Forced external circulation compression or expansion device with elongate piston free of rotation symmetries, intended for pseudo-isothermal transformations

Abstract

Disclosed is a forced external circulation compression or expansion device intended for pseudo-isothermal transformations. The invention relates to a device that reduces the increases or decreases in temperature of the fluids (3) during these thermodynamic transformations. It consists of a fluid-tight cylinder (1), a mobile piston (2), of elongate shape free of rotational symmetries, performing the compression or expansion, a gaseous or supercritical fluid (3) undergoing this transformation, and two orifices, namely one (11) for discharging and one (10) for admitting the fluid (3). Outside the cylinder (1), the device includes a heat exchanger (4), pipes (6) and a fan (5). In the case of liquid piston, a pump or a hydraulic expander (8) ensures the displacement of the hydraulic liquid (9) via a hydraulic orifice (14). The device may include mobile, fluid-impermeable physical partitions (4), and external thermal reserves (7). The device improves the thermodynamic performance of compressors, heat pumps, ORCs, energy storage and liquefaction units.

Description

Compression or expansion device with forced external circulation, with an elongated piston without rotational symmetries, intended for pseudo-isothermal transformations.

[0001] DEFINITION. In the use of the word "piston", it is necessary to understand a mobile physical object, solid or liquid, of any three-dimensional shape, whose displacement in a sealed cylinder adapted to the shape of the piston, causes, by variation of the volume dedicated to a fluid contained in this cylinder, the compression or expansion of this fluid. In the use of the expression "devoid of rotational symmetries" it is necessary to understand a piston, which does not have rotational symmetries other than that of a possible rotation of 180 degrees, with respect to axes perpendicular to the contact surface by which the piston compresses or expands the fluid in the cylinder. In the use of the expression "piston of elongated shape" it is necessary to understand a piston whose ratio of the length of this contact surface relative to the width of the latter is greater than unity, thus giving an elongated shape to the contact surface of this piston.When using the expression "liquid piston" it is necessary to understand that the piston is made up of a liquid volume, using the movements of the liquid by one or more hydraulic pumps or expanders, to achieve via a hydraulic orifice, the variation in volume necessary for the compression or expansion of the fluid in the cylinder.

[0002] With the urgent need to reduce greenhouse gas emissions, the question arises of improving the energy and exergy efficiency of most thermodynamic cycles such as those intended to simply compress or expand a fluid, those intended to produce heat or cold, those intended to produce or absorb work or those intended for the liquefaction of gases. In the case of gas liquefaction, a strategic area of ​​the energy transition concerning, for example, the bodies CO2, CH4, O2, N2, NH3 and H2, there is also the additional problem of the complexity and cost of liquefaction units, almost always forced to use cascades of state changes of several intermediate fluids to achieve the liquefaction of the desired body, and to use, in addition, for each of these intermediate fluids a plurality of compression stages or expansion stages.

[0003] In the field of compression or expansion of gaseous or supercritical fluids, the easiest equipment to construct and seal almost always includes a turbine or a piston with numerous rotational symmetries, relative to an axis perpendicular to the contact surface of this turbine or piston with the fluid to be compressed or expanded. Thus, compressors and expanders with radial turbines, axial turbines, circular pistons, helical screws, and vanes are extremely widespread. Even the various scroll compressors benefit in their rotary speed from the uniformity of rotational symmetries.

[0004] Due to this particularity, the compressions or expansions carried out by these conventional devices follow an adiabatic type thermodynamic transformation, therefore without possible heat exchange, often called pseudo-isentropic. The term "pseudo" here reflects the fact that all devices introduce a certain level of thermodynamic irreversibility compared to an ideal transformation. In addition, any adiabatic compression of the fluid will produce an increase in its temperature, any expansion will produce a lowering of its temperature, faithfully interpretable according to the isentropic curve of the Enthalpy-Pressure diagram of the fluid considered, apart from irreversibilities.

