Effects of inclined baffle location and Prandtl number on natural convection in a cavity (original) (raw)
Related papers
The purpose of this study is to investigate the effect of inclination angle on flow field and heat transfer in a differentially heated square cavity with two insulated baffles attached to its isothermal walls. The isothermal walls are at different temperatures. The walls that make an angle φ with the horizontal are adiabatic. In our formulation of governing differential equations, mass, momentum and the energy equations are applied to the cavity and the baffles. To solve the governing differential equations a finite volume code based on Pantenkar's simpler method is utilized. The results are presented for various Rayleigh number in form of streamlines, isotherms as well as Nusselt number. It is observed that for all baffle lengths and baffle positions when o 90 = ϕ the Nusselt number is almost minimum. In addition the Nusselt number decreases as baffle length increases, generally. Finally it is shown that Nusselt number changes with baffles position.
Effect of baffle on convective heat transfer from a heat generating element in a ventilated cavity
Heat and Mass Transfer, 2009
This paper reports the results of a numerical and experimental investigation of mixed convection from a heat-generating element in a vented cavity with/without a baffle arrangement. Numerical investigations are carried out to determine the best position of the baffle on the walls of a rectangular chamber. The effect of varying the baffle heights and the position on the enhancement of heat transfer from the heater is investigated. Experiments were carried out for a heater located centrally in a parallelepiped that has an air inlet and an outlet port. The vertical baffle is fixed on the bottom wall of the chamber. After a detailed parametric study, correlations have been developed for the average Nusselt number and the maximum dimensionless temperature occurring in the heat generating element. Comparison of the numerical and experimental results for the geometry considered showed good agreement.
Effect of inclined thick fin on natural convection in a cavity heated from bottom
Progress in Computational Fluid Dynamics, An International Journal, 2015
In this study, natural convection heat transfer in a square cavity with an adiabatic fin mounted on a vertical wall was investigated numerically. Vertical boundaries were adiabatic and horizontal boundaries were isothermal at different constant temperature. Two-dimensional equations of conservation of mass, momentum and energy were solved using finite difference method. Successive under relaxation (SUR) method was used to solve linear algebraic equations. Results were obtained for various geometrical parameters as the thermal conductivity ratio (RK = 0.1, 1.0 and 10), inclination angle of the fin (30° ≤ φ ≤ 150°), thickness of the fin (0.033 ≤ t ≤ 0.2), and Rayleigh numbers (10 3 ≤ Ra ≤ 10 6). Location and length of fin was fixed as h = w = 0.5. Results were presented with streamlines, isotherms, local and mean Nusselt numbers. It was found that Rayleigh number and the fin mounted on the wall had significant effect on natural convection heat transfer and flow field. The thick fin can be used as control parameter of heat and fluid flow.
Assessment of the Baffle Effects on the Mixed Convection in Open Cavity
2018
Several experimental and numerical studies were carried out to determine the effects of a vertical unheated baffle on the mixed convection heat transfer process in a square crosssectional bottom-grooved cavity heated from three sides. The mixed convection heat transfer and fluid flow within the cavity were evaluated by the buoyancy parameter, Reynolds number, Grashof number, and Richardson number. In the numerical part, the validated CFD model has been used to solve the governing continuity equations for the temperature and velocity distribution. The wall temperature profile and the Nusselt numbers were investigated and presented in this study. The experimental results show that the maximum temperature values increased by increasing the baffle height and the maximum Nusselt numbers were found at the full length of the baffle. The comparison between the numerical and experimental study was done and shown a good agreement with a maximum deviation of ±17%. Index Term— Heat transfer, Mi...
Thermal Science, 2014
In the present paper, natural convection fluid flow and heat transfer in a square cavity heated from below and cooled from sides and the ceiling with a thin fin attached to its hot bottom wall is investigated numerically. The right and the left walls of the cavity, as well as its horizontal top wall are maintained at a constant temperature T c , while the bottom wall is kept at a constant temperature T h ,with T h > T c. The governing equations are solved numerically using the finite volume method and the couple between the velocity and pressure fields is done using the SIMPLER algorithm. A parametric study is performed and the effects of the Rayleigh number and the length of the fin on the flow pattern and heat transfer inside the cavity are investigated. Two competing mechanisms that are responsible for the flow and thermal modifications are observed. One is the resistance effect of the fin due to the friction losses which directly depends on the length of the fin, whereas the other is due to the extra heating of the fluid that is offered by the fin. It is shown that for high Rayleigh numbers, placing a hot fin at the middle of the bottom wall has more remarkable effect on the flow field and heat transfer inside the cavity.
