Description:FIELD OF THE INVENTION
The present invention relates generally to a low-speed radial turbine for Organic Rankine Cycle systems. More specifically present invention relates generally to a low-speed radial turbine with the bezier curve profile of the rotor blade (116) which is obtained by optimization of control points using the Taguchi method.
BACKGROUND OF THE INVENTION
The Organic Rankine Cycle (ORC) is a thermodynamic process designed to convert low-to-moderate temperature heat sources into usable mechanical and ultimately electrical energy. Unlike traditional steam Rankine cycles, the ORC utilizes organic working fluids with low boiling points, making it especially suitable for harvesting energy from low-grade heat sources such as geothermal reservoirs, industrial waste heat, biomass, and solar thermal collectors. A critical component of any ORC system is the expansion device typically a turbine which converts the energy stored in the pressurized vapor into rotational mechanical power. Among the expansion devices used, axial and radial turbines are the most common. However, when adapted for small- and medium-scale decentralized ORC systems, conventional turbine technologies reveal significant limitations that affect cost, reliability, efficiency, and integration. Axial turbines, while highly efficient at large scales, are optimized for high mass flow rates and high rotational speeds. These turbines usually require multi-stage arrangements to achieve desired performance levels, resulting in long axial footprints, complex fabrication processes, and increased tip leakage losses. Such configurations are ill-suited for compact ORC units or modular installations, where space, simplicity, and ease of maintenance are critical. Alternatively, radial turbines offer better geometrical compactness and are more adaptable to various ORC working fluids due to their favorable pressure-flow characteristics. However, most radial turbines in the art rely on reaction principles and necessitate extremely high rotational speeds often in excess of 20,000 RPM to achieve acceptable performance. These high speeds generate considerable mechanical stresses, raise the risk of component fatigue and failure, and increase dependency on expensive precision bearings and custom materials. Furthermore, high-speed turbines typically require downstream gearboxes or advanced power electronics to match generator speeds, thereby adding cost and reducing overall system reliability. Impulse turbines, which operate by directing high-velocity fluid jets through nozzles to strike rotor blades tangentially, present a promising alternative for ORC applications operating at low to moderate pressures. In impulse turbines, energy transfer is driven by momentum exchange rather than pressure gradients, thereby decoupling fluid pressure containment from rotating components. This leads to simplification in mechanical sealing, better tolerance for tip clearance losses, and easier integration into compact systems. Despite these advantages, existing impulse-type radial turbines exhibit critical design limitations that undermine their commercial utility in ORC systems. Firstly, the use of traditional blade profiles typically derived from circular arcs, splines, or empirical geometries results in abrupt changes in curvature that induce flow separation, turbulence, and shock losses during expansion. Secondly, many turbine designs allow sonic or even supersonic discharge velocities at the rotor outlet, leading to inefficient energy recovery and increased aerodynamic noise and vibration. Thirdly, most radial impulse turbines lack scalability; their designs are optimized around a fixed diameter or a single working fluid, thereby limiting their reusability or adaptability across different ORC platforms. Fourthly, the power density of small-scale turbines often depends on achieving extremely high RPMs, which exacerbates wear and compromises structural stability over time. Finally, the mechanical and electrical integration of prior art turbines often requires custom couplings, precision alignment procedures, and complex support structures, which increases installation costs and engineering overhead. These drawbacks have significantly constrained the deployment of efficient, compact, and affordable turbine technologies in decentralized ORC applications. In particular, sectors such as remote geothermal energy recovery, small-scale industrial cogeneration, containerized biomass plants, and off-grid solar-thermal ORC systems demand a turbine that can perform reliably under moderate thermodynamic conditions while offering ease of installation and long service life.
The present invention solves all the above drawbacks by introducing a novel radial turbine that redefines the performance, reliability, and versatility of expansion devices in ORC applications.
OBJECTIVE OF THE INVENTION
The main objective of the present invention is to provide a radial turbine comprising a rotor with blades defined by Bezier curve geometries, the blade geometry being optimized to minimize flow disturbances, reduce shock formation, and ensure subsonic fluid exit velocities from the impeller, thereby improving overall turbine efficiency.
Yet another objective of the present invention is to provide reduced maintenance and enhanced durability by enabling operation at low rotational speeds, typically between 3,000 and 9,000 RPM, thereby minimizing mechanical wear on bearings and rotating components.
Yet another objective of the present invention is to offer scalability across a wide range of rotor diameters while maintaining consistent thermodynamic performance, enabling versatile use in both small-scale and industrial-grade Organic Rankine Cycle (ORC) applications.
Yet another objective of the present invention is to facilitate cost-effective operation under moderate pressure and temperature conditions (15 bar and 125°C), eliminating the need for high-pressure vessels or exotic high-temperature materials.
Yet another objective of the present invention is to provide high power density per unit diameter, thereby enabling compact turbine designs that deliver substantial power output in limited spatial footprints.
Yet another objective of the present invention is to achieve efficient fluid utilization with optimized power-to-mass flow ratios, allowing for reduced fluid inventory and smaller auxiliary components such as pumps and piping.
Yet another objective of the present invention is to support the dual working fluid compatibility, including R245fa and R134a, thereby offering flexibility for deployment across various heat source profiles and ORC configurations.
Yet another objective of the present invention is to simplify system integration by operating within standard ORC input parameters, enabling seamless coupling with conventional heat exchangers, generators, and control systems.
Yet another objective of the present invention is to exhibit broad applicability to abundant low-grade thermal energy sources, including industrial waste heat, geothermal sources, and solar thermal inputs, thereby enabling sustainable power generation in decentralized environments.
