11.6 Other Air-Conditioning and Heat Pump Cycles
Most residential refrigerators, air-conditioners and heat
pumps operate on the vapor-compression refrigeration cycle. Also, the
air-conditioners used in cars operate on the vapor-compression cycle.
However, in other applications other types of heating and cooling cycles
are used.
11.6.1 Reverse Brayton Cycle
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Just as operating the Rankine cycle with superheat in reverse
leads to the vapor-compression cycle, the Brayton power cycle can
be operated in reverse to yield the reverse
Brayton cycle. The reverse Brayton cycle is commonly used
in aircraft cabin air conditioning systems. Learn more about the
reverse Brayton cycle in Section 11.6.1 in the textbook. |
11.6.2 Reverse Stirling Cycle
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Operating the Stirling power cycle in reverse results in the
reverse Stirling cycle. The reverse
Stirling cycle is commonly used in cryogenic cooling systems. Learn
more about the reverse Brayton cycle in Section 11.6.1 in the textbook. |
11.6.3 Cycles Driven by Heat Transfer
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The refrigeration cycles discussed thus far require a significant
work input, which is most often supplied in the form of electricity
and can result in high operating costs. At many locations, thermal
energy sources are readily available that are significantly less
expensive than electricity. Examples of relatively cheap thermal
energy sources include the combustion of a fuel, the waste heat
from a process or heat engine, and solar energy. This thermal energy
can be used in a refrigeration cycle to reduce or eliminate the
work required by the cycle. Learn more about these cycles in Section
11.6.3 in the textbook.
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