EP1766301B1 - Compact water/water heat pump core, and heat pump comprising same - Google Patents

Abstract

The whole set includes a compressor assembly ( 10 ), inlet ( 23 ) and outlet ( 24 ) to and from a harnessing loop, inlet ( 33 ) and outlet ( 34 ) to and from a heating loop, and two heat exchangers ( 20, 30 ), coupled to the compressor assembly and to the inlets and outlets. Linking pipes ( 21, 22, 31, 32 ) between heat exchangers and the compressor assembly, and/or inlets and outlets from and to harnessing and heating loops, are not linking pipes assembled by brazing but are welded stainless steel pipes, notably by orbital TIG welding. The whole set is enclosed in a tighten enclosure ( 40 ) comprising a supporting base ( 41 ) and a bonnet ( 42 ) sealed together.

Description

The invention relates to water / water type heat pumps.

This equipment makes it possible to capture the thermal energy available in the air, in the upper layers of the earth or in open water, to concentrate this energy and to return it in this concentrated form (at a higher temperature) to supply a hot water heating circuit.

By "water / water" is meant a type of heat pump in which the heat capture circuit and the heat return circuit (heating) are both liquid circulating circuits, as opposed to water / air systems. Or "air / air", it being understood that, depending on the needs, the water may be replaced or supplemented by another liquid. In particular, in the heat collection circuit water is often added ethylene glycol or other additive acting as antifreeze.

The advantage of a heat pump lies in the fact that the energy required for its power supply is lower than the energy returned in the heating circuit. The term "coefficient of performance" (COP) refers to the ratio between the energy returned and the energy consumed by the system, a ratio that can typically reach a value of 5 with the best systems currently available on the market.

More specifically, a heat pump comprises a compressor block and two heat exchangers respectively connected to the collection and heat recovery networks. The heat exchangers are also coupled to the compressor and the refrigerant circuit associated therewith, comprising a condenser, a pressure reducer and an evaporator. The compressor concentrates the captured energy on the condenser side and restores the energy to the heating circuit on the evaporator side.

The overall performance of the heat pump is even better than the heat exchange is complete and all the actions of the compressor and heat exchangers operate with the best possible thermal insulation vis-à-vis the environment outside.

The compressor, its associated refrigerant circuit as well as the two heat exchangers are grouped together in one and the same functional block, hereinafter referred to as "heat pump core", which constitutes an integrated assembly intended to be associated with the various elements of the heat capture and recovery circuits (piping, circulation pumps, thermostatic sensor, etc.) as well as 'to the power and control equipment of the system.

Such integrated sets are for example described by the EP-A-0 035 656 , DE-A-198 20 818 and WO-A-91/05977 . In heat pump hearts proposed so far, the various elements are interconnected by tubes assembled according to the usual techniques well known to heating and refrigeration.

More specifically, the connections between compressor and heat exchangers, and between heat exchangers and input / output ports of the collection and heat recovery networks, are made by means of copper tubes, assembled by soldering.

However, in the application to heat pumps, the use of copper tubes, and the assembly of tubes by brazing, is not without its disadvantages.

In the first place, copper is characterized by a high thermal conductivity, which is not sought in this application because it generates losses by heat exchange with the environment

Secondly, the assemblies made by brazing, if they guarantee a good seal, are not of a very high mechanical strength and corrosion. Indeed, as is known, brazing is to assemble different metals by providing a third metal (silver solder, in the case of a brazing) brought to a temperature above its melting point. Since the elements of the compressor are generally made of black steel and the exchangers are made of black steel or stainless steel, and these elements are connected to each other by copper tubes, we will find ourselves at the place of the brazed connections in the presence of continuity solutions steel / copper or stainless steel / copper, with further interposition of the filler metal.

But these connections are subject from the compressor to vibrations that would lead quickly to leaks or even damage in the case of too rigid assembly.

To avoid this collection, the copper bonds are generally made so as to provide the whole with a certain flexibility, thanks to rather long connections and / or a particular geometry (lyres, coils, etc.) to better disperse the stresses resulting in particular from the propagation of vibrations in the copper pipes.

