WO2014077691A1

WO2014077691A1 - Turbine, heat transfer cycle comprising such a turbine, use of such a turbine and method of transferring heat

Info

Publication number: WO2014077691A1
Application number: PCT/NL2013/050825
Authority: WO
Inventors: Johannes Adrianus Antonius VIEVEEN
Original assignee: Roodenburg Duurzaam Bv
Priority date: 2012-11-16
Filing date: 2013-11-15
Publication date: 2014-05-22
Also published as: NL2009828C2; EP2920434A1

Abstract

The invention relates to a turbine device (2) comprising a turbine (1) comprising a turbine inlet (11) for receiving a refrigerant, a turbine outlet (12) for discharging the refrigerant and a flow path between the turbine inlet (11) and the turbine outlet (12), the turbine (1) further comprising a rotor (20) positioned in the flow path, the rotor (20) being arranged to rotate about an axis of rotation (RA) as a result of the refrigerant flowing through the flow path, wherein the rotor comprises a central rotor inlet (21) and at least two rotor outlets (22) at a radial outward position with respect to the rotor inlet (21), the rotor comprising at least two channels (23) spiraling outwardly with respect to the axis of rotation (RA), the at least two channels (23) connecting the rotor inlet (21) to the respective rotor outlets (22), the turbine (1) further comprising a collecting reservoir (40) positioned below the rotor (20) to receive the refrigerant from the rotor outlets (22), the turbine outlet (12) is formed by a fluid outlet (12') positioned in a lower part of the collecting reservoir (40) and a gas outlet (12'') positioned in the collecting reservoir (40) at a height in between the fluid outlet (12') and the rotor outlets (22), wherein the turbine device (2) further comprises at least one of a generator (100) connected and driven by the rotor (20), and a compressor (70), the compressor and/or generator (70) at least partially be driven the rotor (20).

Description

TURBINE, HEAT TRANSFER CYCLE COMPRISING SUCH A TURBINE, USE OF SUCH A TURBINE AND METHOD OF TRANSFERRING HEAT

TECHNICAL FIELD

The invention relates to turbine comprising a turbine inlet for receiving a refrigerant, a turbine outlet for discharging the refrigerant and a flow path between the turbine inlet and the turbine outlet, the turbine further comprising a rotor positioned in the flow path, the rotor being arranged to rotate about an axis of rotation as a result of the refrigerant flowing through the flow path. The invention further relates to turbine device comprising such a turbine, a heat transfer cycle comprising such a turbine, a method of transferring heat and the use of such a turbine.

STATE OF THE ART

Heat transfer cycles are known and widely used for many purposes, such as cooling (refrigeration cycle) of buildings and refrigerators or heating a building (heating cycle). Heat transferring cycles move heat from a cold place to a warm place for instance using mechanical work.

An example of a refrigeration heat transfer cycle is a vapor-compression cycle, which comprises a compressor, a condenser, an expansion valve and an evaporator positioned in a loop through which a heat transfer fluid is pumped around. In such a cycle the heat transfer fluid is condensed and evaporated.

The heat transfer fluid is usually referred to as a refrigerant. An example of a refrigerant is Freon. In this text, the term refrigerant is used to refer to a heat transfer fluid, which may be used in refrigeration and heating cycles.

Next, a brief explanation of such a refrigeration cycle is provided.

The compressor is used to compress the gaseous refrigerant to a superheated vapor with a high pressure and high temperature.

The superheated vapor then enters the condenser where it condenses at substantially the same pressure, becomes a sub-cooled liquid and thereby loses energy, for instance to the outside or to a central heating system. Next, the sub-cooled liquid refrigerant flows through the expansion valve, thereby expanding the refrigerant causing the pressure to drop abruptly. The evaporation temperature will drop as a result of this and the liquid refrigerant will be cooled instantly by partial evaporation of the refrigerant. The refrigerant is then forwarded to the evaporator where it absorbs heat from the place to be cooled. Next, the refrigerant is fed to the compressor.

A vapor is a gaseous refrigerant with a temperature below its critical temperature. This means that the vapor can be condensed to a liquid by increasing its pressure without reducing the temperature. If the temperature of the vapor is higher than the boiling temperature of the liquid phase at a certain pressure, the vapor will be a superheated vapor. A gas having a temperature above the critical temperature cannot be condensed to a liquid by increasing the pressure.

