Paper Title
Effect Of Multi-Wall Carbon Nanotubes On Flow Condensation Heat Transfer Of R-600a/Oil Mixture

Abstract
In the present work, the influence of multi-wall carbon nanotubes (MWCNTs) on flow condensation heat transfer of R-600a/oil mixture inside a horizontal smooth tube is investigated. The experimental conditions of this study include mass velocities from 140 to 328 kg/m2s, inlet vapor qualities from 0.11 to 0.78, heat fluxes from 10.08 to 26.88 kW/m2 and mass fractions of MWCNTs from 0.1 to 0.4wt%. For this aim, a well-equipped semi-refrigeration test-rig including pump, mass flow meter, pre heater, test condenser, by-pass and evaporator is designed, fabricated and installed in order to collect the experimental data on flow condensation heat transfer of refrigerant-nano-oil mixture. MWCNT-oil mixture is prepared using a two-step method and then the nano-oil is injected with a syringe into the pure refrigerant through the cycle. The results show that, the presence of MWCNTs at maximum nano concentration and mass velocity, causes maximum heat transfer coefficient enhancement of up to 67.30% relative to the coefficient of R-600a/oil mixture without nanoparticles. Keywordsó MWCNT; refrigerant; heat transfer; two-phase flow.