A hospital in central Sweden discovered an uncommon solution to meet its summer season cooling wants by storing snow from winter and utilizing it months later. The Sundsvall Regional Hospital makes use of a big snow storage system designed to protect winter chilly till the hotter months.The Sundsvall hospital has a flooring space of 190,000 sq. metres. In accordance with Science Direct, the hospital’s annual cooling demand is about 1,000 MWh, with a most cooling energy requirement of 1,500 kW. The native authorities have been searching for a cooling resolution that fitted environmental targets and nationwide laws.The findings of the undertaking have been printed in a 2001 analysis paper by Kjell Skogsberg and Bo Nordell in Chilly Areas Science and Know-how.
A big snow storage space
The snow storage facility was in-built 1999. It coated an space measuring 140 metres by 60 metres and had a complete capability of 60,000 cubic metres, equal to about 40,000 tonnes of snow.Originally of the undertaking, solely about half of the overall storage capability was anticipated for use. The storage space was constructed as a shallow pit with a watertight asphalt base.The system was designed to decelerate the pure melting of the snow. A layer of wooden chips was positioned over the saved snow to behave as thermal insulation. In accordance with the report, this diminished pure melting to about 20% to 30% of the overall snow quantity.The researchers additionally studied how a lot insulation was wanted to maintain the snow out there by way of the summer season. Their simulations targeted on a 30,000-cubic-metre snow storage facility.
How snow can retailer cooling
Snow and ice soften at 0°C, and melting requires a big quantity of warmth. Warmth from the environment is absorbed because the snow melts. Which means that the saved snow can act as a supply of cooling when its meltwater is circulated by way of a cooling system.The researchers seemed on the quantity of warmth wanted to heat ice, soften it after which heat the ensuing water. This concerned the warmth capability of ice, the warmth of fusion of water and the warmth capability of water.The hospital system used meltwater slightly than straight circulating the snow. Water from the snow storage was pumped to the hospital. After the water helped cool the hospital, the hotter water was despatched again to the snow storage space. This created a cycle during which the saved snow equipped the cooling whereas regularly melting.
A storage space of 140×60 m with a capability for 60,000 m3 (40,000 tons) of snow was constructed in 1999.
Significance of insulation
With out insulation, the saved snow wouldn’t have lasted by way of the summer season. The researchers calculated that an uninsulated 30,000-cubic-metre snow pile would have disappeared by June 17. That might have been properly earlier than the top of the hospital’s cooling season.They then in contrast the outcomes when sawdust was used as insulation. With a 0.10-metre layer of sawdust, about 12,169 cubic metres of snow remained within the simulation. With a 0.20-metre layer, about 19,040 cubic metres remained. The thicker layer carried out higher as a result of it diminished warmth switch from the encompassing atmosphere into the snow.With 0.20 metres of sawdust, the utmost pure meltwater fee was calculated at 77.4 cubic metres per day. This occurred in direction of the top of June.The examine concluded that with thermal insulation, the saved snow may cowl the hospital’s cooling demand from Could to August.
How cooling was completed earlier
The researchers additionally famous that folks had used ice for cooling lengthy earlier than fashionable refrigeration. In historical Greece, ice was collected from lakes and rivers and saved in buildings insulated with supplies resembling sawdust. Related strategies have been utilized in Europe and North America till cooling machines grew to become widespread within the early twentieth century.Japan had additionally developed a number of types of snow and ice cooling. Conventional Himuros and Yukimuros used stone or picket buildings to retailer ice or snow alongside meals resembling greens and fruit. One other Japanese methodology, referred to as the All Air System, cools air by way of direct contact with snow.
Different snow storage concepts
The researchers additionally checked out seasonal snow storage research elsewhere. In Ottawa, Canada, researchers examined whether or not snow faraway from streets and public areas could possibly be transported to a big snow deposit and saved for later cooling.One proposed deposit had a quantity of 90,000 cubic metres and was coated with a reflective and insulating layer. The examine discovered that circulating meltwater was the best solution to extract chilly.One other chance was storing snow in underground rock caverns. Such techniques could possibly be in-built city areas and will scale back the space over which snow would must be transported.The examine additionally famous an issue with snow collected from cities. City snow can comprise excessive ranges of pollution, that means the meltwater might must be managed and handled.
