Glossary
- adiabatic process
- a process in which no heat transfer takes place
- Carnot cycle
- a cyclical process that uses only reversible processes, the adiabatic and isothermal processes
- Carnot efficiency
- the maximum theoretical efficiency for a heat engine
- Carnot engine
- a heat engine that uses a Carnot cycle
- change in entropy
- the ratio of heat transfer to temperature
- coefficient of performance
- for a heat pump, it is the ratio of heat transfer at the output (the hot reservoir) to the work supplied; for a refrigerator or air conditioner, it is the ratio of heat transfer from the cold reservoir to the work supplied
- cyclical process
- a process in which the path returns to its original state at the end of every cycle
- entropy
- a measurement of a system's disorder and its inability to do work in a system
- first law of thermodynamics
- states that the change in internal energy of a system equals the net heat transfer into the system minus the net work done by the system
- heat engine
- a machine that uses heat transfer to do work
- heat pump
- a machine that generates heat transfer from cold to hot
- human metabolism
- conversion of food into heat transfer, work, and stored fat
- internal energy
- the sum of the kinetic and potential energies of a system's atoms and molecules
- irreversible process
- any process that depends on path direction
- isobaric process
- constant-pressure process in which a gas does work
- isochoric process
- a constant-volume process
- isothermal process
- a constant-temperature process
- macrostate
- an overall property of a system
- microstate
- each sequence within a larger macrostate
- Otto cycle
- a thermodynamic cycle, consisting of a pair of adiabatic processes and a pair of isochoric processes, that converts heat into work, e.g., the four-stroke engine cycle of intake, compression, ignition, and exhaust
- reversible process
- a process in which both the heat engine system and the external environment theoretically can be returned to their original states
- second law of thermodynamics
- heat transfer flows from a hotter to a cooler object, never the reverse, and some heat energy in any process is lost to available work in a cyclical process
- second law of thermodynamics stated in terms of entropy
- the total entropy of a system either increases or remains constant; it never decreases
- statistical analysis
- using statistics to examine data, such as counting microstates and macrostates