WO2016146858A1

WO2016146858A1 - Reversible thermodynamic device for heat transfer

Info

Publication number: WO2016146858A1
Application number: PCT/EP2016/059719
Authority: WO
Inventors: Alain MOUNIE
Original assignee: Eurl S.P.S.
Priority date: 2015-03-13
Filing date: 2016-05-02
Publication date: 2016-09-22
Also published as: FR3033631A1; FR3033632B1; FR3033632A1; WO2016146858A8

Abstract

The invention relates to a high-efficiency, reversible thermodynamic device for heat transfer by means of vapour compression (single- or multi-stage) and phase change. The invention relates to the design and integration of reversible heat exchangers (6) and (7) which can operate alternately as condenser or flooded evaporator. The invention also relates to the design and integration of an intermediate expansion exchanger (5) which also allows the cycle of the system to be reversed. The design of the entire thermodynamic device, incorporating the aforementioned innovations, allows same to operate reversibly while retaining optimum energy efficiency even in the event of significant temperature differences between its sources. The device is particularly suitable for reversible applications with high compression ratio, such as very-low-temperature coolers (useful cold side) and/or high-temperature heat pumps (useful hot side).

Description

Reversible thermodynamic heat transfer device

Technical Field: The present invention relates to a device

thermodynamic heat transfer by vapor compression (mono or multi-stage) and phase change, reversible, high efficiency. Its process makes it possible to work in a reversible manner, while maintaining optimum energy efficiency even under strong temperature differences between its sources. It is particularly suitable for reversible applications with a high compression ratio, such as very low temperature cooler (useful cold side) and / or such as high temperature heat pump (useful heat side). Background and state of the art search technical: Background research by Google patent, by the tools made available online by the INPI, by the websites of manufacturers of heat pumps or reversible coolers, have not found nor pumps to heat reversible, or reversible coolers with a single compression stage, operating with one or more evaporators embedded in the refrigerant can also operate as a condenser. They also failed to find reversible heat pumps, or reversible coolers with multiple stages of compression (flooded evaporation system or even dry evaporative system) using intermediate exchange devices reversible total injection or partial injection. And this, either, with compressors running without drawing oil with the refrigerant or with compressors while driving. They also failed to find devices used as evaporator operating flooded, reversible and can also operate in condenser. Reversible heat pumps found on the market, whether at a compression stage or at multiple stages of compression, operate with reversible heat exchangers

(Evaporator / condenser) but only with so-called "dry expansion" evaporators and not in "flooded" mode. There are also chillers operating with evaporators in flooded mode but they are non-reversible and can also function as a condenser. This research has also failed to find reversible intermediate exchange devices whether they are total injection or partial injection.

Thermodynamic heat transfer systems are more commonly referred to as coolers or heat pumps. It is actually the same machine, only the interesting side for the user differs. Some thermodynamic systems are even reversible, that is to say they are capable of producing a heating or cooling effect on the side that interests the user. Reversible heat pumps have long been used to heat or cool liquids or gases in industrial, residential, or commercial environments.

FIREPLACE OF REM PLACEM ENT (RULE 26) The basic principle of phase-change gas compression heat pumps is to extract the energy from the outside air (or any other cold source, such as water) to return it to ambient air. a house via, for example, the hydraulic heating network. This transfer of energy from the outside air (cold source) to the environment of the house (hot source, that is to say a medium at a temperature higher than that of the cold source which is, in fact, the source of heat, so we should rather speak of heat sinks or hot wells) is made possible by the work of a compressor, which is typically coupled to three other components that are: the condenser, the expander and the direct expansion evaporator. The amplitude of the cooling cycle relating to it in the enthalpy diagram depends essentially on the evaporation and condensation pressures in relation to the temperature of the cold source (evaporation, low pressure side) and the water temperature of the cooling network. heating (condensation, high pressure side). It should be noted that the heat supplied to the dwelling Qc is the sum of the energy extracted from outside air Qf and a part of the energy W supplied to the compressor, the latter depending on its overall efficiency. The performance of the system is defined by the COP (coefficient of performance of the whole system) which is the ratio between the heat supplied to the dwelling and the energy supplied to the compressor. It is expressed in Watt / Watt.

In summer, the cycle of the heat pump is reversed, the transfer of energy that it realizes will do the air of the environment of the house (source cold) towards the outside (hot source, it that is to say, the medium at a temperature higher than that of the cold source): this is called refrigeration or cooling or air conditioning of the home. The cycle is the same, only its meaning has changed. For the rest we will only talk about heating since the cycle is the same. It will also be recalled that for a two-phase mixture (liquid gas), there is a relationship between the pressure and the temperature.

