High-speed machine

Abstract

A high-speed machine 200 comprises a compressor 204 having a shaft assembly 206, a cooling system 202 and a housing 203. The cooling system and shaft assembly are located within the housing, and the c

Description

Field of the invention The present invention relates to a high-speed machine. Background to the invention High-speed machines, such as compressors and turbochargers, can be configured to provide a compressed air stream to a downstream system such as an engine or other power system, or a turbine. The compression of air in the high-speed machine raises the temperature of the compressed air stream. To increase air stream density and improve the efficiency and / or power density of the power system, it is desirable to cool the compressed air stream prior to entry into the power system. Charge-air coolers can be employed to cool the compressed air generated by a high-speed machine. However, the air stream exiting the high-speed machine must pass through the charge-air cooler resulting in pressure losses and increase the air path volume, thereby decreasing the efficiency of the high-speed machine. Additionally, charge-air coolers are bulky and increase the weight of the high-speed machine system. It is desirable to ensure the temperature of components of the high-speed machine are not raised above acceptable internal operating limits, to prolong the lifespan of the high-speed machine. Objects and aspects of the present invention seek to alleviate at least these problems with the prior art. Summary of the Invention According to a first aspect of the invention, there is provided a high-speed machine, the highspeed machine comprising; a compressor comprising a shaft assembly; a cooling system; and a housing; wherein the cooling system and the shaft assembly are located within the housing; and wherein the cooling system is configured, in use, to cool both a portion of the shaft assembly and a fluid stream exiting the compressor. In this way, there is provided a high-speed machine with an integrated cooling system configured to cool both a compressed air stream exiting the compressor and a portion of the shaft assembly of the compressor. Further, the high-speed machine of the present invention benefits from reduced complexity, part count, and packaging as well as an improvement in the steady state efficiency and transient performance due to reducing the path pressure losses and volume of the fluid stream exiting the compressor. In some embodiments, the high-speed machine is a non-electrical high-speed machine. Preferably, the shaft assembly comprises a compressor bearing assembly comprising at least one bearing. Preferably, the shaft assembly comprises a shaft configured to be coupled to a drive assembly configured to rotate the shaft of the compressor. In some embodiments, the high-speed machine is an electrical high-speed machine. Preferably, the electrical high-speed machine is an electric turbocharger or electric compressor. Preferably, the shaft assembly comprises a compressor bearing assembly comprising at least one bearing. Preferably, the shaft assembly comprises an electric motor. Preferably, the electric motor comprises a rotor and a stator. It is understood that a fluid may be any suitable liquid or gas. By integrating the cooling system within the housing, no external charge-air cooler or external cooling jacket is required. Therefore, a reduced air path volume is provided through which the compressed air stream passes, leading to reduced pressure losses experienced by the compressed air stream through the high-speed machine. The efficiency of the high-speed machine is increased, the size requirements are reduced, and fewer connections are required to provide the compressed air stream path through the high-speed machine. The high-speed machine is particularly advantageous for use in combined heat and power (CHP) systems. The fluid that is to be compressed by the compressor depends on the use and deployment of the high-speed machine. Typically, the compressor is configured to compress air, however other fluids may also be compressed. Additionally, integrating the cooling system into the housing means that, in use, the coolant fluid flows through locations closer to the heat-generating components of high-speed machine, such as portions of the shaft assembly, such as the compressor bearing system and stator, and therefore cool the high-speed machine more efficiently. Thus, it is envisaged that the rate of flow or the volume of the coolant fluid can be decreased to achieve the same cooling effect. Preferably, the high-speed machine further comprises power electronics, wherein the cooling system is configured, in use, to cool the power electronics. Power electronics generate heat, in use, and it is therefore desirable to cool the power electronics to ensure acceptable internal operating temperatures of the compressor and power electronics are maintained. Preferably, the high-speed machine further comprises a turbine. In some embodiments, the turbine is configured to receive a fluid stream from a power system. A turbine may be configured to rotate the compressor. In particular, the turbine can be configured to receive an exhaust air stream from the power system, such as an engine, to rotate the turbine blades. In this way, the presence of a turbine increases the heat recover potential of the high-speed machine, allowing hot exhaust air from a power system to be recovered and re-used. In some embodiments, a fluid stream from the cooling system is configured to enter the turbine. Namely, the exhaust fluid stream from the compressor is configured to enter the turbine after the fluid stream has been cooled by the cooling system. Most advantageously, such a configuration forms a reverse Brayton cycle, wherein the fluid stream exiting the turbine is at a lower temperature compared to the fluid stream entering the compressor. In this way, the overall temperature across the high-speed machine is reduced. In this way, the cooling system is configured to cool a fluid stream entering the turbine. As such, the temperature of the fluid stream exiting the turbine is at a lower temperature compared to the fluid stream entering the compressor, such that a reverse Brayton