Investigation of Potential Advantages of Nanofluids in Convective Heat Transfer

Author

Adam Wayne Sims, Southern Illinois University CarbondaleFollow

Date of Award

8-1-2012

Degree Name

Master of Science

Department

Mechanical Engineering

First Advisor

Mondal, Kanchan

Abstract

The research aimed at developing an experimental apparatus that was employed to estimate the convective heat transfer rate of nanofluids during cooling. The project started with the design and fabrication of the previously mentioned apparatus and continued with the evaluation of its effectiveness to test several different variables such as nanoparticle concentration and Reynolds Number. In all the experiments conducted, the cooling was achieved by natural convection with the ambient air. Along with the apparatus, a spreadsheet based data analysis algorithm was developed to analyze the data acquisition system. The research also attempted to model the convective heat transfer coefficient of nanofluids based as a function of the Reynolds Number and the nanofluid concentration. Even though some conclusions could be made, there were issues with the quality of data obtained from the experiment. Due to the low temperature difference between the ambient air and the nanofluid and the short length of the tube, the temperature difference was small relative to the error associated with each sensor. An interesting observation during this investigation is a lack of dependency of the Nusselt Number on the Reynolds Number which is contrary to much of the reported literature. The data did, however, show a functional relationship between the Nusselt Number and the volume fraction of nanoparticles where Nu=aφ0.25. Many methods of reducing the errors were determined such as the addition of an outer controlled environment that would increase the temperature difference between the nanofluid and the outer wall of the tubes in order to enhance the rates of heat transfer and in turn increase the temperature difference between the sensor locations along the fluid flow. With the employment of these methods on the current apparatus, it could be a very successful method of quickly and easily determining convective heat transfer coefficients especially with the use of the algorithm imbedded in the spreadsheet to determine important factors.