FR2993963A1 - Thermodynamic water heater for heating domestic supply water, has heat pump comprising refrigerant circuit that includes insulation unit in upstream and downstream of condenser to insulate condenser with respect to rest portion of circuit - Google Patents

Abstract

The water-heater (10) has a cylindrical tank (11) provided with a heat pump (14) that includes a refrigerant circuit (15) traversed by a refrigerant. The circuit traverses a metal condenser (16) located inside the tank. The circuit includes an electric insulation unit in upstream and downstream of the condenser to insulate the condenser with respect to rest portion of the circuit. The electric insulation unit comprises a dielectric sleeve connecting the condenser to rest portion of the circuit. The sleeve has a central tubular part connected to ends of a tube and made of dielectric material.

Description

The present invention relates to a thermodynamic water heater for heating domestic hot water.

Typically, a thermodynamic water heater is a water heater comprising a tank equipped with a heat pump as a heating means. The principle of a heat pump is to take calories from a source, for example outside air, to transfer them to the water contained in the tank of the water heater.

Such a heat pump comprises a circuit, traversed by a refrigerant. A refrigerant is a substance capable of absorbing and returning heat by changes in the liquid / gas or gas / liquid state. The refrigerant circuit of the heat pump forms a loop through an evaporator in which the fluid takes heat from a source, for example outside air, the refrigerant then changes from the liquid state to the state gaseous; a compressor powered by a motor, which raises the pressure and temperature of the gaseous refrigerant by compressing it; a condenser made of metal, for example copper, situated inside the tank, in contact with water, in which the refrigerant passes in the liquid state by yielding its heat to the water to be heated; and a regulator that reduces the pressure and temperature of the refrigerant in the liquid phase. Such a water heater is for example described in document FR 2 963 415.

Typically, the tank of the water heater is made of enamelled steel, so as to prevent oxidation, and thus the degradation by corrosion of said tank. However, it happens that the enameling of the tank has defects, thus limiting the protection against oxidation of said tank.

A known solution is to set up, inside the tank, in contact with water, a means of protecting the tank against oxidation, such as an anode with imposed current or sacrificial anode magnesium . The anode reacts with the tank, which then forms a cathode, so as to lower a redox potential of the tank to a level such that the oxidation of said tank does not occur.

However, the condenser is connected to the electrical ground via the motor operating the compressor, and the oxidation-reduction potential of the copper is higher than that of the steel. As a result, the condenser senses the current generated by the anode, thereby inhibiting the antioxidant protection of the vessel.

There is therefore a need to prevent the condenser from sensing the current generated by the anode. A first solution envisaged is to use, for the manufacture of the condenser, a material other than copper, meeting the requirements for sanitary water, and not disturbing the anti-oxidation protection set up for the tank. The enamelled steel corresponds for example to the aforementioned constraints. However, the manufacture of an enameled steel condenser is delicate and involves a cost that is too high. A second solution considered is to coat the condenser with an electrical insulator such as paint. However, such a coating seems difficult to implement, especially since it involves significant risks of degradation due to the conditions of use of the condenser and must meet sanitary standards. The present invention aims to provide an alternative solution to the technical problem.

More specifically, an object of the present invention is a water heater comprising a tank provided with a heat pump, said heat pump comprising a circuit traversed by a refrigerant, said circuit passing in particular a metal condenser located at the interior of the tank, said circuit comprising upstream and downstream of the condenser a first means of electrical insulation of said condenser relative to the remainder of the refrigerant circuit.

Such a water heater has the advantage of having a condenser electrically isolated from the rest of the circuit of the heat pump. Such a water heater is particularly useful in the case where said water heater is provided with a means of protecting the tank against oxidation.