Moreover, the heat exchange in the evaporator and the condenser being irreversibly effected, that is to say by requiring temperature differences, it follows that: the effective temperature of evaporation of fluid refrigerant needs to be

less than the temperature of the medium to be cooled. o the effective condensing temperature of the refrigerant circulating on the condenser side must be greater than the temperature of the cooling fluid (air, water) of the hot source. The difference between these temperatures is called the nip of the exchangers. It is related to the coefficients and surfaces of exchanges of evaporators and condensers. The smaller this difference, the higher the performance of the thermodynamic system.

One of the drawbacks of these systems concerns the reduction of their power and their performance when the temperature of the cold source (outside temperature for example) decreases and / or when the temperature of the hot source (water of a heating circuit for example) increases. The main reasons for these power and performance drops are related to the decrease in: o the density of the gas at the suction side of the compressor on the low pressure side. o latent heat of condensation on the high pressure side. o The isentropic and volumetric efficiency of the compressor when compression rates increase.

Indeed, the external temperature and the evaporation pressure being coupled, the decrease in the outside temperature causes a decrease in the density of the gas sucked by the compressor causing a reduction in the mass flow rate and the power of the system. As the work of the compressor varies only slightly (increase of the unit work but reduction of the mass flow), the COP of the system will decrease.

When the water temperature increases, two phenomena cause the reduction of the COP and the power of the system. On the one hand, the condensing pressure increases with temperature, the work that must provide the compressor is more important for the same flow. On the other hand, the latent heat (width of the saturation curve on the enthalpic diagram) decreases with increasing pressure, the power of the system will also decrease. This last phenomenon nevertheless remains more or less important depending on the level where one is on the saturation curve and the nature of the gas used.

We can add another phenomenon impacting the power and the COP of the system. The increase in the compression ratio leads to an increase in mechanical stress in the compressor causing an increase in irreversibilities, favoring internal leakage and increasing the impact of dead volumes. Concretely, there is a significant deterioration of the isentropic and volumetric efficiency of the compressor when the compression ratio increases beyond 3.5 with consequent increase in the work of the compressor compared to the theoretical work and a reduction of its refrigerant flow.

Another disadvantage of these systems concerns their operating limits essentially related to the temperature of the discharge gases. This temperature must not not exceed 120 to 140 ° C and is in practice limited between 110 to 115 ° C because of the problems it poses on the oils used in compressors (lower viscosity, degradation). The discharge temperature of the compressor depends and increases according to several parameters which are the polytropic coefficient, the compression ratio and the suction temperature. In practice depending on the compression ratio and the refrigerants used, this temperature is 15 to 50 ° C above the condensation temperature. Thus a condensation temperature of 65 ° C will not be possible beyond a certain compression ratio and therefore up to a certain outside temperature (depending on the refrigerant and the compressor). Heat pumps can be grouped into three broad categories based on the emitters in the home: o low-temperature heat pumps used for underfloor heating. Since the emitter has a large exchange surface, the required temperature seldom exceeds 40 ° C and averages around 35 ° C. These heat pumps operate on small differential condensing temperature / evaporation temperature. o the medium-temperature heat pumps used on fan coils and low-temperature radiators with water temperatures in the range of 40 to 55 ° C. These heat pumps operate on average condensation temperature / evaporation temperature differentials. o High temperature heat pumps operating on radiators or for the preparation of domestic hot water with water temperatures of 55 to 80 ° C. These heat pumps operate on high differential condensing temperature / evaporation temperature.

The design of low temperature heat pumps presents no particular difficulty. It is quite different for a heat pump for high temperature. Indeed, as seen above, the increase in the condensation pressure causes a decrease in power, performance, an increase in the compression ratio and the discharge temperature. This limits the possible evaporation temperature. To overcome these difficulties there are various technologies, the most widespread are among others: cascades systems or systems with total or partial injection. Cascading systems schematically use several pumps

series heat exchanger, each stage operating with the same refrigerant or different. These systems can reach temperatures of 80 ° C or above for evaporation temperatures of -20 ° C, depending on the number of stages and refrigerants used. The performance of these cascade systems is much greater than that of single stage systems and even injection systems, especially for high temperature differentials of condensation / evaporation temperature. When this differential becomes less important, these systems maintain their performance but under condition of a sizing between the displacements of well defined compressors. They nevertheless remain less suitable than the "single stage" systems for low differentials for reasons developed below. Another disadvantage of these systems is their high cost; this is the reason why the number of floors remains in practice limited to two.