Increasing the lengths of tubes, however, has the effect of increasing the exchange surface with the ambient atmosphere, thus the losses, and also unnecessarily increase the volume of refrigerant gas compressor circuit.

The object of the present invention is to remedy these drawbacks by proposing an optimized heat pump core both from the point of view of efficiency and compactness and reliability of operation.

The heat pump core of the invention is a pump core of water / water type as described above and disclosed by the EP-A-0 035 656 above, that is to say comprising, more precisely and in a manner known per se: a compressor block, comprising a closed circuit charged with refrigerant with compressor, condenser, expander and evaporator; an input socket and an output socket to a heat collection network; an input socket and an output socket to a heat transfer network; a first heat exchanger, coupled on the primary side to the evaporator of the compressor block and the secondary side to the taps of the heat collection network; and a second heat exchanger, coupled on the primary side to the condenser of the compressor block and on the secondary side to the outlets of the heat transfer network.

In a characteristic manner of the invention, the connecting pipes between the heat exchangers and the compressor block, and / or the connection pipes between the heat exchangers and the heat recovery and collection system taps are tubes of unbrazed connection, formed by welded stainless steel tubes.

By replacing the copper tubes used until now with steel tubes, and by replacing the brazed assemblies with welded joints, the various connections thus made within the heat pump core no longer present a continuity solution. which gives them a quality of mechanical resistance - especially to vibrations - and a quality of resistance to corrosion incomparably superior to what they were with brazed assemblies.

Indeed, in the case of welding, if it is well done, in terms of mechanical strength and sealing the result is equivalent to that of the original tube.

In particular, the vibrations generated by the compressor can not cause deterioration of these assemblies, and the mechanical strength, the geometry and the flexibility of the tubes and the stainless steel exchangers can be defined so as to absorb without rupture these vibrations by short links and small diameter, as opposed to the copper links used until now.

This dimensional reduction makes it possible to lower the thermal exchanges of the fluid with the environment, thus the losses, as well as the volume of refrigerant required. Moreover, in addition to the least exposed surface, heat exchange will also be reduced by the fact that steel is much less good heat conductor than copper and no bracket to the chassis is no longer necessary for the maintenance of exchangers (removal of thermal bridges when the heat exchangers are essentially devoid of such legs).

It is thus possible to significantly increase the coefficient of performance of the heat pump, typically from 1 to 2 points, that is to say that it becomes possible to achieve COP values of the order of 6 at 7, performance well above the best systems proposed so far.

The welding is advantageously performed by orbital TIG welding, which is a perfectly controlled technique that can be implemented automatically, thus with precise control of the various parameters and excellent reproducibility, again leading to an increase in overall reliability. of the device. In addition, the automatic TIG orbital welding makes it possible to limit to a minimum the temperature rise of the compressor body, thus avoiding any embrittlement thereof.

Preferably, the heat exchangers are stainless steel tubular exchangers.

This type of exchanger, which is perfectly suitable for a heat pump according to the invention where the various connections are soldered connections, can advantageously replace solder-assembled plate heat exchangers hitherto generally used in the field of pumps. heat. Even if they ensure a good heat exchange, plate heat exchangers are indeed fragile and do not support long water loaded with mineral salts, which can cause clogging by accumulation of deposits or solid impurities. Finally, their behavior in the presence of continuous vibrations remains limited.

Due to the considerable increase in reliability, it becomes unnecessary to provide a possibility of access to the various internal elements of the pump core after manufacture. These various elements (compressor block, heat exchangers, connecting pipes between heat exchangers and compressor block, and connection pipes between heat exchangers and heat recovery and capture network outlets) can therefore be confined in a chamber forming a single functional block. waterproof and isothermal.

This sealed confinement enclosure may in particular comprise a support base, supporting the compressor block and the heat exchangers, and a cover attached to this support base, the support base and the cover being permanently joined to each other, for example by welding if they are metal. It is understood that this "support base" may constitute all or part of any one or some of the faces of the assembly, and not only its lower part.

The residual free space of the confinement chamber may be filled with an insulating material, the support base then comprising an occultable orifice for introducing this insulating material.

