Correlations for Natural Convection Between Heated Vertical Plates

Abstract

This paper presents the numerical results of natural convective flows between two vertical, parallel plates within a large enclosure. A parametric study has been conducted for various Prandtl numbers and channel aspect ratios. The results are in good agreement with the reported results in the literature for air for large aspect ratios. However, for small aspect ratios, the present numerical results do not agree with the correlations given in the literature. The discrepancy is due to the fact that the published results were obtained for channels where the diffusion of thermal energy in the vertical direction is negligible. The results obtained in this paper indicate that vertical conduction should be considered for channel aspect ratios less than 10 for Pr = 0.7. Correlations are presented to predict the maximum temperature and the average Nusselt number on the plate as explicit functions of the channel Rayleigh number and the channel aspect ratio for air. The plate temperature is a weak function of Prandtl number for Prandtl numbers greater than 0.7, if the channel Rayleigh number is chosen as the correlating parameter. For Prandtl numbers less than 0.1, the plate temperature is a function of the channel Rayleigh number and the Prandtl number. A correlation for maximum temperature on the plate is presented to include the Prandtl number effect for large aspect ratio channels.

Experimental research on heat transfer of natural convection in vertical rectangular channels with large aspect ratio

“…4 gives out the variation of the average Nusselt number related to the Rayleigh number. In this figure the characteristic length in the Nusselt number and the Rayleigh number was the channel clearance, which was chosen according to the work in literatures [15][16][17][18]. The dots represent the experimental data.…”

“…Since Nusselt numbers were generally correlated with Ra * in these researches, the data of our experiments were also re-correlated with Ra * and compared with the results predicted with correlations in [15][16][17][18] (see Table 2). Fig.…”

Numerical analysis of the most appropriate heat transfer correlations for free ventilated double skin photovoltaic façades

“…These deviations were considered by Olsson C. [12] who argued that the coefficients and exponents of the correlation were determined based on experimental data obtained by Campo et al [32,33]. These experiments provided a limited number of data to fit the correlations, therefore a general extension of this correlation may lead to significant deviations (see Fig.…”

Impact of External Surroundings on Natural Convection in a Vertical Channel Asymmetrically Heated

“…The channel can have adiabatic extensions, be closed in cavities or open domain [7,1,2,17,16]. These different strategies lead to an increase in size of the computational domain which proves to be expensive, both in memory and in computational time [19]. Moreover, interactions between the channel and surroundings are not correctly estimated by these strategies [3,12,13,14].…”