A conventional two-stage cascade system consists of two heat pumps in series interconnected by an intermediate exchanger or evapo-condenser. In these systems, the heat supplied to the dwelling is the sum of the heat extracted from the cold source and part of the work supplied by each compressor.

The systems with total or partial injection, have only one circuit and a single refrigerant, they are composed of two (or more) stages of compression with an intermediate cooling of the compressed gases at the same time as a sub-cooling of the liquid condensed. The major advantage of these systems is to reduce the discharge temperatures for operations with a high temperature differential of condensation / evaporation temperature and to improve the COP compared to a traditional system. Indeed, the compression ratio of each compression stage being much lower than that of a single stage system, their discharge temperature and in particular that of the compressor of the second stage in contact with the hot source will be lower. In addition, the isentropic efficiency of each of the stages of

compression, again bound to compression ratio, will be higher resulting in higher system yield.

As seen, the performance of two-stage systems remains less interesting than those of single-stage systems for the low differential condensation temperature / evaporation temperature. Two reasons explain this loss of performance: the isentropic efficiency of the compressors and the dimensioning between the two compressors. The isentropic efficiencies are optimal for compression ratios between 2.5 and 3.5, they drop significantly above these values and lower below. When operating with a low differential

condensing temperature / evaporation temperature the compressors work below these rates. It is possible to add another phenomenon imparting the power and the COP of the heat pumps: the frosting of the exchanger operating with the outside air as cold source (or the frosting of the heat exchanger working with the air of the process for the chillers industrial). Frost is condensed steam then crystallized on the evaporator. This water vapor comes from the air circulating on the exchanger serving as evaporator. The greater the gap between the air temperature and the refrigerant (pinch), the faster the ice will form. On an evaporator frost plays the role of thermal insulation; the exchange coefficient of the heat of the exchanger is degraded, the volume of vapor resulting from the boiling of the refrigerant decreases and the evaporation pressure drops. This, until the increase in the temperature difference between the refrigerant and the air compensates for the lowering of the exchange coefficient. As the evaporation pressure decreases, the efficiency of the thermodynamic cycle deteriorates. It is therefore necessary to defrost the evaporator. On reversible systems with a single evaporator and condenser, the defrosting is carried out by cycle inversion as if to switch to

cooling; but here the goal is to bring, thanks to the hot gas, the heat necessary to melt the frost. This type of defrost is very efficient, the time required for deicing is low, the melting of the frost is homogeneous over the entire surface of the exchanger. The electrical consumption induced by this process is also low and has only a small impact on seasonal efficiency. This process requires the use of a dry expansion evaporator to allow cycle reversal on single evaporator and condenser reversible systems. Compared with flooded evaporators, the heat exchange coefficients are less good, so for the same power exchanged, the nip is larger and the evaporation temperature is lower which degrades the efficiency of the thermodynamic cycle. On the other hand, flooded evaporation mode exchange devices can not be defrosted by simple inversion of the thermodynamic cycle. They can be defrosted by hot gas, but the necessary devices are complex and require several evaporators on the same circuit, valves, valves and automation systems: in this case it is not possible to speak of thermodynamic cycle inversion defrosting. A final phenomenon impacting the power and COP of heat pumps and cooling system is the presence of circulating oil with the fluid

refrigerant. The latter, mechanically necessary for certain types of

compressors, night heat exchanges by also degrading the exchange coefficients. In view of the various technologies and their limitations, the present invention aims to provide a reversible thermodynamic heat transfer device with high energy performance combining the advantages of single-stage and two-stage systems, while solving the problems posed by the simultaneous use or not, flooded evaporators, cycle reversal and tank or exchanger

intermediate injection partial or total.

SUMMARY OF THE INVENTION: To facilitate understanding of this disclosure, the heat exchange device (7) will arbitrarily be selected as being on the utility side of a heat pump (eg, the heat exchanger on the dispensing side of the heat exchanger). water heating or cooling of a home). In hot mode (FIG: 1), this device warms the water of the heating circuit of the house and in cold mode (FIG: 2) this same heat exchange device (7) cools the water circuit for refresh the house. The other exchange device (6) of the machine will therefore be located on the side of the free source (eg air outside the home.

