Thermodynamics
Work, heat and energy systems.
1st Law of Thermodynamics
The First Law of Thermodynamics simply states that energy can be neither created nor destroyed (conservation of energy). Thus power generation processes and energy sources actually involve conversion of energy from one form to another, rather than creation of energy from nothing.
2nd Law of Thermodynamics
Entropy and disorder.
Absorbed Solar Radiation
Solar radiation absorbed by various materials.
Acetone - Thermophysical Properties
Chemical, physical and thermal properties of acetone, also called 2-propanone, dimethyl ketone and pyroacetic acid. Phase diagram included.
Alternative Fuels - Properties
Properties of alternative fuels like biodiesel, E85, CNG and more.
Aluminum - Radiation Heat Emissivity
Radiation heat emissivity of unoxidized, oxidized and polished aluminum.
Ammonia - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculator, figures and tables showing dynamic (absolute) and kinematic viscosity of gasous and liquid ammonia at temperatures ranging from -73 to 425°C (-100 to 800°F) at pressure ranging from 1 to 1000 bara (14.5 - 14500 psia) - SI and Imperial Units.
Ammonia - Prandtl Number vs. Temperature and Pressure
Figures and table with changes in Prandtl number for ammonia with changes in temperature and pressure.
Ammonia - Properties at Gas-Liquid Equilibrium Conditions
Figures and tables showing how the properties of liquid and gaseous ammonia changes along the boiling/condensation curve (temperature and pressure between triple point and critical point conditions). An ammonia phase diagram are included.
Ammonia - Specific Heat vs. Temperature and Pressure
Online calculator, figures and tables showing specific heat, CP and CV, of gasous and liquid ammonia at temperatures ranging from -73 to 425°C (-100 to 800°F) at pressure ranging from 1 to 100 bara (14.5 - 1450 psia) - SI and Imperial Units.
Ammonia - Thermal Conductivity vs. Temperature and Pressure
Online calculator, figures and tables showing thermal conductivity of liquid and gaseous ammonia at temperatures ranging -70 to 425 °C (-100 to 800 °F) at atmospheric and higher pressure - Imperial and SI Units.
Ammonia - Thermophysical Properties
Chemical, Physical and Thermal Properties of Ammonia. Phase diagram included.
Ammonia - Vapour Pressure at Gas-Liquid Equilibrium
Figures and table with ammonia saturation pressure at boiling points, SI and Imperial units.
Ammonia Gas - Density vs. Temperature and Pressure
Online calculator with figures and tables showing density and specific weight of ammonia for temperatures ranging -50 to 425 °C (-50 to 800 °F) at atmospheric and higher pressure - Imperial and SI Units.
Argon - Density and Specific Weight
Online calculator, figures and tables showing density and specific weight of argon, Ar, at varying temperature and pressure - Imperial and SI Units.
Arithmetic and Logarithmic Mean Temperature Difference
Arithmetic Mean Temperature Difference in Heat Exchangers - AMTD - and Logarithmic Mean Temperature Difference - LMTD - formulas with examples - Online Mean Temperature Calculator.
Benzene - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and table showing density and specific weight of benzene, C6H6, at temperatures ranging from 5 to 325 °C (42 to 620 °F) at atmospheric and higher pressure - Imperial and SI Units.
Benzene - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculator, figures and table showing dynamic and kinematic viscosity of benzene, C6H6, at varying temperature and pressure - Imperial and SI Units.
Benzene - Thermophysical properties
Chemical, physical and thermal properties of benzene, also called benzol. Phase diagram included.
Bimetallic Strips
Heat and bending of bimetallic strips.
Building Materials - Radiation Constants
The radiation constant is the product between the Stefan-Boltzmann constant and the emissivity constant for a material.
Butane - Density and Specific Weight vs. Temperature and Pressure
Online calculators, figures and tables showing density and specific weight of liquid and gaseous butane, C4H10, at varying temperarure and pressure, SI and Imperial units.
