  Nanodevices consisting of a quantum dot tunnel coupled to one superconducting
and two normal electrodes may serve as a source of entangled electrons. As a
result of crossed Andreev reflection the Cooper pair of s-wave character may be
split into two electrons and each of them goes into a distinct normal
electrode, preserving entanglement. Efficiency of the process depends on the
specific system and is tunable by electric means. Our calculations show that in
the studied device this efficiency may attain values as large as $80 \%$.