This thermodynamic device for heat transfer by vapor compression (mono or multi-stage) and phase change, reversible, high efficiency, according to the invention, comprises a refrigerant circuit made of pipes and on which are inserted inter alia : two compression stages (1) and (2). Between these two stages of compression is inserted a device with medium pressure (abbreviated MP in the enthalpy diagram) with total injection (5) commonly called "flash tank", this device is designed to mix the hot gases from the stage of

compression (1) with the two-phase mixture from the condensation device (7) expanded at medium pressure (MP) via the expansion device (9) in hot mode (FIG: 1) or condensation device (6) via the expansion device (8) in cold mode (FIG: 2). This device is also designed to ensure mixing and heat exchange between the different phases, which will produce saturated gas and liquid undercooled. It also separates the resulting liquid and gaseous phases so that the second compression stage (2) sucks only saturated gases and the expansion devices (9) in hot mode (FIG: 1) or (8) in cold mode (FIG: 2) are fed only in the liquid phase. This "flash tank" device (5), while fulfilling the previously explained functions, according to the invention, makes it possible to work one-way on the gas phase side while being able to work in both directions of circulation on the side of its phase. liquid. The second compression stage discharges at high pressure (abbreviated HP in the enthalpy diagram) into a cycle inversion device (4) for directing hot gases at high pressure (HP) to the heat exchange device (7). ) in hot mode (FIG: 1) or to the heat exchange device (6) in cold mode (FIG: 2). The heat exchange device receiving these hot gases serves as a condenser: the hot gases are desuperheated, condensed, cooled and stored in a buffer volume before being directed to the intermediate pressure mixing device (5) via the device detent (9) in hot mode (FIG: 1) or (8) in cold mode (FIG: 2). During this transformation, the refrigerant gives way heat in the middle circulating in the heat exchanger (the water of the heating circuit of a dwelling in hot mode (FIG: 1) or outside air in cold mode (FIG: 2) for example). A level control device (13) maintains the level of two-phase mixing constant in the intermediate mixing device (5) by acting on the opening degree of the expansion devices (9) in hot mode (FIG: 1) or ( 8) in cold mode (FIG: 2). The subcooled liquid exiting the tank (5) is directed via a line to the expansion device (8) in hot mode (FIG: 1) or (9) in cold mode (FIG: 2). It is relaxed at low pressure (abbreviated LP in the enthalpy diagram) and is admitted in the heat exchange device (6) in hot mode (FIG: 1) or (7) in cold mode (FIG: 2). The two-phase mixture resulting from the expansion is introduced into the heat exchanger where it evaporates thanks to the input of energy from the medium flowing on the evaporator (the water of the cooling circuit of a dwelling in cold (FIG: 2) or outside air in hot mode (FIG: 1) for example). A level control device (11) in hot mode (FIG: 1) or (12) in cold mode (FIG: 2) maintains the constant two-phase mixing level in the evaporator (6) in hot mode (FIG: 1 ) or (7) in cold mode (FIG: 2) by acting on the degree of opening of the expansion device (8) in hot mode (FIG: 1) or (9) in cold mode (FIG: 2). The two-phase mixing level is maintained above the exchange surface to ensure the flooding thereof and to obtain optimum heat exchange performance. The evaporation device also ensures the separation of the gas phase and the liquid phase so that only the saturated vapors resulting from the vaporization are sucked by the first compression stage via the second channel of the cycle reversal valve (4). ). An expansion device (10) allows the reservoir (5) to be bypassed during the cycle reversals in order to accelerate deicing and to secure the compression stage (2) so that it does not draw liquid during of this transient phase or to improve the overall performance of the thermodynamic heat transfer device as if it operated with a single compression stage when the conditions of the sources are favorable. In this case, the thermodynamic heat transfer device operates with the expansion devices (8) and (9) closed and the expansion device (10) controlled by the level control device (11) in heating mode (FIG: 1) or by the level control device (12) in the cooling mode (FIG: 2). The intermediate exchange device (5) no longer receiving a two-phase mixture, the hot gases coming from the compression stage (1) only pass through the reservoir (5) and then are re-aspirated by the compression stage (2). The assembly thus functions as a single compression stage, the temperature of the gases discharged by the compression stage (2) rises, which may be advantageous for increasing the temperature of the medium to be heated or for increasing the efficiency of the a defrost and therefore reduce the time required for it.

