District cooling Technologies
This section describes district cooling systems and the
technologies generally used. These practices are mostly
applicable anywhere, with minor exceptions. For example, thermal storage is
more feasible in locations where electricity tariffs vary from day to day.
A district cooling system has three main components (Figure
2): a cooling source and generating plant, a cooling distribution system, and
an energy transfer station with heat exchangers.
A district cooling system can be part of an upstream system,
either supplying energy to a cooling plant or included in a cogeneration or
trigeneration system. Below are some examples of upstream systems:
·
heating systems
- district heating
- recovery and use of surplus
heat from industry
• electricity generation systems
–
electric power grid
–
electricity generated directly from renewable
energy sources, such as hydro, wind, and solar power
• cogeneration and trigeneration systems
–
CCHP
–
district heating and cooling
Directly or indirectly, the district cooling system can be
based on many different fuels, such as fossil fuels (coal, oil, gas); renewable
energy (biomass, wind, solar, hydro, geothermal energy); and energy from
municipal solid waste and industrial waste. The efficiency of district cooling
technologies, which varies widely, determines the extent of emissions from the
district cooling system, in combination with the fuels used.
a. Cooling Source and Generating Plant
The plant
can be equipped with compressor chillers, heat-driven absorption chillers, or
heat exchangers (for free cooling; see below), or with a combination of these
technologies. The cooling source and the major equipment in the plant will
depend on available resources and their cost, and on local conditions.
In
addition, thermal energy storage will optimize the performance of the chillers,
enable the plant to use cheaper electricity when prices go down, and act as
cooling source during periods of peak demand or provide cooling redundancy and
thereby reduce the required chiller capacity.
Compressor chillers. A compressor chiller is similar to a
heat pump with a compressor, a condenser, an expansion valve, and an
evaporator. Compressor chillers use different types of heat sinks, or passive
heat exchangers (Figure 3). The most common heat sinks for district cooling
projects are air, wastewater, river water, lake water, seawater, groundwater,
and treated sewage water.
Figure 3: compressor chiller
Absorption chillers: An absorption chiller is similar to a
compressor chiller, where the compressor has been replaced by an arrangement of
generator, pump, absorber and absorbent (Figure 4). Instead of a compressor
driven by electricity or steam, the absorption chiller uses hot media—commonly
steam, hot water, or gas—to drive the cycle. Heat sinks used for absorption
chillers are similar to compressor chillers (described above).
figure 4: absorption chiller
www.bilkargroup.com
www.bilkarsogutma.com.tr
info@bilkargroup.com
+90 212 343 50 40
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