A Review Paper on Experimental Heat Transfer Enhancement using Nanofluids

Properties that mainly determine the thermal performance of a liquid for heat transfer applications are the thermal conductivity, viscosity, specific heat and density. Fluids such as air, water, ethylene glycol, and mineral oils are typically used as heat transfer media in applications such as power generation, chemical production, automobiles, air conditioning and refrigeration. However, their heat transfer capability is limited by their very low thermal conductivity. For enhancement of thermal conductivity of these fluids, much attention has been paid in the past decade to a new type of composite material i.e. nanofluids. Nanofluids are the suspensions of nanoparticles in base fluids. Nanoparticles have unique features different from conventional solids liquid mixtures in which mm or micrometer sized particles of metals and non-metals are dispersed. Due to their excellent characteristics nanofluids find wide applications in enhancing heat transfer. A nanoparticles suspension is considered as a three phase system including the solid phase (Nanoparticles), the liquid phase (fluid media), and the interfacial phase, which contributes significantly to the system properties because of their extremely high surface-to-volume ratio in nanofluids. The system engineering approach was applied to nanofluid design resulting in a critical assessment of various parameters in the multivariable nanofluid systems. Understanding the relative importance of nanofluid parameters for heat transfer allows engineering nanofluids with desired set of properties. This review provides an experimental review on the historical evolution of nanofluid concept, heat transfer enhancement of base fluid with nanoparticles and scope of applications of nanofluids.