Mechanical agitation and adding dispersants or surfactants can enhance the nanofluid suspension performance and durability of the most commonly used methods. Because mechanical agitation
has difficulty achieving long-term stable suspensions, adding a dispersant or surfactant is often necessary to achieve long-term stable suspension. Commonly used dispersants contain a nitric/sulfuric
acid mixture, potassium hydroxide, and a wide range of dispersants such as sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), hexadecyl trimethyl ammonium bromide
(CATB), gum Arabic (GA), and chitosan (CH)[9,10,14–18]. Although adding dispersants to promote dispersion of nanomaterials in the base fluid can maintain a good suspension performance over a long
period, it may reduce the thermal conductivity of the nanofluid because of the lower thermal conductivity of the dispersants