Equipment and method for converting thermal energy into mechanical and / or electrical energy

Abstract

The present invention relates to a method and an installation (1) for converting thermal energy into electrical and mechanical energy. The method and the installation (1) comprise a closed circuit (2), a pump (13) for circulating a working fluid in the closed circuit, an evaporator (3) for heating the working fluid and changing it into a gaseous state, a positive displacement expander (4) operating in the closed circuit downstream of the evaporator and acting as a gaseous input fluid, and a condenser (16) operating downstream of the positive displacement expander and upstream of the pump on the closed circuit for condensing the working fluid to ensure its transition to a liquid state. The pump comprises a first compartment in fluid communication with a first portion (2a) of the closed circuit extending downstream of the pump (13) and upstream of the evaporator for delivering the liquid working fluid to the evaporator, and a second compartment in fluid communication with a second portion (2b) of the closed circuit extending upstream of the positive displacement expander and downstream of the first portion for receiving the working fluid in a gaseous state produced by the evaporator. This encourages pumping of the liquid working fluid to the evaporator (3), causing the second compartment to expand with the gaseous working fluid and reducing the volume of the first compartment.

Description

[Technical field]

[0001] The present invention is directed to an installation and associated method in which a working fluid performs a thermodynamic cycle, in particular a closed thermodynamic cycle, such as a Rankine cycle, to generate electrical and / or mechanical power by recovering and converting heat from a high temperature source. In particular, the installation and method covered by the present invention can achieve a self-sustaining cycle since no (or only a minimal) power supply is required to pump the working fluid.

[0002] Moreover, the methods and equipment described and claimed herein are capable of efficiently extracting energy even from "high temperature" sources characterized by temperatures that are not excessively high, e.g., below 130°C, and in particular where liquid (typically water) is present at temperatures below 100°C, e.g., between 35°C and 80°C.

[0003] The present invention can be used in biogas / biomass installations to recover waste heat through a cogeneration process, geothermal installations utilizing small / medium heat sources, industrial installations to recover waste heat (conversion of waste heat from industrial processes), and domestic applications to produce electricity and utilize heat sanitarily.

[0004] Further applications for expanders and their installations include domestic and industrial systems where the heat source is provided by a solar energy capture system.

[0005] It is also conceivable to use this system in the automotive sector, for example for heat recovery from engines. [Background technology]

[0006] Installations employing positive displacement expanders, such as piston, screw or scroll type expanders, or reactive expanders such as gas turbines, are known to recover thermal energy and subsequently produce electricity.

[0007] A typical embodiment of such an installation is to use one or more turbines as expansion chambers, however this solution has limitations and drawbacks: High cost of turbines and associated inspection facilities. -Frequent maintenance is required, which is a burden. · The working fluid must be very hot and in a gaseous state at all times, otherwise the turbine will be irreparably damaged. Maximum efficiency can only be achieved if the flow rate of the expanding fluid is very precise and the rotational speed is prescribed. This is perhaps the greatest limitation of turbine systems, especially since even small deviations in rotational speed from the optimum value dramatically reduce the efficiency of the turbine.

[0008] It should also be noted that many currently available potential heat sources (think industrial wastewater, factory cooling water, etc.) are not extremely hot, often well below 100°C, and have flow rates that vary over time. Converting heat from such sources to electricity using turbines is not cost-effective in terms of the energy produced. Indeed, turbines are not suitable for use with low and medium temperature heat sources (e.g. 35 to 90°C), and their heat output often fluctuates widely. This condition makes turbines even more inconvenient to employ for thermal energy conversion.

[0009] To overcome the above-mentioned drawbacks, it is known to use reciprocating or rotary positive displacement expanders which are capable of extracting energy from heat sources that are not extremely hot and which can be operated at relatively low fluid flows without significant loss of efficiency.

[0010] WO 2010102874 and WO 2014141072 describe examples of alternative (e.g. single piston or double piston) positive displacement expander installations for converting thermal energy into mechanical and / or electrical energy that can use heat sources with temperatures below 100° C., for example around 35° C. to 130° C. Although these known alternative installations have been found to be improved over conventional turbine-based installations, particularly under the low and medium heat source conditions mentioned, the applicant has determined that further improvements can be made.

[0011] In particular, equipment that circulates a working fluid in a closed loop requires a pump system to circulate the working fluid. Since pumps currently in use are generally powered by electricity, a portion of the mechanical and / or electrical energy that can be generated in the system is actually consumed by the pump, putting a strain on the efficiency of the entire system.

[0012] Furthermore, the pumps currently in use, such as multi-stage centrifugal pumps, vane pumps, gear pumps, orbital screw pumps and spiral (scroll) pumps, are inefficient and suffer from leakage problems at the high pressure regimes typical of the thermodynamic cycles discussed here, and all suffer from significant cavitation problems. Summary of the Invention [Problem to be solved by the invention]

[0013] SUMMARY OF THE PRESENT EMBODIMENT It is therefore an object of the present invention to substantially overcome at least one of the disadvantages and / or limitations of the aforementioned solutions.

[0014] The first object of the present invention is to provide a highly efficient equipment and method, and in particular to provide an equipment and method that can achieve high efficiency by converting thermal energy into mechanical energy and / or electrical energy while operating with a high temperature source of medium to low temperature (e.g., about 35°C to 130°C).

[0015] It is also an object of the present invention to make available installations, e.g. of the Rankine cycle type, and associated methods, which can be adapted to various operating conditions so as to effectively utilize available heat sources and provide maximum power with excellent efficiency.

[0016] It is a further object of the present invention to make available an installation, e.g. of the Rankine cycle type, and an associated method, which is of simple and compact construction suitable for easy installation, resulting in extremely low production, maintenance and assembly costs.

[0017] It is also an object of the present invention to provide an installation, such as a Rankine cycle system, and associated method, in which the efficiency of the working fluid pumping system is improved.

[0018] It is a further object to provide an apparatus and method capable of realizing a self-sustaining cycle without the need for (or requiring only a minimal amount of) power to be supplied to the pumping system for the working fluid.

[0019] It is a further object of the present invention to make it possible to utilize installations and associated methods, for example of the Rankine cycle type, which do not present reliability problems in the pumping system of the working fluid and are suitable for use with the cycle pressure regimes described herein, and in which the working fluid exists in both gas and liquid states.

[0020] It is also an ancillary object of the present invention to make available an apparatus and method using a pumping system which minimizes the problems of cavitation.

[0021] Finally, it is an object of the present invention to make available an installation and a method for converting thermal energy into electrical and / or mechanical energy, which is easy to implement and can achieve good energy conversion efficiency.

[0022] These and other objects, which will become more apparent from the following description, are substantially achieved by a positive displacement expander, a closed loop plant and a method for converting thermal energy to electrical energy according to one or more of the appended claims and / or according to the following aspects, either alone or in combination with each other, in combination with any one of the claims and / or in combination with any one of the further aspects or features described below. [Means for solving the problem]

[0023] Aspects of the present invention are described below.

[0024] In a first aspect, there is provided an apparatus (1) comprising: A closed circuit (2) in which at least one working fluid circulates. At least one pump (13) operating in the closed circuit (2) and arranged to circulate a working fluid in the circuit. At least one expander (4) configured to receive as an input a working fluid in a gaseous state. Here, the pump (13) includes: At least one first compartment (20) that can be arranged in fluid communication with a first portion (2a) of the closed circuit (2) extending downstream of the pump and that propels the working fluid in a liquid state in the closed circuit towards the first portion. At least one second compartment (21), which may be arranged in fluid communication with a second part (2b) of the closed circuit, extending downstream of the first part (2a) and upstream of the expander (4), and which receives the working fluid in a gaseous state, present in the second part of the closed circuit.

[0025] In a second aspect, although not necessarily in accordance with the first aspect, there is provided an installation (1) comprising: A closed circuit (2) in which at least one working fluid circulates. At least one pump (13) operating in the closed circuit (2) and arranged to circulate a working fluid in the circuit. At least one evaporator (3) operatively connected to the closed circuit (2) and configured to receive heat from a high temperature source (H) and heat the working fluid to cause it to transition from a liquid to a gaseous state. At least one expander (4), operatively disposed downstream of the evaporator (3) in the closed circuit (2) and configured to receive as input a working fluid in a gaseous state. At least one condenser (16) operating in the closed circuit (2), downstream of the expander (4) and upstream of the pump (13), configured to condense the working fluid by establishing a transition of the working fluid from a gaseous state to a liquid state. Here, the pump (13) includes: A first compartment (20) arranged in fluid communication with at least a first portion (2a) of the closed circuit (2) extending downstream of the pump (13) and upstream of the evaporator (3) and configured to deliver the working fluid in a liquid state to the evaporator (3). A second compartment (21) arranged in fluid communication with at least a second portion (2b) of the closed circuit extending downstream of the first portion (2a) and upstream of the expander (4) and configured to receive the working fluid in a gaseous state produced by the evaporator (3).

[0026] In a third aspect according to any one of the previous aspects, the expander (4) is one or more piston (reciprocating or rotary), screw, scroll, or other type of positive displacement expander.

[0027] In a fourth aspect according to any one of the first or second aspects, the expander (4) is a reactive expander comprising one or more gas turbines.

[0028] In a fifth aspect according to any one of the preceding aspects, the facility is configured to convert thermal energy into electrical and / or mechanical energy.

[0029] In a sixth aspect according to any one of the aspects described above, the pump is configured to determine an increase in volume in the second compartment (21) following the flow of the working fluid in a gaseous state from the second portion (2b) into the second compartment (21), thereby promoting a decrease in volume in the first compartment (20) and transporting the working fluid in a liquid state towards the evaporator (3).

[0030] In a seventh aspect according to any one of the above-mentioned aspects, the first compartment (20) can be selectively configured in a corresponding first operating state in which it is in fluid communication with the first portion (2a) of the closed circuit (2) and in a corresponding second operating state in which it is in fluid communication with a third portion (2c) of the closed circuit (2) extending downstream of the condenser (16) and upstream of the pump (13) to receive the working fluid in a liquid state from the condenser (16).

[0031] In an eighth embodiment according to any one of the preceding embodiments, the second compartment (21) can be selectively configured in a corresponding first operating state in which it is in fluid communication with the second portion (2b) of the closed circuit (2) and in a corresponding second operating state in which it is in fluid communication with the third portion (2c) of the closed circuit (2) upstream of the pump (13) for discharging the working fluid in a gaseous state to the third portion (2c).

[0032] In a ninth aspect according to any one of the two aforementioned aspects, the equipment is configured to maintain the first compartment (20) in a corresponding first operating state when the second compartment (21) is in a corresponding first operating state, and to maintain the first compartment (20) in a corresponding second operating state when the second compartment (21) is in a corresponding second operating state.

[0033] In a tenth aspect according to any one of the previous aspects, the installation comprises at least one recovery tank (17) operating in the third part (2c) of the closed circuit (2) and interposed between the condenser (16) and the pump (13), the recovery tank (17) configured to receive the working fluid from the condenser (16) and to contain a working fluid in a liquid state in equilibrium with the working fluid in a gaseous state.

[0034] In an eleventh embodiment according to the above-mentioned embodiments, the first compartment (20) is in fluid communication with an area of ​​the recovery tank (17), in particular the lower area (17a) of the recovery tank where the working fluid in liquid state is present, in order to receive the working fluid in liquid state from the recovery tank in a corresponding second operating state.

