Heat transfer during ice slurry production in a scraped surface plate heat exchanger (SSPHE) has beenexperimentally investigated. By using a 7 wt. % sodium chloride brine, a wide range of operatingconditions has been tested: scraping velocities from 0.1 to 0.8 s−1 and logarithmic temperaturedifferences from 0.5 to 2.5 °C. Two different PEEK scraper arrangements have been used, mounted onthe driving arms: rigid scrapers and surface adaptable scrapers, pushed by torsion springs. Heat transfercoefficients and ice production rate were measured under batch operating mode. Experimental resultsshown dependence of the nucleation onset with the scraping speed and the wall supercooling degree.Global nucleation only occurred for high velocities and low supercooling degrees, appearing only on thewall for the other cases. A decrease of the heat transfer coefficient of 1.5 times for increasing logarithmictemperature differences is reported, as a consequence of the ice layer growth with a low effect of thescraping speed. The use of adaptable scrapers provide heat transfer coefficient augmentations from 2 to4-fold with respect to the rigid configuration.
展开▼
