Air supply apparatus, ship including the same, and method of supplying air to an air-powered device

Abstract

An air supply apparatus (100) is described. The air supply apparatus includes a turbomachine (110) having a compressor (111) and a turbine (112). The compressor includes a variable compressor geometry (11V). The compressor (111) is connected with an engine (130) via an air supply system (120): The turbine (112) is connected with the engine (130) via an exhaust gas piping (140). Additionally, the air supply apparatus includes at least one electric machine (150) coupled to at least one of the compressor (111) and the turbine (112). Further, the air supply apparatus includes an air-powered device (160) connected with the air supply system (120). The air powered device can be an air lubrication device for resistance reduction of a ship.

Description

AIR SUPPLY APPARATUS, SHIP INCLUDING THE SAME, AND METHOD OF SUPPLYING AIR TO AN AIR-POWERED DEVICETECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to air supply apparatuses for air-powered devices. Further, embodiments of the present disclosure relate to methods of supplying air to an air-powered device.BACKGROUND

[0002] Generally, a ship receives friction resistance of water during marine navigation on its submerged surface of the ship’s bottom. Especially for large ships, e.g. cargo ships, a large portion of the ship’s hull resistance of results from friction resistance generated by relative flow of outside water at the ship’s bottom.

[0003] To reduce ship’s hull friction resistance air lubrication can be used, particularly by discharging air into surroundings of the ship’s hull. The reduction of friction resistance has a large fuel economy improving effect, and thus represent effective means to reduce the CO2emission of the ship.

[0004] In the state of the art, there are various systems and approaches for the production of air bubbles for the hull lubrication. For instance, for the generation of air bubbles for hull lubrication, the prior art teaches direct usage of separate compressors or blowers. However, the known systems for providing air to air-powered devices, such as hull lubrication devices, have some disadvantages, for example in terms of energy consumption and efficiency.

[0005] Accordingly, in view of the above, there is a demand for improved air supply apparatuses for air-powered devices, such as air-lubrication devices, as wells as for improved methods of supplying air to an air-powered device which at least partially overcome some of the problems of the state of the art.SUMMARY

[0006] In light of the above, an air supply apparatus and a method of supplying air to an air-powered device according to the independent claims are provided. Further aspects, advantages, and features are apparent from the dependent claims, the description, and the accompanying drawings.

[0007] According to an aspect of the present disclosure, an air supply apparatus is provided. The air supply apparatus includes a turbomachine having a compressor and a turbine. The compressor includes a variable compressor geometry. The compressor is connected with an engine via an air supply system. The turbine is connected with the engine via an exhaust gas piping. Additionally, the air supply apparatus includes at least one electric machine coupled to at least one of the compressor and the turbine. Further, the air supply apparatus includes an air-powered device connected with the air supply system. In particular, the air powered device can be an air lubrication device for a ship.

[0008] Accordingly, the air supply apparatus of the present disclosure is improved compared to conventional apparatuses used for operating an air- powered device, particularly with respect to energy efficiency. In particular, the electric machine beneficially allows for providing the required power for the compressor to supply air to the air-powered device, but typically does not generate the necessary compressor map width, which is typically equivalent to the compressor operating field width. The combination of the electric machine and the variable compressor geometry has the advantage that the required power can be provided to the compressor to supply the requiredairflow to the engine and the air-powered device. Typically, the necessary compressor map width can be characterized in that the width of the compressor map is sufficient to compress the required airflow in at least each of the following three cases: (1) only for the engine over its whole operating range; (2) the engine at partial power and the air-powered device provided with reduced airflow; (3) the engine at full power and the air-powered device provided its maximal airflow.

[0009] According to a further aspect of the present disclosure, a ship including an air supply apparatus according to any embodiments described herein is provided.

