EP4345262A1

EP4345262A1 - Method and device for transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area, and a system comprising the device

Info

Publication number: EP4345262A1
Application number: EP23188444.6A
Authority: EP
Inventors: Tomasz Grudniak
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-09-27
Filing date: 2023-07-28
Publication date: 2024-04-03
Also published as: PL442372A1

Abstract

A method of transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area, in which a working medium is in the gaseous phase or supercritical state, is characterized in that at least one working space (P) is moved and as a result of the moving the at least one working space (P) is opened at the CG stage in the high-pressure area and the working medium in the liquid phase, having a much higher density than the surrounding working medium in the gaseous phase or supercritical state, is caused to drop from this at least one working space (P), whereby the working medium in the liquid phase is replaced in the working space (P) by the working medium in the gaseous phase or supercritical state.

A device (15) for transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area, characterized in that it comprises at least:
- drum (5), driven by drive (19), rotating and arranged in housing (11, 12), in which there is at least one working space (P),
- bearing shafts (9) connected to drum (5) and arranged in housing (11, 12),
- two floating plates (6) with openings (GC, CG) arranged in housing (11, 12) and connecting working space (P) to:
- the high-pressure area upstream and downstream of the evaporator, where the working medium in the liquid phase is exchanged in the working space for the working medium in the gaseous phase or supercritical state
- the area upstream and downstream of condenser (17), where the working medium in the gaseous phase or supercritical state is exchanged in working space (P) for the working medium in the liquid phase.

A system comprising a device for transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area, an evaporator, a condenser and at least one working device characterized in that device (15) for transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area comprises at least:
-drum (5), driven by drive (19), rotating and arranged in housing (11, 12), in which there is at least one working space (P),
- bearing shafts (9) connected to drum (5) and arranged in housing (11, 12),
- two floating plates (6) with openings (GC, CG) arranged in housing (11, 12) and connecting working space (P) to:
- the high-pressure area upstream and downstream of the evaporator, where the working medium in the liquid phase is exchanged for the working medium in the gaseous phase or supercritical state
- the area upstream and downstream of the condenser (17), where in the working space (P) the working medium in the gaseous phase or supercritical state is exchanged in the working space for the working medium in the liquid phase.

