Patent Grant
11306592
The present disclosure relates to the field of reverse cycles, particularly to the improvement of the performance of refrigeration systems or compression heat pumps which utilize the phase transition, both evaporation and condensation, of a working fluid in a closed circuit.
The disclosure relates in particular to a device for energy recovery of the pressure difference between the condenser and the evaporator of the above-cited reverse cycles, which is commonly dissipated in adapted ducts having a reduced passage section or in throttling valves.
The disclosure finds a preferred and advantageous but nonlimiting application in the refrigeration industry, in order to reduce the energy consumption of compression refrigeration systems, for example those of industrial size (>100 kW electric power) or of domestic size (<10 kW electric power).
Solutions for energy recovery in refrigeration systems and heat pumps are known in the background art.
Refrigeration systems and heat pumps are also referred to as reverse cycles. Reverse cycles are divided mainly into two categories: compression systems and absorption systems.
With reference to compression systems, they are constituted typically by a closed cycle which contains a working fluid such as an R134a or R22 technical gas, which flows through, in the following order, a compressor, a condenser, a throttling valve or capillary tube, and an evaporator.
In these systems, the condenser operates at a higher pressure than the evaporator: therefore, the working fluid is transferred from the condenser, in the liquid phase, to the evaporator, in the liquid and steam phase, through a dissipation element, such as an orifice, a throttling valve or a capillary tube. Inside said dissipation element, the working fluid passes from a single-phase state (liquid) to a two-phase state (liquid and vapor), dissipating pressure energy. A fraction of lubricating oil, deriving from oil accumulation, for example, inside the compressor, also commonly circulates together with the working fluid.
The background art provides for the utilization of the pressure difference between the condenser and the evaporator by means of an expander for the production of useful power, with the dual goal of reducing the consumption of mechanical energy of the compressor and of reducing the quality (vapor mass fraction with respect to the total mass in liquid and vapor phases) of the working fluid at the inlet of the evaporator, thus increase the available enthalpy difference from evaporator inlet to evaporator outlet. The increase in performance in reverse cycles can be measured by an increase in coefficient of performance (COP). COP is typically defined as the ratio between the heat absorbed by the evaporator and the absolute value of the work that is required by the compressor. Depending on the type and size of application, COP values of reverse cycles may vary in the range 2 to 10, typically. Both the reduction in mechanical energy consumption and the reduction in quality, thanks to the introduction of a turbine between condenser and evaporator, are known to allow an increase of up to 20% of the COP of the reverse cycle.
Among devices known in the background art, in particular, U.S. Pat. No. 4,336,693-A is known which describes a refrigeration apparatus which uses a radial turbine provided with blades to provide the working fluid expansion function, providing a separation of the liquid phase from the vapor phase prior to the extraction of useful work. The useful work can be used to move a load, such as an electric generator.
Patent EP0728996-B1 describes a turbine provided with blades for a two-phase fluid in refrigeration systems that has a fluid bypass feature, in order to improve its performance for partial loads. Furthermore, said turbine can be connected to the compressor of the refrigeration cycle. This patent estimates the following increases in performance: for a 100-1000 tons refrigeration system, using a high-pressure working fluid such as R22 or R134A, and a centrifugal or screw compressor driven by a two-pole induction motor (at 3000 to 3600 rpm), the efficiency of the turbine is estimated equal to 60%. Based on the operating conditions, the turbine reduces the consumption of mechanical energy of the compressor by 6-15%, with respect to the system provided with a throttling valve.
Patent EP 0676600B1 relates to a refrigeration system which includes a turbine instead of the throttling valve, characterized by a rotor with peripheral blades.
U.S. Pat. No. 4,442,682 shows a turbine of the Banki water turbine type, therefore provided with blades, for application to refrigeration systems, in which turbine outlet the vapor fraction of the working fluid is bypassed directly at the evaporator outlet, reducing its load losses.
Patent US20130294890-A1 shows a reverse Brayton cycle provided with a bladeless compressor (boundary layer compressor) for the refrigeration of the cabin of cars. The working fluid is a single-phase gas, preferably air.
Patent CN 203131996-U describes an air conditioner for enclosed spaces in which the throttling valve is replaced with a bladed turbine, which is coupled by means of a magnetic coupling to an electric generator.