Also known is to replace the expansion valve by a work-extracting device such as a turbine.

SHORT DESCRIPTION

It is an object of the invention to provide an improved turbine which can in particular be used in vapor-compression cycles.

According to an aspect there is provided a turbine comprising a turbine inlet for receiving a refrigerant, a turbine outlet for discharging the refrigerant and a flow path between the turbine inlet and the turbine outlet, the turbine further comprising a rotor positioned in the flow path, the rotor being arranged to rotate about an axis of rotation as a result of the refrigerant flowing through the flow path, wherein the rotor comprises a central rotor inlet and at least two rotor outlets at a radial outward position with respect to the rotor inlet, the rotor comprising at least two channels spiraling outwardly with respect to the axis of rotation, the at least two channels connecting the rotor inlet to the respective rotor outlets.

The terms spiral and spiraling refer to a curve which revolves and diverges from a central position, getting farther away from the central position as it revolves around the central position. The curve may lie within a plane, the plane being substantially perpendicular to the axis of rotation of the rotor.

The at least two channels spiraling outwardly are interwound.

By providing at least two channels with corresponding outlets, preferably uniformly distributed along the periphery of the rotor, the rotor will be stable, as the reaction forces of the escaping refrigerant are evenly distributed along the perimeter of the rotor. A pressure difference will occur between the rotor inlet and the rotor outlet as a result of the cooling process. The refrigerant will expand and will set the rotor in motion. In use, the rotor is coupled via a shaft to a generator or compressor to use the rotational energy of the rotor in a useful manner. The generator may be formed as part of the turbine.

In use, the pressure of the refrigerant will drop flowing through the rotor, reducing the vapor pressure, causing the refrigerant to evaporate partially and cooling the liquid refrigerant. As a result of the evaporation, the volume per mass of the refrigerant will increase substantially causing a substantial increase of the velocity of the refrigerant inside the channel and consequently, causing a further increase of the torque or rotational velocity of the rotor.

The refrigerant may be any suitable heat transfer fluid such as Freon.

It is noted that the turbine, when used in a refrigerant cycle, will also function as an economizer. This is in particular advantageous in order to increase the COP (coefficient of performance).

According to an embodiment the rotor is formed by two parallel rotor plates extending in a direction perpendicular to the axis of rotation with the at least two channels being formed in between the two parallel rotor plates.

The channels may for instance be formed by grooves created in one of the plates in the side facing the other plate or in both of the plates in the sides facing each other. Creation of a groove may be done by milling. The channels may also be formed by a spiraling wall positioned in between the two rotor plates.

The rotor plates may be formed as discs. The at least two walls are interwound to form an equal number of interwound channels.

According to an embodiment the rotor comprises at least three channels spiraling outwardly with respect to the axis of rotation.

By providing three channels with three corresponding rotor outlets, the rotor will be even more stable. The three or more channels are interwound. More channels and corresponding rotor outlets will make the rotor even more stable. So, the rotor may comprise four, five, six or even more channels.

According to an embodiment the turbine comprises a stator ring positioned surrounding the rotor along the periphery of the rotor, the stator ring comprising a plurality of inwardly protruding plates. In between the rotor and the stator ring there is an annular gap allowing the refrigerant to pass. The refrigerant exiting the rotor outlets at a relatively high speed in a direction tangential with respect to the rotor, will hit the inwardly protruding plates causing an additional driving force for the rotor.

According to an embodiment the plates protrude inwardly in a radial direction with respect to the stator ring.

In other words, the plates are parallel to the axis of rotation and the normal direction of the plates is tangential with respect to the stator ring.

According to an embodiment the plurality of inwardly protruding plates deflect the refrigerant exiting the rotor outlets in a direction parallel to the axis of rotation.

The inwardly protruding plates may be straight plates orientated at an angle with respect to the axis of rotation or may be curved such that the refrigerant exiting the rotor outlets is deflected in direction parallel to the axis of rotation. In case the axis of rotation is vertical, the plates are arranged to deflect the refrigerant in a downward direction. In case the axis of rotation is horizontal, the plates are arranged to deflect the refrigerant in a horizontal direction, away from the rotor. Curved plates bend the refrigerant in a smooth manner.

According to an embodiment, the turbine comprises a collecting reservoir positioned below the rotor to receive the refrigerant from the rotor outlets, the turbine outlet comprising a fluid outlet positioned in a lower part of the collecting reservoir and a gas outlet positioned in the collecting reservoir at a height in between the fluid outlet and the rotor outlets.

