integration of solid oxide fuel cells and ... - Ea Energianalyse

1.5. Heat driven cooling
1.5.1 Absorption
There are two major types of absorption cycles:
• Carré cycle which is used for cooling and air conditioning (as well
as heat pumps) in the range of 15 kw to megawatts.
• Platen Munters cycle which is used for small (household size)
refrigerators/freezers.
The two cycles are in principle almost identical, but in practice they
differ a lot - hence the very different applications. In the following
sections, the two types will be described.
1.5.2 Carré cycle
The basic principle of the absorption cycle is developed by the French
scientist Ferdinand Carré about 1860.
Working media.
The fluid in the absorption cycle consists of a pair of a refrigerant and
an absorption medium which is capable to absorb the refrigerant. More
than 40 refrigerants and 200 absorption media exist [35].
The most common pairs are ammonia-water (N H 3 − H 2 O) and waterlithium
bromide (H 2 O − LiBr ). Ammonia is the refrigerant in the N H 3 −
H 2 O solution (ammonia has a lower boiling point than water), whereas
water is the refrigerant in the H 2 O − LiBr solution.
Ammonia-water is usable for small as well as large scale units
working at various temperatures, e.g. air conditioning or industrial
cooling/freezing (evaporator temperatures down to -60 ◦ C).
Water-lithium bromide has a limited temperature range due to the
freezing point of water, and in practical applications the chilled water
should never be lower than 6 ◦ C [27]. Thus this pair is feasible for
applications such as production of chilled water or air conditioning.
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