Further objectives, advantages, and features of the present invention will become apparent from the detailed description provided herein below, in which various embodiments of the disclosed invention are illustrated by way of example.
SUMMARY OF THE INVENTION
The present invention relates to a radial turbine for Organic Rankine Cycle systems. The present invention includes a backplate, a rotor assembly, a casing and nozzle. The backplate is a primary circular plate and serves as the main structural element of the turbine. The backplate includes a shaft, mechanical seal, axial thrust bearing and radial thrust bearing. The shaft is a cylindrical component which transmits rotational energy. The mechanical seal which is located at the interface between the shaft and the backplate prevents leakage of process fluid along the rotating shaft ensuring a hermetic seal under operational pressures and temperatures essential for maintaining the integrity of the turbine. The axial thrust bearing is used to handle forces parallel to the axis of the shaft and thrust preventing axial movement of the shaft which ensures the rotor assembly remains securely positioned during operation. The radial thrust bearing manages radial forces perpendicular to the axis of the shaft distributed around the shaft within the backplate providing uniform radial support to the shaft minimizing lateral deflection and ensuring stable rotation which is critical for maintaining alignment and reducing wear. The backplate is used to facilitate a smooth power transfer from the turbine to the generator. The shaft is provided with precise dimensional tolerances to maintain alignment. The rotor assembly which is the central rotating part of the turbine includes rotor blade, a central hub. In this turbine, the rotor blade is configured to convert the kinetic energy of high velocity working fluid jets discharged from the nozzles into rotational energy of the rotor assembly, while permitting an additional pressure drop across the rotor to improve overall turbine efficiency. The central hub which is at the centre of the backplate serves as the mounting point for the shaft, the axial thrust bearing and the radial thrust bearing and providing a stable interface for connecting the generator. The axial thrust bearing and the radial thrust bearing absorb the axial loads and the radial loads respectively generated by the weight of the rotor assembly. The casing comprises an inlet section, a tapered midsection, an outlet section, and a casing wall. The inlet section is configured to connect to a fluid supply and is shaped to maintain the required inlet pressure while minimizing turbulence, thereby ensuring smooth and stable fluid entry. The tapered midsection gradually reduces in diameter from the inlet toward the rotor entry zone, facilitating acceleration of the working fluid, suppressing turbulence, preventing flow separation or backflow, and promoting rapid and directed flow toward the rotor blades. The outlet section is dimensioned with an inner diameter optimized to permit the expanded, low-pressure working fluid to exit the turbine in a subsonic regime, thereby ensuring efficient pressure recovery and stable downstream flow. The casing wall having uniform thickness and a round design to makes sure that the stress is distributed out evenly and to provide structural integrity under heat stress and dynamic loading. The nozzle is symmetrically placed around the rotor assembly and used to direct high-velocity fluid jets tangentially toward the rotor blade at an angle of approximately 67° making the process of imparting torque to the rotor assembly easier. The rotor blade is twisted along its length and is spline-defined to distribute stress uniformly and guide the working fluid progressively from leading edge to trailing edge. The profile of the rotor blade is defined by a smooth shape which is a function of a Bezier curve allowing great and vast freedom in shaping the flow path, ensuring subsonic outlet flow and improving aerodynamic and structural efficiency of the turbine.
The main advantage of the present invention is that the present invention provides a radial inflow turbine featuring rotor blades designed with Bezier curve profiles, enabling smooth, continuous curvature and precise control over blade geometry. This advanced blade shaping promotes shockless fluid flow with minimal abrupt directional changes, significantly reducing secondary flow effects and associated energy losses. As a result, the aerodynamic efficiency of the turbine is substantially enhanced. Importantly, the working fluid is configured to exit the impeller at subsonic velocity, which yields several critical advantages: it ensures efficient conversion of kinetic energy into shaft power, avoids the formation of shock waves that typically occur with supersonic flow, and maintains stable, predictable flow characteristics. Moreover, subsonic exhaust facilitates improved pressure recovery in downstream components such as diffusers, volutes, or condensers, while also minimizing aerodynamic noise, mechanical stress, and vibration. These factors collectively contribute to enhanced turbine performance, reduced maintenance requirements, and extended operational lifespan.
Yet another advantage of the present invention is that the present invention provides reduced maintenance and enhanced durability by enabling operation at low rotational speeds, typically between 3,000 and 9,000 RPM, thereby minimizing mechanical wear on bearings and rotating components.
Yet another advantage of the present invention is that the present invention offers scalability across a wide range of rotor diameters while maintaining consistent thermodynamic performance, enabling versatile use in both small-scale and industrial-grade Organic Rankine Cycle (ORC) applications.
Yet another advantage of the present invention is that the present invention facilitates cost-effective operation under moderate pressure and temperature conditions (15 bar and 125°C), eliminating the need for high-pressure vessels or exotic high-temperature materials.
Yet another advantage of the present invention is that it delivers high power density per unit turbine diameter, enabling the development of compact turbine designs capable of producing substantial power output while minimizing overall system size and footprint.
Yet another advantage of the present invention is that it achieves efficient utilization of the working fluid by optimizing the power-to-mass flow rate ratio, thereby enabling reduced fluid inventory requirements and downsizing of auxiliary components such as pumps and piping.
Yet another advantage of the present invention is that the present invention supports dual working fluid compatibility, including R245fa and R134a, thereby offering flexibility for deployment across various heat source profiles and ORC configurations.
Yet another advantage of the present invention is that the present invention simplifies system integration by operating within standard ORC input parameters.