The rotor may be positioned such that the axis of rotation is vertically orientated. This ensures that the rotor rotates in a vapor environment (saturated vapor) and is not flooded. The liquid refrigerant will gather in the lower part of the collecting reservoir and the gaseous refrigerant will gather above the liquid refrigerant. The gas outlet also functions as an overflow ensuring that the pressure doesn't increase too much and the rotor continues to rotate. Also, the gas outlet ensures that the rotor will not flood.

A top edge of the collecting reservoir may be connected along an upper edge to the stator ring in a fluid tight manner. The stator ring and the collecting reservoir may also be formed integrally.

Alternatively, the axis of rotation may be orientated horizontally, where the collecting reservoir is positioned below the rotor. In that case, the stator ring, positioned surrounding the rotor along the periphery of the rotor, may comprise a plurality of inwardly protruding plates, the plates being provided to deflect the fluid exiting the rotor outlets towards a horizontal direction allowing the fluid to reach the collecting reservoir without being hindered by the rotor.

According to an embodiment the gas outlet comprises a conduit which protrudes into the collecting reservoir.

The conduit protrudes radial inwardly with respect to a peripheral outer wall of the collecting reservoir.

This prevents liquid refrigerant entering the gas outlet, because as a result of the rotational movement the liquid refrigerant exiting the rotor outlets will be forced in a radial outward direction with respect to the gaseous refrigerant exiting the rotor outlets. The liquid refrigerant will thus substantially flow downwards along the outer wall of the collecting reservoir and cannot enter the inwardly protruding conduit of the gas outlet.

According to an embodiment the turbine comprises a fluid-gas separator comprising an inlet, which is connected to the gas outlet of the collecting reservoir.

This is advantageous as fluid that might exit the turbine via the gas outlet can be separated from the gas. The fluid-gas separator comprises an inlet connected to the gas outlet of the turbine and a fluid outlet which may be joined with the fluid outlet of the collecting reservoir. The fluid-gas separator further comprises a gas outlet.

According to an embodiment a by-pass conduit is provided connecting the turbine inlet to the turbine outlet by-passing the rotor, the by-pass conduit comprising valve, such as a minimum pressure maintenance valve.

This is in particular advantageous when the turbine is used in a vapor- compression heat transfer cycle, as it enables the cycle to start-up.

According to an aspect there is provided a turbine device comprising a turbine according to the above, wherein the turbine device further comprises at least one of

- a generator connected and driven by the rotor, and

- a compressor, the compressor at least partially be driven the rotor.

The generator may be any suitable type of generator which can be driven by the rotor. The generator may be connected and driven by the rotor by means of a rotational shaft. The rotational shaft is driven by the rotor of the turbine. The rotational shaft may be connected to a compressor via a gearbox to take into account differences in rotational speed. The compressor and the turbine may be part of a heat transfer cycle, such as a refrigerant cycle. This embodiment provides an energy- efficient turbine device.

According to an embodiment the turbine device comprises a compressor and the turbine device comprises a compressor inlet and a compressor outlet.

The compressor inlet is arranged to be connected to an outlet of an evaporator and the compressor outlet is arranged to be connected to inlet of a condenser. The turbine inlet may be connected to an outlet of a condenser. The turbine outlet is arranged to be connected to an inlet of the evaporator.

The connection between the turbine outlet and the evaporator may comprise an expansion valve. The expansion valve may be provided as part of the turbine device and is provided to control the flow rate to the evaporator.

According to an embodiment the turbine comprises a collecting reservoir positioned below the rotor to receive the refrigerant from the rotor outlets, the turbine outlet is formed by a fluid outlet positioned in a lower part of the collecting reservoir and a gas outlet positioned in the collecting reservoir at a height in between the fluid outlet and the rotor outlets,

wherein the turbine comprises a fluid-gas separator connected to the gas outlet, the fluid-gas separator comprising an inlet connected to the gas outlet of the turbine, wherein the fluid-gas separator comprises a gas outlet, which is connected to the compressor.

The gas outlet of the fluid-gas separator may be connected to the compressor inlet described above or may be connected to a secondary gas inlet of the compressor.

According to an embodiment the gas-fluid separator further comprises a fluid outlet which is connected to the fluid outlet positioned in the lower part of the collecting reservoir.

