20 terms

Thermo final

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Terms in this set (...)

What is energy?
ability to cause change
Define an intensive property; and give two examples
does not depend on mass in a system; temperature, density
Define an equilibrium state.
a state of no unbalanced potentials
What is another name for the 1st law of thermodynamics?
Conservation of energy
What two forms of energy interaction can a closed system have?
heat work
What is a pure substance?
substance with one chemical composition throughout
What is a closed system?
no mass transfer across system boundary
What is the boundary work for a constant volume process?
0
The compressed liquid approximation requires modification for accuracy for what variable?
enthalpy
What types of problems include an accumulation term for the conservation equations?
unsteady
Why are throttling valves considered adiabatic?
there is not enough space or time for significant heat transfer
What is a heat engine?
a device that converts heat to work
What is a thermal reservoir?
any large body with a high thermal energy whose temperature does not change when heat is added or taken out
What are the two ways to have an isentropic process?
adiabatic and reversible, remove entropy by heat or mass to counter Sgen
In addition to minimizing irreversibilities, how can we minimize the work required by a compressor?
cool it
What is latent heat?
heat that is produced or absorbed for changes in state
In what phases are temperature and pressure not dependent on each other?
compressed liquid, super heated vapor
For a cycle, the change in energy of the system is equal to what?
0
For what type of substance are the specific heats (cv and cp) equal to each other?
incompressible
What does enthalpy physically represent (for all types of processes)?
h=u+Pv