[0035] In a twelfth aspect according to any one of the two previous aspects, the second compartment (21) is in fluid communication with an area of ​​the recovery tank (17), in particular with the upper area (17b) of the recovery tank where the working fluid in a gaseous state is present, in order to discharge the working fluid in a gaseous state to the recovery tank in a corresponding second operating state.

[0036] In a thirteenth aspect according to any one of the previous aspects, the pump (13) includes a housing and at least one piston operating within the housing.

[0037] In a fourteenth aspect according to the previous aspects, the piston has a first apex that cooperates with the housing to define a first compartment (20) and a second apex that cooperates with the housing to define a second compartment (21).

[0038] In a fifteenth aspect according to the aforementioned aspects, the first apex and the second apex are connected to each other.

[0039] In a sixteenth aspect according to the preceding aspects, the first apex and the second apex are rigidly connected.

[0040] In a seventeenth aspect according to the fifteenth or sixteenth aspects, the first apex and the second apex are connected to each other as follows. It is determined that when each of the first compartment (20) and the second compartment (21) is in a corresponding first operating state, the gaseous working fluid produced by the evaporator (3) flowing into the second compartment (21) causes the second top of the piston to move and displaces the first top, discharging the liquid working fluid from the first compartment (20) and sending it towards the evaporator (3).

[0041] In an eighteenth aspect according to the fifteenth or sixteenth or seventeenth aspects, the first apex and the second apex are connected to each other as follows. It is determined that when each of the first compartment (20) and the second compartment (21) is in a corresponding second operating state, the liquid working fluid flowing into the first compartment (20) causes the first top of the piston to move, displacing the second top and discharging the gaseous working fluid from the second compartment (21) and sending it towards the third part (2c) of the closed circuit (2) extending downstream of the condenser (16) and upstream of the pump (13).

[0042] In a nineteenth aspect according to any one of the four previous aspects, the pump includes a drive member acting on the piston to reciprocate the piston along a predetermined stroke within the housing, optionally including an electric motor, a hydraulic motor, an electric actuator, a hydraulic actuator, or a pneumatic actuator.

[0043] In a twentieth aspect according to any one of the fifteenth to eighteenth aspects, the housing defines at least first and second working chambers each defining a corresponding volume hydraulically separated from one another and fillable with a working fluid, where the volume of the second chamber is greater than the volume of the first chamber.

[0044] In a twenty-first embodiment according to the previous embodiments, the volume of the second chamber is at least 1.5 times larger than the volume of the first chamber, such as 1.5 times, 1.75 times, 2 times, 2.25 times, 2.5 times, 2.75 times, 3 times.

[0045] In a twenty-second aspect according to the twentieth or twenty-first aspect, the first chamber and the second chamber extend equally in the axial direction, in other words equally in the piston movement direction, but have different cross sections.

[0046] In a twenty-third aspect according to the twentieth, twenty-first or twenty-second aspects, a first piston top is slidably received in the first chamber and a second piston top is slidably received in the second chamber.

[0047] In a twenty-fourth aspect according to the previous aspects, the first apex and the second apex are rigidly connected, and an effective cross-sectional area of ​​the first apex is smaller than an effective cross-sectional area of ​​the second apex.

[0048] In a 25th aspect according to the above-mentioned aspects, the first apex and the second apex are firmly connected by a rod extending laterally therebetween and fluid-tightly penetrating the partition between the first chamber and the second chamber.

[0049] In a twenty-sixth aspect according to any one of the twentieth to twenty-fifth aspects, a first piston top separates the first chamber into a first section (20) and a third section (22) of the pump, the first section (20) and the third section (22) extending on either side of the first piston top and causing a change in volume as the position of the first top changes within the first chamber.

[0050] In a twenty-seventh aspect according to any one of the twentieth to twenty-sixth aspects, the second piston top separates the second chamber into a second section (21) and a fourth section (23) of the pump. The second and fourth sections (23) extend on either side of the second piston top and cause a change in volume as the position of the second top changes within the second chamber.

[0051] In a twenty-eighth aspect according to any one of the twenty-sixth or twenty-seventh aspects, the first section (20) is adjacent to the third section (22), the third section (22) is adjacent to the fourth section (23), and the fourth section (23) is adjacent to the second section (21), in that order.

[0052] In a 29th aspect according to any one of the 26th or 27th or 28th aspects, the third compartment (22) is in fluid communication with the third part (2c) of the closed circuit (2) upstream of the pump (13), in particular with an upper area of ​​the recovery tank (17), where the working fluid in gas phase is present.

[0053] In a 30th aspect according to any one of the 26th or 27th or 28th or 29th aspects, the fourth compartment (23) can be selectively configured in a corresponding first operating state in which it is in fluid communication with the second part (2b) of the closed circuit (2) and in a corresponding second operating state in which it is in fluid communication with the third part (2c) of the closed circuit (2) upstream of the pump (13), in particular with an upper area of ​​the recovery tank (17) where the working fluid in a gaseous state is present, in order to discharge the working fluid in a gaseous state into the third part (2c).

[0054] In a thirty-first aspect according to any one of the twenty-sixth or twenty-seventh or twenty-eighth or twenty-ninth or thirtieth aspects, the equipment (1) is configured to maintain the fourth compartment (23) in a corresponding second operating state when the second compartment (21) is in a corresponding first operating state, and to maintain the fourth compartment (23) in the corresponding first operating state when the second compartment (21) is in the corresponding second operating state.

[0055] A thirty-second embodiment according to any one of the embodiments described above includes at least one valve assembly (50) in communication with the pump (13).

[0056] In a thirty-third aspect according to the above-mentioned aspects, the valve assembly (50) is configured as follows. Selectively setting a first section (20) of the pump (13) to a corresponding first or second operating state. Selectively setting the second section (21) of the pump (13) to a corresponding first or second operating state.

[0057] In a thirty-fourth aspect according to the above-mentioned aspects, the valve assembly (50) is configured to place the first section (20) of the pump (13) in a corresponding first operating state when the second section (21) is in a corresponding first operating state, and to place the first section (20) in a corresponding second operating state when the second section (21) is in a corresponding second operating state.

[0058] In a thirty-fifth aspect according to the thirty-second or thirty-third or thirty-fourth aspect, the valve assembly (50) includes a first check valve (51) that operates as needed in the first part (2a) of the closed circuit (2) so that the liquid state working fluid flowing out of the first compartment (20) can be supplied to the evaporator (3).

[0059] In a thirty-sixth embodiment according to the above-mentioned embodiments, the valve assembly (50) includes a second check valve (52) that operates as needed in the third part (2c) of the closed circuit (2) to allow liquid-state working fluid coming from the third part (2c) to flow into the first compartment (20).

[0060] In a thirty-seventh aspect according to the thirty-fifth or thirty-sixth aspects, the valve assembly (50) includes a third check valve (56) operating on a supply pipe (32) connecting the second compartment (21) and the second part (2b) of the closed circuit (2) as needed to allow the gaseous working fluid produced by the evaporator (3) to flow into the second compartment (21).

[0061] In a thirty-eighth aspect according to the thirty-fifth or thirty-sixth or thirty-seventh aspect, the valve assembly (50) includes a fourth check valve (57) operating, if necessary, on a further supply pipe (33) connecting the second compartment (21) and the third part (2c) of the closed circuit (2) so as to be able to discharge the working fluid in gaseous state from the second compartment (21) to the third part (2c) of the closed circuit.

[0062] In a thirty-ninth aspect according to any one of the thirty-second to thirty-fourth aspects, the valve assembly (50) is further configured to selectively place the fourth section (23) in a corresponding first operating state or a second operating state, and to place the fourth section (23) in the corresponding second operating state when the second section (21) is in the corresponding first operating state, and conversely, to place the fourth section (23) in the corresponding first operating state when the second section (21) is in the corresponding second operating state.

[0063] In aspect 39-2 according to any one of aspects 32 to 34 or 39, the valve assembly (50) includes a first check valve (51) that operates as needed in the first part (2a) of the closed circuit (2) to enable the liquid state working fluid flowing out of the first compartment (20) to be supplied to the evaporator (3).

[0064] In a fortieth aspect according to any one of the thirty-second to thirty-fourth, or thirty-ninth, or thirty-nine-two aspects, the valve assembly (50) includes a second check valve (52) that operates, as required, in the third part (2c) of the closed circuit (2) to allow the working fluid in a liquid state coming from the third part (2c) to flow into the first compartment (20).

[0065] In a forty-first aspect according to any one of the thirty-second to thirty-fourth, or thirty-ninth, or thirty-nine-two, or fortieth aspects, the valve assembly (50) includes a selector switch (53) having at least four directions and two positions, in a first position, setting the second section (21) to a corresponding first operating state while simultaneously setting the fourth section (23) to a corresponding second operating state, and in a second position, setting the second section (21) to a corresponding second operating state while simultaneously setting the fourth section (23) to a corresponding first operating state.

[0066] In a forty-second aspect according to any one of the preceding aspects, the arrangement includes a level sensor (3c) associated with the evaporator (3).

[0067] In a forty-third aspect according to any one of the preceding aspects, the arrangement includes a level sensor (17c) associated with the tank (17).

[0068] A forty-fourth aspect according to any one of the two previous aspects includes a control unit (100) communicatively connected to a level sensor (3c) associated with the evaporator. The level sensor transmits at least a corresponding signal related to a liquid level in the evaporator (or a liquid level in a liquid collection compartment associated with the evaporator) to the control unit (100). The control unit (100) is configured to receive the signal and, in response to the signal, control or not control the operation of the pump (13), for example by manipulating the positioning of the selector (53) or by operating the drive member (70) based at least on the signal.

[0069] A forty-fifth aspect according to any one of the three aspects described above includes a control unit (100) communicatively connected to a level sensor (17c) associated with the tank. The level sensor transmits at least a corresponding signal related to the liquid level in the tank to the control unit (100). The control unit (100) is configured to receive the signal and, in response to the signal, control or not control operation of the pump (13), for example by manipulating the positioning of the selector (53) or by actuating the drive member (70) based at least on the signal.

[0070] In a forty-sixth aspect according to any one of the aforementioned aspects, the arrangement includes at least one stroke end sensor (60) associated with the pump to detect when the piston (15) reaches a corresponding stroke end position.

[0071] In a forty-seventh aspect according to the previous aspects, the end-of-stroke sensor is configured to directly control reversal of piston motion, for example by sending a command signal to a selector or a drive member.

[0072] In a forty-eighth aspect according to the forty-sixth or forty-seventh aspect, the end-of-stroke sensor is configured to issue a corresponding command signal to the control unit (100). The control unit (100) is configured to command a reversal of the motion of the piston (15), for example by manipulating the positioning of the selector (53) or by commanding actuation of the drive member (70).

[0073] In a forty-ninth aspect according to any one of the above-mentioned aspects, the control unit (100) is configured to control reversal of motion of the piston (15) at predetermined regular time intervals, for example by manipulating the positioning of the selector (53) or by controlling the operation of the drive member (70).

[0074] In a 50th aspect according to any one of the preceding aspects, the evaporator (3) includes at least a first heat exchanger having a side configured to receive heat from a high temperature source (H) and a side that intersects with the second portion (2b) of the closed circuit.

[0075] In a fifty-first aspect according to any one of the preceding aspects, the condenser (16) includes at least a second heat exchanger interposed between the expander (4) and the pump (13) and having a side intersecting with the third portion (2c) of the closed circuit (2), as well as a side configured to interact with the low temperature source (C) and cause condensation of the working fluid intersecting that portion, thereby determining a transition from a gaseous state to a liquid state.

