Patent Description:
Some systems, such as unmanned aerial vehicles (UAV's) or the like often utilize electrical power for propulsion and operation of onboard systems. Some such systems, such as medium-sized UAV's that require power levels in the range of about <NUM> KW to <NUM> KW, have relatively short mission times because the energy density of batteries is far too low to effectively work in this power range, and conventional internal combustion engines and jet engines are very inefficient at these low power levels. One option that has been developed is a tethered UAV system in which the UAV is connected to a power source on the ground by a tether. Use of a tethered UAV allows for an increase in mission duration time, but reduces an operating height and distance in which the UAV may operate, due to the constraint of the tether. An untethered efficient power source that is lightweight with a high power density is greatly desired. <CIT> relates to a multi-shaft reheat turbine mechanism for generating power. <CIT> relates to a gas turbine plant.

According to one embodiment, an electrical power generation system is provided. The electrical power generation system including a micro-turbine alternator. The micro-turbine alternator including a combustor, a first stage turbine configured to be driven by a combustor exhaust from the combustor, at least one compressor operably connected to the combustor to provide a compressed airflow to the combustor, a catalytic converter configured convert the combustor exhaust to a catalytic exhaust that includes at least exothermic heat, a second stage turbine configured to be driven by the catalytic exhaust from the catalytic converter, and one or more shafts connecting the first stage turbine and the second stage turbine to the at least one compressor such that rotation of the first stage turbine and the second stage turbine drives rotation of the at least one compressor.

An exhaust turbine reheat cycle is configured to transfer heat from the combustor exhaust entering the first stage turbine to the combustor exhaust entering the catalytic converter.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the exhaust turbine reheat cycle further includes a heat exchanger including one or more heat rejection passageways and one or more heat absorption passageways.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the exhaust turbine reheat cycle further includes a first passageway extending from the combustor to the one or more heat rejection passageways and fluidly connecting the combustor to the one or more heat rejection passageways.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the exhaust turbine reheat cycle further includes a second passageway extending from the one or more heat rejection passageways to the first stage turbine and fluidly connecting the one or more heat rejection passageways to the first stage turbine.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the exhaust turbine reheat cycle further includes a third passageway extending from the first stage turbine to the one or more heat absorption passageways and fluidly connecting the first stage turbine to the one or more heat absorption passageways.

In addition to one or more of the features described above, or as an alternative, further embodiments may include a fourth passageway extending from the one or more heat absorption passageways to the catalytic converter and fluidly connecting the one or more heat absorption passageways to the catalytic converter.

In addition to one or more of the features described above, or as an alternative, further embodiments may include a fifth passageway extending from the catalytic converter to the second stage turbine and fluidly connecting the catalytic converter to the second stage turbine.

In addition to one or more of the features described above, or as an alternative, further embodiments may include a sixth passageway extending from the second stage turbine to a turbine of an auxiliary turbo charger and fluidly connecting the second stage turbine to the turbine.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the one or more heat absorption passageways are thermally connected to the one or more heat rejection passageways.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the one or more heat absorption passageways are physically connected to the one or more heat rejection passageways.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the at least one compressor further includes a first stage compressor and a second stage compressor located aft of the first stage compressor. The first stage compressor and the second stage compressor being operably connected to the combustor to provide the compressed airflow to the combustor.

In addition to one or more of the features described above, or as an alternative, further embodiments may include an electric generator disposed along the one or more shafts such that electrical power is generated via rotation of the one or more shafts. The electric generator is disposed along the one or more shafts between the first stage compressor and the second stage compressor.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that at least one of the one or more shafts passes through the electric generator.

According to another embodiment a vehicle is provided. The vehicle including a propulsion system and an electrical power generation system operably connected to the propulsion system. The electrical power generation system including a micro-turbine alternator. The micro-turbine alternator including a combustor, a first stage turbine configured to be driven by a combustor exhaust from the combustor, at least one compressor operably connected to the combustor to provide a compressed airflow to the combustor, a catalytic converter configured convert the combustor exhaust to a catalytic exhaust that includes at least exothermic heat, a second stage turbine configured to be driven by the catalytic exhaust from the catalytic converter, and one or more shafts connecting the first stage turbine and the second stage turbine to the at least one compressor such that rotation of the first stage turbine and the second stage turbine drives rotation of the at least one compressor.

