Abstract <p>The operation of a vacuum-pulse drying unit is divided into two stages. The first stage is pumping air out of the receiver. The second stage begins after gas starts flowing into the receiver from the vacuum chamber through the pipeline. The mass flow rate of the gas mixture depends on the pressure at the inlet and outlet of the pipeline. In the work, the load characteristics of the vacuum pump used in the unit are approximated using the spline method. The dependences of productivity and power on the rotor speed are non-monotonic. The purpose of the study is to substantiate the mathematical model of gas-dynamic processes in vacuum-pulse drying of food products. The operation of the liquid-ring vacuum pump ELRS-6 is considered. High rotor speed provides higher vacuum pump performance, while the expended power increases. An increase in the volume of the vacuum chamber leads to an increase in the duration of the second stage at an unchanged volume of the receiver, and the final pressure and mass of air in the operating chamber increase due to the increase in the total volume of the hydraulic system. An increase in the initial pressure in the receiver leads to a decrease in the pressure drop. Therefore, the air flow in the pipeline decreases and the pressure and mass of gas in the vacuum chamber decrease more slowly. An increase in the pipeline diameter leads to a decrease in hydraulic losses and an increase in the mass flow of air in the second stage. With increasing length of the pipeline, hydraulic losses increase and the mass flow of air decreases.</p>