Experimental Verification of a Method for Simultaneous Measurement of the Fouling Factor and Water Velocity inside a Condenser Tube

The fouling factor and mean water velocity inside a condenser tube, which is artificially fouled, are simultaneously measured by means of local heating from the outside of the tube with two heaters of different lengths. The principle of the measurement is based on heat-transfer characteristics which depend on heater length. A titanium tube of 24.16 mm i.d. and an aluminum brass tube of 22.77 mm i.d. are used for the test. The test ranges of water velocity and fouling factor are 0.8-2.5 m/s and 0-2×10^-4 m²K/W, respectively. Prior to the test, dimensionless relations among tube wall temperature at the heated area, mean water velocity and fouling factor along with their dependence on water temperature are derived from the results of numerical calculation of the temperature distribution near the heated area. The maximum errors for water velocity ΔU and fouling facter ΔR in the test are as follows; ΔU=2.4% for clean tubes, ΔR=0.5×10^-5 m²K/W for given water velocity, and ΔR=2×10^-5 m²K/W and ΔU=±20% for the simultaneous measurement.