Enhanced Heat Transfer with Nanofluid Media: Principles, Methods, and Applications in Dairy Industry
Heat transfer (HT) is a fundamental transport process that plays an indispensable role in almost all unit operations (heating, cooling, freezing, frying, evaporation, drying, and concentration) in the dairy industry. Conventionally, HT is affected by media such as water, oil, brine, air, ethylene glycol, and ethyl alcohol. In recent times, the emergence of nanofluids (NFs) has opened avenues for rapid HT and the same is being intensively studied since last two decades. NF is a novel group of HT fluids prepared by suspending nanometer-sized materials (<100 nm) such as nanoparticles, nanofibers, nanotubes, nanowires, nanorods, nanosheets into conventional base fluids, leading to a phenomenal increase in thermal conductivity in comparison to microsuspensions or macrosuspensions. Some of the commonly reported nanometer-sized materials used for HT application include Al2O3, CuO, TiO2, carbon nanotubes (CNT), SiC, carbon coated Cu, Al, Au, and Fe nanoparticles. The baffling thermal characteristics of these novel fluids are not yet elucidated by existent theories of thermodynamics. An efficient design of NF-based process equipment for a quality end product is based on the selection, prediction, monitoring, and controlling of process parameters that would in turn rely on the thermal properties like specific heat and thermal conductivity of the NF. The exploration of HT mechanisms by developing appropriate models and design of compatible food processing equipment can 84give rise to a new generation HT media for efficient and enhanced energy transfer in the dairy and food industry. This chapter reviews application of NFs to enhance HT in dairy and food industries.