Studi Eksperimental Perpindahan Kalor Konveksi Fluida Nano Al2o3/Ethylene Glycol Pada Circular Tube Di Bawah Kondisi Fluks Kalor Konstan

Abstract

Abstract : This research was conducted to examine the thermal conductivity and heat transfer characteristic of Al203/ethylene glycol nanofluid on a circular tube heat exchanger under constant heat flux conditions. Al2O3 nanoparticles were dispersed in ethylene glycol as base fluid at three different particles concentration of 0,2%, 0,5%, and 1,0% w/v, respectively. A straight horizontal stainless-steel tube of 1,2 m length, 0,005 m inner diameter and 0,0063 m outer diameter was used as a test section. A nickelin coil heater was connected to an AC regulated power supply to obtain constant wall heat-flux boundary condition. The flow rates were adjusted to obtain the Reynolds number specification from 350 to 700. The result shows that the effective thermal conductivity increases from its base fluid. The highest enhancement of thermal conductivity of the observed nanofluids is 5,81% for nanoparticles concentration of 1,0% w/v. For the same Reynolds number, heat transfer increases with the increase of the Nusselt number from base fluid to nanofluids at x/Di = 200 with the highest value of 37,62% for 1,0% w/v. At the Reynolds number variation, the highest Nusselt number enhancement at x/Di = 200 reaches 45,52% from Reynolds number 350 to 630 concentration of 1,0% w/v.

Keywords : Heat transfer coefficient, Nanofluids, Particle concentrations, Thermal conductivity, Al2O3 nano particle