Acronyms
2-DOF PID	Two-Degree-of-Freedom PID Controller
ABS	Acrylonitrile Butadiene Styrene
ADC	Analogue-to-Digital Converter
AMIGO	Approximate M-constrained Integral Gain Optimization
CC	Cohen–Coon
CHR	Chien–Hrones–Reswick
COP	Coefficient of Performance
DC	Direct Current
EPS	Expanded Polystyrene
IAE	Integral Absolute Error
ISE	Integral Square Error
ITAE	Integral of Time-multiplied Absolute Error
MAE	Mean Absolute Error
MDPM	Multiple Dominant Pole Method
MedAE	Median Absolute Error
MPC	Model Predictive Control
MSE	Mean Squared Error
NTC	Negative Temperature Coefficient
PID	Proportional–Integral–Derivative controller
PLA	Polylactic Acid
PWM	Pulse Width Modulation
RMSE	Root Mean Square Error
SD	Standard Deviation
SIMC	Skogestad Internal Model Control
TV	Total Variation
ZN	Ziegler–Nichols
Symbols
$A$	Internal surface area of the chamber (${\mathrm{m}}^2$)
$C_D$, $C_D^c$, $C_D^h$	Inner-loop PID controllers: general, cooling branch, heating branch
$C_p$	Specific heat of air ($\mathrm{J}·\mathrm{k}{\mathrm{g}}^{-1}·{\mathrm{K}}^{-1}$)
$C_{p_c}$	Specific heat of the module assembly ($\mathrm{J}·\mathrm{k}{\mathrm{g}}^{-1}·{\mathrm{K}}^{-1}$)
$C_T$	Outer-loop PID controller for chamber air temperature
$CO{P}_c$, $CO{P}_h$	Coefficient of performance for cooling and heating
$D$	Duty cycle of the PWM control signal
$D_0$	Duty cycle operating point
$G$	Geometrical factor (area/length) ($\mathrm{m}$)
$G_D$	Transfer function from duty cycle to module temperature
$G_T$	Transfer function from module temperature to chamber air temperature
$I$	Electrical current ($\mathrm{A}$)
$I_{cell}$	Current through the thermoelectric module ($\mathrm{A}$)
$I_{{cell}_0}$	Current through the module operating point ($\mathrm{A}$)
$I_{max}$	Maximum rated current of the module ($\mathrm{A}$)
$K$	Thermal conductance of the module ($\mathrm{W}{\mathrm{K}}^{-1}$)
$K_b$	Anti-windup back-calculation constant
$K_p$	Proportional gain of the PID controller
$k_{\theta }$	Thermal conductivity ($\mathrm{W}{\mathrm{m}}^{-1}{\mathrm{K}}^{-1}$)
$L$, $L^{\prime }$	Transport delay (dead time) in the thermal systems ($\min$)
$m_c$	Lumped mass of the module assembly ($\mathrm{kg}$)
$N_c$	Number of thermoelectric modules
$N_u$	Number of thermocouple pairs in a module
$P_e$	Electrical power input to the module ($\mathrm{W}$)
${\dot{Q}}_c$	Heat absorbed at the cold side of the module ($\mathrm{W}$)
${\dot{q}}_{cell}$	Heat produced or absorbed by a single module ($\mathrm{W}$)
${\dot{Q}}_h$	Heat rejected at the hot side of the module ($\mathrm{W}$)
${\dot{Q}}_{Peltier}$	Ideal Peltier heat flow ($\mathrm{W}$)
$S$	Seebeck coefficient ($\mathrm{V}{\mathrm{K}}^{-1}$)
$s_{\alpha }$	Elemental Seebeck coefficient ($\mathrm{V}{\mathrm{K}}^{-1}$)
$T$	Temperature ($\mathrm{K}$ or $°\mathrm{C}$)
$T_c$	Cold face temperature of the module ($\mathrm{K}$)
$T_{cell}$	Temperature of the module face ($\mathrm{K}$)
$T_{{cell}_0}$	Module temperature operating point ($\mathrm{K}$)
$T_d$	Derivative time of the PID controller ($\min$)
$T_h$	Hot face temperature of the module ($\mathrm{K}$)
$T_{h0}$	Reference module hot-side temperature from datasheet ($\mathrm{K}$)
$T_i$	Integral time of the PID controller ($\min$)
$T_{in}$	Chamber air temperature ($\mathrm{K}$)
$T_{i{n}_0}$	Chamber air temperature operating point ($\mathrm{K}$)
$T_{\infty }$	External ambient temperature ($\mathrm{K}$)
$U$	Overall heat-transfer coefficient of the chamber enclosure ($\mathrm{W}{\mathrm{m}}^{-2}{\mathrm{K}}^{-1}$)
$V$	Internal volume of the chamber (${\mathrm{m}}^3$)
$V_{CC}$	Supply voltage rail for the module ($\mathrm{V}$)
$V_{cell}$	Voltage applied to the module ($\mathrm{V}$)
$V_e$	Electrical voltage ($\mathrm{V}$)
$V_{max}$	Maximum rated voltage of the module ($\mathrm{V}$)
$R$	Electrical resistance of the module ($\mathsf{\Omega }$)
$R^2$	Coefficient of determination
$R_{\theta }$	Effective thermal resistance between modules and chamber air ($\mathrm{K}{\mathrm{W}}^{-1}$)
$\mathsf{\Gamma }$	Gain of module-temperature to air-temperature transfer function ($°\mathrm{C}/°\mathrm{C}$)
$\mathsf{\Delta }T$	Temperature difference ($\mathrm{K}$)
$\mathsf{\Delta }{T}_{max}$	Maximum temperature difference across the module ($\mathrm{K}$)
$\eta$	Derivative filter constant in the PID controller
$\lambda$$, \mu$	Setpoint weighting factors in 2-DOF PID controller
$\nu$	Low-pass filter constant in the Smith predictor
$\mathsf{\Pi }$	Peltier coefficient ($\mathrm{V}$)
$\rho$	Air density ($\mathrm{kg}·{\mathrm{m}}^{-3}$)
${\rho }_e$	Electrical resistivity ($\mathsf{\Omega }\mathrm{m}$)
$\tau$, ${\tau }^{\prime }$	Time constants of the thermal systems ($\min$)
$\mathsf{\Omega }$	Gain of duty-cycle to module-temperature transfer function ($°\mathrm{C}$)