Optimal inclination for maximum convection heat transfer in differentially-heated enclosures filled with water near 4 degrees C
Natural convection in water-filled square cavities inclined with respect to gravity, having one wall
cooled at 0°C and the opposite wall heated at a temperature ranging between 4°C and 30°C, is studied
numerically for cavity widths spanning from 0.02 m to 0.1 m in the hypothesis of temperaturedependent
physical properties, with the main aim to determine the optimal tilting angle for maximum
heat transfer. A computational code based on the SIMPLE-C algorithm is used to solve the system of
the mass, momentum and energy transfer governing equations. Once the vertical configuration, in
which the cavity is differentially heated at sides, is identified by the zero tilting angle, and positive
angles denote configurations with the heated wall facing upwards, it is found that the optimal tilting
angle is positive if the heating temperature is equal or higher than 8°C, whereas it is negative whenever
the heating temperature is lower than 8°C. Moreover, the optimal tilting angle is found to increase as
the cavity width is decreased and the temperature of the heated wall is either decreased or increased,
according as it is higher or lower than 8°C. Sets of dimensionless correlating equations are developed
for the prediction of both the optimal tilting angle and the heat transfer rate across the enclosure.