Electrocaloric cooling: The importance of electric-energy recovery and heat regeneration

Here we explore the effect of electric-energy recovery and heat regeneration on the energy efficiency of an electrocaloric-cooling system. Furthermore, the influence of the polarization-electric field hysteresis on the energy efficiency of the system is analysed. For the purposes of the analysis, the properties of (1 – x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-100xPT) with x = 0, $x=0.1$ , and $x=0.35$ are characterized. We show that if no heat is regenerated, even small irreversibilities in the electric circuit used to recover the electric energy can cause a significant drop in the achievable energy efficiency. On the other hand, when a heat regeneration process is considered and a realistic value for the degree of electric-energy recovery equal to 80% is assumed, the limit for the energy efficiency of a system employing PMN ceramics is estimated to be equal to 81% of the efficiency of a Carnot heat pump