Background
According to the physical laws of nature, moisture migrates through
the air from a higher concentration to a lower concentration due to
a difference in vapour pressure. When air is cooled it is not able
to hold as much moisture. Thus moisture will condense on any surface
that has a lower temperature than the dewpoint temperature.
This is a particular problem in Ice Skating rinks
where the condensed moisture is deposited onto the surface of the
ice in the form of water droplets and also in form of fog above
the surface of the ice. When moisture condenses and accumulates
on the surface of the ice, it is known as "Frosting".
This "Frosting" in turn results in "Slow" ice
and also imposes an additional load on the ice making system.
These conditions cannot be solved by ventilation
because introduction of outside air only aggravates the problem
when the weather outside is mild and humid. Insulating the roof
also aggravates drip during mild outside weather conditions. Low
emissivity ceiling stay warmer and thus, reduce condensation and
dripping.
Under these conditions, to prevent condensation
in the ceiling space and to eliminate the fog there are two approaches,
refrigeration or desiccant dehumidification.
Refrigeration
In the past refrigeration air conditioning systems, utilized in
ice skating, hockey and curling rinks, have a history of humidity
related problems as well as high energy consumption. Conventional
refrigeration equipment can maintain space conditions in a skating
rink of 7-15°C (45 to 60 ° F) at a relative humidity of
60% to 75%. This can result in air so close to saturation that it
actually forms a fog over the rink and condensation inside the building
and on the surface of the ice.
Any attempt to maintain lower humidity
levels would necessitate maintaining evaporator temperatures lower
than 32 ° F which results in frost formation on the evaporative
coil. A more effective and energy efficient solution is a desiccant
dehumidification system.
Desiccant Dehumidification
The primary advantage of a desiccant dehumidification system is
its ability to dry air to a very low humidity level. A desiccant
dehumidification system can very easily maintain 30-40 % relative
humidity within the ice skating rink thus, eliminating fog and condensation
year round, regardless of outdoor weather conditions. According
to the studies, conducted by ACCRA and several manufacturers of
desiccant systems, the average energy consumption of a desiccant
dehumidifier is as much as 70% less than that of a comparable refrigeration
system. So, desiccant dehumidification systems can eliminate fog
and condensation while, at the same time, reducing operating costs.
There is also the potential for a reduction in maintenance to the
building and equipment inside as it is no longer subject to excessive
humidity and the problems associated with it.
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