[0005] The present invention relates to a device for compressing or expanding gaseous or supercritical fluids, intended to ensure pseudo-isothermal thermodynamic transformations, among other things for the purposes of simply compressing or expanding a fluid, or producing heat or cold, or absorbing or producing work, or improving certain gas liquefaction cycles.

[0006] In a few rare applications, this related increase in the temperature of the compressed fluid or this related decrease in the temperature of the expanded fluid can represent an operational advantage. However, whenever the objective of a process is to purely increase the pressure of a fluid or to extract heat of a given temperature from it, it can be calculated by modeling that, depending on the composition of the fluid, its initial states of pressure, temperature and mass volume, and depending on the desired compression ratio, the work required for this pseudo-isentropic compression is unfortunately 20% to 50% higher than that required by a pseudo-isothermal, therefore non-adiabatic, compression.

[0007] Similarly, whenever the objective of a process is to produce work or recover cold of a given temperature, it can be calculated by modeling that, depending on the composition of the fluid, its initial states of pressure, temperature and mass volume, and depending on the desired expansion rate, the work that a pseudo-isothermal expansion could produce would be 20% to 50% greater than that produced by a pseudo-isentropic adiabatic expansion.

[0008] For many years, some inventions have been interested in approaching isothermal compression segments, of course by extractions or inputs of heat during the thermodynamic transformation. These devices or processes are often complex and their results nevertheless modest. The most widespread are based on the staging of compressions or expansions, by which an expensive plurality of compressors is used in the case of compressions, or expanders in the case of expansions, benefiting from extraction or input of heat between these stages. Another method is the injection of liquid droplets (of the fluid itself, or of water or oil) during compressions, such as the device described in patent EP2449259B1.Another method exploits the fact that the liquid of a "liquid piston" moistens in its movement a hollow mass with a high heat exchange surface (with walls, lamellae, or high porosity lining) such as the device described in patent US4446698A, which will make it possible to reduce the temperature variation undergone by the fluid to be compressed or expanded.

[0009] In the invention which is the subject of this application, a promising new approach is described, which however requires moving away from the ease of construction and sealing of existing devices, which use a turbine or a piston without elongation and both having numerous rotational symmetries, relative to an axis perpendicular to the contact surface of this turbine or this piston with the fluid to be compressed or expanded.

[0010] The device which is the subject of the invention consists of a sealed cylinder containing an elongated piston without rotational symmetry, with a length to width ratio generally between 1.50 and 15 depending on the desired level of isotherm, and whose cylinder, adapted to the shape of the piston, is provided with two orifices dedicated to the outlet and re-entry of the fluid at the ends of its length. The device includes externally to the cylinder the support of an exchanger for the necessary extractions or inputs of heat as well as that of a variable speed blower. A forced external circulation is thus ensured in a closed loop between these devices. It is estimated that the blower consumes much less work than the work saved or gained thanks to these pseudo-isothermal transformations, relative to the classic adiabatic transformations which are pseudo-isentropic compressions and expansions.

[0011] In return for a reduced ease of construction and sealing, the device could save 20% to 50% of work in the case of compressions, and recover 20% to 50% of additional work in the case of expansions. In addition to applications to pure compressions and pure expansions of industrial fluids or common natural fluids (CO2, CH4, O2, N2, NH3, H2O, H2, etc.) for uses of densification, expansion or for uses of these fluids as refrigerants of thermodynamic cycles, this invention could also greatly facilitate the most complex liquefactions of fluids, by eliminating stages and / or by reducing the number of cascades of multiple refrigerants.Thanks to the progress of pseudo-isothermal compression, it would be possible, for example, to envisage a significant simplification of the processes of direct liquefaction of methane (CH4), a gas with a powerful greenhouse effect, via the simple liquefaction of carbon dioxide, alias R744 (CO2), or the significant simplification of the liquefaction of hydrogen (H2), very expensive in capex and energy at currently 12-15,000kWh per tonne of liquefied H2, via a simple refrigeration cascade with R744 refrigerant liquefying the nitrogen refrigerant, alias R728 (N2), and also ensuring the extraction of heat linked to the necessary conversion of the fraction of ortho H2 into para H2.