As previously noted, an untethered, lightweight, high power density power source would allow systems like UAVs to have longer mission times without the height and distance limits of a tether. A prior approach to power generation involves micro-turbine alternator designs that places the electric generator at a forward end of a rotating shaft upstream of the compressor and turbine, which are then both located at an aft end of a rotating shaft. With this type of arrangement, the rotational speed of the compressor is limited by the compressor inlet relative velocity as the inlet diameter of the compress hub is increased to accommodate the rotating shaft that connects the compressor hub to the electric generator. Further, with this type of arrangement the compressor and turbine are overhung on the aft end of the rotating shaft, thus reducing the critical speed of the overall assembly. Embodiments disclosed herein relate to an interstage electric alternator for micro-turbine alternator applications. The micro-turbine alternator according to one or more embodiments may be used in a UAV or electrically-powered suit, as discussed for explanatory purposes, or any electrically-powered system. The design places an electric generator between two stages of the compressor to reduce the inlet diameter of the first stage compressor hub to as close to zero as possible so that the micro-turbine alternator may provide more power and operate with a lower inlet pressure.

Embodiments disclosed herein utilized a combustor to drive the turbine, rotating shaft, and compressor. Compressed air from the compressor is fed into the combustor and then fuel is added to the air and ignited.

In conventional combustor systems, with ignition the temperature of the air is raised up to a desired inlet temperature of a turbine. This compressed and heated air then enters the turbine inlet. The air enters the turbine at approximately a high temperature, which is near the thermal limit of the material used to manufacture the turbine. As the air passes through the turbine, it expands and cools, transferring energy to the turbine blades, causing the turbine to rotate. In a single stage turbine, the temperature of the air that leaves the turbine is still fairly high, resulting in energy leaving the engine, without doing useful work. This leads to a reduced engine efficiency.

Embodiments disclosed herein seek to make use of the aforementioned additional energy that left the engine. The embodiments disclosed herein accomplish this by utilizing a multi-stage turbine with an integrated re-heat cycle. Advantageously, using a two-stage turbine allows the engine to operate at higher rotational speeds, for a given power level. This is accomplished because the two smaller turbines are required to carry the torque that would normally be provided by a single, larger diameter turbine. The larger the diameter of a rotating machine, the larger the stresses are, for a given rotational speed. Creating the smaller diameter turbines allows the engine to operate at a higher rotational speed, for a given stress level.

Embodiments disclosed herein utilize a reheat cycle where heat is transferred from exhaust proximate to an inlet of the first stage turbine to exhaust proximate the inlet of a second stage turbine. Advantageously, this reduces the temperature of exhaust entering the first stage turbine, thus increasing the operating life of the first stage turbine. Also, advantageously, this increases the temperature of exhaust entering the second stage turbine, thus increasing the efficiency of the second stage turbine.

Embodiments disclosed herein also utilize a catalytic converter to heat the combustor exhaust prior to entry into the second stage turbine. Advantageously, by adding additional heat to the exhaust using the catalytic converter, less fuel will be required in the combustor to provide the necessary heat energy to support the micro-turbine engine's output power requirements. This reduction in fuel input, for a given output power level, will increase the micro-turbine engine's thermodynamic efficiency. Also, advantageously, the catalytic converter helps reduces noxious exhaust emissions existing from an outlet of the micro-turbine engine.

Referring to <FIG>, an isometric view of an unmanned aerial vehicle (UAV) <NUM> is illustrated in accordance with an embodiment of the present disclosure. The UAV <NUM> includes a propulsion/lift system <NUM>, for example a plurality of lift rotors <NUM>, operably connected to an electrical power generation system <NUM>, which includes a micro-turbine alternator system <NUM>. In an embodiment, the micro-turbine alternator system <NUM> is a high efficiency Brayton cycle micro-turbine alternator. The UAV <NUM> includes a propulsion system having electric motors <NUM> and lift rotors <NUM> associated with each electric motor <NUM>. Each lift rotor <NUM> is operably connected to the electric motor <NUM> that is configured to rotate the lift rotor <NUM> using electrical power generated by the micro-turbine alternator system <NUM> of the electrical power generation system <NUM>. The micro-turbine alternator system <NUM> is configured to convert fuel to electrical power to power at least the electric motors <NUM> of the lift rotors <NUM>. The fuel is provided from one or more fuel storage tanks <NUM> operably connected to the micro-turbine alternator system <NUM>. In some embodiments, the fuel utilized is JP-<NUM>. The micro-turbine alternator system <NUM> may utilize compressed air provided from a compressed air tank <NUM> at <NUM> psig (<NUM>,<NUM> bar) and regulated to about <NUM> psig (<NUM>,<NUM> bar). The compressed air from the compressed air tank <NUM> of <FIG> may be utilized to provide the motive pressure required to drive the liquid fuel through a turbine speed control valve (not shown) and into a combustion chamber. Alternatively, an electric driven pump may be used in place of the compressed air.

