Methodology for Determining Rational Operating Time for a Reciprocating Displacement Hybrid Energy Machine with Regenerative Heat Exchange in Compressor and Pump Modes

The article presents a methodology for determining rational operating time for a reciprocating displacement hybrid energy machine with regenerative heat exchange in compressor mode while ensuring the maximum indicated efficiency for the full operation cycle and the maximum delivery rate. With the assumption that the cooling time is linearized based on the heating time, it is established that the maximum indicated efficiency is achieved by reducing the operating time while keeping the temperature of the cylinder–piston group at minimal values. It is shown that at maximum efficiency the optimal operating time in compressor mode, taking into account the mode switching time, increases; conversely, it decreases when indicated efficiency decreases.