[0012] Furthermore, it is also important to understand that there is currently no gas liquefaction unit of modest capacity that is energy efficient. Either the units are of very high capacity (tens or hundreds of thousands of tons per year) and benefit from the expensive conventional sophistications above (cascades and stages), or they are of lower capacity and then completely different liquefaction processes are used, called Brayton cycles or Stirling cycles, both extremely energy-intensive, based on repeated compression-expansion of an auxiliary fluid simply left in the gaseous phase, often nitrogen (N2) or helium (He).It is this situation of exaggerated energy cost which limits the recovery of methane (CH4), a by-product with a powerful greenhouse effect from liquid oil fields, unfortunately vented or sent to the flare; which limits the availability of small oxygen (O2) production units which would be useful for the facilitated recovery of carbon dioxide (CO2) by oxycombustions freed from atmospheric nitrogen (N2), and which also limits small liquid hydrogen (H2) production units in proximity to renewable energy sources. The device which is the subject of the invention could allow small liquefaction units to obtain efficiencies at least equal to those of current large liquefaction units.

[0013] The accompanying drawings illustrate the invention. Fig. 1

[0014] shows, in the particular case of the Enthalpy-Pressure diagram of the CO2 fluid, the difference in enthalpic variations between a conventional isentropic compression, of segment AB followed by cooling of segment BC, and an isothermal compression of segment AC, of ​​the same starting and finishing points, carried out by 11 circulations tolerating a temperature increase of 15 Kelvin, as well as carried out by 32 circulations tolerating a temperature increase of 5 Kelvin. Fig.2

[0015] describes the entire device in the preferred liquid piston mode. The elongated cylinder (1) receives the liquid piston (2). The fluid (3) circulates in the external exchanger (4) using the blower external to the cylinder (5), via the pipes (6), from the outlet port (11) to the inlet port (10). The movement of the liquid piston is ensured by a pump or a hydraulic expander (8) allowing the entry and exit of the hydraulic liquid (9) via the hydraulic port (14). The optional thermal reserves (7) allow the extraction or supply of heat, coupled with storage functions over time. Note that in the absence of these thermal reserves (7), the environment can possibly be used for this extraction or supply of heat. Fig.3

[0016] details a sectional view of the elongated cylinder (1). The latter receives the liquid piston (2). The fluid outlet ports (11) and the fluid inlet ports (10) are clearly visible, as well as the hydraulic port (14). The elongated cylinder (1) must be able to withstand high pressures, so it is here equipped with two flanges (12) allowing the attachment of its cylinder heads to the ends (13), here removable for ease of assembly. Fig.4

[0017] shows a 3-dimensional view of the elongated cylinder (1). The fluid outlet ports (11) are hidden and the fluid inlet ports (10) are clearly visible, as well as the hydraulic port (14). The elongated cylinder (1) must be able to withstand high pressures, so it is here equipped with two flanges (12) allowing the attachment of its cylinder heads to the ends (13), here removable for ease of assembly. Fig.5

[0018] illustrates the mesh of a finite element simulation of the circulation of the fluid (3) and its pressure, temperature or mass volume states at different points internal to the cylinder-piston assembly. Fig.6

[0019] represents on an Enthalpy-Pressure diagram an illustration of a possible thermodynamic operation of the device, in application of innovative liquefaction of industrial gases, in the particular example where the fluid (3) is methane (CH4) escaping from the pressure safety valves of LNG carriers, called Boil-off recovery in English. The horizontal axis of the abscissa indicates the variations in enthalpy of the CH4 body in kJ / kg and the vertical axis of the ordinate indicates the pressure to which this fluid (3) is subjected in bar. Fig.7

[0020] represents on an Enthalpy-Pressure diagram an illustration of a possible thermodynamic operation of the device, in application of innovative liquefaction of industrial gases, in the particular example where the fluid (3) is hydrogen (H2) The horizontal axis of the abscissas indicates the variations of enthalpy of the body H2 in kJ / kg and the vertical axis of the ordinates indicates the pressure to which this fluid (3) is subjected in Mega Pascal (MPa).

