Abstract
M.Ing.
Deposition of scale on heating surfaces is a major problem in industry as well as
households. The scale that forms on the heating surfaces acts as an insulator and
results in decreased heat transfer effectiveness . These are two main approaches to
prevent or reduce scaling. Although these approaches are claimed to be efficient,
there is a need to evaluate or verify their efficacy. This calls for a method which
should preferably enable quantitative and rapid evaluation of these techniques in
the laboratory.
A reliable, rapid and quantitative measurement method which was comprised of
stripping the scale from heat exchanger pipes with a 10% acetic acid solution and
measuring the Ca concentration in the acid after stripping, was developed. A total
of 11 tests, 7 to test the reproducibility, 2 to test a physical water treatment device
and 2 to test the effect of zinc, were conducted. The reproducibility amongst
different pipes, and amongst different experiments could not be achieved. Attempts to explain the inconsistency through statistical analysis of the data
showed that, the inconsistency in the results could partly attributed to chemical
differences, particularly changes in calcium concentration and TDS. Metal
contamination, particularly zinc could also be responsible for a part of the
inconsistency.