This paper reports a study into the fouling of heat exchangers caused by large particles. This type of fouling is a major problem in the agricultural and off-highway environments. The fouling mechanism caused by large particles has been found to be fundamentally different to that caused by small particles. An experimental rig has been developed, which is able to control the velocity, temperature and humidity of the air approaching the heat exchanger. The mass flow rate of the fouling material added to the air flow was controlled to achieve concentrations similar to those encountered in the field. The effects on fouling propensity of various heat exchanger design geometries have been quantified and empirically correlated, and a number of descriptive parameters defined. Some of the findings contradict the perceptions within the industry. For example, the received wisdom has always been that flat fin heat exchangers fouled less than the more modern louvered fin types. Other aspects of design including: core depth; number of tube rows; fin wave and density have also been considered. This has led to empirical correlations between fouling and aspects of heat exchanger design that allow fouling characteristics to be predicted.
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