Generic studies for industrial heat exchanger fouling
report
As part of the European CEC Project Joue-0040-C 'Generic Studies for Industrial Heat Exchanger Fouling' a study was undertaken to develop a gas-side fouling pilot monitor. The monitor device is designed to provide an indication of the progress of fouling within a heat exchanger. The increase of the temperature and the change of the emission coefficient ofthe heat exchanger surfaces indicate fouling. The measuring principle for the monitor is the measurement of infra-red radiation emitted from the fouled surface of a heat exchanger at three or more wavelengths. The temperature and the emissivity of the fouled surface are computed by iterative fitting of the Planck equations. A camera set-up is selected. This presents the possibility of obtaining images of streaks ofthe surface, thus measuring the temperature and the emissivities at different locations on a fouled heat exchanger pipe. A laboratory test facility is set up in order to test the principle ofthe monitor. The aim of the laboratory tests is to verify the surface temperatures and the emission coefficients measured and calculated by the monitor. The results of the laboratory tests showed that the temperatures calculated by the software differ in some cases by more than 10 "C from the temperature measured by a thermocouple and that the emission coefficient in some cases differs by more than 10 % from the real emission coefficient. These large differences are probably caused by the relatively large fluctuations in the measured data. Expectations are that improvement in the stability ofthe measuring method will improve the quality ofthe input data of the iteration program. This will probably result in a more exact calculation of the surface temperatures and emission coefficients.
Topics
TNO Identifier
253257
Publisher
TNO
Collation
45 p.
Place of publication
Apeldoorn