Laminar Natural Convection Heat Transfer From Isothermal Cylinders With Active Ends

Abstract

Calculation of free convection heat transfer from isothermal bodies of different shapes is of fundamental importance in science and engineering. In the present study, a new analytical model is developed to calculate laminar natural convection heat transfer from finite isothermal cylinders of arbitrary aspect ratio and orientation (vertical, horizontal, and inclined) with active ends in fluids of any Prandtl number. This method is based on the new concept of Dynamic Body Gravity Function. Also, a new dimensionless parameter called Body Fluid Function is introduced and applied in this method. Results of this dynamic model are presented for six different circular cylinders and compared with the available experimental data. Excellent agreement is found between the developed model and experimental results in a wide range of Rayleigh number for all cylinders discussed. This shows that the present method is a powerful tool for modeling laminar natural convection from isothermal bodies.

Acknowledgments

Mohammad Eslami is a Ph.D. student in mechanical engineering at Shiraz University, Shiraz, Iran. He worked on analytical modeling of natural convection heat transfer for his master's thesis and received his M.S. at Shiraz University in June 2008. His research interests have included convection and conduction heat transfer, numerical modeling of heat and fluid flow, electrokinetic flow in microchannels, and solar energy measurements and applications.

Khosrow Jafarpur is an associate professor of mechanical engineering at Shiraz University, Shiraz, Iran. He received his Ph.D. at the University of Waterloo, Canada, in 1992 and joined Shiraz University in the same year. His research includes free convection heat transfer, solar energy measurement, and solar stills, as well as heat transfer (and optimization) in welding, porous media, and nanosystems. He is the author or co-author of about 70 papers on these topics.