat flow. During the measurement, the sensor is heated using a constant current source, while the temperature rise of the sample is simultaneously recorded with time, by monitoring the change in electrical resistance of the wire spiral. The slope of temperature against a special function of time, is used to calculate the thermal effusivity of the material. For materials of relatively high effusivity, the slope will be lower, than materials of low effusivity.
|Materials||Textiles, Fabrics and Solids|
|Thermal Effusivity Range||35 to 1700 W√s/m2K|
|Measurement Time||2 and 10 seconds|
|Temperature Range1||-10 to 50°C|
|Minimum Sample Size||35 mm diameter x thickness dependent on Effusivity|
|Maximum Sample Size||Unlimited|
|Moisture Range||0 to 90% (non-condensing)|
|Sensor Diameter||30 mm|
|Test Method||Transient Plane Source (TPS)|