[0010] According to another aspect of the present disclosure, a method of supplying air to an air-powered device is provided. The method includes driving a compressor of a turbomachine for charging an engine by using an electric machine. Additionally, the method includes adjusting a compressor aerodynamic characteristic to an airflow passing through the compressor by utilizing a variable compressor geometry. In other words, the variable compressor geometry is used to adjust the compressor’s aerodynamic characteristics, influencing the airflow through the compressor, particularly the air outflow of the compressor, specifically air outflow parameters, such as pressure and air flow rate. Further, the method includes supplying air from the compressor via an air supply system to the air-powered device.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:Fig. 1 shows a schematic view of an air supply apparatus according to embodiments described herein;Figs. 2 to 8 show schematic views of an air supply apparatus according to further embodiments described herein;Fig. 9 shows a flowchart for illustrating a method of supplying air to an air -powered device according to embodiments described herein;Fig. 10 shows a schematic views of an air supply apparatus according to further embodiments of the present disclosure connected to an inflatable sail system.DETAILED DESCRIPTION OF EMBODIMENTS

[0012] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0013] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment can apply to a corresponding part or aspect in another embodiment as well.

[0014] With exemplary reference to Figs. 1 to 8, an air supply apparatus 100 according to embodiments of the present disclosure are described.

[0015] According to embodiments, which can be combined with other embodiments described herein, the air supply apparatus 100 includes a turbomachine 110 having a compressor 111 and a turbine 112. The compressor 111 includes a variable compressor geometry 11 V. The compressor 111 is connected with an engine 130 via an air supply system 120. The turbine 112 is connected with the engine 130 via an exhaust gas piping 140. Additionally, the air supply apparatus 100 includes at least one electric machine 150 coupled to at least one of the compressor 111 and the turbine 112. Fig. 1 shows an example, where the electric machine 150 is arranged between the compressor 111 and the turbine 112. Accordingly, the electric machine 150 may be coupled to the compressor 111 and the turbine 112, e.g. via a shaft 113 connecting the compressor 111 and the turbine 112. Fig. 2 shows another example, where the electric machine 150 is arranged on the compressor side and coupled to the compressor 111. Further, as exemplarily shown in Figs. 1 to 8, the air supply apparatus 100 includes an air-powered device 160 connected with the air supply system 120.

[0016] Accordingly, the air supply apparatus according to embodiments of the present disclosure is improved compared to conventional apparatuses used for operating an air-powered device. In particular, the air supply apparatus according to embodiments described herein has a better energy efficiency as compared to the air supply apparatuses of the state of the art. In particular, as compared to the state of the art, the air supply apparatus according to embodiments described herein does not face the problem of a too narrow compressor map and / or insufficient turbocharger power, particularly due to the possibility of compensating power lack with an electric machine by injecting electrical power to the rotor(s) of the turbomachine (PTI: Power Take-In) and / or exhaust gas energy recovery (PTO: Power Take- Off).

[0017] In the present disclosure, an “air supply apparatus” can be understood as an apparatus configured to supply air, particularly compressedair, to one or more air-powered devices. Accordingly, the air supply apparatus may include one or more air-powered devices. An “air-powered device” can be understood as a device that operates using air, particularly compressed air. For instance, an air-powered device can employ air, particularly compressed air, to carry out its technical function. Typically, the air-powered device uses air, particularly compressed air, as its primary source of power. For example, compressed air, typically generated by a compressor, is directed into the device, where it is used to fulfill a technical function or is converted into mechanical motion, enabling the device to perform various tasks and functions. In other words, the term “air-powered device” encompasses a wide range of devices and equipment that utilize air, particularly compressed air, to perform various functions or tasks. Air-powered devices can include pneumatic tools, pneumatic control systems, air compressors, and other equipment that rely on the energy stored in pressurized air to generate motion, apply force, or carry out specific operations.

[0018] In the present disclosure, a “variable compressor geometry” can be understood as a device or measure configured to adjust the compressor aerodynamic characteristic to the airflow passing through the compressor. For instance, the variable compressor geometry may be provided by adjustable inlet guide vanes and / or adjustable diffuser vanes. The variable compressor geometry offers the advantage of enabling flexible and optimized operation across a wide range of conditions and air flow.

