RU2811880C2 - Hybrid compressor and boiler for heat supply/output containing such hybrid compressor - Google Patents

Abstract

FIELD: compressors.

SUBSTANCE: hybrid compressor (8) for compressing the working medium, wherein the compressor contains the first cylinder (1) and the second cylinder (2), connected to each other mechanically through a connecting rod-crank system (5) and pneumatically through a connecting circuit (12), possibly with an optional valve (4), a reversible electric machine (6), wherein the first cylinder includes the first piston (81) that separates the first chamber (Ch1) from the second chamber (Ch2), wherein the second cylinder contains the second piston (82) that separates the third chamber (Ch3) from the fourth chamber (Ch4), which can come into thermal contact with the heat source (21), thus creating a cyclic movement in the second cylinder, and, as for the connecting rod-crank system (5), then the first piston and the second piston are connected to the rotor (52) through the corresponding first and second connecting rod and crank mechanisms (91, 92) with a predetermined angular displacement (θd), with the first cylinder equipped with check valves (61, 62), with the power produced in the second cylinder being transmitted to the first cylinder primarily through the connecting circuit rather than through the connecting rod and crank system.

EFFECT: effective performance.

10 cl, 8 dwg

Description

Field of technology to which the invention relates

The invention relates to compressors for a heat pump circuit and, in particular, relates to a hybrid thermodynamic compressor, which can be driven by a thermal compressor and/or a reversible electrical machine. The invention also relates to hybrid boilers containing such a hybrid thermodynamic compressor.

Context and prior art

Known solutions often use an electric motor to drive a compressor, which forms the working element of the heat pump cycle.

There are also solutions based on an internal combustion engine to drive such a compressor.

Thus, thermal equipment designers typically provide solutions that enable the implementation of thermodynamic solutions that include:

1. Electric heat pumps.

2. Thermal heat pumps.

3. Micro-cogeneration boilers.

The applicant has previously proposed using a new type of so-called “thermal” thermodynamic compressor as a working element of the heat pump cycle.

However, a more flexible solution would be preferable depending on the conditions of use of the heat pump circuit and the availability of different forms of energy to drive the compressor. In particular, at some times it is necessary to be able to produce electrical energy using a thermal source as an auxiliary product (in which case one speaks of "cogeneration"), and at other times to use electrical energy without operating the thermal source.

Disclosure of the invention

To solve this problem, a hybrid thermodynamic compressor is proposed for compressing the working medium, wherein the compressor at least contains:

- a volumetric cylinder (also called the “first cylinder”) (1) and a thermal cylinder (also called the “second cylinder”) (2), connected to each other mechanically through a connecting rod-crank system (5) and pneumatically through a connecting circuit (12),

- a reversible electric machine (6) connected to a connecting rod-crank system (5),

wherein the volumetric cylinder contains a cylindrical body with a first piston (81), which separates the first chamber (Ch1) from the second chamber (Ch2),

wherein the thermal cylinder comprises a cylindrical body with a second piston (82) that separates a third chamber (Ch3), called the cold chamber, from a fourth chamber (Ch4), which can come into thermal contact with the heat source (21), becoming the hot chamber and thus creating a cyclic movement in the thermal cylinder, with a connecting circuit connecting the second chamber to the third chamber,

and, as for the connecting rod and crank system (5), the first piston is connected to the rotor (52) through the first connecting rod and crank mechanism (91), and the second piston is connected directly or indirectly to said rotor through the second connecting rod and crank mechanism (92) with a predetermined angular displacement (θd) created by the connecting rod-crank system between the cycle of the first piston and the cycle of the second piston,

wherein the volumetric cylinder is equipped with an inlet channel with a first check valve (61) and an outlet channel with a second check valve (62) for supplying a working fluid with a second pressure (Pout),

in this case, the power produced in the thermal cylinder is transferred to the volumetric cylinder mainly through the connecting circuit, and not through the connecting rod and crank system.

Thanks to these features, the volumetric cylinder allows the pumping of a working medium in the context of a heat pump cycle, wherein said volumetric cylinder is driven by the action of a thermal cylinder connected thereto and/or by an electrical machine.

