Heat transfer system

Abstract

A heat transfer system and methods for exchanging heat between a working fluid and a heat transfer fluid are provided. The system comprises a rotor assembly arranged around a rotational axis. The rotor assembly comprises a rotary compressor configured to compress the working fluid. A rotary heat exchanger of the rotor assembly exchanging heat between the working fluid and the heat transfer fluid. An expansion system of the rotor assembly is configured to reduce a pressure of the working fluid such that the working fluid expands into to a multi-phase mixture.

Description

HEAT TRANSFER SYSTEMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 566,957, filed March 19, 2024. The above-referenced patent application is incorporated by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] The present disclosure relates to heat transfer systems such as heat pumps, and to methods of transferring heat.BACKGROUND

[0003] Heat transfer systems are employed across industrial applications to transfer heat from a heat source to a heat sink (e.g., a component or system to which heat is provided). Heat transfer systems typically involve heating a working fluid by the heat source, transferring heat from the working fluid to a heat transfer fluid (HTF), and using the HTF to heat the heat sink.

[0004] Heat transfer systems, particularly at industrial scale and temperature increases (temperature lift), are typically large, requiring substantial space allocation and supporting infrastructure. These space requirements can present challenges in applications where installation footprint needs to be minimized or where there are physical constraints on system positioning and layout.

[0005] Furthermore, conventional heat transfer systems may be limited in the temperature lift they can achieve, and / or may be relatively inefficient, requiring large amounts of power to operate. Despite this, heat transfer systems such as heat pumps hold promise for reducing industrial carbon footprint. Increasing the efficiency of such systems, and thus reducing their power consumption, may further reduce the carbon footprint associated with such systems,SUMMARY

[0006] In accordance with a first aspect of the disclosure there is provided a heat transfer system which exchanges heat between a working fluid and a heat transfer fluid. A stationary heat exchanger exchanges heat between the working fluid and a heat source. A rotor assembly isarranged around a rotational axis. The rotor assembly includes a rotary compressor that is in fluid communication with the stationary heat exchanger and compresses the working fluid. A rotary heat exchanger in the rotor assembly exchanges heat between the working fluid and the heat transfer fluid, cooling the compressed working fluid. An expansion system, in fluid communication with the stationary heat exchanger, reduces the pressure of the working fluid such that it transitions to a multi-phase mixture. For example, such an expansion system may expand the working fluid into a mixture of (at least) vapor and liquid.

[0007] As a rotary -based system, such a heat transfer system uses centrifugally induced hydrostatic force to achieve compression of the working fluid, which may be more efficient than volume compression, such as positive displacement systems (such as pistons, scrolls, vain roller, etc), or flow based systems, using blade-based turbines (such in as axial and radial turbines), as in some conventional compressors. Further, rotary-based systems may be more space-efficient than conventional alternatives, enabling their use in more locations and applications.

[0008] Expanding into the multi-phase mixture enables the system to operate on highly efficient thermodynamic cycles. For example, the system may operate on a transcritical cycle, or a vapor compression cycle, or modifications thereof. In contrast to conventional gas cycles, where the working fluid remains in a gaseous state, these cycles may provide increased efficiency and increased power density. An increased power density means that, for a desired temperature lift, the component size and weight may be reduced compared to conventional systems. A reduced component size and weight leads to lower manufacturing costs and mechanical loads. Furthermore, such cycles allow vertical mounting of the rotor assembly, further minimizes structural loading requirements and increasing flexibility of positioning. In addition, the increased power density of these cycles may allow increased temperature lift compared to conventional systems, that is, allowing higher temperatures to be achieved at the heat sink. This may expand the number of applications for which a heat pump may be used.

[0009] The rotor assembly may include a single rotary heat exchanger. In other words, the system may comprise a single loop or single stage of the working fluid cycle. In contrast, some conventional approaches have required multiple stages to achieve desired temperature lifts. As well as adding to the size of such conventional systems, using multiple stages also reduces the overall efficiency of the system, as the inefficiencies in each stage combine.

[0010] In some examples the system may operate in a transcritical cycle. For example, in some examples, the rotary compressor may compress the working fluid from a non-critical state into a supercritical state. A supercritical state is a state above the critical point of a particular fluid, where distinct gas and liquid phases do not exist. When the working fluid is compressed to a supercritical state, the rotary heat exchanger may cool the compressed working fluid from this supercritical state, for example into a liquid state. The rotary heat exchanger may comprise a gas cooler heat exchanger. Using a transcritical cycle, particularly in a system comprising a single compression stage of the working fluid, may provide higher efficiencies than other systems, as well as higher temperature lifts. The rotary compressor of the present systems may achieve compression into the supercritical state by making use of the centrifugal force from rotation.

[0011] In some examples the system may operate in a vapor compression cycle. For example, the rotary compressor may compress the working fluid while it is in a vapor phase. The rotary heat exchanger may comprise a condenser, condensing the working fluid into a liquid, before the expansion system expands the working fluid into a mixture comprising vapor and liquid. As with the transcritical cycle, the temperature lift and efficiency of using a vapor cycle may be increased compared to conventional approaches, such as systems based on gas cycles.

[0012] In some examples, the expansion system may be configured to reduce a rotational velocity of the working fluid. For example, the expansion system may accelerate the working fluid in a direction opposite to a tangential velocity of the working fluid. As the expansion system expands the working fluid into a multi-phase mixture, the system experiences large density changes. In particular, any liquid phase component of the working after expansion has a density much greater than that of any vapor phase component. As the system is rotation, the greater density liquid may tend to be pushed outwards under centrifugal force, back towards the heat exchanger. This may create blockages in the flow of working fluid around the working fluid cycle, and limit extraction of the working fluid from the rotor assembly. However, reducing the rotational velocity of the working fluid by the expansion system may reduce this effect, facilitating removal of the working fluid from the rotor assembly, and maintaining flow of the working fluid around the working fluid cycle.

[0013] In some such examples, the expansion system may comprise a nozzle that is shaped to accelerate the working fluid in a direction opposite to the tangential velocity. The expansion system may be shaped to direct the working fluid from the rotary heat exchanger through thenozzle. Such a nozzle may provide a light-weight, space-efficient solution to reducing the rotational velocity of the working fluid. Furthermore, in accelerating the working fluid in this way, the nozzle may recover rotational energy extracted from the working fluid, which may then be passed to the rotor assembly to contribute towards rotating the rotating components, increasing efficiency of the heat transfer system.

[0014] The expansion system may include one or more channels that direct working fluid from the nozzle towards the rotational axis. The working fluid may then be extracted from the rotor assembly along or proximal to the rotational axis. These channels may be arranged to have a large tangential component of flow direction, limiting addition of rotational energy to the slowed working fluid. For example, a spiral flow path, such as an Euler flow path centered on the rotational axis, may be used. Alternatively or additionally, in some examples the expansion system (heat transfer system generally) may comprise one or more non-rotating paths for removing decelerated (with respect to the stationary frame, e.g., by a nozzle) working fluid from the rotor assembly. Such paths may receive working fluid at / from an outer radius of the rotor assembly. For example, the heat transfer system may comprise one or more stators comprising such non-rotating flow paths. Such non-rotating paths may then connect the working fluid back to the stationary heat exchanger / heat source..

[0015] In some examples, the rotary compressor may include a compression heat exchanger that transfers heat to or from the working fluid as the working fluid is compressed by the rotary compressor. For example, heat may be transferred to the heat transfer fluid, or to a secondary heat transfer fluid (e.g., in an HTF loop separate to the main HTF loop at least as it passes through the rotor assembly). Any such secondary HTF may be combined with the main HTF to combine the transferred heat.

[0016] Such a compression heat exchanger may allow for modification of the thermal cycle on which the system operates to be modified. For example, the thermal cycle may be tailored to achieve particular characteristics given the desired temperature lift at the heat sink. For example, removing heat from the working fluid during compression may allow the system to operate on modified versions of the transcritical or vapor cycles.

[0017] The extraction of heat during compression through the compression heat exchanger may allow higher compression ratios to be achieved. The working fluid can reach increased densities compared to systems without compression heat exchange. These higher densities enhancethe performance characteristics associated with denser working fluids. Further, the removal of heat during compression increases the density of the working fluid, allowing the same compression pressure to be achieved at lower rotational speeds. Lower motor RPM requirements result in reduced power consumption for compression. The combination of increased heat transfer to the sink fluid and reduced compression power leads to lower operating energy requirements.

[0018] The rotary compressor may be shaped such that a cross-sectional area of a flow path of the working fluid through the rotary compressor decreases as radial position away from the rotational axis increases. The decreasing cross-sectional area of the flow path through the rotary compressor accommodates changes in working fluid density during compression. As the working fluid moves radially outward under rotational forces, its density increases due to compression. A progressive reduction in flow path area may help maintain consistent flow rates and enables control over fluid velocities through the compressor.

[0019] In some examples, the working fluid may comprise one or more of: a halomethane, a hydroflueorcarbon, a hydrofluoroolefin, and / or a hydrochlorofluoroolefin. The working fluid may additionally include a noble gas and / or a refrigerant. Such fluids may be well suited to operating in thermal cycles in which the fluid enters a multi-phase mixture (also referred to herein as entering the vapor dome), particularly in a rotating system. For example, such working fluids may provide relatively high heat capacity ratio, which may be beneficial for rotary compression to ensure the work of rotational compression raises the fluid’s overall temperature rather than exciting vibrations within the fluid’s molecular structure. Such fluids may also be environmentally safe.

[0020] In some such examples, the working fluid may comprise a mixture of the high heat capacity ratio fluids listed above with a higher heat capacity fluid such as a conventional refrigerant (e.g., carbon dioxide, ammonia, water, etc.). Such a combination may maintain the temperature lift due to rotationally induced hydrostatic compression of high specific heat capacity ratio fluids while increasing the fluid power (J / kg) achievable.

[0021] Alternatively or additionally, the working fluid may comprise a mixture of the high heat capacity ratio and / or higher heat capacity fluids above with a Nobel gas (e.g., xenon, krypton, argon, etc.). Such a mixture may increase the hydrostatic pressures of the working fluid, for example inducing higher temperatures.

[0022] In accordance with a second aspect of the disclosure there is provided a method of transferring heat between a working fluid and a heat transfer fluid involves compressing theworking fluid by rotational compression. Heat is exchanged between the working fluid and the heat transfer fluid using a rotating heat exchanger. The working fluid is then expanded such that it transitions to a multi-phase mixture. Any of the examples of the first aspect discussed herein may be applied to the second aspect.

