Transient response and Green's function technique

Abstract

This chapter highlights the aspects of transient operation and measurements of thermoelectric (TE) materials and systems. If the timescale of changes in the working or boundary conditions is much greater than the response time of the TE system, a quasi-stationary approach is suitable to describe the transient behavior of the system. A dynamically switched TE cooler can be used to suppress hotspots in electronic chips. Supercooling is reached because there is a temporal and spatial interplay between Peltier cooling (mainly at an interface) and Joule heating as a volume effect. The chapter discusses two different methods for the dynamical determination of the thermal conductivity, namely laser flash analysis and classical Ioffe method. It also demonstrates how the Green's function technique works in the classical theory of thermoelectricity. In addition, the chapter provides the solution to the general formulation of time-dependent heat equation using the reciprocity property and adjoint Green's function.