Description

The subject of the invention is a method of transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area, a device implementing this method and a system comprising this device.
The invention relates in particular to the transfer of a working medium in a liquid phase from a low-pressure area to a high-pressure area in thermodynamic cycles and belongs to the field of thermodynamic cycles.
One of the transformations that can occur in thermodynamic cycles is the compression of the working medium in the liquid phase, which is normally carried out by a pump.
In the case of the most popular cycle with a phase change, i.e. the Rankine cycle, the parameter describing the importance of a pump operation for the cycle is the ratio of the power of the pump drive to the power of the working device (turbine), referred to as BWR (from English: Back Work Ratio).
In the case of the water subcritical Rankine cycle, this parameter is low, and the pump power is sometimes omitted in the cycle calculations. In ORC (Organic Rankine Cycle) cycles, which have been developing intensively in recent years, it is much higher (even up to 20%).
On the other hand, the efficiencies of liquid compression devices in small-scale ORC cycles are low.
According to the publication by Zbynek Zeleny, Vaclav Vodicka, Vaclav Novotny, Jakub Mascuch, entitled "Gear pump for low power output ORC - an efficiency analysis", the 4th International seminar on ORC Power Systems, ORC2017, September 13-15, 2017, Milan, Italy), pump efficiencies for small ORC systems are typically in the range of 7-35%, and after taking into account the efficiency of the pump drive, they are even lower.
Implementation of such a cycle without pump could allow a much more favourable (lower) BWR to be achieved.
An example of implementing a pumpless Rankine cycle has been described in the scientific literature. This is the solution presented by Naboru Yamad and Mohamed Md Nor Anuar in "Fundamental experiment of pumpless Rankine-type cycle for low temperature heat recovery", Volume 36 on Energy, Issue 2, February 2011, pages 1010-1017. This solution is based on the operation of two exchangers, each of which alternately works as a condenser and an evaporator.
In addition, US5865086A discloses a liquid circulation system in a thermodynamic cycle in which the working medium in the liquid phase is replaced in the working space by the working medium in the gaseous phase. This system works in a two-phase cycle. In the first phase, the vertical cylindrical tank is filled with a liquid by gravity (principle of communicating vessels) from the liquid tank through the check valve and an inlet of the liquid. When the liquid fills the cylindrical tank, the lower float control causes the steam and air escape valve to open, allowing steam and air to escape as the cylinder tank fills, and this is controlled by the control module. When the liquid fills the cylinder, the upper float control, with a limit switch, sends a signal to the control module, electrically closing the steam and air escape valve and opening the steam injection valve. This starts the second phase. In the second phase, the steam injected from the boiler presses downwards the surface of the liquid that has filled the cylinder. The liquid is thus pushed downwards and outwards through the orifice of outlet piping and the check valve. At the same time, the downward liquid pressure closes the check valve, preventing the additional liquid from entering. When a certain amount of liquid has been displaced from the cylinder, the lower float regulator is activated, restarting the process of filling the cylinder with liquid.
WO2011092705A2 discloses a circulation system in the thermodynamic cycle in which liquid is transferred to the evaporator without the use of a pump. There is an additional tank in the system to which steam from the evaporator is supplied, which is then reheated to achieve a pressure higher than in the evaporator. This steam then pushes the liquid out of the second additional tank, expanding until it reaches a pressure equal to the pressure in the evaporator. This steam is then expanded to the pressure downstream of the condenser and the second additional tank being filled with liquid and the cycle is repeated. The main thermodynamic cycle with a turbine, as described, operates continuously, while the secondary cycle with two additional tanks operates cyclically.
The state-of-the-art solutions outlined above are structurally complex and therefore expensive.
The document KR20150098305A discloses the use of a rotating cylinder with working spaces for transferring the working medium in the Rankine cycle. In this document, the working spaces are arranged radially with respect to the axis of rotation of the cylinder and the transfer of the working medium is carried out using centrifugal force.
Document CN2109723510A discloses a circulation system in a thermodynamic cycle without the use of a pump. The system uses two alternating evaporators which are cyclically filled and deliver compressed steam to the turbine.
The problem, the solution of which is the purpose of the present invention, is to provide a method and a device of simple construction, that will make it possible to provide a low BWR parameter of a thermodynamic cycle at low cost, and a system containing this device in which this method is implemented.
This problem has been solved by the following method and device according to the invention for transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area, and a system comprising the device in which the method is implemented.
A method of transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area, in which a working medium is in the gaseous phase or supercritical state according to the invention is characterized in that at least one working space is moved and as a result of the moving the at least one working space is opened at the CG stage in the high-pressure area and the working medium in the liquid phase, having a much higher density than the surrounding working medium in the gaseous phase or supercritical state, is caused to drop from this at least one working space, whereby the working medium in the liquid phase is replaced in the working space by the working medium in the gaseous phase or supercritical state.
Advantageously, the at least one working space filled after the CG stage with a high-pressure gas is moved and as a result of the moving the at least one working space is opened at the GC stage in a low-pressure area, in which the working medium is in the liquid phase and it is caused to raise the working medium in the gaseous phase or supercritical state, having a significantly lower density than the surrounding working medium in the liquid phase, from the working space, and to fill the working space by the working medium in the liquid phase, whereby the working medium in the gaseous phase or supercritical state is replaced in the working space by the working medium in the liquid phase.
Advantageously, the compressed working medium in the gaseous phase or supercritical state, before being replaced at the GC stage in the working space by the working medium in the liquid phase, is expanded in the expansion tank at the expansion stage RP, while the volume of the working medium in the gaseous phase or supercritical state, which after expansion exceeds the working volume, is directed to the condenser.
Advantageously, the compressed working medium in the gaseous phase or supercritical state, before being replaced at the GC stage in the working space by the working medium in the liquid phase, expands at the expansion stage RP, while the volume of the working medium in the gaseous phase or supercritical state, which after expansion exceeds the working volume, is directed to the additional condenser through a separate path than the path of the working medium in a gaseous phase or supercritical state from the working device.
Advantageously, before the expansion of the compressed working medium in the gaseous phase or supercritical state at the RP stage, the working medium is partially expanded at a driving stage NP and the additional working device is driven by this working medium.
Advantageously, the working space together with the working medium contained therein is moved between the different stages of the cycle.
Advantageously, the working space together with the working medium contained therein is moved by rotating the drum in which at least one working space is arranged.
Advantageously, at least one working space, in the form of an opening connecting the surfaces of the drum in contact with the floating plates, is moved by rotating the drum using a drive.
A device for transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area according to the invention is characterized in that it comprises at least:

a drive-driven, rotating, and housed drum, in which there is at least one working space,
bearing shafts connected to the drum and arranged in the housing,
two floating plates arranged in the housing with openings connecting the working space to:
- the high-pressure area upstream and downstream of the evaporator, where the working medium in the liquid phase is exchanged in the working space for the working medium in the gaseous phase or supercritical state
- the area upstream and downstream of the condenser, where the working medium in the gaseous phase or supercritical state is exchanged in the working space for the working medium in the liquid phase.