Heat and Mass Transfer, 2011
Natural convection heat transfer in an inclined fin attached square enclosure is studied both experimentally and numerically. Bottom wall of enclosure has higher temperature than that of top wall while vertical walls are adiabatic. Inclined fin has also adiabatic boundary conditions. Numerical solutions have been done by writing a computer code in Fortran platform and results are compared with Fluent commercial code and experimental method. Governing parameters are Rayleigh numbers (8.105 ≤ Ra ≤ 4 × 106) and inclination angle (30° ≤ and ≤ 120°). The temperature measurements are done by using thermocouples distributed uniformly at the wall of the enclosure. Remarkably good agreement is obtained between the predicted results and experimental data. A correlation is also developed including all effective parameters on heat transfer and fluid flow. It was observed that heat transfer can be controlled by attaching an inclined fin onto wall.
International Journal of Heat and Mass Transfer, 2008
Buoyancy driven convection in a square cavity induced by two mutually orthogonal and arbitrarily located baffles is studied numerically. The baffles are of different sizes and the flow is two-dimensional. The coupled governing equations were solved by finite difference method using Alternating Direction Implicit technique and Successive Over-Relaxation method. The steady state results are presented in the form of streamline and isotherm plots. It is found that buoyancy force plays a key role and overall heat transfer in the cavity is enhanced for higher values of both baffle-cavity ratios. Flow inhibition emerges as a deciding factor and diminishes heat transfer when the horizontal baffle is located above the center of the cavity.
NUMERICAL STUDY OF HEAT TRANSFER CHARACTERISTICS IN AN ENCLOSURE WITH BAFFLES
A numerical study is conducted to investigate the fluid flow and heat transfer characteristics in a vertical ventilated enclosure with baffle placed at the side wall and all walls are assumed adiabatic. An external cold fluid flow enters into the enclosure through an opening over the left vertical wall and is exited through an outlet in opposite side wall. The two dimensional mathematical models includes the systems of four partial differential equations of continuity, Navier-Stokes equation and energy equation solved by the finite difference method. Uniform grids are used in entire computational domain. The differential equations are discretized using Central Difference Method and Forward difference method. The discritized equations with proper boundary conditions of numerical solutions are sought by obtaining Leibmann’s Successive under Relaxation (SUR) method. It has been done on the basis of stream function and vorticity formulation of the two dimensional Navier-Stokes equation and continuity equation and then the temperature distribution at all nodes is calculated by solving Energy equation. The flow field is investigated by numerical simulations for fluid flowing with a Reynolds number in the range 50Re300 for Prandtl number 0.01Pr 2.0 and Richardson number 0≤Ri≤10. Numerical results are obtained for different values of Reynolds number, Prandtl number & Richardson number. Heat transfer rates at the heated baffle is presented in terms of average Nusselt Number .It is observed that maximum heating efficiency is achieved with this configuration for the higher values of Reynolds number, Richardson number and Prandtl number. As the length of baffle increases the heating efficiency decreases.
International Journal of Engineering Research and Technology (IJERT), 2021
https://www.ijert.org/numerical-analysis-on-natural-convection-in-a-square-enclosure-with-thin-baffles-on-vertical-walls-at-different-positions https://www.ijert.org/research/numerical-analysis-on-natural-convection-in-a-square-enclosure-with-thin-baffles-on-vertical-walls-at-different-positions-IJERTV10IS070076.pdf Natural convection is the mode of heat transfer which occurs due to the existence of temperature gradient. It didn't require any external agent such as fan, pump and blower; it not only saves energy but avoids unwanted noise. Enclosure is a square segment which is a regular geometry, found in a number of applications such as a fully filled duct pipes, electronic systems, computer technologies, air conditioning applications, lubrication system, solar collector, a sheet metal covered store, a solar air heater and a compact plate heat exchanger etc. The current study investigates laminar natural convection in a square enclosure with isothermal vertical walls along with two thin baffles at different positions on them and with adiabatic base and top of the enclosure. The domain is filled with air. This two-dimensional study focuses attention to understand changes in flow and temperature field development due to variation in position of baffles for each cases of Rayleigh number varies. The flow behaviour and thermal characteristics have been investigated in different cases through streamlines and isotherms respectively. Complete domain has been chosen for analysis. Asymmetric solutions are also observed for some of the cases. These results are confirmed by development of the corresponding convection loops and also by the variation of Average Nusselt number. Finally, the thesis report summarizes the effects of different parameters on rate of heat transfer.