The reversibility of the thermodynamic device of reversible heat transfer with high energy performance is obtained thanks to the reversibility of the intermediate device (5) as previously described. It is also ensured through the use of expansion device (8) (9) (10) allowing a controlled expansion in one direction of passage or in the other or allowing free circulation of the refrigerant with a minimum of pressure loss or by preventing the flow of refrigerant in one direction or the other. The heat exchange devices with the media sources, according to the invention, also allow this reversibility through their ability to operate alternately in condenser or evaporator drowned. The device operating as a condenser (FIG: 10), the high-pressure hot vapors enter a first volume located at a high point which makes it possible to reduce the gas velocity by its dimensioning and to distribute the vapors in the various channels of the device. heat exchange, it then function dispatcher. This first volume is provided with a level regulating device which is not active in condenser mode. The vapors circulate in the heat exchange channels. At the beginning of this circulation, they desuperhuffle (their temperature decreases) then they condense (their temperature remains constant as long as vapors and liquid are present), then the liquid is sub-cooled (its temperature decreases) accumulates in a second volume at low point where it is stored. This volume then acts as an accumulator bottle: since the machine can operate at different temperature regimes, the densities of vapor circulating at the various locations of the circuit can vary. In this case, more or less liquid is stored in this part of the circuit. Likewise, this buffer volume is important because the exchangers of the thermodynamic heat transfer device can be of all kinds (tubes and calenders, plates, microchannels or any other technology). Above all they can be of 2 different types on the same machine: in this case, depending on whether the machine will operate in hot or cold mode, the buffer to be stored in the volume acting accumulator bottle, varies mainly depending on the amount of refrigerant which is necessary for the flooded evaporator (according to its technology) to work properly. The heat exchange device, preferably against the current, allows the refrigerant to exchange heat with the medium to be heated, throughout its transformation from vapor to liquid. It can be seen that the direction of circulation of the refrigerant is from top to bottom when the exchange device has the function of a condenser. The liquid then passes into a diffuser (for example a pipe pierced with a multitude of holes) which has no particular function when the heat exchanger is in hot mode to supply the expansion device which follows it on the circuit. The same heat exchange device also operates as an evaporator (FIG: 10): The liquid mixture and low pressure vapor (LP) from the preceding expansion device is conducted in the low point volume of the heat exchanger at the through the dispenser which allows a homogeneous distribution of vapors and liquids in the different channels. The mixture travels through the channels of the exchanger where the liquid evaporates thanks to the heat input of the medium flowing over the heat exchanger. The channels open into the volume at high point, dimensioned and designed to ensure separation of the liquid and gaseous phase and to avoid the entrainment of liquid. This same volume is equipped with a level controller which ensures that the exchanger is well drowned, admitting more or less refrigerant via the expansion device preceding the heat exchange device. The saturated vapors produced are sucked by the compression device via the cycle reversing valve (4)

This heat exchange device according to the invention makes it possible to work with a flooded evaporator of refrigerant, which optimizes the energy efficiency by allowing the compression device to suck up saturated vapors, by increasing the efficiency of the heat exchange between the medium. and the refrigerant (increase of two-phase exchange coefficients over the entire exchange surface) and reduce the average nip (temperature between air and refrigerant in this case). It is also reversible simply and can therefore work in condenser: the hot gases arrive by the high volume and the gravity forces the condensates to accumulate in the low volume. By reversing the direction of circulation of the refrigerant, and by causing the diphasic mixture to arrive from below, gravity participates in the separation of the liquid and gaseous phases, the liquid remaining in the lower part and the vapors escaping in the upper part.

Air-cooled evaporators experience icing when atmospheric conditions permit. This results in a degradation of the exchange coefficients see a malfunction of the machine if the frost is not treated. Working in a drowned evaporator delays the formation of frost and thus increases the seasonal yield. However, a defrost cycle must be started regularly to melt the ice. The fact that this submerged evaporator is reversible, simply reverse the operating cycle of the system and use the heat exchanger as a condenser to melt the frost.

In hot mode (FIG: 1), the cycle reversing device (4) is in position to transfer hot gases (HP) to the exchange device (7) and for the first compression stage (1) sucks vapors from the exchange device (6). The expansion device (9) is controlled by the level holding device (13) while the level holding device (11) controls the expansion device (8). When the machine switches to cold or defrost mode (FIG: 2), the cycle reversing device (4) switches and directs the hot gases (HP) to the exchange device (6) and ensures that the first compression stage (1) sucks vapors from the exchange device (7). The leveling device (13) takes control of the expansion device (8). When the expansion device (10) is used to "short-circuit" the intermediate mixing device (5), the expansion devices (8) and (9) are closed and the expansion device (10) is controlled by the level holding device (11) in hot mode (FIG: 1) or by the level-keeping device (12) in cold mode (FIG 2)

Optionally, a heat exchanger (non-reversible) can be integrated between the discharge of the compression stage (2) and the cycle reversal device (4) to ensure, for example, the heating of domestic hot water whatever the operating mode of the set (cold mode or warm mode).

Another option is to add a heat exchange device fed from the intermediate device (5), flooded by gravity mode or flooded by forced circulation. The vapors produced and the possibly excess liquid return to the intermediate device (5) to be separated therefrom. The vapors produced are re-aspirated by the compression stage (2). This type of device can be used, for example, for cooling motors, electronic cards or other internal or external parts of the machine regardless of the operating mode of the assembly (cold mode or hot mode).

