# An introduction to thermodynamics

## This doc aims to help you master thermodynamics. It gives you an overview of the subject and is useful for beginners and experts.

higher education
education
teaching
physics
laws of thermodynamics
teaching materials

# An introduction to thermodynamics

## higher education, education, teaching, physics, laws of thermodynamics, teaching materials

An introduction to thermodynamics

Basic algorithm of thermodynamics (BAT) and its applications

Zhigang Suo

Professor of Mechanics and Materials, Harvard University

Email: [email protected]

This book aims to help you master thermodynamics. I will keep updating the book. Please access the current version online. The book is written as a google doc. If you have the google doc app on your phone, pad, and computer, your copy of the book will always be synced with mine.

This book describes an approach to teaching thermodynamics, which I call the basic algorithm of thermodynamics (BAT). The approach is not new, but I have not seen it described clearly elsewhere. This approach does not center on the “laws of thermodynamics”, but on the steps of using thermodynamics. For teachers, I have outlined this approach in the first chapter, entitled The Play of Thermodynamics.

Also see a shorter version of this book: a review of thermodynamics

The play of thermodynamics

The cast

Thermodynamics for everyone

History

Ignore the laws

Postulates and facts

Big data

Logic, intuition, and application are distinct aspects of thermodynamics

Intuition

Application

logic

Basic algorithm of thermodynamics (BAT)

Pattern of application

Concrete examples

Reviews of books on thermodynamics and statistical physics

Ideal gas

Air

Atom and molecule

An experimental setup

What is temperature?

Ideal gas law

Boltzmann constant

Gas constants, universal and specific

Partial pressure of a species of molecules in an ideal gas mixture

Relative humidity

Moist air

Saturated vapor pressure

Relative humidity

The number of H2O molecules in a bottle of air

Dew point

Ice and water

Phase

State

Property

Temperature-energy curve

Energy of melting

Thermal capacity

Water and steam

Specific volume

An experimental setup to study water and steam

Temperature-volume plane

Process

Liquid-gas dome

Critical state

Rule of mixture

Many functions of two variables

Steam tables and steam apps

Inside the dome

Outside the dome

Pressure-volume plane

Temperature-pressure plane

Ice, water, and steam

Three-phase equilibrium

Experimental observations of three-phase equilibrium

Rule of three-phase mixture

Water expands on freezing

Temperature-volume plane

Pressure-volume-temperature surface

Pressure-volume plane

Temperature-pressure plane

Energy-volume plane

Three types of thermodynamic planes

Three phases of carbon dioxide

Isolated system

Energy, space, matter, and charge

System

A system interacts with its surroundings

Isolated system

An isolated system conserves energy, space, matter, and charge

A classification of systems

Energy

Potential energy

Definition of energy

Kinetic energy

Thermal energy (internal energy)

Electrical energy

Chemical energy

Energy belongs to many sciences

Measurement of internal energy function and energy transfer

Change in energy of several forms

Experimental determination of the internal energy of a closed system as a function of state

Experimental determination of the energy transfer from the fire to the fluid

Energy transfer depends on process

Constant-volume process

Constant-pressure process. Enthalpy

Transfer energy in various ways

Work and heat

Transfer energy by work

Transfer energy by heat

Sign convention

Misuse of the word heat

Work and heat are superfluous ideas in thermodynamics

The first law of thermodynamics

Internal energy of an ideal gas

Thermal capacity of an ideal gas

Energy transfer by work and by heat

Constant-volume process

Constant-pressure process

Isothermal process

Entropy

Sample space

Sample space of an isolated system

Definition of entropy

Entropy is a thermodynamic property

Entropy is extensive

Entropy is dimensionless

Entropy is absolute

Absolute, dimensionless entropies per molecule of H2O at various thermodynamic states

Numbers of quantum states per molecule in ice, water, and steam

Basic algorithm of thermodynamics (BAT)

Fundamental postulate of the statistics of an isolated system

Random variable

Ignorance is bliss

Dispersion of ink

Separation of phases

Subsystems

Constraint internal to an isolated system

Internal variable

Equilibrium

Reversibility

Irreversibility

Fluctuation

Kinetics

Basic algorithm of thermodynamics (BAT)

The second law of thermodynamics

Thermal system

Entropy and energy

A family of isolated systems of a single independent property

Energy-entropy plane

Common features of the function S(U)