It should be noted that, as will be shown below, it is possible to use the same working fluid in the thermal cylinder and in the volumetric cylinder, as well as in the primary circuit of the heat pump.

It should also be noted that, as will be shown below, the volumetric cylinder can be a single-acting or double-acting cylinder.

It should be noted that the predetermined angular displacement (θd) characterizes the lag of the volumetric cycle with respect to the thermal cycle, and this predetermined angular displacement can be anything between 50° and 130°. Preferably it can be obtained by a mechanical structure, if necessary, with the possibility of mechanical adjustment.

The term "first check valve" here refers to the inlet valve of the compressor. The term "second check valve" here refers to the compressor discharge valve.

The expression "the power produced in the thermal cylinder is transmitted to the volume cylinder primarily through the coupling circuit rather than through the crank system" means that more than half of the power produced in the thermal cylinder passes through the pneumatic coupling circuit, preferably more than 75% of the power produced in the thermal cylinder passes through a pneumatic connecting circuit.

In various embodiments of the invention related to the system, one and/or other of the following features, considered separately or in combination, can also be used.

According to a preferred feature, the same working medium can be used in the thermal cylinder and in the volumetric cylinder, preferably, but not restrictively, CO2 can be selected as the working medium. Due to this, even if leaks occur at the level of the piston rings of the first piston, the fluid does not mix, since the same fluid is present on both sides of this piston. The same applies to the second piston. Consequently, the sealing requirements between piston and liner are much less critical than in the case of using two different fluids.

According to the distinctive feature, the following are provided:

- electric compression mode, in which the heat source is switched off and the electric machine operates in motor mode,

- thermal compression mode, in which a heat source is activated, which sets a pulse cycle of reciprocating motion in the thermal cylinder, while the movement of the first piston is ensured by the reciprocating movement of the working medium in the connecting circuit, and the electric machine operates in generator mode.

It should be noted that in each of the two modes, the connecting rod and crank system transmits only a minor part of the thermodynamic power, and, in particular, in the thermal compression mode, the connecting rod and crank system transmits only a minor part of the thermodynamic power, while the main part passes through the connecting circuit.

According to an additional feature, it is also possible to provide a mixed mode in which the movement of the first piston in the volumetric cylinder is created due to the thermal cycle in the first chamber and the electric machine operating in motor mode. This allows for overall flexibility in switching between a thermal source and an electrical source, and switching can occur in near real time.

According to a feature, the predetermined phase shift (θd) is from 80° to 120°, preferably about 95°, with the volumetric cycle lagging this predetermined phase shift with respect to the thermal cylinder. This offset allows you to obtain optimal efficiency.

According to a distinctive feature, the stroke (T1) of the first piston (81) may exceed the stroke (T2) of the second piston (82). This allows the thermodynamic power generated in the thermal cylinder to be balanced with the volumetric pumping power applied in the volumetric cylinder and primarily at operating pressures.

According to another configuration, the stroke (T2) of the second piston (82) may exceed the stroke (T1) of the first piston (81).

According to the configuration, the working volume of the thermal cylinder can be from 1 liter to 5 liters. According to the configuration, the working volume of the volumetric cylinder can be from 1 liter to 5 liters.

According to the configuration, the working volume of the thermal cylinder can exceed the working volume of the volumetric cylinder. According to another configuration, the working volume of the volumetric cylinder may exceed the working volume of the thermal cylinder.

According to a distinctive feature, the following mechanical arrangement can be provided: the axis (Y1) of the volume cylinder and the axis (Y2) of the thermal cylinder are located essentially perpendicular to each other, while additional displacement is provided due to the position of the corresponding connecting crankpins of the first connecting rod-crank mechanism (91 ) and the second connecting rod-crank mechanism (92). Thanks to these features and at an angular displacement of about 90°, it is possible to obtain a rotating rotor with corresponding crankpins for each cylinder with close and even identical angular positions.

According to a variant called "single action" positive displacement compressor, a positive displacement cylinder is used with a single action, and only the first chamber (Ch1) is used for suction and discharge, while the second chamber only works in reciprocating mode with the third chamber through the connecting circuit (12 ), while the inlet channel with the first check valve (61) and the outlet channel with the second check valve (62) are connected to the first chamber.

