Electronic pumping of heat without charge transfer

A mechanism of electron-mediated pumping heat in the absence net charge transfer is proposed. It may be realized charge-neutral electron systems, such as graphene, coupled to an external electric potential. The flow this cycle not accompanied by a buildup voltage along system, which offers advantages over traditional thermoelectric cooling setups. efficiency and magnitude flux are studied hydrodynamic regime for weak disorder. shown that approach Carnot limit. In pristine even infinitesimal potential, remains finite. particular, potential form traveling wave moving with velocity $c$, perfect; entire content liquid advected $c$. For general determined geometry disorder strength.