RT Journal Article ID 5de224e63fc9ca0b A1 Singh, Gurpreet A1 Dasaroju, Gangacharyulu A1 Bulasara, Vijaya Kumar T1 EXPERIMENTAL INVESTIGATION OF THE EFFECT OF HEAT TRANSFER AND PRESSURE DROP ON PERFORMANCE OF A FLAT TUBE BY USING WATER-BASED Al2O3 NANOFLUIDS JF International Journal of Energy for a Clean Environment JO IJECE YR 2018 FD 2018-04-05 VO 19 IS 1-2 SP 1 OP 17 K1 flat tube K1 convective heat transfer coefficient K1 pressure drop K1 nanofluids AB The aim of the present study was to experimentally investigate the heat transfer and pressure drop characteristics in a vertical flat tube with nanofluids. Aluminum oxide nanoparticles with average size of 20 nm were used to prepare the nanofluids of different volume fractions (0.1%, 0.2%, 0.3%, and 0.4%) without the use of any surfactant. The thermophysical properties, i.e., thermal conductivity, viscosity, and density over a wide range of temperatures (30°C–65°C) were measured experimentally. The thermal conductivity, viscosity, and density increased with the concentration of nanofluids. The heat transfer coefficient and pressure drop were estimated for different inlet temperatures of nanofluids (45°C–85°C) for the Reynolds number range 10,000–30,000, while the air velocity was kept constant at 0.55 m/s. During the experimentation, it was observed that the heat transfer coefficient and pressure drop increased with the Reynolds number and particle volume fraction. It was also observed that the heat transfer coefficient increased with the fluid inlet temperature because the viscosity and density of the fluid decreased at higher temperatures, while the pressure drop decreases slightly with increase in the fluid inlet temperatures. The heat transfer coefficient increased when the particle volume fraction was increased from 0.1% to 0.4% and maximum heat transfer coefficient was enhanced by 14% with the use of 0.4% v/v concentration of nanofluids at Reynolds number 30,000 and inlet temperature 85°C. The pressure drop ratio was 1.4 for 0.4% v/v concentrations of Al2O3 nanoparticles. PB Begell House LK https://www.dl.begellhouse.com/journals/6d18a859536a7b02,71bb65664c992be8,5de224e63fc9ca0b.html