Dryer operating method

A method for operating a dryer, the dryer including a heating device, a tumbler that is configured to receive an object to be dried and that is connected to an exit of the heating device, a fan connected to an exit of the tumbler, a heat exchanger connected to an exit of the fan through a first flow line that is configured to carry a working fluid, a compressor having (i) an entrance connected to a circulation line including the first flow line connected to the exit of the fan and (ii) an exit connected to an entrance of the heat exchanger, a discharge valve connected to an exit of the heat exchanger, a discharge line connected to the exit of the heat exchanger and to the discharge valve, a regeneration line that is branched from the discharge line and connected to the circulation line, and a control valve disposed at the regeneration line, the method comprising:

• operating the heating device to thereby heat the working fluid;
• based on operating compressor, discharging a portion of the working fluid in the circulation line to an outside of the circulation line to thereby reduce a pressure of the working fluid in the tumbler;
• operating the tumbler to thereby dry the object in the tumbler;
• operating the control valve to control flow of the working fluid from the regeneration line to the circulation line;
• and
• cooling the object in the tumbler.