$B$	Buffer space
$C_i$	Heat-leakage coefficient, $\mathrm{W}/\mathrm{K}$
$C_v$	Molar constant volume specific heat capacity, $\mathrm{W}/\mathrm{K}$
$e$	Mechanism effectiveness
$F$	Flywheel
$M$	Mechanical device
$n$	Mole number, $\mathrm{m}\mathrm{o}\mathrm{l}$
$R$	Regenerator
$R_u$	Universal gas constant, $\mathrm{J}/(\mathrm{m}\mathrm{o}\mathrm{l}\cdot \mathrm{K})$
$T$	Temperature, $\mathrm{K}$
$t$	Time duration of the process, $\mathrm{s}$
$V$	Volume, ${\mathrm{m}}^3$
$W_c$	Compression work, J
$W_e$	Expansion work, J
$W_{+}$	Positive piston work, J
$W_{-}$	Negative piston work, J
Greek symbol
$\alpha$, $\beta$	Heat-transfer coefficient, $\mathrm{W}/\mathrm{K}$
$\lambda$	Volume–compression ratio
${\eta }_R$	Efficiency of the regenerator
$\tau$	Cycle period, $\mathrm{s}$
$\sigma$	Entropy-generation rate, $\mathrm{W}/\mathrm{K}$
Subscripts
$opt$	Optimal
Superscripts
$-$	Dimensionless
EP	Efficient power
FTT	Finite time thermodynamics
HT	Heat transfer
HTL	Heat-transfer law
MOO	Multi-objective optimization
OO	Optimization objective
PD	Power density
SHE	Stirling heat engine
WF	Working fluid