According to a variant called a "double acting" positive displacement compressor, a positive displacement cylinder is used in double action with a connecting circuit (12), which in this case selectively connects the second chamber to the third chamber via a valve (4), and a transition (7) from the first chamber is provided into the second chamber, wherein the first chamber is equipped with an inlet channel with a first check valve (61) for inlet of the working fluid at the first pressure (Pin), while the transition contains a buffer volume (3) with a third check valve (63) between the first chamber (Ch1 ) and a buffer volume and with a fourth check valve (64) between the buffer volume and the second chamber (Ch2), while the outlet channel with the second check valve (62) is connected to the second chamber.

Thanks to this double-acting configuration, the compressor can provide a higher compression ratio if necessary. This configuration also makes it possible to relax the requirements on the piston rings.

According to an additional feature of the two-stage configuration, when the connecting circuit (12) is equipped with such a valve (4), in the electric compression mode, said valve (4) is closed, the heat source is turned off, and the electric machine operates in the motor mode, and in the thermal compression mode, said valve ( 4) is open, the movement of the first piston is ensured by the reciprocating movement of the working medium in the connecting circuit, and the electric machine operates in generator mode.

According to an additional feature of the single-stage configuration, the connecting circuit (12) can also be equipped with such a valve (4) with identical operation in electrical and thermal modes.

According to a distinctive feature, the piston rod of the volumetric cylinder may have a diameter greater than the diameter of the piston rod of the thermal cylinder. Under these conditions, one can observe the effect of increasing pressure associated with a decrease in area.

An object of the present invention is also a thermodynamic boiler for supplying/removing calories to/from a corresponding room, comprising the above-described hybrid thermal compressor, wherein the thermal compressor provides a compression function for a reversible heat pump type circuit comprising at least one common working fluid circuit, a throttle valve and at least one external device.

According to an embodiment, the boiler may be a cogeneration machine producing electricity.

Brief description of drawings

Other aspects, objects and advantages of the invention will become more apparent from the following description of an embodiment of the invention, presented by way of non-limiting example. The invention will be better understood by reference to the accompanying drawings, in which:

Fig. 1 is a diagram of the claimed hybrid thermodynamic compressor in a single-stage pumping version, with the components shown schematically in a plane.

Fig. 2 is a view similar to FIG. 1, in a two-stage positive displacement compressor version.

Fig. 3 - a design variant of a compressor with a thermal cylinder located perpendicular to the volumetric cylinder.

Fig. 4 is an embodiment similar to that shown in FIG. 2, view from the side of the connecting rod-crank system and in the direction of the volumetric cylinder.

Fig. 5 - cycle diagram with pressures and strokes on the ordinate axis for the single-stage version.

Fig. 6 - diagram of the thermodynamic cycle of a thermal cylinder.

Fig. 7 - cycle diagram with pressures and strokes on the ordinate axis for the two-stage version.

Fig. 8 is a general schematic view of a reversible heat pump system.

Description of embodiments

In different figures, identical or similar elements have the same designations. For clarity, some elements are not shown to scale.

General provisions, compressor heat pump

In fig. 8 shows a heat pump system comprising a hybrid thermal compressor 8, which will be described in more detail below. Compressor 8 performs the compression function in a heat pump type circuit, which may be reversible, as shown here, or non-reversible.

Such a heat pump system includes a coolant circulation circuit 85, a first heat exchanger 87, a second heat exchanger 88 and a throttle valve 86, which plays the opposite role in relation to the compressor. In the case of a reversible system, the throttle valve 86 may be dual, with each part operating in one direction and inoperative in the other. The four-way valve 89 allows the direction of fluid circulation to be reversed in the heat exchangers and throttle valve. In the first configuration, the system takes calories from the first heat exchanger 87 and delivers those calories to the second heat exchanger 88, and in the opposite configuration, the system takes calories from the second heat exchanger 88 and delivers those calories to the first heat exchanger 87.

We are interested in particular in the case of a boiler that includes the function of a heat pump with the extraction of calories from an external device and the supply of these calories to the corresponding room or dwelling.