According to an aspect there is provided a heat transfer cycle, comprising a turbine according to the above.

The heat transfer cycle may be a refrigerant cycle or a heating cycle.

According to an embodiment the heat transfer cycle further comprises a compressor, a condenser and an evaporator. The heat transfer cycle may further comprise an expansion valve positioned in between the turbine and the evaporator. The heat transfer cycle preferably is a vapor-compression cycle known to the skilled person.

According to an embodiment the refrigerant cycle further comprises a by-pass conduit by-passing the turbine, the by-pass conduit comprising a valve , such as a minimum pressure maintenance valve.

The function of the by-pass conduit is to facilitate start-up of the cycle in case less pressure difference is available between the condenser and the evaporator and a relatively high resistance of the (non-moving) turbine and expansion valve. This is important to ensure that the liquid/vapor, entering the evaporator, exits the evaporator as pure vapor which is somewhat overheated.

According to an aspect there is provided a method of transferring heat comprising a) compressing a refrigerant from a gaseous state to a superheated vapor using a compressor,

b) condensing the superheated vapor to a sub-cooled liquid using a condenser whereby the refrigerant looses heat to a temperature sink,

c) expanding the sub-cooled liquid to a liquid- vapor mixture, and

d) evaporating the liquid part of the liquid- vapor mixture into the gaseous state using an evaporator whereby the refrigerant takes up heat from a temperature source,

wherein action c) is performed by guiding the refrigerant through at least two outwardly spiraling channels formed in a rotor, thereby rotating the rotor about an axis of rotation.

Actions a) - d) are performed in a continuous loop or cycle. The vapor part of the liquid-vapor mixture in action c) and the gaseous state formed in action d) are provided to the compressor in action a).

In fact, action c) can be performed by any one of the turbines described above.

According to an embodiment energy is derived from the rotation of the rotor.

According to an embodiment energy from the rotation of the rotor is used to at least partially drive the compressor.

According to an embodiment action c) comprises separating the liquid part and the vapor part from the liquid- vapor mixture using a collecting reservoir positioned below the rotor to receive the refrigerant from the rotor outlets.

The method may comprise obtaining a liquid part of the liquid-vapor mixture from a liquid outlet positioned in a lower part of the collecting reservoir and obtaining a mainly gaseous part of the liquid-vapor mixture from a gas outlet positioned in the collecting reservoir at a height in between the fluid outlet and the rotor outlets.

The method may further comprise providing the gaseous part of the liquid-vapor mixture obtained via the gas outlet to a fluid-gas separator connected to the gas outlet. Further the method may comprise obtaining a gas from a gas outlet of the fluid-gas separator and provide it to a compressor. Further the method may comprise obtaining a liquid from a liquid outlet of the fluid-gas separator and join it with the liquid outlet of the colleting reservoir.

An aspect relates to the use of a turbine according to the above, wherein a high- pressure and high temperature liquid refrigerant is provided to the turbine inlet and a low pressure and low temperature liquid-vapor refrigerant is obtained from the turbine outlet.

The terms high and low pressure are used in relation to each other, i.e. to indicate that the pressure at the turbine inlet is higher than the pressure at the turbine outlet. The terms high and low temperature are used in relation to each other, i.e. to indicate that the temperature at the turbine inlet is higher than the temperature at the turbine outlet.

SHORT DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

Figure 1 to 3 schematically depict heat transferring schemes according to different embodiments,

Figure 4 shows a pressure-enthalpy diagram of a cooling cycle obtainable with the heat transferring schemes of figs. 1-3

Figures 5a - 5e schematically depict a turbine according to an embodiment for use in the turbine device according to the invention.

DETAILED DESCRIPTION

Figs. 1-3 schematically depict a heat transfer cycle according to several embodiments. The heat transfer cycle comprises a loop comprising an evaporator 90, a compressor 70, a condenser 80 and an expander, embodied as a turbine 1. As shown in Figs. 1-3, the turbine is part of a turbine device 2 (dashed square). The evaporator 90 is in thermal contact with a temperature source 5 and the condenser 80 is in thermal contact with a temperature sink 6. A heat transfer fluid, usually referred to as a refrigerant, is pumped through the cycle from the compressor 70 to the condenser 80 to the turbine 1 to the evaporator 90 back to the compressor 70.

