Heat transfer enhancement using nanofluids in a parallel flow double pipe heat exchanger

Abstract

Heat Exchanger are among those engineered designs in which is widely used among many industries. Thus, in this research a double pipe heat exchanger is numerically and mathematically investigated, in which the various characteristics of heat transfer are evaluated. The experiment is mainly conducted using nanofluids, hence why the characteristics of the nanofluid itself is also considered a variable. Copper oxide, and aluminum oxide are the two nanoparticles used to conduct the simulation. Each of these are tested using different diameter sizes, as well as different concentrations dissolved in water. The Reynolds Number is also floating between 5000 and 20,000. The aim is to determine the effect of volume friction and diameter of nanoparticle on heat transfer and fluid flow, via the use of a double pipe heat exchanger. This is done by numerically investigating the heat exchanger by using ANSYS software system, which is able to simulate the results as well as the various characteristics involved. The results indicated that aluminum oxide is superior to copper oxide in terms of heat transfer enhancement. They also indicated that as the diameter of the nanoparticles increased, the heat transfer effectiveness decreased. The most optimal solution presented itself as the lowest diameter, and highest concentration in relation to the base fluid. When compared to the conventional fluid (water) the heat transfer coefficient was improved by 94.7% on average, and the Nusselt Number was also improved by 44.5%. Furthermore, there was a 45.37% improvement observed when comparing the best obtained results to an existing literature that uses a double pipe heat exchanger, and a 61.3% improvement for when the results are compared to an existing baseline straight tube heat exchanger. The results also indicated that there are minor differences between parallel and counter-flow regimes in the double pipe heat exchanger, with the counter-flow performing better at higher Reynolds numbers, while the parallel performs better when under 10,000 Reynolds number. This indicates that the proposed solution is practical and better to use versus water.