A speed of sound based feed water temperature sensor

Controlling thermal power in the feed water line of a power plant presupposes both accurate flow and temperature measurement. In this application the temperature measurement is usually a single Pt-100. This results in a measurement error of several kelvin. In this study we have investigated two different sensors based on the speed of sound (SoS) in the flowing medium for measuring the average temperature across a flow pipe cross-section. This is a task within the on-going European research project called ENG-06. The two SoS-based temperature measuring sensors were investigated under laboratory conditions. Investigations were done using both homogenous and non-homogenous temperature distributions with temperature differences up to 25 K. In addition the influence of pressure (50-200 kPa) and flow rates (0.5-2 m/s) on the SoS devices were also investigated. Our results show that the SoS-based temperature principle is working. Furthermore, depending on the measurement conditions a SoS temperature measurement ...