[0076] In a 52nd embodiment according to the two previous embodiments, the equipment includes at least a third heat exchanger (18) interposed between the expander (4) and the condenser (16) and having a cross-sectional side of the closed circuit and a cross-sectional side of the first part (2a) of the closed circuit, for determining preheating of the liquid state working fluid leaving the pump (13) and heading to the evaporator (3).

[0077] In a fifty-third aspect according to any one of the preceding aspects, the facility is configured to implement a closed Rankine cycle.

[0078] In a fifty-fourth aspect according to any one of the preceding aspects, the apparatus is configured to drive the pump without the use of electricity.

[0079] In a fifty-fifth aspect according to any one of the preceding aspects, the installation is energy independent in the sense that, apart from the high temperature and low temperature sources, no energy supply from any other energy source is used.

[0080] In a fifty-sixth aspect according to any one of the preceding aspects, the installation includes at least one power generating device (12) connected to a main shaft (11) of the positive displacement expander (4), the generating device (12) configured to generate electrical energy as a result of rotation of the main shaft (11).

[0081] In a fifty-seventh aspect according to any one of the preceding aspects, the positive displacement expander (4) includes: At least one piston (5) defining an expansion chamber (6) of variable volume. A main shaft (11) kinematically connected to the piston (5) and configured to rotate about a main axis. At least one valve (8) configured to selectively open and close the inlets and outlets (9, 10) to the expansion chamber (6).

[0082] In a fifty-eighth aspect according to the above-mentioned aspects, the valve (8) is configured and controlled to achieve at least the following states: The state in which the working fluid is introduced into the expansion chamber (6). The expansion of the working fluid in the expansion chamber (6). The working fluid is discharged from the expansion chamber (6).

[0083] A fifty-ninth aspect relates to a method for converting thermal energy into electrical energy using an apparatus according to any one of the previous aspects.

[0084] A sixtieth aspect relates to a method for converting thermal energy into mechanical energy using an installation according to any one of the first to fifty-eighth aspects.

[0085] In a sixty-first aspect, particularly according to the fifty-ninth or sixty-first aspect, there is provided a method comprising: - Installing equipment (1) according to any one of aspects 1 to 58. Use of a pump (13) to pump the working fluid in liquid state into the closed circuit (2), utilizing the working fluid in gaseous state supplied from the closed circuit itself.

[0086] In a sixty-second embodiment according to the sixty-first embodiment, the working fluid in gaseous state used by the pump to pump the working fluid in liquid state comes from a part of the circuit (2) upstream of an expander used for mechanical and / or electrical power generation.

[0087] In a sixty-third aspect according to any one of the four preceding aspects, the method includes: The working fluid is evaporated in an evaporator (3). The working fluid flowing out of the evaporator (3) is expanded in a positive displacement expander (4) to generate mechanical or electrical energy by a generator (12) mechanically connected to the positive displacement expander. The working fluid flowing out of the positive displacement expander (4) is condensed in a condenser (16). Using a pump (13), pumping the working fluid in liquid state coming from the condenser (16) to the evaporator (3).

[0088] In a 64th embodiment according to the above-mentioned embodiments, the pump pumps the liquid working fluid coming from the condenser (16) towards the evaporator (3) using a working fluid in a gaseous state produced by the evaporator (3) and drawn from the evaporator (3) itself or from a second part (2b) of the closed circuit (2) contained between the evaporator (3) and the positive displacement expander (4).

[0089] In a 65th aspect according to any one of the 58th to 64th aspects, the method includes: In the second section (21) of the pump, receiving pressurized gaseous working fluid from the second part (2b) of the closed circuit (2) and displacing the piston (15) so that the second top pushes the working fluid in gaseous state present in the fourth section (23) at the discharge to the third part (2c) of the circuit, in particular the tank (17), while the first top pushes the working fluid in liquid state present in the first section (20) to the first part (2a), in particular the evaporator (3). When the stroke end is reached, the movement of the piston (15) is reversed, for example by a control device moving a selector switch (53), increasing the volume of the first compartment (20) and moving the first top so as to draw the working fluid in liquid state back into the first compartment, the fourth compartment (23) connected to the second part (2b) of the circuit receives the fluid in gaseous state and under high pressure produced by the evaporator, and the second compartment (21) discharges the working fluid in gaseous state into the third part (2c) of the circuit, in particular into the tank (17).

[0090] In a 66th aspect according to any one of the 58th to 64th aspects, the method includes: Receiving, in a second compartment (21) of the pump, a working fluid in gaseous state and under pressure coming from the second part (2b) of the closed circuit 2. Operate the drive member (70) to move the piston (15) so that the first top pushes the liquid state working fluid present in the first compartment (20) towards the evaporator (3) while simultaneously filling the second compartment (21) with the high pressure working fluid in gaseous form produced by the evaporator (3). Upon reaching the end of the stroke, reversing the movement of the piston (15), for example by controlling the reversal of the movement of the drive member (70), to move the first top and increase the volume of the first compartment (20), drawing working fluid in a liquid state from the third part (2c) of the circuit (2) into the first compartment and simultaneously expelling fluid in a gaseous state from the second compartment (21) of the circuit into the third part (2c). [Brief description of the drawings]

[0091] Embodiments and aspects of the present invention will become apparent from the following description, with reference to the accompanying drawings, given by way of non-limiting example, in which: [Figure 1] FIG. 2 is a schematic diagram of a closed-loop installation of a first embodiment of the invention in a first operating state. [Diagram 2] 2 is a schematic diagram of the installation of FIG. 1 in a second operating state; [Diagram 3] FIG. 2 is a schematic diagram of a closed-loop installation of a second embodiment of the invention in a first operating state. [Figure 4] 4 is a schematic diagram of the installation of FIG. 3 in a second operating state; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0092] Definitions and Rules It should be noted that in this detailed description of the present invention, corresponding parts shown in the various figures are designated with the same reference numerals.

[0093] The drawings may illustrate the subject matter of the invention by means of a representation that is not to scale, and therefore the illustrated parts and components relating to the subject matter of the invention may only be of schematic representation.

[0094] The term working fluid is understood to mean, for example, organic type fluids (ORC fluids). In particular, working fluids that can be used with the described installation include organic fluids, constituted in an amount of 90% to 99%, in particular 95% to 99%, and even more particularly about 98%. The organic type fluids are preferably mixed with at least one oil, configured to allow lubrication of the moving elements inside the positive displacement expander. For example, the organic fluids used can include at least one fluid (single ASHRAE refrigerant) selected from the group consisting of R134A, R245FA, R1234FY, R1234FZ, R245 sas 3G, R744, R32, R420, R520.

[0095] The possibility of using other working fluids suitable for use in the installations and methods described herein is not excluded.

[0096] In the following description and in the claims, the terms upstream and downstream refer to the direction in which the working fluid circulates within the closed circuit 2 of the installation 1.

[0097] Parts common to Figures 1, 2 and 3, 4 Parts common to the exemplary installations of Figs. 1, 2, 3 and 4 The first part of the following description will show aspects common to the installations of FIGS. 1 and 2 and those of FIGS.

[0098] With reference to the attached figures 1 to 4, reference number 1 denotes a closed cycle installation, for example a Rankine cycle, for converting thermal energy into electrical and / or mechanical energy. The installation 1 can be applied, for example, in biogas / biomass installations recovering waste heat by a cogeneration process, in geothermal installations using small / medium heat sources, in industrial installations recovering waste heat (conversion of waste heat from industrial processes), in domestic applications for producing electricity and hygienic heat use. Further applications of the installation 1 relate to both domestic and industrial systems, where the heat source is provided by a system using solar energy. The use of the installation in the automotive sector can also be envisaged, for example to recover heat from the engine or exhaust gases or heat dissipated by the radiator.

[0099] The installation 1 comprises a closed circuit 2 in which a working fluid circulates. In particular, this working fluid is a fluid of the type defined above.

[0100] As can be seen from the schematic diagrams of FIGS. 1 to 4, the installation 1 comprises at least one pump 13 arranged in the circuit 2 and suitable for moving a working fluid according to a defined direction of circulation.

[0101] The working fluid entering the pump 13 is in liquid state at a predefined pressure, in particular a pressure that corresponds substantially to the minimum pressure of the circuit. The pump 13 is configured to apply a predefined pressure jump to the working fluid, bringing it substantially to the maximum pressure of the circuit 2. The pressure jump used by the pump 13 depends on the size of the pump 13 and is preferably greater than 5 bar, in particular comprised between 5 bar and 25 bar, and even more particularly between 5 bar and 20 bar. The pressure jump used by the pump 13 causes the working fluid to circulate in the circuit 2 and, in particular, when it leaves the pump 13, to reach the first heat exchanger or evaporator 3, which is in an operational state on the circuit 2. In practice, the working fluid in liquid state pushed by the pump 13 is fed to the evaporator 3, which is configured to heat the fluid until a point in time that determines the transition from the liquid to the gaseous state.

[0102] More specifically, the evaporator 3 is suitable for receiving a working fluid in a flow path and further for receiving heat from a high temperature source H suitable for changing the state of the working fluid, thereby allowing the fluid to be heated. At the outlet of the evaporator 3, the working fluid is in a vapor state, in particular in a saturated vapor state. Structurally, the evaporator 3 can comprise, for example, one or more recovery tanks (suitable for receiving a liquid phase) as well as one or more heat exchangers suitable for utilizing as a high temperature source H a further working fluid (for example an industrial waste liquid), for example coming from a different industrial installation, in order to convert the working fluid from liquid to gas. Alternatively, the evaporator 3 can comprise a boiler suitable for changing the state of the working fluid by a high temperature source H obtained by combustion. The heating fluid from the high temperature source can be at a temperature below 150°C, in particular between 25°C and 130°C. In the illustrated embodiment, the evaporator 3 comprises a first exchanger, in which the working fluid flows through a first side 3a of the first exchanger and is gradually converted to gas by a hot fluid from a hot source H connected to a second side 3b of the first exchanger 3. As can be seen, in the illustrated non-limiting embodiment, these fluids move relative to one another.

[0103] The evaporator 3, and in particular its liquid recovery area, can have associated therewith a level sensor 3c capable of signalling the liquid level in the evaporator (e.g. in its associated tank). For example, the level sensor 3c can comprise one or more sensor elements suitable for activating when a corresponding level is reached, or a transducer suitable for emitting an electrical or electromagnetic signal proportional to the liquid level, or a simple mechanical float device suitable for sensing the liquid level and activating an electrical or mechanical control. The signal(s) from the level sensor 3c can be transmitted to a control unit 100 (e.g. comprising one or more digital CPUs associated with a corresponding memory, or one or more analogue units, or a combination of one or more digital units associated with a corresponding memory and one or more analogue circuits) programmed with at least one corresponding program or configured to selectively command the activation or deactivation of the pump 13 for the fluid circulation depending on the liquid level in the evaporator. Alternatively, the control unit 100 may be configured to command a valve assembly 50 associated with the pump 13, or to command a drive member 70 of the pump 13, to hydraulically connect or disconnect itself from the circuit 2, depending on the level sensed by the sensor 3a. In case the level sensor 3a is a mechanical device such as a float, the device may be kinematically connected to a switch of the pump for controlling the activation or deactivation of the pump 53, or to a switch of the drive member 70 as mentioned above, or to at least one valve assembly associated with the pump, and may hydraulically isolate or not isolate itself from the circuit 2 depending on the level sensed by the sensor 17c.

[0104] It is noteworthy how, along the direction of circulation of the working fluid in the circuit 2, the working fluid in gaseous state leaving the evaporator 3 enters a positive displacement expander 4 arranged to convert the thermal energy of the working fluid into mechanical energy.

