Thermal and fluid dynamic characteristics of flow through triangular cross-sectional duct: A review

Duct geometry is one of the important factors which influence the heat transfer in laminar and turbulent flow conditions. Along with heat transfer, pumping power required for fluid flow through a duct is also an important concern in industries. In most of the industrial applications, the flow is turbulent in nature. Many studies were carried out to understand laminar and turbulent heat transfer through non-circular (such as triangular, rectangular, trapezoidal, hexagonal, elliptic and sinusoidal etc.) cross-sectional ducts. This paper presents the review of various studies which were carried out on triangular duct. Only natural and forced convective heat transfer using Newtonian fluids studies, based on experimental and numerical are considered in this article. For the improvement of heat transfer in triangular duct, different shaped artificial roughness were also used by mainly researchers and the results were presented by generating correlations for both heat transfer and friction factor. It can be concluded that the optimum heat transfer takes place under axially uniform wall heat flux with peripheral uniform wall temperature boundary conditions as compared to all other boundary conditions. The heat transfer can also be enhanced by rounding of corners but it also increases the pumping power which is directly linked with the operating cost.