Referring now to <FIG>, with continued reference to <FIG>, an isometric view of an electrically-powered suit <NUM> is illustrated in accordance with an embodiment of the present disclosure. While in <FIG>, the micro-turbine alternator system <NUM> is described as utilized in a UAV <NUM>, the micro-turbine alternator system <NUM> disclosed herein may be readily applied to other systems, and may be utilized in, for example, an electrically-powered suit <NUM>, as shown in <FIG>.

The electrically-powered suit <NUM> is operably connected to an electrical power generation system <NUM>, which includes a micro-turbine alternator system <NUM>. The micro-turbine alternator system <NUM> is configured to convert fuel to electrical power to power the electrically-powered suit <NUM>. The fuel is provided from one or more fuel storage tanks <NUM> operably connected to the micro-turbine alternator system <NUM>. In some embodiments, the fuel utilized is JP-<NUM>. The fuel storage tanks <NUM> may be located on legs of the electrically-powered suit <NUM>, as illustrated in <FIG>.

It is understood that the micro-turbine alternator system <NUM> is not limited to a UAV <NUM> and an electrically-powered suit <NUM> application, and the micro-turbine alternator system <NUM> may be applied to other systems not disclosed herein.

Referring now to <FIG>, an isometric cut-away view of the micro-turbine alternator system <NUM> is illustrated, in accordance with an embodiment of the present disclosure. The micro-turbine alternator system <NUM> includes a first stage compressor <NUM>, a second stage compressor <NUM>, a third stage compressor <NUM>, a first stage turbine <NUM>, and a second stage turbine <NUM>. The first stage compressor <NUM>, the second stage compressor <NUM>, the third stage compressor <NUM>, the first stage turbine <NUM>, and the second stage turbine <NUM> are oriented along a central longitudinal axis A of the micro-turbine alternator system <NUM>. The micro-turbine alternator system <NUM> also includes an electric generator <NUM> located between the first stage compressor <NUM> and the second stage compressor <NUM> as measured along the central longitudinal axis A.

Advantageously, by locating the electric generator <NUM> between the first stage compressor <NUM> and the second stage compressor <NUM>, the overall physical size of the micro-turbine alternator system <NUM> is reduced. As a result, the micro-turbine alternator system <NUM> according to one or more embodiments may be used in a UAV <NUM>, an electrically-powered suit <NUM>, or another system that benefits from untethered, lightweight power generation.

The micro-turbine alternator system <NUM> also includes an alternator stator cooling heat exchanger <NUM> configured to utilize airflow from the first stage compressor <NUM> to cool the electric generator <NUM>. The alternator stator cooling heat exchanger <NUM> may encircle or enclose the electric generator <NUM> and may be configured to pass airflow from the first stage compressor <NUM> through or around the electric generator <NUM>. Advantageously, by locating the electric generator <NUM> between the first stage compressor <NUM> and the second stage compressor <NUM>, moderately cool air in the core flow path C from the first stage compressor <NUM> is forced through the alternator stator cooling heat exchanger <NUM> and heat may be drawn out of the electric generator <NUM> and to the airflow within the alternator stator cooling heat exchanger <NUM>.

The electric generator <NUM> may be a permanent magnet alternator, an induction generator, a switched reluctance generator, a wound field generator, a hybrid generator, or any other type of alternator known to one of skill in the art. As illustrated in <FIG>, the electric generator <NUM> may be a permanent magnet alternator that includes a rotor element <NUM> and a stator element <NUM> radially outward from the rotor element. In other words, the rotor element <NUM> is located radially inward from the stator element <NUM> as measured relative to the central longitudinal axis A. It is understood that the embodiments disclosed herein may be applicable to a rotor element <NUM> that is located radially outward from the stator element <NUM>. The rotor element <NUM> may be rotated around the central longitudinal axis A to generate electricity.

The rotor element <NUM> includes an annular base member <NUM>, an annular array of permanent magnets <NUM> that are respectively coupled to an outer diameter of the annular base member <NUM>. The rotor element <NUM> may include a magnet retention band that fits over an outer diameter of the permanent magnet <NUM>, and keeps the permanent magnet <NUM> on the rotating annular base member <NUM>. In accordance with further embodiments, the stator element <NUM> includes a hub <NUM>, a plurality of spokes <NUM> extending radially inward from the hub <NUM> and conductive elements <NUM> that are wound around the spokes <NUM> to form windings. When the rotor element <NUM> is rotated around the central longitudinal axis A a rotating flux field is generated by the permanent magnets <NUM> and this rotating flux field generates an alternating current in the conductive elements <NUM> to generate electricity for use by the UAV <NUM> of <FIG> or the electrically-powered suit <NUM> of <FIG>.

