Apparatus, comprising: a container, configured to receive material to be dried and having a container inlet and a container outlet; a pump that is configured to motivate a first air-vapor mixture flow from a first heat exchanger via the container inlet through said material and via the container outlet before it flows into said container via said container inlet; a heating device that is configured to heat said first air-vapor mixture; a selector with at least two states: in a first state it directs most of the said first air-vapor mixture to flow from said container outlet to said container inlet in a closed cycle; and in its second state it exchanges most of the said first air-vapor mixture with air located outside the apparatus, and enables to transfer part of the heat from said first air-vapor mixture toward a fluid located outside the apparatus; characterised by: a compressor that is configured to compress and motivate a part of said first air-vapor mixture flow as a second air-vapor mixture flow to flow through said first heat exchanger; a second heat exchanger is configured to remove excess heat from air-vapor mixture toward outside of the apparatus; a pressure reducing device that is configured to reduce the pressure of said second air-vapor mixture downstream said first heat exchanger wherein: said first heat exchanger is configured to transfer heat between said compressed second air-vapor mixture and said first air-vapor mixture. a container, configured to receive material to be dried and having a container inlet and a container outlet; a pump that is configured to motivate a first air-vapor mixture flow from a first heat exchanger via the container inlet through said material and via the container outlet before it flows into said container via said container inlet; a heating device that is configured to heat said first air-vapor mixture; a selector with at least two states: in a first state it directs most of the said first air-vapor mixture to flow from said container outlet to said container inlet in a closed cycle; and in its second state it exchanges most of the said first air-vapor mixture with air located outside the apparatus, and enables to transfer part of the heat from said first air-vapor mixture toward a fluid located outside the apparatus; in a first state it directs most of the said first air-vapor mixture to flow from said container outlet to said container inlet in a closed cycle; and in its second state it exchanges most of the said first air-vapor mixture with air located outside the apparatus, and enables to transfer part of the heat from said first air-vapor mixture toward a fluid located outside the apparatus; characterised by: a compressor that is configured to compress and motivate a part of said first air-vapor mixture flow as a second air-vapor mixture flow to flow through said first heat exchanger; a second heat exchanger is configured to remove excess heat from air-vapor mixture toward outside of the apparatus; a pressure reducing device that is configured to reduce the pressure of said second air-vapor mixture downstream said first heat exchanger wherein: said first heat exchanger is configured to transfer heat between said compressed second air-vapor mixture and said first air-vapor mixture. a compressor that is configured to compress and motivate a part of said first air-vapor mixture flow as a second air-vapor mixture flow to flow through said first heat exchanger; a second heat exchanger is configured to remove excess heat from air-vapor mixture toward outside of the apparatus; a pressure reducing device that is configured to reduce the pressure of said second air-vapor mixture downstream said first heat exchanger wherein: said first heat exchanger is configured to transfer heat between said compressed second air-vapor mixture and said first air-vapor mixture.