[0023] In accordance with a third aspect of the disclosure there is provided heat transfer system for exchanging heat between a working fluid and a heat transfer fluid, the heat transfer system comprising: a rotor assembly arranged around a rotational axis, the rotor assembly comprising: a rotary compressor configured to compress the working fluid; a heat exchanger for exchanging heat between the working fluid and the heat transfer fluid; and an expansion system in fluid communication with the stationary heat exchanger, the expansion system configured to reduce a pressure of the working fluid such that the working fluid expands into a multi-phase mixture. For example, the heat exchanger may comprise either or both of a rotary heat exchanger and / or a compression heat exchanger. For example, a compression heat exchanger alone (e.g., as part of a rotary compressor, as discussed above and herein) may provide the heat transfer needed for an application. Any of the examples of the first aspect discussed herein may be applied to the third aspect.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Examples of the present disclosure will now be described with reference to the accompanying drawings:

[0025] Figure 1 is a schematic diagram showing a heat transfer system for exchanging heat between a working fluid and a heat transfer fluid;

[0026] Figure 2 is a schematic diagram showing components of a rotor assembly within a heat transfer system;

[0027] Figure 3 is a schematic diagram showing a rotor assembly with a compressor heat exchanger;

[0028] Figure 4 is a perspective view showing a rotor assembly without an external housing;

[0029] Figure 5 is an exploded view showing components of an example rotor assembly;

[0030] Figure 6 is a cross-sectional view showing fluid flow paths through a rotor assembly;

[0031] Figure 7 is a plan view showing a rotary compressor configuration within a rotor assembly;

[0032] Figure 8 is a schematic diagram showing a rotary compressor with a compression heat exchanger;

[0033] Figure 9 is a schematic diagram showing fluid flow paths through a heat transfer fluid structure;

[0034] Figure 10 is a schematic diagram showing an example expansion system;

[0035] Figure 11 is an exploded view showing components of a rotary heat exchanger;

[0036] Figure 12 and Figure 13 show graphs illustrating an example transcritical cycle;

[0037] Figure 14 shows a graph of an example vapor cycle;

[0038] Figure 15 shows an example of a modified transcritical cycle;

[0039] Figure 16 shows an example of a modified vapor cycle;

[0040] Figure 17 shows example modified compression processes; and

[0041] Figure 18 is a flow diagram showing a method of transferring heat between a working fluid and a heat transfer fluid.DETAILED DESCRIPTIONHeat Transfer System Overview

[0042] Figure 1 shows a schematic diagram of an example heat transfer system 100 configured to exchange heat between a working fluid 106 and a heat transfer fluid 108. The working fluid 106 flows around a closed loop of the heat transfer system 100, transferring heat from a heat source to the heat transfer fluid 108. The heat transfer fluid 108 may be mostly or substantially incompressible and may for example comprise of water or water-glycol and can directly or indirectly provide heat energy to a thermal storage system.

[0043] The heat transfer system 100 includes a rotor assembly 102 arranged around a rotational axis 112. The rotor assembly 102 comprises components that rotate around the rotational axis 112 and may be mounted horizontally, vertically, or at an angle. A motor may drive rotation of the rotor assembly 102. The rotor assembly 102 may include a housing and a vacuum pump configured to generate at least a partial vacuum within the housing to reduce rotational friction. The housing can provide structure and protection, including containment of materials within the rotor assembly 102.

[0044] A stationary heat exchanger 104 exchanges heat between the working fluid 106 and a heat source. The heat source may for example comprise ambient air, a refrigeration system, a geothermal heat source, a waste heat stream, a wastewater stream, a power system, a combined heat and power system, a carbon capture process, a body of water, a district energy system, a solar thermal heat source, a nuclear reactor, a direct air capture system, condenser heat from a cooling system, cool thermal storage, or a cooling application, or any other heat source or combinations thereof. The stationary heat exchanger 104 may be configured to transfer heat between the working fluid 106 and a secondary heat transfer fluid loop running to / from the heat source. Alternatively, the working fluid 106 may run directly to the heat source. The stationary heat exchanger 104 remains stationary and does not rotate with the rotor assembly 102. The stationary heat exchanger 104 may have the form of any conventional heat exchanger. In some examples the stationary heat exchanger 104 may be or comprise an evaporator, for example configured to cause evaporation of the working fluid 106 as it passes through the stationary heat exchanger 104.

[0045] As illustrated, the system 100 includes a heat sink 110. Heat sink 110 is the destination of heat provided from the heat source, and transferred by the system 100. The heat sink 110 may for example comprise or otherwise be in thermal communication with a steam heat exchanger, steam boiler, or other steam generation system. The heat sink 110 may include a heat exchanger to transfer heat from the heat transfer fluid 108 to a further heat transfer fluid for process applications. The heat transfer fluid 108 may also be used directly in process applications. The heat sink 110 may be configured to heat gases, such as air for drying applications. Multiple heat transfer systems may be arranged in parallel, each dedicated to the same source and sink, sharing common fluid distribution. The systems may also be configured for different source or sink combinations, switching depending on operational needs.

[0046] The rotor assembly 102 includes a rotary compressor that compresses the working fluid 106, a rotary heat exchanger that cools the compressed working fluid 106 by exchanging heat with the heat transfer fluid 108, and an expansion system that reduces the pressure of the working fluid 106 to create a multi -phase mixture. These components are discussed in more detail below.

[0047] In some examples, the system 100 may comprise one or more controllers configured to control aspects of the system 100. For example, a controller or controllers may control at least one of: a temperature output of the system 100, a rotational speed of the rotor, internal component temperatures or pressures (e.g., within the rotary heat exchanger), systempower, working fluid mass flow, heat transfer fluid mass flow, or any other operating parameter. For example, controllers may control one or more valves or other systems for achieving such control. In this way, an operator of the system 100 may be able to customize the system 100 for a particular use case. Alternatively or additionally, the controller(s) may automatically and dynamically control such operating parameters, to continuously optimize the system operation.

[0048] In some examples, the system 100 or controller(s) thereof may receive signals from a system associated with the heat sink 110, for example indicating a desired heat flow, and may adjust the operational parameters of the system 100 accordingly. In some examples, a controller may control multiple systems 100 (or the system 100 may comprise multiple rotor assemblies 102 for transferring heat from the or multiple heat sources the or multiple heat sinks 110). Such a controller may be considered an energy arbitrage system, which may for example control heat transfer based on available electricity (e.g., electricity source such as renewable or non-renewable, and / or electricity price), and / or based on required demand.

[0049] The arrangement of components around the rotational axis enables a compact and space-efficient configuration. The integration of compression, heat exchange, and expansion functions within a unified rotating assembly reduces the overall system footprint. This consolidated design allows for flexible installation options in space-constrained environments.

[0050] The thermodynamic cycles, such as a transcritical cycle or a vapor compression cycle, enabled by this configuration provide enhanced power density compared to gas-based systems. The reduced component size and weight leads to lower manufacturing costs and mechanical loads. The vertical mounting capability further minimizes structural loading requirements.

[0051] The arrangement of the heat transfer system 100 may achieve temperature changes in the heat transfer fluid 108 (e.g., as measured between the inlet and outlet of the rotary heat exchanger) and / or in the heat sink 110 of 130°C or more, or of 150°C or more, or of 180°C or more, or of 200°C or more. Alternatively or additionally, the heat transfer system 100 may operate with efficiencies of 85% or more, or 90% or more, or 95% or more. Such temperature lifts and efficiencies may be greater than those achievable with conventional systems. As used herein, efficiency may be or comprise a coefficient of performance (COP), such as Lorenz COP (e.g., for transcritical cycles) or Carnot COP (e.g., for vapor compression cycles). Efficiency may be defined as net heating power out divided by net shaft power in,Rotor Assembly Components Overview

[0052] Figure 2 illustrates an example heat transfer system 200, similar to heat transfer system 100, including components with the rotor assembly 202. The rotor assembly 202 rotates about a rotational axis 210 and contains components for transferring heat between a working fluid 206 and a heat transfer fluid 208, as described above.

[0053] The rotor assembly 202 includes a rotary compressor 220, a rotary heat exchanger 222, and an expansion system 224. A motor 216 drives the rotation of the rotor assembly 202. The motor 216 may comprise an electric motor drive or mechanical drive from another system, and may be coupled to the rotor assembly 202 through direct coupling, magnetic coupling, chains, belts, gears, or other mechanical connection methods.

[0054] An optional boost pump 214, described below, may be included to create a pressure rise that induces flow of the working fluid 206 through the rotor assembly 202. The working fluid 206 flows through a circuit including a stationary heat exchanger 204, which transfers heat between the working fluid 206 and a heat source 218. The heat transfer fluid 208 exchanges heat with a heat sink 212, as discussed above in relation to Figure 1.

[0055] The rotary heat exchanger 222 facilitates heat transfer between the working fluid 206 and the heat transfer fluid 208. The rotary heat exchanger 222 may be configured as a counterflow arrangement where the working fluid 206 and heat transfer fluid 208 flow in opposite directions, or as a parallel flow arrangement where the fluids flow in the same direction. As discussed further below, for example in relation to Figure 3, in some examples the heat transfer system 200 may comprise a compression heat exchanger, configured to remove heat from the working fluid 108 during its compression by the rotary compressor 220. Some examples of the present disclosure may omit a rotary heat exchanger. For example some examples of heat transfer system 200 may omit the rotary heat exchanger 222. Such examples may comprise a compression heat exchanger instead of, rather than in addition to, a rotary heat exchanger. For example, sufficient heat for an application may be removed by the rotary heat exchanger alone.

[0056] The rotary compressor 220 compresses the working fluid 206 to high pressure. The rotary heat exchanger 222 transfers heat to the HTF 208, reducing the temperature of the working fluid 206 (which may, for example move the working fluid 206 into a liquid phase). Expansion system 224 allows for expansion of the working fluid 206, resulting in a multi-phase mixture.These components operate in conjunction with the rotation of the rotor assembly 202 to enable the thermodynamic cycle of the heat transfer system 200. In some examples such as that illustrated in Figure 2, the heat transfer system 200 comprises a single stage, or single circuit of the working fluid 206 through a single compressor 220, rotary heat exchanger 222, and compressor 224. Single stage systems may be more efficient than multi-stage systems, and may be mechanically simpler and physically smaller. Multi-stage systems may be used to increase the temperature lift, but the heat transfer systems of the present disclosure may achieve a high temperature lift without needing multiple stages.