In this case, the proposed system is based on a hybrid thermal compressor 8, which will be described in detail below, with a common working fluid (or "coolant") circuit, a throttling valve and at least one external device. The boiler contains a hybrid thermal compressor 8 for a heat pump type circuit and can supply the corresponding room/dwelling with calories obtained from the burner.

Typically, the compressor is equipped with an inlet passage with a first check valve 61 (referred to in the art as an "inlet valve") and an outlet passage with a second check valve 62 (referred to in the art as a "discharge valve"). With respect to the primary circuit 85, the compressor draws in fluid through the inlet port at a first pressure Pin and discharges fluid at a second pressure Pout through the outlet port.

Compressor - general provisions - volumetric and thermal cylinders

The hybrid thermal compressor 8 contains a volumetric cylinder (also called the “first cylinder”) 1, a thermal cylinder (also called the “second cylinder”) 2 and a reversible electric machine 6 (D/G from: Motor/Generator, both functions being possible).

As will be shown below, the volumetric cylinder 1 and the thermal cylinder 2 are connected to each other mechanically through the connecting rod-crank system 5 and pneumatically through the connecting circuit 12.

As for the volumetric cylinder 1, it contains a first piston 81, which separates the first chamber Ch1 from the second chamber Ch2, which we will return to later. The first piston 81 moves in a cylindrical sleeve 71, which is a body of rotation about the first axis Y1.

The volumetric cylinder 1 forms at least one positive displacement compressor stage for the primary circuit 85 of the heat pump system.

As for the thermal cylinder 2, it contains a cylindrical body with a second piston 82, which separates the third chamber Ch3, called the cold chamber, from the fourth chamber Ch4. The first piston 81 moves in a cylindrical sleeve 72, which is a body of rotation about the second axis Y2.

The third chamber Ch3 can be cooled using a cooling circuit, symbolically shown in the figures under the designation 26.

The fourth chamber Ch4 may come into thermal contact with the heat source 21, becoming a hot chamber and thereby creating cyclic motion in the thermal cylinder.

The third and fourth chambers Ch3, Ch4 are in pneumatic communication through an external circuit with a sleeve in which the second piston 82 moves. In particular, a regenerator 29 is provided, which maintains a temperature gradient between the cold part and the hot part.

The Y2 axis is vertical along with the fourth chamber located above the third chamber Ch3.

A passage is provided on the outside of the cylinder 72 to allow fluid to pass from the third chamber to the fourth chamber and vice versa. In particular, in the upper part of the fourth chamber Ch4 there is an opening 23 for fluid inlet/outlet, then an annular passage 24 in the hot part to the regenerator 29.

The passage is continued under the regenerator by an annular passage 25 in the cold part, which exits through the bottom into the cold chamber. At this point, the passage is also connected to the external inlet-outlet hole 27.

The structure and operation of such a thermal regeneration compressor is described in document WO2014/202885 filed in the name of the applicant, and information from this document will be used in describing the principle and operation of such a thermal regeneration compressor.

The difference from this document is that in this case, in the cold chamber Ch3 there is no separate suction inlet and discharge outlet, but only an outward connection that sequentially produces suction and discharge as the fluid flows back and forth in the connecting circuit 12.

Thanks to the regenerator 29, the temperature difference between the fourth chamber Ch4 and the third chamber Ch3 remains above 500°C. Typically, the fourth chamber is at a temperature of about 600°C, while the third chamber remains at about 50°C due to the cooling system. It is this temperature gradient and its maintenance over time that drives the thermal regenerative compressor.

The hot source 21 is a burner, such as a gas burner. However, it can be noted that a hot spring can burn any other type of fuel except gas. In other configurations, the hot source may be another type of heat source, solar or otherwise, without combustion. Preferably non-fossil fuels are used.

The connecting circuit 12 selectively connects the second chamber Ch2 to the third chamber Ch3. Valve 4, which is optional in some cases as will be shown below, allows the passage of fluid between the second chamber Ch2 and the third chamber Ch3 to be selectively closed or opened. Valve 4 may be electrical or may be manually operated.

