Traditional corrugated tube heat exchangers are suitable for various food industry applications. However, these exchangers are less adept at handling more challenging processes. Examples include pasteurising or cooling dense products such as creams, sauces, and meat products.
Therefore, an alternative solution is required. Scraped surface heat exchangers use scrapers, as suggested by their name, to consistently remove the product from the tube surface to prevent a build-up, which would otherwise hinder the heat transfer.
Secondly, the scrapers mix product as it passes through the heat exchanger creating an evenly heated product. Lastly, the scrapers assist in pushing the product through the heat exchange tube.
Two models of the scraped surface heat exchangers are available, the Uniscus Series and the R Series. The Uniscus Series provides a reciprocated scraper movement that cleans the heat exchanger surface, enhancing heat transfer by creating turbulence. However, the R Series uses a rotating helical screw that keeps the tube clean and accelerates product movement through the tube.
When comparing the two models, the Unisces Series is designed and more suitable for products that require a more gentle application, such as creams or products with particles that must be kept intact. The rotating R Series is better suited for products that require and benefit from vigorous handling and mixing, such as mixed fruit purees.
Due to the scraper surface heat exchangers' design, they are best suited for viscous food products with high fouling potential, such as creams, sauces, purees, minced meat, and other similar products.
When deciding between models, it is essential to note that the R Series is more suitable if the pressure drop and the rate of temperature change will affect the product and how you recover it from the tube. The pressure drops of both designs are much higher than that of other heat exchangers, which in certain instances, can create a shearing force that splits or damages the product, especially sauces and emulsions.
The Uniscus Series scrapers are controlled individually, the speed of which can be altered to the needs of a specific product to optimise results. The scrapers move back and forth inside the heat exchanger's interior, which is both hygienic and improves the heating of the product.
In contrast, the R series pressure drop is much less than its counterpart, which reduces both energy consumption and helps maintain heat transfer efficiency. Its unique helical screw has a significant gap within the tube which significantly increases product turbulence, improves mixing, and avoids product build-up.
For more information regarding either product and which is more suited, visit the HRS website.
