## 3 Results and Discussion  
### Contact Heat  
In Figure 7, the temperatures displaying the tested linings' dependence on the exposure time of the outer shell to the contact heat are presented. This chart shows a clear difference in the heating process of assemblies based on phase-change materials (\(A\) and \(C\)) and assemblies based on reference materials (\(B\) and \(D\)). The first difference between the above-mentioned kinds of samples is already visible in the initial stage of the heating process (in the first 4 min). In this stage, the temperature of all tested assemblies increases linearly over time. Assemblies containing PCMs heat up more slowly than their counterparts containing PP macrogranules. The temperature rise rate \(R_{\mathrm{T}}\)[0, 1, 2, 3, 4] during this stage is 1.46 \({}^{\circ}\)C\(\cdot\)min\({}^{-1}\) (assembly \(A\)) and 1.56 \({}^{\circ}\)C\(\cdot\)min\({}^{-1}\) (assembly \(C\)), while for assemblies \(B\) and \(D\) are 2.39 \({}^{\circ}\)C\(\cdot\)min\({}^{-1}\) and, 3.23 \({}^{\circ}\)C\(\cdot\)min\({}^{-1}\), respectively. It should be assumed that the observed lower \(R_{\mathrm{T}}\)[0, 1, 2, 3, 4] values for PCM-containing assemblies are due to the fact that already after about 1 min of exposure time, some amount of the n-octadecanet content in PCM macrocapsules warms up to melting temperature (28 \({}^{\circ}\)C). As a consequence, a slow isothermal melting process of n-octadecane begins. It should be noted that the lower parts of the PCM macrocapsules (closest to the hot plate) are heated to melting temperature (28 \({}^{\circ}\)C) earlier than the lining is. As can be seen in Figure 7, the lining of the PCM-containing  
Figure 7: Lining temperature versus exposure time of the outer shell to contact heat. assemblies reaches 28 \({}^{\circ}\)C in the third minute of exposure time. After the fourth minute of exposure time, a clear difference in the temperature increase between PCM-containing assemblies and PP-containing assemblies was observed. In contrast to assemblies \(A\) and \(C\), for which a second slower heating stage can be distinguished, assemblies \(B\) and \(D\) heat up at a rate comparable to that of the first stage. This means that, in PCM-containing assemblies, when the entire amount of n-octadecane reaches the melting temperature, intensive melting of the octadecane occurs as a result, which absorbs a significant part of the heat flux generated by the hot plate. In this stage of the heating process, the temperature rise rate of the lining is milder than in the previous heating stage, \(R\)T\({}^{4-17}\) = 0.25 \({}^{\circ}\)C\(\cdot\)min\({}^{-1}\) for assembly \(A\) and \(R\)T\({}^{4-12}\) = 0.29 \({}^{\circ}\)C\(\cdot\)min\({}^{-1}\) for assembly \(C\). For assembly \(A\), this stage lasts from 4 min to 17 min, while for assembly \(C\) from 4 min to 12 min. The five-minute difference is due to the different construction of the nonwoven fabric in these assemblies. Assembly \(A\), in which there is a thicker and more porous nonwoven fabric (1) than in assembly \(C\) (nonwoven fabric 2), due to its greater thermal insulation, created a more effective barrier to the heat flux passing from the thermal barrier to the lining. The third stage of the heating process (starting for assembly \(A\) at the seventeenth minute while for assembly \(C\) at the twelfth minute), is characterized by a higher temperature rise rate of the lining compared to the second stage. At this stage, the entire amount of n-octadecane has melted, and the heat generated by the hot plate is not absorbed for the n-octadecane phase transition but is entirely converted into a temperature increase in the assemblies. To compare the effectiveness of thermal insulation of the assemblies containing PCMs inserts (\(A\) and \(C\)) with the reference assemblies containing PP inserts (\(B\) and \(D\)), the time gains \(\Delta t_{\text{AB}}\) and \(\Delta t_{\text{CD}}\)--the time difference in which the respective assemblies reached the temperature of 36 \({}^{\circ}\)C--were calculated (indicated in Figure 7).