Advantageously, the drum is rotatably mounted between floating plates for sealing the rotating working spaces.
Advantageously, gaskets for separating different stages are arranged in the seats of the floating plates.
Advantageously, the gaskets in the floating plate seats are shaped to ensure the balance of the axial forces acting on them.
Advantageously, the openings of the two floating plates also connect the working space to the area where the working medium in the gaseous phase or supercritical state is expanded in the working space.
Advantageously, the openings of the two floating plates also connect the working space to the area where the working medium in the gaseous phase or supercritical state in the working space is expanded and performs work on the additional working device.
Advantageously, at least one workspace is an opening connecting drum surfaces in contact with the floating plates.
A system comprising a device for transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area, an evaporator, at least one condenser and at least one working device according to the invention is characterized in that the device for transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area comprises at least:

Advantageously, the openings of the two floating plates also connect the working space to the area where the working medium in the gaseous phase or supercritical state is expanded in the working space.
Advantageously, the openings of the two floating plates also connect the working space to the area where the working medium in the gaseous phase or supercritical state is expanded in the working space and performs work on the additional working device.
Advantageously, at least one working space is an opening connecting drum surfaces in contact with the floating plates.
The object of the invention is illustrated in the embodiments, without respecting geometrical proportions, in the accompanying drawing, in which

fig. 1 shows the T-s (temperature-entropy) diagram of an exemplary Rankine cycle for the working medium R600A (isobutane),
fig. 2 shows the T-s (temperature-entropy) diagram of an exemplary supercritical Rankine cycle for the same working medium R600A (isobutane),
fig. 3 shows an exploded view of the device according to the invention having one working space in the drum and two stages of the cycle,
fig. 4 shows an exploded view of the device according to the invention, which also implements a two-stage cycle, but has four working spaces in the drum,
fig. 5 shows an exploded view of the device according to the invention having four working spaces in the drum and three stages of the cycle,
fig. 6 shows an exploded view of the device according to the invention having four working spaces in the drum and four stages of the cycle,
fig. 7 shows the device according to the invention in the power plant layout in a version with two stages of the cycle,
fig. 8 shows a schematic diagram of the same system,
fig. 9 shows a schematic diagram of the system with an additional expansion stage,
fig. 10 shows a schematic diagram of the system in which, before the expansion stage, the additional working device is driven by the expansion of the working medium,
fig. 11 shows a schematic diagram of the system having an additional evaporator,
fig. 12 shows a schematic diagram of the system having an additional evaporator and an additional working device.

The invention may relate to any working medium and any thermodynamic cycle with phase change of the working medium in which it is necessary to compress the medium in the liquid phase.
For the working medium R600A (isobutane), which is classified as dry due to the shape of the saturation curve and as organic due to its low boiling point, the characteristic points of the exemplary Rankine cycle, shown in fig 1, are as follows (calculations of the parameters of the working medium at different points of the thermodynamic cycle were carried out using the REFPROP 10.0 program (NIST Reference Fluid Properties))

in the case of the system with the pump according to the state-of-the-art:
- 1A - upstream of the pump
  - P_1A=0.40472 MPa, T_1A=30°C, s_1A=1.2458 kJ/kgK, h_1A=271.24 kJ/kg,
  - ρ_1A=544.31 kg/m³
- 2A - upstream of the evaporator
  - P_2A=2.3827 MPa, T_2A= 31.05°C, s_2A=1.2458 kJ/kgK, h_2A=274.87 kJ/kg,
  - ρ_2A=547.37 kg/m³
- 3A - upstream of the working device
  - P_3A=2.3827 MPa, T_3A=110°C, s_3A=2.3785 kJ/kgK, h_3A=683.74 kJ/kg,
  - ρ_3A=72.335 kg/m³
- 4A - upstream of the condenser
  - P_4A=0.40472 MPa, T_4A=41.05°C, s_4A=2.3785 kJ/kgK, h_4A=614.99 kJ/kg,
  - ρ_4A=9.9586 kg/m³,

where: P - pressure, T - temperature, s - entropy, h - enthalpy, ρ - density of the working medium
Work performed steam: W_TA = h_3A - h_4A = 683.74 - 614.99 = 68.75 kJ/kg
Work of the pump: W_PA = h_2A - h_1A = 274.87 - 271.24 = 3.63 kJ/kg
Heat delivered: Q_DA = h_3A - h_2A = 683.74 - 274.87 = 408.87 kJ/kg