cycle is provided. In some embodiments, a fluid stream is configured to pass through each of the compressor, the cooling system and the turbine. Alternatively, a fluid stream from the cooling system is configured to enter a second compressor. As such, interstage cooling is provided which improves the overall compression efficiency. Preferably, the compressor is a first compressor and the high-speed machine further comprises a second compressor. Preferably, the first compressor is coupled to the second compressor by the shaft assembly of the first compressor. In this way, the high-speed machine comprises a two-stage electric compressor (eCompressor). Preferably, the highspeed machine further comprises a second cooling system located between the first compressor and the second compressor. More preferably, the second cooling system is located within the housing. In this way, the cooling systems are integrated within the housing. In some embodiments, the high-speed machine further comprises an intercooler connecting the first compressor to the second compressor, wherein the intercooler is configured to cool exhaust air exiting the first compressor. Further, the housing of the high-speed machine can be manufactured using additive manufacturing methods, such as 3D printing. The housing can be manufactured as a single unit, thereby reducing complexity, footprint, number of associated failure points, cost, assembly time, installation time, part count, size, volume and weight. The ease of manufacture of the high-speed machine is also improved. Preferably, the cooling system comprises a spiral component. It is understood that a spiral shape may be any curved or helical shape following a straight and / or curving central axis. The pitch of the spiral component may be constant or may vary along the length of the spiral. In this way, spiral in shape should not be limited to concentric shapes, provided that the path of the spiral is wrapped about a central axis. Preferably, the spiral is concentric about a central axis. Preferably, the spiral component comprises at least one longitudinal channel projecting in a direction parallel to the central axis. Preferably, the at least one longitudinal channel comprises a plurality of longitudinal channels. Preferably, the spiral component comprises at least one spiral channel projecting in a direction around central axis. For example, the at least one spiral channel may project concentrically about the central axis. Preferably, the at least one spiral channel comprises a plurality of spiral channels. It is understood that the term ‘longitudinal1 channel refers to a channel projecting in the longitudinal direction of the spiral component, namely along the central axis. The at least one longitudinal channel comprises a shorter path length than the at least one spiral channel due to the relative lack of curves or bends along its length compared to the spiral channel. The at least one longitudinal channel may itself comprise curves, bends or turns, and is not required to be entirely straight along its length. Preferably, the at least one longitudinal channel or the at least one spiral channel is configured to receive a compressed fluid stream exiting the compressor. In this way, a compressed fluid stream exiting the compressor can pass through either the at least one longitudinal or at least one spiral channel to be cooled by the cooling system. Preferably, the at least one longitudinal channel or the at least one spiral channel is configured to receive a flow of coolant fluid. Preferably, at least one longitudinal channel is located adjacent at least one spiral channel. In this way, coolant fluid can be introduced into the longitudinal or spiral channel, thereby permitting efficient heat exchange between the compressed air stream in the at least one longitudinal channel or the at least one spiral channel and the coolant fluid in the other of the channels. An efficient fluid-fluid, such as airliquid or air-air, heat exchanger can therefore be provided. Preferably, the spiral channel comprises an outer facing wall and the outer facing wall is continuous along the length of the spiral channel. Preferably, the pitch of the spiral channel is substantially constant along the length of the spiral channel. Preferably, the radius of the spiral channel is constant along the length of the spiral channel. In this way, a concentric spiral shape is provided by the spiral channel. Preferably, the at least one spiral channel is configured to be fluidly connected to a power system. In this way, a cooled compressed fluid stream exiting the compressor and passing through the spiral channel can enter a power system, such as an engine. Alternatively, the at least one longitudinal channel is configured to be fluidly connected to a power system. In this way, a cooled compressed fluid stream exiting the compressor and passing through the longitudinal channel can enter a power system, such as an engine. Preferably, the spiral component comprises a plurality of stacked layers. In this way, a multilayered cooling system is provided. Preferably, each layer of the plurality of stacked layers comprises at least one longitudinal channel or at least one spiral channel. Preferably, each layer of the plurality of stacked layers contacts the one or more adjacent layer / s of the plurality of stacked layers. In this way, no gaps are provided between the plurality of stacked layers, reducing the size of the cooling system. Preferably, each layer comprising a spiral channel is sandwiched between a first adjacent layer comprising a longitudinal channel and a second adjacent layer comprising a longitudinal channel. Similarly, preferably, each layer comprising a longitudinal channel is sandwiched between a first adjacent layer comprising a spiral channel and a second adjacent layer comprising a spiral channel. Preferably, the spiral component comprises a minimum of two stacked layers, one layer comprising a longitudinal channel and one layer comprising a spiral channel, or one layer comprising a first longitudinal channel and one layer comprising a second longitudinal channel. Preferably, the spiral component comprises an innermost layer and an outermost layer, wherein the innermost layer is located closest