Development of Non-contact Scraped Surface Heat Exchanger

Abstract

In order to develop the non-contact scraped surface heat exchanger with the non-contact scraper blades, experiments were performed for cooling corn syrup water solution as a test process fluid flowing in a typical scraped surface heat exchanger with a constant clearance between the scraper blade and the heat transfer surface. The local heat transfer coefficient and the power consumption were measured by varying the flow rate and the viscosity of test process fluid, and the rotational speed of scraper blades for the some constant non-contact clearances in the different scraped angles. Based on these experimental data, the effects of the non-contact clearance and the scraped angle on Nusselt number and Power number were examined in comparison with these correlations for the perfect contact scraped surface heat exchanger with the blades pressed to the heat transfer surface by springs. As a result, it was clarified that Nusselt number and Power number in case of the noncontact clearance 0.2 mm had decreased from those in the perfect contact scraped surface heat exchanger by 0 30 % with an increase in rotational Reynolds number and by 60 % on the whole, respectively.