BWR for the cycle according to fig. 1 with a pump: ${BWR}_{PA} = (W_{PA} * q) / (W_{TA} * q) = W_{PA} / W_{TA} = 3.63 / 68.75 = 5.3 %$
where q - mass flow rate [kg/s]
Compressing the working medium in the liquid phase using a pump can be replaced by exchanging the medium in the gaseous phase for the medium in the liquid phase. In the claimed solution, after opening the working space P in the high-pressure and temperature area, the pressure above and below the liquid is the same.
With parameters as in the example above:

the density of the liquid after opening the working space in the high-pressure area is ρ_2A=547.37 kg/m³
the density of the gas after opening the working space in the high-pressure area is ρ_3A=72.335 kg/m³
the liquid in the working space is affected by a force that is the difference between its weight and the buoyancy force: F_2A = (ρ_2A - ρ_3A) ^∗g^∗V,

²

The liquid drops into the high-pressure area filled with the working medium in the gaseous phase or supercritical state due to its much higher density, and the working space P is filled with the working medium in the gaseous phase. This stage in the present description of the invention is denoted as CG
The working space P, in which the working medium in the gaseous phase was found, is then opened in the area upstream of the condenser and it is exchanged for the medium in the liquid phase.
With parameters as in the example above:

the density of the gas after opening the working space in the low-pressure area is ρ_4A=9.9586 kg/m³
the density of the liquid after opening the working space in the low-pressure area (point 3A) is ρ_1A=544.31 kg/m³
the gas in the working space is affected by a force that is the difference between the buoyancy force and its weight: F_4A = (ρ_1A - ρ_4A) ^∗g^∗V,

²

The gas flows to the surface of the liquid in the low-pressure area due to the much lower density, and the working space (P) is filled with the working medium in the liquid phase.
This stage in the present description of the invention is denoted as GC.
Due to the directions of the acting forces, the device can operate vertically or with slight deviations from the vertical.
The simplest cycle consists of the above two stages (CG and GC) being carried out alternately. Within this cycle, a large amount of the working medium (working volume in the liquid phase) is introduced into the thermodynamic cycle and a small amount of the medium (working volume of the compressed medium in the gaseous phase) is withdrawn. The proportions of these amounts change depending on the parameters (pressure, temperature) at different points of the thermodynamic cycle.
In the example according to fig. 1, the working medium at point 1A upstream of the pump (in the case of the state of the art) or upstream of the device according to the invention has a density of 544.31 kg/m³, and at point 3A its density is 72.335 kg/m³.
Thus, exchanging the medium in the working space P (e.g. 1 m³) using the device according to the invention, 544.31 kg of the working medium in the liquid phase is introduced to the evaporator, and 72.335 kg of the working medium in the gaseous phase is withdrawn from it. This means that in the exemplary cycle the working medium in the liquid phase in amount (544.31 - 72.335) / 544.31 * 100 = 86.7% is effectively delivered from the working space P to the evaporator and this part of the delivered medium performs the work.
The energy cost of such a solution is unproductive heating and compression of a part of the working medium returning to the working space (P) (in the above example 100 - 86.7 = 13.3%), although the medium in the gaseous phase remaining in the working space (P) can also be partially used, e.g. to perform work.
For device 15 according to the invention and the parameters according to fig. 1:
The work performed by the steam (86.7% of which is effectively supplied to the cycle): $W_{TA} = h_{3 A} - h_{4A} = (683.74 - 614.99) * 86.7 %=59 .6 kJ / kg$
The work of device 15 according to the invention: W_UA = 0, therefore BWR for the cycle according to fig. 1 with the device according to the invention: BWR_UA =0%
Of course, the actual work needed to drive device 15 according to the invention will, due to the need to overcome the resistance to movement, be greater than 0, and the actual BWR index should take into account the efficiency of the pump drive elements, device 15 according to the invention and the working device. The working device in the compared systems (with the pump or with the device according to the invention) is identical, therefore the ratio of the actual BWR indexes for the system with the device according to the invention (BWR_UAR) and with the pump (BWR_PAR) will be: ${BWR}_{UAR} / {BWR}_{PAR} = ((W_{UA} * q_{UA} / η_{UA} / η_{NUA}) / P_{TA}) / ((W_{PA} * q_{PA} / η_{PA} / η_{NPA}) / P_{TA}) = (\begin{array}{l} W_{UA} * q_{UA} / \\ η_{UA} / η_{NUA} \end{array}) / (W_{PA} * q_{PA} / η_{PA} / η_{NPA})$
where: BWR_UAR - actual BWR for the system with device 15 according to the invention, BWR_PAR - actual BWR for the system with the pump, q_UA - mass flow rates at the outlet of device 15 according to the invention, q_PA - mass flow rates at the pump outlet, η_UA - total efficiency of device 15 according to the invention, η_NUA - total drive efficiency of device 15 according to the invention with a speed controller (VFD), η_PA - total efficiency of the pump, η_NPA - total efficiency of the speed-controlled pump drive (VFD)
P_TA - power on the shaft of the working device
As previously mentioned, the efficiencies of systems consisting of a speed-controlled drive and a pump are, especially for small ORC systems, very low.
If the ORC shown above has a gear pump delivering 5kW output, its mechanical efficiency will be approx. 90% and its volumetric efficiency will be approx. 90%, the efficiency of the electric motor in this power range is approx. 84%, and the efficiency of the speed controller (VFD)) for such a drive power when operating in the range of 50-100% of revolutions is approx. 95%, so the power consumption will be 5/0.9/0.9/0.84/0.95 = 7.7 kW.
If device 15 according to the invention is operated in a comparable system without a pump, only power is required to drive it to overcome the mechanical resistance. Since the mechanical efficiency of the compared gear pump is 90%, it can be assumed that device 15 will need 10% of the power of this pump, i.e. about 0.5 kW, to overcome the resistance to motion.
However, in order to effectively deliver the same amount of the working medium to the evaporator as in the system with the pump, the mass flow rate of the claimed device according to the invention will have to be (ρ_1A/ (ρ_1A - ρ_3A)= 544.31/(544.31-72, 335)*100% = 115% of the pump mass flow rate. It can therefore be assumed that the necessary power of device 15 according to the invention will be 0.5^∗1.15 = approx. 0.6 kW.
Comparing the device according to the invention to a gear pump:

