Thermodynamic Properties

Vocabulary flashcards covering key thermodynamic concepts, pure substances, working fluids, units, and enthalpy from Claire Yu Yan's Introduction to Engineering Thermodynamics.

Pure substance

A matter that has a homogeneous composition; it may exist in a single phase (such as liquid water, ice, and $CO_2$ gas) or as a multi-phase mixture (such as liquid water and water vapour).

Homogeneous mixture

A mixture where the different components are uniformly combined, such as salt dissolved in water, creating a single, consistent substance.

Heterogeneous mixture

A mixture where the components remain separate, such as sand and water.

Air (in thermal appliances)

A mixture of oxygen, nitrogen, and a small amount of other gases that serves as a common working matter and is considered a pure substance in most cases.

Working fluid

A pure substance or refrigerant (such as water in steam plants, or R134a and R32 in refrigerator or AC plants) whose properties, like pressure and temperature, continuously change as it flows through cycle devices.

Thermodynamic tables

Tables commonly used to determine the thermodynamic properties of a pure substance.

Bar to MPa conversion factor

$$1\,\text{bar} = 0.1\,\text{MPa}$$

Enthalpy ($H$)

A thermodynamic property that essentially tells the total energy content of a system, measured in units of energy such as joules ($\text{J}$) or kilojoules ($\text{kJ}$).

Enthalpy Change ($\Delta H$)

A thermodynamic measure that indicates the heat transferred into or out of a system at constant pressure.

Specific enthalpy ($h$)

The enthalpy per unit mass of a system, expressed in units of $\text{J/kg}$.

Spirax Sarco

An online calculator suggested for finding thermodynamic steam properties, such as specific enthalpy dependent on steam temperature and pressure.