to the central axis and the outermost layer is located distal to the central axis. The composition of the innermost layer and outermost layer is not essential to the function of the invention. Alternatively, the cooling system comprises a cylindrical component. Preferably, the cylindrical component comprises at least one first longitudinal channel and at least one second longitudinal channel. Preferably, the at least one first longitudinal channel projects in a direction parallel to the central axis. Preferably, the at least one first longitudinal channel comprises a plurality of longitudinal channels. Preferably, the at least one second longitudinal channel projects in a direction parallel to the central axis and in an opposing direction to that of the first longitudinal axis. Preferably, the at least one second longitudinal channel comprises a plurality of longitudinal channels. In this way, the at least one first longitudinal channel is substantially parallel to the at least one second longitudinal channel. Preferably, the at least one first longitudinal channel is configured to receive a compressed fluid stream exiting the compressor. In this way, a compressed fluid stream exiting the compressor can pass through the at least one first longitudinal channel to be cooled by the cooling system. Preferably, the at least one second longitudinal channel is configured to receive a flow of coolant fluid. Preferably, at least one first longitudinal channel is located adjacent at least one second longitudinal channel. In this way, coolant fluid can be introduced into the at least one second longitudinal channel, thereby permitting efficient heat exchange between the compressed air stream in the at least one first longitudinal channel and the coolant fluid in the at least one second longitudinal channel. An efficient fluid-fluid, such as air-liquid or air-air, heat exchanger can therefore be provided. Preferably, the at least one first longitudinal channel is configured to be fluidly connected to a power system. In this way, a cooled compressed fluid stream exiting the compressor and passing through the at least one first longitudinal channel can enter a power system, such as an engine. Preferably, the cylindrical component comprises a plurality of stacked layers. In this way, a multi-layered cooling system is provided. Preferably, each layer of the plurality of stacked layers comprises at least one first longitudinal channel or at least one second longitudinal channel. Preferably, each layer of the plurality of stacked layers contacts the one or more adjacent layer of the plurality of stacked layers. In this way, no gaps are provided between the plurality of stacked layers, reducing the size of the cooling system. Preferably, each layer comprising a first longitudinal channel is sandwiched between a first adjacent layer comprising a second longitudinal channel and a second adjacent layer comprising a second longitudinal channel. Similarly, preferably, each layer comprising a second longitudinal channel is sandwiched between a first adjacent layer comprising a first longitudinal channel and a second adjacent layer comprising a first longitudinal channel. Preferably, the cylindrical component comprises an innermost layer and an outermost layer, wherein the innermost layer is located closest to the central axis and the outermost layer is located distal to the central axis. The composition of the innermost layer and outermost layer is not essential to the function of the invention. In some embodiments, the cooling system comprises at least one spiral component and at least one cylindrical component. Preferably, wherein the machine is an electrical machine, the cooling system is configured to encase a stator of the shaft assembly. Preferably, the cooling system is configured to encase a compressor bearing assembly of the shaft assembly. The stator and bearings of the shaft assembly generate heat during use. In this way, the cooling system is located adjacent to a heat generating component of the compressor, improving heat transfer away from the compressor. In some embodiments, the at least one longitudinal channel or the at least one first longitudinal channel is arranged perpendicular to the stator of the shaft assembly. In this way, the longitudinal axis of the spiral component or the longitudinal axis of the cylindrical component are arranged perpendicular to the shaft of the shaft assembly. Alternatively, the at least one longitudinal is or the at least one first longitudinal channel arranged parallel to the stator of the shaft assembly. In this way, the longitudinal axis of the spiral component or the longitudinal axis of the cylindrical component are arranged parallel to the shaft of the shaft assembly. Detailed Description Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 depicts an electric turbomachine according to the prior art; Figure 2 depicts a perspective view of a high-speed machine according to the first aspect of the present invention; Figure 3 depicts a second electric machine according to the prior art; Figure 4 depicts a second embodiment of a high-speed machine according to the first aspect of the present invention; Figure 5 depicts an electric compressor according to the prior art; Figure 6 depicts a third embodiment of a high-speed machine according to the first aspect of the present invention; Figure 7 depicts a two-stage electric compressor according to the prior art; Figure 8 depicts a fourth embodiment of a high-speed machine according to the first aspect of the present invention; Figure 9A depicts a first embodiment of a spiral component according to the first aspect of the present invention; Figure 9B depicts a section view of the spiral component of Figure 9A; Figure 10A depicts a second embodiment of a cylindrical component according to the first aspect of the present invention; and Figure 10B depicts a section view of the cylindrical component of Figure 10A. With reference to Figure 1, there is illustrated an electric turbomachine 100 of the prior art, and therefore falling outside the scope of this invention. The turbomachine 100 is fluidly connected to a power system 101 comprising an engine. The turbomachine 100 is also fluidly connected to a charge-air cooler 