COOLING DEVICE TO INCREASE THERMODYNAMIC PERFORMANCE

Description

[0001] The invention relates to a heat pump, its use, and in particular the improvement of the thermodynamic efficiency of a heat pump.

[0002] Prior art knows of international application WO20009004124, a prior device for producing heat, in a thermodynamic system, by circulating a fluid under pressure through a plurality of tubes in a bulge of a heat pump conduit in which the fluid is in gaseous form, between a heat exchanger and a compressor.

[0003] Since this earlier device produced heat, it remains difficult for prior art to adapt it to the creation of a heat pump usable as a boiler in winter in a home, or a reversible heat pump usable as a boiler in winter and as an air conditioner in summer. Such a pump transfers heat rather than producing it.

[0004] Documents WO2009053726, US2009113900, JP2001317840 and WO2013164439 describe other prior art devices; more specifically, document WO2009053726 describes a heat pump according to the preamble of claim 1.

[0005] The present invention aims to overcome the drawbacks of the prior art.

[0006] The present invention therefore relates to a heat pump according to the attached claim 1. Particular embodiments are defined in the dependent claims. This heat pump comprises a closed circuit containing a refrigerant and a lubricant, the closed circuit comprising a fluid compressor and a fluid return circuit to the compressor, the compressor extending in the closed circuit between a fluid inlet and a fluid outlet, the return circuit extending in the closed circuit, in addition to the compressor, between the fluid outlet and the fluid inlet, the return circuit comprising a condenser, an expansion valve, and an evaporator, said return circuit comprising a first pipe extending between the fluid outlet and the condenser, a second pipe extending between the condenser and the expansion valve, and a third pipe extending between the expansion valve and the evaporator.and a fourth pipe extending between the evaporator and the fluid inlet, said closed circuit comprising a first bulge of a return circuit pipe containing tubing, the fluid comprising a mixture of a first Freon R32 (difluoromethane), a second Freon R125 (pentafluoroethane) and a third Freon R134a (1,1,1,2-tetrafluoroethane), and the lubricant comprising a synthetic polyolester oil. According to the invention, the first bulge is disposed on said first pipe and the tubing is arranged vertically.

[0007] In specific embodiments of the invention: The closed circuit includes a second bulge in a return circuit pipe; said second bulge is located on the second pipe; the synthetic polyolester oil is of ISO VG 32 class; the synthetic polyolester oil of ISO VG 32 class has the trade name Emkarate ® < RL32-3 MAF; the refrigerant is R407C; the refrigerant is R407A; the first bulge is located vertically; the first bulge is located vertically and with the fluid flowing upwards; the second bulge is located vertically;

[0008] The invention also relates to: the use of the above heat pump for the purpose of heating an enclosure, in which the evaporator is made in thermal contact with the outside of the enclosure and the condenser is made in thermal contact with the inside of the enclosure to improve the thermodynamic efficiency of the heating operation; the use of the above heat pump for the purpose of cooling an enclosure, in which the evaporator is made in thermal contact with the inside of the enclosure and the condenser is made in thermal contact with the outside of the enclosure to improve the thermodynamic efficiency of the cooling operation.

[0009] In one variant, the refrigerant fluid rises in the first bulge.

[0010] These and other features of the present invention will become more apparent in the following detailed description made with reference to the accompanying drawing, given by way of non-limiting illustration, on which the figure 1 schematically represents a heat pump according to an advantageous embodiment of the present invention.