Butane - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculators, figures and tables with dynamic and kinematic viscosity of liquid and gaseous butane, C4H10, at varying temperarure and pressure, SI and Imperial units.
Butane - Specific Heat vs. Temperature and Pressure
Online calculators, figures and tables showing specific heat, Cp and Cv, of gasous and liquid butane, C4H10, at varying temperarure and pressure, SI and Imperial units.
Butane - Thermal Conductivity vs. Temperature and Pressure
Online calculators, figures and tables showing thermal conductivity of liquid and gaseous butane, C4H10, at varying temperature and pressure, SI and Imperial units.
Carbon dioxide - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of carbon dioxide, CO2, at temperatures ranging from -50 to 775 °C (-50 to 1400 °F) at atmospheric and higher pressure - Imperial and SI Units.
Carbon Dioxide - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculator, figures and table showing dynamic and kinematic viscosity of carbon dioxide, CO2, at varying temperature and pressure - Imperial and SI Units.
Carbon dioxide - Prandtl Number vs. Temperature and Pressure
Figures and table with changes in Prandtl number for carbon dioxide with changes in temperature and pressure.
Carbon dioxide - Thermal Conductivity vs. Temperature and Pressure
Online calculator, figures and table showing thermal conductivity of carbon dioxide, CO2, at temperatures ranging from -50 to 775 °C (-50 to 1400 °F) at atmospheric and higher pressure - Imperial and SI Units.
Carbon Dioxide - Thermophysical Properties
Chemical, physical and thermal properties of carbon dioxide. Phase diagram included.
Carbon Monoxide - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of carbon monoxide, CO, at varying temperature and pressure - Imperial and SI Units.
Carnot Efficiency
The efficiency of the Carnot cycle.
Combustion Heat
Heat of combustion (energy content) for som common substances - with examples how to calculate heat of combustion.
Conductive Heat Transfer
Conductive heat transfer takes place in a solid if there is a temperature gradient.
Convective Heat Transfer
Heat transfer between a solid and a moving fluid is called convection. This is a short tutorial about convective heat transfer.
Cooling Mode - Heat Flux
Heat fluxes for various cooling or heat transfer modes.
Critical Points for some Substances
Critical points of some common substances like air, argon, helium and more
Critical Temperatures and Pressures for some Common Substances
Critical temperatures and pressures for some common substances like air, alcohol, ether, oxygen and more.
Dowtherm A
Physical properties of Dowtherm A.
Efficiency
Efficiency is the ratio useful energy output to energy input.
Emissivity Coefficients common Products
The radiation heat transfer emissivity coefficients for some common materials like aluminum, brass, glass and many more.
Energy
Energy is the capacity to do work.
Energy Accumulated in Heated Water - kWh
The amount of thermal energy stored in heated water.
Energy Conversion Factors
Convert between energy units
Energy Storage Density
Energy density - by weight and volume - for some ways to store energy
Energy Transfer Equation
Fluid energy transfer.
Ethane - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of ethane, C2H6, at varying temperature and pressure - Imperial and SI Units.
Ethane - Thermal Conductivity vs. Temperature and Pressure
Online calculator, figures and table showing thermal conductivity of ethane, C2H6, at varying temperature and pressure - Imperial and SI Units.
Ethanol - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculator, figures and tables showing dynamic and kinematic viscosity of ethanol, C2H5OH, at varying temperature and pressure - Imperial and SI Units.
Ethanol - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of ethanol at temperatures ranging from -25 to 325 °C (-10 to 620 °F) at atmospheric and higher pressure - Imperial and SI Units.
Ethanol - Specific Heat vs. Temperature and Pressure
Online calculators, figures and tables showing specific heat , Cp and Cv, of gasous and liquid ethanol at temperatures ranging from -25 to 325 °C (-10 to 620 °F) at atmospheric and higher pressure - Imperial and SI Units.
Ethanol - Thermophysical properties
Chemical, physical and thermal properties of ethanol (also called alcohol or ethyl alcohol). Phase diagram included.