[0021] With reference to the 3 drawings, and, the device is constituted by at least one sealed cylinder (1) containing at least one piston (2) and containing at least one fluid (3) in gaseous or supercritical phase undergoing the movements of the piston (2), by at least two orifices dedicated to the outlet (11) and the re-entry (10) of the fluid (3) at the ends of the length of the cylinder (1), and externally to the cylinder (1) by at least one heat exchanger (4) connected to the orifices by conduits (6) incorporating at least one blower (5), characterized in that this piston (2) is a piston devoid of rotational symmetries and that this piston (2) is an elongated piston with a length to width ratio generally between 1.50 and 15.

[0022] With reference to these drawings, the device can be characterized in that the elongated piston (2) is a solid physical object, possibly benefiting from a rounding of the angles in its ends.

[0023] With reference to these drawings, the device can also be characterized in that the piston (2) is a liquid piston, using the movements of a hydraulic liquid (9) by one or more hydraulic pumps or expanders (8) to achieve, via a hydraulic orifice (14), the variation in volume necessary for the compression or expansion of the fluid (3) in the cylinder (1).

[0024] An improvement can be made to the device in piston-liquid mode (2) in that, to limit the risks of dissolution of the fluid (3) in the hydraulic liquid (9), dissolution detrimental to the maintenance of its mass in the device and detrimental to the operation of the pump (8) or the hydraulic expander (8) by the occurrence of cavitation, a mobile physical separation can also be provided between the hydraulic liquid (9) and the fluid to be compressed or expanded (8). This separation can be obtained for example by confining the hydraulic liquid (9) and / or by confining the fluid (3) to be compressed or expanded by means of flexible tank(s), for example in the form of a membrane or bladder, or by the incorporation of a specific separation liquid or a floating solid membrane at the interface between the fluid (3) and the hydraulic liquid (9).A specific adjustment of the pH of the hydraulic fluid (9) can sometimes also address this dissolution problem.

[0025] With reference to these drawings, it is added that the orifices dedicated to the entry (11) and / or the exit (10) of the fluid (3) at the ends of the elongated cylinder (1) can be provided with an additional tube not shown in the drawings, allowing them to be connected in a single zone to the two pipes (6) for external circulation of the fluid (3) towards the heat exchanger (4). This is for the purpose of facilitating the assembly and disassembly of the components of the device as well as for the purpose of designing elongated cylinders with a single removable end cylinder head (13), rather than with double end cylinder heads (13) and double flanges (12).

[0026] With reference to these drawings, the device may include optional thermal reserves (7) allowing the extraction or supply of heat, coupled with storage functions over time.

[0027] The device which is the subject of the invention can be integrated into a unit for liquefying industrial gases (O2, N2, CO2, CH4, NH3, etc.) in order to simplify the latter thanks to this improvement in the energy performance of compressions and / or expansions, by reducing the number of intermediate refrigerant cascades and / or by eliminating the conventional compression and / or expansion stages necessary for conventional processes.

