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Table 1 Nomenclature

From: Optimization-based investigations of a two-phase thermofluidic oscillator for low-grade heat conversion

A cross-section area (m2)
C capacitance (m4 s2 kg −1)
d diameter (m)
g gravitational acceleration (m2 s −1)
h heat transfer coefficient (W m −2 K −1)
K gain (–)
L inductance (kg m −4)
l length (m)
P pressure (Pa)
p parameter vector
R resistance (kg m −4 s −1)
\(\dot {S}\) rate of change of entropy (W K −1)
s specific entropy (J kg −1 K −1)
  complex frequency (rad s −1)
t time (s)
T temperature (K)
  cyclic steady-state period (s)
U volumetric flowrate (m −3 s −1)
V volume (m3)
\(\dot {W}\) work power (W)
\(\dot {X}\) thermal exergy power (W)
x state vector
y position of vapor-liquid interface (m)
Z impedance (kg m −4 s −1)
α thermal diffusivity (m2 s −1)
Δ difference
η thermodynamic efficiency (–)
γ adiabatic index (–)
κ thermal conductivity (W m −1 K −1)
λ eigenvalue
μ dynamic viscosity (kg m −1 s −1)
ρ density (kg m −3)
Σ surface area (m2)
τ reference time (s)
Subscripts and superscripts
\(\hat {\ }\) dimensionless variable
\(\bar {\ }\) time-averaged value
L lower bound
U upper bound
reference or equilibrium value
0 initial value
ad adiabatic vapor chamber
d displacer cylinder
ex exergetic
f feedback connection
gl glass
l load
p power cylinder
pf pumped fluid
sat fluid in saturation region
th thermal domain
tl thermal loss
vap vapor
wf working fluid