Numerical Simulation of Natural Convection in Rectangular Enclosures of Varying Aspect Ratios and its Feasibility in Environmental Impact Management Studies

<p>Author's abstract: Numerical simulation was used to investigate natural convection in horizontal and vertical enclosures with and without an internal heat source. Natural convection in rectangular enclosures is found in many real-world applications. Included in these applications are the energy efficient design of buildings, operation and safety of nuclear reactors, solar collector design, passive energy storage, heat transfer across multi-pane windows, thermo-electric refrigeration and heating devices, and the design-for-mitigation of optical distortion in large-scale laser systems. Considering all these applications, especially controlling heat transfer in nuclear power plants, knowledge and research results of natural convection in enclosure play a vital role in environmental impact management studies. This study simulated horizontal enclosures heated from below (configuration 1) and vertical enclosures heated from the side (configuration 2) with a variety of different aspect ratios (AR) and Rayleigh numbers (Ra). Each aspect ratio (1, 2, 4, 6, 8, and 10) was examined using different sets of Rayleigh numbers. The first numerical experiment used only external Rayleigh number (RaE = 2x104, 2x105, and 2x106) which simulated natural convection in enclosures for outside temperature gradient only. The second case used a constant external Rayleigh number (RaE = 2x105) with a changing internal Rayleigh number (Ral = 2x104,2x105, and 2x106). The third simulation used a constant internal Rayleigh number (Ra l = 2x105) and a changing external Raleigh number (RaE = 2x104, 2x105, and 2x106). All three cases were simulated for each configuration and at each aspect ratio. The streamline and isotherm flow patterns were created to reflect each case. The average heat flux ratio and convection strength were also calculated. Tests with the external temperature gradient only confirmed previous studies. There were many notable outcomes in this study which are discussed in the main body of this thesis work. When RaE > Ral, the results were similar to the study with a varying external Rayleigh number (RaE) and no internal heat source.</p>

Name thesis:degree_name

Master of Science in Applied Engineering (M.S.A.E.)

Level thesis:degree_level

Thesis (open access)

Discipline thesis:degree_discipline

Department of Mechanical Engineering

Year dc:date.available

2012

Author dc:creator

• Walker, Charles R.

Contributors dc:contributor

• David Williams
• Gustavo Molina

• ETD
• Natural convection
• Rectangular enclosure
• Numerical simulation
• Average heat flux ratio
• Convection strength
• Rayleigh number
• Energy Systems
• Engineering
• Heat Transfer, Combustion
• Structural Materials

Repository record dc:identifier

https://digitalcommons.georgiasouthern.edu/etd/1018

OAI identifier oai:identifier

oai:digitalcommons.georgiasouthern.edu:etd-2051