Research Papers

Natural Ventilation in a Model Room

[+] Author and Article Information
Sudhakar Subudhi

Department of Mechanical Engineering,  National Institute of Technology Calicut, Kozhikode 673601, Indiasubudhi@nitc.ac.in

K. R. Sreenivas

Engineering Mechanics Unit, JNCASR, Bangalore 560064, Indiajaywant@mecheng.iisc.ernet.in

Jaywant H. Arakeri

Department of Mechanical Engineering,  Indian Institute of Science, Bangalore 560012, Indiajaywant@mecheng.iisc.ernet.in

J. Thermal Sci. Eng. Appl 4(1), 011003 (Feb 24, 2012) (9 pages) doi:10.1115/1.4005606 History: Received August 21, 2011; Revised November 11, 2011; Published February 21, 2012; Online February 24, 2012

Natural ventilation of a model room with water as the fluid medium is studied. It is insulated by air gaps on the four sides and at the top. A constant heat flux has been maintained on the bottom surface of the room. This room is surrounded by a large exterior tank containing water. There are three openings each on two opposing sides of the model room. For any experiment, only one opening on each side is kept open. Fluid enters or leaves these openings and the flow is driven entirely by buoyancy forces. Shadowgraph technique is used for visualization. The buoyancy causes flow to enter through the bottom opening and leaves through the top opening. At the openings, buoyant jets are observed and which have higher or lower relative density compared with that of its environment. The buoyant jet at the inlet interacts with the plumes on the heated bottom plate. From these visualizations, it appears that free convection at bottom plate will be affected by the buoyant jets at the openings and the degree to which it is affected depends on the position and size of openings and distance between inlet and outlet. The flow rate due to the natural ventilation depends on the bottom surface heat flux and the height difference between the openings. The temperatures of the floor, the interior and the exterior are calculated using a simple mathematical model. The values of temperatures obtained in the experiments are reasonably well predicted by the mathematical model.

Copyright © 2012 by American Society of Mechanical Engineers
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Figure 1

Transient natural ventilation with side and top heat losses

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Figure 2

Calculated interior temperature with time for rooms of sizes, 5m × 5m × 5m and 7m × 7m × 7m

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Figure 5

Positions of thermocouples and openings

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Figure 6

Schematic diagram for the interaction between plumes and jet

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Figure 7

Line plumes at the bottom heated surface [12], view looking from top

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Figure 8

Plumes over bottom heated surface [12]

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Figure 9

Buoyant jet at outlet using shadowgraph

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Figure 10

Interaction between plumes and jet

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Figure 11

Temperature-time plot for the case of without openings. There is a band for interior temperature curve as all interior temperatures at different heights are plotted.

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Figure 12

Temperature difference-time plot for the case of without openings

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Figure 13

Temperature-time plot for different positions inside water layer for configuration “BITO”

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Figure 14

Comparison of temperatures of the interior and the bottom plate with that of theory for the case of BITO’

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Figure 15

Temperature differences with time for case of BITO



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