Example of Embodiments: Compression devices can be realized in different ways:

With two separate compression stages in the form of two independent compressors (or multiple compressors in parallel for each compression stage).

With a single compressor having an intermediate suction port (or multiple compressors of this type connected in parallel).

With a single compressor called "compressor compound" where two stages of compression each having a suction and discharge, which are driven by the same engine (or more compressors of this type connected in parallel).

All compressor technologies can be used, for example:

piston, coil, vane, axial or radial turbine compressors or any other technology. Oil-free devices are particularly suitable for preventing the accumulation of oil by distillation in the exchangers. Compressors operating with oil and causing the circulation of oil with the refrigerant can also be used (FIG: 5 in hot mode and FIG: 6 in cold mode). It is sufficient to add to the circuit oil separation devices (14) and / or distillation or decantation (16) (17) as well as reintegration devices to the compression devices of the collected oil (15) . As described above, the thermodynamic device for heat transfer by vapor compression and phase change, reversible, high efficiency is capable of operating with two or more compression stages but also with a single compression stage by means of the expansion device (10) which bypasses the intermediate mixing device (5). It can therefore also be realized with a single compression stage when the application and the lower distance of source temperatures allow it (FIG: 3 in hot mode with compressor without oil, FIG: 4 in cold mode with compressor without oil and FIG: 7 in a hot mode with a compressor producing oil and a separation, distillation or decantation device and

reinstatement of oil; FIG: 8 in cold mode with compressor producing oil and separation, distillation or decantation and reintegration of oil). This thermodynamic device for heat transfer by vapor compression and phase change, reversible, high efficiency can be realized in a single-block manner where all the functions are grouped in one and the same set. It can also be built in multi-block form where the different functions are divided into different subassemblies connected together by pipes and cabling. This mode of construction is better known as the split system. It can also be realized with several reversible exchangers in parallel to be able for example to heat or cool one or more premises and produce hot water.

The intermediate exchange and mixing device (5) of the FIG. 1 and FIG. 2 diagrams is detailed for the example in the FIG. 13 and FIG 14 diagrams. This device ensures mixing and heat exchange between the hot vapors coming from the first compression stage (1) in FIG. 13 and FIG 14, and the diphasic mixture (8) of FIG. 13 and FIG. 9 of FIG. 14 from the expansion of the condensed liquid from high pressure to medium pressure. This device must ensure the heat exchange, the mixing of the different phases but it must also ensure the separation of the vapor and liquid phases that result, so that the pure vapor phase can be re-aspirated by the second compression stage (2) and the undercooled liquid phase may be discharged through a line to supply the expansion device which supplies the next heat exchanger (9) of FIG. 13 and (8) of FIG. the expansion upstream (8) of FIG 13 and (9) of FIG 14, to admit the right amount of refrigerant to maintain the level constant in the exchange device and intermediate mixing (5). Whether the refrigerant flows from (8) to (9) or (9) to (8), the intermediate exchange and mixing device (5) has the same use, so it is reversible. It is realized in this example FIG 13 and FIG 14 in the form of a tank whose upper volume (above the level of liquid refrigerant) has the function of liquid separator: it is dimensioned to reduce the gas velocities and thus to avoid that liquid is entrained by the suction of the compression stage (2) which is connected to it in the upper part. Separating devices, such as iron straw or baffles or any other device, may be added to improve the separation function. In this embodiment, the part lower below the liquid level is separated into three volumes. In the middle volume, under a grid serving as a diffuser, the hot gases of the first compression stage (1) arrive via a pipe. In one of the contiguous tanks, under a grid serving as a diffuser, the two-phase mixture coming from the expansion at the medium pressure of the liquid condensed at the high pressure in (8) for FIG. 13 and in (9) for FIG. ). The two-phase mixture fills this volume, the gas phase is separated at its free surface to be sucked in (2). The liquid falls overflow into the central tank where the hot gases of the first compression stage (1) arrive. The mixture causes evaporation of a portion of the liquid and cooling of the hot gases from the first compression stage. The gas phase is separated at its free surface to be sucked in (2); the remaining liquid accumulates and ends up overflowing into the last tank where it is separated from the last gas bubbles still potentially present, before being evacuated by a pipe to feed the expansion device which feeds the heat exchange device next: (9) of FIG 13 or (8) of FIG 14. A level control device controls the expansion device located upstream (8) of FIG 13 or (9) of FIG 14, to admit the right amount of refrigerant in order to maintain the constant level in this intermediate exchange and mixing device (5). As the refrigerant flows from (8) to (9) or (9) to (8), this intermediate exchange and mixing device (5) as presented in this exemplary embodiment has the same use: is therefore reversible. This type of device is total injection because all the liquid from the condenser at high pressure is relaxed at medium pressure. Although less effective, the device can also be produced according to the principle of partial injection. In the exemplary embodiment of FIGS. 15 and 16, only a part of the liquid coming from the high-pressure condenser is expanded at medium pressure by an expansion device (30). The remainder of the liquid passes through a heat exchange device and is cooled therethrough with the medium-pressure expanded liquid present on the other side of the exchanger in the tank (5). A level control device (28) maintains the liquid level sufficient to drown the surface of the exchanger by admitting the correct amount of refrigerant via the expansion device (30). In this embodiment of a partial injection device, the upper part of the tank operates in the same manner as the total injection device in liquid and gas phase separator, the gas phase being re-aspirated in the upper part by the second stage of compression (2). Similarly, the hot gases from the compression stage (1) are mixed with the liquid submerging the exchanger, and are sub-cooled by the liquid which evaporates.

