Gas turbines work on a constant-volume cycle, so power output
depends on air mass flow. Warm air is less dense than cold air,
so power output is reduced. Also, warm air needs more energy to
compress it than cold air, removing more work from the
compressor, increasing internal losses as it does so. The work
required by the compressor can be 66% of the total turbine
power. Therefore, gas turbine efficiency can be improved by
cooling the inlet air. This is especially effective in hot, dry
climates. A significant benefit of turbine air inlet cooling is
that it can reduce (or eliminate) fuel efficiency reduction by
evaporative cooling the inlet air to the wet bulb temperature.
However, note that over-cooling past the wet bulb temperature by
chilling will increase power but with little or no net
efficiency improvement. An increase in inlet air temperature
from 15°C to 38°C increases the heat rate, which causes a
decrease in fuel efficiency of about 4%. Turbine air inlet
cooling can minimize this loss. In a gas turb