[0019] According to a particular example, the air-powered device can be an air lubrication device for resistance reduction of a ship. An “air lubrication device” for resistance reduction of a ship can be understood as a device configured to reduce the frictional resistance between the ship's hull and the surrounding water. Typically, the air lubrication device is configured for injecting a layer of tiny air bubbles under the ship's hull to create a thin air cushion or lubrication layer, which reduces the friction between the hull and water and the ship experiences less drag as it moves through the water. Thisresults in improved fuel efficiency, lower energy consumption, and a smaller environmental footprint.

[0020] According to an embodiment, which can be combined with other embodiments described herein, the air-powered device 160 includes an inflatable sail system 190, as exemplarily shown in Fig. 10. Although not explicitly shown, it is to be understood that the inflatable sail system 190 may be provided in addition to any other air-powered device described herein, for instance in combination with an air lubrication device for resistance reduction of a ship.

[0021] In the present disclosure, an “inflatable sail system” can be understood as a system having one or more inflatable sails configured to harness wind power for propulsion. Unlike conventional rigid sails, inflatable sails are typically made from flexible, lightweight materials that can be inflated to take shape and capture wind, providing thrust to propel the ship. The provision of an inflatable sail system can be beneficial to reduce fuel consumption and emissions by using wind as a supplementary or primary energy source.

[0022] Inflatable sails are typically constructed from durable, flexible fabrics (such as high-strength composites or polymers) that can be filled with air to form a rigid, aerodynamic shape. When not in use, the sails can be deflated and stowed away compactly, offering space-saving advantages over traditional sails. Once inflated, the sail functions similarly to an airfoil (like an airplane wing), with the wind generating lift that propels the ship forward. Some systems might include multiple chambers or sections that can be individually inflated to optimize the sail's shape depending on wind conditions. The inflatable sail system can be automated, allowing adjustment of the sail position, shape, and angle, particularly by using control systems. Providing an automated inflatable sail system beneficially ensures that the sail captures the wind as efficiently as possible, for instance through computeralgorithms or sensors that track wind direction and speed. Typically, the inflatable sail system is used in conjunction with another other propulsion system, such as engines. Accordingly, the inflatable sail system can be part of a hybrid power model, where the ship can switch between or combine wind and engine power to reduce fuel consumption and CO2emissions.

[0023] With exemplary reference to Fig. 10, according to embodiments, which can be combined with other embodiments described herein, the air supply system 120 includes a pressure control device 191, particularly when the air supply system 120 is connected to an inflatable sail system 190. For instance, the pressure control device 191 can include a valve and / or flow expander. The provision of a pressure control device 191 may be beneficial to protect the inflatable sail system 190 from overpressure.

[0024] According to embodiments, which can be combined with other embodiments described herein, the at least one electric machine 150 is an electric motor-generator configured to convert electrical energy into mechanical energy and vice versa. In other words, the at least one electric machine 150 can be configured as a motor to convert electrical energy into mechanical energy. Additionally, or alternatively, the at least one electric machine 150 can be configured as a generator to convert mechanical energy into electrical energy. In the case of two or more electric machines, at least two of the electric machines may be configured differently (e.g., at least one motor and at least one generator) or in the same way (e.g. at least two motors or at least two generators).

[0025] A turbomachine including an electric machine as described herein may also be referred to as eTurbo or electrically assisted turbomachine. Employing an eTurbo according to embodiments of the present disclosure, provides the possibility to obtain at least one of the functionalities of Power Take-Off (PTO) or Power Take-In (PTI). PTI refers to the ability of the electric machine to act as a motor. When the electric machine functions as amotor, it draws electrical power to drive the turbomachine. For example, the electric machine functions as a motor and is coupled to a compressor, a power boost to the engine's intake can be provided, which can enhance performance and responsiveness. This is particularly useful during acceleration or when additional power is needed. PTO refers to the ability of the electric machine to act as a generator. When the electric machine functions as a generator, it harnesses excess mechanical energy from the turbomachine and converts it into electrical power. The generated electrical power can be used for various purposes, such as charging a battery or powering other electrical systems, and / or can be added to the produced electric power if the engine is coupled to an electric generator.

