Performance evaluation of cycles
Performance evaluation of cycles: comparisons with the ideal Carnot heat engine that is a totally reversible heat engine or pump.
Q °c T of reservoir (absolute scale)
(1) “Efficiency” (r)) of a Heat Engine
Carnot cycle. "HCamot 1 rp , ^1 Real Process ^ ^1 Carnot
"H Real Process ^ ^
Real irreversibilities:
• Friction, electrical resistance, heat transfer across finite temperature difference, …
(2) “Coefficient of Performance” (COP) of a Heat Pump
Heating conditions (heat pump):
O
Carnot cycle: COPHeat Camot
Cooling conditions (refrigeration): O
T
Carnot cycle: COPCoolCarnot ~——
Th-tl
For energy exchange with the same two thermal reservoirs: O
COP ‘Actual Pump A Carnot |
Carnot efficiency of a heat pump: r
Posted in Fundamentals of Heating. Ventilating, and Air-Conditioning