It should be noted that the connecting circuit bypasses the working medium between the second and third chambers Ch2, Ch3; in addition, the same fluid enters the fourth chamber Ch2.

Moreover, preferably the same fluid is used in the first chamber Ch1. Thanks to the use of a single fluid, even if leaks occur at the level of the piston rings 78, this does not pose any problem other than a slight decrease in efficiency, both for the thermal cylinder and the volumetric cylinder.

The same fluid is used in the primary circuit 85 of the heat pump system described with reference to FIGS. 8.

In addition to the primary circuit 85, there may be auxiliary circuits (partially shown in dotted line in FIG. 8) connected to each other through heat exchangers, but without any physical exchange of fluid.

The operating medium can be a gas, preferably, but not limited to, CO2 (R744 in the language of heating and cooling specialists). However, the principle of the present invention can be applied to other operating environments.

Connecting rod and crank system and mechanical design

In fig. 1 shows a schematic diagram in the plane of a thermal compressor in the single-stage pumping version. Components are shown flat for ease of understanding. Shown here are two rotors connected in rotation, respectively with axes X1 and X2.

In fig. 3 and 4 show more realistic configurations from the point of view of an industrial solution.

The connecting rod-crank system 5 mechanically connects the volumetric cylinder 1 and the thermal cylinder 2.

In this first example (FIG. 1), the volumetric cylinder is used as a single-acting cylinder. For suction and injection of fluid into the primary circuit 85, only the first chamber Ch1 is used. The second chamber Ch2 operates only in reciprocating mode with the third chamber through connecting circuit 12. Valve 4 may be missing.

The inlet passage with the first check valve 61 and the outlet passage with the second check valve 62 are both connected to the first chamber Ch1.

Compressor - connecting rod and crank system

The connecting rod-crank system 5 contains a rotor 5 mounted for rotation on the compressor crankcase around the X-axis. This rotor 8 forms the crankshaft, but transmits only a slight mechanical force, unlike a classic crankshaft.

This rotor 5 is made in the form of a rotating part with cranks; in particular, the connecting rod journals are located at a distance from the X axis. The first connecting rod journal is fixed to the rotor at a distance T1/2 from the X axis; the leg of the first connecting rod 91 is fixed to this first crankpin. The second crankpin is fixed to the rotor at a distance T2/2 from the X axis; the leg of the second connecting rod 92 is fixed to this second connecting rod journal.

The first connecting rod 91 is connected by its head to the first rod, fixedly connected to the first piston 81. The second connecting rod 92 is connected by its head to the second rod, fixedly connected to the second piston 82.

Thus, T1 is the stroke of the first piston 81. The working volume of the volumetric cylinder is equal to T1 × S1, where S1 is the cross-section of the first liner 71.

T2 is the stroke of the second piston 82. The working volume of the thermal cylinder is equal to T2 × S2, where S2 is the cross-section of the second sleeve 72.

At the bottom dead center of the first piston, the residual volume of the first chamber Ch1 is very small, less than 5% of the displacement volume, preferably less than 2% of the displacement volume.

At the top dead center of the first piston, the residual volume of the second chamber Ch2 may also be small, less than 5% of the displacement volume, preferably less than 2% of the displacement volume.

However, in a particular single-stage configuration, since the second chamber Ch2 is not used for the volumetric compression function, the residual volume of the second chamber Ch2 at the top dead center of the first piston may be larger, for example, 5% to 15% of the displacement volume.

At the bottom dead center of the second piston 82, the residual volume of the third chamber Ch3 is small, less than 4% of the displacement volume, preferably less than 2% of the displacement volume. At the top dead center of the first piston, the residual volume of the fourth chamber Ch4 is also small, less than 4% of the displacement volume, preferably less than 2% of the displacement volume.

The first piston is connected to the rotor through a first crank mechanism 91, as shown in FIG. 1, with the current position θ1 relative to the reference position at bottom dead center, designated θ0.

The second piston is connected (indirectly through a belt, as schematically shown "on the plane" in Figs. 1 and 2) to the rotor through a second crank mechanism 92 with a current position θ2 relative to the reference position at bottom dead center, designated θ0.

