Free Convection in Antisymmetrically Heated Vertical Channels

Abstract

Free convection in a vertical channel with antisymmetrical heating is a special case that has not received a great deal of attention in the literature. Antisymmetrical heating is where the hot wall is heated above the ambient temperature by the same amount that the cold wall is cooled below the ambient, giving equal but opposing buoyancy forces inside the channel. An experimental model was constructed to study antisymmetrical heating inside an isothermally heated vertical channel. Flow visualization was used to obtain the flow field and laser interferometry was used to obtain the temperature field. Based on the measured temperature field, the local and average Nusselt numbers were determined, which were compared with numerical predictions obtained using ansys fluent. A range of Rayleigh numbers were studied for air with a Prandtl number of 0.71. The results show that an open-ended channel with antisymmetrical heating has some similarities to a tall enclosure. The average convective heat transfer can be approximated using an existing correlation for a tall enclosure from the literature.

Modelling of an energy-efficient open double-glazing unit for the main climatic conditions of Mexico

“…With respect to the temperature and the vertical velocity component (see Figure 5), the research found maximum differences of about 1% and 4.5%, respectively. We can conclude that even though the numerical model was considered in laminar steady-state flow and thermal radiation has been neglected, all cases have a good agreement regarding experimental data 37 and the analytical solution for mixed convection in a vertical channel. 38…”

“…The numerical code was validated with the experimental solution for natural convection in an antisymetrically heated vertical channel reported by Roeleveld et al. 37 Table 3 shows the comparison of the average Nusselt number at the hot wall between the present numerical solution and experimental results for three different Rayleigh numbers ( Ra = 1.48 × 10 + 3, Ra = 4.79 × 10 + 3, and Ra = 1.18 × 10 + 3). As can be observed, the results showed maximum deviations between 6.1 and 7.5% for all Ra numbers under analysis.…”

“…Grid sensitivity analysis for the annual warmest design-day in Merida on 25 January 2016 at 11:50 h. Results comparison for the average Nusselt number at the hot wall in an antisymmetrically heated vertical channel reported by Roeleveld et al37 …”