Preferably, the first electrical insulation means each comprise a dielectric sleeve connecting the condenser to the rest of the refrigerant circuit. According to one embodiment of the invention, the sleeve comprises a central tubular portion of dielectric material connected on each side by a tube, an end of each of said tubes comprising at least a substantially conical or frustoconical portion substantially disposed along the axis of said tube, the sleeve further comprising a clamping means of the tubular portion on each of said ends. According to another embodiment of the invention, the sleeve comprises a first tube and a second tube fixed to each other, one end of the second tube being inserted into the first tube, said end being provided with at least a substantially tubular dielectric element disposed between an inner wall of the first tube and an outer wall of the second tube.

Such electrical isolation means have the advantage, in addition to electrically decoupling the condenser and the rest of the circuit of the heat pump, to meet the mechanical and sealing constraints on the circuit of the heat pump and the use of the refrigerant.

The invention also relates to a water heater comprising a tank provided with a heat pump, said heat pump comprising a circuit traversed by a refrigerant, said circuit passing through a metal condenser located inside the tank, the condenser being attached to the tank via a fastening means provided with a second means of electrical insulation of the condenser relative to the tank.

The use of an electrical insulation means associated with the means of fixing the condenser on the tank has the advantage of achieving an electrical decoupling between the condenser and the tank, particularly useful when the water heater is provided with a means of protection of the tank against oxidation. The invention relating to the electrical decoupling of the tank and the condenser is advantageously combined with the invention relating to the electrical decoupling of the condenser and the rest of the circuit of the heat pump. According to one embodiment of the invention, the condenser is integral at the inlet and at the outlet of a support connected to the tank via the fastening means provided with the second electrical insulation means, said support comprising a surface substantially parallel to the tank on which is disposed, between the support and the tank, a third means of electrical insulation of the support relative to the tank, so that said support and said tank are not in contact with each other; other. Such an embodiment of the invention is particularly advantageous when the condenser is connected to the rest of the circuit of the heat pump in the upper part of the tank. According to another embodiment of the invention, the fastening means is integral with the tank and has substantially the shape of a hollow cylinder passing through a wall of the tank, said fixing means being configured so as to receive the condenser in input and output, the second electrical isolation means forming a layer between the fixing means and the circuit, so that the fastening means and the condenser are not in contact with each other. Such an embodiment of the invention is particularly advantageous when the condenser is connected to the rest of the circuit of the heat pump in the lower part of the tank. The invention also relates to a dielectric sleeve for a water heater as previously described, comprising a central tubular portion of dielectric material connected on each side by a tube, a first end of each of said tubes comprising at least a substantially conical portion or frustoconical substantially disposed along the axis of said tube, the sleeve further comprising a clamping means of the tubular portion on each of said first ends, a second end of one of the tubes being adapted to be connected to the condenser, and a second end of the other of the tubes being adapted to be connected to the rest of the circuit of the heat pump. The invention also relates to a dielectric sleeve for a water heater as previously described, comprising a first tube and a second tube fixed to each other, a first end of the first tube being able to be connected to the condenser , a first end of the second tube being adapted to be connected to the remainder of the circuit, a second end of the second tube being inserted into the first tube, said second end being provided with at least one substantially tubular dielectric element disposed between an inner wall of the first tube and an outer wall of the second tube. The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These are given as an indication and in no way limitative of the invention. The figures show: - Figure 1: a schematic sectional view of a water heater with a heat pump according to one embodiment of the invention; - Figure 2: a sectional view of an electrical insulation means of the water heater according to one embodiment of the invention; - Figure 3: a sectional view of an electrical insulation means of the water heater according to another embodiment of the invention than that shown in Figure 2; - Figure 4: a detail view, in section, of an assembly between a condenser and a tank of the water heater according to one embodiment of the invention; 5 is a detail view, in section, of an assembly between the condenser and the vessel according to another embodiment of the invention than that presented in FIG. 4. FIG. schematic, in section, of a water heater 5 10 according to one embodiment of the invention. The water heater 10 comprises a tank 11 of substantially cylindrical shape along a vertical axis. Figure 1 shows a section of the water heater 10 in a vertical plane. The tank 11 is connected to a domestic water circuit via an inlet 12 and an outlet 13. Preferably, the inlet 12 and the outlet 13 are located respectively in the lower part and in the upper part of the tank 11. hot water is less dense than cold water and tends to rise to the top of the tank. The water heater 10 is connected to a heat pump system 14 for heating the water in the tank 11. Said system comprises a circuit 15 traversed by a refrigerant. The circuit 15 passes in particular through a condenser 16 of metal, which serves for the heat exchange between the refrigerant and the water of the tank 11. The condenser 16 is for example copper. The condenser 16 is placed inside the tank 11. In the example shown in FIG. 1, the condenser 16 is connected to the remainder of the circuit 15 in the upper part of the tank 11. However, the condenser 16 can also be connected to the rest of the circuit 15 in the lower part of the tank 11 or even on a side part. The water heater 10 is further provided with a means 161 for protecting the tank 11 against oxidation, disposed inside said tank, in contact with water. The protection means 161 is, for example, an imposed current anode or a sacrificial magnesium anode. The circuit 15 comprises, upstream and downstream of the condenser 16, a first means (17, 18) for electrically isolating said condenser from the rest of the circuit 15.

