CFD Simulation and Analysis of Thermal Diffuser for High Temperature Flue Gases

Aja, Ogboo Chikere and Al-Kayiem, Hussain H. and Abdul Karim, Z. A. (2011) CFD Simulation and Analysis of Thermal Diffuser for High Temperature Flue Gases. In: International Renewable Energy and Environment Conference (IREEC 2011), 24 26 June 2011, Kuala Lumpur, Malaysia .

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Experience with vane-less diffuser has shown a large setback in the diffusion process of high temperature working fluids. Without distribution vanes, a thermal jet like flow is created, while the aim of the diffuser is to produce uniform distribution at the exit of the diffuser. The need of guide vanes in a diffuser is an idea born through an experimental problem faced when passing a turbulent high temperature flue-gas through a large angle diffuser. It was expected to have approximate uniform discharge at the exit of the diffuser but was found to create a jet diffused at the rate of 1:2, of inlet to exit, thus the high temperature flue gas concentrated at the centre of the exit thereby affecting the insulation and the experimental result. To solve this problem, a CFD simulation was employed to analyze the process and redesign the system for improved performance. GAMBIT software was used to model the diffuser in two-dimension and FLUENT software was used to simulate the 2-D fluid flow and thermal field, using different arrangement of guide vanes as distributors. The CFD simulation without, and then with guide vane to create uniform flow at the exit of a short diffuser with diverging angle of 57.72o from centre line (diffuser angle, α = 115.44o), inlet to exit aspect ratio of 1:20 and inlet to exit surface area ratio of 1:25 is analyzed in this work. Different guide vanes shapes where employed such as sharp/straight shapes, oval shapes and airfoil shapes. It was found that the airfoil shaped guide vanes offered the best result with most uniform distribution at the exit of the diffuser.

Item Type: Conference or Workshop Item (Paper)
Subjects: T Technology > TJ Mechanical engineering and machinery
Departments / MOR / COE: Departments > Mechanical Engineering
Depositing User: AP Dr Zainal Ambri Abdul Karim
Date Deposited: 05 Dec 2011 03:01
Last Modified: 19 Jan 2017 08:22

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