The compressor 70 comprises a compressor outlet 72 which is in fluid

communication with an inlet 81 of the condenser. The condenser 80 comprises an outlet 82 which is in fluid communication with a turbine inlet 11 of the turbine. The turbine 1 comprises a turbine outlet 12 which is in fluid communication with an inlet 91 of the evaporator 90. The evaporator 90 comprises an outlet 92 which is in fluid communication with a compressor inlet 71.

The turbine 1 comprises a turbine inlet 11 and a turbine outlet 12 in between which a rotor 20 is positioned. The rotor is positioned in a housing 28. The housing 28 comprises an opening to receive refrigerant from the outlet 82 of the condenser 80.

Figs. 2-3 schematically depict a heat transfer cycle according to another embodiment. The cycle further comprises an expansion valve 13, which may be part of a turbine device 2 or may be provided separately.

The evaporator 90 is in thermal contact with a temperature source 5 and the condenser 80 is in thermal contact with a temperature sink 6. A heat transfer fluid, usually referred to as a refrigerant, is pumped through the cycle from the compressor 70 to the condenser 80 to the turbine 1 to the evaporator 90 back to the compressor 70.

The compressor 70 comprises a compressor outlet 72 which is in fluid

communication with an inlet 81 of the condenser. The condenser 80 comprises an outlet 82 which is in fluid communication with a turbine inlet 11 of the turbine. The turbine 1 comprises a turbine outlet 12 which is in fluid communication with an inlet 91 of the evaporator 90. The connection between the turbine 1 and the evaporator 90 comprises the expansion valve 13. The evaporator 90 comprises an outlet 92 which is in fluid communication with a compressor inlet 71.

Figure 4 shows a pressure-enthalpy diagram of a cooling cycle obtainable with the heat transferring schemes described above. The vertical axis represents the pressure of the system on a logarithmic scale, the horizontal axis represents the enthalpy of the system. The superheated vapor entering the compressor suction would be at point A in Fig. 4. The superheated vaporized refrigerant is compressed from a gaseous state to a superheated vapor using a compressor, following the line to the pressure corresponding to the condensing temperature (point B). The refrigerant vapor experiences a sensible heat gain during the mechanical compression process, resulting in an even more superheated vapor. This is illustrated by the location of points A and B, to the right of the saturated vapor line. Point B represents the outlet of the compressor/inlet of the condenser. The condenser serves as a two-fold component. Before any condensation occurs, the high pressure vapor must first be brought to a saturated condition (de- superheated). Enough heat must be transferred from the refrigerant to lower its temperature from the superheated temperature to the saturation temperature of point B' in the diagram. At this point, condensation of the superheated vapor to a sub-cooled liquid using a condenser whereby the refrigerant looses heat to a temperature sink can begin. As heat continues to be transferred from the refrigerant vapor to the air (or any other appropriate fluid to be cooled), the quality of the refrigerant (% of the refrigerant in the vapor state) will continue to decrease, until the refrigerant has been completely condensed and potentially sub-cooled. This occurs at the outlet of the condenser (point C). Next the sub-cooled liquid refrigerant is expanded to a liquid-vapor mixture in the turbine 1 described above, to reach point D in the diagram, by guiding the refrigerant through at least two outwardly spiraling channels formed in the rotor, thereby rotating the rotor about an axis of rotation. Point E in the diagram represents the state of the liquid-vapor refrigerant mixture for a heat cycle without a turbine for expansion of the liquid refrigerant. The difference between point E and D represents the enthalpy gain, i.e. energy gain, when using a turbine. Under influence of the forces generated by the expansion of the liquid refrigerant in the spiraling channels of the rotor, the rotor will start to rotate. This movement of the rotor extracts energy from the refrigerant, i.e. lowers the enthalpy of the vapor and the liquid, such that the temperature and the pressure of the liquid and the vapor drops, forming a liquid and vapor, and less liquid will evaporate within the rotor. As the enthalpy of the liquid has decreased, more energy can be extracted from the surroundings with the same amount of liquid in the evaporator.

Subcooling or superheat cannot exist where there is a mixture of liquid and vapor refrigerant. Therefore, any place in the system where the refrigerant exists in two states (the receiver, parts of the evaporator and condenser, the accumulator at times), it will be at the saturation temperature for its pressure. Some of the liquid refrigerant is required to boil as a means of removing the heat necessary to achieve this lower temperature.

