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Study of a proposed design of an ice rink plant

1Project facts

Type: Sport, detailed studies
Consultant: EQUA
Client: PEAB
Summary: A detailed design proposal for an ice rink plant, where the excess heat is used for heating the building.

Challenge

In Sweden, the building regulations allows a building to be heated by excess heat from processes, if it in a satisfactory manner can be shown that it will work. In this case the excess heat is from chillers for ice preparation. To show that the building follows the building regulations, there was need for a detailed simulation model of the building and its plant.

The plant, based around a CO2 chiller with the excess heat recycled in 8 steps using three groups of stratified tanks connected in a loop, had to be modelled in detail.

Solution

The building was modelled using IDA ICE with the Ice Rinks and Pools extension. The ice model was rewritten to take the hourly ice preparation of removing ice and applying water into account. As there was a detailed schematic of the proposed plant available, it was used to create the plant model with associated controls.

The plant model consist of the CO2 chiller and recycling of the condenser heat in 8 steps; (1) final heating of hot water, (2) heat for dehumidifying, (3) heat to room heaters, (4) hot water to ice preparation truck, (5) heating for ventilation, (6) melting of excess ice, (7) pre-heating of hot water, (8) heat of the ground below the ice to avoid freezing. If the temperature after all this recycling is still higher than + 25 ° C, the heat is removed by a heat rejection coil in the relief air stream of the air handling unit.

 


The concept of decoupling was applied; one parent model containing the central HVAC-systems and five child models containing one or two storeys and their zones. Each child model was run on a separate processor to increase simulation speed. To achieve balanced air flow in the VAV-system the exhaust air from the mall concourse was modelled as a pressure-controlled system with leaks between the shops and the concourse.

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Result

The net total energy use simulated was 78 kWh/m2. The average value for ice rinks in Sweden is 264 kWh/m2 (year 2009). The model also made it possible to rise warnings about a few possible problems with the design:

  • There is a risk that the chillers can’t deliver the heat needed during the coldest period. If the air temperature above the pitch gets lower, the chiller will produce less heat which may cause a negative spiral of too little heat produced. This can be prevented by turning on the lights above the pitch during cool nights.
  • In the proposed design of the air handing system, a coil for heat rejection of excess heat from the chiller was used in a way that there were risk of unnecessary ventilation of the building by moist air. The simulations led to a suggestion to change the design.


 


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