102, located outside a housing 103 of the turbomachine 100. The charge-air cooler 102 is also fluidly connected to the power system 101 such that a fluid stream may pass from the turbomachine 100 to the power system 101 via the charge-aircooler 102. The turbomachine 100 comprises a compressor 104 powered by a turbine 105. The housing 103 of the turbomachine 100 houses the compressor 104 and the turbine 105. The turbomachine 100 further comprises power electronics (not shown), which may be located within the housing 103 or may be located outside of the housing 103 and configured to power components of the compressor 104 and turbine 105. The compressor 104 is configured to compress a fluid stream, such as a stream of air, entering the compressor 104 through compressor fluid inlet 104a. The compressed fluid stream then exits the turbomachine 100 via compressor fluid outlet 104b. The compressor fluid outlet 104b is fluidly connected to the external charge-air cooler 102, and the compressed fluid stream passes through the charge-air cooler 102 where it is cooled before entering the power system 101. The charge-air cooler 102 comprises a coolant inlet 102a configured to receive a coolant fluid, such as water, and a coolant outlet 102b. The charge-air cooler 102 acts as a heat exchanger, providing a coolant fluid stream to remove excess heat from the compressed fluid stream, thereby cooling the compressed fluid stream prior to entry into the power system 101. An exhaust fluid stream from the power system 101 is configured to enter the turbomachine 100 via a turbine fluid inlet 105a. The exhaust fluid stream is configured to rotate the turbine 105 and then exit the turbomachine 100 via turbine fluid outlet 105b. The compressor 104 is coupled to the turbine 105 such that rotation of the turbine 105 drives the compressor 104. The compressor 104, turbine 105 and power electronics generate heat during use. The housing 103 comprises a housing coolant inlet 103a, configured to receive a coolant fluid stream, and a housing coolant outlet 103b. By injecting a coolant fluid stream into the housing 103, the contents of the housing 103can be cooled via heat exchange between the heated air around these components, or through direct contact with the components themselves, and the coolant fluid stream arranged to pass through and subsequently exit the housing 103 when the coolant fluid stream has been heated. There are numerous disadvantages with the turbomachine 100 of the prior art. The compressed fluid stream exiting the turbomachine 100 must pass through the external chargeair cooler 102, which increases the distance the fluid must travel resulting in losses in transient response time due to an increase in the path volume of the fluid stream. Therefore, efficiency of the turbomachine 100 is limited. Additionally, charge-air coolers 102 are bulky and increase the weight and size of the turbomachine 100 system. Turning to Figure 2, a high-speed machine 200 according to the present invention will now be described. In the following description, similar numerals will be used for similar parts of an embodiment of the present invention and the improvements over the turbomachine 100 of the prior art will be outlined. The high-speed machine 200 is an electric turbomachine. The turbomachine 200 is fluidly connected to a power system 201, such as an engine. The turbomachine 200 comprises a compressor 204 and a turbine 205 configured to drive the compressor 204. A housing 203 of the turbomachine 200 houses the compressor 204, the turbine 205 and power electronics (not shown) configured to power the compressor 204 and turbine 205. The compressor 204 is coupled to the turbine 205 via a shaft assembly 206 comprising a stator 206a, a rotor 206b and a compressor bearing assembly 206c. The shaft assembly 206 further comprises compressor and turbine casings configured to protect the rotor and stator from the compressor and turbine heat. The housing 203 surrounds the shaft assembly 206. Optionally, the housing 203 may surround the compressor 204, the turbine 205 and / or, in some embodiments, the power electronics. Alternatively, to aid assembly of the turbomachine 200, the housing around the compressor 204, the turbine 205 and the power electronics are separate to housing 203. The compressor 204 is configured to compress a fluid stream, such as a stream of air, entering the compressor 204 through compressor fluid inlet 204a. The fluid stream is heated during compression, thereby providing a ‘hot’ compressed fluid stream. However, instead of exiting the turbomachine after compression, as in the prior art turbomachine 100 of Figure 1, the hot compressed fluid stream is configured to enter a cooling system 202 located within the housing 203. The cooling system 202 (or as it may also be known the cooling circuit) is integrated within the housing 203 in that the coolant fluid used to cool the shaft assembly 206 components, in use, flows through the internal walls of housing 203. The cooling system 202 removes heat from the hot compressed fluid stream, thereby transforming the fluid stream into a ‘cool’ fluid stream. The terms ‘hot and ‘cool’ are understood to refer to the relative temperature of the compressed fluid stream before and after cooling by the cooling system 202. The cooling system 202 is located within the housing 203. The cooling system may comprise either the spiral component of Figure 9 or the cylindrical component of Figure 10. The cooling system 202 acts as a heat exchanger, providing a coolant fluid stream to remove excess heat from the hot compressed fluid stream. The cooling system 202 is configured to encase and cool at least a portion of the shaft assembly 206 via heat transfer. The stator 206a of the shaft assembly 206 may generate heat during use. The cooling system 202 comprises a coolant inlet 202a, configured to receive a coolant fluid stream, and a coolant outlet 202b. By injecting a coolant fluid stream into the cooling system 202, the stator 206a (in embodiments where the power electronics are located within the housing 203) can be cooled via heat exchange between the heated air around the stator assembly and the coolant fluid stream located within the housing 203. The configuration of the cooling system 