In the present study, the heat transfer and flow of water/FMWCNT (functionalized multi-walled carbon nanotube) nanofluids over a flat plate was investigated using a finite volume method. Simulations were performed for velocity ranging from 0.17 mm/s to 1.7 mm/s under laminar regime and nanotube concentrations up to 0.2%. The 2-D governing equations were solved using an in-house FORTRAN code. For a specific free stream velocity, the presented results showed that increasing the weight percentage of nanotubes increased the Nusselt number. However, an increase in the solid weight percentage had a negligible effect on the wall shear stress. The results also indicated that increasing the free stream velocity for all cases leads to thinner boundary layer thickness, while increasing the FMWCNT concentration causes an increase in the boundary layer thickness.
a b s t r a c tNowadays, nanofluids are being considered as an efficient heat transfer fluid in various thermal applications. Refrigerant-based nanofluids, termed as ''nanorefrigerants'', have the potential to improve the heat transfer performances of refrigeration and air-conditioning systems. This study analyzed the thermophysical properties and their effects on the coefficient of performance (COP) resulted by addition of 5 vol.% Al 2 O 3 nanoparticles into R-134a refrigerant at temperatures of 283-308 K. The analysis has been done for a uniform mass flux through a horizontal smooth tube using established correlations.The results indicate that the thermal conductivity, dynamic viscosity, and density of Al 2 O 3 /R-134a nanorefrigerant increased about 28.58%, 13.68%, and 11%, respectively compared to the base refrigerant (R-134a) for the same temperature. On the other hand, specific heat of nanorefrigerant is slightly lower than that of R-134a. Moreover, Al 2 O 3 /R-134a nanorefrigerant shows the highest COP of 15%, 3.2%, and 2.6% for thermal conductivity, density, and specific heat, respectively compared to R-134a refrigerant. Therefore, application of nanoparticles in refrigeration and air-conditioning systems is promising to improve the performances of the systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.