4 ms·
the article doesn't mention how heat is stored, it just says "the system extracts heat from the air and stores it above ground for reuse". do you know how they
by kobalsky 2y ago
the article doesn't mention how heat is stored, it just says "the system extracts heat from the air and stores it above ground for reuse".
do you know how they do it?
- pfdietz 2y agoI don't know in detail, but they could do something like this: compress the air, making it hot, then run the hot air through a packed bed of small objects (pebbles, bits of iron). As the air goes through the bed the heat is transferred to the material. This ends with a temperature gradient across the bed (hot at one end, cooler at the other). To discharge, the flow of air is reversed: in at the cool end, out at the hot end. This sort of design (a counterflow heat exchanger, basically) keeps the delta-T at each point low, so the system has low entropy production. A similar heat exchanger could be designed with a liquid thermal storage medium, where the air and the liquid are flowed past each other in opposite directions (separated by solid walls, most likely). The hot storage tank would be insulated. An advantage of this design is the pressure of the liquid storage tanks needn't be high, unlike the vessel containing the pebbles in the earlier described system. All these may need to dump some waste heat to the environment as a consequence of inefficiencies in the system.