These devices can be integrated in thermodynamic heat transfer systems by vapor compression (single or multi-stage) and phase change, reversible operating according to the principle of drowned evaporation but also according to the principle of dry expansion evaporation or any other.

The heat exchange devices between the media of the sources and the refrigerant inside the circuit can be made in different ways. Here are some examples :

FIG. 10: This heat exchange device is composed of a "high" volume (23) and a "low" volume (24) interconnected by refrigerant fluid channels used as a heat exchanger (29) with the gaseous medium (air for example) or liquid medium (water or glycol water for example) or even solid (ice for example).

All exchanger technologies can be used to build this exchanger: tube and shell, tube and fins, micro-channels, plate heat exchangers and others.

The novelty of this type of heat exchange device is that it can operate in a reversible manner alternately in an evaporator flooded or condenser without any other action than the change of the direction of flow of the refrigerant. The gravity that the liquid remains in its lower part and the vapors in its upper part, whether used as an evaporator or condenser. When operating as a condenser: the hot vapors and high pressures arrive in the volume "up" (21), upstream in this mode of operation, sized to reduce speeds, minimize losses and thus ensure a good distribution of the flow between the different channels of the heat exchange part (29). The vapors are then desuperheated in the first part of the channels, then condense in the second part. The third part of the channels ensuring the subcooling of the liquid produced. This liquid is then collected in the low volume (24), downstream in this mode of operation, which is used as a liquid buffer tank. The liquid is then discharged through the pipe (22) downstream. The level controller (25) on the top collector is not active. When the same heat exchange device operates as a flooded evaporator, the low pressure two-phase mixture from the regulator enters the "low" volume (27) where it is distributed between the different channels (a diffuser can be used to improve this diffusion in this case it has no particular function when the exchanger is used as a condenser), the mixture floods the channels of the part used in heat exchanger (29), into the volume

"Up" (23), downstream of the heat exchanger, equipped with a level controller (25) which regulates the flow of the regulator precede the assembly on the circuit, in order to maintain the level of refrigerant above the and maintain sufficient space in the top volume (23) sized and designed for use as a liquid separator. The refrigerant evaporates in contact with the walls of the channels of the exchanger (29), liquids and vapors are separated in the high volume (25). The vapors are sucked at the outlet (28) by the first compression stage. The operation is optimum when the two fluids in exchange (the refrigerant and the fluid of the middle of the source) are countercurrent but the co-current operation also works. In this example, the "high" and "low" volumes are made by over-dimensioning the collectors of the different channels of the exchanger. This can be achieved, for example, by over-dimensioning the collectors "up" and "down" on the refrigerant side of a plate heat exchanger. When the configuration does not make it possible to have a compact system where all the aforementioned functionalities can be grouped together, it is then possible, as in the exemplary embodiment (FIG. 11), to separate the volumes "high" and "low" by a pipe. of the heat exchanger part itself. The operation then remains identical to that of FIG. 10. The upstream and downstream volumes of the exchanger can even be made by over-dimensioning the pipes that connect it to the rest of the installation. It is nevertheless necessary to design these pipes so that they have the same use as the volumes that we have described just before. FIG. 12 shows a more complex variant in which the only change in the direction of circulation of the refrigerant is no longer sufficient to ensure reversibility: a pumping device (27) has been added to force the circulation of the liquid during operation in evaporator mode . This improves the heat exchange and may be necessary in case of use of exchangers with high pressure drop. The two-phase refrigerant is admitted to a "low" volume (24), where it is separated from the gas phase which is conducted by a pipe and an open valve (26) to the "high" volume (23), the pumped liquid circulates in the exchanger (29), evaporates in part. Vapors and excess liquids arrive in the top volume (23) where liquid and vapor are separated. The vapors are sucked in the upper part of the volume (28) the liquid returns to the low volume by another pipe also equipped with an open valve (31) in evaporator mode. In condenser mode, the two valves (26) and (31) are closed and the operation is identical to that of FIG 10 or FIG 11; the hot gases enter the "high" volume (21). As the valves (26) and (31) are closed, the hot gases are forced to circulate in the exchanger (29) and the condensates are collected in the low volume (24) before going out (22).

