Pumpable ice air conditioning is not a
particularly new technology, but it offers the opportunity to reduce
the operational electric power costs of air conditioning a Data
Center. As part of the same package the technology can provide
standby cooling capability without significantly loading the UPS
while there is a major outage of mains power.
Pumpable ice is a slurry of fine ice
crystals suspended in chilled water. There are several technologies
currently in daily use in the manufacturing and food industries which
generate and store pumpable ice. The same technology is used aboard some fishing vessels to provide cooling to preserve fresh fish. The systems are robust and have an engineering history.
The ice slurry can be stored in large insulated tanks to act as a store of thermal energy for cooling requirements. The ice slurry is approximately five times more efficient at cooling than chilled water, so the pipework involved in transporting pumpable ice can be more narrow than those used for an equivalent chilled water system.
Here's a related Youtube video.
The ice slurry can be stored in large insulated tanks to act as a store of thermal energy for cooling requirements. The ice slurry is approximately five times more efficient at cooling than chilled water, so the pipework involved in transporting pumpable ice can be more narrow than those used for an equivalent chilled water system.
Here's a related Youtube video.
The pumpable ice can be generated
overnight using cheaper off-peak electricity (approx one third of peak day prices) and stored in a thermal
accumulator. The cooler night time air can improve the efficiency of
the ice making process. During the day when electricity is changed at
peak rates the ice slurry can be drawn from the thermal accumulator
to provide a coolant source for the main air conditioning of the
building. This will reduce the use of expensive day-time electricity.
It can also be used to reduce peak loads on the main building water
chillers. Pumpable ice cooling systems can cope with megawatt types
of cooling loads as well as smaller loads. Some ice systems are designed for retro-fitting to existing chiller systems without the risk of compromising existing building chilled water systems.
If the thermal accumulators containing
the ice slurry are of sufficient capacity it is possible to sustain
an extended main chiller outage which could occur in the gap between
a power outage and the successful start up of the building generator.
Some battery backed power would be required to service the pumps for
the pumpable ice. In data centers using energy dense technologies
such as servers and network switches there is a serious risk of
meltdown in a few minutes if coolant is not available. Each equipment
cabinet in the data center might be dumping many kilowatts of heat
load into the confined space of the technology room leading to
serious thermal damage of the equipment. If the standby generator
does not start quickly to power main cooling the results can be
catastrophic.
Oaksys
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