Enhanced gas-liquid absorption through natural convection studied by neutron imaging

Short-Lived Interfaces in Energy Materials

“…Recently, functional storage systems became available. These reach performance values near to the anticipated and required temperature swing, power-and energy density (Fumey et al, 2022). The reason for this is not of technical nature, but due to the detrimental relation between power-and energy density.…”

“…In addition to mass transport on a microscopic scale, mass transport occurs on a macroscopic scale via convection (Fujita, 1993;Li et al, 2016). Neutron imaging gave indication that this convection can be induced by buoyancy (Fumey et al, 2022, see Figure 1B). With appropriate design, the convection flux provides continuously fresh NaOH solution to the gas-liquid interface.…”

“…The underlying physical principle is based on the approach "improving the dynamic interface". This approach has been shown to be equally successful in heat storage in aqueous sodium hydroxide solution (Fumey et al, 2020;Fumey et al, 2022), and is discussed in detail in subsection 2.2. Hydrogen as an energy carrier requires safe and efficient storage strategy, which is still an obstacle for its widespread introduction (Andersson and Grönkvist, 2019).…”

“…With appropriate design, the convection flux provides continuously fresh NaOH solution to the gas-liquid interface. Based on these observations, Fumey et al (2022) constructed a mass and heat exchanger with an area specific power of 1.28 kWm −2 with an extrapolated thermal energy storage density of 243 kWh m −3 , near to the theoretical limit of 360 kWhm −3 . This solution may be generalized by the approach "separation of interface and mass transport": at the interface, reaction is fast; to guarantee fast uptake into the bulk, the material at the interface is transported by convection (Figure 1B).…”

“…Nuclear methods are in general very well suited for depth profiling, such as neutron imaging. The spatial resolution of neutron imaging is only in the micrometer range (Morgano et al, 2018), but its great advantages are the time resolution (Zboray and Trtik, 2018) and the compatibility to the harsh conditions as is relevant in catalysis (Terreni et al, 2018), heat storage (Fumey et al, 2022), and fuel cells (Boillat et al, 2017;Minnaar et al, 2020).…”