[0057] In particular, the expansion system 224 expands the working fluid 206 into a multiphase mixture, comprising at least the vapor and liquid phases of the working fluid 206. As discussed further below, expanding into a multi-phase mixture means that the working fluid enters the vapor dome region of the working fluid’s pressure-temperature profile. In other words, saturation occurs, greatly increasing the density of part of the working fluid 106. Such a density increase does not occur in conventional gas-cycle based systems. For example, in a Joule gas cycle system, the density of the working fluid may change approximately 1.3x from 200C to 100C at 80bar. In a transcritical cycle at the same temperatures, as possible in the present system 100, the density may change on the order of 3.5x. In a vapour compression cycle, as also possible in the present system 100, the density may change on the order of 18x.

[0058] Taking the transcritical cycle as an illustrative example, compression of the vapor by the rotary compressor 220 may require, depending on rotor speed, on the order of 50cm radius to achieve the needed compression. Meanwhile, the density of this fluid at the exit of the rotary heat exchanger 222 means it would only flow around 2.5cm inwards before the pressure of the working fluid 106 would be that of the rotary compressor 220 inlet. The change of pressure in the expander system 224 would cause the fluid to flash into liquid and vapor components with a large volumetric expansion of around 16x and end of expansion quality of 0.15 (mass vapor / mass fluid), meaning, for these example numbers, 85% of the working fluid 106 is liquid. While the vapor could then exit the rotating system, the liquid may instead be accelerated radially outwards due to its much higher density, potentially flooding the rotary heat exchanger 222 and stopping the cycle flow. The same liquid reverse flow could happen with the vapor compression cycle.

[0059] The arrangement of components in the present system 200 may reduce such effects. For example, the expander system 224 (or any intermediary component between the rotaryheat exchanger 222 and the expander system 224) may be configured to reduce the rotational velocity of the working fluid 206. For example, the working fluid 106 may be accelerated in a direction parallel to or substantially parallel to (e.g., having a major component of acceleration parallel to) the tangential velocity of the working fluid 106. By slowing the rotational velocity of the working fluid 206, centrifugal effects discussed above may be reduced, allowing liquid working fluid 206 to more easily be extracted along with the vapor components, for example proximate to the rotational axis 210. For example, the rotational velocity of the working fluid 206 may be reduced to zero or near-zero, returning the working fluid 206 substantially to the stationary frame flow along with the stationary heat exchanger 204.

[0060] As discussed previously, the heat transfer system 100 can be configured to operate in different thermodynamic cycles, including a transcritical cycle or a vapor compression cycle. In configurations where the working fluid 206 is compressed by the rotary compressor 220 from a non-critical state into a supercritical state, the rotary heat exchanger 222 can be configured as a gas cooler heat exchanger. Alternatively, when the rotary compressor 220 compresses the working fluid 206 in a vapor phase as part of the vapor cycle, the rotary heat exchanger 222 may be configured as a condenser. The particular compression and expansion processes of various expansion cycles are discussed below in relation to Figures 12 to 17.

[0061] In the illustrated example, the system 200 comprises a boost pump 214. The boost pump 214 may for example be a gas compressor used configured to increase the pressure by a small amount to induce flow of the working fluid 206 through the rotor assembly 202. In this sense, the boost pump 214 ‘pumps’ the working fluid 206. The booster pump 214 may be a roots blower, turbine compressor, or any other type. It may comprise a pressure and / or flow regulator, depending on the expander system 224 outlet pressure and the desired stationary heat exchanger pressure. A pressure / flow regulator may also be included prior to the inlet of the stationary heat exchanger 204. For low temperature sink operation where the vapor pressure inside the vapor dome is lower too, the pressure of the working fluid 206 into the rotary compressor 220 may be increased in order to increase rotational compression effectiveness, as rotational compression is a function of fluid density. In some examples, the boost pump 214 may be positioned in the working fluid 206 circuit between the exit of the stationary heat exchanger 204 and an inlet of the rotary compressor 220, as illustrated in FIG. 2. Alternatively, the boost pump 214 may be an impeller around a drive shaft of the rotor assembly 202, which may be mounted with a fixed, outer stator. Other methods couldbe applied. In some examples the pressure may be actively controlled by the compression of the boost pump 214 or rotational speed of the inlet impeller. The impeller may include variable guide vain and other techniques to control the outlet pressure and mass flow. The boost pump 214 may be considered a meter pump for metering fluid mass flow.Rotary Compression Heat Exchange

[0062] Figure 3 illustrating an alternative configuration of a rotor assembly 302. The rotor assembly 302 includes a rotary compressor 308, a rotary heat exchanger 310, and an expansion system 314, similarly to those components described above in relation to figures 1 and 2. In this example, however, the rotary compressor 308 (or the rotor assembly 302 generally) incorporates a compression heat exchanger 316. The compression heat exchanger 316 is configured to transfer heat between the working fluid 306 and a compressor heat transfer fluid 318 during compression of the working fluid 306. The compression heat exchanger 316 allows simultaneous compression of and heat removal from the working fluid 306, providing for example a more isothermal compression process. As discussed above, some examples of heat transfer systems according to the present disclosure may comprise a compression heat exchanger such as compression heat exchanger 316, but omit a rotary heat exchanger such as rotary heat exchanger 310.

[0063] The compressor heat transfer fluid 318 flows through the compression heat exchanger 316 to remove heat from the working fluid 306 during compression. After exchanging heat in the compression heat exchanger 316, the compressor heat transfer fluid 318 may combine with the heat transfer fluid 312 from the rotary heat exchanger 310. This combination of heat transfer fluids can increase the heat energy to the sink and enhance the overall efficiency of the system. In other examples, the heat transfer 312 itself may pass through the compression heat exchanger 316. The compression heat transfer fluid 318 may be of the same or different material as the heat transfer fluid 312. In some examples, such as that illustrated in Figure 3, the compression heat transfer fluid 318 may flow through the compression heat exchanger 316 in the same direction as the working fluid 306 (parallel flow).

[0064] The compression heat exchanger 316 may allow for modification of the thermal cycle on which the heat transfer system operates. For example, heat transfer during compression can steer the process towards isothermal compression. The system may operate on modifiedtranscritical or vapor compression cycles with reduced maximum compression temperatures. Such modified thermodynamic cycles are discussed further below in relation to Figures 12 to 17.

[0065] The extraction of heat during compression through the compression heat exchanger 316 may allow a higher compression ratio to be achieved. The removal of heat during compression may increase the density of the working fluid 306, which may allow the same compression pressure to be achieved at lower rotational speeds. Lower motor RPM requirements may result in reduced power consumption for a given amount of compression.

[0066] The compression heat exchanger 316 may include all or part of the compressing fluid path, with possible heat exchange areas at the beginning, midway, or end of the compression path. The heat exchanger may be designed for the rate of heat removal from the compression process with flow paths, heat exchange surface areas, and flow velocity parameters of the heat exchanger design. The compression heat exchanger 316 may include valves to change the flow paths and flow rates for sections of the compression heat exchanger 316. These valves may be electrically actuated solenoid or other method to control operation. In this way the compression heat exchanger 316, and the heat transfer system generally, may be optimised for specific temperature and heat need regimes. For example, a built environment heat pump system may be optimised for a transcritical cycle supplying heating water or steam and then for an optimized cooling cycle.Working Fluid

[0067] The working fluid 106 (or equivalents in any of Figures 2-3) may comprise a single one or more of: halomethanes, hydrofluorocarbons, hydrofluoroolefins, and / or hydrochlorofluoroolefins. In general, the working fluid 106 for a transcritical cycle may be a substance which exhibits a critical point, and / or is compressible for most of the compression phase. Further, the working fluid 106 may be selected based at least in part on its heat capacity and / or heat capacity ratio and / or molecular mass. For example, higher heat capacity working fluids may provide improved properties for heat transfer under rotational compression, higher heat capacity ratio and / or molecular mass may provide increased pressure change and / or temperature lifts. Further, the working fluid 106 may be selected based on environmental factors, for example to minimize global warming potential and / or ozone depletion potential. The chemical groups listedabove demonstrate high performance for use in the thermodynamic cycles possible with the heat transfer systems of the present disclosure.

[0068] In some examples, Noble gases and / or conventional refrigerants (e.g., ammonia, carbon dioxide, etc.) may be included in the working fluid 106 composition. Addition of Noble gases may increase compressibility. Addition of conventional refrigerants (e.g., fluids with a higher heat capacity than the primary component of the working fluid 106) may allow the working fluid 106 to reach higher temperatures and / or operate more efficiently. For example, the working fluid 106 may comprise a mixture of a halomethane and a conventional refrigerant and / or a Nobel gas.Heat Transfer Fluid

[0069] The heat transfer fluid 108 (or equivalent in any above figure) may be an incompressible fluid, meaning it undergoes essentially no work as it enters the rotating system (e.g., proximal the rotational axis 112) and flows radially outwards towards the rotary heat exchanger 222. In some examples the heat transfer fluid 108 passes through the rotary heat exchanger 222 in a counterflow arrangement, flowing in the opposite direction through the working fluid 106. As it flows through the rotary heat exchanger 222, the heat transfer fluid 108 cools the working fluid 106 and increases in temperature. The heat transfer fluid 108 then flows radially inwards and exits the rotary system. The heat transfer flow may then be routed to a fixed heat exchanger to transfer heat to the heat sink 110. For example, for steam generation the HTF 108 may pass through a heat exchanger and pass heat to water in a separate loop, which is then heated to steam.

[0070] In the illustrated examples, the heat transfer fluid 108 is shown entering and exiting from rotary assembly 102 through rotary valves along the drive shaft of the rotor assembly 102 (represented by the black rectangles in Fig. 2, for example). Alternatively, the inlet and exit of heat transfer fluid 108 to the rotor assembly 102 may be on opposite sides of the rotor assembly 102, or both on the non-drive side.

[0071] Generally, heat transfer fluids 108 may be derived from concentrated solar thermal applications such as mineral oil, yet may be of any suitable fluid with the desired properties such as high heat capacity, low density, low viscosity, minimal safety issues, and minimal material interaction issues. For applications of steam generation, the heat transfer fluid may be water underpressure which would then be routed to a flash tank or directly to the heat application. For cooling applications, the heat transfer fluid 108 may be water, water-glycol, or other suitable water mixture, or other lower temperature heat transfer fluids with high heat capacity and low freezing points.Rotor Assembly Example

[0072] Figure 4 illustrates features of an example rotor assembly 402, similar to the rotor assemblies discussed above, and shown in perspective view without an external housing. A driveshaft 406 extends partially or fully through the rotor assembly 402, which may comprises series of flanges that transmit torque from the driveshaft 406. The flanges may provide mounting points for components including a rotary compressor with inlet 404, heat transfer fluid paths of the heat transfer system 300, a rotating heat exchanger, and an expander with outlet 408.