202 will be described further in relation to Figures 9-10. After passing through the cooling system 202, the cool compressed fluid stream exits the turbomachine 200 via cool fluid outlet 204b. The cool fluid outlet 204b is fluidly connected to the power system 201 and the cool compressed fluid stream enters the power system 201 after exiting the turbomachine 200. In this way, the power system 201 is provided with a cool compressed fluid stream without requiring an external charge-air cooler. An exhaust fluid stream from the power system 201 is configured to enter the turbomachine 200 via a turbine fluid inlet 205a. The exhaust fluid stream is configured to rotate the turbine 205 and then exit the turbomachine 200 via turbine fluid outlet 205b. The compressor 204 is coupled to the turbine 205 such that rotation of the turbine 205 drives the compressor 204. In this way, there is provided a turbomachine 200 with an integrated cooling system 202 configured to cool both the hot compressed fluid stream produced by the compressor 204 and at least a portion of the shaft assembly 206 such as the stator 206a. A smaller, lighter, more efficient turbomachine with charge air cooling is provided. High-speed machines have a very high lifetime requirement, without component replacement, to be economically and practically viable. As such, it is important that all components of the high-speed machine, such as the shaft assembly and power electronics are kept below their heat rating. Thus, providing adequate cooling to the high-speed machine and its associated components is vital. In general, housings of high-speed machines are fabricated from metal so the housing possess good or excellent thermal conductivity. Thus, the housing 203 itself can conduct heat from the heat-generating components of the high-speed machines to the integrated cooling system 202. As such, the present invention efficiently uses previously dead or wasted space within the housing 203. With reference to Figure 3, a reverse Brayton cycle high-speed machine, such as an air dryer, heat pump or refrigerating machine, 300 of the prior art is illustrated. The machine 300 comprises a compressor 304, a turbine 305 and, optionally, the power electronics (not shown) housed within a housing 303. The turbomachine 300 is fluidly connected to a charge-air cooler 302. The machine 300 of Figure 3 is substantially identical to the turbocharger 100 of Figure 1 with the following differences. A cooled exhaust air stream exits the charge-air cooler 302 via outlet 302c and, instead of entering a power system such as an engine, the cooled exhaust air stream is configured to reenter the machine 300 via turbine fluid inlet 305a. In this way, the charge-air cooler 302 is fluidly connected to the turbine 305. The cool exhaust air stream can then be configured to rotate the turbine 305, thereby powering the compressor 304. With reference to Figure 4, a second embodiment of a high-speed machine 400 according to the first aspect of the invention is illustrated. The high-speed machine 400 is a reverse Brayton cycle machine comprising a compressor 404 comprising a shaft assembly 406, turbine 405 and, optionally, power electronics (not shown) located within a housing 403. As with the shaft assembly 206 of Figure 2, the shaft assembly 406 comprises a stator, a rotor, a compressor bearing assembly and casings configured to protect the rotor and stator from the compressor and turbine heat. A cooling system 402 is integrated within the housing 403. The machine 400 of Figure 4 is substantially identical to the turbocharger 200 of Figure 2 with the following differences. The machine 400 is not fluidly connected to a power system. Instead, a fluid stream, such as an air stream, enters the turbomachine 400 via compressor fluid inlet 404a. The fluid stream is compressed by the compressor 404 and the hot compressed fluid stream from the compressor 404 enters, and is cooled by, the cooling system 402. The cool compressed fluid stream is then configured to flow directly into the turbine 405, without requiring an external charge-air cooler. The exhaust fluid stream from the turbine 405 then expands and exits the turbomachine 400 via turbine fluid outlet 405b at a lower temperature than the fluid stream entered the turbomachine 400 via compressor fluid inlet 404a. In this way, the cool compressed fluid stream can power the turbine 405 which in turn powers the compressor 404. The cooling system 402 further cools the shaft assembly 406, during use. In this way the power demand of the compressor is reduced. The temperature of the exhaust air stream is reduced as the air stream expands through the turbine 405. In this way, the temperature of the fluid stream exiting the turbine 405 is lower than the temperature of the fluid stream entering the compressor 404, such that a reverse Brayton cycle machine is provided. Further, the expansion of the fluid stream within the turbine 405 helps to reduce the power requirement to drive the compressor 404. With reference to Figure 5, an electric compressor 500 of the prior art is illustrated. The electric compressor 500 comprises a compressor 504 and, optionally, power electronics (not shown) encased within a housing 503. The electric compressor 500 is fluidly connected to a chargeair cooler 502, and the charge-air cooler 502 is fluidly connected to a power system 501, such as a proton-exchange membrane (PEM) fuel cell ora solid oxide fuel cell (SOFC). The electric compressor 500 of Figure 5 is substantially identical to the turbocharger 100 of Figure 1 with the following differences. The electric compressor 500 does not comprise a turbine. Instead, the compressor 504 is powered by alternative drive means, such as an electrical machine. As such, there is no exhaust fluid exiting the power system 501 and entering the electric compressor 500. The electric compressor 500 further comprises a shaft assembly 506 similar to that of the embodiments of Figures 1 and 3. With reference to Figure 6, a third embodiment of a high-speed machine 600 according to the first aspect of the invention is illustrated. The high-speed machine 600 is an electric compressor comprising a compressor 604 comprising a shaft assembly 606, similar to the shaft assembly of the