Cooling of electrons up to ultra-low temperatures is a long-standing problem in mesoscopic and quantum physics. Usually phonons are cooled down, and electrons are expected to have a similar temperature. However, this is often not the case, and the temperature of electrons can be by significantly higher than the one of phonons. In this work, we study theoretically a process of cooling electrons using a superconducting tunnel junction with a π phase difference and a usual insulator or a ferroelectric in-between, and an array of such junctions with ferroelectric layers in-between. These setups have a complex structure of entropy due to nodal lines, where the density of states can be divergent or larger than for a free electron gas at a chemical potential level. We consider a small current running from the bath of electrons through the setup, where electrons have to have higher entropy, and thus remove heat from the bath.