A Numerical Study of Turbulent Natural Convection in a Square Enclosure Using a Two Equation Model | Chapter 01 | Advances in Mathematics and Computer Science Vol. 3

In this study the performance of one numerical turbulence model, k- ε is accessed. In predicting heat transfer due to natural convection inside an air-filled square cavity. Turbulent natural convection in an enclosure plays an important role in the field of heat transfer and buildings environment. Natural turbulent convection is square air cavities having isothermal vertical and highly heat – conducting horizontal walls are compared with the experimental data obtained for these cavities at a varying Rayleigh numbers, 1.8 x 109, 1.44 x 1010 and 1.15 x 1011. In carrying out numerical investigations, a two – dimensional, low turbulence, two – parameter k- ε model known as the Low – Reynolds – number k- ε turbulence model was used. The vorticity – vector potential formulation was used to eliminate the need to solve the pressure terms. The vorticity, vector potential energy and two – equation model with their boundary conditions were solved using finite difference approximations. The results of the investigation are presented for the distribution of the velocity and temperature components. The non – linear terms   and   in the averaged momentum and energy equations respectively are modelled using the k- ε model to close the governing equations. The cavity is maintained at 313K on the hot wall and 293K on the opposite cold wall. The horizontal walls are adiabatic. The results obtained show that as the Rayleigh number increases, the values of the stream function increases. As the Rayleigh number increases, uniform distribution of heat inside the cavity is achieved.

Author(s) Details

Mutili Peter Mutisya
School of Pure and Applied Sciences, Kenyatta University, Box 43844 – 00100, Nairobi, Kenya.

Awuor Kennedy Otieno
School of Pure and Applied Sciences, Kenyatta University, Box 43844 – 00100, Nairobi, Kenya.

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View Volume: https://doi.org/10.9734/bpi/amacs/v3

Pressure Drop and Heat Transfer Analysis for Satisfactory Operating Conditions of Rotary Heat Exchangers | Chapter 07 | Current Research in Science and Technology Vol. 2

A computational analysis in a rotary heat exchanger subject to pre-established mass flow rate is performed. The heat transfer rate, the pressure drop and the outlet temperatures of gas streams are calculated from different matrix porosity values. The fluid flow and the convective heat transfer coefficient are determined from correlations. The total heat transfer is obtained using the Effectiveness-NTU method specific to rotary heat exchangers. Three typical rotary exchangers with both streams under the laminar flow regime are investigated. A range of porosity values that provide good thermal exchange and low pressure drop in the equipment is chosen for each examined equipment. The behavior of the outlet temperatures of each gas stream as function of porosity is also analyzed. The results show that the porosity ranges shorten when the typical pressured drop values for each rotary exchanger are introduced in the analysis. In addition, the behavior of the outlet temperatures is compatible with the behavior of the heat transfer rate as the porosity changes.

Author(s) Details

P. C. Mioralli
Federal Institute of São Paulo – IFSP, Campus Catanduva, Brazil.

E. Avallone
Federal Institute of São Paulo – IFSP, Campus Catanduva, Brazil.

P. H. Palota
Federal Institute of São Paulo – IFSP, Campus Catanduva, Brazil.

P. S. G. Natividade
Federal Institute of São Paulo – IFSP, Campus Catanduva, Brazil.

C. E. Luizete
Federal Institute of São Paulo – IFSP, Campus Catanduva, Brazil.

Read full article: http://bp.bookpi.org/index.php/bpi/catalog/view/78/1058/878-1
View Volume: https://doi.org/10.9734/bpi/crst/v2