embodiments of Figures 2 and 4, and power electronics (not shown) located within a housing 603. A cooling system 602 is integrated within the housing 603. The electric compressor 600 is fluidly connected to a power system 601, such as a protonexchange membrane (PEM) fuel cell or a solid oxide fuel cell (SOFC). The electric compressor 600 of Figure 6 is substantially identical to the turbocharger 200 of Figure 2 with the following differences. The electric compressor 600 does not comprise a turbine. Instead, the compressor 604 is powered by a motor, such as an electric motor, of the shaft assembly 606. As such, there is no exhaust fluid exiting the power system 601 and entering the electric compressor 600. The fluid stream is compressed by the compressor 604 and the hot compressed fluid stream from the compressor 604 enters, and is cooled by, the cooling system 602. The cool compressed fluid stream is then configured to exit the electric compressor 600 via cool fluid outlet 604b and be passed into the power system 601. There is no requirement for an external charge-air cooler to cool the compressed fluid stream exiting the compressor 604, as the integrated cooling system 602 provides the required heat exchange the cool the fluid stream. The cooling system 602 further cools the shaft assembly 606 and, optionally, power electronics, during use. With reference to Figure 7, an electric compressor 700 of the prior art is illustrated. The electric compressor 700 comprises a first compressor 704’ fluidly connected to a second compressor 704”. In this way, a two-stage electric compressor is provided. The electric compressor 700 further comprises power electronics (not pictured), and the first compressor 704’ and second compressor 704” are housed within a housing 703. The electric compressor 700 is fluidly connected to an external charge-air cooler 702, and the charge-air cooler 702 is fluidly connected to a power system 701, such as an engine. The electric compressor 700 of Figure 7 is substantially identical to the turbocharger 100 of Figure 1 with the following differences. The electric compressor 700 does not comprise a turbine. Instead, the first compressor 704’ and second compressor 704” are powered by alternative drive means (not pictured). As such, there is no exhaust fluid exiting the power system 701 and re-entering the electric compressor 700. The first compressor 704’ is configured to compress a fluid stream entering the first compressor 704’ via a first compressor fluid inlet 704a’. The electric compressor 700 optionally comprises a second cooling system comprising an interstage pipe 707 located between and fluidly connecting the first compressor 704’ to the second compressor 704”The interstage pipe 707 is connected to a second compressor fluid inlet 704a” of the second compressor 704”, wherein the fluid stream exits the interstage pipe 707 and is compressed further by the second compressor 704”. The compressed air stream is then passed through the charge-air cooler 702 as described above. With reference to Figure 8, a fourth embodiment of a high-speed machine 800 according to the first aspect of the invention is illustrated. The high-speed machine 800 is two-stage electric compressor comprising a first compressor 804’ coupled to a second compressor 804” via a shaft assembly 806; and optionally, power electronics (not shown) located within a housing 803. A cooling system 802 is integrated within the housing 803. The electric compressor 800 of Figure 8 is substantially identical to the turbocharger 200 of Figure 2 with the following differences. The electric compressor 800 does not comprise a turbine. Instead, the first compressor 804’ and second compressor 804” are configured to be powered by the shaft assembly 806. As such, there is no exhaust fluid exiting the power system 801 and re-entering the electric compressor 800. The first compressor 804’ is configured to compress a fluid stream entering the first compressor 804’ via first compressor fluid inlet 804a’. The electric compressor 800 further comprises an interstage pipe 807 fluidly connecting the first compressor 804’ to the second compressor 804”. The interstage pipe 807 is connected to a second compressor fluid inlet 804a” of the second compressor 804”, wherein the fluid stream exits the interstage pipe 807 and is compressed by the second compressor 804”. The hot compressed air stream is then passed through the cooling system 802 wherein it is cooled via heat exchange, as described in relation to Figures 9 and 10 below. The cool compressed fluid stream is then configured to exit the electric compressor 800 via cool fluid outlet 804b, without requiring an external charge-air cooler. The cooling system 802 further cools at least a portion of the shaft assembly 806, such as the stator, and, optionally, the power electronics, during use. The cooling system of Figures 2, 4, 6 and 8 will now be described in further detail, with reference to Figures 9 and 10. Figure 9A illustrates a spiral component 900 of a cooling system of the first aspect of the invention. The spiral component 900 is configured to project substantially the entire length of the cooling system. The spiral component 900 comprises a plurality of longitudinal channels 910, a plurality of spiral channels 920 and a central aperture 903 extending along a central axis C of the spiral component 900. The pitch of the spiral component 900 is substantially constant along its length. A component of the shaft assembly, such as the stator, is configured to be housed within the central aperture 903. In this embodiment, the spiral component 900 comprises three longitudinal channels 910, each longitudinal channel 910 projecting in a direction parallel to the central axis C, and two spiral channels 920, each spiral channel 920 projecting concentrically about the central axis C. The spiral component 900 is located within the housing of the high-speed machine and can be fluidly connected to a compressor fluid outlet. In some embodiments, the longitudinal channels 910 are configured to receive a fluid stream exiting a compressor, such as the compressor 204, 404, 604, 804” of the embodiments of Figures 2, 4, 6 and 8, and the spiral channels 920 are configured to receive a flow of coolant fluid. In