Theoretical Consideration of Simultaneous Measurment of Flow Rate and Fouling Factor

A method for the simultaneous measurement of flow rate in a tube and fouling factor at the inner surface is proposed based on numerical calculations for turbulent heat transfer from a thick tube wall which is heated from the outer surface. Overall heat transfer characteristics depend on the heated length, flow rate and fouling factor of a given tube. Therefore, by substituting the measured data on temperature, at the outer tube surfaces heated by given heat fluxes for short and long heated sections, into simultaneous equations which are derived in the present paper, the values of flow rate and fouling factor can be obtained. Some examples are presented for a condenser tube of aluminium brass and titanium. The estimated accuracy is about several percent for flow rate and several tens per cent for fouling factor, though these values depend on the accuracy of temperature and heat flux measurements. Methods for improving the accuracy are discussed.