1420 KB45 KB199920252019Ghanbari, ShahinJavaherdeh, Kouroshletnik:65številka:9str. 503-514ISSN:0039-2480COBISSID_HOST:16827419URN:URN:NBN:SI:doc-JQG72L5LenZveza strojnih inženirjev in tehnikov Slovenije etc.Strojniški vestnikannular tubescevi kolobarjastega prerezafaktorji toplotne učinkovitostinanofluidinanofluidsnanoporous graphenesnanoporozni grafenipressure dropsthermal performance factorstlačni padecExperimental assessment of turbulence convective heat transfer and pressure drop in annuli using nanoporous graphene non-newtonian nanofluid|In the current research work, turbulence convective heat transfer coefficient enhancement and pressure drop of nanoporous graphene non-Newtonian nanofluid were investigated in an annular tube in the developing region. The nanofluid was prepared by using nanoporous graphene in different concentrations of 0.05 wt.%, 0.1 wt.%, and 0.2 wt.% in an aqueous solution of carboxyl methyl cellulose (CMC). All thermophysical and rheological characteristics were evaluated, and pseudo-plastic (shear-thinning) rheological behaviour was observed for all samples. The results revealed that adding 0.2 wt.% nanoporous graphene to the base fluid leads to 12.4 % and 39.4 % enhancement of thermal conductivity and heat transfer coefficient, respectively. This enhancement trend was almost linear for the concentrations lower than 0.1 wt.% after which the enhancement rate was reduced significantly. Moreover, the results showed that when 0.05 and 0.1 wt.% nanoporous graphene was adopted, the thermal performance factor (TPF) was increased by 8.7 % and 16.7 %, respectively, and doubling the nanoparticle concentration from 0.1 wt.% to 0.2 wt.% could not augment the TPF; however, considering the assessed pressure drop, it also decreased it by 2.5 %. The increase of the Reynolds number led to an increase in heat transfer coefficient of all samplesTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Ljubljani, Fakulteta za strojništvo