In the example shown in FIG. 1, the first electrical insulation means (17, 18) are arranged outside the tank 11. However, the first electrical insulation means (17, 18) can also be disposed within the vessel, especially above a maximum level of water. The first means (17, 18) of electrical insulation are substantially identical. Preferably, the first electrical insulation means (17, 18) are dielectric sleeves connecting the condenser 16 to the remainder of the circuit 15. FIG. 2 shows a sectional view of the sleeve 17 according to one embodiment of the invention.

The sleeve 17 has a central tubular portion 19 made of a dielectric material. The tubular portion 19 is for example plastic. The tubular portion 19 is connected at each end to a tube (20, 21) of metal, such as copper or brass. The tubes (20, 21) are substantially identical.

A first end (22, 23) of each of the tubes (20, 21) is inserted into the tubular portion. The first end (22, 23) of each of the tubes (20, 21) comprises at least one substantially conical or frustoconical portion 24 disposed along the axis of said tube (20, 21), a flared portion of said at least one cone or trunk cone protruding substantially from an outer wall 241 of said tube (20, 21). In the example, the first ends (22, 23) each comprise three substantially frustoconical portions 24 forming fir-shaped flutes. Preferably, the at least one substantially conical or frustoconical portion 24 is arranged so that a narrow portion of said at least one cone or truncated cone is proximal. The sleeve 17 further comprises means (25, 26) for clamping the tubular portion 19 on each of the first ends (22, 23) of the tubes (20, 21), so as to seal said sleeve and thereby prevent refrigerant leaks.

In the example shown in Figure 2, the means (25, 26) for clamping are aluminum crimping rings. In the example, a second end (27, 28) of one of the two tubes (20, 21) is welded or brazed to the capacitor 16, and a second end (28, 27) of the other two tubes (21, 20) are welded or brazed to the rest of the circuit 15. Figure 3 shows a sectional view of the first sleeve 17 according to another embodiment of the invention. The first sleeve 17 comprises a first tube 70. The first tube 70 is connected at a first end 71 to the condenser 16, for example by welding or brazing. An outer wall 72 of the first tube 70 is provided at a second end 73 with a peripheral projection 74. The sleeve 17 further comprises a second tube 75. The second tube 75 is connected at a first end 76 to the remainder of the circuit 15, for example by welding or brazing. A second end 77 of the second tube 75 is inserted into the first tube 70. An outer wall 78 of the second end 77 of the second tube 75 is provided with at least a first substantially tubular dielectric member (79, 80). Preferably, the at least one first dielectric element (79, 80) is an O-ring. In the example shown in FIG. 3, the outer wall 78 of the second end 77 of the second tube 75 is provided with two substantially identical first dielectric elements (79, 80). A radial dimension of the first dielectric elements (79, 80) is defined such that said first dielectric elements are simultaneously in contact with the outer wall 78 of the second end 77 of the second tube 75 and an inner wall 81 of the first tube 70. In this manner, the first dielectric elements (79, 80) electrically isolate the first tube 70 from the second tube 75, and block the passage of the refrigerant between the first and second tubes (70, 75). Preferably, the first dielectric elements (79, 80) are each disposed in a groove (82, 83) in the outer wall 78 of the second tube 75.