Yet another advantage of the present invention is that the present invention exhibits broad applicability to abundant low-grade thermal energy sources, including industrial waste heat, geothermal sources, and solar thermal inputs, thereby enabling sustainable power generation in decentralized environments.
Further objectives, advantages, and features of the present invention will become apparent from the detailed description provided herein below, in which various embodiments of the disclosed invention are illustrated by way of example.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are incorporated in and constitute a part of this specification to provide a further understanding of the invention. The drawings illustrate one embodiment of the invention and together with the description, serve to explain the principles of the invention.
Fig.1 illustrates the overview of the radial turbine for Organic Rankine Cycle systems.
Fig.2 illustrates optimization of control points on the rotor blades of turbine using the Taguchi method.
Fig.3 illustrates velocity distribution of fluid along spanwise in in rotor assembly.
Fig.4 illustrates velocity distribution of fluid at outlet.
Fig.5 illustrates absolute pressure distribution of fluid along spanwise in rotor assembly.
Fig.6 illustrates variation of density of flowing fluid along spanwise in rotor assembly.
Fig.7 illustrates variation of temperature of flowing fluid along spanwise in rotor assembly.
Fig.8 and Fig.9 illustrates comparison table of different existing turbines with the results of present invention.
DETAILED DESCRIPTION OF THE INVENTION
Definition
The terms “a” or “an”, as used herein, are defined as one or as more than one. The term “plurality”, as used herein, is defined as two as or more than two. The term “another”, as used herein, is defined as at least a second or more. The terms “including” and/or “having”, as used herein, are defined as comprising (i.e., open language). The term “coupled”, as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically.
The term “comprising” is not intended to limit inventions to only claiming the present invention with such comprising language. Any invention using the term comprising could be separated into one or more claims using “consisting of” or “consisting of” claim language and is so intended. The term “comprising” is used interchangeably used by the terms “having” or “containing”.
Reference throughout this document to “one embodiment”, “certain embodiments”, “an embodiment”, “another embodiment”, and “yet another embodiment” or similar terms means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of such phrases or in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics are combined in any suitable manner in one or more embodiments without limitation.
The term “or” as used herein is to be interpreted as an inclusive or meaning any one or any combination. Therefore, “A, B or C” means any of the following: “A; B; C; A and B; A and C; B and C; A, B and C”. An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive.
As used herein, the term "one or more" generally refers to, but not limited to, singular as well as the plural form of the term.
The drawings featured in the figures are to illustrate certain convenient embodiments of the present invention and are not to be considered as a limitation to that. The term "means" preceding a present participle of an operation indicates the desired function for which there is one or more embodiments, i.e., one or more methods, devices, or apparatuses for achieving the desired function and that one skilled in the art could select from these or their equivalent in view of the disclosure herein and use of the term "means" is not intended to be limiting.
Fig.1 illustrates the overview of the low-speed radial turbine (100) for Organic Rankine Cycle systems. The present invention includes a backplate (104), a rotor assembly (114), a casing (118) and nozzle (128). The backplate (104) is a primary circular plate and serves as the main structural element of the turbine (100). The backplate (104) includes a shaft (102), mechanical seal (106), axial thrust bearing (108) and radial thrust bearing (110). The rotor assembly (114) which is the central rotating part of the turbine (100) includes a rotor blade (116) and a central hub (112). The casing (120) includes an inlet section (120), a tapered midsection (122), outlet section (124) and a casing wall (126).
Fig. 2 illustrates the optimization of control points using the Taguchi method. The Bezier curve of the rotor blade (116) is generated by optimizing the control points selected along the profile of the rotor blade (116), resulting in 81 possible design permutations. This approach provides significant flexibility in shaping the rotor blade (116), which is critical for minimizing flow disturbances and enhancing aerodynamic efficiency. The use of Bezier curves ensures a smooth and continuous fluid path, thereby reducing the likelihood of shock formation. As a result, the fluid flow through the rotor assembly (114) remains largely shockless, and the working fluid exits the rotor assembly (114 at subsonic velocity, contributing to improved performance of turbine (100).
Fig.3 illustrates velocity distribution of fluid along spanwise in in rotor assembly (114). The velocity magnitude distribution within the rotor assembly (114) shows peak velocities concentrated near the tips of the rotor blade (116) and shroud region, a direct result of the combination of nozzle-directed flow toward the outer radius and the increased circumferential speed imparted by the rotor blade (116). This acceleration pattern reflects efficient energy transfer from the high-velocity jets to the rotor assembly (114), where the flow is guided and accelerated along the passages of the rotor blade (116) toward the outlet.
Fig.4 illustrates velocity distribution of fluid at outlet. At the outlet the velocity field exhibits a more developed and directional pattern, indicating that the kinetic energy imparted within the rotor assembly (114) is being converted into a controlled discharge jet for downstream utilization. This phenomenon signifies effective momentum exchange and confirms that the geometry of the rotor assembly (114) and the alignment of nozzle (128) are producing a strong, targeted outflow, directly affecting power output and overall aerodynamic efficiency of turbine (100).
Fig.5 illustrates absolute pressure distribution of fluid along spanwise in rotor assembly (114). The absolute pressure distribution in the rotor assembly (114) reveals that there are high-pressure regions along the leading edges at the outer radius. This means that energy is effectively transferred from the incoming flow to the rotor blade (116) by impact and rotating. The gradual drop in pressure toward the outlet region in the channels of the rotor assembly (114) indicates regulated expansion and acceleration, resulting in it possible to efficiently convert pressure energy into kinetic energy. The more uniform and lower-pressure profile at the output is beneficial because it makes the flow into the downstream components smoother, which lowers the possibility of flow separation and increases the overall efficiency of the stage. This pattern of pressure shows that the shape of the rotor assembly (114) successfully captures energy from the intake, generates a strong driving torque, and makes sure that the flow is well-conditioned for the optimal performance of the turbine (100).