[0026] With exemplary reference to Fig. 1, according to embodiments, which can be combined with other embodiments described herein, the compressor 111 and the turbine 112 are connected via a shaft 113. Further, the at least one electric machine 150 can be arranged between the compressor 111 and the turbine 112. Alternatively, as exemplarily shown in Fig. 2, the at least one electric machine 150 can be arranged on the compressor side and coupled to the compressor 111.

[0027] According to embodiments, the turbomachine 110 can be a turbocharger. The turbocharger can be a shafted turbocharger, as exemplarily shown in Fig. 1. A “shafted turbocharger” can be understood as a turbocharger, where the compressor and the turbine are mechanically connected via a shaft. Alternatively, the turbocharger can be a non-shafted turbocharger, as exemplarily shown in Fig. 3. A “non-shafted turbocharger” can be understood as a turbocharger, where the compressor and the turbine are not mechanically connected or mechanically coupled. In other words, in a non-shafted turbocharger, the compressor and the turbine are typically configured to operate independently and are not connected by a central shaft. Instead, the compressor and the turbine can be arranged in close proximity,e.g., within the same housing or assembly, but do not share a common shaft connecting them.

[0028] According to embodiments, which can be combined with other embodiments described herein, the at least one electric machine 150 includes a first electric machine 151 coupled to the compressor 111 and a second electric machine 152 coupled to the turbine 112, as exemplarily shown in Fig. 3. In particular, the first electric machine 151 coupled to the compressor 111 can be a motor or a generator. Similarly, the second electric machine 152 coupled to the turbine 112 can be a motor or a generator. According to an example, the first electric machine 151 coupled to the compressor 111 is a motor and the electric machine 152 coupled to the turbine 112 is a generator.

[0029] With exemplarily reference to Fig. 3, according to embodiments, which can be combined with other embodiments described herein, the first electric machine 151 and the second electric machine 152 are connected with a controller 153. Typically, the controller 153 is configured for controlling the first electric machine 151 and the second electric machine 152. Accordingly, an electrical compressor and an electrical turbine may be provided which are only linked electrically via the controller 153, i.e. without any mechanical connection.

[0030] In particular, it is to be understood that the controller 153 is configured to perform several possible functions or tasks related to managing the first electric machine 151 and / or the second electric machine 152. Exemplary possible controlling functions of the controller explained in the following.

[0031] Startup and Shutdown Control: The controller may be configured for starting up and shutting down the electric machine(s) as needed. This function may include ensuring that the first electric machine 151 and / or thesecond electric machine 152 operate within safe parameters during these transitions.

[0032] Speed and Power Control: The controller may be configured to regulate the speed and power output of the electric machine(s). This could involve adjusting the voltage, current, and frequency supplied to the electric machine(s) to achieve specific performance objectives.

[0033] Load Balancing: The controller may be configured to distribute loads between the multiple electric machines to ensure they operate efficiently and do not become overloaded. For example, the workload may be shifted from one machine to another as necessary.

[0034] Fault Detection and Response: The controller may be configured to monitor the electric machine(s) for any faults or malfunctions, such as overheating or electrical faults. If an issue is detected, the controller may implement protective measures or trigger alarms.

[0035] Synchronization: In some applications, the multiple electric machines might need to work together or in coordination. The controller can be configured to ensure that operations of multiple electric machines are synchronized to achieve specific tasks.

[0036] Energy Efficiency Optimization: The controller may be configured to optimize the energy consumption of the electric machine(s), by making sure the electric machine(s) operate efficiently and within set energy efficiency standards.

[0037] Safety Control: The controller may be configured for ensuring that the electric machine(s) operate safely within specified limits and conditions.

[0038] In summary, it is to be understood that the controller 153 is configured to manage and regulate the operation of one or more electric machines, e.g. the first electric machine 151 and / or the second electricmachine 152. The functions of the controller 153 can vary depending on the specific application and may involve various control and monitoring tasks to ensure that the electric machine(s) operate efficiently, safely, and in accordance with the intended purpose.