[0028] The device which is the subject of the invention can be integrated into a hydrogen liquefaction unit in order to greatly simplify the latter, which is very expensive in terms of capex and energy at currently 12-15,000 kWh per tonne of liquefied H2, thanks to this improvement in the energy performance of compressions and / or expansions, and by a radical simplification consisting of a single refrigeration cascade with carbon dioxide refrigerant, alias R744 (CO2) liquefying the nitrogen refrigerant, alias R728 (N2), and also ensuring the extraction of heat linked to the necessary conversion of the ortho hydrogen fraction into para hydrogen. Examples

[0029] As explained by the coupled to the, in the pseudo-isothermal operation of compression of a gaseous or supercritical fluid, the rapid circulation of the fluid (3) in the longitudinal axis of the elongated piston (2) and cylinder (1), allows it to undergo, at the level of a molecular sample, only a succession of very short compressions in the cylinder and to benefit concomitantly from a succession of immediate coolings at each outlet towards the exchanger (4) external to the cylinder (1), the fluid (3) being continuously animated by kinetic energy by the blower (5). This sample of molecules of the fluid (3) will penetrate repeatedly into the cylinder (1) - piston (2) assembly, to undergo short compressions between two coolings. This until the moment when the fluid (3) has reached the desired pressure rise.It is this succession of extremely short residence times in the adiabatic compression zone, followed by immediate cooling, which creates this pseudo-isothermal compression segment, unlike conventional compression, whereby the molecules of a fluid will remain in a cylinder for the entire compression according to an adiabatic segment of pseudo-isentropic compression, without any opportunity to cool by releasing heat.

[0030] Conversely, in the pseudo-isothermal operation of expansions of a gaseous or supercritical fluid (3), the rapid circulation of the fluid (3) in the longitudinal axis of the elongated piston (2) and cylinder (1) allows it to undergo, at the level of a molecular sample, only a short expansion before benefiting from immediate reheating to a set temperature in the exchanger (4) external to the cylinder (1), the fluid being continuously animated by kinetic energy by the blower (5). This sample of molecules of the fluid (3) will then re-enter the cylinder (1) – piston (2) assembly, to undergo new short expansions between two reheatings. This until the moment when the fluid (3) has reached the desired pressure reduction.It is this succession of extremely short residence times in the adiabatic expansion zone, followed by immediate reheating, which creates a pseudo-isothermal expansion segment, unlike conventional expansion whereby the molecules of a fluid will remain in a cylinder for the entire expansion according to an adiabatic segment of pseudo-isentropic expansion, without the opportunity to reheat by receiving heat.

[0031] Of course, it is necessary to tolerate a small variation in the temperature of the fluid (3) in the elongated piston (2) - cylinder (1) assembly with respect to the set temperature of the external heat exchanger (4), for example 5, 10 or 15 Kelvin, so that the heat exchange, generally by sensible heat, can be carried out in this exchanger (4).

[0032] In a preferred embodiment of the invention, it is a liquid piston, using the movements of a hydraulic liquid (9) by one or more hydraulic pumps or expanders (8), which achieves the volume variation necessary for compression or expansion, always in an elongated piston (2) - cylinder (1) assembly. The sealing problems possibly expected from non-cylindrical solid pistons are then avoided in this mode.

[0033] For information, a rounding of the angles in its ends should however allow an elongated solid piston to operate without excessive leaks, as demonstrated by a Japanese competition motorcycle Honda NR750 which raced in the years 1979-80 with elongated, non-cylindrical pistons and cylinders, without this motorcycle however seeking to include the other elements which would have allowed pseudo-isothermal compressions.

[0034] Another advantage of the embodiment incorporating a liquid piston (2) is that this mode allows for multiphase adiabatic expansions of the fluid (3) on other essential segments of the cycle (expansions in the supercritical phase then in the gaseous plus liquid phase), which would damage conventional expansion turbines (expanders). In addition to simplicity, an important related advantage is that, by external recovery, or failing that by external dissipation, of the work thus generated via hydraulic continuity, this adiabatic expansion can then be carried out according to a pseudo-isentropic segment, instead of being carried out according to the classic isenthalpic segment called Joule-Thomson expansion.The difference is fundamental in the case of industrial gas liquefactions because conventionally these Joule-Thomson expansions create a significant irreversibility, of course in the form of heat, which has the effect of producing a fluid (3) with a lower liquid fraction at the end of each expansion. By recovering or dissipating outside the cylinder the work of these essential other segments of the cycle (adiabatic expansions) thanks to the continuity of the hydraulics, we would achieve, by simultaneously exploiting the pseudo-isothermal segments which are the main objects of the invention, less complex and more efficient liquefactions.

