## 2 Materials and Methods
### Thermal Testing of Phase Change Panels  
Figure 5 is a schematic diagram of the thermal testing apparatus of the phase change panel. As shown in the figure, the phase change panel was placed vertically, with five K-type thermocouple measurement points arranged at the center on both sides. The uncertainty of the thermocouples was 0.5 \({}^{\circ}\)C. The heating temperature was set using an intelligent digital temperature control box with an uncertainty of 1 \({}^{\circ}\)C, which heated the cast aluminum heating plate with the thermal resistance. The dimensions of the heating plate were 400 mm \(\times\) 400 mm \(\times\) 20 mm, matching those of the phase change panel. Once the temperature of the cast aluminum heating plate was stable, it was placed on one side of the phase change panel, ensuring that the contact surfaces were fully aligned. The intelligent digital temperature control box and cast aluminum heating plate were manufactured by Dayu Electric Company of Xinghua City, China. In the heating process, the surface of the phase change panel in contact with the heating plate was designated as the heating surface and the opposite surface as the non-heating surface. The temperatures at the measurement points were recorded every minute using a multi-channel temperature tester. The average temperature of the measurement points on each side of the phase change panel was taken as the corresponding surface temperature. The indoor air temperature was recorded in real time using a Stevenson screen. To prevent varying environmental temperatures from affecting the test results, the non-heating surface and all peripheral surfaces of the phase change panel were covered with insulation cotton at the same area to reduce convective heat transfer between the phase change panel and  
Figure 4: The actual application scenarios of the phase change panel. Figure 5: A schematic diagram for the thermal testing apparatus of the phase change panel. the air. The multi-channel temperature tester and thermocouple wires were manufactured by Yongpeng Instrument Company of Shenzhen City, China, and the Stevenson screen was manufactured by Renke Electronic Technology Company of Jinan City, China. Figure 6 shows the layout of the thermocouple measurement points, which are symmetrically distributed around the center of the phase change panel. The distance between adjacent measurement points was 80 mm, with the positions of the measurement points on both surfaces of the phase change panel being identical. In the structure of the phase change panel, the thermal conductivity of the material surrounding the aluminum box was significantly higher than that of the PCM, exhibiting the characteristics of a thermal bridge [26]. Due to the higher temperatures in these areas, the thermocouple measurement points were positioned as close to the center of the phase change panel as possible to more accurately analyze the heat transfer mechanism of the panel. The determination of the heating temperature and duration is directly related to the analysis results of the heat transfer mechanism of the phase change panel. The heating temperatures and durations for different experimental groups are shown in Table 2.  
Experimental group 1 tested the effect of aluminum rods on enhanced heat transfer. The side of the phase change panel with the welded aluminum rods was used as the heating side, allowing heat to be directly transferred through the aluminum rods. This setup was used to find the impact of the aluminum rods on the melting process of the internal PCM. The heating temperature was set to 45 \({}^{\circ}\)C and the heating duration was 6 h.  
Experimental group 2 served as the control group for experimental group 1. An aluminum alloy phase change panel without aluminum rods was used. The heating temperature was set to 45 \({}^{\circ}\)C and the heating duration was 6 h. Since this phase change panel did not have welded aluminum rods, it is unnecessary to specify the heating side of the panel.