EFFECT OF SURFACE TEMPERATURE ON THE FOULING OF HEAT TRANSFER SURFACES

Abstract

The surface temperature is one of the important parameters affecting the surface fouling. To study this effect, an experimental test rig has designed and I constructed. The experimental loop has a Perspex test tube of 300 em length, 5.53cm inner diameter, and 3mm thickness. Water with a solid particle I concentration of lgm/lit is used as a test fluid. Three electric heaters are fixed in series arrangement at the center of the test tube. I A circulating pump has been used to circulate the test fluid with a constant velocity . To have a closed loop experimental test rig, a water cooler has been used to obtain a constant inlet temperature. The surface temperature of electric heaters and test fluid temperature at each section of test tube are observed and recorded by a digital temperature recorder. The heating water flows in a closed I loop to keep constant solid particle concentration. The experimental runs have been carried out under different surface I temperatures (from 55°C to 95°C) with a constant flow velocity of 0.08 m/s. All experimental runs have been carried out for a long time each to surface I temperature (about 280hrs) to reach the asymptotic fouling.

The obtained results have been analyzed and studied. From the discussion, it can be concluded that, the fouling resistance and the asymptotic fouling resistance decrease with increasing the surface temperature. The delay time is very small and seems to approach zero in all experiments that is due the high concentration of the foulant (about lgm/lit). The saw teeth effect have been obtained in all runs.