Measurement of Temperature, Concentration, and Velocity in Laminar Flow Using a Single Wire Probe

The measurement of three physical quantities: temperature, concentration and velocity in laminar flow using a single metal wire probe with an applied AC voltage was studied. The measurement setup is simple; it contains a thin metal wire, a bridge circuit and a lock-in amplifier. Furthermore its operation is very straight forward, thus it is a useful technique for heat and mass transfer research and monitoring of industrial processes. For the temperaure and velocity measurement the same principle used in the RTD and hot wire anemometer method is applied in AC mode. Whereas the 3w method was used for concentration measurement in forced convection. Measurement condition and performance is discussed for each measurement. Using a measurement example for flow composed of two liquids in a rectangle channel, it is shown that profiles of three physical quantities are measured like what is expected by this method, however the velocity and concentration measurement are delicate and improvement of accuracy is necessary.