this way, a hot compressed fluid stream can pass from the compressor and through the plurality of longitudinal channels 910 in direction B. A coolant fluid stream, such as a cool water stream, may pass through the plurality of spiral channels 920 in direction A. Fluid in the spiral channels 920 is therefore configured to flow in a direction perpendicular to the flow direction of the fluid in the plurality of longitudinal channels 910. As illustrated in Figure 9B, a plurality of stacked layers are provided. In this way, the spiral component 900 comprises a multi-layered cooling system is provided. Each layer of the plurality of stacked layers comprises a longitudinal channel 910 or a spiral channel 920. As illustrated in Figure 9B, each spiral channel 920 is sandwiched between two longitudinal channels 910, such that adjacent layers of the plurality of stacked layers comprise alternate types of channel. It is envisaged that the cross-sectional area of each stacked layer may be alternative shape to suit the shape of the component to be housed within the central aperture 930. The spiral component 900 comprises an innermost layer 910a located closest to the central axis C and, in this embodiment, comprises a longitudinal channel 910. Heat from the components of the high-speed machine located within the central aperture 903 is first transferred to the fluid stream within the innermost layer 910a before being cooled by the heat exchange effects of the subsequent layers of the plurality of stacked layers. The plurality of stacked layers allows heat from the coolant fluid stream within the spiral channels 920 is easily transferred to the hot compressed fluid stream within the adjacent longitudinal channels 910, allowing the coolant fluid to remove the excess heat from the compressed fluid stream. The cooling system is configured to encase at least a portion of the shaft assembly of the high-speed machine, which may comprise a stator, within the central aperture 930. In this way, the cooling system can be wrapped circumferentially around portions of the shaft assembly. In the embodiment of Figure 9, the cooling system can be arranged, for example, such that flow direction B of the longitudinal channels 910 is parallel to the shaft of the compressor. The cooling system allows more efficient heat exchange between the fluids in the longitudinal channels 910 and spiral channels 920 to occur, leading to improved heat exchanger efficiency, with reduced size and volume requirements than traditional external charge-air coolers which often employ bulky Fin Tube Heat Exchangers. As such, there is a reduction in the quantity of coolant fluid required. It is envisaged that a split-flow configuration may be provided wherein the spiral component 900 may comprise a plurality of distinct stand-alone or self-contained parts, each part comprising at least one spiral channel and at least one longitudinal channel. In this way, the flow of fluid through the channels is not continuous and so multiple fluid entry and exit points are present in the spiral component 900. Alternatively to the embodiment described above, the spiral channels 920 can be configured to receive a fluid stream exiting a compressor and the longitudinal channels 910 can be configured to receive a flow of coolant fluid. The abovementioned advantages also apply to this alternative configuration. However, it is preferred that the fluid stream exiting a compressor is passed through the shorter path length of the longitudinal channels 910. Figure 10A illustrates an alternative configuration of the cooling system, wherein a cylindrical component 100 is employed instead of, or in addition to, the spiral component 900 of Figure 9. The cylindrical component 1000 of Figure 10 comprises a plurality of first longitudinal channels 1010, a plurality of second longitudinal channels 1020, and a central aperture 1030 extending along a central axis C’ of the cylindrical component 1000. The cylindrical component 1000 of Figure 10 is substantially identical to the embodiment of Figure 9, but differs in that the plurality of spiral channels 920 are replaced by a plurality of second longitudinal channels 1020. In this way, no spiral channel is present and so the cylindrical component 1000 is substantially cylindrical in shape. Both the plurality of first longitudinal channels 1010 and plurality of second longitudinal channels 1020 project in a direction parallel to the central axis C’. In this way, fluid passing through the first longitudinal channels 1010 in direction B’ is travelling in the opposite direction to direction A’ of the fluid passing through the second longitudinal channels 1020. As such, the plurality of stacked layers formed by the channels in the cylindrical component 1000 form concentric layers or rings about the central axis C’, as illustrated in Figure 10B. The cooling system comprises at least one spiral component 900 and / or at least one cylindrical component 1000. In this way, the cooling system is configured to wrap around the components of the high-speed machine, such as the shaft assembly, to provide an improved cooling system. Further arrangements of stacked layers are envisaged beyond that depicted in Figures 9 and 10. For example, a stack of two, three, four, five or more layers may be provided, depending on the application of the high-speed machine. Further embodiments may comprise arrangements where the spiral channels and longitudinal channels (or the first longitudinal 5 channels and second longitudinal channels) are interspersed together, such as intertwined together. Further embodiments within the scope of the present invention may be envisaged that have not been described above, for example, there may be a different arrangement of the components of the high-speed machine than pictured. The turbine exhaust air may be configured to pass through the cooling system. Additionally, the high-speed machine may 10 comprise; two turbochargers; two compressors and one turbine provided on a single electrified shaft; or one compressor and two turbines on a single shaft. The invention is not limited to the specific examples or structures illustrated, a greater number of components than are illustrated in the Figures could be used, for example.