The final portion of the heat cycle comprises a mixture of liquid and vapor refrigerant, traveling though the evaporator. Air, water, oil and/or any other fluid to be cooled, flows across the evaporator, where its heat content is transferred to the boiling refrigerant. This is a latent heat gain to the refrigerant, causing no temperature increase, while experiencing a change of state. Ideally, the liquid is has completely evaporated at the evaporator outlet, which is connected to the compressor inlet. Hence, at the inlet of the compressor vapor is present, preferably superheated vapor. The cycle continues this way until the refrigerated space temperature is satisfied, and the equipment cycles off.

The vapor part of the liquid- vapor mixture at point D and the gaseous state formed at point A are provided to the compressor to become liquid refrigerant at point B.

The rotor 20 is shown in more detail in Fig.'s 5a - 5e. The rotor 20 is formed by two parallel plates 24 in between which two or more interwound channels 23 are formed which spiral around a central axis of rotation RA, the axis of rotation RA being substantially perpendicular to the surface of the parallel plates 24. The channels 23 may be formed by walls 25 positioned in between the plates 24. However, the channels 23 may also be formed as grooves in one or both of the plates 24.

The rotor 20 comprises a hollow pipe 26 which protrudes from one of the plates 24 in a direction along the rotational axis RA. The hollow pipe 26 comprises one or more openings 27 to allow fluid into the hollow pipe 26. The openings 27 may optionally have a tangential component to take into account the rotational direction of the rotor when in use. This can best be seen in Fig. 5b. Alternatively, the hollow pipe 26 comprises a stepwise narrowing in a direction away from the rotor 20, thereby creating a surface with a normal parallel to the rotational axis RA in which openings 27 may be provided.

The hollow pipe 26 further comprises openings in between the two plates 24 forming rotor inlets 21. Again, these openings 21 may have a tangential component to take into account the rotational direction of the rotor 20 when in use. Fig. 5a shows a more detailed cross-sectional view of the turbine 1 as part of a turbine device 2 according to an embodiment.

The turbine 1 may further optionally comprise a stator ring 30 surrounding the rotor 20 along the periphery of the rotor 20. The stator ring 30 comprises a plurality of inwardly protruding plates 31. The plates 31 may protrude radially inwardly, but may also be orientated or curved to divert the refrigerant exiting the channels 23 via the rotor outlets 22 towards a collecting reservoir 40 positioned underneath the rotor 20.

In an alternative embodiment (not shown) in which the axis of rotation RA is horizontally, the plates may be orientated or curved to divert the refrigerant exiting the channels 23 via the rotor outlets 22 to a horizontal direction towards a collecting reservoir 40 positioned underneath the rotor 20.

It is noted that the stator ring 30 and/or the collecting reservoir 40 may be integrally formed with the housing 28.

Bearings 29 are provided to allow the rotor 20 to rotate inside the housing 28. Mechanical seals are also provided as a separation between the liquid phase entering the turbine 1 (present upstream of the openings 27) and the liquid- vapor mixture present downstream of the rotor. Fig. 1 (and 2 and 3) show a different position and design of the housing 28, bearings 29 and the rotor 20 than Fig. 5a. In Fig. 1 (and 2 and 3) the bearings 29 are provided in between the hollow pipe 26 and the housing 28. In the embodiment shown in Fig. 5a the bearings 29 are provided in between the upper plate 24 and the housing 28.

Fig.'s 5a - 5e sow the turbine 1 in more detail. Fig. 5a shows a cross-sectional view of the turbine 1 positioned inside the housing 28 in a different embodiment than Fig. 1, 2 and 3.

Fig. 5b shows the turbine 1 in a disassembled state, clearly showing the hollow pipe 26, the openings 27, the rotor inlet 21 and the interwound spiraling channels 23. Fig. 5c shows the top plate 24 and the hollow pipe 26 in more detail. Fig. 5d shows a view of the turbine without the lower plate 24, now clearly showing the stator 30 and the inwardly protruding plates 31, in this case positioned at an angle with respect to the rotational axis RA to deflect the refrigerant in a direction towards the collecting reservoir 40. The angle may be in the range of 25° - 60°. Finally, Fig. 5e shows a top view of the plurality of interwound outwardly spiraling channels 23. Figs. 1-3 show the collecting reservoir 40 comprising a fluid outlet 12' in the bottom of the collecting reservoir 40 and a gas outlet 12" positioned at a level in between the rotor 20 and the fluid outlet 12'. The gas outlet 12" comprises a conduit 41 protruding inwardly to prevent fluid from exiting the collecting reservoir via the conduit 41.