The first and second tubes (70, 75) are fastened together via a clamping means 84. In the example shown in FIG. 3, the clamping means 84 is a dielectric nut. A first diameter 85 of the nut 84 is substantially equal to an outer diameter of the first tube 70. A second diameter 86 of the nut 84 is substantially equal to an outer diameter of a central portion 87 of the second tube 75, the diameter outside the central portion 87 being greater than the outer diameter of the first tube 70. A thread of the nut 84 disposed at the second diameter 86 cooperates with a thread of the central portion 87 of the second tube 75. In this way, the nut 84 engages the projection 74 of the first tube 70 against the central portion 87 of the second tube 75. The first sleeve 17 further comprises a second substantially tubular dielectric element 88 disposed between the projection 74 of the first tube 70 and the central portion 87 of the second tube 75. The second dielectric element 88 makes it possible to electrically decouple between the first and second tubes (70, 75), when the nut 84 is tightened. Embodiments of the invention shown in FIGS. 2 and 3 enable electrical decoupling between the condenser 16 and the remainder of the circuit 15, which is particularly necessary in the case where the tank 11 is provided with a means of protection against leakage. oxidation comprising a forced current anode or a sacrificial anode. The sleeve 17 shown in Figures 2 and 3 also meets the mechanical strength and sealing requirements imposed by the circuit 15 of the heat pump 14 and the use of the refrigerant.

Figure 4 shows a detailed view of an assembly of the condenser 16 and the tank 11 according to one embodiment of the invention. This embodiment is particularly suitable when the condenser 16 is connected to the remainder of the circuit 15 in the upper part of the tank 11, as in the example shown in FIG. 1. The water heater 10 further comprises a means 29 for fixing the condenser 16 to the tank 11 provided with a second means 30 for electrically insulating said condenser with respect to said tank. The condenser 16 is integral, at the inlet and at the outlet, with a support 31 made of metal disposed near an internal surface 32 of the vessel 11. The support 31 is secured to the condenser 16, for example by welding. A surface 33 of the support 31, disposed opposite the inner surface 32 of the tank 11, is substantially parallel to said inner surface of the tank 11. The support 31 is connected to the vessel 11 via the fixing means 29 provided with the second means 30 of electrical insulation. Preferably, the fixing means 29 connects the support 31 to the tank 11 at a central point substantially disposed between the inlet and the outlet of the condenser 16, so as to balance the forces. In the example shown in FIG. 4, the fixing means 29 is a threaded screw cooperating with a first hole 34 opening out of the tank 11 and a second blind hole 35 of the support 31. A threading of the second hole 35 corresponds to the threading The second means 30 of electrical insulation is a washer of dielectric material configured to cooperate with the screw 29 and the first hole 34 of the tank 11. The washer 30 20 electrically isolates the screw 29 of the tank 11, and thus to electrically isolate the condenser 16 of said tank. The washer 30 is for example plastic. The surface 33 of the support 31 furthermore accommodates a third means 36 for electrically isolating the support 31 with respect to the vessel 11, so that the support 31 and the vessel 11 are not in contact with each other. . Preferably, the third electrical isolation means 36 is in contact with the surface 33 of the support 31 and the internal surface 32 of the tank 11, when the screw 29 is clamped in the second hole 35. In the example presented in FIG. 4, the support 31 is provided with a peripheral groove 37 receiving full length the third means 36 of electrical insulation. The peripheral groove 37 is for example circular.

Figure 5 shows a detail view of an assembly of the condenser 16 and the tank 11 according to a variant. This embodiment is particularly suitable when the condenser 16 is connected to the remainder of the circuit 15 in the lower part of the tank 11.