In general, it can be stated that the background art acknowledges the difficulties in designing and providing a turbine that can operate instead of the throttling valve in reverse cycles with phase transition of the working fluid.
This difficulty is due mainly to the two-phase nature of the working fluid, which in this point of the system is composed of a liquid fraction and a gas fraction.
The background art also acknowledges the difficulty of a direct coupling between said turbine and the compressor, due to the different rotational speeds.
Although the known solutions indicated above are generally functional, they have however some limitations, which so far have prevented the provision of efficient and reliable turbines in compression refrigeration cycles, in particular:
The aim of the present disclosure is to overcome the drawbacks of the background art, allowing in particular the effective recovery of the pressure energy in reverse cycles, which is typically dissipated by means of a duct having a reduced passage or by a throttling valve.
The disclosure provides a reverse cycle machine in which pressure energy recovery is provided by means of reliable components which are not, or scarcely, subject to wear and failures or malfunctions.
In particular, the present disclosure solves the problem of the erosion of a turbine operating between the high-pressure part and the low-pressure part of a compression reverse cycle, and crossed, even partially, by the working fluid that arrives from the condenser and is directed to the evaporator of said reverse cycle. This turbine would operate with the working fluid in the multiphase state, two-phase liquid and vapor in the simplest condition, also mixed with any oil that might arrive from the compressor and is circulating in the cycle. This turbine can process the working fluid for any value of the quality.
Furthermore, the present disclosure solves the problem of performance decay of turbines as the dimensions decrease, and that are significantly reduced in reverse cycles with respect to traditional applications, due to both the reduced mass flow rate of the working fluid and the high density of the processed fluid.
This aim and these and other advantages which will become better apparent hereinafter are achieved by providing a reverse cycle machine according to the corresponding accompanying independent claim, optionally having the characteristics of the dependent claims, which are understood to be an integral part of the present description.
Particularly, the disclosure provides a compression reverse cycle machine, comprising an evaporator, a compressor and a condenser arranged in series each other along a path of a working fluid in the machine,
further comprising a boundary layer turbine, placed between the condenser and the evaporator, said turbine comprising
a set of power disks mounted on a shaft which rotates inside a volume of a rotor casing,
an inlet opening for introducing a working fluid in a stator volume,
a stator nozzle, which accelerates the flow in a direction that is tangential to the power disks,
a discharge of a working fluid,
the rotor casing comprising a drain of a liquid fraction at least of said working fluid from the peripheral part of the power disks in order to avoid its concentration in the peripheral part of the volume of said rotor casing.
The underlying idea of the disclosure is to use a boundary layer turbine, also referred to as friction type or Tesla type turbine, capable of processing a single-phase or multiphase fluid in the absence of rotor blades, optionally coupled to an electric power generator.
Boundary layer machines, and in particular turbines for the generation of useful energy but also pumps or compressors, were patented in 1913 by Nikola Tesla. With particular reference to boundary layer turbines (U.S. Pat. No. 1,061,206), they use rotating flat disks without wing-like profiles or blades or impellers, so much that they are termed “bladeless”. Conceptually, the rotor in fact absorbs kinetic energy from the working fluid due to resistance forces (viscous friction) and not due to lift forces, thus utilizing the viscosity and adhesion properties of the fluids. These types of turbines are therefore suitable for working with dense fluids and with high density. Subsequently, improved variations of the boundary layer pump or turbine have been reported especially for operation with complex fluids such as multiphase fluids. In fact, in these boundary layer machines, the dense fraction of a multiphase fluid is not diverted by blades or profiles and therefore the mechanical erosion of the surface is minimal Vice versa, traditional turbines or pumps, provided with blades and profiles for the exchange of work with the fluid, are subject to rapid wear when they are used with a multiphase fluid. Likewise, for the same reasons, significant advantages have been reported in the case of operation with liquids subject to cavitation, which typically leads to a rapid decrease, due to erosion, of the performance of traditional bladed machinery.
The absence of blades or profiles that interact with the fluid furthermore leads to significant advantages in terms of vibrations, since the fluid dynamics forces that excite the vibrations on the rotating shaft in this case are minimized. Furthermore, the problem of vibrations is particularly severe in traditional turbine machines processing a multiphase fluid.
The applicability of boundary layer turbines to multiphase fluids, however, has a limitation linked to the separation of the phases caused by the centrifugal force of the rotor and due to the different density between the phases. This “centrifugation” of the multiphase fluid in fact causes the concentration of the densest phase at the periphery of the rotor.