due to the lack of friction of the tooth tip in the chamber and to the lack of radial forces, the mechanical efficiency of device 15 according to the invention will be higher than that of the pump
the volumetric efficiency of device 15 according to the invention will be higher than that of a gear pump with a similar mass flow rate due to the smaller number of leakage paths.

Assuming, unfavourably, the same efficiencies as for the gear pump, i.e. mechanical efficiency approx. 90%, volumetric efficiency approx. 90% and the efficiency of the electric motor in this power range - approx. 75%, the efficiency of the speed controller (VFD)) for such a drive power when operating in the range of 50-100% of rotation - approx. 92%, the power consumption will be 0.6/0.9/0.75/0.92 = 0.97 kW (mechanical efficiency was taken into account by calculating the power needed to overcome resistance to motion).
BWR_UA/BWR_PA= 0.97/7.7 = 12.6%, i.e. the BWR of the device according to the invention will be 7.9 times lower than for the cycle with a pump.
On one hand, one should remember the greater amount of heat needed to obtain a similar output power of the working device, and on the other hand, that the energy of the working medium in the gaseous phase, which remains after exchange in the working space P, can be partially used.
For the same working medium (R600A), the characteristic points of an exemplary supercritical Rankine cycle, shown in fig 2, are as follows (calculations of the working medium parameters at the various points of the thermodynamic cycle were carried out using eThermo Thermodynamics & Transport Properties Calculation (freestd.us@hotmail.com)

in the case of a system with a pump according to the state-of-the-art:
- 1B - upstream of the pump
  - P_1B=0.40472 MPa, T_1B=30°C, s_1B=1.2458 kJ/kgK, h_1B=271.24 kJ/kg,
  - ρ_1B=544.31 kg/m³
- 2B - upstream of the evaporator
  - P_2B=3.7 MPa, T_2B= 31.73 °C, s_2B=1.2458 kJ/kgK, h_2B=277.28 kJ/kg,
  - ρ_2B=542.09 kg/m³
- 3B - upstream of the working device
  - P_3B=3.7 MPa, T_3B=138.68°C, s_3B=2.3785 kJ/kgK, h_3B=696.77 kJ/kg,
  - ρ_3B=141.125 kg/m³
- 4B - upstream of the condenser
  - P_4B=0.40472 MPa, T_4B= 41.05 °C, s_4B=2.3785 kJ / kgK, h_4B= 614.99 kJ/kg,
  - ρ_4B=9.9586 kg/m³,

where: P - pressure, T - temperature, s - entropy, h - enthalpy, ρ - density of the working medium
Work performed by steam: W_TB=h_3B-h_4B=696.77-614.99=81.78 kJ/kg
Work of the pump: W_PB=h_2B-h_1B=277.28-271.24=6.04 kJ/kg
Heat delivered: Q_3B-h_2B=696.77 - 277.28=419.49 kJ/kg
BWR for the cycle according to fig. 2 with a pump: BWR_PB=W_PB/W_TB=6.04/81.78=7.4%

