# Numerical Analysis on the Performance of a Radiant Cooling Panel with Serpentine-Based Design
## 3 Results and Discussions
### Analysis and Discussions  
The simulation results presented in Section 3.2 show that the cooling capacity of the RCP can be enhanced by manipulating the flow configurations of the RCP. It was found that the proposed flow configurations enhanced the cooling capacity of RCP by 172.57% for Design 2 and 125.03% for Design 3. The percentage increase is compared with the cooling capacity of Design 1, which is the conventional serpentine flow configuration that acts as a benchmark for the two proposed designs. The RCP operates in an enclosed environment, in which the air and all the surfaces are kept at a constant temperature. Chilled water enters the RCP at 15 \({}^{\circ}\)C, resulting in a temperature difference between the RCP and the conditioned surrounding. Heat exchanges occur between the RCP and the conditioned surroundings due to the temperature difference. From this natural phenomenon, the heat exchange that occurs is more efficient in Design 2 compared to Design 1 and Design 3, because Design 2 enables a more uniform temperature distribution with the highest cooling capacity.  
As shown in Equation (15), the cooling capacity, which is also known as total heat flux, as absorbed by the RCP, is the summation of radiation and convection heat transfer between the surrounding temperature and the panel's surface. Our results agree with ASHRAE's definition of radiant systems, where the radiation heat transfer amounts to 60% of the total heat flux absorbed by the RCP. Thus, these results could be applied to develop new RCP flow configurations with maximum cooling potential, because the cooling capacity of RCP is often insufficient in hot and humid climates, due to condensation problems. If proper RCP flow configurations have been discovered, the required cooling capacity can be achieved at a relatively higher chilled water temperature.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Design**} & \multicolumn{1}{c}{**Total Loss Coefficient**} & \multirow{2}{*}{**Friction**} & \multirow{2}{*}{**Theoretical Pressure**} & \multirow{2}{*}{**Simulated Pressure**} & \multirow{2}{*}{**Percentage**} \\  & & \(\sum\)**k** & & **Factor, f** & & **Drop (Pascal)** \\ \hline
1 & Pipe 1 & 1.2 & 0.1429 & 127.8954 & 129.4225 & 1.19 \\ \hline \multirow{2}{*}{2} & Pipe 1 & 0.6 & 0.1429 & 74.3315 & 74.8937 & 0.76 \\  & Pipe 2 & 0.6 & 0.1429 & 74.3315 & 75.1780 & 1.14 \\ \hline \multirow{3}{*}{3} & Pipe 1 & 0.4 & 0.1429 & 56.4650 & 56.3966 & 0.12 \\  & Pipe 2 & 0 & 0.1429 & 20.7530 & 19.8199 & 4.50 \\ \cline{1-1}  & Pipe 3 & 0.4 & 0.1429 & 56.4650 & 56.7390 & 0.49 \\ \hline \hline \end{tabular}
\end{table}
Table 10: Simulated and theoretical pressure-drop values.  
Figure 14: Effect of the number of bends on a pipe’s pressure drop.  
Although the proposed flow configurations effectively enhanced the cooling capacity of the RCP, the simulated results are recommended for validation with an experimental investigation. As this research is only for a single panel, appropriate experimentation and testing conditions are necessary to find out the required number of panels that should be integrated and distributed over the ceiling for effective cooling. With a larger number of panels, a higher water flow rate is needed throughout the large radiant surface of the RCP. Therefore, proper experimental research is needed to evaluate the pumping power of these designs to determine their applicability.