[0011] For the purposes of this invention, the following designations are used: "Heat pump": a thermodynamic device for transferring heat from a source cooled by the heat pump, by extracting heat from that source (or cold source) in contact with the pump's evaporator, to a source heated by the pump, by transferring heat to that source (or hot source) in contact with the pump's condenser. A heat pump also includes a compressor powered by an external energy source, enabling the heat transfer from the cold source to the hot source, in accordance with the second law of thermodynamics, and includes an expansion valve to reduce the pressure imposed on the fluid by the compressor.The condenser and evaporator, which are the heat exchangers of the pump, are connected by two refrigerant transport lines, forming a closed circuit. One line contains the compressor, and the other line contains the expansion valve. This closed fluid circuit contains refrigerant, which is circulated by the compressor from the evaporator to the condenser, and the other from the condenser to the evaporator. The pump is designed to extract heat from the cold source by evaporating the refrigerant in the evaporator, to transfer this heat from the evaporator to the condenser via the compressor, and finally to release this heat to the hot source by condensing the refrigerant in the condenser."Reversible heat pump": a heat pump operating between a cold source and a hot source in which an additional system of fluid valves allows switching from a heating mode (heating the hot source, in contact with a first heat exchanger, via a cold source, in contact with a second heat exchanger) to a cooling mode (cooling the hot source) by reversing the direction of fluid flow in the circuit, or by reversing the order of the heat exchangers in the circuit while maintaining the same fluid flow direction. A reversible heat pump requires heat transfer, not heat generation. "COP": a coefficient of performance Q / W characterizing the thermodynamic efficiency of a pump as a ratio of energy Q, in the form of heat transferred by the pump from the cold source to the hot source, to energy W, in the form of work, usually electrical, required to operate the pump.A high number characterizes an efficient pump. This number can be greater than one without contradicting the second law of thermodynamics. "Freon": the common trade name for chlorofluorocarbons or CFCs classified by various organizations, including ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.), according to a numbered list in which a Freon is listed by an "abc" number, where a = (number of C) - 1, b = (number of H) + 1, and c = number of F. If a is equal to 0, it is omitted from the formula. Freons will be referenced in the application either by their chemical formula, by the name "Freon" followed by an abc number from the classification, by F followed by an abc number, or by R followed by abc.

[0012] The following will be given particular consideration in the application: Freon 32 or R32 or F32 which is difluoromethane; Freon 125 or R125 or F125 which is pentafluoroethane; Freon 134a or F134a or R134a which is 1,1,1,2-tetrafluoroethane; Freon R407C which is a mixture typically of 23% R32, 25% R125 and 52% R134a (Mass Percentages), R407A (20%, 40%, 40%) and R407F (30%, 30%, 40%). All mixtures of R32, R125, and R134a are designated as the "R407 family of refrigerants," a sub-family of the family comprising all refrigerants. R407A, in particular, contains less R134a than R407C. "Synthetic oils" or "POE oils" are synthetic polyolester oils used for compressor lubrication in heat pumps, particularly those used for heating or cooling homes, that use R32, R125, and R134a in the refrigerant composition of the pump.These oils are perfectly miscible, at the pump's evaporator and condensation temperatures, with R32, R125, and R134a, allowing for the return of oil mixed with these refrigerants in liquid phase from the condenser to the pump's evaporator. The gaseous phases of R32, R125, and R134a are also soluble in these oils, ensuring the return of refrigerant in gaseous phase from the evaporator to the pump's compressor and optimizing oil transport, particularly as a mist of oil laden with refrigerant, between the compressor and the pump's heat exchangers—that is, the assembly consisting of the pump's evaporator and condenser. "Vertically arranged": in a heat pump in normal operation, designates for a bulge of a pipe or a pipe tube, an orientation defining a flow direction parallel or antiparallel to the Earth's gravitational field.This concept also refers to a pipe or tube in which the laws of two-phase flow in vertical tubes apply preferentially to the laws of horizontal two-phase flow, due to its orientation. More generally, this concept also refers to a pipe or tube exhibiting a slope for flow and which is therefore not horizontal. The concept is thus not limited, within the meaning of the invention, to strict parallelism to the gravitational field of a tube or a bulge in a pipe.

[0013] The closed circuit includes the fluid compressor 1 and a fluid return circuit to the compressor. The compressor extends within the closed circuit between the fluid inlet and the fluid outlet, while the return circuit extends, parallel to the compressor, between the fluid outlet and the fluid inlet. The return circuit includes the condenser 2, the expansion valve 3, and the evaporator 4. This return circuit thus comprises a first line extending from the fluid outlet to the condenser, a second line extending from the condenser to the expansion valve, a third line extending from the expansion valve to the evaporator, and a fourth line extending from the evaporator to the fluid inlet.

[0014] According to the invention, said closed circuit comprises a first bulge 5 of a return circuit conduit containing tubing 50, the fluid comprising a mixture of a first freon R32 (difluoromethane), a second freon R125 (pentafluoroethane) and a third freon R134a (1,1,1,2-tetrafluoroethane), and the lubricant comprises a synthetic polyolester oil.

