Volumetric expander, process of starting the volumetric expander, closed-cycle plant, and process for converting thermal energy into electric energy using said plant

A volumetric expander for a closed cycle plant, said volumetric expander comprising:

• at least one casing exhibiting at least one general inlet enabling introduction of a working fluid inside the at least one casing and at least one general outlet enabling expulsion of the working fluid from said at least one casing,
• a piston inside the at least one casing defining a variable volume expansion chamber,
• a main shaft connected to the piston and configured for rotatively moving around a main axis, said main shaft being housed at least partially inside the at least one casing,
• at least one valve configured for selectively opening and closing an inlet and outlet of the expansion chamber enabling at least:
• an introduction condition in which the working fluid is introduced into the expansion chamber,
• an expansion condition in which the working fluid expands in the expansion chamber, and
• a discharge condition in which the working fluid is discharged from said expansion chamber,
• a transmission member connected—on one side—to the at least one valve and—on the other side—to the main shaft, said transmission member being configured for synchronizing the working fluid introduction condition, expansion condition and discharge condition with the rotation of the main shaft,
• wherein the at least one casing internally defines a discharge chamber in direct fluid communication with the at least one general outlet, the discharge chamber being further configured for being put in direct fluid communication with the outlet of the expansion chamber during the discharge condition,
• wherein the transmission member is located in the at least one casing inside the discharge chamber,
• and wherein the at least one casing comprises at least one auxiliary inlet which is only directly in communication with the discharge chamber and, through the discharge chamber, with the at least one general outlet, said at least one auxiliary inlet being not in direct fluid communication with the at least one general inlet and being configured for enabling the working fluid to directly enter the discharge chamber.

A volumetric expander for a closed cycle plant comprising:

• at least one casing exhibiting at least one general inlet enabling introduction of a working fluid inside the at least one casing and at least one general outlet enabling expulsion of the working fluid from said at least one casing,
• a piston housed in said at least one casing defining a variable volume expansion chamber,
• a main shaft connected to the piston and configured for turning around a main axis,
• at least one valve associated with the at least one casing and configured for selectively opening and closing an inlet and outlet of said expansion chamber enabling at least:
• an introduction condition in which the working fluid is introduced into the expansion chamber,
• an expansion condition in which the working fluid expands in the expansion chamber, and
• a discharge condition in which the working fluid is discharged from said expansion chamber,
• wherein the at least one casing internally defines a discharge chamber in direct fluid communication with the at least one general outlet, the discharge chamber being further configured for being put in direct fluid communication with the outlet of the expansion chamber during said discharge condition,
• wherein the at least one casing comprises at least one auxiliary inlet which is in direct communication only with the discharge chamber of the at least one casing and, through the discharge chamber, with the at least one general outlet, the auxiliary inlet being configured for enabling the working fluid to directly enter the at least one casing.