The internal atmosphere of the confinement chamber may be under vacuum, or filled with an insulating dry gas, the support base then comprising an occultable orifice, in communication with said atmosphere, for the application of the vacuum or the introduction of the gas.

Preferably, the catches of the heat collection network, the outlets of the heat transfer network, and the said occultable port (s) are grouped on the support base.

The invention also covers, as such, a heat pump comprising, in combination, a pump core as above associated with coupling members, comprising at least one circulator, a heat capture circuit and a heat recovery circuit, as well as thermal regulating members, and power supply members of the assembly.

An example of a heat pump made according to the teachings of the invention will now be described, with reference to the attached single figure which is a schematic view, in cavalier perspective, of the various elements constituting this pump core.

In the figure, reference numeral 10 denotes the compressor unit, which is an assembly with a closed circuit, charged with refrigerant, comprising a compressor 11, an evaporator 12, a condenser 13 and a pressure regulator 14. The compressor motor is for example an electric motor powered from the outside by the mains.

A first heat exchanger 20 is coupled on the primary side to the evaporator 12 of the compressor block 10 via two links 21 and 22. On the secondary side, it is connected to receptacles 23, 24 for fluid inlet and outlet intended to be connected. a heat collection network; the connections to the sockets 23, 24 are made by pipes 25, 26.

A second heat exchanger 30 is coupled on the primary side to the condenser 13 of the compressor block 10 via two links 31 and 32. On the secondary side, it is connected to fluid inlet and outlet taps 33, 34 intended to be connected to a heat transfer network (heating network); the connections to the taps 33, 34 are produced by tubes 35, 36.

The exchangers 20 and 30 are preferably twisted tubular exchangers made of welded stainless steel, the size of which is adapted to the power of the compressor to guarantee optimum exchange both towards the heating circuit and from the heat capture circuit.

In a characteristic manner of the invention, the links 21, 22, 31, 32 between the compressor 10 and the heat exchangers 20 and 30, as well as the connections 25, 26, 35, 36 between the exchangers 20 and 30 and the sockets 23, 24, 33, 34 inlet and outlet networks of heat capture and return, are provided by means of welded stainless steel tubes. The The diameter of these tubes is optimized to ensure this connection without creating any obstacle for the fluid (refrigerant, or fluid flowing in the networks), with a length and a geometry studied to achieve this connection by the shortest path possible. In addition, thanks to the excellent mechanical strength of the welded connections, the exchangers can be simply suspended by the tubes 21, 22, 25, 26 (or 31, 32, 35, 36, respectively), which hold them in place without having to it is necessary to provide support for mounting brackets to the frame or similar means, thermal bridge generators.

A small diameter tube 16, which may also be made of spiral or multispire-shaped stainless steel, provides sealed access for refrigerant charging of the compressor and control of this charge. Outside the enclosure, this stainless steel tube may be extended with a copper tube allowing the connection to the reserve of refrigerant gas by methods commonly used by refrigeration.

The various elements of the heat pump core that have just been described are grouped inside a housing 40 consisting of a support base 41 and a cover 42. Advantageously, all the inputs and outputs that are useful and all access to the elements of the pump core are grouped at the support base 41, including the sockets 23, 24, 33, 34 to the heat capture and recovery networks. There is also the crossing 43 for the power supply of the compressor 11, as well as a concealable orifice 44 allowing communication with the interior volume of the enclosure once the hood 42 is closed, and a passage 45 for the pipe 16 of the charge of the refrigerant. On the figure 1 the support base occupies the whole lower part of the whole. But it can also occupy all or part of any one or some faces of the assembly, as needed in the realization of the heat pump.

The cover 42 can therefore be easily sealed, formed in one piece, for example metal, without any crossing. It can be sealed to the support base 41 to form an envelope completely isolating the heat pump core from its environment. When the cover and the support base are both made of metal, this waterproof fastening can even be advantageously achieved by welding of the two elements so as to constitute a single functional block, not removable. Other permanent joining solutions may be envisaged, for example gluing, when the cover and / or base support are not made of a metal material suitable for welding.