[0073] The flanges and heat transfer components of the rotor assembly 402 can be formed as integral components or attached using various connection methods. These methods may include diffusion bonding, bolting, or other attachment techniques to create a rigid assembly. The flanges can be rigidly connected to the driveshaft 406, with the complete unit configured to accommodate torsional forces between the compressor and expander sections.

[0074] Figure 5 shows an exploded view of the inner components that form a rotor assembly 502 according to examples of the present disclosure. The rotor assembly 502 may be the same as that shown in Figure 4.

[0075] A compressor inlet 504 is provided through which working fluid 106 enters the compressor. The compressor inlet 504 passes through a compressor end flange 506, which caps a rotary compressor 508. The rotary compressor 508 connects working fluid 106 through an HTF compressor flow channel plate 510 to a rotary heat exchanger 512. The HTF compressor flow channel plate 510, comprises a plate with flow channels for heat transfer fluid 108 exiting the rotary heat exchanger 512 (in this exemplary counterflow example, where working fluid 106 and HTF 108 flow in opposite directions through the rotary heat exchanger 512).

[0076] The rotary heat exchanger 512 is positioned between a structure flange 514 and the HTF compressor flow channel plate 510. An HTF inlet flow plate 516 comprising flow channels allows heat transfer fluid 108 to flow into the rotary heat exchanger 512. An expansion system 518 is positioned adjacent to the HTF inlet flow plate 516.

[0077] An expander outlet 520 is provided through which working fluid 106 exits both the expansion system 518 and the rotor assembly 502. The expander outlet 520 can combine multiple arms of the expansion system 518 into a single outlet path.

[0078] The arrangement of these components allows for thermal energy transfer between the working fluid 106 and heat transfer fluid 108 while maintaining separation of their respective flow paths. The structure provides mechanical support and alignment for the rotating components while enabling efficient heat transfer between the fluid streams.

[0079] The various components of rotor assembly 502 are described in more detail below.Rotor Assembly Fluid Flow Configuration

[0080] Figure 6 shows a cross-sectional view through the rotor assembly 602 described in relation to Figures 4 and 5, illustrating the fluid flow paths through the system. The rotor assembly 602 includes pathways for both working fluid 608 and heat transfer fluid 612.

[0081] Working fluid 608 enters through the compressor inlet 604 and flows into the rotary compressor 606. After compression, the working fluid 608 passes through the rotary heat exchanger 610, where thermal energy is exchanged with the heat transfer fluid 612 in a heat exchange region 614. Although shown as a single 2D area, the heat exchange region 614 can comprise an annulus extending around the rotational axis, with the illustrated region representing a partial cross-section of this annular structure.

[0082] Heat transfer fluid 612 enters the rotor assembly 602 through an HTF inlet 616 and exits through an HTF outlet 618. The HTF inlet 616 and outlet 618 are positioned along the driveshaft, and can incorporate rotary valves to control fluid flow. Alternative configurations can position the HTF inlet 616 and HTF outlet 618 on opposite sides of the rotor assembly 602, or both on the non-drive side proximal to the compressor inlet 604. The rotor assembly may comprise one or more seals, for example proximate the entrance and exits to the rotor assembly 602 and / or proximate HTF and / or working fluid inlets or exits from the rotor assembly 602. The seals may be rotary seals for sealing the rotating rotor assembly 602 while allowing fluid communication to the stationary flow paths of the HTF 612 and / or working fluid 608.

[0083] After passing through the heat exchange region 614, the working fluid 608 flows through the expansion system 620 before exiting the rotor assembly 602 via the expander outlet622. The arrangement of components creates continuous flow paths for both the working fluid 608 and heat transfer fluid 612 while maintaining their separation throughout the system.

[0084] The cross-sectional arrangement demonstrates how the working fluid 608 and heat transfer fluid 612 paths are integrated within the rotor assembly 602 to enable efficient heat transfer while maintaining mechanical integrity of the rotating structure. The configuration allows for effective thermal energy exchange between the fluid streams while accommodating the rotational motion of the assembly.Rotary Compressor Example

[0085] Figure 7 illustrates in plan view an example rotary compressor 508, of the rotor assembly 502 illustrated in FIG 5. As will be appreciated, one or more aspects of the example rotary compressor 508 may be used in any of the example systems discussed herein.

[0086] The rotary compressor 508 includes multiple radial compressor path arms 704 extending outward from a compressor inlet 702 to an outlet 706 that connects to the rotary heat exchanger. For clarity only one arm 704 is labelled. The arms 704 may be equally spaced or substantially equally spaced to provide rotational dynamic balancing. While the arrangement of compressor path arms 704 can be radially symmetric as illustrated, they may be otherwise arranged. The arms 704 may be shaped to optimize compression efficiency. Although shown with six arms 704, the rotary compressor 508 may have any number of arms, including one.

[0087] In this example, working fluid 106 enters substantially axially through the compressor inlet 702, transitions to radial outward flow through the compressor path arms 704 where it undergoes hydrostatic or pseudo-hydrostatic (radial) compression due to the rotation of the rotary compressor 508, and exits axially through outlet 706 to the rotary heat exchanger 512.

[0088] The radial compressor path arms 704 may be formed as 2D geometric profiles, facilitating manufacturing through processes such as additive plate layer manufacturing or plate machining.

[0089] The rotary compressor 508 may be shaped such that the cross-sectional area of the working fluid 106 flow path (e.g., flow paths within one or more arms 704) decreases with increasing radial distance from the rotational axis. The decreasing cross-sectional area of the flow may accommodate changes in working fluid density during compression. As the working fluid moves radially outward under rotational forces, its density increases due to compression. Theprogressive reduction in flow path area helps maintain consistent mass flow rates and enables control over fluid velocities through the compressor. For example, the flow paths within the arms 704 may be configured to maintain target flow velocities as fluid density increases during compression. These target velocities may be selected to minimize viscous and frictional losses while maintaining sufficient flow to prevent heat conduction back along the flow path. Areas between the compression flow paths can be removed to reduce the overall mass of the compressor.

[0090] Such rotary compressors 508 may provide substantially hydrostatic compression, which may approach ideal isentropic compression. For example, the arrangement may provide one or more of: low viscous losses (e.g., by lowering flow velocity); reduced surface to volume ratios, reducing drag, and / or sufficient flow velocity to substantially prevent non-negligible heat transfer in the opposite direction to the compressor flow. Such conditions may lead to the compression approximating isentropic compression, which may provide desired compression with minimal energy losses, increasing the efficiency of the heat transfer system.

[0091] The rotary hydrostatic compression provided by the rotary compressors of the present disclosure may provide direct, one step compression to the pressures needed for the transcritical cycle. For example, for a transcritical cycle, the compression ratio (e.g., for lifting temperatures from 0°C sink to transcritical) may be at least 16: 1 (pressure), and / or 14:1 (volume). For temperature lifts above 200°C, or even above 220°C in one step, compression ratio may be at least 35:1 (pressure) and / or volume ratio at least 30: 1. The single stage systems provided herein may efficiently achieve such temperature lifts. In contrast, in multi-stage systems inefficiencies in each stage may compound, reducing the overall system efficiency..Rotary Compressor Heat Exchange Example

[0092] Figure 8 shows an alternative rotary compressor 800. Rotary compressor 800 is similar to rotary compressor 508, but includes a compression heat exchanger 802. As discussed in relation to Figure 3, removing heat during compression may allow the thermodynamic cycle to be modified, for example to tailor to a particular application, and / or may increase temperature lift and / or system efficiency. As will be appreciated, one or more aspects of the example rotary compressor 800 may be used in any of the example systems discussed herein

[0093] The rotary compressor 800 includes at least one radial compressor path arm 810 configured to compress working fluid 804 as it flows through the rotary compressor 800. Therotary compressor 800 includes a compression heat exchanger 802 arranged remove heat from the working fluid 804 during compression. Working fluid 804 enters the rotary compressor 800 through compressor inlet 806 and flows along a radial compressor path arm 810 where it is compressed by rotation, as described above for rotary compressor 508. The compression heat exchanger 802, in this example integral with the same physical plate as the compressor components, can transfer heat between the working fluid 804 and a compressor heat transfer fluid 812 during the compression process. For example, compressor heat transfer fluid 812 may flow on an opposite side of the compressor plate, receiving heat from the working fluid in a parallel flow arrangement. After compression and heat exchange, the working fluid 804 exits the rotary compressor 800 through outlet 808 which connects to a rotary heat exchanger.

[0094] The compression heat exchanger 802 can be configured to maintain desired temperature conditions of the working fluid 804 during compression. As the working fluid 804 flows through the radial compressor path arm 810, the compression process generates heat. The compression heat exchanger 802 can remove this heat by circulating compressor heat transfer fluid 812 through channels or passages integrated into the compression heat exchanger 802. This arrangement allows for temperature control of the working fluid 804 as it undergoes compression.

[0095] The illustrated rotary compressor 800 shows an etched plate Printed Circuit Heat Exchanger (PCHE) unit in the compressor structure. The fluid flow may also be routed to a compressor-heat exchanger section, for example not in line with the compressor, on a different axial plan.

[0096] The rotary compressor 800 and / or compressor heat exchanger 802 may be of etched plates, waterjet or laser cut plates, or other methods. Diffusion bonding of the plates may generally mean the compressor and compressor heat exchanger become all one unit. The rotary compressor 800 and / or compressor heat exchanger 802 may also be inserted units made of plates (as above type), additive manufactured units, or other heat exchanger types, or combinations. The rotary compressor 508 may be similarly manufactured.

[0097] For a compressor heat exchanger 802 path extending the full path of the compression, the compression heat transfer fluid 812 may exit the compressor heat exchanger 802 at approximately the same temperature as the compressed working fluid 806. The compressor heat transfer fluid 812 may then be combined with then main heat transfer fluid 108 of the rotary heat exchanger 512, which may also exit near the temperature of the compressed fluid. In this way theheat removed from the compressing liquid may be additional sink heat for the heat pump cycle.The two heat transfer fluids 812, 108 may be combined at any point along their circuits.Heat Transfer Fluid Channel Plate Example

[0098] Continuing along the rotational axis of the components shown in Figure 5, Figure 9 shows a plan view of an example heat transfer fluid channel plate 510. A heat transfer fluid 108 flows through HTF path 904 from HTF inlet 902 to HTF outlet 906. A working fluid passage 908 allows working fluid 106 to flow through the structure to connect to the rotary heat exchanger 512 further along the rotational axis of the rotor assembly 502. HTF 108 enters the HTF inlet 902 from the rotary heat compressor 512.

