To perform the comparison between the numerical Nusselt numbers and the reported ones, we consider a cavity with differentially heated walls; two opposite vertical walls heated at different temperatures and the others were adiabatic. The Rayleigh number of 2.3×106 was considered, which is the same as in the experiment.

Table 5 presents the comparison between the present work and the theoretical and experimental convective, radiative and total Nussetl numbers of Ramesh et al. in 1999 (experimental) and Balaji and Venkateshan en 1994 (numerical). From these results, we can see that for Rayleigh of 2.3×106 the differences between the convective Nusselt number of Ramesh and the present work was 13.2%, meanwhile for the Balaji was 11.45%. For the radiative Nusselt number, the highest difference was for Balaji, but for the experimental one, the difference decreases until 14.61%. That is due to the fact that Balaji considers 2-D model and we considered 3-D model. Nevertheless, the differences between the total Nusselt number and the present work was 1.6% for Ramesh and 5.58% for Balaji.

3. Conclusions

This paper presented the influence of the radiative heat transfer of a three dimensional cavity with a semitransparent wall with solar control coating, considering that the temperature distribution of the test glass is function of the thermal interaction between the interior and the exterior of the cavity. The results indicated that the model can represent very closely the experimental air measurements in the interior of the cavity, thus the model can be considered verified experimentally. From the absorbed thermal energy in the solar control coating, 12.4% was for radiative energy and 11.0% was for convective energy, meaning that the radiative exchange between surfaces plays and important role in the heat transfer process for this cavity.

Additional results were the comparison with reported work. The results indicated that the theoretical model can reproduce the theoretical and experimental total Nusselt number with an approximation less than 6%. However, there is a difference, high 16.9% and

lowest 10.14% when individual convective and radiative Nusselt numbers were

considered.