## 2 Comparison of Experimental Devices  
### Summary of Technical Specifications  
This article is based on a survey comparing the experimental conditions and procedures of 18 testing devices from 10 different institutions. The device names used are formed according to the abbreviations of the respective institute designations. The technical specifications and the experimental conditions of these devices are summarized in Table 1. Devices are divided into thermal cycling stability tests (type A), tests on PCM utilizing stable supercooling (type B), and tests on the stability of PCS and encapsulated PCM (type C). The experimental devices for thermal cycling stability tests (type A) are typically used to test common PCM such as salt hydrates, paraffins, and other organic materials (e.g., fatty acids and esters). Further information about the investigated materials and their measured stability as well as further specifications of the devices can be found in the quoted references. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline
**Device Name** & **Sample Size** & \(\Delta T/C\) &
\begin{tabular}{c} **Heating Cooling** \\ **Rate/k min-1** \\ \end{tabular} & **Cycles Per Day** & **Atmospher** & **Stability Tests** & **Sample Container** & **Ref.** \\ \hline CIEMAT I (A) & 60–100 mL & RT\({}^{1}\)–350 & 1–20 & 1 & air & \(T(I_{\rm cycles},\) Dec, mf(I)\) & glass, ceramic & [18,19] \\ CIEMAT II (A) & 10 mL & RT-500 & 1–20, natural & 1 & air & \(T(I_{\rm cycles},\) Dec, mf(I)\) & ceramic & [18,19] \\ CIEMAT II (A) & 60 mL & RT–500 & 1–20, natural & 1 & air, N\({}_{2}\), Ar & \(T(I_{\rm cycles},\) Dec, mf(I)\) & ceramic & [20] \\ EHU (A) & 5 g & \(-\)45–200 & variable & variable & air, N\({}_{2}\), Ar & DSC, vis., XRD, FTIR & glass, metal & - \\ HSLU (A) & \(1\times 100\)ml, \(3\times 25\) & \(-\)40–180 & 10; 0.5 & 10 & air & \(T(I_{\rm cycles},\) Dec, vis., & glass & - \\  & mL, \(5\times 8\) mL & & & & & & & & \\ ES capsules (A) & \(-\)221 \({}^{\circ}\) & \(-\)10–80 & 1; 1 & 10 & air & DSC, rf(I), RM & polystyrene & [21] \\ ES RePiter (A) & 10–100 mL & \(-\)30–200 & variable & \(<\)24 & air & DSC, vis & stainless steel & \\ LAME (A) & 3–6 mL & \(-\)5–125 & 13.7 & \(<\)140 & air & DSC & glass, plastic & [22, 23, 24, 25] \\  & LGCgcE (A) & 270 mL & 5–80 & 0.05–0.3 & 2–3 & air, vacuum & \(T(I_{\rm cycles},\) Dec & PMMA & [26] \\  & LITT (A) & 10–100 ml & \(-\)20–180 & variable & variable & air & \(T(I_{\rm cycles},\) Dec & glass, metal, plastic & [27] \\  & ULD-GEREA I (A) & 180 \(<\) 0.5 mL & 4-99 & 50; 50 & 100 & air & DSC, rf-FIR, TGA & polypropylene & [42, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38] \\ ULD-CREIA II (A) & 154 L & 20–400 & 1; natural & 1 & air & DSC, rf-IR, TGA & stainless steel & [29, 30, 31, 32, 33, 34, 35, 36, 37, 38] \\ ULD-CREIA III (A) & 8 L & \(-\)10–80 & 0.5; 1 & 2 & air & DSC, rf-IR, TGA & aluminum, stainless steel & [39] \\  & ZAE (A) & 60 mL & \(-\)30–220 & 1 & 2 & air & \(T(I_{\rm cycles},\) Dec, vis. & glass, stainless steel & [7] \\ DTU full-scale (B) & 100–200 L & 20–90 & 1; 0.5 & 0.2 (0.4\({}^{\circ}\)) & air & \(T(I_{\rm cycles},\) \(\Delta I_{\rm cycles}\) & metal, plastic & [40, 41, 42] \\ DTU best loss (B) & 200 g & 20–90 & 1; natural & 0.25 (0.5\({}^{\circ}\)) & air & \(T(I_{\rm cycles},\) \(\Delta I_{\rm cycles}\) & glass & air, metal lid & [43] \\  & DTU multiple (B) & 10 \(\times\) 30 L & 8–93 & 0.15; 3–4 & 0.25 & air & \(T(I_{\rm cycles},\) \(\Delta I_{\rm cycles}\) & stainless steel & [44] \\  & ISE PCS (C) & 3.5 L & \(-\)10–80 & 140; 100 \({}^{\circ}\) & 1300 \({}^{\circ}\) & -5 & DSC, \(\Delta I_{\rm cycles},\) \(\Delta I_{\rm cycles}\) & stainless steel & [45] \\ \hline \end{tabular}  
\({}^{1}\) RT = room temperature, \({}^{2}\) without supercooling of SAT, \({}^{3}\) max. bath volume, \({}^{4}\) at 200 kDa\({}^{-1}\), \({}^{5}\) PCS in contact with water.  
\end{table} 
Table 1: Specifications of testing devices (device types A-C explained in Section 2.1).