# Numerical Design and Laboratory Testing of Encapsulated PCM Panels for PCM-Air Heat Exchangers
## 2 Methods
### Design Procedure
#### 2.1.1. 3D Simulations  
Nine 3D designs were generated (Figure 4, shapes 1-7 and 9-10) and compared with a hemispherical (shape 0), a teardrop (shape 8) and the existing panel. Each design was drawn with different rounded lozenges, protrusion and groove radius based on literature suggestions. All geometries vary by height and pitch, ridge pitch length, ridge pitch width, ridge radius (Table 1). For the CFD simulations the surface temperature was fixed at 20 \({}^{\circ}\)C because it is a common melting point for PCMs used for this application. The inlet channel temperature was set as 26 \({}^{\circ}\)C because this is a common value for the return air through recirculation or the outside air during cooling periods. The Reynolds number of 18,736 (which is equivalent of 130 L/s) for all cases was used as it represents the average  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{**2D Simulation of Shape 9**} \\ \hline \multirow{2}{*}{**Shape 9 Variations**} & **Ridge Height/Panel** & **Ridge Pitch/Panel** & **Ridge Radius (r)** \\  & **Length (s/l)** & **Length (s/l)** & **(mm)** \\ \hline Shape 11 & 0.219 & 0.044 & 2.5 \\ \hline Shape 12 & 0.063 & 0.022 & 7.5 \\ \hline Shape 13 & 0.063 & 0.022 & 7.5 \\ \hline Shape 14 & 0.188 & 0.044 & 2.5 \\ \hline Shape 15 & 0.250 & 0.044 & 2.5 \\ \hline Shape 17 & 0.188 & 0.033 & 2.5 \\ \hline Shape 18 & 0.188 & 0.022 & 2.5 \\ \hline Shape 19 & 0.219 & 0.044 & 2.5 \\ \hline Shape 20 & 0.219 & 0.056 & 2.5 \\ \hline Shape 21 & 0.281 & 0.044 & 3.0 \\ \hline Shape 22 & 0.219 & 0.044 & 2.5 \\ \hline Shape 23 & 0.281 & 0.044 & 2.5 \\ \hline \multicolumn{3}{c}{**2D Simulation Refinement**} \\ \hline \multirow{2}{*}{**Shape 9 in Module**} & **Gap between panels/Panels Duct** & **Panel Thickness/Duct** & **Number of Panels (p)** \\  & **Height (h/h)** & **Height (h/h)** & **Number of (p)** \\ \hline Shape 24 & 0.042 & 0.069 & 9 \\ \hline Shape 25 & 0.042 & 0.079 & 8 \\ \hline Shape 26 & 0.042 & 0.124 & 6 \\ \hline Shape 27 & 0.048 & 0.101 & 6 \\ \hline Shape 28 & 0.053 & 0.101 & 6 \\ \hline Shape 29 & 0.063 & 0.121 & 5 \\ \hline Shape 30 & 0.051 & 0.151 & 4 \\ \hline Shape 31 & 0.034 & 0.080 & 8 \\ \hline Shape 32 & 0.030 & 0.070 & 9 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Modelled geometrical variations of the panel for 2D cases.  
Figure 3: PCM panel control volume (r: radius; e: ridge height; s: spacing between ridges; h: distance between panels (air gap)).  
airflow during the charging period. The distance between panels were the same as the existing configuration. The range of variation was based on the following: (i) Ridge height per airgap [\(0.125<e/h<0.313\)]: With the air gap between panels fixed, the height was augmented until the pressure drop considerably increased; (ii) Ridge pitch length [\(0.033<s/l<0.078\)]: The number of ridges added per length (lines of ridges) were limited by the cost of production and ease of manufacturing; (iii) Ridge pitch width [\(0.033<w_{r}/w<0.867\)]: The ridges added per width were limited by the cost of production and ease of manufacturing; and (iv) Ridge radius [\(1.5<r<6\)]: The range of radius was limited by the cost of production, pressure drop and ease of manufacturing.