Carnot cycle |
cycle that consists of two isotherms at the temperatures of two reservoirs and two adiabatic processes connecting the isotherms |
Carnot engine |
Carnot heat engine, refrigerator, or heat pump that operates on a Carnot cycle |
Carnot principle |
principle governing the efficiency or performance of a heat device operating on a Carnot cycle: any reversible heat device working between two reservoirs must have the same efficiency or performance coefficient, greater than that of an irreversible heat device operating between the same two reservoirs |
Clausius statement of the second law of thermodynamics |
heat never flows spontaneously from a colder object to a hotter object |
coefficient of performance |
measure of effectiveness of a refrigerator or heat pump |
cold reservoir |
sink of heat used by a heat engine |
disorder |
measure of order in a system; the greater the disorder is, the higher the entropy |
efficiency (e) |
output work from the engine over the input heat to the engine from the hot reservoir |
entropy |
state function of the system that changes when heat is transferred between the system and the environment |
entropy statement of the second law of thermodynamics |
entropy of a closed system or the entire universe never decreases |
heat engine |
device that converts heat into work |
heat pump |
device that delivers heat to a hot reservoir |
hot reservoir |
source of heat used by a heat engine |
irreversibility |
phenomenon associated with a natural process |
irreversible process |
process in which neither the system nor its environment can be restored to their original states at the same time |
isentropic |
reversible adiabatic process where the process is frictionless and no heat is transferred |
Kelvin statement of the second law of thermodynamics |
it is impossible to convert the heat from a single source into work without any other effect |
perfect engine |
engine that can convert heat into work with 100%100% efficiency |
perfect refrigerator (heat pump) |
refrigerator (heat pump) that can remove (dump) heat without any input of work |
refrigerator |
device that removes heat from a cold reservoir |
reversible process |
process in which both the system and the external environment theoretically can be returned to their original states |
third law of thermodynamics |
absolute zero temperature cannot be reached through any finite number of cooling steps |