Ethylene - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of ethylene, C2H4, at varying temperature and pressure - Imperial and SI Units.
Ethylene - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculator, figures and tables showing dynamic and kinematic viscosity of ethylene, C2H4, also called ethene or acetene, at varying temperature and pressure - Imperial and SI Units.
Ethylene - Thermal Conductivity vs. Temperature and Pressure
Online calculator, figures and table showing thermal conductivity of ethylene, also called ethene or acetene, C2H4, at varying temperature and pressure - Imperial and SI Units.
Ethylene - Thermophysical Properties
Chemical, physical and thermal properties of ethylene, also called ethene, acetene and olefiant gas. Phase diagram included.
Fluid Heat Transfer Coefficients in Heat Exchanger Surface Combinations
Average overall heat transmission coefficients for fluid and surface combinations like Water to Air, Water to Water, Air to Air, Steam to Water and more.
Food and Foodstuff - Specific Heat
Specific heat of common food and foodstuff like apples, bass, beef, pork and many more.
Freezing Mixtures and Cooling Agents
Freezing mixtures, cooling agents and freezing points.
Gases - Specific Heats and Individual Gas Constants
Specific heat at constant volume, specific heat at constant pressure, specific heat ratio and individual gas constant - R - common gases as argon, air, ether, nitrogen and many more.
Gases Solved in Water - Diffusion Coefficients
Diffusion flux [kg/m2s] tells how fast a substanse solved in another substance flows due to concentration gradients. Diffusion constants [m2/s] for several gases in water.
Heat Capacity
The amount of heat required to change the temperature of a substance by one degree.
Heat Exchanger Materials - Thermal Conductivities
Typical heat exchanger materials and their thermal conductivities.
Heat Exchangers - Fouling and Reduced Heat Transfer
Heat-transfer in heat exchangers are reduced by fouling.
Heat Exchangers - Heat Transfer Coefficients
Overall heat transfer coefficients in common heat exchanger designs - tubular, plate or spiral.
Heat, Work and Energy
Heat vs. work vs. energy.
Heating Up Applications - Energy Required and Heat Transfer Rates
Energy required to heat up a substance.
Heavy Water - Thermophysical Properties
Thermodynamic properties of heavy water (D2O) like density, melting temperature, boiling temperature, latent heat of fusion, latent heat of evaporation, critical temperature and more.
Helium - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of helium, He, at varying temperature and pressure - Imperial and SI Units.
High and Low Heat Values
The gross (high) and net (low) heating values.
Hydrogen - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of hydrogen, H2, at temperatures ranging from -260 to 325 °C (-435 to 620 °F) at atmospheric and higher pressure - Imperial and SI Units.
Hydrogen - Thermal Conductivity vs. Temperature and Pressure
Online calculator, figures and table showing thermal conductivity of hydrogen, H2, at varying temperature and pressure - Imperial and SI Units.
Hydrogen sulfide - Thermophysical Properties
Chemical, physical and thermal properties of hydrogen sulfide, H2S, also called hydrosulfuric acid, sewer gas and stink damp. Phase diagram included.
Ice and Water - Melting Points vs. Pressure
Online calculator, figures and tables with melting points of ice to water at pressures ranging from 0 to 29000 psia (0 to 2000 bara). Temperature given as °C, °F, K and °R.
Latent Heat of Melting for some common Materials
Latent heat of fusion when changing between solid or liquid state for common materials like aluminum, ammonia, glycerin, water and more.
Linear Thermal Expansion
Online linear temperature expansion calculator.
Liquid Ammonia - Thermal Properties at Saturation Pressure
Density, specific heat, thermal conductivity, viscosity and Prandtls no. of liquid ammonia at saturation pressure.
Liquids - Densities vs. Pressure and Temperature Change
Densities and specific volume of liquids vs. pressure and temperature change.
Liquids - Freezing and Melting Points
Common fluids and their freezing and melting points.
