Dynamic calibration and modeling of a cold wire for temperature measurement

The dynamical behavior of cold wires and their supporting structure is investigated. It is shown that conventional cold wires have a much more limited frequency response than previously believed, which can cause substantial inaccuracies in temperature data. Here, a lumped parameter model that accounts for the effects of end conduction and wire response is developed. The model is verified by comparing to the experimental data, where the frequency response of the wire is investigated under different heating conditions, with convincing agreement. All the parameters in the model can be found from the geometry of the sensor and the properties of the materials used in its construction. The new model can either be used as a sensor design and optimization tool, in order to design better sensors, or it can be used to correct the data acquired with conventional cold wire sensors, with non-negligible end-conduction effects, so that accurate measurements can be obtained.