[0105] The positive displacement expander 4 is of known type and comprises at least one piston 5, suitable for example to define at least one expansion chamber 6, the volume of which is variable. The positive displacement expander 4 may further comprise a transmission member, for example a crank gear 7, connected on one side to the piston and on the other side to a main shaft 11 arranged to rotate about a corresponding axis. The positive displacement expander 4 preferably comprises at least one valve 8 arranged to selectively allow the entry of the working fluid into the chamber 6 through at least one inlet 9, the expansion of the fluid in the chamber 6 and the discharge of the working fluid from the expansion chamber 6 through at least one outlet 10, thus generating a movement of the piston 5, so that the main shaft 11 can rotate about its axis. It is noted that a transmission (not shown) may be provided, connected on the one hand to the valve 8 and on the other hand to the main shaft 11, in order to synchronize the inlet, expansion and discharge states of the working fluid with the rotation of the main shaft 11 (alternatively, this synchronization may be managed by an electric or electronic system).

[0106] For example, as can be seen from Figures 1 and 2, the installation 1 further comprises at least one power generator 12 connected to the main shaft 11 and suitable for converting the rotation of the main shaft into electrical energy. In particular, the generator 12 may comprise at least one rotor connected to the main shaft 11 and capable of moving by rotation relative to a stator. Due to the relative motion between the rotor and the stator, electrical energy may be generated.

[0107] The positive displacement expander 4 may obviously include more than one piston and may, for example, be of the type described in International Application No. 2010102874 and International Application No. 2014141072.

[0108] It can be seen that the installation 1 includes at least a second heat exchanger or condenser 16, which is in a state of operation in the circuit 2 itself, along the direction of movement of the working fluid in the circuit 2. As can be seen for example in FIG. 1, the condenser 16 is interposed between the expander 4 and the pump 13. The second heat exchanger or condenser 16 is arranged to receive the working fluid leaving the expander 4 and to change it from a gaseous state to a liquid state. More specifically, the condenser 16 is arranged to receive the working fluid on a first side 16a and to communicate with a cold source C suitable for removing heat from the fluid flowing through the condenser 16. This cold source can be for example the environment and can preferably comprise one or more fans suitable for blowing cold air (i.e. at room temperature) towards the second side 16b of the heat exchanger or condenser 16, in countercurrent to the flow of the working fluid flowing through the first side 16a. The working fluid leaving the condenser 16 returns in a liquid state to the inlet of the pump 13.

[0109] The following description and claims set forth the following: A first part 2a of the closed circuit 2, which is part of the closed circuit extending downstream of the pump 13 and upstream of the evaporator 3, and which is suitable for conveying the working fluid in liquid state from the pump 13 to the evaporator 3 itself. a second part 2b of the closed circuit 2, which is part of a closed circuit extending upstream of the positive displacement expander 4 and downstream of the first part 2a, and which is suitable for receiving the working fluid in gaseous state produced by the evaporator 3 and for sending it to the expander 4. a third part 2c of the closed circuit 2, which is part of the closed circuit extending downstream of the condenser 16 and upstream of the pump 13 and which is suitable for conveying the working fluid in liquid state coming from the condenser 16 towards the pump and for recovering the working fluid in a tank 17 described below (as will be seen below). A fourth portion 2d of the closed circuit 2, which is part of the closed circuit extending downstream of the expander 4 and upstream of the condenser 16 and is suitable for sending the expanded, still gaseous, working fluid to the condenser 16.

[0110] According to a further embodiment, the working fluid in liquid state is led to a recovery tank 17, arranged on the circuit 2 between the condenser 16 and the pump 13. The function of the recovery tank 17 is to recover and contain the working fluid in liquid state leaving the condenser 16 in a lower area 17a of the tank itself, so that the pump 13 draws in the liquid without air bubbles, as shown in the attached figure. In particular, the tank 17 prevents the pumping of working fluid containing air bubbles, which could lead to the failure of the entire installation 1. In practice, the gas phase is contained in the tank 17, which is not connected to the outside environment in an upper area 17b of the tank itself, but is connected to part of the closed circuit. A level sensor 17c can be associated with the tank 17, in particular to the liquid recovery area 17a at the bottom of the tank, suitable for indicating the liquid level in the tank. For example, the level sensor 17c can be composed of one or more sensor elements that can be activated when a corresponding level is reached, or a transducer that can emit an electrical or electromagnetic signal proportional to the liquid level, or a simple mechanical float device that can sense the liquid level and activate an electrical or mechanical command. The signal from the level sensor 17c can be sent to a control unit 100 that is programmed or configured to selectively command the activation or deactivation of the fluid circulation pump 13 or the drive member 70 depending on the liquid level in the tank 17. Alternatively, the control unit 100 can be configured to control the valve assembly 50 associated with the pump 13 to hydraulically connect or isolate the pump itself from the circuit 2 depending on the level detected by the sensor 17c. If the level sensor 17c is a mechanical device such as a float, this device can be kinematically connected to a pump switch for controlling the activation or deactivation of the pump 13 or the aforementioned drive member 70 depending on the level detected by the sensor 17c, or to at least one valve associated with the pump for controlling whether the pump itself is isolated from the circuit 2 or not.

[0111] According to a further aspect, in order to determine the pre-heating of the working fluid in the liquid state leaving the pump 13 and led to the evaporator 3 by the hot gas from the expander 4, the installation 1 includes at least a third heat exchanger 18 interposed between the expander 4 and the condenser 16 and having a first side 18a intersecting with a cross section of the fourth portion 2d of the closed circuit, and a second side 18b intersecting with a cross section of the first portion 2a of the closed circuit.

[0112] The embodiment of FIG. 1 and FIG. 2 Referring now to a more detailed description of pump 13 in Figures 1 and 2, it should first be noted that although this specification describes an installation having a single pump 13, there may be multiple pumps 13, for example operating in parallel or series, or in other configurations with appropriate interposition and synchronization.

[0113] The pump 13 shown in Figures 1 and 2 includes a housing 14 defining therein at least a first working chamber 14a and a second working chamber 14b, each defining a corresponding volume that is hydraulically isolated from one another and that can be filled with a working fluid. As shown in Figures 1 and 2, the volume of the second chamber 14b is greater than the volume of the first chamber 14a. For example, the volume of the second chamber can be at least 1.5 times, or at least 2.0 times, the volume of the first chamber.

[0114] Inside the housing 14, a piston 15 operates, which has a first top 15a and a second top 15b. The first top 15a of the piston is slidably received in the first chamber 14a, and the second top 15b of the piston is slidably received in the second chamber 14b. The first and second tops are further rigidly connected to each other. In a specific case, the first and second tops are connected by a rod 15d that extends transversely to the first and second tops 15a, 15b and penetrates the separation wall 40 between the first and second chambers in a liquid-tight manner. As can be seen in Figures 1 and 2, the piston 15 moves back and forth in the housing 14 along a given axis X, and the first and second tops 15a, 15b also move back and forth in the corresponding first and second chambers 14a, 14b. The first and second chambers are prismatic, in particular cylindrical, and the first and second apexes also have a polygonal or preferably circular cross section (perpendicular to the axis X). The first and second apexes have a contour that fits against the inner surface of the corresponding chamber, since they must slide fluid-tight in the corresponding chamber. The stroke length of the first apex in the first chamber is preferably equal to the stroke length of the second apex in the second chamber. Similarly, in the illustrated embodiment, the extension of the first chamber along the axis X is equal to the extension of the second chamber along the same axis X, but the second chamber has a significantly larger radial footprint than the first chamber, for example the area of ​​the second chamber's cross section perpendicular to the axis X may be at least 1.5 times, or at least 2.0 times, the area of ​​the corresponding cross section perpendicular to the axis X of the first chamber. As a result, the first apex has an effective cross-sectional area (i.e., the area of ​​the surface that effectively propels a fluid, measured perpendicular to axis X) that is smaller than the effective cross-sectional area of ​​the second apex; for example, the area of ​​the effective cross-sectional area of ​​the second apex can be at least 1.5 times, or at least 2.0 times, the area of ​​the effective cross-sectional area of ​​the second apex.

[0115] The first top 15a of the piston, in conjunction with the housing 14, defines a first compartment 20 and a third compartment 22, which is on the opposite side of the first compartment with respect to the first top 15a (the first and third compartments 20, 22 are part of the first chamber 14a). Furthermore, the second top 15b, in conjunction with the aforementioned housing, defines a second compartment 21 and a fourth compartment 23, which is on the opposite side of the second compartment with respect to the second top 15b (the second and fourth compartments 21, 23 are now part of the second chamber 14b). A separation wall 40 actually separates the third and fourth compartments 22, 23. In the illustrated example, they are adjacent to each other but hydraulically separate chamber parts, i.e. the first chamber 14a and the second chamber 14b, respectively. In summary, the first apex 15a of the piston separates the first chamber 14a into first and third pump sections 20, 22 which are in fact on either side of the first apex and which change in volume as the position of the first apex changes within the first chamber, while the second apex 15b of the piston separates the second chamber into second and fourth pump sections 21, 23 which are on either side of the second piston apex and which change in volume as the position of the second apex changes within the second chamber.

[0116] In the embodiment shown, the pump 13 has a piston 15, possibly including a third top 15c, rigidly connected to a piston rod 15d and arranged opposite the first top (indeed, in the embodiment shown, the pump 13, and thus the piston 15 and the housing 14, are of symmetrical construction, the second top being located in the middle of the piston, between the first and third tops). The housing 14 also defines a third chamber 14c in which the third top 15c operates, and divides the third chamber into fifth and sixth compartments 24 and 25. The sixth compartment 25 is separated from the second compartment 21 by a further separating wall 41, for example adjacent to the second compartment 21 and through which the piston rod 15d flows in a liquid-tight manner, and the fifth compartment 24 is adjacent to the sixth compartment 25 and opposite the first compartment 20.

[0117] The first compartment 20 can be placed in fluid communication with the first part 2a of the closed circuit 2, extending downstream of the pump 13 and upstream of the evaporator 3, for delivering the working fluid in liquid state to the evaporator 3. For example, the first compartment 20 can provide an outlet passage opening to which a supply pipe 30 in the first part 2a of the circuit 2 is connected. The first compartment 20 can also be connected with the third part 2c of the closed circuit 2. For example, the first compartment 20 can provide an inlet passage opening connected to a supply pipe 31 in the third part 2c of the circuit 2, upstream of the pump 13, for receiving the working fluid in liquid state coming from the condenser 16, more precisely from the lower section 17a of the tank 17. More specifically, the first compartment can be selectively configured into a corresponding first operating state ( FIG. 1 ) in which it is in fluid communication with the supply pipe 30 and thus with the first portion 2 a of the closed circuit 2, as well as into a corresponding second operating state ( FIG. 2 ) in which it is in fluid communication with a supply pipe 31 in the third portion 2 c of the closed circuit 2 upstream of the pump 13 to receive working fluid in liquid state from the tank 17.

[0118] The second compartment 21 can be placed in fluid communication with the second part 2b of the closed circuit 2 by a supply pipe 32 for receiving the working fluid in gaseous state produced by the evaporator 3 or by a supply pipe 33 with the upper area 17b of the tank for discharging the working fluid in the tank. More specifically, the second compartment 21 can be selectively configured in a corresponding first operating state (FIG. 1) in which it is in fluid communication with the second part 2b of the closed circuit 2 (via the supply pipe 32) as well as in a corresponding second operating state (FIG. 2) in which it is in fluid communication with the third part 2c of the closed circuit 2 (via the supply pipe 33) for discharging the working fluid in gaseous state into the third part, in particular the tank 17.

