Development of supercoolers for ice slurry generators using icephobic coatings.
Daniel Carbonell, Maike Schubert, Jens Røberg Frandsen, J. Brand, Kevin Erb, Loris Laib, Matteo Munari
Abstract
A supercooler is a heat exchanger that allows to supercool water avoiding ice nucleation on the heat exchanger surface. In this paper, six supercoolers with icephobic coatings were tested for supercooling ice slurry generators. As reference, a supercooler without any coating was used. For coating comparison, three different chemical families were tested at different mass flow rates. Experiments of coated heat exchangers show average supercooling degrees in the range of 3K to 4K. All icephobic coatings improved the supercooling degree respect to the reference non coated case by 7% to 44% at 1000kgh−1 mass flow rate with supercooling powers up to 5 kW. For a mass flow rate of 2000kgh−1 a supercooling power of about 6kW has been reached for five coatings at a temperature of −2.5∘C and hold constant for a time span of 3h. Some coatings could reach lower temperatures at this mass flow, but the experimental setup was limited to this supercooling power. The two coatings performing best in the heat exchanger tests were both from the family class hybrid organic-inorganic silane sol-gel with improvements in the degree of supercooling respect to the reference uncoated heat exchanger of 30% to 40%. The supercooling degrees achieved in the present work are up to two times larger compared to results published in scientific journals until this date using industrially relevant heat exchangers.