UNCERTAINTY IN MEASUREMENTS OF FLUID TEMPERATURE IN TUBES

Temperature measurements of fluid in tubing is common practice in many applications of biology and medicine for the purpose of temperature c ontrol, analysis, and modeling. Thermocouples are commonly applied for those measurements and, ignoring the thermal interaction between the thermocouple and the fluid, it is widely assumed that the thermocouple 's tip reads the undisturbed fluid temperature. The current report pro vides a simple and explicit formulation for the estimation of the effe ct of this thermal interaction on the measured temperature value. Resu lts show that this thermal effect, between the sensor and the sensed p henomenon, may result in an uncertainty in measurements which overwhel ms uncertainties from other sources.