Claims

1. A high-speed machine, the high-speed machine comprising;a compressor comprising a shaft assembly;a cooling system; anda housing;wherein the cooling system and the shaft assembly are located within the housing; andwherein the cooling system is configured, in use, to cool both the shaft assembly and a fluid stream exiting the compressor.

2. The high-speed machine of claim 1, wherein the high-speed machine is an electrical high-speed machine.

3. The high-speed machine of claim 2, further comprising power electronics, wherein the cooling system is configured, in use, to cool the power electronics.

4. The high-speed machine of any one preceding claim, further comprising a turbine.

5. The high-speed machine of claim 4, wherein the turbine is configured to receive a fluid stream from a power system.

6. The high-speed machine of claim 4, wherein the turbine is configured to receive a compressed fluid stream from the compressor.

7. The high-speed machine of any one preceding claim, wherein the compressor is a first compressor and the high-speed machine further comprises a second compressor.

8. The high-speed machine of any one preceding claim, wherein the cooling system comprises a spiral component.

9. The high-speed machine of claim 8, wherein the spiral component comprises at least one longitudinal channel and at least one spiral channel.

10. The high-speed machine of claim 9, wherein the at least one longitudinal channel is configured to receive a fluid stream exiting the compressor and the at least one spiral channel is configured to receive a flow of coolant fluid.

11. The high-speed machine of any one of claims 8 to 10, wherein the spiral component comprises a plurality of stacked layers.

12. The high-speed machine of claim 11, wherein each layer of the plurality of stacked layers contacts the one or more adjacent layer / s of the plurality of stacked layers.

13. The high-speed machine of any one preceding claim, wherein the cooling system comprises a cylindrical component.

14. The high-speed machine of claim 13, wherein the cylindrical component comprises at least one first longitudinal channel and at least one second longitudinal channel.

15. The high-speed machine of claim 14, wherein the at least one first longitudinal channel is configured to receive a fluid stream exiting the compressor and the at least one second longitudinal channel is configured to receive a flow of coolant fluid.

16. The high-speed machine of any one of claims 13 to 15, wherein the cylindrical component comprises a plurality of stacked layers.

17. The high-speed machine of claim 16, wherein each layer of the plurality of stacked layers contacts the one or more adjacent layer / s of the plurality of stacked layers.

18. The high-speed machine of any one of claims 8 to 17, wherein the cooling system is configured to encase a stator of the shaft assembly.

19. The high-speed machine of claim 18, wherein the at least one longitudinal channel is arranged perpendicular to the stator of the shaft assembly.

20. The high-speed machine of claim 18, wherein the at least one longitudinal is arranged parallel to the stator of the shaft assembly.21

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