Methods to Evaluate and Measure Power of Pneumatic System and Their Applications

Chinese Journal of Mechanical Engineering

Table 1 Symbols and units

Description	Symbol	Dimension⁽¹⁾	Practical units
Pneumatic available energy per unit mass of air	e	L²T⁻²	J/kg
Pneumatic available energy	E	ML²T⁻²	J
Enthalpy per unit mass of air	h	L²T⁻²	J/kg
Pneumatic power	P	ML⁻¹T⁻²	W
Air mass	m	M	kg
Absolute pressure (equal to the relative pressure plus the atmospheric pressure)	p	ML⁻¹T⁻²	Pa⁽²⁾
Pressure drop	Δp	ML⁻¹T⁻²	Pa
Mass flow-rate	q _m	MT⁻¹	kg/s
Volume flow-rate at standard conditions	q _v	L³T⁻¹	m³/s
Gas constant (for a perfect gas)	R ⁽³⁾	L²T⁻²Θ⁻¹	J/(kg·K)
Entropy per unit mass of air	s	L²T⁻²Θ⁻¹	J/(kg·K)
Thermodynamic temperature	T	Θ	K
Velocity	u	LT⁻¹	m/s
Volume	V	L³	m³
Mechanical work	W	ML²T⁻²	J
Isobaric specific heat	c _p	L²T⁻²Θ⁻¹	J/(kg·K)
Specific heat ratio	κ ⁽⁴⁾	Dimensionless parameter
Efficiency	η	Dimensionless parameter