Fig.6 illustrates variation of density of flowing fluid along spanwise in rotor assembly (114). The density distribution inside the rotor assembly (114) indicates greater fluid density regions near the leading edges at the outer radius, progressively declining toward the trailing edges, signifying regulated expansion of the working fluid between the rotor blade (116). This expansion transforms pressure energy into mechanical energy while ensuring stable acceleration, enabling effective momentum transfer to the rotor assembly (114). The design of the rotor assembly (114), characterized by curved geometry of rotor blade (116) and outward flow path, promotes consistent radial expansion and optimizes the use of the available enthalpy drop, resulting in greater torque production. The lower and more uniform density profile at the output enhances downstream flow compatibility, reduces losses, and promotes greater stage efficiency. This distribution pattern illustrates the capacity of rotor assembly (114) for efficient energy conversion within a compact design, optimizing both power production and operational efficiency under the specified parameters.
Fig.7 illustrates variation of temperature of flowing fluid along spanwise in rotor assembly (114). The temperature contour through shows that as the working fluid enters the rotor assembly (114) at the leading edge, the working fluid has a relatively higher static temperature (around 124-125 °C), and as it flows radially outward between the rotor blade (116), the working fluid undergoes expansion. This expansion within the passages of rotor blade (116) causes the fluid’s static temperature to drop progressively toward the trailing edge and outlet, as seen in the cooler side. The radial-type design of the rotor assembly (114) allows the fluid to expand efficiently in a controlled manner along the increasing flow area between the rotor blade (116), which maximizes the conversion of thermal energy into mechanical energy before it exits. This temperature gradient indicates effective energy extraction, as the reduction in static temperature corresponds to an increase in velocity and mechanical power output. The strong radial acceleration of the geometry permits the rotor assembly (114) to get energy uniformly, that enhances performance and maintains the operation effortlessly while also allows for a compact design with high specific power.
Fig.8 and Fig.9 illustrates comparison table of different existing turbines with the results of present invention. The turbine (100) has certain scales of advantage over other radial inflow turbines mentioned in the literature, particularly those related to scalability and performance parameters, viz, power per unit mass flow rate, power per unit diameter, and power per unit inlet pressure, which can assure a better, compact, and versatile organic Rankine cycle (ORC) application. For R245fa configurations, the turbine (100) consistently achieves a high power per unit mass flow rate of around 26 kW/(kg/s), outperforming the average of approximately 18 kW/(kg/s) across comparable studies, which allows for greater power generation with less working fluid, reducing pumping energy, system complexity, and operational costs. The power per unit diameter of turbine (100) averages 0.4 kW/mm with peaks up to 0.81 kW/mm in smaller, higher-RPM variants surpassing the literature average of about 0.31 kW/mm, facilitating more compact designs that are ideal for space-limited installations while maintaining or exceeding power output. In addition, the turbine (100) power per unit inlet pressure is 10.47 kW/bar in its 157 kW arrangements (an average of 6.2 kW/Bar overall), which is much higher compared to the usual 2-3 kW/bar on other turbines. This allows for the extraction of higher power at moderate pressures, thereby increasing levels of safety, durability of materials, and suitability in implementing low-grade heat sources. For R134a, while the power per unit mass flow opportunity is still competitive at 12.44 kW/(kg/ s) in respect to an average of 19 kW/(kg/s), the strength of the turbine (100) lies in having a very small compactness in terms of the average power per unit diameter of 0.27 kW/mm (over 0.22 kW/mm in the others) and consistent power per unit inlet pressure of 3.33 kW/Bar (slightly above a 2.86 kW/Bar average), indicating real potential benefits in the scalable, low-RPM operation for different fluids and conditions vis-à-vis the less-flexible literature designs. A thorough numerical analysis was carried out in this radial-type turbine (100) using ANSYS Fluent. All boundary conditions were peculiar to any turbulence or fluid problem, i.e., inlet pressure, temperature, mass flow rate, and outlet pressure were accurately assigned to the computational domain so as to simulate the actual operating conditions. The simulation was considered under steady-state conditions, wherein the focus rested upon resolving the flow field and reproducing the thermodynamic and aerodynamic behaviour of the working fluid as it flowed through the passages of the rotor assembly (114). At the conclusion of the computation, the solver generated the detailed results of the static temperature distribution, velocity, density, and pressure variations within the domain of the rotor assembly (114). These results were then rigorously analyzed to determine flow patterns, energy conversion, and evaluate the thermal and mechanical performances of the impeller geometry. Following which, based on the exhaustive analysis, a set of results are established. Such an approach ensures that the results obtained were scientifically valid and representative of the actual, experimental operating characteristics of the turbine. Based on these analyses, the rotor assembly (114) operates effectively under real-world boundary conditions. The analytical study presented in the Table as shown in the figure shows that, when compared to other turbine configurations, the design of the turbine (100) performs exceptionally well in velocity management, pressure recovery, density regulation, and temperature drop, all of which directly contribute to higher torque and efficiency. The CFD results not only confirm the design’s performance but also validate aerodynamic and thermodynamic behaviour of the turbine (100) against realistic boundary conditions, ensuring that the claimed advantages are supported by rigorous simulation data.