[0039] With exemplary reference to Figs. 1 to 3, according to embodiments, which can be combined with other embodiments described herein, the air supply system 120 includes a first air supply piping 121 for supplying air to an intake manifold 131 of the engine 130. Additionally, the air supply system 120 may include a second air supply piping 122 connecting the air- powered device 160 with the first air supply piping 121. Additionally, or alternatively, the second air supply piping 122 may connect the air-powered device 160 with the intake manifold 131. In other words, the second air supply piping 122 may provide a fluid communication between the air-powered device 160 and the first air supply piping 121 and / or the intake manifold 131.

[0040] According to embodiments, which can be combined with other embodiments described herein, the first air supply piping may include a charge air cooler 170, exemplarily shown in Fig. 3. For instance, the second air supply piping 122 can be connected, particularly be in fluid communication, with the first air supply piping 121 upstream of the charge air cooler 170. Additionally, or alternatively, the second air supply piping 122 can be connected, particularly be in fluid communication, with the first air supply piping 121 downstream of the charge air cooler 170.

[0041] With exemplary reference to Fig. 3, according to embodiments, which can be combined with other embodiments described herein, the air supply system 120 may include one or more elements selected from the group consisting of: a valve 181 to control air mass flow from the compressor 111 to the air-powered device 160, an expander 182 to expand pressurized air and to convert internal energy of the pressurized air into mechanical or electrical energy, and a tank 183 for storing pressurized air. In particular, the supplysystem 120 may include one or more valves 181, as exemplarily shown in Fig. 3. For instance, one or more valves may be provided in the first air supply piping 121 and / or the second air supply piping 122. As exemplarily shown in Fig. 3, a valve 181 can also be provided in a supply line from the tank 183. Further, as exemplarily shown in Fig. 3, the supply system 120 may include one or more expanders 182. For instance, one or more expanders 182 may be provided in the first air supply piping 121 and / or the second air supply piping 122. Moreover, it is to be understood that although only one tank 183 connected, particularly in fluid communication, with the supply system 120, particularly the first supply piping 121, is shown in Fig. 3, two or more tanks may be provided which can be connected to the supply system 120. For instance, one or more tanks 183 can be connected to, particularly be in fluid communication with, the first supply piping 121 and / or one ormore tanks 183 can be connected to, particularly be in fluid communication with, the second supply piping 122.

[0042] With exemplary reference to Figs. 4 to 8, according to embodiments, which can be combined with other embodiments described herein, the air supply apparatus 100 may include a first turbocharger 110A and a second turbocharger HOB. As exemplarily shown in Figs. 4 to 6, the first turbocharger 110A and the second turbocharger HOB can be arranged parallel with respect to each other. More generally, the air supply apparatus 100 may include a parallel multi -turbo configuration with two or more parallel turbochargers.

[0043] Typically, the first turbocharger 110A has a first compressor 111 A and a first turbine 112 A. The first compressor 111 A may have a first variable compressor geometry 11VA. The first turbocharger 110A can be a shafted turbocharger or a non-shafted turbocharger. Similarly, the second turbocharger 110B typically has a second compressor 11 IB and a second turbine 112B. The second compressor 11 IB may have a second variablecompressor geometry 11 VB. The second turbocharger HOB can be a shafted turbocharger or a non-shafted turbocharger.

[0044] With exemplary reference to Fig.4, according to embodiments which can be combined with other embodiments described herein, the first turbocharger 110A may be provided with a first electric machine 151 and the second turbocharger HOB may be provided with a second electric machine 152. In particular, the first electric machine 151 can be arranged between the first compressor 111A and the first turbine 112A. The second electric machine 152 can be arranged between the second compressor 11 IB and the second turbine 112B.

[0045] With exemplary reference to Fig. 5, it is to be understood, that according to embodiments which can be combined with other embodiments described herein, that two or more turbochargers may be provided, wherein at least one turbocharger is a standard turbocharger, i.e. a turbocharger without any elective machine. Fig. 5 shows a multi-turbo configuration, where the first turbocharger 110A is an electric turbocharger having a first electric machine 151 and the second first turbocharger 11 OB is a standard or regular turbocharger without any electric machine.