The turbine device 2 may further comprise a fluid-gas separator 50 and a by-pas conduit 60. The fluid-gas separator 50 and/or the by-pass conduit 60 may also be provided separate from the turbine device 2.

The gas outlet 12" may be connected to an inlet 51 of the fluid-gas separator 50. The fluid-gas separator 50 may be a reservoir with a fluid outlet 52. The fluid outlet 52 is connected to the fluid outlet 12' of the collecting reservoir 40. The fluid-gas separator 50 comprises a gas outlet 53, which may be connected to the compressor 70.

The by-pass conduit 60 connects the turbine inlet 11 to the turbine outlet 12 bypassing the turbine 1 or at least the rotor 20. The by-pass conduit 60 connects the turbine inlet 11 directly to the expansion valve 13. The by-pass conduit 60 comprises a valve 61 to maintain a minimum pressure for the expansion valve 13

The rotor 20 is arranged to drive a generator 100 as shown in Figs. 1 and 2. This may for instance be established by mechanically coupling the hollow pipe 26 to a drive shaft of the generator 100. The coupling may comprise a gearbox.

Fig. 3 shows an alternative embodiment in which the turbine device 2 also comprises the compressor 70 and the rotor 20 is arranged to drive the compressor 70. This may be established by mechanically coupling the hollow pipe 26 to a drive shaft of the compressor 70. The coupling may comprise a gearbox.

In use, a refrigerant is circulated through the heat transfer cycle as described above, including the turbine device 2 comprising the turbine 1. In order to start up the cycle, the refrigerant may travel through the by-pass conduit 60, but once started up, the refrigerant is guided through the interwound outwardly spiraling channels 23 thereby allowing the fluid to expand and thus causing the rotor 20 to rotate around the axis of rotation RA. In the rotor, the refrigerant will partially become gaseous, so a liquid-vapor mixture exits the rotor outlets 22 and is collected and separated in the collecting reservoir 40. Liquid will gather in the lower part of the collecting reservoir 40 where it leaves the collecting reservoir 40 via liquid outlet 12' . The vapor leaves the collecting reservoir 40 via gas outlet 12" where it is further separated by gas-liquid separator 53. The gas-liquid separator 53 is not necessary when at the gas outlet 12" only gas is present, e.g. when the liquid level in the reservoir 40 does not reach the gas outlet 12", as shown in fig. 1

The gas outlet 53 of the fluid-gas separator 50 may be connected to the compressor inlet 71 described above or may be connected to a secondary gas inlet 7 of the compressor.

In use, the rotor 20 will be driven thereby collecting energy from the refrigerant that would otherwise be lost. This energy can be used to at least partially drive a generator 100 (see Figs. 1 and 2) or the compressor 70 (see Fig. 3).

The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

Claims

1. Turbine device (2) comprising

- a turbine (1) comprising a turbine inlet (11) for receiving a refrigerant, a turbine outlet (12) for discharging the refrigerant and a flow path between the turbine inlet (11) and the turbine outlet (12), the turbine (1) further comprising a rotor (20) positioned in the flow path, the rotor (20) being arranged to rotate about an axis of rotation (RA) as a result of the refrigerant flowing through the flow path, wherein the rotor comprises a central rotor inlet (21) and at least two rotor outlets (22) at a radial outward position with respect to the rotor inlet (21), the rotor comprising at least two channels (23) spiraling outwardly with respect to the axis of rotation (RA), the at least two channels (23) connecting the rotor inlet (21) to the respective rotor outlets (22), the turbine (1) further comprising a collecting reservoir (40) positioned below the rotor (20) to receive the refrigerant from the rotor outlets (22), the turbine outlet (12) is formed by a fluid outlet (12') positioned in a lower part of the collecting reservoir (40) and a gas outlet (12") positioned in the collecting reservoir (40) at a height in between the fluid outlet (12') and the rotor outlets (22),

wherein the turbine device (2) further comprises at least one of a generator (100) connected and driven by the rotor (20), and a compressor (70), the compressor (70) and/or the generator at least partially be driven the rotor (20).

