Ph.D. Tezi Görüntüleme | |||||||||||||||||||||
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| Summary: Unsteady natural convection in a prismatic cavity was studied. Natural convection in a table top refrigerator, which represents a prismatic cavity, was experimentally and numerically investigated for open door and closed door cases. The effects of barriers, placed at the entrance of the refrigerator and at different levels from the bottom, were also numerically investigated. A commercial software (Fluent-5) was used for numerical analysis of two dimensional laminar natural convection. It is assumed that the prismatic cavity has a vertical opening, a cooled wall at top and insulated side walls. For open door case, the mean Nusselt number for the cooling surface increases and reaches steady state as the time increases. The mean Nusselt numbers obtained by experimentally and numerically are quite close. The barrier, placed to the lowest level at the entrance, causes a decrease in heat transfer although the other barriers, placed to higher levels, shows no important effect on heat transfer. The time to reach steady state increases by a decrease in heat transfer in the case of the barrier placed to the lowest level.It is observed that the temperature and velocity distributions for open door and closed door cases are significantly different. The time to reach steady state increases for closed door case. The mean Nusselt number for the cooling surface decreases and gets very small as the time increases, in contrast to open door case. Keywords: Natural Convection, Laminar Flow, Open Cavity, Rectangular Cavity, Rectangular Enclosure, Refrigerator
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