Non-invasive, energy-autonomous and wireless temperature sensor for the process industy

Temperature sensors for application in the process industry are typically mounted in a thermowell. These tubular fittings penetrate the surface of e.g. a pipe and allow to insert a temperature sensing element into the process medium. Although this invasive sensing is state-of-the-art, thermowells suffer from significant drawbacks: Any pipe penetration is a potential cause for leakage and the thermowell itself is prone to corrosion, abrasion and bending stress. Avoiding the thermowell by measuring temperature on the surface of the process container was so far not considered a widespread alternative to invasive sensing. The temperature of the surface is generally not considered representative for the temperature of the process medium. A surface sensor is strongly exposed to the ambient condition and, furthermore, the calibration of such a surface sensor is challenging. In this paper we demonstrate how to overcome these limitations by an optimized thermo-mechanical design and enhanced model-based sensing. In combination with energy autonomous operation and wireless communication our novel non-invasive sensor offers a remarkable flexibility enabling scenarios discussed within the context of internet of things (IoT).