New Highly Thermally Conductive Thermal Storage Media

Miscibility gap alloys with a ceramic matrix for thermal energy storage

“…This is a typical MGA microstructure with a high volume fraction of discrete PCM (Al) particles, well separated by the matrix phase (MgO) as seen in previous work [12,13,16]. No evidence for microstructural degradation was found.…”

“…From these, the features of those chosen for development are that they involve common and safe materials, have high energy density with a phase change at a useful temperature, possess high thermal conductivity and do not have very high material costs. In comparison with the graphite-based C-Al MGA [13,17], the cost of the MgO and the Al 2 O 3 MGA is likely to be similar as the ceramic powders are relatively cheap ($500-$800 per tonne). By comparison, AlN is more expensive and it is likely that the cost of AlN-Al MGA would be 2 to 4 times higher than the other two ceramic systems investigated here.…”

“…Figure 9 illustrates the theoretical stored energy density as a function of temperature from an assumed lower storage temperature of 610 °C to an assumed upper temperature of 710 °C. These limits were chosen to match those used to describe the energy density of MGA materials elsewhere [13,16,17,25] and do not indicate any restrictions on the temperature at which the materials can be used.…”

“…Miscibility gap alloys (MGA) form a class of high thermal conductivity solids enhanced by an internal PCM dispersed as fine particles and fully encapsulated within [12,13]. Although the PCM melts and stores latent heat, the materials remain macroscopically solid and immobile.…”

“…); however, recently a number of graphite matrix MGA have been manufactured and tested in relatively arduous conditions [15]. These systems include C-Zn [15], C-Al and C-(Al-Si) [16,17], C-Mg and C-Cu [13].…”