The present invention relates to a low-speed radial turbine for Organic Rankine Cycle systems. The present invention includes a backplate, a rotor assembly, a casing and nozzle. The backplate is a primary circular plate and serves as the main structural element of the turbine. The backplate includes a shaft, mechanical seal, axial thrust bearing and radial thrust bearing. The shaft is a cylindrical component which transmits rotational energy. The mechanical seal which is located at the interface between the shaft and the backplate prevents leakage of process fluid along the rotating shaft ensuring a hermetic seal under operational pressures and temperatures essential for maintaining the integrity of the turbine. The axial thrust bearing is used to handle forces parallel to the axis of the shaft and thrust preventing axial movement of the shaft which ensures that the rotor assembly remains securely positioned during operation. The radial thrust bearing manages radial forces perpendicular to the axis of the shaft distributed around the shaft within the backplate providing uniform radial support to the shaft minimizing lateral deflection and ensuring stable rotation which is critical for maintaining alignment and reducing wear. The backplate is used to facilitate a smooth power transfer from the turbine to the generator. In an embodiment, the backplate is made of stainless steel which provides corrosion resistance and durability under the demanding conditions of the turbine. The shaft is provided with precise dimensional tolerances to maintain alignment. The rotor assembly which is the central rotating part of the turbine includes rotor blade and a central hub. The rotor blade is used to convert the kinetic energy of the fast-moving fluid into rotational energy of the rotor assembly. The central hub which is at the centre of the backplate serves as the mounting point for the shaft, the axial thrust bearing, and the radial thrust bearing and providing a stable interface for connecting the generator. The axial thrust bearing, and the radial thrust bearing absorb the axial loads and the radial loads respectively generated by the weight of the rotor assembly. The casing comprises an inlet section, a tapered midsection, an outlet section, and a surrounding casing wall. The inlet section is configured to connect to a fluid supply and is shaped to maintain inlet pressure while minimizing turbulence, thereby ensuring smooth fluid entry. The tapered midsection gradually reduces in diameter from the inlet section toward the rotor entry zone, facilitating acceleration of the working fluid, reducing turbulence, and preventing flow separation or backflow. This geometry ensures efficient delivery of the fluid to the rotor blade. The outlet section is designed with an inner diameter sufficient to accommodate the expanded, low-pressure working fluid and enables subsonic discharge, promoting stable downstream flow and efficient pressure recovery. The casing wall having uniform thickness and a round design to make sure that the stress is distributed out evenly and to provide structural integrity under heat stress and dynamic loading. The nozzle is symmetrically placed around the rotor assembly and used to direct high-velocity fluid jets tangentially toward the rotor blade at an angle of approximately 67° making the process of imparting torque to the rotor assembly easier. In an embodiment, turbine is configured to operate at low rotational speeds between 3,000 to 9,000 RPM which increases operating longevity by reducing mechanical stress over the internal components of the turbine. In an embodiment, the turbine operates at moderate thermodynamic input conditions of 15 bar pressure and 125°C temperature eliminating the need for high-pressure containers or specific high-temperature materials minimizing the material costs and enabling reliable and cost-effective integration into Organic Rankine Cycle (ORC) systems. In an embodiment, the turbine is provided with mechanical support legs and is designed to absorb vibrations, carry axial and radial thrust loads and keep the turbine in line and structurally sound. In an embodiment, the turbine employs moderate mass flow rates ranging from 1.92 to 6.01 kg/s for R245fa and 4.018 kg/s for R134a to produce a high power-to-mass flow ratio of up to 26.12 kW/(kg/s). In an embodiment, turbine provides high power density allowing compact designs to deliver substantial power addressing the low power density issue of small turbines. In an embodiment, the turbine uses either R245fa or R134a demonstrating that the design of the turbine is flexible enough to accommodate both fluids making the turbine usable in many ORC setups such as regular waste heat recovery (R245fa) and low-temperature applications like OTEC (R134a). The rotor blade is twisted along its length and is spline-defined to distribute stress uniformly and guide the working fluid progressively from leading edge to trailing edge. The profile of the rotor blade is defined by a smooth geometry constructed using a Bezier curve, offering substantial flexibility in shaping the flow path and enabling continuous, curvature-controlled transitions from leading edge to trailing edge. This smooth profile, free of sharp bends or discontinuities, minimizes turbulence, suppresses flow separation, and eliminates stress concentrations resulted enhancing aerodynamic performance, improving fatigue resistance, and extending life of rotor blade under high rotational stresses. The Bezier curve profile is derived by optimizing control points along the blade using the Taguchi method, resulting in 81 design permutations that allow precise tuning of geometry of rotor blade to match specific operating conditions. The hub-side and shroud-side profiles are individually optimized through this method to reduce shock losses and promote smoother downstream flow. This configuration ensures subsonic outlet flow across all operating regimes, leading to improved energy recovery by enabling more efficient conversion of kinetic energy into shaft power, avoiding shock-induced energy losses, stabilizing the flow field, and supporting effective diffusion and pressure recovery. Additionally, the subsonic outlet minimizes aerodynamic noise and mechanical vibration. Approximately after 80% of the fluid path along the rotor blade span, the rotor blade is twisted to 35° to ensure optimal flow alignment, minimize incidence losses, and uniformly distribute aerodynamic and mechanical stresses. This enhances both aerodynamic efficiency and structural integrity of the rotor blade. Collectively, these features contribute to improved reliability, longer operational life, and enhanced overall system efficiency—particularly beneficial for applications such as Organic Rankine Cycle (ORC) systems.