Liquids - Thermal Conductivities
Some fluids and their thermal conductivities.
Liquids - Volumetric Expansion Coefficients
Volumetric - or cubical - expansion coefficients for common liquids.
Liquids and Fluids - Specific Heats
Specific heats for some common liquids and fluids - acetone, oil, paraffin, water and many more.
Metals - Specific Heats
Specific heat of commonly used metals like aluminum, iron, mercury and many more - imperial and SI units.
Methane - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculator, figures and tables showing dynamic and kinematic viscosity of methane, CH4, at varying temperature and pressure - Imperial and SI Units.
Methane - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of methane, CH4, at temperatures ranging from -160 to 725 °C (-260 to 1300 °F) at atmospheric and higher pressure - Imperial and SI Units.
Methane - Prandtl number vs. Temperature
Figures and table showing changes in Prandtl number for methane with changes in temperature and pressure.
Methane - Thermal Conductivity vs. Temperature and Pressure
Online calculator, figures and table showing thermal conductivity of methane, CH4, at temperatures ranging from -160 to 725 °C (-260 to 1300 °F) at atmospheric and higher pressure - Imperial and SI Units.
Methane - Thermophysical Properties
Chemical, Physical and Thermal Properties of Methane - CH4. Phase diagram included.
Methanol - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of methanol,CH3OH, at varying temperature and pressure - Imperial and SI Units.
Methanol - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculator, figures and tables showing dynamic and kinematic viscosity of liquid methanol,CH3OH, at varying temperature - Imperial and SI Units.
Methanol - Specific Heat vs. Temperature and Pressure
Online calculator, figures and tables showing isobaric and isochoric specific heat of methanol, CH3OH, at varying temperature - Imperial and SI Units.
Methanol - Thermophysical Properties
Chemical, physical and thermal properties of methanol, CH3OH (also called carbinol, wood alcohol, hydroxy methyl and methyl alcohol). Phase diagram included.
Microwave Heating
Heating with microwaves.
Mixing Liquids and/or Solids - Final Temperatures
Calculate the final temperature when liquids or solids are mixed
Mollier Chart for Water - Imperial Units
Mollier chart for water in English Units
Mollier Chart for Water - Metric Units
Mollier chart for water in Metric Units
Nitrogen - Enthalpy, Internal Energy and Entropy vs. Temperature
Enthalpy, internal energy and entropy of Nitrogen as an ideal gas.
Nitrogen - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of nitrogen, N2, at temperatures ranging from -175 to 1325 °C (-280 to 2400 °F) at atmospheric and higher pressure - Imperial and SI Units.
Nitrogen - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculator, figures and tables showing dynamic and kinematic viscosity of nitrogen, N2, at varying temperature and pressure - Imperial and SI Units.
Nitrogen - Prandtl number vs. Temperature and Pressure
Figures and tables showing Prandtl number of nitrogen at varying temperarure and pressure, SI and Imperial units.
Nitrogen - Thermal Conductivity vs. Temperature and Pressure
Online calculator, figures and tables showing thermal conductivity of nitrogen, N2, at varying temperarure and pressure, SI and Imperial units.
Nitrogen - Thermal Diffusivity vs. Temperature and Pressure
Figures and tables showing thermal diffusivity of nitrogen at varying temperarure and pressure, SI and Imperial units.
Nitrogen - Thermophysical Properties
Chemical, Physical and Thermal Properties of Nitrogen - N2.
Overall Heat Transfer Coefficients
Walls or heat exchangers - calculate overall heat transfer coefficients.
Oxygen - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of oxygen, O2, at varying temperature and pressure - Imperial and SI Units.
Oxygen - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculator, figures and tables showing dynamic and kinematic viscosity of oxygen, O2, at varying temperature and pressure - Imperial and SI Units.
Pentane - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and table showing density and specific weight of pentane, C5H12, at temperatures ranging from -130 to 325 °C (-200 to 620 °F) at atmospheric and higher pressure - Imperial and SI Units.