For device 15 according to the invention and the parameters according to fig. 2:
Work of the pump: W_PB = 0, therefore BWR for the cycle according to fig. 2 with the device according to the invention: BUR_UB = 0%
After considering the efficiency, with similar assumptions as for the subcritical cycle, the power consumption of the system with the pump will also be 7.7 kW.
The working medium has a density of 544.31 kg/m³ at point 1B and 141.125 kg/m³ at point 3B, i.e. we effectively deliver (544.31 - 141.125) / 544.31 * 100 = 74.1% of the working medium in the liquid phase from the working space P and this part of the supplied medium performs the work.
In order to effectively deliver the same amount of the working medium to the evaporator as in the system with the pump, the mass flow rate of the claimed device according to the invention will have to be (1/0.741 = 135% of pump mass flow rate).
The power consumption of device 15 according to the invention will be $0.5 kW * 1.35 / 0.9 / 0.75 / 0.92 = 1.1 kW .$
With the same assumptions as for the subcritical cycle, the ratio of the actual BWR indexes for the system with the device according to the invention (BWR_UBR) and with a pump (BWR_PBR) will be: BWR_UBR/BWR_PBR= 1.1/7.7 = 14.2%, i.e., the BWR of the device according to the invention will be 7 times lower than for the cycle with a pump.
Fig. 3, fig. 4, fig. 5 and fig. 6 show the construction of device 15 according to the invention, and in these figures, in an exploded view, without respecting geometrical proportions, the components of device 15 according to the invention are shown in different versions.
Device 15 according to the invention comprises a housing consisting of an upper part 11 of the housing and a lower part 12 of the housing. Both parts 11, 12 of the housing are connected by bolts 14 and are sealed by a seal 8. In housing 11, 12 there is a drum 5 with shafts and a working space P or working spaces P. Fig. 3 shows a drum 5 with one working space P, fig. 4, fig. 5 and fig. 6 with four working spaces P. Drum 5 is driven by a drive 19. Floating plates 6 are arranged on both sides of drum 5 and secured against rotation in respect to housing 11, 12, for example using pin 10. Gaskets 7 are arranged in seats 6A of the floating plates 6 to ensure leak tightness of the different flow paths (respectively at the stages CG, GC and optionally RP and NP) of the working medium and allow to balance the forces acting on both sides on the floating plates 6, thanks to the appropriately selected shape (hence the name "floating plates"), and between floating plates 6 and parts 11, 12 of the housing there are bearings 9. The shaft is sealed by seal 13 arranged at lower part 12 of the housing. The lower part 12 of the housing is provided with drainage F for liquid leaks, and the upper part 11 of the housing is provided with drain E for gaseous leaks.
Device 15 shown in fig. 3 with one working space P in drum 5 is designed to work with two stages of the cycle as shown in the system shown in fig. 7 and fig. 8. This cycle includes stages:

CG- exchanging the working medium in the liquid phase in the working space P for the working medium in the gaseous phase or supercritical state
GC- exchanging the working medium in the gaseous phase or supercritical state in the working space P for the working medium in the liquid phase.

The disadvantage of this solution is the pulsation of pressure when opening the working space P filled with compressed gas at the GC stage. Increasing the number of working spaces P in drum 5 reduces the pulsation, but the pressure upstream of condenser 17 (and downstream of working device 18) will be increased.
Fig. 4 shows device 15, which also implements a two-stage cycle, but has four working spaces P in drum 5. Of course, the number of working spaces can be practically any (the larger, the smaller pressure pulsations are in the system).
In turn, fig. 5 shows device 15 with four working spaces in drum 5, which is designed to work with three stages of the cycle, as shown in the arrangement in fig. 9 and fig. 11. This cycle includes the stages:

CG- exchanging the working medium in the liquid phase in the working space P for the working medium in the gaseous phase or supercritical state
RP - expansion of the working medium in the gaseous phase or supercritical state that is contained in the working space P
GC- exchanging the working medium in the gaseous phase in the working space P for the working medium in the liquid phase

Expansion of the working medium in the gaseous phase or supercritical state in expansion tank 22 (fig. 9) or additional condenser 17A (fig. 11) allows reduction of the pulsation and decreasing the pressure of the working medium in the gaseous phase upstream of condenser 17.
Fig. 6, on the other hand, shows device 15 with four working spaces in drum 5, which is intended to work with four stages of the cycle, as shown in the arrangement shown in fig. 10 and fig. 12. This cycle includes the stages:

CG- exchanging the working medium in the liquid phase in the working space P for the working medium in the gaseous phase or supercritical state
NP - driving additional working device 18A with the compressed working medium in the gaseous phase or supercritical state that is contained in the working space P
RP - expansion of the working medium in the gaseous phase that is contained in the working space P
GC- exchanging the working medium in the gaseous phase in the working space P for the working medium in the liquid phase.