The micro-turbine alternator system <NUM> includes a combustor <NUM>, in which a fuel-air mixture is combusted, with the combustion products utilized to drive an electric generator <NUM>. In some embodiments, the fuel utilized in the combustor <NUM> is JP-<NUM>. The micro-turbine alternator system <NUM> converts the energy of the combustion products into electrical power by urging the combustion products through the first stage turbine <NUM> and the second stage turbine <NUM>, which are operably connected to and configured to rotate the rotor element <NUM> of the electric generator <NUM>. The electrical energy generated by the electric generator <NUM> may then be rectified via a generator rectifier (not shown) and utilized by the propulsion/lift system <NUM> of <FIG> or the electrically-powered suit <NUM> of <FIG>. The compressed air from the compressed air tank <NUM> of <FIG> may be utilized to provide the motive pressure required to drive the liquid fuel through a turbine speed control valve (not shown) and into the combustor <NUM>.

The first stage compressor <NUM> is located forward of the second stage compressor <NUM> and the third stage compressor <NUM> as measured along the central longitudinal axis A, and the second stage compressor <NUM> is located forward of the third stage compressor <NUM> as measured along the central longitudinal axis A. In other words, the second stage compressor <NUM> is located aft of the first stage compressor <NUM> and the third stage compressor <NUM> is located aft of the second stage compressor <NUM> as measured along the central longitudinal axis A. The forward direction D1 and the aft direction D2 are illustrated in <FIG>. The first stage turbine <NUM> is located forward of the second stage turbine <NUM> as measured along the central longitudinal axis A. In other words, the second stage turbine <NUM> is located aft of the first stage turbine <NUM> as measured along the central longitudinal axis A. The first stage compressor <NUM>, the second stage compressor <NUM>, and the third stage compressor <NUM> are located forward of first stage turbine <NUM> and the second stage turbine <NUM> as measured along the central longitudinal axis A.

The micro-turbine alternator system <NUM> includes a compressor shaft <NUM> oriented along and co-axial to the central longitudinal axis A. In an embodiment, the compressor shaft <NUM> is a tie bolt and is used to compress a rotating group of components including the first stage compressor <NUM>, compressor transfer tube <NUM>, the compressor shaft <NUM>, and a second journal bearing <NUM> in the axial direction, causing the multi-segment shaft to act as a single stiff shaft. The compressor shaft <NUM> may be attached or operably connected to the first stage compressor <NUM>. The micro-turbine alternator system <NUM> includes a turbine shaft <NUM> oriented along and co-axial to the central longitudinal axis A. The turbine shaft <NUM> may be attached or operably connected to the first stage turbine <NUM> and the second stage turbine <NUM>.

The micro-turbine alternator system <NUM> includes a coupling assembly <NUM> configured to operably connect the turbine shaft <NUM> to the compressor shaft <NUM>. The coupling assembly <NUM> may be attached or operably connected to the second stage compressor <NUM>. The compressor shaft <NUM> extends in the aft direction D2 away from the first stage compressor <NUM> and through the electric generator <NUM> to operably connect to the coupling assembly <NUM>. In an embodiment, the compressor shaft <NUM> is located radially inward of the rotor element <NUM>.

Advantageously, locating the electric generator <NUM> between the first stage compressor <NUM> and the second stage compressor <NUM> allows the first stage compressor <NUM> to have a reduced inlet hub diameter that is smaller than a diameter of the rotor element <NUM>. Having a reduced inlet hub diameter DIA1 reduces the inlet flow relative velocity, increasing the aerodynamic performance of the first stage compressor <NUM> and increasing the swallowing capacity of the first stage compressor <NUM>. If the electric generator <NUM> was located forward of the first stage compressor <NUM>, then the compressor shaft <NUM> would have to extend forward of the first stage compressor <NUM> and thus the inlet hub diameter DIA1 would have to be increased to a diameter of the compressor shaft <NUM>, thus decreasing the aerodynamic performance of the first stage compressor <NUM> and decreasing the swallowing capacity of the first stage compressor <NUM>.

