• A thermodynamic system is a collection of matter and space with its boundaries defined in such a way that the energy transfer across the boundaries can be best understood.
• Surroundings are everything not in the system being studied.
• Systems are classified into one of three groups:
Isolated system - neither mass nor energy can cross the boundaries
Closed system - only energy can cross the boundaries
Open system - both mass and energy can cross the
boundaries
• A control volume is a fixed region of space that is studied as a thermodynamic system.
• Steady state refers to a condition where the properties at any given point within the system are constant over time. Neither mass nor energy are accumulating within the system.
• A thermodynamic process is the succession of states that a system passes through.
Processes can be described by any of the following terms:
Cyclic process - a series of processes that results in the system returning to its original state
Reversible process - a process that can be reversed resulting in no change in the system or surroundings
Irreversible process - a process that, if reversed, would result in a change to the system or surroundings
Adiabatic process - a process in which there is no heat transfer across the system boundaries
Isentropic process - a process in which the entropy of the system remains unchanged
Polytropic process - the plot of Log P vs. Log V is a straight line, PVn = constant
Throttling process - a process in which enthalpy is constant h1 = h2, work = 0, and which is adiabatic, Q=0.
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