SUPERCOOLING STABILITY OF SODIUM ACETATE TRIHYDRATE COMPOSITES IN MULTIPLE HEAT STORAGE UNITS

摘要

Keeping sodium acetate trihydrate (SAT) in supercooled state can be utilized to store heat loss free over longperiods. The main risk with this technology is that the SAT may crystalize spontaneously and release the storedheat before desired.A test rig with 10 marketed heat storage units with water and 35 kg sodium acetate trihydrate composite wasbuilt and multiple heating and cooling cycles were carried out with the units. It was monitored if the sodiumacetate trihydrate remained supercooled in the 3 days storage period or if the solidification startedspontaneously. The units were charged with an inlet temperature of 87°C, and then discharged with inlettemperatures of 14°C, 22°C, 28°C　or 35°C. Spontaneous solidifications occurred more frequently duringdischarge in the test cycles with lower discharge temperatures compared to higher inlet temperatures.