The turbine shaft <NUM> extends in the forward direction D1 away from the first stage turbine <NUM> to operably connect to the coupling assembly <NUM>. The turbine shaft <NUM>, the coupling assembly <NUM>, and the compressor shaft <NUM> are configured to rotate in unison. Thus, when combustor exhaust <NUM> from the combustor <NUM> drives rotation of the first stage turbine <NUM> and when catalytic exhaust <NUM> drives rotation from the second stage turbine <NUM>, the rotation of the first stage turbine <NUM> and the second stage turbine <NUM> drives rotation of the turbine shaft <NUM>, which drives rotation of the coupling assembly <NUM> and the compressor shaft <NUM>. The rotation of the compressor shaft <NUM> drives rotation of the first stage compressor <NUM>. The rotation of the coupling assembly <NUM> drives rotation of the second stage compressor <NUM>. The third stage compressor <NUM> is operably connected to the second stage compressor <NUM> and the turbine shaft <NUM>, and thus rotation of the second stage compressor <NUM> and the turbine shaft <NUM> drives rotation of the third stage compressor <NUM>.

It is understood that while the compressor shaft <NUM>, the turbine shaft <NUM>, and the coupling assembly <NUM> are described as three different shafts, the embodiments disclosed herein may be applicable to micro-turbine alternator system <NUM> having one or more shafts. In an embodiment, the electric generator <NUM> is disposed along the one or more shafts between the first stage compressor <NUM> and the second stage compressor <NUM>. In another embodiment, the electric generator <NUM> is disposed along the compressor shaft <NUM> between the first stage compressor <NUM> and the second stage compressor <NUM>. The electric generator <NUM> is located aft of the first stage compressor <NUM> and forward of the second stage compressor <NUM>. In another embodiment, at least one of the one or more drive shafts passes through the electric generator <NUM>. In another embodiment, the compressor shaft <NUM> passes through the electric generator <NUM>.

The compressor shaft <NUM>, the turbine shaft <NUM>, and the coupling assembly <NUM> are coaxial and rotate via the bearing systems about the central longitudinal axis A, which is colinear with their longitudinal axes. The bearing system includes a first journal bearing <NUM> located between the compressor transfer tube <NUM> and the frame <NUM> of the micro-turbine alternator system <NUM>. The bearing system includes a second journal bearing <NUM> located between the coupling assembly <NUM> and the frame <NUM> of the micro-turbine alternator system <NUM>. The bearing system includes a third journal bearing <NUM> located between the turbine shaft <NUM> and the frame <NUM> of the micro-turbine alternator system <NUM>.

Advantageously, locating the electric generator <NUM> between the first stage compressor <NUM> and the second stage compressor <NUM> provides for very effective bearing placement around the compressor shaft <NUM>, which increases the stiffness of the compressor shaft <NUM>. The increased stiffness of the compressor shaft <NUM> allows for an increase in the critical speed of the compressor shaft <NUM>.

Also, advantageously, by locating the electric generator <NUM> between the first stage compressor <NUM> and the second stage compressor <NUM>, the alternator stator cooling heat exchanger <NUM> helps reduce the operating temperature of the electric generator <NUM>, while the airflow through the alternator stator cooling heat exchanger <NUM> also experiences a pressure drop. This pressure drop through the alternator stator cooling heat exchanger <NUM> forces some of the airflow from the first stage compressor <NUM> through the rotor element <NUM> and to a stator gap between the rotor element <NUM> and the stator element <NUM>, which provides cooling air to the rotor element <NUM>, the first journal bearing <NUM>, and the second journal bearing <NUM>.

The compressor transfer tube <NUM> extends from the first stage compressor <NUM> to the second stage compressor <NUM> through the electric generator <NUM>. The compressor transfer tube <NUM> is co-axial with the electric generator <NUM>. The rotor element <NUM> with the annular base member <NUM> and the annular array of permanent magnets <NUM> are located radially inward of the compressor transfer tube <NUM> measured relative to the central longitudinal axis A. The stator element <NUM> with the hub <NUM>, the conductive elements <NUM>, and the spokes <NUM> are located radially outward of the compressor transfer tube <NUM> measured relative to the central longitudinal axis A.

The first stage compressor <NUM>, the second stage compressor <NUM>, and the third stage compressor <NUM> drive air along a core flow path C for compression and communication in the combustor <NUM>. The airflow in the core flow path C is compressed by the first stage compressor <NUM>, the second stage compressor <NUM>, and the third stage compressor <NUM>, is mixed with fuel and burned in the combustor <NUM>, and is then expanded over the first stage turbine <NUM> and the second stage turbine <NUM>. The first stage turbine <NUM> and the second stage turbine <NUM> rotationally drive the turbine shaft <NUM> in response to the expansion. The combustion products are exhausted from the second stage turbine <NUM> through a turbine exit <NUM>.