Fig. 7 shows, without respecting the geometrical proportions, device 15 according to the invention in a power plant arrangement that is designed to operate with two stages (CG and GC) of the cycle, and fig. 8 shows a schematic diagram of the same arrangement as shown in fig. 7. In this system, the simplest method of transferring the working medium in the liquid phase from the low-pressure area to the high-pressure area in the thermodynamic cycle, in accordance with the invention, is implemented, which is carried out in the following way.
First, working space P, filled with the working medium in the liquid phase, is opened in the high-pressure and temperature area (shown as CG). Thereby, the working medium in the liquid phase is supplied from working space P to the evaporator, and an equal volume of high-pressure and temperature working medium in the gaseous phase or supercritical state is taken from evaporator 16 to working space P. The working medium in the liquid phase is subjected to the same pressure from above and below - it leaves working space P into expansion tank 20 because it has a much higher density than the surrounding high-pressure and temperature working medium in the gaseous phase or supercritical state. Then, in working space P of device 15, the exchange of the working medium is carried out, i.e. the working medium in the liquid phase is replaced in working space P by the working medium in the gaseous phase or supercritical state. The working medium is subjected to the same pressure from above and below, but since the working medium has a much lower density than the surrounding working medium in the liquid phase, it flows to its surface in expansion tank 21 and flows further to condenser 17, while the working medium in the liquid phase fills space P (which was shown as GC). The working medium in the liquid phase supplied to evaporator 16 (according to the presented example of the subcritical cycle - 86.7% of the working medium in the liquid phase contained in working space P) after evaporation supplies working device 18. Then, the working medium in the low-pressure gaseous phase, after leaving the working device 18, is directed to condenser 17.
In device 15 according to the invention, the working medium in the liquid phase is supplied to the high-pressure area using minimum mechanical work needed only to overcome the resistance to rotation of drum 5.
Fig. 9 shows a schematic diagram of the system, wherein the method with additional expansion stage RP in expansion tank 22 is implemented, i.e. the method comprising stages CG, RP, and GC. In this method, the compressed working medium in the gaseous phase or supercritical state, before being replaced in the working space by the working medium in the liquid phase, is expanded in the expansion tank at expansion stage RP, while the volume of the working medium in the gaseous phase, that after expansion exceeds working volume P, is directed to condenser 17.
Fig. 10 is a schematic diagram of the system where, before expansion stage RP in expansion tank 22, the method with additional stage NP of driving additional working device 18A (stages CG, NP, RP, and GC) is performed. This additional working device 18A is driven by the expansion of the working medium. The pressure upstream of additional working device 18A is lower than pressure P_3A or P_3B upstream of working device 18, and the amount of working medium in the gaseous phase passing through working device 18A is the difference between the amount of working medium in the gaseous phase in working space P at these two pressures. Working device 18A generates much less power than the main working device 18 and is therefore more likely to be used in ORC cycles of larger scale. The possibility of driving device 15 itself using additional working device 18A would require that this device be able to achieve the appropriate rotational speed, and the control should take into account the instability of such a system.
Fig. 11 shows a schematic diagram of the system, wherein the method with additional expansion stage RP is implemented in separate condenser 17A, i.e. a method comprising stages CG, RP, and GC. In this method, the compressed working medium in the gaseous phase or supercritical state is expanded in additional condenser 17A at RP expansion stage before it is replaced in the working space by the working medium in the liquid phase.
Fig. 12 is a schematic diagram of a system where the method with additional stage NP of driving additional working device 18A (stages CG, NP, RP, and GC) is performed before expansion stage RP in additional condenser 17A. This additional working device 18A is driven by the expansion of the working medium. The pressure upstream of additional working device 18A is lower than the pressure P_3A or P_3B upstream of working device 18, and the amount of working medium in the gaseous phase passing through working device 18A is the difference between the amount of working medium in the gaseous phase in working space P at these two pressures. Working device 18A generates much less power than the main working device 18 and is therefore more likely to be used in ORC cycles of larger scale.
If we take a gear pump as the reference device, then:

the mechanical efficiency of device 15, as previously mentioned, should be higher than that of the gear pump due to the lack of friction of the tooth tip in the working space and the lack of radial forces
the volumetric efficiency of device 15 according to the invention, as previously mentioned, should be higher than that of a gear pump with a similar mass flow rate due to the smaller number of leakage paths
no bearings are needed to support heavy radial loads

