Heat Transfer In Triangular Duct Research Articles

Assessment of heat transfer in a triangular duct with different configurations of ribs using computational fluid dynamics

Abstract Numerical investigation was performed to improve heat transfer in triangular ducts using ribs of different sizes and shapes. Increased heat transfer may be achieved by the roughness in the duct surface, which is a prospective and successful method. It is shown that the sectional shape of the roughness given on the area exposed to heat has a major impact on the effective performance of heat transfer channels. This research will study the results of using different shapes and sizes of roughness components, such as triangular rib (e/W = 0.1, 0.2, and 0.3) as well as semi-circular rib (R/W = 0.1, 0.2, and 0.3). Likewise, the influence of rib width b (b/w = 0.2, 0.4, and 0.6) is examined using computational fluid dynamics for variable Reynolds number (1,000 < Re < 1,800) at fix rib height (e/W, R/W = 0.1). ANSYS FLUENT 2020 R1 is used to model the heat and the flow dynamics in roughened ducts. The best performance was for the semi-circular ribs. At a Reynolds number of 1,200, the optimum ratio of enhancement (ε) for the semi-circular rib sample e = 0.2 × W was 1.717. Additionally, sample 4 has the greatest Nusselt number across all Reynolds numbers and is the best-shaped sample. Furthermore, the pressure drop and the friction factor also increase when the rib width is increased, the sample (p = 0.2 × W) highest pressure drop and coefficient of friction values.

Effect of Apex Angle, Porosity, and Permeability on Flow and Heat Transfer in Triangular Porous Ducts

This paper presents an analysis of forced convection flow and heat transfer in triangular ducts containing a porous medium. The porous medium is isotropic and the flow is laminar, fully developed with constant properties. Numerical results for velocity and temperature distribution (in dimensionless format) in the channel are presented for a wide range of porosity, permeability, and apex angles. The effects of apex angle and porous media properties (porosity and permeability) are demonstrated on the velocity and temperature distribution, as well as the friction factor (fRe) and Nusselt numbers in the channel for both Isoflux (NuH) and Isothermal (NuT) boundary conditions. The consistency of our findings has been verified with earlier results in the literature on empty triangular ducts, when the porosity in our models is made to approach one.

Analysis of Laminar Mixed Convective Heat Transfer in Horizontal Triangular Ducts

Numerical simulations for fluid flow and heat transfer in triangular ducts are carried out. Flow is considered to be laminar, hydrodynamically, and thermally developing. Heat transfer by both forced and natural convection is taken into account. Simulations are carried out for constant wall temperature cases which are at a higher temperature than the inlet temperature of the fluid. The effect of Rayleigh number on bulk mean temperature and Nusselt number is studied. Isotherm and secondary velocity profile formed because of natural convection is shown at different locations with varying Rayleigh number. The effect of the apex angle of the triangular duct on Nusselt number and bulk mean temperature is studied. Results are compared with the cases of mixed convective heat transfer in a square duct.

Augmented heat transfer in triangular ducts with full and partial ribbed walls

Fully developed heat transfer coefficients and friction factors in triangular ducts with full and partial ribbed walls were experimentally obtained for Reynolds numbers between 10-10. The vertex corners of the triangular ducts were 90, 55, and 35 deg. Five rib configurations were tested: full and partial 90-deg transverse ribs, full and partial 45-deg crossed ribs on three-wall, and partial 45-deg crossed ribs on two-wall of the triangular duct. The results show that heat transfer coefficients were higher on the ribbed walls and the 90-deg vertex corner of the triangular duct than on the 55-deg vertex corner, and subsequently higher than those on the 35-deg vertex corner. The heat transfer coefficients and friction factors in triangular ducts with partial ribbed walls (90or 45-deg ribs) were 10% higher than those with full ribbed walls. The results also show that heat transfer coefficients and friction factors were higher in triangular ducts with 90-deg transverse ribs (full or partial) than those with 45-deg crossed ribs. The semi-empirical friction and heat transfer correlations in ribbed triangular ducts were obtained.

HEAT TRANSFER IN TRIANGULAR CHANNELS WITH ANGLED ROUGHNESS RIBS ON TWO WALLS

Abstract Leading edges of internally cooled gas turbine engine airfoils are often cooled convectively by flow through triangular cross-sectioned passages containing roughness ribs on two of their three sides. The roughness augments heat transfer coefficients and thereby increases the ability of the cooling air to cool the airfoil leading edge. Ribs are normally placed on the two sides of the passage that constitute forward sections of the airfoil pressure and suction surfaces, and the third side, a cooling passage divider or internal bulkhead, is usually left smooth. The present study is an experimental investigation of developing local convection heat transfer in triangular ducts with square ribs at various rib angles, orientations, and pitch-to-diameter ratios on two of the three channel walls in conjunction with a smooth third wall. Stream-wise development of spanwise-averaged Nusselt numbers is presented for both rough and smooth walls, along with typical spanwise variations. Results were obtained for...