Each of the first stage compressor <NUM>, the second stage compressor <NUM>, the third stage compressor <NUM>, the first stage turbine <NUM>, and the second stage turbine <NUM> may include rows of rotor assemblies (shown schematically) that carry airfoils that extend into the core flow path C. For example, the rotor assemblies can carry a plurality of rotating blades <NUM>. The blades <NUM> of the rotor assemblies create or extract energy (in the form of pressure) from the core airflow that is communicated through the micro-turbine alternator system <NUM> along the core flow path C.

The micro-turbine alternator system <NUM> may include an auxiliary turbo charger <NUM> to pre-compress the airflow <NUM> prior to entering the core flow path C. The auxiliary turbo charger <NUM> includes a turbo compressor <NUM> and a turbine <NUM> operably connected to the turbo compressor <NUM> through a turbo compressor drive shaft <NUM>. The turbo compressor <NUM> is configured to rotate when the turbine <NUM> rotates.

The turbo compressor <NUM> is configured to pull external airflow <NUM> through one or more air inlets <NUM> in the frame <NUM> into a compressor flow path C1. The turbo compressor <NUM> is configured to compress the external airflow <NUM> in the compressor flow path C1 and deliver the airflow <NUM> to the first stage compressor <NUM> in the core airflow path C.

Each of the turbine <NUM> and the turbo compressor <NUM> may include rows of rotor assemblies (shown schematically) that carry airfoils that extend into the compressor flow path C1. For example, the rotor assemblies can carry a plurality of rotating blades <NUM>. The blades <NUM> of the rotor assemblies for the turbine <NUM> extract energy (in the form of pressure and temperature) from catalytic exhaust <NUM> (discussed further herein) that is communicated through the micro-turbine alternator system <NUM> along the core flow path C. The blades <NUM> of the rotor assemblies for the turbo compressor <NUM> create energy (in the form of pressure and temperature) from the airflow <NUM> that is communicated through the micro-turbine alternator system <NUM> along the compressor flow path C1.

The catalytic exhaust <NUM> exiting the turbine exit <NUM> is directed to the turbine <NUM> of the auxiliary turbo charger <NUM>. The catalytic exhaust <NUM> is then expanded over the turbine <NUM> of the auxiliary turbo charger <NUM>. The turbine <NUM> rotationally drives the turbo compressor drive shaft <NUM> in response to the expansion. Rotation of the turbo compressor drive shaft <NUM> causes the turbo compressor <NUM> to rotate and compress the airflow <NUM> within the compressor flow path C1.

Some embodiments further include a thermal electric energy recovery system <NUM>, configured to recover additional energy from the catalytic exhaust <NUM> of the micro-turbine alternator system <NUM> before the catalytic exhaust <NUM> has flowed through the turbine <NUM> of the auxiliary turbo charger <NUM>.

Referring now to <FIG>, with continued reference to <FIG>, an enlarged isometric cut-away view of an exhaust turbine reheat cycle <NUM> and a catalytic converter <NUM> of the micro-turbine alternator system <NUM> of <FIG> is illustrated, in accordance with an embodiment of the present disclosure. The exhaust turbine reheat cycle <NUM> is the path taken by the combustor exhaust <NUM> exiting the combustor <NUM> through the first stage turbine <NUM> to the catalytic converter <NUM>.

The exhaust turbine reheat cycle <NUM> includes a heat exchanger <NUM> configured to transfer heat H1 from combustor exhaust <NUM> entering the first stage turbine <NUM> to combustor exhaust <NUM> entering the catalytic converter <NUM>, which advantageously helps increase the efficiency of the second stage turbine <NUM> following the catalytic converter <NUM>, while reducing the temperature of the combustor exhaust <NUM> entering the first stage turbine <NUM>. The reduction in the temperature of the combustor exhaust <NUM> entering the first stage turbine <NUM> helps extended the life of the first stage turbine <NUM> by reducing an operating temperature of the first stage turbine <NUM>. The second stage turbine <NUM> is located downstream of the first stage turbine <NUM> in a direction of a flow of the combustor exhaust <NUM> and the catalytic exhaust <NUM>.