In the case of a liquid-gas multiphase fluid (two-phase in the simplest meaning), the accumulation of liquid between the peripheral region of the rotor and the external containment casing (wheel chamber) causes the flooding of said rotor, with consequent viscous dissipation of energy. The flow of the liquid phase through the outlet at the center of the rotor, in fact, would require a higher pressure gradient than the one required by the gaseous phase.
The general idea on which the present disclosure is based provides for a compression reverse cycle machine equipped at least with a compressor, at least one evaporator and at least one condenser of the working fluid, and provided with a boundary layer turbine, operating between the high-pressure cycle part and the low-pressure cycle part of the working fluid.
More particularly, the disclosure relates to a machine with compression reverse cycle, comprising an evaporator, a compressor and a condenser arranged in series to each other along a path of a working fluid in the machine, which machine further comprising a boundary layer turbine, operating (and provided) between the condenser and the evaporator, said turbine comprising
a set of power disks mounted on a shaft which rotates inside a volume of a rotor casing
an inlet opening for introducing the working fluid in a stator volume
a stator nozzle, which accelerates the flow in a direction that is tangential to the power disks
a discharge of the working fluid
the rotor casing comprising a drain of a liquid fraction at least of the working fluid from the peripheral part of the power disks in order to avoid its concentration in the peripheral part of the power disks of the volume of said rotor casing
Said boundary layer turbine can process all or a fraction of the flow rate of the working fluid of the reverse cycle machine.
Furthermore, said boundary layer turbine can perform a partial expansion of the working fluid, assigning to another component the task of completing the expansion.
This solution offers the advantage of minimizing the erosion of the turbine, since the turbine has no blades or profiles that would be eroded by the fluid of the single- or multiphase type. In this latter case, the fluid is characterized by a quality that is variable between zero and one. Furthermore, this solution offers the additional advantage of reducing the negative impact of the scale effect on the turbine performance for small dimensions of the rotor (microturbines).
According to an advantageous embodiment, in the reverse cycle described previously, the boundary layer turbine is used to generate useful energy, for example in mechanical form. A generator for the production of electric power can be coupled to said turbine.
This solution offers the advantage of reducing the energy consumption of the reverse cycle, increasing its refrigerating capacity or heat pump thermal output, allowing for a twofold increase in its coefficient of performance (COP).
According to an advantageous embodiment, said boundary layer turbine for application to said reverse cycle is characterized by the presence of at least one drain for the discharge of the liquid fraction of the working fluid on the rotor casing (or wheel chamber). Said drain can connect the volume of the rotor casing to the outlet of the turbine or directly to the evaporator of the reverse cycle.
This solution has the advantage of avoiding the risk of flooding of the peripheral region of the rotor, due to the accumulation of the dense (liquid) fraction of the working fluid and/or of the circulating oil, if present, by centrifugal force. This allows the optimization of turbine performance, reducing viscous losses.
According to an advantageous embodiment, the above-cited discharge drain can be throttled by an apt valve with a variable cross-section in order to adjust the discharged flow rate.
This solution has the advantage of being able to adapt the size of the discharge drain to the operating condition of the reverse cycle, in order to allow the complete evacuation of the liquid fraction from the rotor casing volume without discharging also part of the vapor fraction, thus maximizing the vapor fraction of the working fluid that flows through the power disks.
According to an advantageous embodiment, the turbine has at least one rotating sealing disk, characterized by an outside diameter that is smaller than the outside diameter of said power disks and of a sealing stator element inside which it rotates; said power disks are provided with axial discharge holes, the rotating sealing disk being provided with axial discharge holes in continuity with the discharge holes of the power disks.
Preferably, the discharges of said turbine furthermore comprise radial holes for discharge and discharge passages.
Said sealing disk is furthermore characterized by apt axial-symmetrically shaped portions in order to hinder the leakage of the working fluid from the wheel chamber to the discharge holes of the turbine.
According to an advantageous embodiment, said boundary layer turbine is of the “impulse” type, in order to maximize the vapor fraction in output from the stator and at the inlet of the power disks and to minimize the leakage flow rate through the periphery of the sealing disk, such leakage flowing from the peripheral region of the rotor to the discharge holes. This solution has the advantage of maximizing the power generated by the turbine and of reducing losses due to leakage.
