The comparison between the models is done based on a slat projected width of 25.2 mm, slat spacing of 20 mm and
slat reflectance of 0.8.
The slat curvature radius is chosen to be 25 mm to give the ratio of the slat curvature radius to projected slat width of 1. The slat thickness is chosen to be 2 mm to give the ratio of the slat thickness to projected slat width of 0.1.
The slat curvature and the slat thickness are chosen similar to the slat that Chantrasrisalai and Fisher (2004) have used in their work.
Fig. 18 shows a comparison between the optical properties of a curved slat blind calculated from the developed model and a flat slat blind calculated by using the EnergyPlus model with thickness correction at slat angle of 45 degree.
The effect of slat curvature can be seen from the difference in the optical properties calculated from two different models. The effect of slat curvature is clearly seen on the values of the direct-to-direct transmittance and direct-to-diffuse transmittance at profile angle of 45 degree.
The effect of slat curvature is also seen on the direct-to-diffuse transmittance and reflectance when the profile angle is beyond 60 degree.
Fig. 19 shows the comparison between the optical properties calculated from EnergyPlus model with and without thickness correction.
The difference in the optical properties from the two models indicates the effect of slat thickness only.
The effect of slat edge correction due to its thickness is also clearly seen in the optical properties at higher profile angle. Fig. 20 shows the comparison between the optical properties of the curved slat blind calculated from the developed model and a curved slat blind without thickness calculated from the Pfrommer model.
The difference in the optical properties is clearly seen on the direct-to-direct transmittance and reflectance.
The difference is contributed to the effect of slat thickness.
The effect of using only two reflections between the slats in Pfrommer model and the effect of thickness are also shown on the difference in the direct-to-diffuse transmittance, reflectance and absorptance shown in Fig. 20.
Fig. 21 shows the comparison between the optical properties of a curved slat blind without thickness and a flat slat blind without thickness calculated from Pfrommer model.
The difference in the optical properties shown in Fig. 21 is contributed to the effect of slat curvature.
Fig. 22 show the comparison between the optical properties calculated from the EnergyPlus model and the Parmelee model.
The agreement in the results predicted from both models is good.
Fig. 23 shows the comparison between the optical properties of a curved slat blind calculated from the developed model and from the Parmelee model with thickness correction.
The effect of slat curvature is clearly seen on the direct-to-direct transmittance and direct-to-diffuse transmittance at profile angle of 45 degree.
The difference in the optical properties is also seen on the direct-to-diffuse transmittance and reflectance when the profile angle is greater 65 degree.