10.2021.286.299

Improving Thermal Performance of Heat Exchangers Using Compatible Nanoparticles Fluids

Author(s):

Noor A. Hasan, Hussein Yousif Mahmood

Affiliation(s):

Mechanical Engineering Department*, University of Baghdad, Baghdad, Iraq

Corresponding Author Email: nhasan1209@coeng.uobaghdad.edu.iq

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In the present work, the possibility of improvement of heat efficiency of double-tube counter-flow heat exchanger has been investigated experimentally. By using a sub-scale model of a shell – tube heat exchanger with two types of Nano-fluids; single Nano-fluids, hybrid Nano fluids [α-Al2O3 (20nm)/water Nano fluid, CuO (50nm)/water Nano fluid, and α-Al2O3-CuO/water hybrid Nano fluid and a mixing ratio (50:50)], as cooling fluids at two volumetric concentrations (0.1% and 0.5 %) for each working fluid. The Nano fluids and water flow inside the cold internal cycle with constant inlet temperature (29̊C), flow rates (100, 150, 200, 250) l/h and transitional and turbulent flow conditions within a range Re (3207 to 8070), Hot water flows into the hot external cycle with an inlet temperature that constant (70̊C) and at a steady volumetric flow rate (150 l/h) and within the range Re (2941 to 3094). The experimental results showed that the maximum enhancement in the heat transfer coefficient and thermal conductivity at Al2O3-CuO/water hybrid Nano fluid and concentration Ø=0.5% (1.1766 and 0.6391), respectively. And the maximum percent enhancement in heat transfer rate is (72.87%) at Al2O3-CuO/water hybrid Nano fluid and concentration (Ø=0.5%). The results obtained in this work indicated that the good effects of employing a hybrid Nano fluid were superior to using a single-type Nano fluid. It also showed that the rate of heat transfer increases with the increase in the concentration of nanoparticles. In the same context, the effect of the type of nanoparticles on the rate of heat transfer was observed it had a higher heat transfer rate α-Al2O3 (20nm)/water Nano fluid than a heat transfer rate CuO (50nm)/water Nano fluid. The highest effectiveness of the heat exchanger is (0.29188) when using Al2O3-CuO/water hybrid Nano fluid at (Ø=0.5%). The highest pressure drop in the inner tube is (∆P=285.299 Pa) at CuO/water Nano fluid (Ø=0.5%) at a flow rate (250 l/h) and Re (8×103).