Evaluation of heat pump concepts in ice rinks

Abstract: In Sweden there are about 350 ice rinks in operation today which consume approximately 300 GWh per year. The average energy consumption for a Swedish ice rink is approximately 1000 MWh per year. Ice rink dose not only consume energy it also rejects heat. The rejected heat comes from the refrigeration system that cools down the ice floor. The refrigeration system rejects heat around 700 to 1000 MWh per season. The reason for this study is because of the rejected heat which leads to the question how the rejected heat can be used.The object is to find a heat pump concept that can use the rejected heat or another heat source in an ice rink. Three different heat pump concepts were evaluated. The first heat pump concept use the ice floor as a heat source (called BHP), the second concept use the rejected heat as a heat source (called CHP) and the third concept use the rejected heat to charge an energy storage (called GHP).To accomplish the objective a heat analysis of two ice rinks were made to be able to simulate the heat pump concepts. With the simulation results a life cycle cost was made for a better evaluation. The results from the heat analysis were used for simulating the heat pump concepts. The two ice rinks that were analyzed were Järfälla ice rink and Älta ice rink. The main heat source the two ice rinks uses today is district heating and electricity. Järfälla only use district heating (DH) as a heat source and Älta ice rink use recovery heat, electricity and district heating.The heat analysis of the two the ice rinks showed that the highest district heating consumer was the domestic hot water at 47% of the DH followed by the dehumidifier at 32% of the DH and last the space heating at 22% of the DH. This shows how the heat is used in a general ice rink in Sweden. The temperature levels for the dehumidifier is around 65 °C (only DH part), the domestic hot water at 55 °C and last the space heating at 20 °C. However the heat demand for the ice rinks resulted in 443 MWh for Järfälla and 192 MWh for Älta. To know the size of the heat pump used for the heat pump concepts a heat profile for the ice rinks were made. The result of heat profiles lead to a heat pump size of 105 kW in Järfälla and 45 kW in Älta. The rejected heat for one season in Järfälla is 1000 MWh and 780 MWh in Älta.With the results from the heat analysis the evaluation the heat pump concepts was possible. The COP1 for the CHP resulted at 3,8 and the COP1 for the GHP was assumed to be the same as for the CHP. The COP1 calculations for the BHP concept resulted at 2,5. COP was calculated with collected data from the respective ice rinks refrigeration system. The simulations results were that the BHP and the CHP concept could fulfill the heat demand up to around 79% and the GHP up to around 84% in both ice rinks. The rest of the heat demand is heated with supplementary heat. The life cycle cost (LCC) showed that the CHP concept had the lowest cost followed by the GHP concept. The BHP concept had the highest LCC, because of the low COP. The LCC model dos not include the running cost, the maintenance cost and the energy tariffs for the district heating.The recommended solution is the GHP concept. This is because it is a good investment for the future since other buildings can be connected to the energy storage. The GHP concept is also the solution that fulfills the heat demand best and has the lowest annual energy cost.