[0015] The invention is described below by way of example with reference to a figure 1 This represents a heat pump equipped with two pipe bulges: a first pipe bulge 5, with tubing 50, located between a fluid outlet of the pump's compressor 1 and a condenser 2 of the pump, and a second bulge 6 without tubing located between the condenser 2 and the expansion valve 3 of the pump. The pump also has an evaporator 4. However, a single bulge is also possible.

[0016] For example, an AIRWELL ® brand heat pump with a nominal power of 12kW can be used for heating.

[0017] The invention can also be implemented with a reference AIRMEC® heat pump, model ANF 50 with a power output of 15kW or ANF 100 with a power output of 35kW. Therefore, the invention is not limited to a particular manufacturer or model.

[0018] The pump can use a set of copper pipes with an inner diameter of fourteen millimeters (14 mm) forming a closed circuit that is sealed against gases and liquids, the closed circuit being immersed in the atmosphere.

[0019] A ZB38KCE reference compressor 1, having a fluid inlet and a fluid outlet, is inserted into this circuit. Following the closed circuit outside the compressor, from the fluid outlet or discharge of the compressor to the fluid inlet or suction of the compressor, one encounters in series within the closed circuit a first bulge 5 with tubes 50, a condenser 2, a second bulge 6 without tubes, an expansion valve 3, and an evaporator 4.

[0020] The first tube bulge is formed, on a first 14 mm pipe, by a local increase in the pipe's internal diameter, or first bulge. This first bulge 5 contains internal tubes 50, for example, seven tubes with an internal diameter of 5 mm and an external diameter of 8.5 mm, surrounded by the first bulge of the pipe. The internal diameter of the bulge is adapted to accommodate the tubes, and the thickness of the bulge is adapted to withstand the maximum pressure specified for the fluid in this part of the pump.

[0021] The inner diameter of the bulge, for 7 tubes packed tightly together, is equal to 3 times the outer diameter of one tube, or approximately 25.5 mm. For a larger number of tubes, this inner diameter of the bulge can be deduced as the outer diameter of the tubes, packed tightly together.

[0022] We will choose a sum of the internal sections of the 5mm tubes equal to the internal section of the 14mm pipe for a 15kW pump and equal to twice the internal section for a 35kW pump.

[0023] In the case where a pipe with a larger internal cross-section is to be fitted with a bulge, the same ratio between the diameter of the tubing and the diameter of the pipe will be chosen as in this first embodiment, i.e. here a ratio equal to 14mm / 5mm or 2.8.

[0024] The length of the tubing of the first bulge will be taken to be approximately 22 cm for an original AERMEC ®< pump and 13 cm for an original AIRWELL ®< pump.

[0025] The condenser, a known component, is encountered in the circuit following the first bulge.

[0026] The second bulge is designed to operate in the liquid phase for the refrigerant and oil. It is, for example, identical to the first bulge, but may or may not include tubing, as this has not been deemed essential for achieving the effect of the invention with the second bulge present in the circuit in addition to the first. The second bulge is followed downstream by the expansion valve. The expansion valve is a known component, operating primarily in the liquid phase at its inlet, and designed to produce a two-phase mixture of gas and liquid during the normal operation of the heat pump of the invention.

[0027] The expansion valve is followed downstream of the evaporator, a known component.

[0028] In use in heating mode, the pump is in contact at the evaporator with the atmosphere surrounding a space to be heated and at the condenser with a heating circuit of the space.

[0029] In cooling mode use, the pump is in contact at the evaporator with an enclosure to be cooled and at the condenser with the atmosphere surrounding the enclosure.

[0030] Known fluidic valves can allow switching from heating mode to cooling mode via user action, if the pump according to the invention is to be reversible.

[0031] The freon chosen for all pumps is an R407C or R407A freon and the oil is an EMKARATE ®< RL32-3 MAF oil, miscible with the chosen freon at all operating temperatures.

[0032] In general, for the implementation of the invention, a refrigerant and an oil which are miscible with each other will be used.

[0033] The family of refrigerant fluids consisting of R407 freons and oils miscible with freons of this family constitute in particular a set of fluids usable with the invention.

[0034] Regardless of the explanation of the physical phenomenon at the origin of the invention applied to a commercial pump modified by the first tube bulge and the second bulge and operating with a mixture of EMKARATE ®< RL32-3 MAF oil and a mixture of R32, R125 and R134a, certain indications below observed by the applicant during numerous experiments can be used by a person skilled in the art to reproduce, adapt or extend the invention to other mixtures of refrigerants and oil and to design, through its teaching, a heat pump with improved thermodynamic efficiency.