The water heater 10 further comprises a means 49 for fixing the condenser 16 to the tank 11 provided with a second means 50 for electrically insulating said condenser with respect to said tank. The fixing means 49 is substantially in the form of a hollow cylinder passing through a wall 51 of the vessel 11, preferably of circular section. The fixing cylinder 49 is made of metal, for example enamelled steel. In the example shown in FIG. 5, the fixing cylinder 49 passes through the wall 51 of the tank 11 vertically. However, the fixing cylinder 49 can also pass through the wall 51 of the tank 11 with an inclination with respect to the vertical.

The fixing cylinder 49 is integral with the tank 11. The fixing cylinder 49 is secured to the vessel 11, for example by welding. In the example shown in FIG. 5, a fixing cylinder 49 is associated with the condenser 16 at the inlet, and another identical fixing cylinder 511 is associated with the condenser 16 at the outlet, the two fixing cylinders (49, 511) being each provided with third substantially identical electrical insulation means (50, 512). In a variant, the fixing cylinder 49 is configured to receive the condenser 16 at the inlet and at the outlet. The second means 50 of electrical insulation forms a layer between the fixing cylinder 49 and the condenser 16, so that the condenser 16 and the fixing cylinder 49 are not in contact with each other. Preferably, the second means 50 of electrical insulation has substantially the shape of a hollow cylinder. An outer wall 52 of the electrical insulation cylinder 50 is substantially complementary to an inner wall 53 of the fixing cylinder 49.

In the example shown in FIG. 5, an internal wall 54 of the electrical insulation cylinder 50 has a shape substantially complementary to an external wall 55 of the capacitor 16. In a variant, the internal wall 54 of the insulation cylinder 50 electrical 5 has a shape substantially complementary to an external wall of the condenser 16 at the inlet and an external wall of the condenser 16 at the outlet. The outer wall 52 of the electrical insulation cylinder 50 has a first peripheral protrusion 56, disposed in abutment against a first end 57 of the fixing cylinder 49, disposed outside the vessel 11. Preferably, when the condenser 16 is connected to the remainder of the circuit 15 in the lower part of the tank 11 or laterally, the cylinder 50 of electrical insulation is fixed to the fixing cylinder 49 by means of a clamping means 58, arranged at the first end 57 of said fixing cylinder. In the example shown in FIG. 5, the clamping means 58 is a metal nut, for example made of steel or brass. A first diameter 581 of the nut 58 is substantially equal to an outside diameter of one end of the electrical insulation cylinder 50 disposed outside the tank 11. A second diameter 582 of the nut 58 is substantially equal to an outer diameter of the first end 57 of the fixing cylinder 49. A thread of the nut 58 disposed at the second diameter 582 cooperates with a thread of the fixing cylinder 49 disposed at the first end 57 of said fixing cylinder. In this way, the nut 58 tightens the first projection 56 of the electrical insulation cylinder 50 against the first end 57 of the fixing cylinder 49, so as to seal the tank 11 at the level of said fixing cylinder. . Preferably, the insulating cylinder 50 is made of a compressible dielectric material, such as rubber. In this way, when the nut 58 exerts pressure on the insulating cylinder 50, at the first projection 56, the inner wall 54 of said isolation cylinder comes into contact with the outer wall 55 of the condenser 16, thus ensuring the seal between the water of the tank 11 and the outside. Likewise, a thickness of the insulating cylinder 50 is defined so that the inner surface 53 of the fixing cylinder 49 compresses the insulating cylinder 50 against the condenser 16. In this way, the outer wall 52 of the cylinder 50 insulation is in contact with the inner surface 53 of the fixing cylinder 49, thereby sealing between the water of the tank 11 and the outside. Preferably, when the condenser 16 is connected to the remainder of the circuit 15 in the lower part of the tank 11 or laterally, the electric insulation cylinder 50 comprises two parts (59, 60), a first part 59 being arranged close to the first end 57 of the fixing cylinder 49, and a second portion 60 being disposed near a second end 61 of said fixing cylinder opposite said first end. The first portion 59 is for example rubber, and the second portion 60 is for example plastic.

