The possibility of enhancing the thermoelectric figure of merit ZT by damping the material thermal conductivity (e.g. by quantum confinement) rather than by increasing its power factor has generated a surge of interest toward the use of nanostructures in thermoelectric generators (TEGs). Actually, while ZT is an appropriate performance index when optimizing the rate of heat conversion in the presence of small thermal power inputs, it may turn out to be misleading when used as a general criterion. Under fixed heat flow conditions, the optimization of ZT may actually proceed only by maximizing the power factor, since materials with low κ may be unable to duly dissipate heat. However, also when operating between heat reservoirs at fixed temperature it is shown that the highest electric power a TEG can output may be obtained by increasing κ, not decreasing it. In addition, it will be presented an equation allowing to determine the TE efficiency over temperature ranges where transport parameters are no longer temperature-independent. © 2012 American Institute of Physics.
Narducci, D. (2012). Electric power output optimization in Seebeck generators: Beyond high ZT. In K.M. Paraskevopoulos, E. Hatzikraniotis (a cura di), 9th European Conference on Thermoelectrics (ECT2011), Thessaloniki, Greece, September 28-30, 2011 (pp. 532-535). American Institute of Physics [10.1063/1.4731611].
Electric power output optimization in Seebeck generators: Beyond high ZT
NARDUCCI, DARIO
2012
Abstract
The possibility of enhancing the thermoelectric figure of merit ZT by damping the material thermal conductivity (e.g. by quantum confinement) rather than by increasing its power factor has generated a surge of interest toward the use of nanostructures in thermoelectric generators (TEGs). Actually, while ZT is an appropriate performance index when optimizing the rate of heat conversion in the presence of small thermal power inputs, it may turn out to be misleading when used as a general criterion. Under fixed heat flow conditions, the optimization of ZT may actually proceed only by maximizing the power factor, since materials with low κ may be unable to duly dissipate heat. However, also when operating between heat reservoirs at fixed temperature it is shown that the highest electric power a TEG can output may be obtained by increasing κ, not decreasing it. In addition, it will be presented an equation allowing to determine the TE efficiency over temperature ranges where transport parameters are no longer temperature-independent. © 2012 American Institute of Physics.
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