The exhaust turbine reheat cycle <NUM> also includes a catalytic converter <NUM>. The catalytic converter <NUM> is configured to convert the combustor exhaust <NUM> to a catalytic exhaust <NUM>, which includes at least exothermic heat H2. In a perfect chemical rection between fuel and air in the combustor <NUM>, the combustor exhaust <NUM> would only include carbon dioxide (CO<NUM>) and water (H<NUM><NUM>). However, in real-world combustion, the combustor exhaust <NUM> may include carbon dioxide (CO<NUM>), water (H<NUM><NUM>) and imperfect combustion byproducts including, but not limited to, nitrous oxide (NOx), carbon monoxide (CO), unburned fuel/hydrocarbons (HC), oxygen (O2), and/or nitrogen (N<NUM>). The catalytic converter <NUM> is configured to convert the combustor exhaust <NUM> with the imperfect combustion byproducts into the catalytic exhaust <NUM> through a reduction process and an oxidation process. The reduction process is configured to convert the nitrous oxide (NOx) and the carbon monoxide (CO) into nitrogen (N<NUM>) and carbon dioxide (CO<NUM>). The oxidation process is configured to convert the unburned fuel/hydrocarbons (HC), the carbon monoxide (CO), and the oxygen (O<NUM>) into water (H<NUM>O) and carbon dioxide (CO<NUM>). The reaction within the catalytic converter <NUM> is highly exothermic and produces exothermic heat H<NUM>. The catalytic exhaust <NUM> includes at least the exothermic heat H<NUM> and nitrogen (N<NUM>), water (H<NUM><NUM>), and/or carbon dioxide (CO<NUM>).

Advantageously, the reaction within the catalytic converter <NUM> helps reduce pollutant emissions from the micro-turbine alternator system <NUM>. Advantageously, this exothermic heat H2 further increases the temperature of the catalytic exhaust <NUM> entering the second stage turbine <NUM> and thus further increase the efficiency of the second stage turbine <NUM>.

The catalytic converter <NUM> includes one or more catalysts to catalyze the reaction with the combustor exhaust <NUM> within the catalytic converter <NUM>. The catalyst may include platinum, or any other catalyst known to one of skill in the art. In an embodiment, the catalytic converter <NUM> is a three-way catalytic converter.

The catalytic converter <NUM> is located between the first stage turbine <NUM> and the second stage turbine <NUM> with regard to flow. In other words, the catalytic converter <NUM> is located downstream of the first stage turbine <NUM> and upstream of the second stage turbine <NUM> in a direction a flow of the combustor exhaust <NUM> and the catalytic exhaust <NUM>. In an alternative embodiment, the catalytic converter <NUM> may be before or upstream of the heat exchanger <NUM>.

Combustor exhaust <NUM> exits the combustor <NUM> via a first passageway <NUM>. The first passageway <NUM> extends from the combustor <NUM> to the heat exchanger <NUM> and fluidly connects the combustor <NUM> to the heat exchanger <NUM>. The heat exchanger <NUM> may be an air-to-air heat exchanger. The heat exchanger <NUM> includes one or more heat rejection passageways <NUM> and one or more heat absorption passageways <NUM>. The one or more heat absorption passageways <NUM> are thermally connected to the one or more heat rejection passageways <NUM>. The one or more heat absorption passageways <NUM> may be physically connected to the one or more heat rejection passageways <NUM>. The heat exchanger <NUM> is configured to transfer heat H1 from the combustor exhaust <NUM> in the one or more heat rejection passageways <NUM> to the combustor exhaust <NUM> in the one or more heat absorption passageways <NUM>.

Specifically, the first passageway <NUM> extends from the combustor <NUM> to the one or more heat rejection passageways <NUM> and fluidly connects the combustor <NUM> to the one or more heat rejection passageways <NUM>. The combustor exhaust <NUM> flows from the combustor <NUM> through the first passageway <NUM> and into the one or more heat rejection passageways <NUM>.

The one or more heat rejection passageways <NUM> extend from the first passageway <NUM> to a second passageway <NUM> and fluidly connect the first passageway <NUM> to the second passageway <NUM>. The combustor exhaust <NUM> flows from the first passageway <NUM> through the one or more heat rejection passageways <NUM> and into second passageway <NUM>.

The second passageway <NUM> extends from the one or more heat rejection passageways <NUM> to the first stage turbine <NUM> and fluidly connects the one or more heat rejection passageways <NUM> to the first stage turbine <NUM>. The combustor exhaust <NUM> flows from the one or more heat rejection passageways <NUM> through the second passageway <NUM> and into the first stage turbine <NUM>.

The first stage turbine <NUM> extends from the second passageway <NUM> to a third passageway <NUM> and fluidly connects the second passageway <NUM> to the third passageway <NUM>. The combustor exhaust <NUM> flows from the second passageway through the first stage turbine <NUM> and into the third passageway <NUM>.