[0119] According to one aspect of the invention, the pump 13 is configured and controlled by the equipment such that the first compartment 20 is in a corresponding first operating state when the second compartment 21 is also in a corresponding first operating state, and the first compartment 20 is in a corresponding second operating state when the second compartment 21 is also in a corresponding second operating state. In this way, the pressurized gas generated by the evaporator 3 coming from the second part 2b is therefore at high pressure (e.g., typically 5 to 10 bar, about 20 to 25 bar higher than the pressure of the liquid or gas in the tank 17) and, due to the larger size of the second piston 15b, tends to expand the second pump compartment and, as a result, cause a reduction in the volume of the first chamber, which forces the liquid working fluid to the evaporator. In fact, by means of the piston 15 and the tops 15a and 15b described above, the pump 13 is configured to coordinate the change in the internal volumes in the first and second compartments. In other words, the introduction of working fluid in gaseous state from the second part 2b of the closed circuit into the second compartment 21 causes a movement of the second apex (towards the right in FIG. 1) and an increase in the volume of the second compartment itself, which in turn causes a corresponding movement of the first apex (also towards the right in FIG. 1, with an equal stroke), thus decreasing the volume of the first compartment 20 and displacing the working fluid in liquid state from the first compartment to the evaporator 3.

[0120] Thanks to this solution, it is possible to utilize a (relatively small in practice) part of the thermal energy of the hot and high pressure gas present in the second part 2b of the circuit for pumping the working fluid in the liquid state, thus significantly increasing the cycle efficiency without utilizing any electrical energy and thus improving the cycle efficiency.

[0121] As mentioned above, according to one embodiment, the first and second tops are connected to each other. In particular, in the non-limiting embodiment of Fig. 1 and Fig. 2, the first and second tops 15a and 15b are rigidly connected to each other by the rod 15d, so that they move back and forth at the same time. This means that when the first section and the second section are in their corresponding first working states, the working fluid in gaseous state generated by the evaporator 3 flows into the second section 21, causing the second top 15b of the piston to move toward the first section, and the first top 15a moves and determines that the working fluid in liquid state is discharged from the first section 20 and sends it toward the evaporator 3.

[0122] In the embodiment shown, the pump 13 has a piston 15 possibly including a third top 15c. The third top 15c is rigidly connected to a rod 15d and is located opposite the first top, giving the pump 13, and thus the piston 15 and the housing 14, a symmetrical structure, with the second top located in the middle of the piston between the first and third tops. The third top operates in a third chamber 14c and divides it into a fifth compartment 24 and a sixth compartment 25.

[0123] In any currently preferred solution, the third compartment 22 is in fluid communication with the third part 2c of the closed circuit 2 upstream of the pump 13. In particular, the third compartment 22 is placed in fluid communication with the upper section 17b of the recovery tank by a supply pipe 34 in order to receive or expel working fluid in gas phase, depending on whether the piston 15 is moving in a first direction (e.g., towards the right with reference to FIG. 1 ), which determines the expulsion of liquid working fluid from the first compartment 20, or in a second direction (e.g., towards the left with reference to FIG. 2 ), which is opposite to the first direction, by drawing working fluid in liquid state into the first compartment 20. The gas from the tank 17 is supplied to the third compartment, and the absence of hot gas (e.g., from part 2b) prevents the liquid from overheating in the first compartment, and therefore the formation of gas bubbles during pumping. Similarly, the sixth compartment 26 (if present) is in fluid communication with the third part 2c of the closed circuit 2 upstream of the pump 13. In particular, the sixth compartment 22 is placed in fluid communication with the upper section 17b of the recovery tank by a supply pipe 34 (or other supply pipe) in order to receive or discharge the working fluid in gas phase, depending on whether the piston 15 is moving in a corresponding first direction (e.g. towards the right with reference to FIG. 1 ) resulting in the discharge of the liquid working fluid from the sixth compartment 25, or in a second direction opposite to the first direction (to the left with reference to FIG. 2 ) for drawing the working fluid in the liquid state into the sixth compartment 25. Again, the gas from the tank 17 is supplied to the third compartment (and possibly the sixth compartment) and is not hot gas, thereby preventing the liquid from overheating in the first compartment (and the fifth compartment, if present) and thus the formation of gas bubbles during pumping.

[0124] Alternatively, in a currently less preferred solution, the third section 22 (and, if present, the sixth section 25) can be selectively connected to the second part 2b of the circuit when the first section 20 (or, if present, the fifth section 24) is in a first operating state and pushing liquid to the evaporator 3, or the third section 22 (and, if present, the sixth section 25) can be selectively connected to the third part 2c of the circuit 2 when the first section (or, if present, the fifth section) is in a second operating state and drawing liquid from the third part 2c of the circuit 2.

[0125] Finally, similar to the second compartment 21, the fourth compartment 23 can be selectively configured in a corresponding first operating state in which it is in fluid communication with the second part 2b of the closed circuit 2, for example via a supply pipe 32 (by means of an intervening valve assembly, as seen in the state shown in FIG. 2 described below), and in a corresponding second operating state in which it is in fluid communication with the third part 2c of the closed circuit 2, upstream of the pump 13, for example via a supply pipe 33 leading to the upper section 17b of the recovery tank 17 (by means of an intervening valve assembly, as seen in the state shown in FIG. 1 described below), in order to discharge the working fluid in gaseous state to the tank.

[0126] 1 and 2, the pump 13 is driven such that the first compartment is in the first operating state when the second compartment is in its first operating state and the fourth compartment is in the corresponding second operating state. Furthermore, the pump 13 is driven such that the first compartment is in the second operating state when the second compartment is in its second operating state and the fourth compartment is in the corresponding first operating state. The third compartment is always kept in the same operating state as the tank 17, as the case may be, as described above.

[0127] If the third top 15c and the third chamber 14c are present in the pump 13 (as in Figs. 1 and 2), they are in fact dimensioned to fit the first top 15a and the first chamber 14a, respectively. When the first compartment 20 is in its first operating state and pumps liquid to the second part 2b, the fifth compartment is in its second operating state and they are connected to the circuit 2 so as to draw liquid from the third part 2c (specifically from the tank 17 - see Fig. 1), for example via the supply pipe 35. Similarly, when the first compartment 20 is in its second operating state, the fifth compartment 24 is in its first operating state (see Fig. 2) forcing liquid to the second part 2b of the circuit, for example via the supply pipe 30' connected to the evaporator 3 in the same way as the supply pipe 30.

[0128] As will be appreciated by those skilled in the art, a variety of systems can be provided to drive the pump 13 and provide the various compartment operating states as described above. In the non-limiting example shown in Figures 1 and 2, the installation is required to include at least one valve assembly 50 in communication with the pump 13 and configured as follows: · selectively placing the first section 20 of the pump in a corresponding first or second operating state; Selectively placing the second section 21 of the pump in a corresponding first or second operating state, specifically, placing the first section 21 of the pump in a corresponding first operating state when the second section 20 of the pump is also in a corresponding first operating state, and placing the first section 20 of the pump in a corresponding second operating state when the second section 21 of the pump is also in a corresponding second operating state. The fourth section 23 is selectively placed in a corresponding first or second operating state, specifically, when the second section (and thus also the first section) is in the corresponding first operating state, the fourth section 23 is placed in the corresponding second operating state, and when the second section (and thus also the first section) is in the corresponding second operating state, the fourth section is placed in the corresponding first operating state. If the fifth compartment 24 is present, the fifth compartment 24 is placed in its second operating state when the first compartment 20 is in its first operating state, and the fifth compartment 24 is placed in its first operating state when the first compartment 20 is in its second operating state (this is for pumping working fluid to the evaporator 3 on both the one-way and the opposite-way strokes of the piston 13).

[0129] In detail, the valve assembly 50 illustrated in Figures 1 and 2 includes a first check valve 51, which may be physically carried by the body of the pump 13 (for example, also directly associated with the outlet opening of the first compartment), i.e. operates in the first part 2a of the closed circuit (for example, on the supply pipe 30) to allow the working fluid in liquid state leaving the first compartment 20 to be supplied to the evaporator 3 (while preventing the fluid from flowing back into the first compartment). For example, the valve assembly 50 also includes a second check valve 52, which may be physically carried by the body of the pump and may be directly associated for example with the inlet opening of the first compartment 20 (for example, on the supply pipe 31), to allow the working fluid in liquid state from the third part 2c of the closed circuit (in particular the tank 17) to enter the first compartment during the filling phase of the first compartment with the working fluid. The valve assembly 50 shown in Figures 1 and 2 also includes a third non-return valve 54, which may be physically carried by the body of the pump 13 (for example directly associated with the outlet opening of the fifth compartment) and which operates in the first part 2a of the closed circuit (for example on the supply pipe 30') to allow the working fluid in liquid state to flow outside the fifth compartment to the evaporator 3 (while preventing the fluid from flowing back towards the fifth compartment). The valve assembly 50 also includes, for example, a fourth non-return valve 55, which may be physically carried by the body of the pump and which may be directly associated with the inlet opening of the fifth compartment 24 (for example placed on the supply pipe 35) and which operates in the third part 2c of the closed circuit to allow the working fluid in liquid state from the third part 2c (in particular the tank 17) to flow into the fifth compartment during the phase of filling the fifth compartment with working fluid.

[0130] The valve assembly 50 may also provide a selector switch 53 having at least four ways and two positions that can be selectively placed in a first position (FIG. 1) or a second position (FIG. 2). In the first position, the selector switch 53 places the fourth section 23 in a corresponding second operating state (i.e., in fluid communication with the supply pipe 33) and simultaneously places the second section 21 in a corresponding first operating state (i.e., in fluid communication with the supply pipe 32; see FIG. 1). In the second position, the selector switch 53 places the fourth section 23 in a corresponding first operating state (i.e., in fluid communication with the supply pipe 32) and simultaneously places the second section in a corresponding second operating state (i.e., in fluid communication with the supply pipe 33). In effect, the selector switch 53 alternately places the second or fourth compartment in communication with the working fluid in gaseous state present in the supply line 32 and thus the second part 2b of the circuit 2, or with the gas exhaust supply line 33 to the tank 17. The selector switch 53 may also include a third position in which the switch closes the fluid inlets and outlets from both the fourth and second compartments, effectively shutting off the pump 13 (although in the embodiment of Figures 1 and 2 such a third position is provided but not selected).

[0131] Adjustment of the selector switch 53, and therefore switching between the various positions described above, can be accomplished by an electronic, electromechanical, or fully mechanical control system.

[0132] For example, the control unit 100 may send a command to the selector switch to position the selector switch in one of the above-mentioned positions. For example, an end-of-stroke sensor 60 associated with the pump 13 may detect when the piston (15) reaches a corresponding end-of-stroke position and issue a corresponding command signal to the control unit 100. The control unit may be configured to command the selector to switch from the first position to the second position based on a signal from the end-of-stroke sensor 60. Alternatively, the end-of-stroke sensor 60 may directly command the selector switch 53 to move between the first and second positions, or vice versa.

