From 98ee2b861a5761e0cfd8aeae89a4857cc680c16c Mon Sep 17 00:00:00 2001 From: Alvie Rahman Date: Thu, 23 Dec 2021 17:28:35 +0000 Subject: [PATCH] add notes on mmme/1048 thermodynamics lecture 1 --- .../thermodynamics.md | 153 ++++++++++++++++++ 1 file changed, 153 insertions(+) create mode 100755 uni/mmme/1048_thermodynamics_and_fluid_mechanics/thermodynamics.md diff --git a/uni/mmme/1048_thermodynamics_and_fluid_mechanics/thermodynamics.md b/uni/mmme/1048_thermodynamics_and_fluid_mechanics/thermodynamics.md new file mode 100755 index 0000000..65fa9c9 --- /dev/null +++ b/uni/mmme/1048_thermodynamics_and_fluid_mechanics/thermodynamics.md @@ -0,0 +1,153 @@ +--- +author: Alvie Rahman +date: \today +title: MMME1048 // Thermodynamics +tags: [ uni, nottingham, mechanical, engineering, mmme1048, thermodynamics ] +--- + +# What is Thermodynamics? + +Thermodynamics deals with the transfer of heat energy and temperature. + +# Concepts and Definitions + +## System + +A region of space, marked off by its boundary. +It contains some matter and the matter inside is what we are investigating. + +There are two types of sysems: + +- Closed systems + + - Contain a fixed quantity of matter + - Work and heat cross bounaries + - Impermeable boundaries, some may be moved + - Non-flow processes (no transfer of mass) + +- Open systems + + - Boundary is imaginary + - Mass can flow in an out (flow processes) + - Work and heat transfer can occur + +## Equilibrium + +The system is in equilibrium if all parts of the system are at the same conditions, such as pressure +and temperature. + +The system is not in equilibrium if parts of the system are at different conditions. + +#### Adiabatic + +A process in which does not cross the system boundary + +## Properties of State + +*State* is defined as the condition of a system as described by its properties. +The state may be identified by certain observable macroscopic properties. +These properties are the *properties of state* and they always have the same values for a given +state. + +A *property* can be defined as any quantity that depends on the *state* of the system and is +independant of the path by which the system arrived at the given state. +Properties determining the state of a thermodynamic system are referred to as *thermodynamic +properties* of the *state* of the system. + +Common properties of state are: + +- Temperature +- Pressure +- Mass +- Volume + +And these can be determined by simple measurements. +Other properties can be calculated: + +- Specific volume +- Density +- Internal energy +- Enthalpy +- Entropy + +### Intensive vs Extensive Properties + +In thermodynamics we distinguish between *intensive*, *extensive*, and *specific* properties: + +- Intensive --- properties which do not depend on mass (e.g. temperature) +- Extensive --- properties which do depend on the mass of substance in a system (e.g. volume) +- Specific (extensive) --- extensive properties which are reduced to unit mass of substance + (essentially an extensive property divided by mass) (e.g. specific volume) + +## Units + +Property | Symbol | Units | Intensive | Extensive +--------------- | ------ | --------------- | --------- | --------- +Pressure | p | Pa | Yes | +Temperature | T | K | Yes | +Volume | V | m$^3$ | | Yes +Mass | m | kg | | Yes +Specific Volume | $\nu$ | m$^3$ kg$^{-1}$ | Yes | +Density | $\rho$ | kg m$^{-3}$ | Yes | +Internal Energy | U | J | | Yes +Entropy | S | J K$^{-1}$ | | Yes +Enthalpy | H | J | | Yes + +## Thermodynamic Processes and Cycles + +When a thermodynaic system changes from one state to another it is said to execute a *process*. +An example of a process is expansion (volume increasing). + +A *cycle* is a process or series of processes in which the end state is identical to the beginning. +And example of this could be expansion followed by a compression. + +### Reversible and Irreversible Proccesses + +During reversible processes, the system undergoes a continuous succession of equilibrium states. +Changes in the system can be defined and reversed to restore the intial conditions + +All real processes are irreversible but some can be assumed to be reversible, such as controlled +expansion. + +### Constant _____ Processes + +#### Isothermal + +Constant temperature process + +#### Isobaric + +Constant pressure process + +#### Isometric / Isochoric + +Constant volume process + +## Heat and Work + +Heat and Work are different forms of enery transfer. + +They are both transient phenomena and systems never possess heat or work. +Both represent energy crossing boundaries when a system undergoes a change of state. + +By convention, the transfer of energy into the system from the surroundings is positive. + +### Heat + +*Heat* is defined as: + +> The form of energy that is transferred across the boundary of a system at a given temperature to +> another system at a lower temperature by virtue of the temperature difference between the two + +### Work + +*Work* is defined as: + +$$W = \int\! F \mathrm{d}x$$ + +(the work, $W$, done by a force, $F$, when the point of application of the force undergoes a +displacement, $\mathrm dx$) + +# Process and State Diagrams + +Reversible processes are represented by solid lines, and irreversible processes by dashed lines.