Experimental Investigation of Shell-and-Tube‏ ‏Heat Exchanger ‎Performance using 〖Al〗_2 O_3-Water Nanofluid

Abstract

This paper presents a comparative study of thermal properties of a shell and tube type heat exchanger filled with an Al2O3-water nanofluid with the one filled by pure water. It was decided to use Aluminum oxide (Al2O3) because it was chemically stable, commercially available and found to be effective in improving thermal conductivity without extreme hydraulic penalties. The experiments were carried out for a range of Reynolds numbers between [12,600 to 63,300] and at a concentration of 30g per 10L of base fluid. The effectiveness-NTU (ε-NTU) approach was used for data reduction. The results indicate that the counter-flow design produced a large positive effect, increasing the effectiveness by 17-19%, and a reduction in the fluid temperature at the high end by about 5°C. The parallel-flow configuration enhanced the performance as well, with an approximate 16% more effectiveness gain. The improvement in thermal conductivity was achieved with the addition of nanoparticles; however, the increase in the fluid viscosity means that extra pumping power may be necessary. In conclusion, low concentration Al2O3 nanofluids are potentially useful to enhance the thermal efficiency of the heat transfer processes used in industry, but hydraulic losses must be adequately reduced.