A comparative investigation on heat transfer performance of novel nanoaerosols in pipe flow: Experimental results

Abstract

This paper describes the experimental analysis of aerosol heat transfer coefficient (AHTC), pressure drop, and friction factor of SiO2, TiO2, and MgO nanoaerosol in the pipe flow with the volumetric flow rate of 30 lpm, 40 lpm, and 50 lpm. The SiO2, TiO2, and MgO nanoparticles are characterized by using the field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) analysis. The SiO2, TiO2, and MgO nanoparticles are dispersed in the air at the particle volume concentrations of 0.5 %, 1.0 %, and 5.0 %, respectively. The thermo-physical characteristics of nanoaerosols are determined using empirical correlations. The variation in temperature, pressure, and flow rates are measured by using the thermocouples, pressure gauges, and flow meters installed in the experimental setup. The temperature readings are recorded by using the data acquisition system. The experimental results indicate the enhancement of forced convective AHTC with the increase in the nanoparticle volume concentration and the volumetric flow rate of the nanoaerosol. At volumetric flow rates of 30 lpm, 40 lpm, and 50 lpm, respectively, increasing the particle volume fraction from 0.5 % to 5.0 % improves the average heat transfer coefficient by 92 %, 84 %, and 91 % for SiO2 nanoaerosol, 72 %, 50 %, and 37 % for TiO2 nanoaerosol, and 50 %, 67 %, and 72 % for MgO nanoaerosol. The pressure drop of the nanoaerosol increases by 2, 2.33, and 3 times, respectively, and the friction factor decreases by 27.99, 15.99, and 11.1 times for SiO2, TiO2, and MgO nanoaerosol by increasing the flow rate from 30 lpm to 50 lpm. For the SiO2, TiO2, and MgO nanoaerosols, increasing the particle volume concentration from 0.5 % to 5.0 % increases the pressure drop by 6, 7.66, and 10 times, respectively, and the friction factor by 32.03, 19.08, and 5.67 times. By considering all of these factors, it is concluded that the performance evaluation criteria are lowest for 0.5 % TiO2 and highest for 5.0 % MgO. The significant finding of this research is that the AHTC increases with the increase in the particle volume concentration and volumetric flow rate. Whereas, the friction factor decreases with the increase in the volumetric flow rates.