[0046] With exemplary reference to FIGS. 4 and 5, it is to be understood that the multi-turbo configuration may configured such that the compressors of the multi -turbo configuration supply air to the same intake manifold. More specifically, as exemplarily shown in FIGS. 4 and 5, the air supply system 120 may be configured such that air from the first compressor 111 A and from the second compressor 11 IB can be provided to the intake manifold 131 of the engine 130.

[0047] With exemplary reference to Fig. 6, according to embodiments which can be combined with other embodiments described herein, the air supply apparatus 100 may include two or more engines. Fig. 6 shows an exemplary embodiment with a first engine 130 A and a second engine 130B.Accordingly, a multi-turbo configuration may be provided for providing air to a first intake manifold 131 A of the first engine 130A and a second intake manifold 13 IB of the second engine 130B. More specifically, the air supply apparatus 100 may be configured for providing air from a first compressor 111 A, for example of a first turbocharger 110A according to any embodiments described herein, to the first intake manifold 131 A of the first engine 130A. Additionally, the air supply apparatus 100 may be configured for providing air from a second compressor 11 IB, for example of a second turbocharger HOB according to any embodiments described herein, to the second intake manifold 13 IB of the second engine I 30B, e.g. via a third air supply piping 123 as exemplarily shown in Fig. 6. In particular, the third air supply piping 123 may include a second charge air cooler 170B. As exemplarily shown in Fig. 6, the exhaust gas piping 140 may be configured for providing exhaust gas form the first engine 130 A and the second engine 130B to the first turbine 112A and the second turbine 112B.

[0048] It is to be noted, that according to embodiments which can be combined with other embodiments described herein, the air supply apparatus 100 may include an engine with two cylinder banks. For example, the engine with two cylinder banks can be a V-engine. For instance, Fig. 6 can also be interpreted in that ‘ 130A’ indicates a first cylinder bank 130 A and ‘ BOB’ indicates a second cylinder bank of a V-engine.

[0049] With exemplary reference to Figs. 7 and 8, according to embodiments, which can be combined with other embodiments described herein, the air supply apparatus 100 may include a serial multi -turbo configuration with two or more turbochargers in series. In particular, Figs. 7 and 8 show exemplarily embodiments with a two-stage serial turbocharger configuration, having a first turbocharger 110A and a second turbocharger 110b. For example, the first turbocharger 110A can be a high- pressure turbocharger and the second turbocharger HOB can be a low- pressure turbocharger. As exemplarily shown in Fig. 7, the firstturbocharger 110A may include a first electric machine 151 or be a standard turbocharger as shown in Fig. 8. Further, the second turbocharger HOB can include a second electric machine 152, as exemplarily shown in Figs. 7 and 8. Alternatively, the second turbocharger HOB may be a standard turbocharger (not explicitly shown in Figs. 7 and 8)

[0050] With exemplary reference to Fig. 7, according to embodiments, which can be combined with other embodiments described herein, an intercooler 171 may be provided between the first compressor 111 A and the second compressor 11 IB. As exemplary shown in Fig. 8, a fourth air supply piping 124 may be provided for providing air to the air-powered device 160. In particular, the fourth air supply piping 124 may be connected upstream and / or downstream of the intercooler 171.

[0051] With exemplary reference to Figs. 2 and 3, it is to be understood that according to a further aspect of the present disclosure, a ship 200 including an air supply apparatus 100 according to any embodiments described herein is provided. It is to be understood, that the “air supply apparatus” can be configured to supply air to one or more air-powered devices. Typically, at least one of the one or more air-powered devices is an air lubrication device.