The disclosure provides also for a first method for adjusting said reverse cycle by means of a bypass of the working fluid around said boundary layer turbine in order to provide the complete outflow of the liquid fraction of the working fluid through said discharge drains of the wheel chamber, without however discharging the vapor fraction, also when the operating condition of the reverse cycle varies. This solution offers the advantage of minimizing the contact of the liquid fraction of the working fluid with the rotor and also of maximizing the vapor fraction of the working fluid portion passing through the rotor, with a benefit in terms of efficiency of expansion and of generated useful power.
The above cited advantage can be achieved also by means of a second method for adjusting said reverse cycle by means of a throttling valve placed upstream or downstream of the boundary layer turbine, or with both valves present, in order to provide the complete outflow of the liquid fraction of the working fluid through said discharge drains of the wheel chamber, without however discharging the vapor fraction, also when the operating condition of the reverse cycle varies.
This advantage can also be achieved by means of a third method for the adjustment of said reverse cycle, by throttling the discharge drain by a valve in order to provide the complete outflow of the liquid fraction of the working fluid through said drains, without however draining the vapor fraction, also when the operating condition of the reverse cycle varies.
In one preferred and advantageous embodiment, the three adjustment methods cited above can be present alternately in pairs or all three simultaneously.
Further advantageous characteristics are the subject matter of the accompanying claims, which are understood to be an integral part of the present description.
The disclosure is described hereinafter with reference to nonlimiting examples, provided with a nonlimiting explanatory purpose in the accompanying drawings. These drawings illustrate different aspects and embodiments of the disclosure and, where appropriate, reference numerals that illustrate structures, components, materials; elements that are similar in different figures are designated by similar reference numerals.
In the accompanying figures:
While the disclosure is susceptible of various modifications and alternative constructions, some preferred embodiments are shown in the drawings and are described hereinafter in detail.
It is to be understood in any case that there is no intention to limit the disclosure to the specific illustrated embodiment, but, on the contrary, it intends to cover all the modifications, alternative constructions, and equivalents that fall within the scope of the disclosure as defined in the appended claims.
The use of “for example”, “etc.”, “or” indicates nonexclusive alternatives without limitation unless otherwise specified.
The use of “includes” means “includes, but is not limited to” unless otherwise specified.
Indications such as “vertical” and “horizontal”, “upper” and “lower” (in the absence of other indications) are to be read with reference to the assembly (or operating) conditions and with reference to the normal terminology in use in everyday language, where “vertical” indicates a direction that is substantially parallel to the direction of the vector of the force of gravity “g” and “horizontal” indicates a direction that is perpendicular thereto.
With reference to the reverse cycle shown in
Said turbine (7) can be connected to an electrical generator (8) for the generation of electric power. Said useful work or electrical power partially compensates the consumption of work or electrical power of the compressor, thus reducing the overall energy consumption and increasing the COP. Said boundary layer turbine (7) works with a multiphase fluid, optionally two phase in the simplest case. With reference to
In the case of the present disclosure, the fluid in output from the condenser is sent to the boundary layer turbine (7). Ideally, this turbine might perform an isoentropic reversible transformation, represented between the points C-Dis. However, the actual expansion transformation will be characterized by an isoentropic adiabatic efficiency lower than 100% (that is the case of an ideal transformation), and therefore the actual transformation will be comprised between the ideal one C-Dis and the fully dissipative one of the isoenthalpic type C-D. This brings the following two advantages: the recovery of useful energy, which can be used to reduce the energy consumption of the compressor; the increase of the enthalpy difference available at the evaporator, with a consequent increase in refrigerating or heat pumping capacity. Both advantages entail an increase of COP with respect to the initial reverse cycle without the boundary layer turbine: the energy recovery in fact allows the reduction of the denominator of the COP, compensating the work spent for compression, while the enthalpy difference increase at the evaporator allows an increase of equal amount of the numerator of the COP.
Following the path of the working fluid inside the boundary layer turbine, the working fluid is fed at high pressure through apt inlet openings (70) in the stator volume. Said stator volume is represented by a volume that is defined by the external enclosure of the turbine (75) and an internal ring (50), in which an appropriate slot for the passage of the pressurized fluid has been provided. In
Stator nozzles (52) are provided in the ring (50) as through holes connecting the stator volume (51) with the rotor casing (53) itself.
