Energy and exergy analysis of concentered mini tube heat exchanger using nanofluid

Mini-channel heat exchangers are used in the heating and cooling processes of various electronic devices. Heat transfer is very important for the safe operation of electronic equipment. It has been determined that mini channels provide high heat transfer compared to large channel heat exchangers due to the volume and surface effect factor. One of the methods used to increase heating and cooling efficiency is by adding nano-sized particles with high thermal conductivity to basic heat fluids such as water, oil and ethanol. Since the thermal conductivity of a solid nanoparticle is much better than any basic fluid, these particles form a suspension with the fluid, making it a fluid with high thermal conductivity. In this thesis, a concentric mini-channel heat exchanger test zone and experiment set were designed. The accuracy of the system was confirmed by comparing this designed experimental setup with the Nusselt number and friction factor correlations available in the literature for the case where water is used as the working fluid. Then, energy and exergy analysis were carried out by preparing Multi-walled carbon nanotube (MWCNT) nanofluid, which was prepared at three different volumetric concentrations (0.1-0.2-0.3) with the validated experimental set. The ε-NTU method was used in the thesis. Efficiency (ε), NTU and dimensionless exergy (e) values were calculated in the range of 5 different Reynolds values (5000-25000) under turbulent flow conditions for different water and nanofluids prepared at different volumetric concentrations. The use of nanofluid as the working fluid increased the ε and NTU values, while decreasing the dimensionless exergy value.