In the example shown in Figure 5, the outer wall 52 of the second portion 60 is provided with a second peripheral projection 62, disposed in abutment against the second end 61 of the cylinder 49 fixing. The second projection 62 thus improves the sealing of the vessel 11 at the cylinder 49 fixing.

The embodiments of the invention presented in FIGS. 4 and 5 enable electrical decoupling of the condenser 16 and the tank 11, particularly useful in the case where the tank 11 is provided with a means of protection against oxidation. comprising an imposed current anode or a sacrificial anode.

Claims (4)

CLAIMS1 - Water heater (10) comprising a tank (11) provided with a heat pump (14), said heat pump comprising a circuit (15) traversed by a refrigerant, said circuit passing in particular a condenser (16) of metal located inside the tank, said water heater being characterized in that the circuit comprises upstream and downstream of the condenser a first means (17, 18) of electrical insulation of said condenser relative to the rest of the circuit of refrigerant. 2 - water heater according to claim 1, wherein the first electrical insulation means each comprise a dielectric sleeve connecting the condenser to the rest of the refrigerant circuit. 3 - water heater according to claim 2, wherein the sleeve comprises a central tubular portion (19) of dielectric material connected at each end to a tube (20, 21), an end (22, 23) of each of said tubes comprising at least one portion (24) substantially conical or frustoconical substantially disposed along the axis of said tube, the sleeve further comprising means (25, 26) for clamping the tubular portion on each of said ends. 4 - water heater according to claim 2, wherein the sleeve comprises a first tube (70) and a second tube (75) fixed to one another, one end (77) of the second tube being inserted into the first tube, said end being provided with at least one substantially tubular dielectric element (79, 80) disposed between an inner wall (81) of the first tube and an outer wall (78) of the second tube. - Water heater according to one of claims 1 to 4, wherein the condenser is fixed to the vessel via a means (29, 49) for fixing provided with a second means (30, 50) of electrical insulation of the condenser with respect to the tank. 6 - water heater according to claim 5, wherein the condenser is integral at the inlet and outlet of a support (31) connected to the vessel via the means (29) for fixing provided with the second means (30). electrical insulation, said support having a surface (33) substantially parallel to the tank on which is disposed, between the support and the tank, a third means (36) of electrical insulation of the support relative to the tank, so said support and said vessel are not in electrical contact with each other. 7 - water heater according to claim 5, wherein the means (49) for attachment is integral with the vessel and has substantially the shape of a hollow cylinder passing through a wall (51) of the vessel, said fixing means being configured so as to receive the inlet and outlet condenser, the second means (50) of electrical insulation forming a layer between the fixing means and the circuit, so that the fixing means and the condenser are not in contact electric with each other. 8 - Sleeve (17, 18) dielectric for a water heater (10) according to one of claims 2 to 3 and 5 to 7, comprising a central tubular portion (19) of dielectric material connected at each end to a tube ( 20, 21), a first end (22, 23) of each of said tubes comprising at least one substantially conical or frustoconical portion (24) substantially disposed along the axis of said tube, the sleeve further comprising means (25, 26) for clamping the tubular part on each of said first ends, a second end (27, 28) of one of the tubes (20, 21) being able to be connected to the condenser, and a second end (28, 27) of the other tubes (21, 20) being able to be connected to the rest of the circuit of the heat pump. 9 - Sleeve (17, 18) dielectric for a water heater (10) according to one of claims 2 and 4 to 7, comprising a first tube (70) and a second tube (75) attached to one other, a first end (71) of the first tube being able to be connected to the condenser (16), a first end (76) of the second tube being able to be connected to the remainder of the circuit (15), a second end (77) the second tube being inserted into the first tube, said second end being provided with at least one substantially tubular dielectric element (79, 80) disposed between an inner wall (81) of the first tube and an outer wall (78) of the second tube .