• The previous example illustrates that higher
the temperature of the low-temperature sink, more difficult it becomes for
a heat engine to reject/transfer heat into it.
• This results in a lower thermal
efficiency
• One reason why low-temperature reservoirs
such as rivers, lakes and atmosphere are
popular for heat rejection from power plants.
•
• Similarly, the thermal efficiency of
an engine, e.g a gas turbine engine, can be increased by increasing the
temperature of the combustion chamber.
•This may sometimes
conflict with other design requirements. Example: turbine blades can not withstand high temperature (and
pressure) gases, which can leads to early
fatigue. A Solution: better materials
and/or innovative cooling design.
•