  Thermoelectric (TE) air cooling is a solid-state technology that has the
potential to replace conventional vapor compression-based air conditioning. In
this paper, we present a detailed system-level modeling for thermoelectric air
conditioning system with position-dependent (graded) and constant material
properties. Strategies for design optimization of the system are provided in
terms of cost-performance trade-off. Realistic convection heat transfer at both
sides of the system are taken into account in our modeling. Effects of
convection heat transfer coefficients, air flowrate, and thermoelectric
material properties are investigated with varying key parameters such as TE leg
thickness, module fill factor, and input current. Both constant material
properties and graded properties are considered for the TE materials, and they
are compared in terms of the degree of cooling, coefficient of performance
(COP), and power consumption. For graded materials, we employ one-dimensional
finite element methods to solve the coupled electrical and thermal current
equations with arbitrary profile of material properties varying with position
along the TE legs. We find that graded materials can enhance the degree of
cooling, but only at the expense of COP, compared to the case of constant
property materials. With constant material properties of ZT = 1 and relatively
low electric current, the power consumption of TE cooler can be lower than
those of conventional air conditioners at an equivalent cooling capacity.
Considering additional advantages such as demand-flexible operation, low noise,
and high scalability, thermoelectric cooling could be a competitive technology
for future air conditioning applications.