The reversible expansion devices, (8) (9) (10) of FIG. 1 for example, can be realized with two-way flow regulators with complete closure and full opening function or any other technique that enables this result. .

The cycle reversing device (4) is commonly made with a 4-way valve but it can also be realized with a set of automated valves.

The above exemplary embodiments and device examples

Vapor compression heat transfer thermodynamics (single or multi-stage) and reversible, high-efficiency phase change should not be considered exhaustive or limiting of the invention which, on the contrary, encompasses all variants of shape and configuration that are within the reach of the skilled person or the novice.

Example of industrial application: This thermodynamic device for heat transfer by vapor compression (mono or multi-stage) and phase change, reversible, high efficiency is likely to be applied: in space heating whose emitters require a high water temperature, the reversibility is here necessary to ensure the defrosting of the exchanger on the outside air. It can also be applied for domestic or industrial hot water heating. It is also

particularly suitable for industrial processes of cooling at very low temperature such as freezer or fast cooler or reversibility is necessary for defrosting the exchangers of the cooling process. In summary, it is particularly suitable for any process requiring a thermodynamic cycle of heat transfer by vapor compression (mono or multi-stage) and phase change, reversible and energy efficient, operating under strong temperature differences between the sources. In addition, it adapts very well when the difference between the sources decreases, in order to maintain a high energy efficiency.

Claims

claims

1 / Thermodynamic device for heat transfer by single or multistage vapor compression and phase change, with or without oil. Said device comprises:

- A circuit in which circulates refrigerant and interconnecting the various components of the component.

a single-stage compression assembly (1) or a multi-stage compression assembly comprising at least two compression stages (1; 2).

a cycle inversion device (4) allowing the hot / cold or cold / hot inversion of the thermodynamic cycle.

- Thermal exchange devices with the source media (6; 7) one (or some) operating as an evaporator (s) when the other (or others) operates (s) in a condenser.

- Level control devices (11; 12) of liquid refrigerant in these exchange devices (6; 7).

refrigerant flow management devices (8, 9) admitted in the exchangers (6; 7), which are controlled by the liquid refrigerant level control devices (11; 12).

Said thermodynamic device for heat transfer by single or multi-stage vapor compression and phase change, with or without oil is characterized in that it is reversible (can operate in heating or cooling mode) and operates in a controlled mode. evaporated flooded in hot mode or in cold mode. It can thus benefit from the combination of the advantages of the reversibility of the cycle

thermodynamics and evaporation in flooded regime. This characteristic is obtained by integrating the reversible heat exchangers (6) and (7) with the external environments that can work alternately in flooded evaporation or condenser.

2 / thermodynamic heat transfer device according to claim No. 1, comprising at least two compression stages, characterized in that it comprises between all its compression stages or only between some of its compression stages, one or more compression devices. reversible intermediate exchanges partial injection (20) or total (5) operating in heating or cooling mode, capable of ensuring the heat exchange and subcooling of the refrigerant leaving them regardless of the direction of circulation of the liquid refrigerant therethrough.

3 / thermodynamic device for heat transfer by multi-stage vapor compression and phase change, with or without oil, according to claim 2, characterized in that it comprises at least one or more short-circuit devices ( 10) of the intermediate exchange device (s) with two directions of operation (5,20). This to be able to operate without intermediate injection device to adapt the discharge temperature as needed and to optimize the efficiency of the whole of said heat transfer device. This short circuit device (10) of the intermediate exchange device (s) with two directions of operation (5, 20) is also used during the thermodynamic cycle inversion phases, to accelerate these reversal phases (for defrosting for example) and / or to protect the compression stage located downstream thereof, any liquid refrigerant suction.

4 / thermodynamic device for heat transfer by vapor compression and phase change, with or without oil, according to claim 2 or 3, characterized in that it can also operate in hot mode or in cooling mode with cooling devices. thermal exchange with source media (6; 7) working in dry evaporation with thermostatic and / or pressure control, this replacing or adding the exchangers working in flooded evaporation.