[0133] As already mentioned, the control unit 100 can also be configured to control the valve assembly 50, in particular the selector switch 53 associated with the pump 13, to appropriately connect or hydraulically isolate the pump itself from the circuit 2 depending on the level detected by the sensor 17c and / or depending on the level detected by the level sensor 3c operating in the evaporator 3. For example, if the level detected by the level sensor 3c indicates a high liquid level, the control unit can be configured to deactivate the pump, for example by switching the selector switch to the third hydraulic lock position. Furthermore, the control unit can be configured to restart the pump and then set the selector switch to the first or second position (alternately) for pumping the fluid in liquid state to the evaporator, if the level sensor 3c indicates that the liquid level in the evaporator itself is too low. Similarly, if the level detected by the level sensor 17c indicates a high liquid level, the control unit can be configured to activate the pump, for example by switching the selector switch from the third hydraulic lock position alternately to the first and second positions. Furthermore, the control unit may be configured to stop the pump 13 and then set the selector switch to the third operating position if the level sensor 17c indicates that the liquid level in the tank 17 is too low.

[0134] Where the level sensor 3c or 17c is a mechanical device such as a float, the device may be kinematically connected to a selector switch 53 to control movement towards or away from the third position and whether or not the pump isolates itself from the circuit 2 depending on the level sensed by the sensor 3c or 17c, respectively.

[0135] Finally, in a further alternative, the pump 13 can be controlled by the control unit on a time basis which simply determines the switching of the selector switch at predetermined regular intervals.

[0136] The embodiment shown in FIGS. 3 and 4 3 and 4, an embodiment is shown in which the pump 13 comprises a housing 14 that defines at least one chamber 14a. In the housing 14, a piston 15 with a first and a second top 15a, 15b operates and is slidably accommodated in the chamber 14a. In certain cases, the first and second tops 15a and 15b are connected by a rod extending laterally therefrom, or by another rigid body 15d. As can be seen in Figs. 3 and 4, the piston 15 together with the first and second tops 15a, 15b moves back and forth in the housing 14 along a given axis X and also moves back and forth in the chamber 14a. The chamber 14a has a prismatic, particularly preferably cylindrical, shape, and the first and second tops also have a polygonal or preferably circular cross section (perpendicular to the axis X) in order to be fluid-tight in the chamber 14a, and therefore have a contour that fits against the inner surface of the respective chamber.

[0137] The first apex 15a of the piston, in conjunction with the housing 14, defines a first compartment 20. Similarly, the second apex 15b, in conjunction with the housing, defines a second compartment 21. In summary, the first apex 15a and the second apex 15b define compartments 20 and 21, whose volumes change as the position of the piston 15 changes.

[0138] The first compartment 20 may be placed in fluid communication with the first part 2a of the closed circuit 2, extending downstream of the pump 13 and upstream of the evaporator 3, in order to deliver the working fluid in liquid state to the evaporator 3. For example, the first compartment 20 may provide an outlet passage opening to which a supply pipe 30 in the first part 2a of the circuit 2 is connected. The first compartment 20 may also be connected to a third part 2c of the closed circuit 2. For example, the first compartment 20 may provide an inlet passage opening connected to a supply pipe 31 in the third part 2c of the circuit 2, upstream of the pump 13, in order to receive the working fluid in liquid state coming from the condenser 16, more precisely from the lower section 17a of the tank 17. More specifically, the first compartment can be selectively configured into a corresponding first operating state (FIG. 3) in which it is in fluid communication with the supply pipe 30 and thus the first part 2a (rather than the third part 2c) of the closed circuit 2, and into a corresponding second operating state (FIG. 4) in which it is in fluid communication with the supply pipe 31 in the third part 2c of the closed circuit 2 upstream of the pump 13 to receive working fluid in liquid state from the tank 17 (rather than from the first part 2).

[0139] The second compartment 21 can be placed in fluid communication with the second part 2b of the closed circuit 2, for example by a supply pipe 32, for receiving the working fluid in gaseous state produced by the evaporator 3, or in fluid communication with the third part 2c, in particular the upper section 17b of the tank, for example by a supply pipe 33, for discharging the working fluid into the tank itself. More specifically, the second compartment 21 can be selectively configured in a corresponding first operating state (FIG. 3) in which it is in fluid communication with the second part 2b of the closed circuit 2 (via the supply pipe 32), and in a corresponding second operating state (FIG. 4) in which it is in fluid communication with the third part 2c of the closed circuit 2 (for example by the supply pipe 33) for discharging the working fluid in gaseous state in the third part and in particular the tank 17.

[0140] According to one aspect of the invention, the pump 13 is configured and controlled by the equipment such that the first compartment 20 is in a corresponding first operating state when the second compartment 21 is also in a corresponding first operating state, and the first compartment 20 is in a corresponding second operating state when the second compartment 21 is also in a corresponding second operating state. In this way, the pressurized gas generated by the evaporator 3 from the second part 2b, which is at a high pressure (e.g., 5 to 10 bar, typically 20 to 25 bar higher than the pressure of the working fluid in the tank 17) entering the second compartment of the pump, tends to equalize the pressure in the first compartment. By the piston 15 and the tops 15a, 15b described above, the pump 13 is configured such that the variations in the internal volumes of the first and second compartments are coordinated with each other. In other words, a small force (enough to overcome friction) exerted by the drive member 70 associated with the pump 13 is sufficient to cause a displacement of the piston 15, which in turn causes a movement of the second apex 15b (towards the right in FIG. 3) in the second compartment 21, accompanied by an increase in the volume of the second compartment itself due to the inflow of working fluid in gaseous state from the second part 2b of the closed circuit, which in turn causes a corresponding movement of the first apex 15a (also towards the right in FIG. 3), thereby decreasing the volume of the first compartment 20 and displacing the working fluid in liquid state from the first compartment to the evaporator 3.

[0141] This solution makes it possible to utilize a (relatively small in practice) portion of the thermal energy of the hot, high-pressure gas present in the second part 2b of the circuit to drive the pumping of the working fluid.

[0142] As mentioned in the embodiment of Figs. 3 and 4, the pump 13 includes a drive member 70. The drive member 70 can be optionally an electric motor, or a hydraulic motor, or an electric actuator, or a hydraulic actuator, or a pneumatic actuator. The drive member 70 is operable on the piston 15 to determine a forward or backward movement along a given stroke in the housing with very low energy consumption (e.g., electrical consumption). For example, Figs. 3 and 4 show the drive member 70 connected to a pinion 71 acting on a rack 72 carried by the piston 13 to determine the forward or backward movement of the piston itself along the working stroke, thereby pumping the liquid working fluid to the evaporator. Other connections can be provided between the member 70 and the piston 11. The control unit 100 can control the drive member 70 in one direction or the other by commanding a reversal of movement based on a signal from one or more end-of-stroke sensors 60 carried by the pump and communicatively connected to the unit 100, or based on a predetermined time interval.

[0143] Also in the embodiment of Figures 3 and 4, a valve assembly 50 is provided in communication with pump 13 and is configured as follows. Selectively placing a first section of the pump in a corresponding first or second operating state. Selectively placing a second section of the pump in a corresponding first or second operating state, specifically, placing the first section in the corresponding first operating state when the second section is in the corresponding first operating state, and placing the first section in the corresponding second operating state when the second section is in the corresponding second operating state.

[0144] The valve assembly 50 may, for example, comprise a first check valve 51, which may be physically carried by the body of the pump 13 (for example also directly associated with the outlet opening of the first compartment) and thus actuated on the first part 2a of the closed circuit (for example located on the supply pipe 30) to allow the working fluid in liquid state to be supplied from the first compartment to the evaporator 3 (while preventing the fluid from flowing back into the first compartment). The valve assembly 50 may, for example, also comprise a second check valve 52, which may be carried by the body of the pump and thus also directly associated with the inlet opening of the first compartment 20 and thus actuated on the third part 2c of the closed circuit (for example on the supply pipe 31) to allow the working fluid in liquid state from the third part 2c (in particular from the tank 17) to enter the first compartment during the phase of filling the first compartment with working fluid.

[0145] The valve assembly 50 may also comprise a third non-return valve 56, which may be physically carried by the body of the pump 13 (for example directly associated with the inlet opening of the second compartment), i.e. operating on the second part 2b of the closed circuit (for example the supply pipe 32) to allow the working fluid in gaseous state produced by the evaporator 3 to be fed to the second compartment (while preventing the fluid from flowing back to the evaporator). The valve assembly 50 may also comprise a fourth non-return valve 57, which may be physically carried by the body of the pump, for example directly associated with the outlet opening from the second compartment 21, i.e. operating on the third part 2c of the closed circuit (for example the supply pipe 33) to allow the working fluid in gaseous state to flow outside the second compartment, into the third part 2c (in particular towards the tank 17), during the phase of discharging the working fluid from the second compartment.

[0146] Alternatively, the valve assembly 50 can include a selector switch, e.g., a four way, two position switch (or other valve selector) controlled by the unit 100 to effect positioning of the first and second compartments under the operating conditions described above.

[0147] In the above examples, a pump using a piston with multiple tops has been described, but instead of the pistons, membrane plates or thin films (acting as tops and defining the various compartments) kinematically connected to each other, having compartments operating as shown above and capable of ensuring a similar pump function as described above, can be used.

[0148] Also, in the above embodiment, a pump using a reciprocating piston has been described, but this does not exclude the possibility of using a "rotating piston" type.

[0149] Method for generating electrical and / or mechanical energy The invention also concerns a method of using one of the above mentioned installations or an installation according to any one of the appended claims for converting thermal energy into mechanical or electrical energy, the method comprising the step of circulating a working fluid to which motion is imparted by a pump 13. The working fluid forced by the pump 13 reaches an evaporator 3 which heats the working fluid by means of a high temperature source H until it evaporates.

[0150] The method may include a pre-heating step of the working fluid using a fuel saver or a third heat exchanger 18. For example, this pre-heating step allows the working fluid to be heated without evaporating it. The heat used for pre-heating is extracted from the expanded gas leaving the expander 4.

[0151] Following the evaporation stage, the working fluid in gaseous state reaches the expander 4, where it expands and rotates the motor shaft 11, generating mechanical energy that can be used directly. In detail, as a result of this expansion, the piston 5 of the expander is moved in a known manner, alternating (in a reciprocating expander) or rotational (in a rotary expander), thus rotating the shaft 11, which generates mechanical energy that can be used directly, for example, if the shaft 11 is connected to a user device or system. Alternatively, the shaft 11 can be connected to a power generation device 12 to generate electricity that can be appropriately stored, distributed to the power grid, or immediately used. The gas flow leaving the expander 4 then reaches the hot side of the fuel economizer 18, if present, and then proceeds to the condenser 16, where the fluid is condensed and then pumped to a tank 17.

[0152] The tank 17 is in fluid communication with the pump 13, which draws working fluid directly from the lower section 17a of the tank and circulates it back to the circuit. More specifically, the tank 17 is interposed between the condenser 16 and the pump 13 and allows the accumulation of working fluid in liquid form. In this state, the tank 17 ensures that the pump 13 draws in liquid whilst preventing air bubbles from being drawn in, thus ensuring a continuous supply of liquid.

[0153] In the case of the embodiment of figures 1 and 2, the pumping of liquid is carried out as follows: starting from, for example, the piston 15 of the pump 13 in an end-of-stroke position and moving in one of its strokes (for example from left to right as shown in figure 1) to the opposite end of the stroke, the second section 21 of the pump receives pressurized gas from the supply pipe 32, i.e. from the second part 2b of the closed circuit 2. Due to the larger cross-sectional area of ​​the second top 15b compared to the first top 15a, the piston is moved in such a way that, at the time of discharge, the second top pushes the fluid in gaseous state present in the fourth section 23 towards the tank 17, while the first top 15a pushes the working fluid in liquid state present in the first section 20 towards the evaporator 3, in particular via the supply pipe 30. At this stage, the fluid in gaseous state from the upper section 17b of the tank is simultaneously filled into the third chamber 22, which is preferably always in fluid connection with the upper section of the tank. 1 and 2, it is also provided that the third top 15c moves into the third chamber 14c to increase the volume of the fifth compartment 24, which draws in gaseous fluid from the lower area 17a of the tank 17, for example by means of a supply pipe 35. At the same time, the gaseous fluid present in the sixth compartment 25 is discharged into the upper area 17b of the tank, since the sixth compartment is preferably in constant fluid communication with the tank 17 itself.