[0035] In the is described on an Enthalpy-Pressure diagram an illustration of a possible thermodynamic operation of the device, in application of innovative liquefaction of industrial gases, in the particular example where the fluid (3) is methane (CH4) escaping from the pressure safety valves of liquid LNG carriers, called Boil-off recovery in English. The AB segment illustrates a pseudo isentropic compression of cryogenic methane up to a pressure of around ten bars generating a heating up to -50°C, the BC and CD segments correspond to the main innovation of pseudo isothermal compression of this application, the BC segment in gas phase then the CD segment in highly supercritical phase.Heat extraction takes place in the external exchanger (4) for example thanks to a simple countercurrent flow against CO2 at -55°C Segment DE illustrates the secondary claim set out in the preceding paragraph, which only works with the liquid piston variant, and by which an innovative multiphase expansion segment appears (expansion in supercritical phase then in gaseous plus liquid phase). This pseudo-isentropic expansion produces at its end a fluid with a high liquid content, contrary to the usual isenthalpic expansion called Joule-Thomson. Point F corresponds to the collection of liquid CH4 in the lower part of the separator placed at point E. The non-liquefied fraction of the CH4 thus treated, collected in the upper part of the separator placed at point E, of course returns to point A, thus joining other fresh methane escaping from the valves.It is estimated that this process, thanks to the main innovation and the dependent innovation offered by the hydraulic continuity generating the dissipation of the expansion work, would allow to reduce by 40% the energy consumption of the recovery of Boil-offs of LNG carriers. An equivalent process would apply to the recovery of methane emitted by liquid oil fields.

[0036] In the is described on an Enthalpy-Pressure diagram an illustration of a possible thermodynamic operation of the device, in application of innovative liquefaction of industrial gases, in the particular example where the fluid (3) is hydrogen (H2). . The AB segment illustrates an isobaric cooling of the gaseous H2, obtained at the outlet of the electrolyzers at about ten bar (1 MPa) down to a temperature of -190°C, for example thanks to a countercurrent flow against CO2 at -55°C then against nitrogen at -196°C. By this heat extraction also occurs with the help of a catalyst the natural conversion of 75% of the H2 Ortho into H2 Para. The BC segment corresponds to the main innovation of pseudo isothermal compression of this application, mainly in highly supercritical phase. Heat extraction takes place in the external exchanger (4), here using a simple counter-current flow against nitrogen at -196°C.Segment CD corresponds to isobaric cooling in a highly supercritical phase, thanks to the cold generated by the residual gaseous fraction illustrated by segment GB. Segment DE illustrates the secondary claim set out in the preceding paragraph, which only works with the liquid piston variant, and by which an innovative multiphase expansion segment appears (expansion in the supercritical phase then in the gaseous plus liquid phase). This pseudo-isentropic expansion produces at its end a fluid with a high liquid content, unlike the usual isenthalpic expansion known as Joule-Thomson. Point F corresponds to the collection of liquid H2 in the lower part of the separator placed at point E.The non-liquefied fraction of the H2 thus treated, collected in the upper part of the separator placed at point E, of course returns to point B, giving up its cold in a doubly isobaric manner to segment CD through the previously mentioned segment GB, and thus joins other fresh hydrogen produced by the electrolysers. It is estimated that this process would allow, thanks to the main innovation and the dependent innovation offered by the hydraulic continuity generating the dissipation of the expansion work, to halve the energy consumption of current hydrogen liquefactions, estimated at 12-15,000 kWh per tonne of liquefied H2. Industrial applications

[0037] The first industrial applications of the device are to improve the energy and exergy efficiency of thermodynamic transformations for the purpose of simply compressing or expanding a fluid, or producing heat or cold, or absorbing or producing work, such as ORCs.

