Experimental study on flow condensation pressure drop of R123-MWCNTs nanorefrigerant

Abstract

In-tube flow condensation plays a vital role in heat exchangers. This study investigates the frictional pressure drop (FPD) and penalty factor (PF) of R123-MWCNTs nanoblend condensing within a horizontal, smooth pipe. MWCNTs, due to their superior thermal conductivity, are appended with base R123 through ultrasonication. The test facility has been designed and fabricated to conduct the proposed experiments with varying parameters and their ranges, such as the mass velocity of about 200−500kg/m2s, a refrigerant vapour quality of 0.02−0.9, saturating temperatures of about 35.3 and 40.9∘C, and a volume percentage of MWCNTs of about 0.01 to 0.1%. The experiments are performed at steady-state conditions. The studies reveal that the nanorefrigerant has a larger FPD than the conventional refrigerant of about 17−50%, 19−52%, and 22−53% at ϕ=0.01−0.1%, respectively, for mass velocity from 200−500kg/m2s, and that this drop increases with MWCNTs concentration. As the saturated temperature rises, the FPD reduces for pure and nano-mixtures of about 6–9%, 7–4%, 7–8%, and 7–5%, respectively, at sustained mass velocity (200−500kg/m2s) and the refrigerant vapour quality (0.02−0.9). The penalty factor lowers as the refrigerant mass velocity and the vapour quality increase. The accuracy of the present work has been estimated by comparing the experimental FPD with the predicted FPD. The MAPE and MPE are evaluated using the available correlations, and the results show an acceptable agreement of about 12.6, 11.7, 12.7%, and 29% and -5.7%, -5.4%, -5.7%, and -12%, respectively, by Lockhart (1949), Yan and Lin (1999), Huang et al. (2010) and Haraguchi et al. (1994), respectively.