Rheological Behavior of Air in the Two-Pass Solar Collector

Abstract

This study pivoted on the flow behavior of air streams across solar air collectors provided with wooden baffles under the absorber plates. The two-pass system was used for both flat and finned surfaces. The von Kármán momentum integral and Blasius equations were solved with the help of PDPE and ODE45 techniques. The solution was assumed to be a part of the initial value problem (IVP). The energy analysis of both solar air collectors was carried out using the Hottel–Whillier–Bliss equation (HWB) equation. The Sankey diagram was used for energy distribution across the solar collectors. The gray box modeling approach was adopted to comprehend the airflow behavior across the channel. The objective of this study is to examine the intrinsic behavior of the proposed design. The displacement of boundary to compensate for the momentum of air stream (θt) decreased by 31.25%–62.50% with an increase in mass flow rate (m)˙of 24.69%–49.38% for the flat plate collector (FPC). Similarly, the shear stress posed by the absorber plate (τw) dropped by 15.89%–37.20% with the augmentation of the mass flow rate. The momentum thickness for the flat plate with triangular fin (FPTF) increased relatively by 31.25%, compared to FPC at 8.10 g·s−1. The estimated value of collector efficiency (ηI) FPTF soared up by 4%–11.51% when it was juxtaposed against the corresponding values derived for FPC. The wall shear stress near the absorber plate followed that of a second-order Gaussian model. It was noticed in this study that the addition of the fin slowed down the shear effect and the momentum defect of airstream at the same mass flow rate.

Developing a thermodynamic model for the circulating air using an opaque system

“…The signal processing was performed using the data acquisition system (ADAMS4018). The device specification along with the manufacturer details is provided in Table 2 24 . The collector was placed at 45° from the horizontal surface.…”

“…The geometrical drawing of the collector is provided in Figure 1. The construction materials used to make the collector are tabulated in Table 1 24 . The signal processing was performed using the data acquisition system (ADAMS4018).…”

“…The construction materials used to make the collector are tabulated in Table 1. 24 The signal processing was performed using the data acquisition system (ADAMS4018). The device specification along with the F I G U R E 1 Geometrical drawing of the solar air collector.…”

“…manufacturer details is provided in Table 2. 24 The collector was placed at 45°from the horizontal surface. On the first pass of the collector, the right bottom corner was perforated for the air passage to the second pass.…”