In an embodiment, the present invention relates to a low-speed radial turbine for Organic Rankine Cycle systems. The present invention includes a backplate, a rotor assembly, a casing and one or more nozzles. The backplate is a primary circular plate and serves as the main structural element of the turbine. The backplate includes a shaft, mechanical seal, one or more axial thrust bearings and one or more radial thrust bearings. The shaft is a cylindrical component which transmits rotational energy. The mechanical seal which is located at the interface between the shaft and the backplate prevents leakage of process fluid along the rotating shaft ensuring a hermetic seal under operational pressures and temperatures essential for maintaining the integrity of the turbine. The one or more axial thrust bearings are used to handle forces parallel to the axis of the shaft and thrust preventing axial movement of the shaft which ensures the rotor assembly remains securely positioned during operation. The one or more radial thrust bearings manage radial forces perpendicular to the axis of the shaft distributed around the shaft within the backplate providing uniform radial support to the shaft minimizing lateral deflection and ensuring stable rotation which is critical for maintaining alignment and reducing wear. The backplate is used to facilitate a smooth power transfer from the turbine to the generator. In an embodiment, the backplate is made of stainless steel which provides corrosion resistance and durability under the demanding conditions of the turbine. The shaft is provided with precise dimensional tolerances to maintain alignment. The rotor assembly which is the central rotating part of the turbine includes one or more rotor blades and a central hub. The one or more rotor blades are used to convert the kinetic energy of the fast-moving fluid into rotational energy of the rotor assembly. The central hub which is at the centre of the backplate serves as the mounting point for the shaft, the one or more axial thrust bearings and the one or more radial thrust bearings and providing a stable interface for connecting the generator. The one or more axial thrust bearings and the one or more radial thrust bearings absorb the axial loads and the radial loads respectively generated by the weight of the rotor assembly. The casing of the radial turbine is designed to guide the working fluid efficiently through three integrated sections: an inlet section, a tapered midsection, and an outlet section, all enclosed within a continuous casing wall. The inlet section is shaped to smoothly connect with the fluid supply line and is specifically contoured to maintain the required inlet pressure while minimizing flow turbulence and separation, thereby ensuring stable and efficient fluid entry into the turbine. As the fluid progresses through the casing, it encounters the tapered midsection, which gradually decreases in diameter toward the rotor assembly. This reduction in cross-sectional area causes the fluid velocity to increase due to the conservation of mass and energy, effectively accelerating the flow while further reducing turbulence and the risk of backflow. This geometric transition also helps to ensure that the working fluid reaches the rotor blades with sufficient kinetic energy for optimal energy transfer. The flow is then directed toward the outlet section, which is configured with an inner diameter sized to permit the expanded, low-pressure fluid to exit the casing at subsonic speeds. Maintaining subsonic exit flow is critical to prevent the formation of shock waves, reduce noise and mechanical vibration, and enhance the downstream pressure recovery process particularly important in systems requiring high thermodynamic efficiency, such as Organic Rankine Cycle (ORC) applications. This integrated casing geometry, through its careful design of pressure preservation, acceleration, and controlled expansion, enables improved overall turbine performance, reduced aerodynamic losses, and enhanced operational reliability. The casing wall having uniform thickness and a round design to makes sure that the stress is distributed out evenly and to provide structural integrity under heat stress and dynamic loading. The one or more nozzles are symmetrically placed around the rotor assembly and used to direct high-velocity fluid jets tangentially toward the one or more rotor blades at an angle of approximately 67° making the process of imparting torque to the rotor assembly easier. In an embodiment, turbine is configured to operate at low rotational speeds between 3,000 to 9,000 RPM which increases operating longevity by reducing mechanical stress over the internal components of the turbine. In an embodiment, the turbine operates at moderate thermodynamic input conditions of 15 bar pressure and 125°C temperature eliminating the need for high-pressure containers or specific high-temperature materials minimizing the material costs and enabling reliable and cost-effective integration into Organic Rankine Cycle (ORC) systems. In an embodiment, the turbine is provided with mechanical support legs and is designed to absorb vibrations, carry axial and radial thrust loads and keep the turbine in line and structurally sound. In an embodiment, the turbine employs moderate mass flow rates ranging from 1.92 to 6.01 kg/s for R245fa and 4.018 kg/s for R134a to produce a high power-to-mass flow ratio of up to 26.123 kW/(kg/s). In an embodiment, turbine provides high power density allowing compact designs to deliver substantial power addressing the low power density issue of small turbines. In an embodiment, the turbine uses either R245fa or R134a demonstrating that the design of the turbine is flexible enough to accommodate both fluids making the turbine usable in many ORC setups such as regular waste heat recovery (R245fa) and low-temperature applications like OTEC (R134a). The one or more rotor blades are twisted along its length and is spline-defined to distribute stress uniformly and guide the working fluid progressively from leading edge to trailing edge. The profile of the one or more rotor blades is defined by a smooth geometry constructed using a Bezier curve, offering substantial flexibility in shaping the flow path and enabling continuous, curvature-controlled transitions from leading edge to trailing edge. This smooth profile, free of sharp bends or discontinuities, minimizes turbulence, suppresses flow separation, and eliminates stress concentrations resulted enhancing aerodynamic performance, improving fatigue resistance, and extending blade life under high rotational stresses. The Bezier curve profile is derived by optimizing control points along the blade using the Taguchi method, resulting in 81 design permutations that allow precise tuning of geometry of one or more blades to match specific operating conditions. The hub-side and shroud-side profiles are individually optimized through this method to reduce shock losses and promote smoother downstream flow. This configuration ensures subsonic outlet flow across all operating regimes, leading to improved energy recovery by enabling more efficient conversion of kinetic energy into shaft power, avoiding shock-induced energy losses, stabilizing the flow field, and supporting effective diffusion and pressure recovery. Additionally, the subsonic outlet minimizes aerodynamic noise and mechanical vibration. Approximately after 80% of the fluid path along the span of the one or more rotor blades, the one or more rotor blades are twisted to 35° to ensure optimal flow alignment, minimize incidence losses, and uniformly distribute aerodynamic and mechanical stresses. This enhances both aerodynamic efficiency and structural integrity of the one or more rotor blade. Collectively, these features contribute to improved reliability, longer operational life, and enhanced overall system efficiency particularly beneficial for applications such as Organic Rankine Cycle (ORC) systems. In an embodiment, the Bezier curve profile of the one or more rotor blades guarantees a blade profile that is both continuous and smooth without any sharp bending in curvature, thereby greatly reducing turbulence, tendency toward flow separation which enhances aerodynamic performance by minimizing energy loss and drag, maximizes fluid guidance through the rotor assembly for energy extraction and removes stress concentrations by relieving the profile of the one or more rotor blades of any sharp edge or discontinuity which results in an increase in structural integrity, fatigue resistance, and life of the one or more rotor blades under high rotational stresses.