The acceleration of the fluid occurs at the expense of the pressure energy, which is reduced from the stator volume to the wheel chamber. Due to said pressure reduction, the fluid increases its vapor fraction and decreases the liquid fraction: the liquid fraction can include also the lubricating oil that circulates in the reverse cycle. The vapor fraction is forced to pass through the interstitial space between the power disks, until discharge occurs through apt axial holes in the disks (35); rotor axial discharge holes (35) are provided in each power disk (30) close to the central part of the disk itself, near the rotating shaft (33).
The fluid exchanges useful work with the power disks (30) thanks to the tangential friction forces and is therefore slowed tangentially by said disks, until it exits through said rotor axial discharge holes (35).
Said rotor axial discharge holes (35) are aligned with the sealing disk axial discharge holes (32). Such sealing disks, placed on the opposite sides of the set of power disks, are pressed against the set of power disks, with no interstitial space: the fluid is therefore discharged first through the rotor axial discharge holes (35), then through the sealing disk axial discharge holes (32) provided in the sealing disk (31), and finally through the discharge ring radial holes (59) provided in the fixed discharge ring (57), to be finally collected and sent externally the enclosure (75) through the radial discharge passages (73, 74) provided in the enclosure (75) itself.
In said rotor axial discharge holes and sealing disk axial discharge holes (35, 32) the pressure is lower than the pressure at the power disk periphery and, except for small pressure losses, equal to the final discharge pressure of the turbine (at the discharge passages 73, 74). Therefore, on the two power disk surfaces facing the two opposite sealing stator elements (54), at both sides of the set of the power disks, it is important to limit the leakage losses of the working fluid from the periphery of the power disks to the rotor axial discharge holes (35) and sealing disk axial discharge holes (32).
This sealing effect is provided by the sealing disk (31), which is characterised by appropriate axial-symmetrical slots (34A) in order to hinder the leakage of the working fluid; preferably the sealing disk (31) is provided at least with an annular lip (34) that is engaged in a corresponding seat (54A) of the surrounding sealing stator element (54).
Said sealing disk (31) can be provided by a monolithic part, or by means of the assembly of multiple disks having a definite thickness: in both cases, the sealing disk (31) is characterized by outside diameters of every part of the sealing disk (31) that are smaller than the corresponding inside diameter of the respective part of the sealing stator element (54) within which it rotates, preferably smaller than 0.3%, and smaller than the diameter of the power disks (30), in order to minimize the aforementioned leakage losses.
In other words, the radial distance between the sealing disk (31) and the sealing stator element (54) is preferably smaller than 0.3% of the corresponding diameter.
Like the power disks (30), said sealing disk (31) is mounted rigidly on the rotating shaft (33).
The liquid fraction that is still present after expansion through the stator nozzles (52), instead, follows two alternative paths: to a minimal extent, it is entrained by the vapor fraction to the discharge of the turbine, and for the most part it is confined in the rotor casing, at the power disk periphery, due to the centrifugal force.
In order to evacuate said liquid fraction from the rotor casing, discharge drains (71, 72) are provided on the wall of the wheel chamber in order to collect the liquid fraction and convey it outside the enclosure of the turbine.
Particularly, said drains (71,72) are drains provided in the peripheral portion of the rotor casing (53); more in detail, the drain passage comprises a first drain portion (71A,72A) provided as a duct in the peripheral portion of said sealing stator element (54), in fluid communication with a second drain portion (71B,72B) provided in the sealing stator element (54) as a circumferential or annular channel that, in use, faces the internal wall of the housing (75) and that is on its turn in fluid communication with the hole in the housing (75).
By way of example, said drains (71,72) can convey the liquid fraction toward the general discharge of the turbine (73) or, in other embodiments, directly toward the evaporator (9) of the reverse cycle.
Discharge drain (71, 72) are preferably throttled by respective valves (not shown).
This allows to avoid the flooding of the peripheral part of the power disks, with consequent losses due to the viscous effect.
Finally, the enclosure of the turbine (75) can be closed by plugs (60) at the ends, which can accommodate apt bearings to allow the rotation of the rotating shaft (33).
It is possible to mechanically connect the compressor (1) of the reverse cycle to said rotating shaft, in order to reduce its energy consumption.
In another preferred configuration, a generator (8) for the generation of electrical power is connected to said rotating shaft.
