A model for fouling of plate-and-frame heat exchangers in food industry

ABSTRACT Fouling of plate‐and‐frame heat exchangers is considered a major problem in food industries. The presence of microorganisms creates the problem. They grow inside the microchannels of heat exchanger's plates. This leads to a rise in the pressure drop across the exchanger and consequently costs billions of dollars every year due to cleaning operations and even sometimes need replacement of exchanger. This article demonstrates the effects of major factors in fouling formation including fluid velocity, temperature and particulate concentration in plate‐and‐frame heat exchangers used in milk industry. The variation of the overall heat transfer coefficient is determined after fouling formation. Then, to demonstrate the heat and hydraulic effects in a plate heat exchanger, the concept of ‘fouling threshold model’ which was developed for quantifying and mitigating fouling in crude oil processing is extended to model the fouling of 1% Whey protein concentration (WPC) solution. Using this model, curves for fouling threshold of milk are determined and therefore the sensitive exchangers prone to fouling can be identified easily for plant engineers to cleaning program. The predicted values given by the proposed model are compared with experimental results with quite good agreement. In addition, the effects of fouling are added to the model through the overall heat transfer coefficient correlation. © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.