## THERMAL SCIENCE

International Scientific Journal

### Thermal Science - Online First

online first only
### Experimental study of the effects of a vertical channel on the natural convection of a horizontal cylinder

**ABSTRACT**

In this study, the natural convective flow and heat transfer from a hot horizontal cylinder surrounded by two vertical plates with a negligible thickness was experimentally investigated. These plates act as a channel so that the natural convective flow of the hot cylinder passes through this channel. The flow field was visualized using PIV technique to investigate the effect of changing the width of the channel and the height of the water free surface on the flow behavior. In each case, by changing the mentioned geometric parameters, flow velocity at the top of the cylinder, temperature of the cylinder surface, volume flow rate of the channel, the structure and location of vortices, and flow pattern inside the channel were studied. The results show that the flow is appropriately formed around the cylinder and inside the channel at a ratio of water free surface height above the channel to the cylinder diameter equal to 2, and a ratio of the channel width to the cylinder diameter equal to 2. Also, the cylinder Nusselt number was increased for the channel with a width ratio of 2, relative to the case without channel around the cylinder.

PAPER SUBMITTED: 2019-06-30

PAPER REVISED: 1970-01-01

PAPER ACCEPTED: 2020-02-24

PUBLISHED ONLINE: 2020-03-08

- Nakamura, H. and Asako, Y., "Laminar Free Convection from a Horizontal Cylinder with Uniform Cross Section of Arbitrary Shape," Bulletin of JSME, vol. 21, pp. 471-478, 1978.
- Haldar, S. C., "Laminar Free Convection Around a Horizontal Cylinder with External Longitudinal Fins," Heat Transfer Engineering, vol. 25, pp. 45-53, 2004.
- Kumar-De, A. and Dalal, A., "A Numerical Study of Natural Convection around a Square, Horizontal, Heated Cylinder Placed in an Enclosure," International Journal of Heat and Mass Transfer, vol. 49, pp. 4608-4623, 2006.
- Huynh, P., "Cooling By Free Convection at High Rayleigh Number of Cylinders Positioned Above a Plane," in 16th Australasian Fluid Mechanics Conference, Australia, 2007, pp. 654-658.
- Saha, S., Saha ,G., and Quamrul-Islam, M., "Natural Convection in Square Enclosure with Adiabatic Cylinder at Center and Discrete Bottom Heating," International University Journal of Science and Technology, vol. 3, pp. 29-36, 2008.
- Yu, Z.-T., Xu, X., Hu, Y.-C., Fan ,L.-W., and Cen, K.-F., "Transient natural convective heat transfer from a heated triangular cylinder to its air-filled coaxial cylindrical enclosure," International Journal of Heat and Mass Transfer, vol. 53, pp. 4296-4303, 2010.
- Yu, Z. T., Xu, X., Hu, Y. C., Fan, L. W., and Cen, K. F., "Unsteady Natural Convection Heat Transfer from a Heated Horizontal Circular Cylinder to Its Air-Filled Coaxial Triangular Enclosure," International Journal of Heat and Mass Transfer, vol. 54, pp. 1563-1571, 2011.
- Karimi, F., Xu, H. T., Wang, Z., Yang, M., and Zhang, Y., "Numerical Simulation of Unsteady Natural Convection from Heated Horizontal Circular Cylinders in a Square Enclosure," Numerical Heat Transfer, Part A: Applications, vol. 65, pp. 715-731, 2014.
- Rabani, R. and Talebi, F., "Free Convection from a Partially Heated Circular Cylinder inside a Square Enclosure," Progress in Computational Fluid Dynamics, an International Journal, vol. 15, pp. 372-387, 2015.
- Ashjaee, M., Yousefi, T., and Amiri, M" ,.Free Convection Heat Transfer from a Confined Horizontal Elliptic Cylinder," Heat Transfer Engineering, vol. 27, pp. 116-124, 2006.