In an embodiment, the present invention relates to a method for operating the radial turbine, the method includes:
the manifold delivers high-temperature, high-pressure working fluid to the nozzle;
a substantial portion of the enthalpy drop is converted into kinetic energy to produce a high-momentum jet directed toward the leading edges of the rotating rotor blade;
the incoming jet exhibits a relative velocity vector that is redirected within the passages of the rotor blade, thereby generating tangential forces on the rotor assembly to produce torque;
as the fluid progresses from the leading edge to the trailing edge, centrifugal forces and radial pressure gradients induced by rotation of the rotor blade causes density and pressure variations, while expansion within the channels of the rotor blade further augments torque generation;
the coordinated conversion of kinetic and potential energy into mechanical power enables a compact, high-performance turbine configuration;
static pressure is discharged into the outlet annulus upon exiting the trailing edge of the rotor blade.
In an embodiment, the present invention relates to a method for operating the radial turbine, the method includes:
the manifold delivers high-temperature, high-pressure working fluid to the one or more nozzles;
a substantial portion of the enthalpy drop is converted into kinetic energy to produce a high-momentum jet directed toward the leading edges of the rotating one or more rotor blades;
the incoming jet exhibits a relative velocity vector that is redirected within the passages of the one or more rotor blades, thereby generating tangential forces on the rotor assembly to produce torque;
as the fluid progresses from the leading edge to the trailing edge, centrifugal forces and radial pressure gradients induced by rotation of the one or more rotor blades cause density and pressure variations, while expansion within the channels of the one or more rotor blades further augment torque generation;
the coordinated conversion of kinetic and potential energy into mechanical power enables a compact, high-performance turbine configuration;
static pressure is discharged into the outlet annulus upon exiting the trailing edge of the one or more rotor blades. , Claims:I/WE CLAIM
1. A low speed radial turbine (100) for Organic Rankine Cycle systems, the turbine (100) comprising:
a backplate (104), the backplate (104) is a primary circular plate and serves as the main structural element of the turbine (100), the backplate (104) having
a shaft (102), the shaft (102) is a cylindrical component which transmits rotational energy,
a mechanical seal (106), the mechanical seal (106) is located at the interface between the shaft (102) and the backplate (104), the mechanical seal (106) prevents leakage of process fluid along the rotating shaft (102) ensuring a hermetic seal under operational pressures and temperatures essential for maintaining the integrity of the turbine (100),
an at least one axial thrust bearing (108), the at least one axial thrust bearing (108) is used to handle forces parallel to the axis of the shaft (102) and thrust preventing axial movement of the shaft (100) which ensures the rotor assembly (114) remains securely positioned during operation, and
an at least one radial thrust bearing (110), the at least one radial thrust bearing (110) manage radial forces perpendicular to the axis of the shaft (102) distributed around the shaft (102) within the backplate (104) providing uniform radial support to the shaft (102) minimizing lateral deflection and ensuring stable rotation which is critical for maintaining alignment and reducing wear;
wherein, the backplate (104) is used to facilitate a smooth power transfer from the turbine (100) to the generator,
wherein, the shaft (102) is provided with precise dimensional tolerances to maintain alignment,

a rotor assembly (114), the rotor assembly (114) is the central rotating part of the turbine (100), the rotor assembly (114) having
an at least one rotor blade (116), the at least one rotor blade (116) is used to convert the kinetic energy of the fast-moving fluid into rotational energy of the rotor assembly (114), and
a central hub (112), the central hub (112) is at the centre of the backplate (104), the central hub (112) serves as the mounting point for the shaft (102), the at least one axial thrust bearing (108) and the at least one radial thrust bearing (110) and providing a stable interface for connecting the generator;
wherein, the at least one axial thrust bearing (108) and the at least one radial thrust bearing (110) absorb the axial loads and the radial loads respectively generated by the weight of the rotor assembly (114),
a casing (118), the casing (118) having
an inlet section (120), the inlet section (120) being connected to a fluid supply and shaped to maintain inlet pressure and minimize turbulence to ensure smooth fluid entry;
a tapered midsection (122), the tapered midsection (122) reducing in diameter from the inlet section (120) to the entry zone of the rotor assembly (114) to accelerate the working fluid flow, lower turbulence, prevent backflow and ensuring efficient delivery of the fluid to the at least one rotor blade (116),
an outlet section (124), the outlet section (124) is configured with an inner diameter sufficient to accommodate the expanded, low-pressure working fluid and enables subsonic discharge, promoting stable downstream flow and efficient pressure recovery, and
a casing wall (126), the casing wall (126) having uniform thickness and a round design to makes sure that the stress is distributed out evenly and to provide structural integrity under heat stress and dynamic loading;
an at least one nozzle (128), the at least one nozzle (128) is symmetrically placed around the rotor assembly (114) and used to direct high-velocity fluid jets tangentially toward the at least one rotor blade (116) at an angle of approximately 67° making the process of imparting torque to the rotor assembly (114) easier;
wherein, the at least one rotor blade (116) is twisted along its length and is spline-defined to distribute stress uniformly and guide the working fluid progressively from leading edge to trailing edge,
