Optimal Design of Thermoelectric Refrigerators Embedded in a Thermal Resistance Network

Thermoelectric refrigeration offers advantages (e.g., no moving parts) over other refrigeration technologies. However, because maximum performance (i.e., heat load for a specified temperature drop below ambient temperature or vice versa) and efficiency (i.e., coefficient of performance) are relatively low, it is important to realize them. It is shown that the cross-sectional area of the semiconductor pellets in a thermoelectric module (TEM) operating in refrigeration mode does not affect its performance or efficiency, but may be sized to tune its operating current and voltage. Then, a procedure is provided to determine the height of the pellets which maximizes performance. Next, it is shown that a range of pellet heights accommodates a specified performance below the maximum one and a procedure is provided to compute that corresponding to maximum efficiency. A thermal resistance boundary condition is applied between the interface in a TEM where Peltier cooling occurs and the control point where it maintains the temperature of a component or medium below ambient temperature. Thermal resistance boundary conditions are also applied between the control point and its local ambient and the interface in a TEM where Peltier heating occurs and its local ambient. The analysis is generalized by using flux-based quantities where applicable and it accounts for the electrical contact resistance at the interconnects in a TEM. Implementation of the optimization procedures are illustrated and the ramifications of the results are discussed.