Experimental and numerical study on buoyancy-induced convection between two facing isothermal surfaces in an enclosure partitioned with a new arrangement of dividers; an application to double-glaze windows

Abstract

Energy demand management is one of the most important factors that affects the economy of a society. Energy demand is directly related to energy consumption, and the lower energy consumption, follows the lower energy demand. Buildings are one of the most important sources by about 40 % energy consumption in any country and windows by about 10 % energy loss, as one of the components of buildings, play a key role in this regard. In most investigions, closed enclosures have been simulated as double-glaze windows and owing to this, the suppression of thermal exchange amount by incorporating geometric rectifications into closed enclosures has gained attentions more and more. In this experimental and numerical study, a vertical closed enclosure partitioned with multiple horizontal straight dividers, is considered and a new arrangement is introduced for the dividers inside the enclosure. To this end, each pair of dividers is placed off-center of the enclosure and in the opposite direction to other adjacent pair. Similar to double-glaze windows, the proposed enclosure has two isothermal cold and warm walls whereas, other walls are kept adiabatic. Then, optimized values of decision parameters including the Rayleigh number (Ra) varying from 6.5 × 10³ to 1.4 × 10⁴ and incline angle of the dividers (φ) from 0° to 180°, which results in a minimum thermal exchange amount, are specified. According to experimental results, the suggested asymmetric arrangement for the dividers, leads to a maximum of 17.01 % suppression in the thermal exchange amount between the isothermal surfaces, in comparison with symmetric arrangement of the dividers.