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 artificially fouled could be 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 and an aluminium brass tube of 24.5mm o.d. were used for the test. The water velocity and fouling factor weve varied from 0.8 to 2.5m/s and up to 2 × 10^-4m²K/W, respectively. Prior to the test, dimensionless relations between tube wall temperature at the heated area, mean velocity and fouling factor along with their dependence on water temperature were derived from the results of numerical calculation of the temperature distribution near the heated area. The maximum errors for water velocity Δu and fouling factor ΔR in the test are as follows: Δu=2.4% for clean tubes, ΔR=0.5×10^-5m²K/W for given water velocity, and ΔR=2×10^-5m²K/W and Δu=±20% for the simultaneous measurement.