Advantageously, after closure of the casing, an insulating material is introduced through the orifice 44 to completely fill the internal volume of the pump core, for example a powdery material or an expandable foam, which will minimize the undesirable thermal exchanges and increase all the performance of the system. In addition, this lining reduces the transmission of mechanical and acoustic vibrations produced by the compressor to the outside.

After filling, the sealed enclosure can finally be drawn to vacuum or filled with a dry gas providing better thermal insulation characteristics than air, for example argon or sulfur hexafluoride.

Finally, for the case where the support base consists of the lower face and to the extent that the tubes 26 and 36 leading to the respective high points of the heat and heating capture circuits are not bent, it is possible to sliding purge systems comprising an automatic trap 46 connected to a pipe 48 terminating at the bottom, outside the block 40, by a vent 50 mounted on a sleeve 52 fitted at the mouth of the homologous pipe 26 or 36. These systems purge, placed from the outside (as can be seen in the exploded view of the figure), can be easily replaced later, if necessary.

Claims (12)

1. A water loop heat pump core, comprising :

   - a compressor assembly (10), comprising a closed circuit of cooling gas with a compressor (11), a condenser (13), an expander (14) and a vaporiser (12),

   - an inlet (23) and an outlet (24) from and to a harnessing loop,

   - an inlet (33) and an outlet (34) from and to a heating loop,

   - a first heat exchanger (20), coupled on its primary side to the vaporiser of the compressor assembly and on its secondary side to the inlet and outlet of the harnessing loop, and

   - a second heat exchanger (30), coupled on its primary side to the condenser of the compressor assembly and on its secondary side to the inlet and outlet of the heating loop,

   characterised in that the linking pipes (21, 22, 31, 32) between the heat exchangers and the compressor assembly, and/or the linking pipes (25, 26, 35, 36) between the heat exchangers and the inlets and outlets of the harnessing and heating loops, are non-brazed linking pipes which are made from welded stainless steel pipes.
2. The heat pump core of claim 1, wherein the stainless steel pipes are welded by orbital TIG welding.
3. The heat pump core of claim 1, wherein the heat exchangers (20, 30) are stainless steel tubular exchangers.
4. The heat pump core of claim 1, wherein the compressor assembly, the heat exchangers, the linking pipes between the exchangers and the compressor assembly, and between the exchangers and the inlets and outlets of the harnessing and heating loops, are enclosed inside a tight containment enclosure (40).
5. The heat pump core of claim 1, wherein the exchangers are essentially without support brackets for attaching them to the supporting frame.
6. The heat pump core of claim 1, wherein the containment enclosure (40) comprises a supporting base (41) forming at least part of at least one side of the assembly, supporting the compressor assembly and the heat exchangers, and a bonnet (42) mounted onto said supporting base.
7. The heat pump core of claim 6, wherein the supporting base (41) and the bonnet (42) are attached together in a permanent manner.
8. The heat pump core of claim 6, wherein the remaining free space inside the containment enclosure is filled with an insulating material, and the supporting base (41) includes an occlusive aperture (44) to introduce said insulating material.
9. The heat pump core of claim 6, wherein vacuum has been applied to the internal atmosphere of the containment enclosure, and the supporting base (41) includes an occlusive aperture (44) in communication with said atmosphere to apply said vacuum.
10. The heat pump core of claim 6, wherein the internal atmosphere of the containment enclosure is filled with a dry insulating gas, and the supporting base (41) includes an occlusive aperture (44) in communication with said atmosphere to introduce said gas.
11. The heat pump core of any one of claims 8 to 10, wherein the inlets and outlets (23,24) of the harnessing loop and the inlets and outlets (24, 34) of the heating loop, and said occlusive aperture(s) (44) are all grouped on said supporting base (41).
12. A heat pump, characterised by including, in combination :

    - a pump heart according to at least one of claims 1 to 11,

    - coupling members, including at least one circulating pump, to a harnessing loop,

    - coupling members, including at least one circulating pump, to a heating loop,

    - thermal regulating means, and

    means for supplying electricity to the assembly.

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