Phrases associated with a family of isolated systems

Dissipation of energy

BAT on thermal contact

Definition of temperature

The zeroth law of thermodynamics

Features of the function T(U) common to all thermal systems

Thermal capacity

Calorimetry

Thermometry

Count the number of quantum states of an isolated system experimentally

Debye model

Theory of melting

Model melting using a thermal system

Primitive curves

A mixture of two homogeneous states

A mixture of any number of homogeneous states

Convex hull

Derived curve

Equilibrium of a single homogeneous state

Equilibrium of two homogeneous states

Equilibrium of three homogenous states does not exist in a thermal system

Temperature-entropy curve

Thermal system of a nonconvex characteristic function s(u)

Metastability

Thermal environment

Temperature as an independent variable

Thermostat

Thermal reservoir

A thermal system in a thermal environment

Partial equilibrium

Massieu function

Helmholtz function

Melting analyzed using the Helmholtz function

Closed system

A family of isolated systems of two independent variables

Energy-volume plane

Energy-volume-entropy space

Constant-volume process

Experimental determination of the function S(U,V) of a closed system

BAT on two closed systems in contact

Features of the function S(U,V) common to all closed systems

Thermal capacity

Theory of ideal gas

Ideal gas law derived

Energy of an ideal gas

Enthalpy of an ideal gas

Entropy of an ideal gas

Summary of equations of ideal gas

Entropic elasticity

Theory of osmosis

Theory of pure substance

Primitive surfaces

Rule of mixture

Derived surface

Equilibrium of a single homogeneous state

Equilibrium of two homogeneous states

Equilibrium of three homogeneous states

Equilibrium of four homogeneous states is impossible for a pure substance

Critical state

Metastability

Energy-volume plane

Temperature and pressure

Alternative independent properties

Entropy S(U,V)

Energy U(S,V)

Enthalpy H(S,P)

A closed system and a weight together constitute a thermal system

Enthalpy of a closed system

H(S,P) is a characteristic function of a closed system

Thermal capacity of a closed system in a constant-pressure process

Helmholtz function F(T,V)

Helmholtz function F(T,V) is a characteristic function of a closed system

Maxwell relation

Increment of the function U(T,V)

Increment of the function S(T,V)

A closed system in a thermal environment

Massieu function

Gibbs function G(T,P)

Gibbs function G(T,P) is a characteristic function of a closed system

Other mathematical relations

A closed system in a thermomechanical environment

Planck function

Free entropy vs free energy

Equilibrium of two homogeneous states by equating the Gibbs function

Clapeyron equation

Breed thermodynamic relations like rabbits

Van der Waals model of liquid-gas phase transition

Equation of state, P(T,V)

Critical state

Helmholtz function

Entropy

Energy

Competition between entropy and energy

Maxwell rule

From ideal gas to real fluid, multicomponent materials, and materials genome

Fossil-fueled civilization

Steam engine

Generator

From sunlight to electricity—an indirect route

From sunlight to electricity—a direct route

Energy flow chart

Rejected energy

Carnot cycle

Carnot question

Carnot engine

BAT on an engine

Reversible work

Energy efficiency

Carnot efficiency

Entropy efficiency

Entropy generation

Entropic price

Exergy

Carnot refrigerator

Produce mechanical energy using a thermal system and environment

Produce mechanical energy using a closed system and environment

Motion of a fluid

Control volume

Energy transfer at inlet and exit

Diabatic turbine

Compressor

Condenser

Nozzle

Throttle

Heat exchanger

Slides: engine and refrigerator

Ideal gas mixture

Thermodynamic states of an ideal gas mixture

Volume of an ideal gas mixture

Sliding semipermeable boxes

Energy of an ideal gas mixture

Enthalpy of an ideal gas mixture

Entropy of an ideal gas mixture

Entropy of mixing

Psychrometrics

Psychrometric state

Psychrometric chart

Psychrometric property

Psychrometric process

Open system

A family of isolated systems of many independent variables

Definition of chemical potentials

Temperature vs. chemical potential

BAT on two open systems in contact

Experimental determination of the chemical potential of a species of molecules in an open system

No litter

Gibbs function

Binary system

Unfinished business of collecting big data

Homogeneous function

Chemical potentials of molecules in simple systems

Pure substance

Incompressible pure substance

Pure ideal gas

Ideal gas mixture

Electronic nose

Relative humidity

The ascent of sap

The cost of an invasion

Transpiration pulls liquid water up

The tensile stress in xylem at the top of a tree

BAT on a tree

Mechanical, thermal, and chemical environment

Thermochemical environment

An open system in mechanical, thermal, and chemical environment

Partial equilibrium

Work

Chemical reaction

Stoichiometry

Absolute entropy

Conservation of energy

Change of enthalpy in several processes

BAT on a reaction

Enthalpy-entropy conflict

Fuel cell

Lithium ion batteries

Theoretical air

Dew point

Energy tr

An introduction to thermodynamics
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