Flow profiles of power law fluids in scraped surface heat exchanger geometry using MRI

Scraped surface heat exchangers (SSHE) are prevalent in the food industry t o heat/cool viscous fluids and to provide enhanced mixing. This work focuse d on developing and verifying a theoretical model to characterize the flow patterns in two-dimensional angular flow in an SSHE geometry under isotherm al conditions. Experimentally, the model was verified by a noninvasive magn etic resonance imaging (MRT) technique. Good agreement was achieved between the theoretical model and experimental data for a polyalkylene glycol, whi ch behaved as a Newtonian fluid (n = 1), and a 1% CMC solution, a power law fluid with n = 0.77. However, the experimental flow profile tomato puree w as characterized by apparent wall slip. The best fit, with respect to the p ower law model, was a flow behavior index of 0.11. This study provides the framework to quantify the effects of heat transfer on flow profiles in this geometry and the effectiveness of mixing.