[0035] The general principle of the invention, as of the patent date, is estimated to be the ability to transport oil from a heat pump in the form of an emulsion of oil droplets, which enhances heat exchange in the pump's condenser and evaporator. The means of the invention, namely the first and second bulges, thus aim to regenerate or maintain this emulsion in a form conducive to improving the operation of the pump's heat exchangers (condenser and evaporator).

[0036] The presence of droplets, taken as synonyms for bubbles (containing gas) in a gaseous transport medium or of droplets taken as synonyms for "antibubbles" (oil bubbles containing gas) in a liquid transport medium, is considered to provide nucleation sites for the condensation of the transport medium or for the evaporation of this medium, promoting heat exchange, during its phase changes in the pump exchangers.

[0037] This emulsion is estimated, in the gas phase, to be a mist of droplets forming a "monodispersed" oil emulsion (i.e., droplets whose diameters are highly concentrated around a common value) with a lifespan sufficient to reach the condenser and improve heat exchange there. The invention therefore uses a first method of forming an oil mist between the compressor and the condenser. A particular method is thus a means of imposing a vacuum on oil droplets that have absorbed a transport refrigerant gas due to the solubility of the gas in the oil, and causing the formation of gas bubbles within the droplets, which are then capable of bursting into finer droplets.

[0038] This emulsion is estimated, in liquid phase, to be a mixture of oil droplets forming a "monodispersed" oil emulsion, in a liquid phase, with a lifespan sufficient to reach the expansion valve, pass through it, reach the evaporator and improve heat exchange there, to finally return to the compressor regularly over time in the form of an oil mist with a regular oil droplet diameter and improve its isentropic efficiency by improved lubrication, compared to a commercial pump.

[0039] The invention thus uses, to improve the COP of a heat pump, a first means of forming an oil mist between the compressor and the condenser and a second means of forming a dispersion of oil droplets in liquid phase between the condenser and the compressor, these droplets being able to burst into droplets or bubbles when passing through the expansion valve and reach the evaporator.

[0040] The elements of the invention, namely the first tube-shaped bulge and the second bulge, can thus be adapted by a person skilled in the art to achieve this goal.

[0041] Only the tube-based bulge was previously known in the gaseous phase with any freon and as a secondary heat source.

[0042] The improvement in the thermodynamic efficiency or COP of an entire heat pump using one or two bulges, a specific refrigerant, and an oil miscible with the refrigerant, was therefore not expected in the prior art. The effect obtained makes it possible to consider heating or cooling applications with a pump equipped with at least one bulge.

[0043] This improvement is achieved without an increase in temperature across the terminals of the first bulge used alone, which therefore does not function as a secondary heat source.

[0044] It was thus possible with the invention to observe with R407C with a single tubed bulge, an increase in COP of 27% at +7°C, on an AIRWELL ®< pump.

[0045] With R407A, a COP increase of 21% was achieved at the same temperature.

[0046] Comparable results in percentage gains in COP were obtained for an AERMEC ®< ANF 50 or ANF 100 pump.

[0047] However, with only one bulge, this COP improvement result degrades below +7°C when only one bulge is used. In particular, it becomes practically unusable at 0°C, with the COP gain falling below 10%.

[0048] To obtain a gain in COP over an extended range from -7°C to +7°C, the second bulge is added to the first bulge.

[0049] In this case, for an AIRWELL® brand machine, the observed thermal power increase characteristics were as follows with the two bulges, also called the invention kit: HAS) AIRWELL® machine < 12kW nominal - R407C and POE oil A.1) Temperature 7°C: Manufacturer's power 12.72 kW; power with kit 16.1 kW; COP gain 27% A.2) Temperature 0°C: Manufacturer's power 10.65 kW; power with kit 14.24 kW; COP gain 34% A.3) Temperature -7°C: Manufacturer's power 8.5 kW; power with kit 11.67 kW; COP gain 37% B) AIRWELL® machine < 12kW nominal - R407A and POE oil B.1) Temperature 7°C: Manufacturer's power 12.67 kW; power with kit 15.28 kW; COP gain 21% B.2) Temperature 0°C: Manufacturer's power 11.09 kW; power with kit 13.65 kW; COP gain 23% B.3) Temperature -7°C: Manufacturer's power 9.03 kW; power with kit 10.32 kW; COP gain 14%

[0050] Comparable results in percentage gains in COP were obtained for an AERMEC ®< ANF 50 pump or an ANF 100 pump.