[0099] Expansion System Example

[0100] Figure 10 shows a plan view of an example expansion system 518. The expansion system 518 includes a working fluid inlet 1002 that receives working fluid 106 from the rotary heat exchanger 512. The expansion system 518 allows the working fluid 106 to expand from its compressed state, such that it becomes a multi-phase mixture. For example, the expanded working fluid may comprise both vapor and liquid components. The expansion system 518 rotates with the other components of the rotor assembly 502, for example by being connected to the drive shaft. As will be appreciated, one or more aspects of the example expansion system 518 may be used in any of the example systems discussed herein

[0101] In some examples such as that illustrated, the expansion system 518 includes a nozzle 1004 configured to accelerate the working fluid 106. The nozzle 1004 is shaped to direct the working fluid 106 in a direction substantially opposite to the tangential velocity of the rotor assembly / working fluid 106. For example, the acceleration may be tangentially or slightly radially inwards. In this way, the rotational velocity of the working fluid 106 may be reduced. This directional acceleration facilitates extraction of the working fluid from the rotating components of the system. The expanded working fluid 106 comprises liquid, which with its larger density may otherwise accelerate outwards under rotation of the system. Reducing the rotational velocity may allow the liquid to be removed from the rotor assembly 502, rather than causing a blockage. For example, the rotational velocity may be reduced to zero, or near or approximately zero.

[0102] As illustrated, the nozzle 1004 may be at substantially the outer radius of the rotor assembly 502, and may receive the working fluid 106 from rotary heat exchanger 512 such that the working fluid 106 passes through the nozzle 1004. As shown in Figure 10, the nozzle 1004 may reduce in cross-sectional area down to a throat or minimum cross-sectional area, causing the working fluid 106 to accelerate through the throat. The nozzle 1004 may be configured for the characteristics of the working fluid 106. For example, the nozzle 1004 may be configured to avoid supersonic flow of the working fluid 106.

[0103] In addition to slowing the rotational speed of the working fluid 106 such that liquid blockage is limited, the nozzle 1004 may also recapture rotational energy (or angular momentum) from the working fluid 106. The recaptured energy may be used to help rotate the rotating components of the rotor assembly 502, reducing power required from the motor. For example, the nozzle 1004 arrangement may directly recover angular momentum by the force applied on the nozzle 1004 by the accelerating working fluid. As the nozzle 1004 is attached or integral with the expansion system 518 plate as a whole, which is connected to the driveshaft, the angular momentum may be directly reused by the rotor assembly 502.

[0104] The expansion system 518 may comprise one or more nozzles 1004, each receiving working fluid 106 from the rotary heat exchanger 512.

[0105] It is to be noted that although some expansion systems 518 comprise nozzles 1004, other examples may use other arrangements to achieve the substantially tangential acceleration.

[0106] From the nozzle 1004, the working fluid enters a channel in an expander flow path 1006, in this example a spiral flow path. The expander flow path 1006 guides the working fluid 106 from the nozzle 1004 towards the rotational axis, and thus to the expander outlet 520. As the working fluid flows through the expander flow path 1006, the pressure of the working fluid is reduced, causing the working fluid to transition to a multi-phase mixture. The multi-phase mixture exits the expansion system 518 through the expander outlet 520, and continues in its cycle back towards the stationary heat exchanger 104. Multiple expander flow paths can connect to a common central outlet 520, enabling efficient collection of working fluid 106 from multiple arms or passages while maintaining a single primary extraction point. Fixed stators may additionally or alternatively be used to guide the liquid and vapour, turning it to the axial direction to exit the rotor assembly 502 and then enter the stationary heat exchanger 104.

[0107] The expander flow paths 1006 can be formed by curved walls or passages within the expansion system 518. The geometry of the expander flow path2 1006 can be configured to control the rate of pressure reduction as the working fluid flows through the expansion system 518. The expander flow paths 1006 may be configured to maintain a significant component of tangential flow. The illustrated spiral paths may provide such a flow path.

[0108] The expansion system 518 may be formed made of plates with the area between the expander flow paths 1006 being voids to minimize mass, but in other examples this area may contain structure.Rotary Heat Exchanger Example

[0109] Figure 11 illustrates an example rotary heat exchanger 512 of the rotor assembly 502, showing a partially exploded view of the rotary heat exchanger 512. The rotary heat exchanger 512 rotates with the other components of the rotor assembly 502. As will be appreciated, one or more aspects of the example rotary heat exchanger 512 may be used in any of the example systems discussed herein

[0110] The rotary heat exchanger 512 utilizes a counter flow arrangement where working fluid 106 enters axially through inlets 1110 from the rotary compressor 508. In the illustrated example, the inlets 1110 are in the form of manifolds, connecting one inlet to multiple heat exchanger channels 1106. The working fluid 106 flows counter to the direction of rotation and radially outwards through the heat exchanger channels 1106. Heat transfer fluid 108 enters axially through HTF inlets, also in the form of manifolds in this example, from the opposite side to the working fluid 106. The HTF 108 also flows counter to the direction of rotation, but radially inwards, creating a counter flow arrangement. The rotary heat exchanger 512 can include two or more such counterflow arrangements in a stack of multiple heat exchanger layers, and while shown as generally circular, other cross-sectional shapes are possible. In other examples the rotary heat exchanger 512 may comprise only a single layer. More layers may be used for example be used where increased heat flow may be desired. Although shown as a series of layers / plates, any arrangement of rotary heat exchanger 512 may be used.

[0111] In the illustrated example, a first heat exchanger layer 1102 is shown separated from a stack of further layers 1116. In an assembled system, all layers are combined in the stack. Each heat exchanger layer 1102 can be constructed as a plate disk with heat exchanger elements in theouter annulus area. The disk structure can include cutouts to reduce mass and allow for optimum supporting spoke shapes. The structure can be manufactured from stainless steel or other suitable high-strength metals. The working fluid 106 and heat transfer fluid 108 interface can comprise copper or materials with similar thermal expansion properties to the structure material, enabling bonding into a unified structure. The heat exchanger layers can be formed from layers of stainless steel and copper, with the copper forming a continuous annulus or sectors thereof. Flow channels can be cut into the structural plate to optimize fluid heat exchange areas and fluid flow. The plates may for example be cut by water jet, laser, EDM, or other any other method. The structural disc may have the heat exchanger flow channels chemically etched, while the structural cuts may be of any method. One or more layers, or components thereof, may be etched plate printed circuit heat exchangers, additive manufactured, or other type of heat exchanger.

[0112] As shown in Figure 11, the first heat exchanger layer 1102 of this example comprises a flow channel plate 1104. The flow channel plate 1104 includes heat exchanger channels 1106 through which working fluid 106 and HTF 108 flow to facilitate heat exchange. The heat exchanger channels 1106 run around the flow channel plate 1104, and can extend either partially or substantially around the full circumference. In some example, as illustrated, there may be multiple heat exchanger channel 1106 sections, each section running partially around the circumference of the flow channel plate 1104, and each connecting between a working fluid inlet 1110 and working fluid outlet 1112. Each section may be of the same length, as illustrated, or may be of different lengths. Such an arrangement may allow working fluid to be received from at multiple circumferential positions from the rotary compressor 508, for example corresponding to the multiple compressor path arms 810 of the rotary compressor 508. In the illustrated example, an end plate 1108 caps the heat exchanger channels 1106 of the flow channel plate 1104, forming a complete unit.

[0113] Working fluid 106 enters the heat exchanger channels 1106 of a given heat exchanger layer through a working fluid inlet 1110. The working fluid then exits the heat exchanger channels through a working fluid outlet 1112, from where it can either pass through to another heat exchanger layer or exit the heat exchanger to the expander. Working fluid 106 may flow through the heat exchanger channels 1106 of any number of heat exchanger layers. The HTF outlet 1114 provides an exit path for the heat transfer fluid 108 after heat exchange has occurred. The HTF 108 may also flow within any number of heat exchanger layers.

[0114] As discussed previously, when the system operates on a transcritical cycle, or modifications thereof, the rotary heat exchanger 512 may be considered a gas cooler. In such examples, the rotary heat exchanger 512 may receive working fluid 106 in a supercritical state. In some examples the rotary heat exchanger 512 may cool the working fluid 106, by transfer of heat to the HTF 108, into a subcritical state (e.g., such that it becomes a liquid), but still outside of the vapor dome - i.e., cooling without a phase change / crossing a phase boundary. The expansion system 518 may then reduce the pressure of the working fluid 106 by expansion, crossing into the vapor dome and forming a multi-phase fluid. In other examples, the rotary heat exchanger 512 may cool such that the working fluid 106 remains in the supercritical state. The rotary heat exchanger 512 may be configured to remove a certain amount of heat from the working fluid 106 for the intended heat lift of a given application (e.g., by configuring the number of heat exchanger layers and / or total flow path of the working fluid within the rotary heat exchanger 512), and the form the resulting output working fluid may then depend on that temperature change.

[0115] When the system operates on a vapor cycle, or modification thereof, the rotary heat exchanger 512 may be considered a condenser. In such examples, the rotary heat exchanger 512 may receive the working fluid 106 in subcritical, vapor state, for example a superheated vapor (e.g., high temperature and / or pressure such that the working fluid is to the right (higher entropy) side of the vapor dome on a TS plot). The rotary heat exchanger 512 may cool the working fluid 106 such that is undergoes a phase transition, e.g., entering the vapor dome, at least partially condensing into a liquid. The working fluid 106 may then reject latent heat to the HTF 108. In some examples, the rotary heat exchanger 512 may be configured to continue to cool the working fluid 106 such that it becomes a supercooled fluid, e.g., finishing outside of the vapor dome.

[0116] As will be appreciated, the rotary heat exchanger 512 may be configured for particular working fluid(s), particular applications, and / or particular thermodynamic cycles, to remove a desired amount of heat from the working fluid 106 based on such considerations.

[0117] As discussed above, in some examples the rotary heat exchanger 512 may be configured such that the working fluid 106 moves radially outwards as it passes through the rotary heat exchanger 512. For example, a working fluid output may be at the same or greater radial position to a corresponding working fluid input. Such an arrangement may facilitate flow of the working fluid through and out of the rotor assembly 502.