In the figures, rotation occurs clockwise for both connecting rod and crank mechanisms. Volumetric cycle 1 lags by a certain angle relative to thermal cylinder 2.

It is noted that there is an angular displacement θd between the cycle of the first piston and the cycle of the second piston.

This angular displacement θd is determined in advance and is structurally ensured by the connecting rod and crank system. The predetermined phase shift θd is typically selected to be between 80° and 120°. The inventors have found that the optimal value is around 95°, with the volumetric cycle lagging by this predetermined phase shift relative to the thermal cylinder. This offset allows you to obtain optimal efficiency.

As shown in FIG. 3 and 4, the second crank mechanism 92 of the second piston 2 is directly connected to the single rotor 52, as is the first crank mechanism 91. The volume cylinder axis Y1 and the thermal cylinder axis Y2 are arranged perpendicular to each other.

With this right angle arrangement, it is possible to obtain a rotating rotor with corresponding crankpins for each cylinder at close and even identical angular positions with a corresponding crankpin offset, which is expressed as θd - 90 (see Fig. 3).

Typically, a real angular displacement of close to 90° is obtained, and therefore the physical displacement of the first and second crankpins remains relatively small, allowing such a part to be machined in a classical manner and at reasonable cost.

Alternatively, instead of a part with classical cranks, two interconnected eccentrics, adjustable in angular position relative to each other, can be used to adjust a predetermined angular displacement θd depending on the application.

Pneumatic circuit - single stage version

In the single stage version shown in FIG. 1, that is, in the simple-action version, only the first chamber Ch1 is used for suction and discharge. The first check valve 61 is located on the inlet port and on the outlet port together with the second check valve 62, both of which are connected to the first chamber.

In the simple action version, the second chamber Ch2 operates only in reciprocating mode with the third chamber Ch3 via connecting circuit 12.

In this configuration, the first chamber Ch1 sucks in the working fluid through the inlet port at the first pressure Pin and discharges the working fluid at the second pressure Pout through the outlet port.

Two stage version

In this configuration (see Figs. 2 and 3), both chambers of the volumetric cylinder are used to increase the pressure from Pin to Pout.

Transition 7 connects the first chamber Ch1 with the second chamber Ch2. The first chamber is equipped with an inlet port with a first check valve 61, as described above, for inlet of the working fluid at the first pressure Pin. The outlet channel with the second check valve 62 is connected in this case to the second chamber Ch2.

The transition 7 contains a buffer volume 3. The transition contains a third check valve 63 for bypassing the fluid from the first chamber Ch1 into the buffer volume 3 and a fourth check valve 64 for bypassing the fluid from the buffer volume 3 into the second chamber Ch2. The outlet channel, together with the check valve 62, is connected to the second chamber.

The buffer volume 3 has sufficient capacity so that the volume supplied and extracted during the rotation cycle of the rotor represents an amount of fluid no more than 10% of the volume present in the buffer volume 3.

Operation and management

The compressor is called “hybrid”; indeed, it can operate in at least the following two operating modes: electrical and thermal.

Electrical mode: This is an electrical compression mode in which the heat source 21 is turned off, the electric machine operates in motor mode, and valve 4 (if present) is closed. In this electrical mode, no power is produced in the thermal cylinder. It is noted that thermal cylinder 2 does not have a special brake; the second piston operates in a simple movement mode.

Thermal and cogeneration mode: we are talking about thermal compression mode, in which valve 4 is open (if present), heat source 21 is activated and produces a pulsating reciprocating cycle in thermal cylinder 2, while the movement of the first piston 81 depends on the reciprocating movement of the working medium in the connecting circuit, and in which the connecting rod-crank system 5 transmits only a minor part of the thermodynamic power, and the electric machine operates in generator mode.

In this configuration, the power produced in the thermal cylinder 2 is transferred to the volume cylinder 1 mainly through the connecting circuit 12, rather than through the connecting rod-crank system 5. Typically, no more than 60% of the power can be transferred to the volume cylinder 1 through the connecting circuit 12 produced in thermal cylinder 2.

In one configuration, the control logic may specify a binary choice of either electrical mode or thermal mode exclusively.

