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Dessiccant Dehumidification

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  rev. 2008-11-25        

Existing Conditions

Dehumidification of ice skating arenas is critical for several reasons, especially in the warmer months when ventilation and infiltration air contains a lot of moisture:

Structural:  When incoming air is cooled, the entrained moisture condenses on structural surfaces.  This causes rotting of wooden components, peeling paint, rusting of structural steel, and spalling of brickwork.  In some arenas a layer of moisture on walkways creates a slipping hazard.

Ice Surface:  Humidity buildup often creates dripping from the ceiling onto the ice surface, which impacts the quality of the ice.  Also, when the indoor air is humid, moisture will continually condense on the ice sheet.

Useability After a Flood:  The ice resurfacer conditions the ice surface with warm flood water.  Ideally, the flood water will freeze or evaporate quickly after each flood so that skaters can use the ice right away.  Where dehumidification is ineffective, pools of water will remain on the ice for 10 minutes or more, reducing the value of each one-hour time slot.

Mold:  Mold grows wherever water is allowed to condense on surfaces, and is increasingly recognized as a health concern.

Visibility:  Humidity can create a fog which affects visibility.

At present dehumidification is provided by standard direct expansion (DX) dehumidifiers, which are only marginally effective at removing moisture at the temperature maintained in the arena enclosure.  These systems are designed to avoid freeze-up and as a result cannot drop the dew point in the space below about 45°F.  Further, these dehumidifiers are very energy inefficient operating at the temperature and humidity conditions required.  Since the ice sheet is below 30°F, a significant amount of moisture condenses on the ice sheet, adding load to the refrigeration plant.

Retrofit Conditions

We recommend that existing dehumidification be replaced with desiccant dehumidification.  This equipment incorporates a moisture-absorbing chemical (called a desiccant) to remove water from the air.  Because it does not rely on the water condensing on a cold coil surface, there is no risk of equipment freeze-up and it can remove moisture efficiently at low temperatures.

A natural gas burner drives the moisture out of the desiccant so that the moisture is rejected outside and the desiccant is reused.  The added cost of this “regeneration” natural gas is included in savings calculations.  We recommend that the new unit(s) be specified with heat exchangers to recover as much of the regeneration heat as possible.

Further Benefits

This is a superior technology for dehumidifying in a low temperature environment.  It will reduce condensation on interior surfaces, limiting structural deterioration, mold, and slippery floors.  It will eliminate interior fog during warm weather and improve ice quality because water will no longer condense on the ice surface.

Application Details

This retrofit is best considered in the context of capital renewal or improved operation.  It makes the most sense when the existing dehumidification is due for replacement, or where the owner is considering extending the season into the warmer months.  Energy savings alone are unlikely to justify replacement of existing, functioning dehumidification equipment.

Issues and Concerns






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