[0154] When the end of the stroke (the right end of the stroke as shown in FIG. 1) is reached, the movement of the piston 15 is reversed (as already explained, for example by commanding the selector switch 53 to move from the position of FIG. 1 to the position of FIG. 2) and the first top 15a moves to increase the volume of the first compartment 20, then drawing the working fluid in liquid state into the first compartment 21 (see FIG. 2). At the same time, the third top 15c (if present) pushes the working fluid contained in the fifth compartment towards the evaporator 3, for example via the supply pipe 30'. At this stage, according to the appropriate operation of the selector switch (FIG. 2), the fourth compartment 23 is connected to the second part 2b of the circuit and receives the fluid in gaseous state and at high pressure, produced by the evaporator. Due to the larger cross-sectional area of ​​the second top 15b compared to the first and third tops, the fluid entering the fourth compartment pushes the second top 15b in the opposite direction to that of FIG. 1 so as to gradually reduce the volume of the second chamber 21, at this stage discharging the gaseous fluid into the upper area 17b of the tank 17. At the same time, as mentioned above, this movement of the piston 15 results in the pumping of the gaseous fluid contained in the fifth compartment 24 (if present) towards the expander 3. At the described stage (FIG. 2), the gaseous fluid present in the third chamber 22, which is preferably always in fluid communication with the upper area of ​​the tank, is discharged into the tank. At the same time, the gaseous fluid from the upper area 17b of the tank is received in the sixth compartment 25, since the sixth compartment is preferably always in fluid communication with the tank 17 itself.

[0155] During the steps described, check valves 51, 52, 54, and 55 allow fluid movement in only one direction as follows. Valve 51 allows the supply of fluid in liquid state from the first compartment 20 to the evaporator 3 but prevents the return of working fluid from the evaporator to the first compartment 20 . The second valve 52 allows the supply of working fluid in liquid state from the tank 17 to the first compartment 20 but prevents the drainage of fluid from the first compartment 20 to the tank 17. The third valve 54 allows the flow of working fluid in liquid state from the fifth compartment 24 to the evaporator 3 but prevents the return of working fluid from the evaporator to the fifth compartment 24. Finally, the valve 55 allows the supply of working fluid in liquid state from the tank 17 to the fifth compartment 24 but prevents the drainage of fluid from the fifth compartment 24 back to the tank 17.

[0156] In the case of the embodiment of figures 3 and 4, the pumping of liquid is performed as follows: starting from a state in which the piston 15 of the pump 13 is in an end-of-stroke position and moves in one of its strokes (for example from left to right as shown in figure 3) to the opposite end of the stroke, the second section 21 of the pump receives pressurized gas from the supply pipe 32, i.e. from the second part 2b of the closed circuit 2. Due to the actuation of the drive member 70 and due to the pressure in the first section 20 not being higher than the pressure in the second section, the piston moves in such a way that the first top 15a pushes the working fluid in liquid state present in the first section 20 towards the evaporator 3, in particular through the supply pipe 30.

[0157] When the end of the stroke (the right end of the stroke as shown in FIG. 3) is reached, the movement of the piston 15 is reversed (e.g. by a command to reverse the movement of the drive member 70, as described above), and the first apex 15a moves to increase the volume of the first compartment 20, which then draws the working fluid in liquid state coming from the lower area 17a of the tank 17 into the first compartment (see FIG. 4). At the same time, the fluid in gaseous state in the second compartment 21 is expelled into the upper area 17b of the tank 17.

[0158] During the steps described, check valves 51, 52, 56, and 57 allow fluid movement in only one direction as follows. Valve 51 allows the supply of fluid in liquid state from the first compartment 20 to the evaporator 3 but prevents the return of working fluid from the evaporator to the first compartment 20 . The second valve 52 allows the supply of working fluid in liquid state from the tank 17 to the first compartment 20 but prevents the drainage of fluid from the first compartment 20 to the tank 17. · The third valve 56 allows the flow of working fluid in gaseous state from the evaporator 3 to the second compartment, but prevents the return of working fluid from the second compartment 21 to the evaporator. Finally, a fourth valve 57 allows the discharge of working fluid in gaseous state from the second compartment 21 to the tank 17, but prevents fluid from returning from the tank to the second compartment 21.

[0159] The solution described and claimed makes it possible to utilize part of the energy in the working fluid to pump or assist the fluid in the closed circuit 2, thereby increasing the overall efficiency of the cycle.

[0160] Furthermore, pumps of the type with piston 13 described above are suitable for reliable use since they are simple in design, have no sealing problems and can operate at high pressure jump values ​​while also requiring little maintenance.

[0161] It should also be noted that the present installation and method are completely, or nearly completely, energy self-sufficient.

[0162] Furthermore, by properly driving the pump 13, the problem of cavitation can be avoided altogether.

Claims

Claim 1 A facility (1) for converting thermal energy into electrical and / or mechanical energy, comprising a closed circuit (2) for circulating at least one working fluid, at least one pump (13) operating within the closed circuit (2) and designed to circulate the working fluid within the closed circuit, at least one evaporator (3) operable on the closed circuit (2), configured to receive heat from a high-temperature source (H) and heat the working fluid to cause a transition from a liquid state to a gaseous state, at least one, optionally positive-displacement, expander (4) operating downstream of the evaporator (3) within the closed circuit (2) and configured to receive the working fluid flowing in a gaseous state, at least one condenser (16) operable on the closed circuit (2) downstream of the expander (4) and upstream of the pump (13), configured to condense the working fluid by effecting a transition of the working fluid from the gaseous state to the liquid state, wherein the pump (13) has at least a first compartment (20) arranged in fluid communication with a first portion (2a) of the closed circuit (2) extending downstream of the pump (13) and upstream of the evaporator (3) for sending the working fluid in a liquid state to the evaporator (3), and a second compartment (21) arranged in fluid communication with a second portion (2b) of the closed circuit extending downstream of the first portion (2a) and upstream of the expander (4) for receiving the working fluid in a gaseous state generated by the evaporator (3). Facility (1). Claim 2 The facility according to claim 1, wherein the pump is configured such that when the working fluid in a gaseous state arriving from the second portion (2b) flows into the second compartment (21), an increase in the volume of the second compartment (21) is determined, which in turn prompts a decrease in the volume of the first compartment (20), causing a movement of the working fluid in a liquid state towards the evaporator (3). Claim 3 A corresponding first operating state in which the first compartment (20) is in fluid communication with the first part (2a) of the closed circuit (2), and a corresponding second operating state in which the first compartment (20) is in fluid communication with a third part (2c) of the closed circuit (2) that extends downstream of the condenser (16) and upstream of the pump (13) in order to receive the working fluid in liquid state coming from the condenser (16), the first compartment (20) can be selectively configured, A corresponding first operating state in which the second compartment (21) is in fluid communication with the second part (2b) of the closed circuit (2), and a corresponding second operating state in which the second compartment (21) is in fluid communication with the third part (2c) of the closed circuit (2) upstream of the pump (13) in order to discharge the working fluid in gaseous state to the third part (2c), the second compartment (21) can be selectively configured, The facility according to claim 2.

4. The facility according to claim 3, configured to maintain the first compartment (20) in the corresponding first operating state when the second compartment (21) is in the corresponding first operating state, and to maintain the first compartment (20) in the corresponding second operating state when the second compartment (21) is in the corresponding second operating state.

5. Comprising at least one recovery tank (17) operating in the third part (2c) of the closed circuit (2) and interposed between the condenser (16) and the pump (13), the recovery tank (17) receiving the working fluid from the condenser (16) and configured to contain the working fluid in liquid state in a state balanced with the working fluid in gaseous state, The first compartment (20) is in fluid communication with an area of the recovery tank (17), particularly the lower area (17a) of the recovery tank where the working fluid in liquid state is present, in order to receive the working fluid in liquid state from the recovery tank in the corresponding second operating state, The second compartment (21) is in fluid communication with an area of the recovery tank (17), particularly the upper area (17b) of the recovery tank where the working fluid in gaseous state is present, in order to discharge the working fluid in gaseous state to the recovery tank in the corresponding second operating state. The facility according to any one of claims 1 to 4.

6. The pump (13) comprises a housing and at least one piston operating within the housing, The equipment according to any one of claims 1 to 4, wherein the piston has a first top portion that cooperates with the housing to define the first compartment (20) and a second top portion that cooperates with the housing to define the second compartment (21).

7. The first and second top portions are connected to each other, particularly rigidly connected to each other, so that when each of the first compartment (20) and the second compartment (21) is in a corresponding first operating state, the gaseous working fluid generated by the evaporator (3) and flowing into the second compartment (21) causes the movement of the second top portion of the piston, and also moves the first top portion, discharging the liquid working fluid from the first compartment (20) and sending it towards the evaporator (3) is also determined, when each of the first compartment (20) and the second compartment (21) is in a corresponding second operating state, the liquid working fluid flowing into the first compartment (20) causes the movement of the first top portion of the piston, and also moves the second top portion, discharging the gaseous working fluid from the second compartment (21) and sending it towards the third part (2c) of the closed circuit (2) that extends downstream of the condenser (16) and upstream of the pump (13) is also determined, the equipment according to claim 6.

8. The pump comprises a drive member (70) that acts on the piston to move the piston back and forth along a predetermined stroke within the housing, the drive member (70) being optionally an electric motor, or a hydraulic motor, or an electric actuator, or a hydraulic actuator, or a pneumatic actuator, the housing defines at least first and second working chambers that are hydraulically separated from each other, each defining a corresponding volume that can be filled with the working fluid, the volume of the second chamber is larger than the volume of the first chamber, specifically, at least 1.5 times larger than the volume of the first chamber, the equipment according to claim 6.

9. The first and second chambers have equal axial extensions, i.e., equal extensions in the direction of piston movement, and have different cross-sections, The first piston top is slidably received within the first chamber, the second piston top is slidably received within the second chamber, the first and second tops optionally extend laterally with respect to the first and second tops, and are rigidly connected by a rod that penetrates a separating wall between the first chamber and the second chamber in a liquid-tight manner, and the first top has an effective cross-sectional area smaller than that of the second top. The first piston top separates the first chamber into the first section (20) and the third section (22) of the pump, and the first and third sections (22) extend on both sides of the first piston top, showing a change in volume as the position of the first top changes within the first chamber. The second piston top separates the second chamber into the second section (21) and the fourth section (23) of the pump, and the second and fourth sections (23) extend on both sides of the second piston top, showing a change in volume as the position of the second top changes within the second chamber. The facility according to claim 8.

10. The first section (20) is sequentially adjacent to the third section (22), the third section (22) is sequentially adjacent to the fourth section (23), and the fourth section (23) is sequentially adjacent to the second section (21). The facility according to claim 9.

11. The third section (22) is upstream of the pump (13) and is in fluid communication with the upper region of the recovery tank (17) where the third part (2c) of the closed circuit (2), particularly the gaseous working fluid, is present. The corresponding first operating state in fluid communication with the second part (2b) of the closed circuit (2), and in order to discharge the gaseous working fluid to the third part (2c), upstream of the pump (13), the third part (2c) of the closed circuit (2), particularly the upper region of the recovery tank (17) where the gaseous working fluid is present. The facility according to claim 9, wherein the fourth section (23) can be selectively configured to be in fluid communication and the corresponding second operating state.

