Wood chips as thermal insulation of snow

Snow (and ice) cooling is in some areas an alternative cooling technique to chillers. However, to utilise snow cooling during the summer, storage is needed. Snow storages were traditionally insulated by sawdust. A large demonstration plant has been in operation since 2000 for cooling the regional hospital in Sundsvall, Sweden. This storage is thermally insulated by larger wood chips. This paper summarizes laboratory testing of some key factors that influence the functioning of cutter shavings (another kind of wood chips) as thermal insulation. The melt rate significantly increased with increased wind velocity, light intensity (from spotlight bulbs), air temperature, and air humidity. A 1 cm thicker layer of cutter shavings decreased the melt rate about 0.097 kg m− 2 h− 1, within the studied layer limits of 2.5 to 7.5 cm. The melt rate with initially wet cutter shavings was about the same as for initially dry cutter shavings. This was explained by the increased evaporation which balanced increased thermal conductivity. Evaporation was found to be an important part of the energy balance and reduced the melt rate. Solar light reflectivity of new cutter shavings was measured in a separate outdoor experiment, found to be about 20%.