wherein, approximately after 80% of the fluid path along the at least one rotor blade (116) span, the at least one rotor blade (116) is twisted to 35° to ensure optimal flow alignment, minimize incidence losses, and uniformly distribute aerodynamic and mechanical stresses which enhances both aerodynamic efficiency and structural integrity of the at least one rotor blade (116),
wherein, the profile of the at least one rotor blade (116) is defined by a smooth shape which is a function of a Bezier curve allowing great and vast freedom in shaping the flow path, ensuring subsonic outlet flow and improving aerodynamic and structural efficiency of the turbine (100),
characterize in that, the Bezier curve profile of the at least one rotor blade (116) is obtained by optimization of control points selected on the profile of the at least one rotor blade (116) using the Taguchi method and producing 81 possible design permutations which allows the profile of the at least one rotor blade (116) a great deal of flexibility which is paramount to minimizing flow disturbances and attaining aerodynamic efficiency,
characterize in that, the Bezier curve profile of the at least one rotor blade (116) which is obtained by optimization of control points selected on the profile of the at least one rotor blade (116) using the Taguchi method enables precise control over the geometry of the at least one rotor blade (116) to ensure subsonic flow conditions at the outlet of the rotor assembly (114) across all operating conditions, thus ensuring reduced aerodynamic noise and mechanical vibrations resulting in improved reliability and operational stability of the turbine (100) across all operating conditions of the turbine (100),
characterize in that, the hub-side profile and shroud-side profile of the at least one rotor blade (116) are each defined by distinct Bezier curves which are individually optimized by adjusting their control points using the Taguchi method and which minimizes shock losses and simplifies the design of downstream components reducing aerodynamic noise and mechanical vibrations, resulting in improved reliability and operational stability of the turbine thereby enhancing overall system efficiency which is an essential requirement in applications such as Organic Rankine Cycle (ORC) systems.
2. The radial turbine (100) as claimed in claim 1, wherein the Bezier curve profile of the at least one rotor blade (116) guarantees a blade profile that is both continuous and smooth without any sharp bending in curvature, thereby greatly reducing turbulence, tendency toward flow separation which enhances aerodynamic performance by minimizing energy loss and drag, maximizes fluid guidance through the rotor assembly (114) for energy extraction and removes stress concentrations by relieving the profile of the at least one rotor blade (116) of any sharp edge or discontinuity which results in an increase in structural integrity, fatigue resistance, and life of the at least one rotor blade (116) under high rotational stresses.
3. The radial turbine (100) as claimed in claim 1, wherein the turbine (100) operates at moderate thermodynamic input conditions of 15 bar pressure and 125°C temperature eliminating the need for high-pressure containers or specific high-temperature materials minimizing the material costs and enabling reliable and cost-effective integration into Organic Rankine Cycle (ORC) systems.
4. The radial turbine (100) as claimed in claim 1, wherein the turbine (100) is configured to operate at low rotational speeds between 3,000 to 9,000 RPM which increases operating longevity by reducing mechanical stress over the internal components of the turbine (100).
5. The radial turbine (100) as claimed in claim 1, wherein the backplate (104) is made of stainless steel which provides corrosion resistance and durability under the demanding conditions of the turbine (100).
6. The radial turbine (100) as claimed in claim 1, wherein the turbine (100) is provided with mechanical support legs and is designed to absorb vibrations, carry axial and radial thrust loads and keep the turbine (100) in line and structurally sound.
7. The radial turbine (100) as claimed in claim 1, wherein the turbine (100) employs moderate mass flow rates ranging from 1.92 to 6.01 kg/s for R245fa and 4.018 kg/s for R134a to produce a high power-to-mass flow ratio of up to 26.123 kW/(kg/s).
8. The radial turbine (100) as claimed in claim 1, wherein turbine (100) provides high power density allowing compact designs to deliver substantial power addressing the low power density issue of small turbines.
9. The radial turbine (100) as claimed in claim 1, wherein the turbine (100) uses either R245fa or R134a demonstrating that the design of the turbine (100) is flexible enough to accommodate both fluids making the turbine (100) usable in many ORC setups such as regular waste heat recovery (R245fa) and low-temperature applications like OTEC (R134a).
10. A method for operating the radial turbine (100) as claimed in claim 1, the method comprising:
the manifold delivers high-temperature, high-pressure working fluid to the at least one nozzle (128);
a substantial portion of the enthalpy drop is converted into kinetic energy to produce a high-momentum jet directed toward the leading edges of the rotating at least one rotor blade (116);
the incoming jet exhibits a relative velocity vector that is redirected within the passages of the at least one rotor blade (116), thereby generating tangential forces on the rotor assembly (114) to produce torque;
as the fluid progresses from the leading edge to the trailing edge, centrifugal forces and radial pressure gradients induced by rotation of the at least one rotor blade (116) causes density and pressure variations, while expansion within the channels of the at least one rotor blade (116) further augments torque generation;
the coordinated conversion of kinetic and potential energy into mechanical power enables a compact, high-performance turbine configuration;
static pressure is discharged into the outlet annulus upon exiting the trailing edge of the at least one rotor blade (116).