Pentane - Thermophysical Properties
Chemical, physical and thermal properties of pentane, also called n-pentane. Phase diagram included.
Piping Materials - Temperature Expansion Coefficients
Temperature expansion coefficients for materials used in pipes and tubes like aluminum, carbon steel, cast iron, PVC, HDPE and more.
Power Plants - Performance Efficiencies
Power plants heat rates, thermal efficiencies, capacity factors, load factors, economic efficiencies, operational efficiencies and energy efficiencies.
Propane - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of propane, C3H8, at temperatures ranging from -187 to 725 °C (-305 to 1300 °F) at atmospheric and higher pressure - Imperial and SI Units.
Propane - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculators, figures and tables showing dynamic and kinematic viscosity of liquid and gaseous propane at varying temperarure and pressure, SI and Imperial units.
Propane - Prandtl Number vs. Temperature and Pressure
Figures and tables with Prandtl Number of liquid and gaseous propane at varying temperarure and pressure, SI and Imperial units.
Propane - Specific Heat vs. Temperature and Pressure
Online calculators, figures and tables with specific heat, Cp and Cv, of gasous and liquid propane, C3H8 vs. temperature and pressure - Imperial and SI Units .
Propane - Thermal Conductivity vs. Temperature and Pressure
Online calculator, figures and tables showing thermal conductivity of liquid and gaseous propane at varying temperarure and pressure, SI and Imperial units.
Propane - Thermal Diffusivity vs. Temperature and Pressure
Figures and tables showing thermal diffusivity of liquid and gaseous propane at varying temperarure and pressure, SI and Imperial units.
Property vs. State
The concept of properties and state.
Radiation Emissivity Coefficients
Radiation emissivity of common materials like water, ice, snow, grass and more.
Radiation Heat Transfer
Heat transfer due to emission of electromagnetic waves is known as thermal radiation.
Rankine Efficiency
The efficiency of the Rankine cycle.
Salt Hydrates - Melting points and Latent Energy
Melting points and latent energy of salt hydrates.
Solids - Specific Heats
Common solids - like brick, cement, glass and many more - and their specific heats - in Imperial and SI units.
Solids - Volume Temperature Expansion Coefficients
Cubical expansion coefficients for solids.
Solids, Liquids and Gases - Thermal Conductivities
Thermal conductivity coefficients for insulation materials, aluminum, asphalt, brass, copper, steel, gases and more.
Specific Heat - Online Unit Converter
Online specific heat converter with the most commonly used units.
Specific Heat of common Substances
Specific heat of products like wet mud, granite, sandy clay, quartz sand and more.
Standard enthalpy of formation, Gibbs energy of formation, entropy and molar heat capacity of organic substances
The standard enthalpy of formation, Gibbs energy of formation, entropy and molar heat capacity are tabulated for more than hundred organic substances.
Standard State and Enthalpy of Formation, Gibbs Free Energy of Formation, Entropy and Heat Capacity
Definition and explanation of the terms standard state and standard enthalpy of formation, with listing of values for standard enthalpy and Gibbs free energy of formation, as well as standard entropy and molar heat capacity, of 370 inorganic compounds.
Standardized Enthalpies and Entropies
Standardized enthalpies and entropies for some common substances.
Storing Thermal Heat in Materials
Energy stored as sensible heat in materials.
Surface Radiation Absorptivity
Radiation surface absorptivity.
Symbols Used to Denote a Chemical Reactions and Process or Condition
Explanation of symbols used as subscripts or superscripts to tell more about the type of chemical reaction, process or condition.
Temperature
Introduction to temperature - including Celsius, Fahrenheit, Kelvin and Rankine definitions - and an online temperature converter.
Thermal Conductivity - Online Converter
Convert between thermal conductivity units.
Thermal Conductivity - Unit Converting Table
Convert between thermal conductivity units - table and diagram.
Thermal Expansion - Linear Expansion Coefficients
Linear temperature expansion coefficients for common materials like aluminum, copper, glass, iron and many more.
