Exhaust gas energy recovery system

A volumetric fluid expander for an engine, the engine having an intake manifold and an exhaust manifold, the expander comprising:

• a housing having an inlet port and an outlet port, the inlet port in fluid communication with the exhaust manifold and configured to receive a first exhaust stream from the exhaust manifold, and the outlet port in fluid communication with the intake manifold and configured to discharge a second exhaust stream, the second exhaust stream having a lower pressure or temperature than the first exhaust stream;
• a plurality of meshed rotors disposed in the housing and configured to expand the first exhaust stream into the second exhaust stream;
• and
• an output shaft operatively connected to one of the plurality of rotors and rotated by the exhaust to generate a mechanical work as the exhaust undergoes expansion through the plurality of rotors within the housing.

A generator for a volumetric fluid expander, the volumetric fluid expander comprising:

• a housing having an inlet port and an outlet port, the inlet port in fluid communication with an exhaust manifold of an internal combustion engine and configured to receive a first exhaust stream from the exhaust manifold, and the outlet port in fluid communication with an intake manifold of the engine and configured to discharge a second exhaust stream, the second exhaust stream having a lower pressure or temperature than the first exhaust stream;
• a plurality of meshed rotors disposed in the housing and configured to expand the first exhaust stream into the second exhaust stream;
• and
• an output shaft operatively connected to one of the plurality of rotors and rotated by the exhaust to generate a mechanical work as the exhaust undergoes expansion through the plurality of rotors within the housing,
• wherein the generator is configured to control a rotational speed of the rotors to adjust an amount of the second exhaust stream discharged from the housing of the volumetric fluid expander.

An exhaust gas energy recovery system comprising:

• a. a power plant having an exhaust gas outlet for conveying an exhaust gas stream at a first pressure;
• and
• b. a volumetric fluid expander including:
• i. a housing having an inlet and an outlet, the housing inlet being in fluid communication with the exhaust gas outlet;
• ii. an output shaft;
• c. wherein the volumetric fluid expander is configured to generate useful work at the output shaft by expanding the exhaust gas stream to a second pressure lower than the first pressure generally without reducing the volume of the exhaust stream as the exhaust stream moves from the housing inlet to the outlet, wherein the volumetric fluid expander includes:
• a. first and second twisted meshed rotors rotatably disposed in the housing, wherein the rotors have an equal number of lobes, and wherein the lobes of the first rotor do not contact the lobes of the second rotor.