- Ashjaee, M., Amiri, M., Baghapour, B., and Yousefi, T., "An Empirical Correlation for Natural Convection from Confined Elliptic Tube," Experimental Heat Transfer, vol. 20, pp. 213-228, 2007.
- Ashjaee, M., Yazdani, S., and Yousefi, T., "Experimental Investigation on Free Convection from a Horizontal Cylinder Located above an Adiabatic Surface," presented at the Fourth International Conference on Thermal Engineering: Theory and Applications, Abu Dhabi, UAE, 2009.
- Karami, A., Yousefi, T., Rezaei, E., and Amiri, A., "Modeling of the Free Convection Heat Transfer From an Isothermal Horizontal Cylinder in a Vertical Channel Via the Fuzzy Logic," The International Journal of Multiphysics, vol. 6, pp. 7-16, 2012.
- Svarc, P. and Dvorak, V., "Numerical and Experimental Studies of Laminar Natural Convection on a Horizontal Cylinder," Engineering Mechanics, vol. 20 ,pp. 177-186, 2013.
- Grafsrønningen, S., Jensen, A., and Reif, B. A. P., "PIV Investigation of Buoyant Plume from Natural Convection Heat Transfer above a Horizontal Heated Cylinder," International Journal of Heat and Mass Transfer, vol. 54, pp. 4975-4987 ,2011.
- Grafsrønningen, S. and Jensen, A., "Simultaneous PIV/LIF Measurements of a Transitional Buoyant Plume above a Horizontal Cylinder," International Journal of Heat and Mass Transfer, vol. 55, pp. 4195-4206, 2012.
- Persoons, T., O'Gorman ,I. M., Donoghue, D. B., Byrne, G., and Murray, D. B., "Natural Convection Heat Transfer and Fluid Dynamics for a Pair of Vertically Aligned Isothermal Horizontal Cylinders," International Journal of Heat and Mass Transfer, vol. 54, pp. 5163-5172, 2011.
- Marsters, C. F., "Natural Convective Heat Transfer From a Horizontal Cylinder in the Presence of Nearby Walls," The Canadian Journal of Chemical Engineering, vol. 53, pp. 144-149, 1975.
- Al-Alusi, T. R., "An Experimental Study of Natural Convection Heat Transfer From a Horizontal Cylinder Array Vertically Aligned to and Confined by a Single Wall and Two Walls," PHD, Mechanical Engineering, Oregon State University, 1989.
- Saha, A. K., "Unsteady Free Convection in a Vertical Channel with a Built-in Heated Square Cylinder," Numerical Heat Transfer, Part A: Applications, vol. 38, pp. 795-818, 2000.
- Moulai, S., Korichi, A., Fohanno, S., and Polidori, G., "Buoyancy-Assisted Mixed Convection Flow over a Heated Square Cylinder on a Vertical Channel," presented at the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (HEFAT2014), 2014.
- Mathis, P., Burgholz, T. M., Freitag, H., Rohn, M., Schraven, M., and Müller, D., "Heat Transfer Enhancement of Free Convection Flows in Vertical 2D channels With Kármán Vortex Streets : An Experimental Study," presented at the CLIMA 2016 - 12th REHVA World Congress / Per Heiselberg - organizer, Seiten/Artikel-Nr: 9 Seiten, 2016.
- Samish, M. F. and Mahendra, P. N., "Parametric Studies on Heat Transfer by Natural Convection from Inclined Cylinder Placed in Vertical Channel - an Overview," International Research Journal of Engineering and Technology (IRJET), vol. 04, pp. 355-360, 2017.
- Taherian, G., Nili-Ahmadabadi, M ,.Karimi, M. H., and Tavakoli, M. R., "Flow Visualization over a Thick Blunt Trailing-Edge Airfoil with Base Cavity at Low Reynolds Numbers Using PIV Technique," Journal of Visualization, vol. 20, pp. 695-710, 2017.
- Karbasi pour, M., Nili-Ahmadabadi ,M., Taherian, G., and Minaeian, A., "Experimental Study of Natural Convective Flow over a Hot Horizontal Rhombus Cylinder Immersed in Water via PIV Technique," Journal of Applied Fluid Mechanics, vol. 10, pp. 735-747, 2017.