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uni/mmme/1048_thermodynamics_and_fluid_mechanics/thermodynamics.md
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uni/mmme/1048_thermodynamics_and_fluid_mechanics/thermodynamics.md
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---
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author: Alvie Rahman
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date: \today
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title: MMME1048 // Thermodynamics
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tags: [ uni, nottingham, mechanical, engineering, mmme1048, thermodynamics ]
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---
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# What is Thermodynamics?
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Thermodynamics deals with the transfer of heat energy and temperature.
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# Concepts and Definitions
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## System
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A region of space, marked off by its boundary.
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It contains some matter and the matter inside is what we are investigating.
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There are two types of sysems:
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- Closed systems
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- Contain a fixed quantity of matter
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- Work and heat cross bounaries
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- Impermeable boundaries, some may be moved
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- Non-flow processes (no transfer of mass)
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- Open systems
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- Boundary is imaginary
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- Mass can flow in an out (flow processes)
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- Work and heat transfer can occur
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## Equilibrium
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The system is in equilibrium if all parts of the system are at the same conditions, such as pressure
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and temperature.
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The system is not in equilibrium if parts of the system are at different conditions.
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#### Adiabatic
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A process in which does not cross the system boundary
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## Properties of State
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*State* is defined as the condition of a system as described by its properties.
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The state may be identified by certain observable macroscopic properties.
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These properties are the *properties of state* and they always have the same values for a given
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state.
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A *property* can be defined as any quantity that depends on the *state* of the system and is
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independant of the path by which the system arrived at the given state.
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Properties determining the state of a thermodynamic system are referred to as *thermodynamic
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properties* of the *state* of the system.
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Common properties of state are:
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- Temperature
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- Pressure
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- Mass
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- Volume
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And these can be determined by simple measurements.
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Other properties can be calculated:
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- Specific volume
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- Density
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- Internal energy
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- Enthalpy
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- Entropy
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### Intensive vs Extensive Properties
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In thermodynamics we distinguish between *intensive*, *extensive*, and *specific* properties:
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- Intensive --- properties which do not depend on mass (e.g. temperature)
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- Extensive --- properties which do depend on the mass of substance in a system (e.g. volume)
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- Specific (extensive) --- extensive properties which are reduced to unit mass of substance
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(essentially an extensive property divided by mass) (e.g. specific volume)
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## Units
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Property | Symbol | Units | Intensive | Extensive
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--------------- | ------ | --------------- | --------- | ---------
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Pressure | p | Pa | Yes |
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Temperature | T | K | Yes |
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Volume | V | m$^3$ | | Yes
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Mass | m | kg | | Yes
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Specific Volume | $\nu$ | m$^3$ kg$^{-1}$ | Yes |
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Density | $\rho$ | kg m$^{-3}$ | Yes |
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Internal Energy | U | J | | Yes
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Entropy | S | J K$^{-1}$ | | Yes
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Enthalpy | H | J | | Yes
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## Thermodynamic Processes and Cycles
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When a thermodynaic system changes from one state to another it is said to execute a *process*.
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An example of a process is expansion (volume increasing).
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A *cycle* is a process or series of processes in which the end state is identical to the beginning.
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And example of this could be expansion followed by a compression.
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### Reversible and Irreversible Proccesses
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During reversible processes, the system undergoes a continuous succession of equilibrium states.
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Changes in the system can be defined and reversed to restore the intial conditions
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All real processes are irreversible but some can be assumed to be reversible, such as controlled
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expansion.
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### Constant _____ Processes
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#### Isothermal
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Constant temperature process
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#### Isobaric
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Constant pressure process
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#### Isometric / Isochoric
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Constant volume process
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## Heat and Work
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Heat and Work are different forms of enery transfer.
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They are both transient phenomena and systems never possess heat or work.
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Both represent energy crossing boundaries when a system undergoes a change of state.
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By convention, the transfer of energy into the system from the surroundings is positive.
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### Heat
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*Heat* is defined as:
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> The form of energy that is transferred across the boundary of a system at a given temperature to
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> another system at a lower temperature by virtue of the temperature difference between the two
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### Work
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*Work* is defined as:
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$$W = \int\! F \mathrm{d}x$$
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(the work, $W$, done by a force, $F$, when the point of application of the force undergoes a
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displacement, $\mathrm dx$)
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# Process and State Diagrams
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Reversible processes are represented by solid lines, and irreversible processes by dashed lines.
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