According to another configuration, the control logic may apply a mixed mode with any participation of a thermal source and an electrical source. In this way, the local electrical surplus, supplemented by calories from a thermal source, can be used to drive the compressor.

In fig. Figure 6 shows the thermodynamic operation of a thermal regeneration compressor. Each of the different phases A, B, C, D illustrates movement in the diagram of pressure versus temperature. Each of the different phases A, B, C, D corresponds to a quarter cycle of the second piston, as shown in FIG. 1, 2 and 3.

As described in more detail in the aforementioned document WO2014/202885, the area covered by curve 94 (cycle ABCD) in FIG. 6 represents the thermodynamic work provided by thermal cylinder 2.

In fig. 5 considers the steady state in a single-stage configuration, while the stroke and pressure diagram shows that the pressure P2 in thermal cylinder 2 changes from P2min, when the fluid temperature is at its minimum in thermal cylinder 2, to P2max, when the fluid temperature is at its maximum. Pmax is achieved near the bottom dead center of the piston 82. Pmin is achieved near the top dead center of the piston 82.

In a single-stage configuration, the pressures Pmin and Pmax are not necessarily related to the pressure values Pin and Pout.

In thermal mode, the thermal power and, therefore, the amplitude P2max-P2min, as well as the piston cross-section, are calculated in such a way that the thermal power exceeds or is equal to the pumping power developed in volumetric cylinder 1.

Therefore: W2 > W1, where

W1 denotes the pumping power developed in the volumetric cylinder 1 and W2 denotes the thermodynamic power developed in the thermal cylinder 2. The power generated by the thermal cylinder is proportional to its average pressure (P2max+P2min)/2.

If W6 denotes the driving force of the electric machine 6, then in thermal mode we can write: W1 = W2 + W6, and taking into account W2 > W1 we get negative W6. W6 represents cogeneration capacity.

In electrical mode, W2=0 (source 21 is off and valve 4 is closed), and the electric machine operates in motor mode, hence W1 = W6. The electric machine controller adjusts the command signals to achieve a set speed value, for example, when operating volumetric cylinder 1.

In a single-stage configuration, valve 4 may or may not be present. In electric mode, it is possible to use chambers Ch3 and Ch4 as compensation chambers connected to the second chamber Ch2. Otherwise, it is possible to provide a sufficient residual volume Ch2 at the top dead center of the first piston 81.

In fig. Figure 7 shows the steady-state mode in a two-stage configuration; the stroke and pressure diagram shows that pressure P3 is relatively stable. The pressure P2max essentially corresponds to the pressure Pout. The pressure P2min essentially corresponds to the pressure P3.

Pressure P1 changes from Pin to P3. The pressure P2 changes from P3 to Pout.

In fig. 7 shows the sequential openings of four check valves 61, 62, 63, 64. The opening of each valve is shown in FIG. 7 with a thick horizontal line corresponding to the valve number.

There is a sequential opening of valves 61, then 62, then 63, then 64 with an overlap in time, which may be more or less significant depending on the corresponding calibration of the check valves.

In the upper part of the figure, the respective positions of the pistons 81, 82 show a predetermined angular displacement θd, in this case with a retardation of the volume cylinder by 90°.

In the example shown in FIG. 7, Pin is about 25 bar, P3 is about 50 bar, Pout is about 75 bar.

In the example shown in FIG. 5, Pin is about 25 bar, Pout is about 65 bar.

Other provisions

For pressures in general, generally Pin is between 15 and 40 bar, and generally Pout is between 60 and 90 bar.

Displacement volumes can be selected depending on power requirements. In some typical cases, the working volume of the thermal cylinder can be from 1 liter to 5 liters. Depending on the configuration, the working volume of the volumetric cylinder can range from 1 liter to 5 liters.

In some typical cases, the T1 stroke exceeds T2. In some other typical cases, the cross section S1 is larger than S2.

In some typical cases, the buffer volume 3 can range from 10 liters to 25 liters.

It should be noted that in the two-stage version, the sealing requirements at the level of the piston rings 78 can be relaxed since the average pressures on both sides of the piston 81 are the same.