12. The installation (1) is configured such that when the second section (21) is in the corresponding first operating state, the fourth section (23) is maintained in the corresponding second operating state, and when the second section (21) is in the corresponding second operating state, the fourth section (23) is maintained in the corresponding first operating state, the installation according to claim 9.

13. Associated with the pump (13), selectively setting the first section (20) of the pump (13) to the corresponding first or second operating state, selectively setting the second section (21) of the pump (13) to the corresponding first or second operating state The installation according to claim 3, comprising at least one valve assembly (50) configured to

14. When the second section (21) is in the corresponding first operating state, the first section (20) of the pump (13) is set to the corresponding first operating state, and when the second section (21) is in the corresponding second operating state, the first section (20) is set to the corresponding second operating state, the valve assembly (50) is configured as described in claim 13.

15. The valve assembly (50) is optionally a first check valve (51) operating in the first part (2a) of the closed circuit (2) to allow the working fluid in liquid state flowing out of the first section (20) to be supplied to the evaporator (3); optionally a second check valve (52) operating in the third part (2c) of the closed circuit (2) to allow the working fluid in liquid state coming from the third part (2c) to flow into the first section (20); optionally a third check valve (56) operating on a supply pipe (32) connecting the second section (21) to the second part (2b) of the closed circuit (2) to allow the working fluid in gaseous state generated by the evaporator (3) to flow into the second section (21); optionally a fourth check valve (57) operating on a further supply pipe (33) connecting the second section (21) to the third part (2c) of the closed circuit (2) to allow the working fluid in gaseous state to be discharged from the second section (21) to the third part (2c) of the closed circuit, the installation according to claim 13.

16. wherein said valve assembly (50) selectively positions said fourth compartment (23) in said corresponding first or second operating state, and wherein said valve assembly (50) is further configured such that when said second compartment (21) is in said corresponding first operating state, said fourth compartment (23) is positioned in said corresponding second operating state, and conversely, when said second compartment (21) is in said corresponding second operating state, said fourth compartment (23) is positioned in said corresponding first operating state; the installation according to claim 13.

17. wherein said valve assembly (50) optionally includes a first check valve (51) operating in said first portion (2a) of said closed circuit (2) to enable said valve assembly (50) to supply liquid operating fluid flowing out of said first compartment (20) to said evaporator (3); optionally includes a second check valve (52) operating in said third portion (2c) of said closed circuit (2) to enable liquid operating fluid arriving from said third portion (2c) to flow into said first compartment (20); and a selector switch (53) having at least four directions and two positions, said selector switch (53) setting said fourth compartment (23) in said corresponding second operating state and simultaneously setting said second compartment (21) in said corresponding first operating state in a first position, and setting said fourth compartment (23) in said corresponding first operating state and simultaneously setting said second compartment (21) in said corresponding second operating state in a second position; the installation according to claim 16.

18. comprising a level sensor (3c) associated with said evaporator (3) and / or a level sensor (17c) associated with said tank (17), a control unit (100) wherein said level sensor (3c) associated with said evaporator, which transmits at least a corresponding signal regarding the liquid level in said evaporator to said control unit (100), and said control unit (100) is configured to control or not control the operation of said pump (13) by receiving said signal and, in response to said signal, for example, by operating the positioning of said selector (53) or by activating said drive member (70) based at least on said signal. ​ The level sensor (17c) associated with the tank, which transmits at least a corresponding signal regarding the liquid level in the tank to the control unit (100), and the control unit receives the signal and, in response to the signal, for example, by operating the positioning of the selector (53) or by actuating the drive member (70) based at least on the signal, controls or does not control the operation of the pump (13). The equipment according to any one of claims 1 to 4 and claims 13 to 17, comprising a control unit (100) communicably connected to at least one of the level sensors (17c).

19. The piston (15) is at least one stroke end sensor (60) associated with the pump for detecting that the piston has reached the position of the corresponding stroke end, configured to directly control the reversal of the movement of the piston, for example, by transmitting a command signal to the selector or the drive member, and / or configured to issue a corresponding command signal to the control unit (100) configured to command the reversal of the movement of the piston (15) by, for example, operating the positioning of the selector (53) or by commanding the operation of the drive member (70). Comprising a stroke end sensor (60), or The control unit (100) is configured to control the reversal of the movement of the piston (15) at a predetermined constant time interval, for example, by operating the positioning of the selector (53) or by controlling the operation of the drive member (70). The equipment according to any one of claims 1 to 4 and claims 13 to 17, including any one of them.

20. The evaporator (3) comprises at least a first heat exchanger having a side configured to receive heat from a high temperature source (H) and a side intersecting the second part (2b) of the closed circuit. The condenser (16) is on the side intersecting the cross-section of the third part (2c) of the closed circuit (2) intervening between the expander (4) and the pump (13), and interacts with the low-temperature source (C) and is configured to be able to condense the working fluid crossing the cross-section and to determine the transition from the gaseous state to the liquid state. The installation according to any one of claims 1 to 4 and claims 13 to 17 includes at least a second heat exchanger having such a side.

21. On the side intersecting the cross-section of the closed circuit intervening between the expander (4) and the condenser (16), and for determining the preheating of the working fluid in the liquid state flowing out of the pump (13) and going towards the evaporator (3), the installation according to any one of claims 1 to 4 and claims 13 to 17 includes at least a third heat exchanger (18) having a side intersecting the cross-section of the first part (2a) of the closed circuit.

22. The positive displacement expander (4) includes at least one piston (5) defining an expansion chamber (6) with a variable volume, a main shaft (11) kinematically connected to the piston (5) and configured to rotate about a main axis, and at least one valve (8) configured to selectively open and close the inlet and outlet (9, 10) of the expansion chamber (6), wherein the valve (8) brings about at least a state in which the working fluid flows into the expansion chamber (6), a state in which the working fluid expands in the expansion chamber (6), and a state in which the working fluid is discharged from the expansion chamber (6), and the power generation device is connected to the main shaft, and the installation according to any one of claims 1 to 4 and claims 13 to 17 is configured to implement a closed Rankine cycle.

23. A method for converting thermal energy into electrical and / or mechanical energy, comprising: installing the installation (1) according to claim 1; evaporating the working fluid in the evaporator (3); expanding the working fluid flowing out of the evaporator (3) inside the positive displacement expander (4), and as a result, generating mechanical or electrical energy by a generator (12) mechanically connected to the positive displacement expander; condensing the working fluid flowing out of the positive displacement expander (4) in the condenser (16). A step of pumping a liquid working fluid from the condenser (16) to the evaporator (3) using the pump (13). A method in which the pump uses gaseous working fluid generated by the evaporator (3), also from the evaporator (3), or from a second part (2b) of the closed circuit (2) between the evaporator (3) and the positive displacement expander (4), to pump the liquid working fluid from the condenser (16) towards the evaporator (3).

24. A method of converting thermal energy into electrical and / or mechanical energy using the installation according to claim 1.

25. A method of converting thermal energy into electrical and / or mechanical energy, comprising: A step of installing the installation (1) according to claim 1; A step of using a pump (13) to pump the working fluid in the liquid state into the closed circuit (2), the pump utilizing gaseous working fluid arriving from within the closed circuit itself for the pumping operation; A method including this.

26. The method according to claim 25, wherein the gaseous working fluid used by the pump to pump the liquid working fluid comes from a part of the circuit (2) upstream of the expander, which gaseous working fluid is used to generate mechanical and / or electrical power.

27. The method includes: Evaporating the working fluid within the evaporator (3); Expanding the working fluid flowing out of the evaporator (3) within the positive displacement expander (4), and as a result, generating mechanical or electrical energy by the generator (12) mechanically connected to the positive displacement expander; Condensing the working fluid flowing out of the positive displacement expander (4) within the condenser (16); Using the pump (13) to pump the liquid working fluid arriving from the condenser (16) to the evaporator (3); Including: The method according to claim 24, wherein the pump uses gaseous working fluid taken from the evaporator (3), from the evaporator (3) itself, or from the second part (2b) of the closed circuit (2) included between the evaporator (3) and the positive displacement expander (4), which gaseous working fluid is generated by the evaporator (3), to pump the liquid working fluid from the condenser (16) towards the evaporator (3).

28. The method includes evaporating the working fluid in the evaporator (3); expanding the working fluid flowing out of the evaporator (3) in the positive displacement expander (4), as a result of which mechanical or electrical energy is generated by the generator (12) mechanically connected to the positive displacement expander; condensing the working fluid flowing out of the positive displacement expander (4) in the condenser (16); using the pump (13) to pump the liquid-state working fluid coming from the condenser (16) to the evaporator (3); comprising; The method according to claim 25, wherein the pump uses the gaseous-state working fluid generated by the evaporator (3), taken from the evaporator (3) itself, or from the second part (2b) of the closed circuit (2) included between the evaporator (3) and the positive displacement expander (4), to pump the liquid working fluid from the condenser (16) towards the evaporator (3).

29. The method is evaporating the working fluid in the evaporator (3); expanding the working fluid flowing out of the evaporator (3) in the positive displacement expander (4), as a result of which mechanical or electrical energy is generated by the generator (12) mechanically connected to the positive displacement expander; condensing the working fluid flowing out of the positive displacement expander (4) in the condenser (16); using the pump (13) to pump the liquid-state working fluid coming from the condenser (16) to the evaporator (3); comprising; The method according to claim 26, wherein the pump uses the gaseous-state working fluid generated by the evaporator (3), taken from the evaporator (3) itself, or from the second part (2b) of the closed circuit (2) included between the evaporator (3) and the positive displacement expander (4), to pump the liquid working fluid from the condenser (16) towards the evaporator (3).

30. In the second compartment (21) of the pump, receive the pressurized gaseous working fluid from the second part (2b) of the closed circuit (2), and the second top part, in the discharge to the third part (2c) of the circuit, in particular to the tank (17), push forward the gaseous working fluid present in the fourth compartment (23), while the first top part moves the piston (15) so as to push forward the working fluid in the liquid state, which is present in the first compartment (20), to the first part (2a), in particular to the evaporator (3). When the piston (15) reaches the stroke end, reverse the movement of the piston (15) by a control device such as a selector switch (53) that moves, increase the volume of the first compartment (20), move the first top part so as to draw back the working fluid in the liquid state into the first compartment, and the fourth compartment (23), which is connected to the second part (2b) of the circuit, receives the fluid in the gaseous state and under high pressure generated by the evaporator, and the second compartment (21) discharges the gaseous working fluid to the third part (2c) of the circuit, in particular to the tank (17). The method according to any one of claims 24 to 29, including the above.

31. Receive, in the second compartment (21) of the pump, the gaseous and pressurized working fluid coming from the second part (2b) of the closed circuit 2. The first top part moves the piston (15) by operating the drive member (70) so as to push forward the working fluid in the liquid state, which is present in the first compartment (20), to the evaporator (3), and at the same time fill the second compartment (21) with the gaseous and high-pressure working fluid generated by the evaporator (3). When the piston (15) reaches the stroke end, reverse the movement of the piston (15) by a control device that reverses the movement of the drive member (70), for example, and increase the volume of the first compartment (20), draw the working fluid in the liquid state from the third part (2c) of the circuit (2) into the first compartment, and at the same time move the first top part so as to discharge the gaseous fluid from the second compartment (21) to the third part (2c) of the circuit. The method according to any one of claims 24 to 29.

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