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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 āˆ’1)

d

diameter (m)

g

gravitational acceleration (m2 s āˆ’1)

h

heat transfer coefficient (W m āˆ’2 K āˆ’1)

K

gain (ā€“)

L

inductance (kg m āˆ’4)

l

length (m)

P

pressure (Pa)

p

parameter vector

R

resistance (kg m āˆ’4 s āˆ’1)

\(\dot {S}\)

rate of change of entropy (W K āˆ’1)

s

specific entropy (J kg āˆ’1 K āˆ’1)

 

complex frequency (rad s āˆ’1)

t

time (s)

T

temperature (K)

 

cyclic steady-state period (s)

U

volumetric flowrate (m āˆ’3 s āˆ’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 āˆ’4 s āˆ’1)

Ī±

thermal diffusivity (m2 s āˆ’1)

Ī”

difference

Ī·

thermodynamic efficiency (ā€“)

Ī³

adiabatic index (ā€“)

Īŗ

thermal conductivity (W m āˆ’1 K āˆ’1)

Ī»

eigenvalue

Ī¼

dynamic viscosity (kg m āˆ’1 s āˆ’1)

Ļ

density (kg m āˆ’3)

Ī£

surface area (m2)

Ļ„

reference time (s)

Subscripts and superscripts

\(\hat {\ }\)

dimensionless variable

\(\bar {\ }\)

time-averaged value

L

lower bound

U

upper bound

āˆ˜

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