Heat and Mass Transfer
M. Rahimi; M. Khalafi-Salout
Abstract
Heat transfer from the internal surfaces of a vertical pipe to the adjacent air gives rise to the air flow establishment within the pipe. With the aim of optimizing the convective air flow rate in a vertical pipe, the details of the flow and thermal fields were investigated in the present study. Conservation ...
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Heat transfer from the internal surfaces of a vertical pipe to the adjacent air gives rise to the air flow establishment within the pipe. With the aim of optimizing the convective air flow rate in a vertical pipe, the details of the flow and thermal fields were investigated in the present study. Conservation equations of mass, momentum, and energy were solved numerically using simple implicit forward-marching finite difference scheme for a two-dimensional axis-symmetric flow. In order to evaluate and optimize the air flow rate passing through the pipe, the position and intensity of the wall heat flux were altered when the total employed heat transfer rate was constant. Based on the results of the numerical analysis, relatively more air flow rate was achieved when more intensified heat flux was employed at the lowest part of the vertical pipe. This finding was then validated using a simple experimental setup. The results of the present study could be useful in the design and application of buoyancy-assisted natural ventilation systems.
Heat and Mass Transfer
M. Rahimi; M. Mortazaei
Abstract
Jet impingement heat transfer is an effective and practical approach that is employed in many industrial processes where heating, cooling, or drying is required. Details of the heat or mass transfer rate have been investigated both experimentally and numerically and can be found in the published literature. ...
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Jet impingement heat transfer is an effective and practical approach that is employed in many industrial processes where heating, cooling, or drying is required. Details of the heat or mass transfer rate have been investigated both experimentally and numerically and can be found in the published literature. In most of the numerical studies, control-volume approach has been employed to solve the governing equations of the thermal and flow fields. Using this numerical approach, a pressure correction equation is usually developed from the conservation equations in a rigorous manner to obtain the pressure distribution. Avoiding the complexities encountered in the traditional manner, a full implicit finite-difference method was developed for the first time and applied for studying jet impingement heat transfer. Similar to the velocity components, static pressure was also treated as an unknown variable in this approach. Specifications of both flow and thermal fields were obtained for two cases of confined and unconfined jets by the proposed numerical method. It was demonstrated that this novel numerical approach was a straightforward method, which required no additional equation for pressure calculation, and had the potential use in other two- or three-dimensional flow and thermal field analysis.
