Interface chemistry and particle size distribution effects on the specific heat capacity of nanofluids

Enhancing the specific heat capacity of nanofluids has long been reported but remains poorly understood, with inconsistent experimental evidence and a lack of predictive models. Here we introduce a simple yet physically grounded framework in which deviations from ideal mixture behaviour arise from an interface heat capacity term proportional to the nanoparticle surface area. Using extensive molecular dynamics simulations of metal–organic nanofluids, we show that the interface heat capacity is strongly dependent on the chemistry of the solid–liquid interface, larger for group (10) metals (Ni, Pd, Pt) (on the order of 10 -6 to 10 -5 J K −1 m −2 ) than for group (11) metals (Cu, Ag, Au) (on the order of 10 -7 to 10 -6 J K −1 m −2 ), and decreases sharply with temperature. Incorporating particle morphology and size distributions, the model predicts that nanofluids with high-aspect-ratio particles ( i.e. , 2D nanomaterials) and narrow size dispersity can exhibit moderate enhancements in specific heat, while spherical nanoparticles largely follow the ideal mixture limit. These results provide design guidelines for tailoring nanofluids with improved thermal storage and transfer performance.