Optimization of the double pipe heat exchangers having nanofluid

Diameter of the heat exchanger pipes has a strong effect on the flow characteristics and the investment, operation, and overall cost. It is known that fin dimensions affect annulus hydraulic diameters. The addition of fins to the design increases the heat transfer area and thus enhances the heat duty compared to bare design where both designs cover same volume. Special attention should be given to calculation of fin dimensions of pipes for given flow rates and heat exchanger dimension. With in the scope of this thesis, determination of proper fin geometries, optimum operation condition with cost analysis for current heat exchanger have been performed to be ready for manufacturing and use in real life. In addition to these, effect of the type of the working fluids and fouled and clean cases are investigated for the total heat transfer enhancement in parallel with performance, lifetime, and cost issues. Investigation of detailed analysis of a double-pipe heat exchanger model have been presented for engine oil and its nanofluid mixtures with Ti, TiO2, Cu, CuO, Al, Al2O3 nanoparticles, carbon nanotube (MWCNT) and graphene nano sheet having a constant particle concentration in liquid phase flowing in annulus side in case of its unfinned and the finned design, respectively, and sea water is flowing in the tube side in the meantime. Pressure drop and pumping power values increase with increasing fin number and decreasing with cleanliness factor (CF) whereas total tube number decreases with increasing fin number. It is found that different types of nanofluids affect the cost and optimum annulus side velocity differently. Comprehensive outputs are performed by plotting the findings in figures such as alteration of Reynolds of number with cleanliness factor, heat transfer coefficient, and pressure drop, also friction factor with mass flow rate, and cost values with annulus side velocities. Finally, physical appearance of the trend lines in these figures have been achieved as expected.