Effect of Al2O3 / Water Nanofluid Concentration on Heat Transfer and Fluid Flow Characteristics in U Type Flow Cross Flow Compact Heat Exchanger

Abstract

Heat transfer and fluid flow characteristics of U type flow cross flow compact heat exchanger was measured experimentally under laminar flow conditions. Al2O3 nanoparticles were used to prepare nanofluids at 0.1% by vol. and 0.2% by vol. concentration in distilled water. Flow rate in heat exchanger was varied from 25 liters / hour to 40 liters / hour. Air makes cross flow through the tubes, whose flow rate was varied from 241.92 m3 / hour to 728.35 m3 / hour. Cross flow heat exchanger consisted of 28 flat brass tubes in two rows with copper multi louvered fins. In heat exchanger, working fluid entered in tubes at inlet temperature values of 45⁰C, 50⁰C, and 55⁰C. Experimental results showed that increase in nanofluid flow rate and concentration with temperature, heat transfer coefficient was increased by 16.38% to 18.51%. Effectiveness of cross flow heat exchanger was increased from 68.52% to 72.56%, and 74.21% for 0.1% by vol., and 0.2% vol. concentration respectively. Friction factor value increased to 11.11% and 25.56% at 45⁰C temperature for 0.1% by vol., and 0.2% vol. concentration respectively. But as the flow rate of fluid at tubes side increased the value of friction factor decreased by 60%.