[0118] Components of the rotary heat exchanger 512, e.g., one or more of the layers, may be formed of etched plates, water jet or laser cut plates, or other methods. Alternatively, the heat exchanger units may be placed into the rotating heat exchanger structure. These heat exchanger units may be of etched plate printed circuit heat exchangers, additive manufactured, or other type of heat exchanger.Example Thermodynamic Cycles

[0119] Figures 12-17 illustrate example thermodynamic cycles that be used with any of the heat transfer systems of this disclosure. Although particular examples are shown, it is to be appreciated that any cycle may be used, for example as tailored to a particular application, in which expansion results in a multi-phase mixture (e.g., in which expansion crosses a saturation line / undergoes a phase transition, expanding into the vapor or saturation dome).

[0120] Figures 12 and 13 show an example transcritical cycle, with four different views of the same cycle. Figure 12(a) shows a temperature-entropy (T-S) plot. Figure 12(b) shows a pressure-enthalpy (P-H) plot. Figure 13(a) shows a temperature-density (T-d) plot. Figure 13(b) shows a pressure-specific volume (P-V) plot. Each plot shows a dashed line indicating the boundary of the vapor dome (where being ‘inside’ the vapor dome means being in the area bound by the dashed line and the x-axis). The boundary is the saturation line, crossing into which indicates a phase transition involving saturation. Within the vapor dome, the fluid is in a mixed phase state comprising liquid and vapor. The top of the vapor dome, i.e., the highest y-value on the dashed line, represents the critical point. Above this y-value, the fluid is in a supercritical state in which there is no difference between liquid and vapor. Below the critical point the fluid is in a subcritical state, which may for example be vapor, liquid, or a combination of both, depending on the x-y position in the plot.

[0121] Each plot in Figures 12 and 13 also shows a solid line representing a thermodynamic cycle through which the working fluid 108 may be passed by the systems described herein. Various points 1-5 are labelled on each plot. The same numbered point represents the same condition of the working fluid on each plot. For ease of discussion the following will focus on the T-S plot of Figure 13(a), but it is to be appreciated that the cycle also varies other thermodynamic properties of the working fluid as shown by the other plots.

[0122] Considering the T-S plot of Figure 12(a), point 1 represents the working fluid 106 on the exit from the stationary heat exchanger 104. The working fluid 106 is in a vapor state, having received heat from the heat source 218 via the stationary heat exchanger 104. In some examples, a boost pump 214 is positioned between the stationary heat exchanger 104 and the rotor assembly 102, represented by position 2 in the plot. The boost pump 214 may be a small gas vapor compressor which regulates mass flow and / or heat pump power. The boost pump 214 ‘pumps’ fluid around the system, as discussed above.

[0123] Point 2 to point 3 on the plot represents rotary compression of the working fluid 106 by the rotary compressor 220 (or any rotary compressor discussed herein). The compression raises the temperature of the working fluid 106, without significantly changing its entropy. As discussed above, the systems of the present disclosure may achieve near isentropic compression, which may maximize efficiency and minimize energy loss. The temperature and pressure increases from compression raise the working fluid 106 above the critical point, resulting in a supercritical fluid.

[0124] Point 3 to point 4 on the plot represents removal of heat from the working fluid to the heat transfer fluid 108 in the rotary heat exchanger 222 (or any rotary heat exchanger discussed herein). The heat removal reduces the temperature and entropy of the working fluid 106, but as can be seen in Figure 12(b) keeps pressure substantially constant (i.e., keeping the working fluid 106 compressed). As can be seen, during this heat removal the working fluid 106 in this example remains outside of the vapor dome, cooling to a subcritical liquid by point 4.

[0125] Point 4 to point 5 on the plot represents expansion by the expansion system 224 (or any expansion system discussed herein). Expansion reduces the pressure and temperature such that the working fluid 106 enters the vapor dome, experiencing a phase transition, and resulting by point 5 in a mixture of fluid in the liquid phase and in the vapor phase. It is noted that there may be some components of the working fluid or other materials in the solid phase within this mixture.

[0126] Point 5 to point 1 on the plot represents passage of the working fluid 106 out of the rotating system and back to the stationary heat exchanger 104 (or evaporator), which evaporates liquid components of the working fluid, leaving substantially only a vapor to start the cycle again.

[0127] Figure 14 illustrates a T-S plot for an example vapor cycle that may be used with any of the systems discussed herein. Point 1 on this plot represents the working fluid at the exit of the stationary heat exchanger 104, as for the example transcritical cycle discussed above forFigures 13 and 14. At this point the working fluid is substantially in the vapor phase, but may include a liquid component. From point 1 to point 2, the boost pump 214 ‘pumps’ the working fluid 106, and the resulting vapor enters the rotor assembly 102.

[0128] Point 2 to point 3 on the plot represents rotary compression of the working fluid 106 by the rotary compressor 220 (or any rotary compressor discussed herein). As above, compression raises the temperature and pressure of the working fluid 106. In this case, however, the compression does not raise the working fluid 106 above the critical point, so the vapor remains subcritical. For example, there may be applications where the additional compression required to achieve the supercritical state is not needed for the desired temperature lift and / or efficiency, so the vapor cycle may be used instead of the transcritical cycle.

[0129] Point 3 to point 4 on the plot represents removal of heat from the working fluid to the heat transfer fluid 108 in the rotary heat exchanger 222 (or any rotary heat exchanger discussed herein). The heat removal first reduces the temperature of the working fluid 106 such that it experiences a phase transition, entering the vapor dome. Thus the rotary heat exchanger 222 may be considered a condenser. Further heat is then removed by removal of latent heat from the working fluid, as shown by the substantially horizontal transition in the plot. In this example, the rotary heat exchanger 222 is configured to continue to remove heat from the working fluid 106, such that the working fluid 106 is supercooled, exiting the vapor dome and resulting in a supercooled liquid at the end of heat exchanger. Other examples may not continue cooling to the supercooled region, instead resulting in a vapor and gas mixture even before expansion.

[0130] Point 4 to point 5 on the plot represents expansion by the expansion system 224 (or any expansion system discussed herein). Expansion in this example brings the working fluid 106 into the vapor dome, resulting in a multi-phase mixture. In examples without supercooling, the expansion may be from multi -phase mixture to multi -phase mixture, i.e., the expansion is still into a multi-phase mixture.

[0131] Point 5 to point 1 on the plot represents passage of the working fluid 106 out of the rotating system and back to the stationary heat exchanger 104 (or evaporator).Example Modified Thermodynamic Cycles

[0132] As discussed above, components of the systems disclosed herein may allow the thermodynamic cycles illustrated in Figures 12-14 to be modified, allowing the properties of thesystems to be tailored to particular characteristics or applications. For example, removing heat from the working fluid 106 during the compression stage, for example by the compression heat exchanger 316 (or any compression heat exchanger discussed herein) may allow for modification of the cycles.

[0133] For example, the compressor heat exchanger 316 may allow the path of the compression to optimized for the application. Normally, for wet fluids (negative slope on the right side of the dome in the T-S plot), the lower the evaporator temperature, the higher the resultant compressor temperature. Fig 12(a) for example shows a T-S plot of a standard (i.e., unmodified) transcritical cycle with an example output temperature of around 200°C (point 3). Often, however, industrial heat (temperature lift) needs are in the 130°C-180°C range. By removing heat from the working fluid 106 during compression, the maximum temperature could be moderated to the application need. For example, Figure 15 shows a T-S plot of a modified transcritical cycle (black line), against the standard transcritical cycle (grey line) of Figure 12(a). In this example, removing heat ‘bends’ the compression line from points 2 to 3, raising the working fluid to a lower maximum temperature of around 180°C, yet still have the source evaporator at lower temperatures (shown at 0°C).

[0134] The compression heat transfer fluid 318 exits the compression heat exchanger 316 at approximately the same temperature as the rotary heat exchanger heat transfer fluid 108. These HTFs 318, 108 may be combined for use as heat for the application. Rotational compression is a function of fluid density, rpm, and radius. With the compression heat exchanger 316, the density of the fluid may be increases approximately lOx - 50x, depending on path. This means to achieve the same end of compression pressure, the rotational velocity (RPM) may be reduced.

[0135] The Coefficient of Performance (COP) of a heat pump is heat power out / shaft power in. Through the use of the compression heat exchanger 316, the numerator (heat out) may be increased while the denominator may be decreased. This results in a greater COP of the heat pump system.

[0136] The rotor assembly 102 may tolerate wet compression, meaning the same principles of the compression heat exchanger 316 use can be applied to isentropic and dry fluids.

[0137] Figure 16 shows an example modified vapor compression cycle. The solid black line represents the modified cycle, the solid grey line represents the standard cycle shown in Figure 14. Modified vapor compression may include reducing or minimizing the maximum temperatureof compression, and / or reducing or minimizing the exergy (useful energy) losses for a more efficient heat pump cycle of sink temperatures less than the critical temperature. The compression heat exchanger 316 may be used to achieve a cycle such as shown in Figure 16. This cycle may be suited for cooling applications where the compression power required is reduced / minimized while the sink temperature may be maintained at optimum temperatures for sink heat flow, such as 20°C above the air temperature for applications of pure cooling, where the heat energy is dissipated to ambient air. Area within the curves of the two (modified and unmodified) cycles is indicative of the relative power requirements for the same cooling power where the evaporator (points 5 to 1) heat intake is the same for both cycles.

[0138] This modified cycle could be for example used in a specifically design heat pump system dedicated to cooling, or a cooling - steam generating heat pump when high temperature sink is not required, then optimized cooling.

[0139] Figure 17 represents further example compression lines for a modified transcritical cycle. Although certain examples have been provided, it is to be appreciated that any such modification is possible to tailor to desired applications.

[0140] Figure 17 shows four different example end points of compression (A-D), which may be modified versions of the compression line of point 2 to point 3 in the standard transcritical cycle. Path A removes heat during compression yet remains outside of the vapour dome. The path may end at greater pressure as shown, or, with reduced RPM, end at the same pressure as conventional rotary compression. Path B compresses along the vapour dome boundary where the desired change in density for given change in enthalpy is generally greatest, while maintaining a purely gaseous state. Path C crosses the vapor dome then exits the dome near the critical point. Path D is a highly modified compression path across the vapour dome to include supercooling. Similar modifications may be made to vapor cycle examples. After compression, the modified cycles may undergo rotary heat exchange and expansion into a multi-phase mixture as for the standard cycle discussed above.

[0141] In some examples of the systems discussed herein, the system may be able to operate on different thermodynamic cycles at different times. For example, control elements within the heat transfer systems may modify operation to change the thermodynamic cycle being used, e.g. by altering power, mass flow, rotor speed, flow path length through heat exchangers, amount of heat removed during compression and / or by the rotary heat exchanger, etc. For example, thesystem may comprise a controller configured to adjust the thermodynamic cycle on which the system is operating. As an illustrative example, the system may be configured for cooling using the vapor cycle in the summer, and heating using the transcritical cycle during the winter.Heat Transfer Method Implementation

[0142] Figure 18 illustrates a flow diagram depicting a method of transferring heat between a working fluid and a heat transfer fluid. The method includes multiple operations that can be performed in sequence. The method of Figure 18 may be performed using any of the heat transfer systems and / or components thereof discussed in this disclosure.