[0051] It can therefore be seen that the two bulges ensure a COP improvement across a wide temperature range, particularly at lower temperatures. It is also noted that in a preferred configuration of the invention, R407C will be used with an oil miscible with it, such as a polyolester or POE oil.

[0052] These results therefore demonstrate the usefulness of the invention in terms of energy saving in the use of a heat pump.

[0053] The elements of this first mode are explained in more detail below.

[0054] The first bulge consists, along its length, of a closed circuit from the compressor fluid outlet to the first pipe joining the compressor fluid outlet to the condenser, of a first zone of increasing internal diameter of the pipe, a second zone of constant internal diameter of the pipe and a third zone of decreasing internal diameter of the pipe.

[0055] As is known, the change in diameter of the first zone can be achieved by a first cone whose apex angle allows, for normal fluidic operating conditions of the pump, to cause a separation of the streamlines of the fluid flowing through the pump.

[0056] As is known, the change in diameter of the third zone can be achieved by a second cone whose angle at the apex allows, for normal fluidic operating conditions of the pump, not to cause a separation of the streamlines of the fluid flowing through the pump.

[0057] In any case, the second zone of the first bulge will advantageously be arranged vertically when the refrigerant is a mixture of Freons and oil. This zone will thus have a chimney-like configuration or function as a chimney or vertical duct for the first bulge, which normally operates with a gaseous refrigerant and oil droplets.

[0058] This arrangement will allow heat transfer to the condenser and not heat production that does not reach the condenser by increasing the lifespan of the Freon emulsion and oil droplets after the fluid has passed through the first bulge and by allowing them to reach the condenser despite coalescence.

[0059] Such a vertical structure allows, for a soluble freon or a mixture of soluble freons in an oil present in droplets transported with the gas, many simultaneous effects resulting in the creation or regeneration of a time-stable emulsion of gas and oil, such as that classically produced by the compressor, at its discharge outlet, and in which the droplets are usually "polydispersed" (i.e. widely variable around a central value) in diameter.

[0060] Examples of these effects include: a Joule-Thomson expansion in the first cone allowing the part of the gases soluble in the oil droplets to form bubbles bursting into droplets smaller than the droplets and well calibrated; a separation of the fluid streamlines causing a dead volume in the first cone at the level of which turbulence is created which divides the droplets which are transported there; a selection of the droplets by the vertical tubes prohibiting or discouraging the circulation of the oil in the form of a film towards the condenser, by causing waves along the tubes and producing foam of droplets along these tubes from an oil film on the walls of the tubes;a selection of droplets by the vertical tubes acting as a collimator of the direction of the droplets and their mass, favoring the transport of droplets rather than the drops themselves, the mass of the droplets favoring their trapping along the tubes and their transformation into a foam of droplets in a manner known in two-phase fluid mechanics in vertical tubes; a calming of the flow by the tubes and the second cone, allowing the transport of droplets created by the first vertical bulge without coalescence and with low pressure losses to the condenser which follows the first bulge in the circuit.

[0061] For a mixture of refrigerant gas and oil, a person skilled in the art can modify the length of the tubes and their diameter to obtain an oil division effect favorable to increasing the thermodynamic efficiency of the pump, efficiency or COP measured by means known in the prior art.

[0062] Specifically, a change in the circulating composition of the mixture initially introduced into the fluid circuit can be an indicator of the invention's operation. For an initial mixture of R407C, variations in the mixture's composition measured at the compressor outlet can be observed over time, depending on operating conditions: ambient temperature, hydraulic circuit temperature, and expansion valve setting. Since the differential solubility of the R407C components in oil is variable, oil trapping in the tubes of the first bulge could also explain this variation in circulating composition.

[0063] However, such a variation, which also changes the density of the circulating mixture, cannot alone explain an increase in COP, as a parallel increase in the electrical power required to move this heavier mixture must be provided. The influence of the mutual solubility of the oil and the refrigerants is therefore considered a useful indicator for fine-tuning the first vertical bulge in the various practical applications of pumps according to the invention operating with R407C or its variants, or with a mixture of R32, R125, and R134a in non-standard proportions.

