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We experimentally investigated the fully developed laminar convective heat transfer and friction factor characteristics of different volume concentrations of Al2O3 nanofluid in a plain tube and fitted with different twist ratios of twisted tape inserts. Experiments were conducted with water and nanofluid in the range of 700 Re2200, particle volume concentration of 0.5%, and twisted tape twist ratios of 0H / D15. The nanofluid heat transfer coefficient is high compared to water and further heat transfer enhancement is observed with twisted tape inserts. The pressure drop increases slightly with the inserts, but is comparatively negligible. A generalized regression equation is developed based on the experimental data for the estimation of the Nusselt number and friction factor for water and nanofluid in a plain tube and with twisted tape inserts.

The main aim of the present investigation is to study the heat transfer behaviour of nanofluids in a circular tube under laminar flow condition by using commercially available FLUENT 6.0 software. In this analysis Al2 O2, CuO and TiO2 nanofluids are considered. Thermo-physical properties of the nanofluids (thermal conductivity, density, viscosity and specific heat) are obtained from the literature. Constant heat flux boundary condition is applied for the estimation of heat transfer coefficient of nanofluids inside a tube. All the investigations of nanofluids are carried out in the volume concentrations ranging from 0.3-2.0% and at the same Reynolds number. The values obtained from CFD analysis of nanofluids are compared with the values of water.

This paper describes the wear mechanism and tool life when machining Hastelloy C-22HS with coated carbide. The experiment was conducted using four different cutting tool materials under wet condition – namely, Physical Vapor Deposition (PVD) coated with TiAlN; TiN/TiCN/TiN; Chemical Vapor Deposition (CVD) coated with TiN/TiCN/Al2O3; and TiN/TiCN/TiN – to study the tool behavior, in terms of wear and tool life machining of Hastelloy C-22HS. Tool failure modes and wear mechanism were examined at various cutting parameters. Flank wear, chipping, notching, plastic lowering at cutting edge, catastrophic and wear at nose were found to be the predominant tool failure for the four types of cutting tools, especially with CVD tools. Attrition/adhesion, oxidation and built-up edge (BUE) are the wear mechanisms observed in all cutting tools. The results obtained indicated that PVD cutting tools performed better than CVD cutting tools, in terms of tool life with current parameters.