[0143] At block 1802, a working fluid undergoes compression through rotational compression. The rotational compression can be achieved using any type of rotary compressor.

[0144] Following compression, at block 1804, heat is exchanged between the working fluid and a heat transfer fluid using a rotating (rotary) heat exchanger. The rotating heat exchanger can incorporate various designs that facilitate heat transfer while maintaining rotational movement, such as rotating drum heat exchangers or rotating plate heat exchangers.

[0145] At block 1806, the working fluid undergoes expansion. The expansion process can be implemented using different types of expansion devices, such as expansion valves, turbines, or other suitable expansion mechanisms.

[0146] The expansion process continues at block 1808, where the working fluid transitions to a multi-phase mixture. This transition can result in the working fluid existing simultaneously in different phases, such as liquid and vapor phases. The multi-phase mixture can form through various mechanisms, including pressure reduction, temperature changes, or a combination thereof.

[0147] The method can be implemented in various thermal systems where heat transfer between fluids is desired. The working fluid and heat transfer fluid can be selected based on specific application requirements, such as operating temperatures, pressures, and thermal properties. The method can be modified to accommodate different operating conditions and system configurations while maintaining the described sequence of compression, heat exchange, and expansion steps.

[0148] The method may further comprise any of the processed discussed above in relation to system components, including for example removing rotational velocity from the working fluid during or before expansion; and / or removing heat from the working fluid during compression.Example Applications

[0149] Heat sources for the systems and methods discussed herein could include ambient air, refrigeration system, a geothermal heat source, a waste heat stream from a process, a wastewater or waste heat stream from a heat system, a power system, or a combined heat and power system, a carbon capture process, a body of water, a district energy system, a solar thermal heat source, a nuclear reactor, a body of water such as a lake or a river, a carbon capture process direct air capture system, condenser heat from a cooling system, cool thermal storage, cooling application such as air conditioning, cooling, refrigeration, or freezing, or other heat source.

[0150] For many source applications, the stationary heat exchanger / evaporator may have a secondary heat transfer fluid loop running to and from the heat source(s). This may for example generally be a water-glycol loop, but other heat transfer fluids may be used.

[0151] The working fluid may run directly to, for example, air heat exchangers or solar thermal panels in direct expansion. The heat source fluid flow may also be routed directly through the stationary heat exchanger (evaporator) for heat sources such as waste heat, geothermal, solar thermal heated fluid, etc. For cooling applications, the working fluid may be used directly, or an intermediate loop may be used with a refrigerant, water-glycol, or other low temperature heat transfer fluid. Motor and power electronics of the heat pump system could be used to supplement the heat source.

[0152] In an air source heat pump to steam arrangement, for example, the air heat exchanger may generally be exterior to the heat pump system enclosure. For any arrangement and application, the evaporator and steam generator unit may also be exterior to the heat pump system enclosure.

[0153] The heat transfer system may include a combination of heat sources, used in conjunction or separately. Some examples may provide for switching between heat sources.

[0154] For the modified vapor compression cooling cycle, the HTF routed through the rotor may for example be water-glycol or other heat transfer fluid which then runs to a heat exchanger to dissipate heat, this heat exchanger may be of any type and include a secondary loop.

[0155] A heat pump system may be configured to provide cooling to a refrigeration system when the heat pump system load is low and / or near zero.

[0156] In some examples, a system may comprise one or more heat transfer systems as disclosed here, and one or more alternative systems such as a conventional refrigeration system. The system may comprises a controller configured to determine which system(s) to operate at a given time. For example, in a refrigeration system, if a heat pump system load is zero, then an aircooled condenser, a condenser water loop, and / or other source may be used instead to cool the refrigeration system.

[0157] The systems discussed herein may be mounted within a container, which may contain all or a subset of the system components. For air source systems, the air heat exchangers could be mounted atop, atop adjacent buildings, in dedicated heat exchanger arrays, or other arrangements, exterior to the container. Depending on sizing, the source and sink heat exchangers may be mounted external to the container. The system could be skid-mounted to allow installation in industrial facilities, buildings, etc. The system could also be configured for shipboard applications. The system could be used for direct air capture systems, using process heat as the source and sink for the process needs. For many batch operations or variance in electricity prices and source of electricity production, cold and hot storage systems may be used, to include steam storage.

[0158] The heat sink may be a steam heat exchanger type, steam boiler type, or other steam generation system. This may also be a heat exchanger, from heat transfer fluid to second heat transfer fluid that is used in a process application. The heat pump heat transfer fluid may also be used directly in the process application, negating the need for the heat exchanger. The heat exchanger may also be used to heat a gas, such air for drying applications. The heat pump systems may be used in parallel, with each dedicated to the same source and sink, sharing common fluid distribution. The systems may also be used for different source or sink combinations, switching, depending on needs.

[0159] Water may be used as the heat transfer fluid in the rotary system, kept under pressure and then used in the application as superheated water or flashed for steam use. The heat transfer fluid may directly or indirectly provide heat energy to a thermal storage system.

[0160] The sink heat may be used to heat steam for steam recompression systems.

[0161] Applications for the heat pump system may include any combination of the source and sink flows listed or other sources and sinks, within the capabilities of the heat pump. Someexamples may comprise switching between sources and sinks depending on user needs, source availability and needs, and / or power availability.

[0162] Some example applications may include air source to 180°C steam heat pump for paper and pulp industry; -10°C freezing to 200°C heat transfer fluid for food industry freezing and baking, e.g., with the heat transfer oil or super critical water routed to the ovens; or building or community heat pumps, for providing cooling and heating, optimized for cooling with the modified vapour compression cycle in the summer months and building heating with supercritical water or steam in the winter.

[0163] The heat pump system may also be used in series with steam recompression systems to create steam at higher temperatures than the heat pump output. In this, water may be raised in temperature part or all the way from ambient to the heat pump outlet temperature, then raised through the steam recompression systems. Alternatively, the heat pump may be used to heat an intermediate pressurized water or steam, raising that temperature, then use of the steam recompression systems. The heat pump may be used to create steam that is then stored, then used in steam recompression systems.

[0164] The heat pump system may be in conjunction with thermal energy storage systems, to include for example sensible and latent heat systems. This may include cold and or hot storage.

[0165] The heat source for the heat pump may be ambient air where the air heat exchangers may require periodic defrosting. This may be done with any method know in the industry to include electric resistance heaters, heating the air heat exchanger structure or air over the heat exchangers. The high temperature heat transfer fluid may be used to defrost the air heat exchangers, periodically routing hot flow, which may be mixed with cold fluid to achieve the needed temperature, through the air heat exchangers. The defrosting may be via charging for thermal storage and then discharging for defrosting. An addition fluid loop may be used to defrost the air heat exchanger(s) where this fluid is heated by the high temperature fluid. Defrosting of multiple air source heat exchangers may be sequentially, simultaneously, or other combination.

[0166] A heat exchanger described herein may refer to, or be, a shell and tube heat exchanger, a brazed plate, a welded plate, etched plate, PCHE, a gasketed plate, a plate-fin, microtube, of the type described herein, or other heat exchanger method. Any heat exchanger used herein may comprise multiple combined heat exchangers, for example in series.

[0167] While the foregoing description provides specific embodiments of the invention, it will be understood that various modifications, variations, and alternatives may be made without departing from the spirit and scope of the invention as defined by the following claims. The described embodiments are illustrative and not intended to be limiting; features from different embodiments may be combined, and modifications may be made to adapt the invention to particular uses or implementations. Additionally, functional equivalents of the described elements may be substituted, and certain steps or components may be omitted, added, or reordered while still achieving substantially the same results.

[0168] The following statements define further statements of invention:

[0169] 1. A heat transfer system for exchanging heat between a working fluid and a heat transfer fluid, the heat transfer system comprising: a stationary heat exchanger for exchanging heat between the working fluid and a heat source; and a rotor assembly arranged around a rotational axis, the rotor assembly comprising: a rotary compressor in fluid communication with the stationary heat exchanger, the rotary compressor configured to compress the working fluid; a rotary heat exchanger for exchanging heat between the working fluid and the heat transfer fluid, the rotary heat exchanger configured to cool the compressed working fluid; and an expansion system in fluid communication with the stationary heat exchanger, the expansion system configured to reduce a pressure of the working fluid such that the working fluid expands into a multi-phase mixture.

[0170] 2. The heat transfer system of clause 1 , wherein the rotor assembly comprises a single rotary heat exchanger.

[0171] 3. The heat transfer system of clause 1 or clause 2, wherein the rotary compressor compresses the working fluid from a non-critical state into a supercritical state.

[0172] 4. The heat transfer system of clause 3, wherein the rotary heat exchanger is configured to cool the compressed working fluid from the supercritical state.

[0173] 5. The heat transfer system of any preceding clause, wherein the rotary heat exchanger comprises a gas cooler heat exchanger.

[0174] 6. The heat transfer system of clause 1 or clause 2, wherein rotary compressor compresses the working fluid in a vapor phase.

[0175] 7. The heat transfer system of clause 6, wherein the rotary heat exchanger comprises a condenser.

[0176] 8. The heat transfer system of any preceding clause, wherein the expansion system is configured to reduce a rotational velocity of the working fluid.

[0177] 9. The heat transfer system of any preceding clause, wherein the expansion system is configured to accelerate the working fluid in a direction opposite to a tangential velocity of the working fluid.

[0178] 10. The heat transfer system of clause 9, wherein the expansion system comprises a nozzle, the nozzle shaped to accelerate the working fluid in the direction opposite to the tangential velocity, and wherein the expansion system is shaped to direct the working fluid from the rotary heat exchanger through the nozzle.

[0179] 11. The heat transfer system of clause 10, wherein the expansion system comprises one or more channels arranged to direct working fluid from the nozzle towards the rotational axis.

[0180] 12. The heat transfer system of clause 11, wherein the one or more channels provide a spiral flow path for the working fluid.

[0181] 13. The heat transfer system of any of clauses 10 to 12, wherein the nozzle is arranged such that rotational energy extracted from the working fluid passing through the nozzle is recovered by the rotor assembly.

[0182] 14. The heat transfer system of any preceding clause, wherein the working fluid exits the rotor assembly from a radial position at or proximate to the rotational axis.

