Experimental study of the effect of the helical ribs in a spirally coiled tube on the friction factor and the Nusselt number of a nanofluid flow in it

The effect of the centrifugal force arising in a spirally coiled tube with helical ribs on the heat transfer in the fluid flow in it was investigated. It is shown that, due to this force, the rate of heat transfer in the fluid flow in a spirally coiled tube with helical ribs is larger than that in an analogous tube with no ribs. It was established that, in the case where nanoparticles are added to the base fluid flowing in a spirally coiled tube with helical ribs, its transport properties change, with the result that the Nusselt number of the fluid flow increases. Moreover, an increase in the nanofluid concentration leads to an increase in the rate of heat transfer in the fluid flow in the tube depending on the direction of its helical ribs, and the friction factor of the fluid flow in the tube insignificantly increases in this case (authors)