Experimental investigation of nanofluid use in mini-channel shell and tube heat exchanger

Reducing channel sizes from macro to mini is a passive heat transfer enhancement method. Using this method in shell and tube heat exchangers will reduce costs by saving material, volume, and energy. More compactness results in a more intense heat transfer with a smaller volume and a smaller heat transfer area. It also reduces the amount of working fluid. In addition, the performance of heat exchangers can be enhanced by adding solid particles to the working fluids through another passive heat transfer enhancement method. It is believed that heat transfer can be further enhanced by adding nanoparticles to pure working fluids (such as water, oil, and ethylene glycol) and obtaining nanofluids by changing their thermophysical properties. This study experimentally investigated heat transfer and pressure drop on the tube side of a single-pass mini-channel shell and tube heat exchanger designed according to the Kern method. The experiments were carried out under counterflow conditions from hot fluid (hot water at 40°C) at the shell side to cold fluid (cold water and nanofluids at 20°C) at the tube side. The heat transfer and pressure drop performances of tube-side water and Al2O3-water nanofluids prepared in six different volumetric concentrations (0.02%, 0.1%, 0.2%, 0.4%, 0.6% and 0.8%) were investigated under transitional flow and turbulent flow conditions (1900