Claims (20)

1. Hybrid compressor (8) for compressing the working fluid, wherein the compressor at least contains: - the first cylinder (1) and the second cylinder (2), connected to each other mechanically through a connecting rod-crank system (5) and pneumatically through a connecting circuit (12), - a reversible electric machine (6) connected to a connecting rod-crank system (5), wherein the first cylinder contains a cylindrical body with a first piston (81), which separates the first chamber (Ch1) from the second chamber (Ch2), wherein the second cylinder contains a cylindrical body with a second piston (82) which separates a third chamber (Ch3), called the cold chamber, from a fourth chamber (Ch4), which can come into thermal contact with the heat source (21), becoming a hot chamber and thus creating a cyclic movement in the second cylinder, with the connecting circuit (12) connecting the second chamber to the third chamber, and, as for the connecting rod and crank system (5), the first piston is connected to the rotor (52) through the first connecting rod and crank mechanism (91), and the second piston is connected directly or indirectly to said rotor through the second connecting rod and crank mechanism (92) with a predetermined angular displacement (θd) created by the connecting rod-crank system between the cycle of the first piston and the cycle of the second piston, wherein the first cylinder is equipped with an inlet port with a first check valve (61) and an outlet port with a second check valve (62) for supplying a working fluid with a second pressure (Pout), whereby the power produced in the second cylinder is transmitted to the first cylinder primarily through the connecting circuit rather than through the connecting rod and crank system. 2. The hybrid compressor according to claim 1, which uses the same operating fluid in the second cylinder and in the first cylinder, preferably, but not limited to, CO2. 3. Hybrid compressor according to one of paragraphs 1 or 2, which provides: - electric compression mode, in which the heat source is switched off and the electric machine operates in motor mode, - thermal compression mode, in which a heat source is activated, setting a pulse cycle of reciprocating motion in the second cylinder, while the movement of the first piston is ensured by the reciprocating movement of the working medium in the connecting circuit, while the connecting rod-crank system transmits only a minor part of the thermodynamic power , and the electric machine operates in generator mode. 4. The hybrid compressor according to claim 3, which also provides a mixed mode, in which the movement of the first piston in the first cylinder is created due to the thermal cycle in the first chamber and an electric machine operating in engine mode. 5. Hybrid compressor according to one of paragraphs. 1-4, in which a predetermined phase shift (θd) is from 80° to 120°, preferably about 95°, and the cycle of the first piston is delayed by this predetermined phase shift with respect to the second piston. 6. Hybrid compressor according to one of paragraphs. 1-5, in which the axis (Y1) of the first cylinder and the axis (Y2) of the second cylinder are located substantially perpendicular to each other, wherein additional displacement can be provided due to the position of the corresponding connecting crankpins of the first connecting rod-crank mechanism (91) and second connecting rod-crank mechanism (92). 7. Hybrid compressor according to one of paragraphs. 1-6, in which a first single-acting cylinder is used, only the first chamber (Ch1) is used for suction and discharge, while the second chamber operates only in reciprocating mode with the third chamber through the connecting circuit (12), while the inlet a channel with a first check valve (61) and an outlet channel with a second check valve (62) are connected to the first chamber. 8. Hybrid compressor according to one of paragraphs. 1-6, in which a first double-acting cylinder with a connecting circuit (12) is used, which in this case selectively connects the second chamber with the third chamber through a valve (4), while a transition (7) is provided from the first chamber to the second chamber, with In this case, the first chamber is equipped with an inlet channel with a first check valve (61) for the inlet of the working medium at the first pressure (Pin), wherein the transition contains a buffer volume (3) with a third check valve (63) between the first chamber (Ch1) and the buffer volume and with a fourth check valve (64) between the buffer volume and the second chamber (Ch2), wherein the outlet channel with the second check valve (62) is connected to the second chamber. 9. A boiler for supplying/removing heat to/from the corresponding room, containing a hybrid compressor (8) according to one of paragraphs. 1-8, wherein said compressor provides a compression function in a reversible heat pump type circuit comprising at least one common fluid circuit, a throttle valve and at least one external device. 10. The boiler according to claim 9 in combination with claim 3, wherein said boiler is a cogeneration machine that produces electricity.

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