Performance index improvement of a double-pipe cooler with MgO/water-ethylene glycol (50:50) nano-suspension
H. Arya a,*, M.M. Sarafraz b, O. Pourmehran b, M. Arjomandi b
a. Centre for Energy Resource Engineering, Technical University of Denmark, Denmark
b. School of Mechanical Engineering, University of Adelaide, South Australia, Australia
Abstract: A series of tests was conducted to unlock the potential application of MgO/water-EG (ethylene glycol) nanofluids (NF) in a double-pipe heat exchanger (HEX). The overall heat transfer coefficient (HTC), the inlet temperature of the working fluid, the fluid pressure drop (FPD), friction factor (FF) and the hydraulic performance index of the NF within the HEX were experimentally measured. Fouling of nanoparticles (NPs) within the Hex was also studied and modelled using asymptotic particulate fouling model. Results showed that MgO NPs can enhance the HTC by 39% at Re=10500 and wt.%=0.3 in the turbulent regime. Also, the presence of MgO NPs augmented the FF and the FPD values. The former was enhanced 33.8%, while the latter was augmented by 37% both at wt.%=0.3 and at Reynolds number=10500. Results also revealed that the formation of porous particulate fouling layer on the internal wall of the inner tube creates a fouling thermal resistance which changes asymptotically with time. Overall, MgO/water-ethylene glycol shows a great potential to be used as a coolant within a HEX.
Keywords: Forced convective heat transfer; Particulate fouling; Heat exchanger; Fouling; Nanofluid