2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/23496$YbInCu_{4}$ and its alloys present discontinuous, first order iso-structural transitions at pressure dependent temperatures $T_V(P)$, where a local moment phase coexist with a renormalized Fermi liquid phase. We show that along the coexistence line $T_V(P)$ the entropy of the large volume renormalized Fermi liquid phase is smaller than that of the higher density, local moment phase. This implies the existence of a Pomeranchuk effect in these Kondo lattice materials in analogy with $^3He$. The theoretical possibility of using these systems as cooling machines is discussed.3 pages, 3 figures and 1 tableStrongly Correlated ElectronsMaterials Sciencetext