Summarizing, the turbine (7), as shown in
In this embodiment, said drains (71,72) are drains provided in the peripheral portion of the rotor casing (53) as above described.
In another embodiment (that can be seen as a basic embodiment), the turbine (7) does not show a symmetrical structure, and the turbine (7) comprises:
In this embodiment, said drain (71) is a drain provided in the peripheral portion of the rotor casing (53) as above described.
Consider a reverse cycle, which utilizes R134a as working fluid and operates between the conditions at the evaporator (9) of 4 bar and 8.9° C. and the conditions at the condenser (3) of 16 bar and 57.9° C.; adopt the typical convention of thermodynamics, for which the positive sign is associated with the heat provided to the cycle (or absorbed by the cycle) and to the work produced by the cycle; let the coefficient of performance (COP) be the ratio between the heat absorbed by the evaporator and the absolute value of the work that is required in total by the cycle. In the case of a traditional reverse cycle, i.e. with a dissipative expansion device such as a throttling valve, assuming an isentropic adiabatic efficiency in compression equal to 80%, a COP equal to 1.98 is obtained. If the flow rate of working fluid is equal to 2 kg/s, the power absorbed by the compressor (1) is −119.3 kW. If the boundary layer turbine (7) according to the present disclosure is installed in place of the throttling valve, the power consumed in total to the reverse cycle is reduced and the COP increases, as shown in the table below, as the isoentropic adiabatic efficiency of the turbine varies.
The use of the boundary layer turbine instead of the throttling valve, together with the possibility of energy recovery has been demonstrated experimentally by means of a prototype:
The aim and objectives listed above are thus achieved.
Numerous variations to what has been described so far are obviously possible.
For example, with reference to
As a further example, with reference to
As a further example, with reference to
As a further example, with reference to
As a further example, with reference to
The disclosures in Italian Patent Application No. 102016000132467 (UA2016A009642) from which this application claims priority are incorporated herein by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102016000132467 | Jan 2017 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/084660 | 12/27/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2018/127445 | 7/12/2018 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 1061206 | Tesla | May 1913 | A |
| 4336693 | Hays et al. | Jun 1982 | A |
| 4438638 | Hays | Mar 1984 | A |
| 4442682 | Sakata | Apr 1984 | A |
| 6682077 | Letourneau | Jan 2004 | B1 |
| 20120014779 | Gilliam | Jan 2012 | A1 |
| 20130294890 | Cepeda-Rizo et al. | Nov 2013 | A1 |
| 20160258442 | Helton | Sep 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 203131996 | Aug 2013 | CN |
| 076600 | Oct 1995 | EP |
| 0728996 | Aug 1996 | EP |
| 1067342 | Jan 2001 | EP |
| 20130128903 | Nov 2013 | KR |
| 0146564 | Jun 2001 | WO |
| 2015200134 | Dec 2015 | WO |
| Entry |
|---|
| International Preliminary Report on Patentability dated Mar. 22, 2019 re: Application No. PCT/EP2017/084660; pp. 1-15; citing: U.S. Pat. No. 4,438,638 A, US 2016/0258442 A1, KR 2013 0128903 A, WO 01/46564 A1, WO 2015/200134 A1, US 2012/014779 A1 and EP 1 067 342 A2. |
| International Search Report dated Feb. 29, 2018 re: Application No. PCT/EP2017/084660; pp. 1-5; citing: U.S. Pat. No. 4,438,638 A, US 2016/0258442 A1, KR 2013 0128903 A, WO 01/46564 A1, WO 2015/200134 A1, US 2012/014779 A1 and EP 1 067 342 A2. |
| IT Search Report dated Aug. 21, 2017 re: Application No. IT 2016000132467; pp. 1-3; citing: US 2016/0258442 A1, WO 01/46564 A1, WO 2015/200134 A1, U.S. Pat. No. 6,682,077 B1 and US 2012/014779 A1. |
| Written Opinion dated Feb. 29, 2018 re: Application No. PCT/EP2017/084660; pp. 1-6; citing: U.S. Pat. No. 4,438,638 A, US 2016/0258442 A1, KR 2013 0128903 A, WO 01/46564 A1, WO 2015/200134 A1, US 2012/014779 A1 and EP 1 067 342 A2. |
| Number | Date | Country | |
|---|---|---|---|
| 20190323350 A1 | Oct 2019 | US |
