CFD of coupled multiphysics in scraped surface heat exchangers

Scraped surface heat exchangers (SSHE) are widely used in (for example) the food industry, where there is a requirement for heat exchange, crystallization, aeration and other continuous processes. The SSHE is particularly useful for heavy viscous fluids, where classical modes of heat transfer (i.e. turbulence) are not available. In the SSHE, a set of rotating blades continually scrape the process fluid from the inside of the heat exchange vessel; high heat transfer rates are maintained by the continual replacement of material in the near wall region.

In many food processing applications, the final product behaviour and characteristics are intimately linked to the processing history of the fluid. Consequently, there are challenges when moving between product lines to ensure the correct product properties (i.e. heat transfer and crystallisation)—the same SSHE might produce radically different results with different ingredient blends. This project will initially simulate the coupled evolution of water/ice mixes undergoing heat transfer, with a view to extending the work to emulsions and aerated liquids. The work will build on previous (experimental characterisation) of a number of SSHEs, but will seek to develop a set of generalised design principles and scaling rules. This research activity is part of a large multi-university project looking at the processing of structured fluids and—parallel to this project—ongoing experimental work is underway to provide experimental validation of a number of SSHEs using different representative process fluids.

Areas of expertise: MACEthermofluids