$a$	Proportionality constant in the power law curve fit
$A_o$	Outer surface area of the test tube (m2)
$b$	Power law coefficient (−)
$Bi$	Biot number
$c$	Offset in the power law curve fit (W)
$C_p$	Specific heat (kJ·kg−1·K−1)
$dt$	Elemental change in time (second)
$dT$	Elemental change in temperature (°C)
$h$	Convective heat transfer coefficient (W·m−2·K−1)
$\Delta H$	Step enthalpy change (kJ·kg−1)
$H$	Enthalpy (kJ·kg−1)
$H_f$	Latent heat of fusion (kJ·kg−1)
$H_0$	Reference enthalpy (kJ·kg−1)
$I$	Area under the temperature–time curve (°C-sec)
$k$	Thermal conductivity (W·m−1·K−1)
$m$	Mass (gram)
N	Number of PCM intervals
$q$	Heat flow rate (W)
$R_i$	Inner radius of the test tube (mm)
$R_o$	Outer radius of the test tube (mm)
$R_{th}$	Thermal resistance (°C·W−1)
$t$	Time (second)
$\Delta t$	Duration of the interval (second)
$T$	Temperature (°C)
$\overline{T}$	Average temperature (°C)
$T_m$	Melting temperature (°C)
$T_s$	Solidification temperature (°C)
$T_{SC}$	Supercooling temperature (°C)
$\Delta T$	Step change in temperature (°C)
$\Delta T_{int}$	Minimum allowed temperature interval (°C)
Greek Symbols:
$\epsilon$	Standard uncertainty in temperature measurement (°C)
Subscripts:
$\mathrm{\infty }$	Ambient
$avg$	Average
$cond$	Conduction
$conv$	Convection
$int$	Interval
$l$	Liquid
$m$	Melting point
$pcm$	Phase change material
$ref$	Reference
$s$	Solid
$sen$	Sensor
$tube$	Test tube
Abbreviations:
CFD	Computational fluid dynamics
CMC	Carboxymethyl cellulose
DOE	Department of Energy
DSC	Digital scanning calorimetry
FEA	Finite element analysis
HVAC	Heating, ventilation, and air conditioning
IQR	Interquartile range
JCGM	Joint Committee for Guides in Metrology
PAM	Polyacrylamide
PCM	Phase change material
PDF	Probability density function
SAT	Sodium acetate trihydrate
SLM	Shape language modeling
SPA	Sodium polyacrylate
SSD	Sodium sulfate decahydrate
TES	Thermal energy storage