In this communication, the concept of bottom flashing under the mechanical heat pump system is introduced in the batch distillation columns. Proposing an operating strategy at transient state, a numerical control mechanism is formulated to simultaneously adjust the following variables aiming to ensure the optimal use of internal heat source: flow rate of reboiler liquid subjected to bottom flashing, operating pressure of throttling valve, compression ratio for pressure adjustment in the isentropic compressor and external heat input to the reboiler. The potential of this novel energy efficient batch distillation is numerically quantified in terms of the two performance indexes, namely energy savings and cost. Finally, a binary system is dynamically simulated to demonstrate the proposed configuration. (C) 2016 Elsevier Ltd. All rights reserved.