Designing and application of a shell and tube heat exchanger for nanofluid thermal processing of liquid food products

Abstract

AbstractOne of the most commonly used types of heat exchangers is the shell and tube heat exchanger. It has been well established that applications of nanofluids in shell and tube heat exchangers are a competitive alternative for common industrial fluids such as hot water. However, conventional applications of nanofluids are restricted to nonfood industries. So, for the first time, this study aimed to design a shell and tube heat exchanger through Kern method for food applications and involving different equations and calculations in detail, to deploy intelligent thermal equipment and PLC section for controlling the performance of shell and tube heat exchanger, and finally, to apply that heat exchanger for two food products, that is, watermelon and tomato juice, in order to survey the extent to which this equipment, by using nanofluids rather than common hot water systems, can improve temperature–time profile of food systems and diminish their energy consumption. Kern method could accurately estimate the number of tubes, tube pitch, baffle spacing, tubes per pass, as well as shell‐side, tube‐side, and overall heat transfer coefficients while maintaining pressure drops in acceptable ranges. Application of 2 and 4% alumina nanofluids, instead of hot water, decreased thermal processing time of watermelon juice by 24.14 and 51.72%; similarly, these reduction rates were 22.3 and 48.76% for tomato juice processing. Consequently, energy consumption rates of watermelon juice processing dwindled to 24.64 and 48.34% and of tomato juice to 22.3 and 48.76% through deployment of 2 and 4% Al2O3, compared to hot water, respectively.Practical applicationsFluids with suspended particles of nanometals or oxidized metals benefit from better heat transfer properties. There is limited research dealing with effects of adding nanoparticles to conventional thermal fluids for fruit juices processing. So, the goal of this research was to introduce nanofluid technology for thermal processing of food products, increasing heat transfer efficiency in shell and tube exchangers by nanofluids and frugality in energy consumption for pasteurization, reducing thermal processing duration and better quality retention of food products.