[0064] It is not excluded that a particular freon other than a mixture of R32, R125 and R134a could also be used according to the invention insofar as an increase in the thermal power of the condenser is observed upon the introduction of a first bulge in the fluidic circuit of a pump operating with this particular freon.

[0065] More generally, as previously stated, a particular mixture of any refrigerant (Freon or otherwise) and an oil soluble with any gaseous refrigerant and miscible with any liquid refrigerant, at the operating temperatures of the closed circuit of a heat pump, a particular mixture which would allow an increase in the thermal power of the condenser to be observed upon the introduction of a first vertical tube bulge between the compressor and the condenser of the heat pump operating with this particular mixture, would be in accordance with the teaching of the invention.

[0066] A skilled technician, faced with such an increase, can adjust the tube lengths or the distance between the first bulge of the condenser and the fluid circuit to optimize the observed power increase in the condenser. This can be achieved, for example, by measuring the temperature of a hot water outlet from a heating circuit in thermal contact with the condenser. They can also vary the verticality of the tubes, allowing for an angle that maintains a downward slope for the oil flow, thus maintaining a similar effect on the condenser's thermal power compared to a strictly vertical orientation.

[0067] For refrigerant and oil pairs according to the invention and using a mixture of R32, R125 and R134a, the COP improvement percentages for R407C, R407A and R407F are as follows: 407C 407A 407F Ambient air COP Gain COP Gain COP Gain 7°C 27% 21% -3% 0°C 34% 23% 12% -7°C 37% 14% 3%

[0068] For a general refrigerant, a mixture of oil in the form of oil droplets and gas, such as Freons in the gaseous phase, passing through the first bulge, this structure is designed to provide a means of regularly dividing the oil droplets, resulting in the formation of a sufficiently stable droplet-gas emulsion, in terms of droplet lifetime, to allow them to reach the condenser and form nucleation sites, thereby improving heat exchange in the condenser and the thermodynamic efficiency of the pump. For a foaming oil-gas mixture, the same general inventive idea of ​​a means of forming an emulsion will be applied to the design of the first tube-shaped bulge, but instead of an emulsion of droplets in one or more gases, the first bulge will be designed to form an emulsion of bubbles in the gas or gases.

[0069] A mixed mode in which an emulsion of oil droplets but also of oil bubbles is formed by the first bulge between the oil and the freons present in the first pipe is not excluded depending on the relative surface tension properties of the oil and the freons at the operating temperature and pressure of the fluid in the first pipe.

[0070] The invention was tested with mixtures of R32, R125 and R134a freons induced by an introduction of R407C and a particular EMKARATE ®< RL32-3 MAF oil into the circuit of a pump modified by the first vertically arranged bulge and having the second bulge.

[0071] Any refrigerant and an oil soluble and miscible with that refrigerant, producing an increase in the condenser's thermal output in the same circuit, would conform to the teachings of the invention, this increase being a criterion of the invention. The result of the invention is, however, obtained when this increase in output is achieved simultaneously with an increase in COP. A person skilled in the art can therefore determine, by introducing the second bulge, which refrigerant-oil combinations cause an increase in thermal output and thus also cause an increase in COP.

[0072] In particular, for Freons, a synthetic polyolester oil or "POE" family comprising oils known to be miscible with Freons in liquid phase and in which Freons in gaseous phase are soluble, would conform to the teaching of the invention with Freons.

[0073] In a second embodiment of the invention, the operation of a commercially available AERMEC ®< ANF 50 heat pump modified according to the invention is detailed in terms of pressure and temperature in the pump.

[0074] A compressor (reference ZB38KCE) is used. This compressor is of so-called "Scroll" technology and it pumps a mixture of EMKARATE ®< RL32-3 MAF polyolester oil, gaseous R32, gaseous R125 and gaseous R134a at a temperature of T = 87°C and a pressure of P = 18 bar.

[0075] The oil is considered to be in liquid form throughout the closed circuit at the temperatures and pressures mentioned.

[0076] The first bulge is vertical, and as the fluid rises, it experiences an inlet pressure of 18 bar and an outlet temperature of 84°C. The mixture of R32, R125, and R134a is gaseous at the outlet. Therefore, under normal operating conditions in this embodiment, there is no temperature increase at the outlet of the first bulge compared to its inlet, and this bulge does not function as a heat source.

