Master’s thesis at the Engineering Technical College, Kirkuk, presented by the student Firas Faisal Qaderun (Evaluation of multiple fillings in a circular tube using nanofluids)
The thesis dealt with the following:
A study on evaluation of forced convection performance of pure water and nanofluids flowing through a horizontal circular tube heated with constant convection flow and filled with a numerically saturated porous medium, using simulation software ANSYS FLUENT. The porous medium consists of stainless steel balls with diameters of 1 and 3 mm. Two types of nanofluids CuO-water and TiO2-water with three different volume concentrations (0.1, 0.3, and 0.5%) were used instead of pure water in the simulation process, to monitor the heat transfer behavior with Reynolds numbers and nanoparticle concentrations. The numerical results obtained for both cases were compared with each other. Then those results were compared with the experimental results of previous research, which successfully validated the numerical model. The results showed that the ANSYS FLUENT software can produce reliable and simultaneous solutions of porous media with nanofluids in heat transfer problems, provided that the boundary conditions and all parameters are specified correctly and accurately.
The thesis aimed to:
Numerical simulation to evaluate thermal performance without the need for an expensive model and tedious experimental measurements or reducing the number of experiments and thus reducing the total cost. Increase the efficiency of heat exchangers and reduce their size in order to reduce their energy consumption. Study the effect of the flow velocity (Reynolds number) of the working fluid in a porous medium, the porosity of the volumetric concentrations of nanofluids, and the rate of heat flow on the heat transfer coefficient, pressure drop, friction factor, and average Nusselt number.
The researcher concluded:
The results showed an increase in the heat transfer coefficient and the Nusselt number with an increase in the Reynolds number and heat flow, as well as a decrease in the porosity due to the reduction in the voids between the spheres, which led to an increase in turbulence. The maximum Nusselt number reached 314.97 for a sphere with a diameter of 1 mm, at heat flux 12500 W/m2 and Reynolds number 6500. The results indicated that the heat transfer coefficient and average Nusselt number increased with increasing nanofluid volumetric concentration and Reynolds number. The heat transfer coefficient of TiO2-water and CuO-water nanofluids increased by 67% and 78%, and the Nusselt number by 89% and 78%, respectively when the Reynolds number was increased from (4800 to 6500) in the turbulent flow regime and at a volumetric concentration of 0.5%. The highest Nusselt number reached 365.23 for CuO-water nanofluid with a volume concentration of 0.5% and the Reynolds number 6500.
The discussion committee consisted of the following gentlemen:
1- Prof. Dr. Sabah Tariq Ahmed, Chairman
2- Assistant Professor Badran Muhammad Salem, member
3_ The teacher, Dr. Hussein Haider Muhammad Ali, a member
4- Prof. Dr. Adnan Muhammad Hussein, member and first supervisor
5- Assistant Professor Dr. Suad Hassan Danuk, member and second supervisor