Numerical investigations on heat transfer performance of hybrid nonofluids in double tube head exchanger

Abstract

Heat exchanger is used in industries to transfer heat from one medium to newlineanother which are at different temperatures. It is used in various applications newlinesuch as heating and cooling buildings, auto-mobile industry, marine unit, food newlineprocessing unit etc. It is considered as one of the important components in newlineindustries. Based on applications, heat exchangers are categorized as (1) doubletube heat exchanger (2) shell and tube heat exchanger (3) plate heat exchanger (4) finned tube heat exchanger etc. In general, the conventional fluids like water, ethylene glycol, and bio-fluids are used as a coolant. Ultra-high cooling newlineperformance (of heat exchanger) is the pre-requisite of all industries. But these newlinefluids provide lower thermal conductivity which is the foremost limitation to newlineencourage the ultra-high cooling performance (of heat exchanger) in industries. newlineFor example, in liquids, thermal conductivity is dependent on the diffusion effect newlinebetween molecules. By increasing the temperature, random motion (Brownian newlineeffect) between molecules are increased and so it reduces the heat transfer newline(convection mode) process. Therefore the thermal performance of the heat newlineexchanger will be lower. There is an alternate route to improve the heat transfer newlineperformance (HTP) of heat exchanger. The addition of nanosized (1-100 nm) newlineparticles in the conventional fluid can increase the thermal conductivity of the newlineconventional fluid and the resultant fluid is known as nanofluid. In general, newlinemetal, metal oxide nanoparticles and based on geometry the elongated structure newlinematerial (Carbon nanotubes) are used in nanofluids (as a dispersed material). There are extensive range of nanoparticles that have been employed so far, these include Cu, Ag, Al, Au, Fe and Co (metals), CuO, Al2O3, Fe3O4, TiO2 and ZnO (metal oxide) SWCNTs, MWCNTs, and CNTs (elongated structures). newline newline