Stability of D-mannitol upon Melting/Freezing Cycles under Controlled Inert Atmosphere

Some Heat Transfer Data for a Mannitol Derived Phase Change Material

“…Several authors have detected some problems on the mannitol usage as thermal energy storage material. Rodríguez-García et al [13] indicate that there is a severe degradation of this material when working on thermal energy storage processes when it is subjected to long stages above its fusion temperature. The clear phase change disappears and a vitreous transition phenomenon takes place and from a visual inspection of the degraded material it can be concluded that its solid structure is lost.…”

Development of a new methodology for validating thermal storage media: Application to phase change materials

“…34,35,42,56 This decrease in ΔH ph-ch was lower or even disappeared when the same PCMs formed composites with inert materials. 45,48,51,76,77 In contrast, other organic PCMs with T ph-ch above 100°C such as sugar alcohols, 61,64 hydroquinone, 61 salicylic acid, 61 benzamide, 62 or liquid crystals 66 showed strong degradation after only a few melting/freezing cycles. For the case of solid-solid PCMs, only a slight decrease (less than 4%) in ΔH ph-ch was observed after the cycles.…”

“…Those PCMs include pure substances, eutectic mixtures, and composites that undergo either solid‐liquid or solid‐solid phase transitions. In contrast, only few stability studies have been found for PCMs intended to temperature applications above 100°C.…”

“…In order to perform cycling tests, some authors used differential scanning calorimetry (DSC), whereas the majority used set‐ups adapted and/or designed on purpose. Those set‐ups included thermostatic chambers, thermal water baths, electric hot plates with temperature control, weathering chambers, ovens with controlled heating, and, in few cases, also with a cooling control . The advantage of using a DSC apparatus for thermal cycling is that phase change temperature ( T ph‐ch ) and calculated enthalpy (Δ H ph‐ch ) are recorded directly for each cycle, so that their evolution can be monitored without interrupting the test or removing the sample.…”

“…If a DSC apparatus is not used to perform the cycling tests, these thermophysical properties have to be measured after a certain number of cycles mainly by DSC or thermogravimetric analysis (TGA). Additionally, for detecting chemical or structural changes in the PCMs after the cycling, some authors applied analytical techniques like, for example, Fourier transform infrared spectroscopy (FTIR), 46,48,51,57,59,61,63,65,69,75,78,83,88 visible and ultraviolet spectroscopy (VisUV), 64 X-ray diffraction (XRD), 60,74 high performance liquid chromatography (HPLC), 61 or scanning electron microscopy (SEM). 57,60,74,75,77,80 Almost all references shown in Table 1 report on tests based on consecutive heating/cooling cycles.…”