[0038] A second category of industrial applications is the integration of the device into gas liquefaction units, a strategic area of ​​the energy transition concerning, for example, CO2, CH4, O2, N2, NH3 and H2 bodies, to reduce the complexity and cost of these liquefaction units. Patent documents

[0039] EP2449259B1 “Compressed air energy storage system using two-phase flow to facilitate heat exchange”.

[0040] US4446698A “Isothermizer system” or “System for producing isotherms” in French.

Claims

The device consists of at least one sealed cylinder (1) containing at least one piston (2) and containing at least one fluid (3) in gaseous or supercritical phase undergoing the movements of the piston (2), by at least two orifices dedicated to the outlet (11) and the re-entry (10) of the fluid (3) at the ends of the length of the cylinder (1), and externally to the cylinder (1) by at least one heat exchanger (4) connected to the orifices (10) (11) by conduits (6) incorporating at least one blower (5), characterized in that this piston (2) is a piston devoid of rotational symmetries and that this piston (2) is an elongated piston with a length to width ratio generally between 1.50 and 15. Device according to claim 1 characterized in that the piston (2) is a solid physical object, possibly benefiting from a rounding of the angles at its ends. Device according to claim 1 characterized in that the piston (2) is a liquid piston, using the movements of a hydraulic liquid (9) by one or more hydraulic pumps or expanders (8) to achieve, via a hydraulic orifice (14), the variation in volume necessary for the compression or expansion of the fluid (3) in the cylinder (1). Device according to claim 3, characterized in that one or more mobile physical separations are provided, such as a flexible bladder, flexible membrane, floating solid membrane, specific separation liquid, or a specific adjustment of the pH of the hydraulic liquid (9), to avoid dissolution of the fluid (3) in the hydraulic liquid (9). Device according to claim 3, characterized in that a multi-phase expansion (supercritical, then liquid plus gas) of the fluid (3) is envisaged in a piston-liquid cylinder and in that the continuity of a hydraulic liquid allows the recovery, or failing that the dissipation, of the expansion energy generated, thus creating a pseudo-isentropic segment for this expansion. Device according to any one of the preceding claims, characterized in that the device which is the subject of the invention is integrated into a unit for liquefying industrial gases (O2, N2, CO2, CH4, NH3, etc.) in order to simplify the latter thanks to this improvement in the energy performance of compressions and / or expansions, by reducing the number of intermediate refrigerant cascades and / or by eliminating the conventional compression and / or expansion stages necessary for conventional processes. Device according to any one of the preceding claims, characterized in that the device which is the subject of the invention is integrated into a hydrogen liquefaction unit in order to greatly simplify the latter, which is very expensive in terms of capex and energy at currently 12-15,000 kWh per tonne of liquefied H2, thanks to this improvement in the energy performance of compressions and / or expansions, this via a simple refrigeration cascade with carbon dioxide refrigerant, alias R744 (CO2) liquefying the nitrogen refrigerant alias R728 (N2), and also ensuring the extraction of heat linked to the necessary conversion of the ortho hydrogen fraction into para hydrogen. Device according to any one of the preceding claims, characterized in that the orifices dedicated to the entry (11) and / or the exit (10) of the fluid (3) are provided with an additional tube allowing them to be connected in a single zone to the two pipes (6) for external circulation of the fluid (3) towards the heat exchanger (4). Device according to any one of the preceding claims, characterized in that optional thermal reserves (7) allow the extraction or supply of heat, coupled with storage functions over time. Use of a device according to any one of claims 1 to 9 for carrying out pseudo-isothermal compressions or expansions of a fluid (3) for the purposes of simple compressions or expansions, or of producing heat or cold, or of absorbing or producing work, or of simplifying certain gas liquefaction cycles.

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