Experimental study of developing turbulent flow and heat transfer in ribbed convergent/divergent rectangular ducts

Abstract

The article represents an experimental investigation of friction and heat transfer characteristics of divergent / convergent rectangular ducts with an inclination angle of 1? in the y-axis. Measurements were taken for a convergent / divergent rectangular duct of aspect ratio AR at inlet1.25 and outlet in convergent channel 1.35; but in case of divergent duct it can be reversed. The four uniform rib heights, e = 3, 6, 9 and 12 mm the ratio between rib height to hydraulic mean diameter (e/Dm) are 34.8, 69.7, 104.6 and 138.7 a constant rib pitch distance, P = 60 mm has been used. The flow rate in terms of average Reynolds number based on the hydraulic mean diameter (Dm) is 86 mm of the channel was in a range of 20,000 to 50,000. The two ceramic heating strip of 10 mm thickness is used as a heating element have attached on top and bottom surfaces for the test sections. The heat transfer performance of the divergent / convergent ducts for 3, 6, 9 and 12 mm ribs was conducted under identical mass flow rate based on the Reynolds number. In our experiments has totally 8 different ducts were used. In addition, the acceleration / deceleration caused by the cross section area, the divergent duct generally shows enhanced heat transfer behavior for four different rib sizes, while the convergent duct has an appreciable reduction in heat transfer performance. From result point view divergent duct with 3 mm height ribbed square duct gets maximum heat transfer coefficient with minimum friction loss over the other convergent / divergent ducts.

Numerical investigation and experimental validation of convective heat transfer in air square duct

“…Bhadouriya et al (2015) conducted experimental and numerical study of fluid flow and heat transfer in a twisted square duct. Karthikeyan et al (2015) presented experimental study of developing turbulent flow and heat transfer in ribbed convergent and divergent rectangular ducts. Zhang et al (2021) studied flow characteristics and structural parametric optimization design of rectangular plenum chambers for HVAC systems.…”

Numerical simulation of flow reversal at high Rayleigh number in a vertical square duct - an application of the spectral method

“…The MHD flow and heat transfer in the presence of a confined square cylinder was investigated by Farahi and Hossein [20], using the SM82 equations. Karthikeyan et al [21] presented the experimental study of developing turbulent flow and heat transfer in ribbed convergent /divergent rectangular ducts. Fully developed laminar flow and heat transfer in a 2-D horizontal channel with staggered fins was numerically analyzed by Turgut and Arslan [22].…”

Numerical investigation of 3D turbulent forced convective heat transfer and friction characteristics of a square duct

“…Heat transfer characteristics of a wavy walled duct have been analyzed numerically by Ramgadia et al [2]. Karthikeyan et al [3] carried out an experimental investigation on developing turbulent flow and heat transfer in a convergent-divergent rectangular ribbed duct with an inclination angle of 1 0 to the y-axis using four different rib heights similar to the work of Wang et al [4] and it has been reported that that the divergent duct gives better result in heat transfer enhancement for all rib heights. Promvonge et al [5] found that the rise of blockage ratio leads to enhancement in heat transfer and friction losses in a square duct with inline 60 0 V-shaped ribs mounted on two opposite walls.…”