[0052] With exemplary reference to the block diagram shown in Fig. 9, embodiments of a method 300 of supplying air to an air-powered device 160 according to the present disclosure is described. According to embodiments, which can be combined with other embodiments described herein, the method 300 includes driving (represented by block 310 in Fig. 9) a compressor 111 of a turbomachine 110 for charging an engine 130 by using an electric machine 150. Additionally, the method 300 includes adjusting (represented by block 320 in Fig. 9) the compressor’s aerodynamic characteristics to the airflow through passing through the compressor 111 by utilizing a variable compressor geometry 11V. Further, the method 300includes supplying (represented by block 330 in Fig. 9) air from the compressor 111 via an air supply system 120 to the air-powered device 160.

[0053] According to embodiments, which can be combined with other embodiments described herein, the method 300 further includes controlling (represented by block 340 in Fig. 9) an amount of air provided to the air- powered device 160 by controlling an amount of engine intake air. Additionally, or alternatively, the amount of air provided to the air-powered device 160 may be controlled by using one or more elements provided in the air supply system 120. The one or more elements can be selected from the group consisting of a valve 181, an expander 182, and a tank 183 for storing pressurized air, particularly as exemplarily described with reference to Fig. 3.

[0054] According to embodiments, which can be combined with other embodiments described herein, the method 300 further includes converting (represented by block 350 in Fig. 9) mechanical energy into electrical energy by using a generator coupled to a turbine 112 of the turbomachine 110.

[0055] It is to be understood that the method 300 of supplying air to an air- powered device 160 can be conducted by employing an air supply apparatus 100 according to any embodiments described herein.

[0056] In view of the embodiments described herein, it is to be understood compared to the state of the art, improved apparatuses and methods for operating an air-powered device are provided, particularly with respect to energy efficiency.

[0057] In particular, it is to be noted that an air lubrication device, requires a given air mass flow and pressure, respectively depending on the speed and the draft depth. An idea to avoid installing expensive dedicated compressor(s) - or to reduce their number / size - can be to take the air from the turbocharger compressor outlet - before or after the charge air cooler - as described herein.

[0058] The main challenge of this solution comes from the limitations of the turbocharging system, particularly with respect to compressor(s) map(s) width, turbine(s) power and turbocharging efficiency.

[0059] When the turbine is matched to the engine, its power is not sufficient to allow the compressor to full fill the hull lubrication required, especially if the compressor has to be defined with a larger size than if it had to only supply the engine. An option can be to add a variable geometry device on the turbine, or to match a smaller area turbine with a waste-gate, but this increases the back pressure of the engine at a level often above a limit that the engine can afford (e.g., 4-stroke, but especially 2-stroke) or reduces the air flow (e.g., 2- stroke) below an allowable limit.

[0060] The present invention according to embodiments described herein do not face the problem of a too narrow compressor map and / or too small compressor size (not enough swallowing capacity) and / or insufficient turbocharger power, particularly due to the possibility of compensating the power lack with an electric machine (eTurbo) by injecting electrical power to the rotor / turbocharging system (PTI) and / or exhaust gas energy recovery (PTO). The invention also allows adjusting the right compressor speed according to the operation mode (engine load and / or air powered system requirement like air bubble lubrication flow)

[0061] While the foregoing is directed to embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope is determined by the claims that follow.REFERENCE NUMBERS100 air supply apparatus101 air intake102 exhaust outlet110 turbomachine110A first turbochargerHOB second turbocharger111 compressor11 V variable compressor geometry11 VAvariable compressor geometry of the first compressor11 VBvariable compressor geometry of the second compressor111 A first compressorl 1 IB second compressor112 turbine112A first turbine112B second turbine113 shaft120 air supply system121 first air supply piping122 second air supply piping123 third air supply piping124 fourth air supply piping130 engine130A first engine130B second engine131 intake manifold131 A first intake manifold13 IB second intake manifold140 exhaust gas piping150 electric machine151 first electric machine152 second electric machine153 controller160 air-powered device170 charge air cooler170A first charge air cooler170B second charge air cooler171 intercooler181 valve182 expander183 tank190 inflatable sail system191 pressure control device200 ship300 method of supplying air to an air-powered device310, 320 330, 340 bocks representing method steps as described in the present disclosure

Claims

CLAIMS1. An air supply apparatus (100), comprising:- a turbomachine (110) having a compressor (111) and a turbine (112), wherein the compressor (111) comprises a variable compressor geometry (11V), wherein the compressor (111) is connected with an engine (130) via an air supply system (120), and wherein the turbine (112) is connected with the engine (130) via an exhaust gas piping (140);- at least one electric machine (150) coupled to at least one of the compressor (111) and the turbine (112); and- an air-powered device (160) connected with the air supply system (120).