Claims

A method of transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area, in which a working medium is in the gaseous phase or supercritical state, is characterized in that at least one working space (P) is moved and as a result of the moving the at least one working space (P) is opened at the CG stage in the high-pressure area and the working medium in the liquid phase, having a much higher density than the surrounding working medium in the gaseous phase or supercritical state, is caused to drop from this at least one working space (P), whereby the working medium in the liquid phase is replaced in the working space (P) by the working medium in the gaseous phase or supercritical state.
The method according to claim 1, characterized in that the at least one working space (P) filled after the CG stage with a high-pressure gas is moved and as a result of the moving the at least one working space (P) is opened at the GC stage in a low-pressure area, in which the working medium is in the liquid phase and it is caused to raise the working medium in the gaseous phase or supercritical state, having a significantly lower density than the surrounding working medium in the liquid phase, from the working space (P), and to fill the working space (P) by the working medium in the liquid phase, whereby the working medium in the gaseous phase or supercritical state is replaced in the working space (P) by the working medium in the liquid phase.
The method according to claim 2, characterized in that the compressed working medium in the gaseous phase or supercritical state, before being replaced at the GC stage in the working space by the working medium in the liquid phase, is expanded in expansion tank (22) at expansion stage RP, while the volume of the working medium in the gaseous phase or supercritical state, that after expansion exceeds working volume (P), is directed to condenser (17).
The method according to claim 2, characterized in that the compressed working medium in the gaseous phase or supercritical state, before being replaced at the GC stage in the working space by the working medium in the liquid phase, expands at expansion stage RP, while the volume of the working medium in the gaseous phase or supercritical state, that after expansion exceeds working volume (P), is directed to additional condenser (17A) through a separate path from the working medium in the gaseous phase or supercritical state from the working device (18).
A method according to claims 3 or 4, characterized in that, before the expansion of the compressed working medium in the gaseous phase or supercritical state at RP stage, the working medium is partially expanded at driving stage NP and additional working device (18A) is driven by this working medium.
The method according to claims 1 or 2 or 3 or 4 or 5, characterized in that working space (P) together with the working medium contained therein is moved between different stages of the cycle.
The method according to claim 6, characterized in that the working space together with the working medium contained therein is moved by rotating drum (5) in which at least one working space (P) is arranged.
The method according to claim 7, characterized in that at least one working space (P) in the form of an opening connecting the surfaces of drum (5) in contact with floating plates (6) is moved by rotating drum (5) using drive (19).
A device (15) for transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area, characterized in that it comprises at least:
- drum (5), driven by drive (19), rotating and arranged in housing (11, 12), in which there is at least one working space (P),

- bearing shafts (9) connected to drum (5) and arranged in housing (11, 12),

- two floating plates (6) with openings (GC, CG) arranged in housing (11, 12) and connecting working space (P) to:
- the high-pressure area upstream and downstream of the evaporator, where the working medium in the liquid phase is exchanged in the working space for the working medium in the gaseous phase or supercritical state

- the area upstream and downstream of condenser (17), where the working medium in the gaseous phase or supercritical state is exchanged in working space (P) for the working medium in the liquid phase.
The device according to claim 9, characterized in that the drum is rotatably mounted between floating plates (6) for sealing of rotating working spaces (P).
The device according to claim 9, characterized in that gaskets (7) are arranged in seats (6A) of floating plates (6) for separating the different stages.
The device according to claim 11, characterized in that the gaskets (7) in floating plate seats (6A) are shaped to ensure the balance of the axial forces acting on them.
Device (15) according to claim 9, characterized in that openings (RP) of two floating plates (6) also connect working space (P) to the area where the working medium in the gaseous phase or supercritical state is expanded in working space (P).
Device (15) according to claim 10, characterized in that openings (RP, NP) of two floating plates (6) also connect working space (P) to the area where the working medium in the gaseous phase or supercritical state in working space (P) is expanded and performs work on additional working device (18A).
Device (15) according to claim 9, characterized in that at least one working space (P) is an opening connecting the surfaces of drum (5) in contact with floating plates (6).
A system comprising a device for transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area, an evaporator, a condenser and at least one working device characterized in that device (15) for transferring a working medium in a liquid phase from a low-pressure area to a high-pressure area comprises at least:
- drum (5), driven by drive (19), rotating and arranged in housing (11, 12), in which there is at least one working space (P),

- bearing shafts (9) connected to drum (5) and arranged in housing (11, 12),

- two floating plates (6) with openings (GC, CG) arranged in housing (11, 12) and connecting working space (P) to:
- the high-pressure area upstream and downstream of the evaporator, where the working medium in the liquid phase is exchanged for the working medium in the gaseous phase or supercritical state

- the area upstream and downstream of the condenser (17), where in the working space (P) the working medium in the gaseous phase or supercritical state is exchanged in the working space for the working medium in the liquid phase.
The system according to claim 16, characterized in that openings (RP) of two floating plates (6) also connect working space (P) to the area where the working medium in the gaseous phase or supercritical state is expanded in working space (P).
The system according to claims 16 or 17, characterized in that openings (RP, NP) of two floating plates (6) also connect working space (P) to the area where the working medium in the gaseous phase or supercritical state is expanded in the working space (P) and performs work on additional working device (18A).
The system according to claim 13, characterized in that at least one working space (P) is an opening connecting the surfaces of drum (5) in contact with floating plates (6).