Abstract
A new scaling and fouling monitor is described which takes measurements on two heat transfer surfaces rather than one, as is the normal practice. One surface, called the 'test,' is heated. The other surface, called the 'reference,' normally remains unheated. At intervals, comparisons are made between the heat transfer characteristics of the two surfaces. Differential thermal measurements between the two surfaces permit increased sensitivity to heat induced deposition, since compensation for changes in fluid parameters is inherent. Conventional measurements on the unheated reference surface monitor deterioration from non heat transfer induced deposition.
Results are presented of operational experience with units in the laboratory and in the field. Field trials have been primarily on cooling water systems for large building complexes. In the first field trial, the monitoring program included not only these thermal measurements, but also pH, conductivity, daily sodium and calcium concentrations, and corrosion rates of steel and brass.
The purpose of the field test program was two-fold. First, it was designed to monitor the effects of surface metal temperatures on the onset and rate of deposition. Secondly, it was designed to establish operating parameters for the monitor. These parameters would assist establishment of an integrated monitoring program to provide an early warning system of any adverse scaling, fouling or corrosion tendencies of the cooling water in the system.
