Investigation of how Insulation affects the pipe system in the soil for ice rinks

Abstract: In Sweden, ice rinks are one of the largest energy consumers in the public building sector, requiring, each ice rink, about 1050 MWh/year, from which approximately 42 % is used by the refrigeration system. The goals of this project is to study the cooling system in the floor of indoor ice rinks placed at Sweden and achieve a solution against the problem of permafrost in the soil, due to low temperatures, and against the problem of the large amount of energy lost through the ground, due to low efficiency. In order to success in this challenge, five different models performed with COMSOL Multiphysic 3.5 have been simulated and studied to observe the energy saving that can be obtained by changing different design parameters, such as property of the concrete, insulation layer or heating pipes layout. According to the results the following conclusions have been obtained. On one hand, regarding the thermal conductivity, models design with high thermal conductivity concrete, conducts heat in an easier way than the normal concrete, and it will enable higher and quicker amounts of heat transferred through the slab. The improved thermodynamic properties of Concrete layer allow using the refrigerant 5,4 ºC higher temperature to keep the ice at a desired temperature. So, it must be pointed out that in terms of heat transfer, the concrete layer that supports the cooling pipes is one of the most important parts of the structure. On the other hand, as far as the insulation layer is concerned, the best option is to place one below heating pipes, due to the energy losses are reduced from 9 W/m2   to 0,4 W/m2. Finally, regarding to the cooling pipes depth, it must be pointed out that when the pipes are raised up 50 mm, the refrigerant temperature required to maintain the desired ice surface properties has been increased from -16 ºC to -9 ºC. So it can be concluded that increasing thermal conductivity concrete, placing insulation layer below heating pipes and raising up the cooling pipes, it is possible to achieve an energy saving around 33,6 MWh/year, being 7,6 % of the total energy consumption.