2. Turbine device (2) according to claim 1, wherein the turbine (1) comprises a fluid-gas separator (50) connected to the gas outlet (12"), the fluid-gas separator (50) comprising an inlet (51) connected to the gas outlet (12") of the turbine (1), wherein the fluid-gas separator (50) comprises a gas outlet (53), which is connected to the compressor (70).

3. Turbine device (2) according to claim 1 or 2, wherein the rotor (20) is formed by two parallel rotor plates (24) extending in a direction perpendicular to the axis of rotation with the at least two channels being formed in between the two parallel rotor plates (24).

4. Turbine device (2) according to any one of the preceding claims, wherein the rotor (20) comprises at least three channels (23) spiraling outwardly with respect to the axis of rotation (RA).

5. Turbine device (2) according to any one of the preceding claims, wherein the turbine (1) comprises a stator ring (30) positioned surrounding the rotor (20) along the periphery of the rotor (20), the stator ring comprising a plurality of inwardly protruding plates (31).

6. Turbine device (2) according to claim 5, wherein the plates (31) protrude inwardly in a radial direction with respect to the stator ring (30).

7. Turbine device (2) according to claim 5, wherein the plurality of inwardly protruding plates (31) deflect the refrigerant exiting the rotor outlets in a direction parallel to the axis of rotation.

8. Turbine device (2) according to any one of the preceding claims, wherein, the turbine (1) comprising a collecting reservoir (40) positioned below the rotor (20) to receive the refrigerant from the rotor outlets (22), the turbine outlet (12) comprising a fluid outlet (12') positioned in a lower part of the collecting reservoir (40) and a gas outlet (12") positioned in the collecting reservoir (40) at a height in between the fluid outlet (12) and the rotor outlets (22).

9. Turbine device (2) according to claim 8, wherein the gas outlet (12") comprises a conduit (41) which protrudes into the collecting reservoir (40).

10. Turbine device (2) according to any one of the preceding claims, wherein the turbine (1) comprises a fluid-gas separator (50) comprising an inlet (51), which is connected to the gas outlet (12") of the collecting reservoir (40).

11. Turbine device (2) according to any one of the preceding claims, wherein a bypass conduit (60) is provided connecting the turbine inlet (11) to the turbine outlet (12) by-passing the rotor (22), the by-pass conduit (60) comprising a valve (61).

12. Turbine device (2) device according to claim 11, wherein the turbine device (2) comprises a compressor (70) and the turbine device (2) comprises a compressor inlet (71) and a compressor outlet (72).

13. Turbine device (2) according to any of the preceding claims, wherein the gas- fluid separator (50) further comprises a fluid outlet (52) which is connected to the fluid outlet (12') positioned in the lower part of the collecting reservoir (40).

14. Heat transfer cycle, comprising a turbine device (2) according to any one of the preceding claims.

15. Heat transfer cycle according to claim 14, wherein the heat transfer cycle further comprises a compressor (70), a condenser (80) and an evaporator (90).

16. Heat transfer cycle according to claim 15, wherein the heat transfer cycle further comprises a by-pass conduit (60) by-passing the turbine (1), the by-pass conduit (60) comprising an expansion valve (61).

17. Method of transferring heat comprising

a) compressing a refrigerant from a gaseous state to a superheated vapor using a compressor (70),

b) condensing the superheated vapor to a sub-cooled liquid using a condenser (80) whereby the refrigerant looses heat to a temperature sink (6),

c) expanding the sub-cooled liquid to a liquid- vapor mixture, and

d) evaporating the liquid part of the liquid- vapor mixture into the gaseous state using an evaporator (90) whereby the refrigerant takes up heat from a temperature source (5), wherein action c) is performed by guiding the refrigerant through at least two outwardly spiraling channels formed in a rotor (20), thereby rotating the rotor (20) about an axis of rotation (RA).

18. Method according to claim 17, wherein energy is derived from the rotation of the rotor (20).

19. Method according to claim 18, wherein energy from the rotation of the rotor (20) is used to at least partially drive the compressor (70).

20. Method according to any one of the claims 17 - 19, wherein action c) comprises separating the liquid part and the vapor part from the liquid-vapor mixture using a collecting reservoir (40) positioned below the rotor (20) to receive the refrigerant from the rotor outlets (22).

21. Use of a turbine device (2) according to any one of the claims 1 - 13, wherein a high-pressure and high temperature liquid refrigerant is provided to the turbine inlet (11) and a low pressure and low temperature liquid-vapor refrigerant is obtained from the turbine outlet (12).