The third passageway <NUM> extends from the first stage turbine <NUM> to the one or more heat absorption passageways <NUM> and fluidly connects the first stage turbine <NUM> to the one or more heat absorption passageways <NUM>. The combustor exhaust <NUM> flows from the first stage turbine <NUM> through the third passageway <NUM> and into the one or more heat absorption passageways <NUM>.

The one or more heat absorption passageways <NUM> extend from the third passageway <NUM> to a fourth passageway <NUM> and fluidly connects the third passageway <NUM> to the fourth passageway <NUM>. The combustor exhaust <NUM> flows from the third passageway <NUM> through the one or more heat absorption passageways <NUM> and into the fourth passageway <NUM>. Heat H1 is transferred to the combustor exhaust <NUM> in the one or more heat absorption passageways <NUM> from the one or more heat rejection passageways <NUM>.

The fourth passageway <NUM> extends from the one or more heat absorption passageways <NUM> to the catalytic converter <NUM> and fluidly connects the one or more heat absorption passageways <NUM> to the catalytic converter <NUM>. The combustor exhaust <NUM> flows from the one or more heat absorption passageways <NUM> through the fourth passageway <NUM> and into the catalytic converter <NUM>.

The catalytic converter <NUM> extends from the fourth passageway <NUM> to a fifth passageway <NUM> and fluidly connects the fourth passageway <NUM> to the fifth passageway <NUM>. The combustor exhaust <NUM> flows from the fourth passageway <NUM> through the catalytic converter <NUM>, where it is converted into the catalytic exhaust <NUM>, which then flows into the fifth passageway <NUM>.

The fifth passageway <NUM> extends from the catalytic converter <NUM> to the second stage turbine <NUM> and fluidly connects the catalytic converter <NUM> to the second stage turbine <NUM>. The catalytic exhaust <NUM> flows from the catalytic converter <NUM> through the fifth passageway <NUM> and into the second stage turbine <NUM>.

The second stage turbine <NUM> extends from the fifth passageway <NUM> to a sixth passageway <NUM> and fluidly connects the fifth passageway <NUM> to the sixth passageway <NUM>. The catalytic exhaust <NUM> flows from the fifth passageway <NUM> through the second stage turbine <NUM> and into the sixth passageway <NUM>.

The sixth passageway <NUM> extends from the second stage turbine <NUM> to the turbine <NUM> of the auxiliary turbo charger <NUM> (see <FIG>) and fluidly connects the second stage turbine <NUM> to the turbine <NUM>. The catalytic exhaust <NUM> flows from the second stage turbine <NUM> through the sixth passageway <NUM> and into the turbine <NUM> of the auxiliary turbo charger <NUM>.

In one non-limiting example, a temperature of the combustor exhaust <NUM> may be at a first temperature in the first passageway <NUM>, a second temperature in the second passageway <NUM>, a third temperature in the third passageway <NUM>, and a fourth temperature in the fourth passageway <NUM>. The catalytic exhaust <NUM> may be at a fifth temperature in the fifth passageway <NUM> and a sixth temperature in the sixth passageway <NUM>. The second temperature may be less than the first temperature, the third temperature may be less than the second temperature, the fourth temperature may be less than the fifth temperature and the second temperature, the fifth temperature may be equivalent to the second temperature, the fifth temperature may be greater than the fourth temperature, the sixth temperature may be less than the third temperature.

Technical effects and benefits of the features described herein include flowing exhaust through a catalytic converter to heat the exhaust prior to flowing said exhaust into a second stage turbine to increase the efficiency of the second stage turbine.

While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made without departing from the scope of the present disclosure.

Claim 1:
An electrical power generation system, comprising:
a micro-turbine alternator, comprising:
a combustor (<NUM>);
a first stage turbine (<NUM>) configured to be driven by a combustor exhaust from the combustor;
at least one compressor operably connected to the combustor to provide a compressed airflow to the combustor;
a catalytic converter (<NUM>) configured convert the combustor exhaust to a catalytic exhaust that comprises at least exothermic heat;
a second stage turbine (<NUM>) configured to be driven by the catalytic exhaust from the catalytic converter;
one or more shafts connecting the first stage turbine (<NUM>) and the second stage turbine (<NUM>) to the at least one compressor such that rotation of the first stage turbine and the second stage turbine drives rotation of the at least one compressor; and characterized by
an exhaust turbine reheat cycle (<NUM>) configured to transfer heat from the combustor exhaust entering the first stage turbine to the combustor exhaust entering the catalytic converter.