Thermal Expansion - Superficial i.e. Area
Superficial i.e area temperature expansion - online calculator.
Thermal Resistivity and Conductivity
The ability of a material to resist flow of heat.
Thermal Transmittance vs. Thermal Resistance
The thermal transmittance U vs. the thermal resistance R.
Thermodynamic Key Values Internationally Agreed
Internationally agreed, internally consistent, values for the thermodynamic properties (standard enthalpy of formation, entropy and [H°(298)-H°(0)]) of key chemical substances.
Thermodynamic Terms - Functions and Relations
Common thermodynamic terms and functions - potential energy, kinetic energy, thermal or internal energy, chemical energy, nuclear energy and more.
Third Law of Thermodynamics
The entropy of a substance is zero if the absolute temperature is zero.
Toluene - Density and Specific Weight vs. Teemperature and Pressure
Density and specific weight of liquid toluene.
Toluene - Thermophysical Properties
Chemical, physical and thermal properties of toluene, also called methylbenzene, toluol and phenylmethane. Phase diagram included.
Units of Heat - BTU, Calorie and Joule
The most common units of heat BTU - British Thermal Unit, Calorie and Joule.
Volumetric (Cubic) Thermal Expansion
Volumetric temperature expansion calculator.
WABT - Weighted Average Bed Temperature
Definition and examples of calculation of weighted average bed temperature in adiabatic reactors.
Water - Boiling Points at Vacuum Pressure
Online calculator, figures and tables giving the boiling temperatures of water in varying vacuum, SI and Imperial units.
Water - Enthalpy (H) and Entropy (S) vs. Temperature
Figures and tables showing the enthalpy and entropy of liquid water as function of temperature - SI and Imperial Units.
Water - Heat of Vaporization vs. Temperature
Online calculator, figures and tables showing heat of vaporization of water, at temperatures from 0 - 370 °C (32 - 700 °F) - SI and Imperial units.
Water - Ionization Constant, pKw, of Normal and Heavy water
Ionization constant (= dissociation constant = self-ionization constant = ion product = autoprotolysis constant ) of water and heavy water, given as function of temperature (°C and °F) in figures and tables.
Water - Prandtl Number vs. Temperature and Pressure
Figures and tables with Prandtl Number of liquid and gaseous water at varying temperarure and pressure, SI and Imperial units.
Water - Properties at Gas-Liquid Equilibrium Conditions
Figures and tables showing how the properties of water changes along the boiling/condensation curve (vapor pressure, density, viscosity, thermal conductivity, specific heat, Prandtl number, thermal diffusivity, entropy and enthalpy).
Water - Specific Gravity vs. Temperature
Figures and tables showing specific gravity of liquid water in the range of 32 to 700 °F or 0 to 370°C, using water density at four different temperatures as reference.
Water - Specific Heat vs. Temperature
Online calculator, figures and tables showing specific heat of liquid water at constant volume or constant pressure at temperatures from 0 to 360 °C (32-700 °F) - SI and Imperial units.
Water - Thermal Conductivity vs. Temperature
Figures and tables showing thermal conductivity of water (liquid and gas phase) with varying temperature and pressure, SI and Imperial units.
Water - Thermal Diffusivity vs. Temperature and Pressure
Figures and tables with thermal diffusivity of liquids and gaseous water at varying temperarures and pressures - SI and Imperial units.
Water Boiling Points at Higher Pressures
Online calculator, figures and tables showing boiling points of water at pressures ranging from 14.7 to 3200 psia (1 to 220 bara). Temperature given as °C, °F, K and °R.
Water vs. Steam - Critical and Triple Points
Critical point is where vapor and liquid are indistinguishable and triple point is where ice, water and vapor coexist in thermodynamic equilibrium.
Water-Steam Mollier Diagram
Enthalpy-entropy diagram for water and steam.
Work done by Force
Work done by a force acting on an object.
Zeroth Law of Temperature
The direction of heat flow.