[0183] 15. The heat transfer system of any preceding clause, wherein the rotary compressor comprises a compression heat exchanger configured to transfer heat to or from the working fluid as the working fluid is compressed by the rotary compressor.

[0184] 16. The heat transfer system of any preceding clause, wherein the rotary compressor is shaped such that a cross-sectional area of a flow path of the working fluid through the rotary compressor decreases as radial position away from the rotational axis increases.

[0185] 17. The heat transfer system of any preceding clause, wherein the working fluid comprises one or more of: a halomethane, a hydroflueorcarbon, a hydrofluoroolefin, and / or a hydrochlorofluoroolefin.

[0186] 18. The heat transfer system of clause 17, wherein the working fluid further comprises a noble gas and / or a refrigerant.

[0187] 19. The heat transfer system of any preceding clause, wherein the rotary heat exchanger is arranged such that an inlet of the rotary heat exchanger for receiving working fluid from the rotary compressor is at a same or lesser radial position to an outlet of the rotary heat exchanger for transferring working fluid to the expansion system.

[0188] 20. The heat transfer system of any preceding clause, wherein an input to the rotary heat exchanger is positioned radially outward of the rotary compressor and wherein the rotary heat exchanger extends substantially parallel to the rotational axis.

[0189] 21. The heat transfer system of clause 20, wherein the input to the rotary heat exchanger is at a smaller radial position than an output of the rotary heat exchanger.

[0190] 22. The heat transfer system of any preceding clause, wherein the heat transfer system is configured to change a temperature of the heat transfer fluid by at least 150°C.

[0191] 23. The heat transfer system of any preceding clause, wherein an efficiency of the heat transfer system is at least 85%.

[0192] 24. The heat transfer system of any preceding clause, wherein the heat transfer system is a heat pump.

[0193] 25. The heat transfer system of any preceding clause, wherein the heat transfer system is configured to operate in a trans-critical cycle or a vapor compression cycle of the working fluid.

[0194] 26. A method of transferring heat between a working fluid and a heat transfer fluid, the method comprising: compressing the working fluid by rotational compression; exchanging, by a rotating heat exchanger, heat between the working fluid and the heat transfer fluid with the working fluid; and expanding the working fluid such that the working fluid expands into a multi-phase mixture.

[0195] 27. The method of clause 26, wherein the working fluid is in a vapor state or a multi-phase state prior to rotational compression.

[0196] 28. The method of clause 26 or clause 27, comprising removing heat from the working fluid during rotational compression.

[0197] 29. The method of clause 28, comprising transferring heat from the working fluid to the heat transfer fluid during rotational compression.

[0198] 30. The method of any of clauses 26 to 29, comprising compressing the working fluid into a supercritical state.

[0199] 31. The method of clause 30, comprising cooling, by the rotating heat exchanger, the working fluid from the supercritical state.

[0200] 32. The method of any of clauses 26 to 29, comprising compressing the working fluid in a vapor phase.

[0201] 33. The method of clause 32, wherein the rotating heat exchanger comprises a condenser.

[0202] 34. The method of any of clauses 26 to 33, further comprising exchanging heat between the working fluid and a heat source in a non-rotating heat exchanger.

[0203] 35. The method of any of clauses 26 to 34, further comprising: reducing a rotational velocity of the working fluid to a reduced rotational velocity; and removing the working fluid from a rotational system at the reduced rotational velocity.

[0204] 36. A heat transfer system for exchanging heat between a working fluid and a heat transfer fluid, the heat transfer system comprising: a rotor assembly arranged around a rotational axis, the rotor assembly comprising: a rotary compressor configured to compress the working fluid; a heat exchanger for exchanging heat between the working fluid and the heat transfer fluid; and an expansion system in fluid communication with the stationary heat exchanger, the expansion system configured to reduce a pressure of the working fluid such that the working fluid expands into a multi-phase mixture.

[0205] 37. The heat transfer system of clause 36, wherein the heat exchanger comprises one or more of: (i) a rotary heat exchanger configured to cool the compressed working fluid; or (ii) a compression heat exchanger configured to remove heat from the working fluid during compression of the working fluid.

[0206] 38. The heat transfer system of clause 36 or clause 37, wherein the heat transfer system is configured to operate on a transcritical cycle or a vapor compression cycle.

[0207] Any of clauses 36 to 38 may comprise or further comprise the subject-matter of any of the clauses 2-25, either alone or in combination.

Claims

WHAT IS CLAIMED IS:

1. A heat transfer system for exchanging heat between a working fluid and a heat transfer fluid, the heat transfer system comprising: a stationary heat exchanger for exchanging heat between the working fluid and a heat source; and a rotor assembly arranged around a rotational axis, the rotor assembly comprising: a rotary compressor in fluid communication with the stationary heat exchanger, the rotary compressor configured to compress the working fluid; a rotary heat exchanger for exchanging heat between the working fluid and the heat transfer fluid, the rotary heat exchanger configured to cool the compressed working fluid; and an expansion system in fluid communication with the stationary heat exchanger, the expansion system configured to reduce a pressure of the working fluid such that the working fluid expands into a multi-phase mixture.

2. The heat transfer system of claim 1 , wherein the rotor assembly comprises a single rotary heat exchanger.

3. The heat transfer system of claim 1, wherein the rotary compressor compresses the working fluid from a non-critical state into a supercritical state.

4. The heat transfer system of claim 3, wherein the rotary heat exchanger is configured to cool the compressed working fluid from the supercritical state.

5. The heat transfer system of claim 1, wherein the rotary heat exchanger comprises a gas cooler heat exchanger.

6. The heat transfer system of claim 1 , wherein rotary compressor compresses the working fluid in a vapor phase.

7. The heat transfer system of claim 6, wherein the rotary heat exchanger comprises a condenser.

8. The heat transfer system of claim 1, wherein the expansion system is configured to reduce a rotational velocity of the working fluid.

9. The heat transfer system of claim 1, wherein the expansion system is configured to accelerate the working fluid in a direction opposite to a tangential velocity of the working fluid.

10. The heat transfer system of claim 9, wherein the expansion system comprises a nozzle, the nozzle shaped to accelerate the working fluid in the direction opposite to the tangential velocity, and wherein the expansion system is shaped to direct the working fluid from the rotary heat exchanger through the nozzle.

11. The heat transfer system of claim 10, wherein the expansion system comprises one or more channels arranged to direct working fluid from the nozzle towards the rotational axis.

12. The heat transfer system of claim 11, wherein the one or more channels provide a spiral flow path for the working fluid.

13. The heat transfer system of claim 10, wherein the nozzle is arranged such that rotational energy extracted from the working fluid passing through the nozzle is recovered by the rotor assembly.

14. The heat transfer system of claim 1, wherein the working fluid exits the rotor assembly from a radial position at or proximate to the rotational axis.

15. The heat transfer system of claim 1, wherein the rotary compressor comprises a compression heat exchanger configured to transfer heat to or from the working fluid as the working fluid is compressed by the rotary compressor.

16. The heat transfer system of claim 1, wherein the rotary compressor is shaped such that a cross-sectional area of a flow path of the working fluid through the rotary compressor decreases as radial position away from the rotational axis increases.

17. The heat transfer system of claim 1, wherein the working fluid comprises one or more of: a halomethane, a hydroflueorcarbon, a hydrofluoroolefin, and / or a hydrochlorofluoroolefin.

18. The heat transfer system of claim 17, wherein the working fluid further comprises a noble gas and / or a refrigerant.

19. The heat transfer system of claim 1, wherein the rotary heat exchanger is arranged such that an inlet of the rotary heat exchanger for receiving working fluid from the rotary compressor is at a same or lesser radial position to an outlet of the rotary heat exchanger for transferring working fluid to the expansion system.

20. The heat transfer system of claim 1 , wherein an input to the rotary heat exchanger is positioned radially outward of the rotary compressor and wherein the rotary heat exchanger extends substantially parallel to the rotational axis.

21. The heat transfer system of claim 20, wherein the input to the rotary heat exchanger is at a smaller radial position than an output of the rotary heat exchanger.

22. The heat transfer system of claim 1 , wherein the heat transfer system is configured to change a temperature of the heat transfer fluid by at least 150°C.

23. The heat transfer system of claim 1, wherein an efficiency of the heat transfer system is at least 85%.

24. The heat transfer system of claim 1 , wherein the heat transfer system is a heat pump.

25. The heat transfer system of claim 1, wherein the heat transfer system is configured to operate in a trans-critical cycle or a vapor compression cycle of the working fluid.

26. A method of transferring heat between a working fluid and a heat transfer fluid, the method comprising: compressing the working fluid by rotational compression; exchanging, by a rotating heat exchanger, heat between the working fluid and the heat transfer fluid with the working fluid; and expanding the working fluid such that the working fluid expands into a multi-phase mixture.

27. The method of claim 26, wherein the working fluid is in a vapor state or a multi-phase state prior to rotational compression.

28. The method of claim 26, comprising removing heat from the working fluid during rotational compression.

29. The method of claim 28, comprising transferring heat from the working fluid to the heat transfer fluid during rotational compression.

30. The method of claim 26, comprising compressing the working fluid into a supercritical state.

31. The method of claim 30, comprising cooling, by the rotating heat exchanger, the working fluid from the supercritical state.

32. The method of claim 26, comprising compressing the working fluid in a vapor phase.

33. The method of claim 32, wherein the rotating heat exchanger comprises a condenser.

34. The method of claim 26, further comprising exchanging heat between the working fluid and a heat source in a non-rotating heat exchanger.

35. The method of claim 26, further comprising: reducing a rotational velocity of the working fluid to a reduced rotational velocity; and removing the working fluid from a rotational system at the reduced rotational velocity.

36. A heat transfer system for exchanging heat between a working fluid and a heat transfer fluid, the heat transfer system comprising: a rotor assembly arranged around a rotational axis, the rotor assembly comprising: a rotary compressor configured to compress the working fluid; a heat exchanger for exchanging heat between the working fluid and the heat transfer fluid; and an expansion system in fluid communication with the stationary heat exchanger, the expansion system configured to reduce a pressure of the working fluid such that the working fluid expands into a multi-phase mixture.

37. The heat transfer system of claim 36, wherein the heat exchanger comprises one or more of:(i) a rotary heat exchanger configured to cool the compressed working fluid; or(ii) a compression heat exchanger configured to remove heat from the working fluid during compression of the working fluid.

38. The heat transfer system of claim 36, wherein the heat transfer system is configured to operate on a transcritical cycle or a vapor compression cycle.

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