2. The air supply apparatus (100) of claim 1, wherein the at least one electric machine (150) is an electric motor-generator configured to convert electrical energy into mechanical energy and vice versa.

3. The air supply apparatus (100) of claim 1 or 2, wherein the compressor (111) and the turbine (112) are connected via a shaft (113), and wherein the at least one electric machine (150) is arranged between the compressor (111) and the turbine (112), or on the compressor side and coupled to the compressor (111).

4. The air supply apparatus (100) of claim 1 or 2, wherein the turbomachine (110) is a shafted turbocharger or a non-shafted turbocharger.

5. The air supply apparatus (100) of claim 4, wherein the at least one electric machine (150) comprises a first electric machine (151) coupled to the compressor (111) and a second electric machine (152) coupled to the turbine (112), particularly wherein the first electric machine (151) is a motor and the second electric machine (152) is a generator.

6. The air supply apparatus (100) of claim 4 or 5, wherein the first electric machine (151) and the second electric machine (152) are connected with a controller (153) for controlling the first electric machine (151) and the second electric machine (152).

7. The air supply apparatus (100) of any of claims 1 to 6, wherein the air supply system (120) comprises a first air supply piping (121) for supplying air to an intake manifold (131) of the engine (130), and a second air supply piping (122) connecting the air-powered device (160) with the first air supply piping (121) and / or the intake manifold (131).

8. The air supply apparatus (100) of claim 7, wherein the first air supply piping (121) includes a charge air cooler (170), particularly the second air supply piping (122) is connected with the first air supply piping (121) upstream and / or downstream of the charge air cooler (170).

9. The air supply apparatus (100) of any of claims 1 to 8, wherein the air supply system (120) comprises one or more elements selected from the group consisting of: a valve (181) to control air mass flow from the compressor (111) to the air-powered device (160); an expander (182) to expand pressurized air and to convert internal energy of the pressurized air into mechanical or electrical energy; and a tank (183) for storing pressurized air.

10. The air supply apparatus (100) of any of claims 1 to 9, wherein the air- powered device (160) comprises an air lubrication device for resistance reduction of a ship and / or an inflatable sail system (190).

11. The air supply apparatus (100) of any of claims 1 to 10, wherein the variable compressor geometry (11 V) comprises at least one of adjustable inlet guide vanes and adjustable diffuser vanes.

12. The air supply apparatus (100) of any of claims 1 to 10, the air supply system (120) comprising a pressure control device (191), particularly when the air supply system (120) is connected to an inflatable sail system (190).

13. A ship (200) comprising an air supply apparatus (100) according to any of claims 1 to 12.

14. A method (300) of supplying air to an air-powered device (160), comprising:- driving (310) a compressor (111) of a turbomachine (110) for charging an engine (130) by using an electric machine (150),- adjusting the compressor’s aerodynamic characteristics to an airflow through the compressor (111) by utilizing a variable compressor geometry (11 V), and- supplying (320) air from the compressor (111) via an air supply system (120) to the air-powered device (160).

15. The method (300) of claim 14, further comprising controlling (330) an amount of air provided to the air-powered device (160) by controlling an amount of engine intake air and / or using one or more elements provided in the air supply system (120), the one or more elements being selected from the group consisting of a valve (181), an expander (182), and a tank (183) for storing pressurized air.

16. The method (300) of claim 14 or 15, further comprising converting (340) mechanical energy into electrical energy by using a generator coupled to a turbine (112) of the turbomachine (110).

17. The method (300) of any of claims 14 to 16, wherein the method is conducted by employing an air supply apparatus (100) according to any of claims 1 to 12.

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