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SWAC - SEA WATER AIR CONDITIONING
Sea Water Air Conditioning (SWAC)
takes
advantage of available deep cold
seawater instead of energy-intensive refrigeration systems to
cool the chilled water in one or more buildings.
The single most effective
measure for reducing carbon dioxide emissions on a global basis would
be the substitution of deep ocean water air conditioning and industrial
cooling wherever and whenever it is feasible. But 'hard headed'
business persons who do not give a fig for 'global warming concerns'
are economically 'soft headed' if, for profit making reasons, they do
not install deep ocean water cooling systems whenever and wherever
feasible. For once the "bootleggers and the ministers" can cooperate
for the benefit of humanity. Here in 'cold hard print' is a paper from
Makai Ocean Engineering Company that tells it like it is from an
economic standpoint. The global warming implications are not mentioned
but are obvious...
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It is economical and environmentally
friendly:
• renewable energy
source
• energy efficient - saves more than 90% of the
energy used for conventional air conditioning
• proven technology
• decreased reliance on fossil fuels - reduced air
pollution, acid rain, global warming
• short economic payback period
• cost effective over the long term - twice the life
of chillers coupled with a significant energy cost savings
• cost are nearly independent of future energy price
increases
• cold seawater availability for secondary
applications
• reduction in fresh water use compared to
conventional A/C systems.
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 Auxiliary
Chiller: In some cases, it may be either too costly or
impractical to supply seawater at the necessary low temperatures to
maintain minimum temperatures in the chilled water loop. The distance
offshore to reach sufficiently cold water might be prohibitive or the
ocean depth may simply not be available. It is sometimes economically
possible to use auxiliary chillers to supplement the cooling provided
by the seawater exposure. This is illustrated to the left. The fresh
chilled water is first cooled by seawater through a heat exchanger and
then secondarily cooled with an auxiliary chiller. The auxiliary
chiller is basically a refrigeration system with its condenser cooled
by the returning flow of cool seawater. With the condenser kept cool,
the auxiliary chiller can operate at an extremely high efficiency – as
high as double that of a conventional chiller.
Cold Storage: A SWAC system
has a high capital cost and a
low
operating cost. The peak capacity of the system must match the peak
demand of the buildings that it serves. These demands are not constant
throughout the day or throughout the year, and the total system is
frequently not being used to its maximum capacity. Therefore, capital
dollars are spent on a system that may not always be used to its
maximum potential. A means of minimizing the capital cost is to use
cold-water storage. The seawater air conditioning system would be
operated 100 percent of the time and when the building demands are low,
the excess capacity is directed into a storage system of cold fresh
water. When A/C demand is at its peak, the cold water is drained from
its storage to meet the demand.
Cold water storage tanks
are commercially available that are constant
volume; the warm water remains at the top and the coldest water remains
at the bottom. These tanks are now used in conjunction with
conventional A/C systems to take advantage of low, off-peak electrical
rates.
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