[0077] The condenser has an inlet pressure of 18 bar and an outlet temperature of 84°C, and an outlet pressure of 18 bar and 45°C. The mixture of R32, R125, and R134a is liquid at the outlet.

[0078] The second bulge is vertically downward and has an inlet pressure of 18 bar and a temperature of 45 °C, and an outlet pressure of 18 bar and a temperature of 45 °C. The mixture of R32, R125, and R134a is liquid at the outlet, with two-phase liquid-gas periods during which bubbles appear. Therefore, in normal operation of this embodiment, there is no temperature increase at the outlet of the second bulge compared to its inlet, and this bulge does not function as a heat source.

[0079] The pressure regulator reads P = 7 bar, T = 13°C at the outlet. The mixture of R32, R125 and R134a is a two-phase liquid-gas mixture at the outlet.

[0080] The evaporator sees P = 7 bar and T = 13°C at the inlet. The mixture of R32, R125 and R134a is gaseous at the outlet.

[0081] The compressor draws in a mixture of EMKARATE ®< RL32-3 MAF oil, R32, R125 and R134 at P = 4 bars and T = 5°C.

[0082] For this configuration, the COP gains are comparable to those of an AIRWELL ® brand machine mentioned previously for the first mode, over the temperature range from -7°C to +7°C.

[0083] The invention is likely to have industrial applications in the field of heat pumps and air conditioners.

[0084] Various modifications are within the reach of a person skilled in the art without departing from the scope of the present invention as described in the attached claims.

Claims

1. A heat pump comprising a closed circuit containing a refrigerant fluid and a lubricant, the closed circuit comprising a fluid compressor (1) and a return circuit for returning fluid to the compressor, the compressor extending in the closed circuit between a fluid inlet and a fluid outlet, the return circuit extending in the closed circuit, complementarily to the compressor, between the fluid outlet and the fluid inlet, the return circuit comprising a condenser (2), an expander (3) and an evaporator (4), said return circuit comprising a first line extending between the fluid outlet and the condenser, a second line extending between the condenser and the expander, a third line extending between the expander and the evaporator, and a fourth line extending between the evaporator and the fluid inlet, wherein the fluid comprises a mixture of an R32 first Freon (difluoromethane), an R125 second Freon (pentafluoroethane) and an R134a third Freon (1,1,1,2-tetrafluoroethane), and the lubricant comprises a synthetic polyolester oil, the pump being characterized in that said closed circuit comprises a first widening (5) of a line of the return circuit, the first widening (5) being positioned on said first line for imposing a negative pressure on drops of the lubricant to give rise to the appearance of gas bubbles in the drops that burst into finer droplets, thereby forming a mist of the lubricant between the compressor (1) and the condenser (2), the first widening (5) containing pipes (50) positioned vertically for selecting and transporting droplets created by the first widening (5).

2. The pump according to claim 1, wherein the closed circuit comprises a second widening (6) of a line of the return circuit.

3. The pump according to claim 2, wherein said second widening (6) is positioned on said second line.

4. The pump according to any one of the preceding claims, wherein the synthetic polyolester oil is of ISO VG 32 class.

5. The pump according to any one of the preceding claims, wherein the refrigerant fluid is an R407C Freon.

6. The pump according to any one of claims 1 to 4, wherein the refrigerant fluid is an R407A Freon.

7. The pump according to any one of the preceding claims, wherein said first widening (5) is positioned vertically.

8. The pump according to claim 7, wherein said first widening (5) is positioned vertically and with ascending fluid.

9. The pump according to claim 2 and any one of claims 3 to 8, wherein said second widening (6) is positioned vertically.

10. The use of a heat pump according to any one of claims 1 to 9, for the purposes of heating an enclosure, wherein the evaporator (4) is brought into thermal contact with the outside of the enclosure and the condenser (2) is brought into thermal contact with the inside of the enclosure in order to improve the thermodynamic efficiency of the heating operation.

11. The use of a heat pump according to any one of claims 1 to 9, for the purposes of cooling an enclosure, wherein the evaporator (4) is brought into thermal contact with the inside of the enclosure and the condenser (2) is brought into thermal contact with the outside of the enclosure in order to improve the thermodynamic efficiency of the cooling operation.

12. The use according to claim 10 or 11, wherein said refrigerant fluid is ascending in said first widening (5).