EP4372288A1

EP4372288A1 - Heat pump system comprising one or more devices designed to block any refrigerant leaks

Info

Publication number: EP4372288A1
Application number: EP23204397.6A
Authority: EP
Inventors: Lorenzo Marra
Original assignee: Ariston SpA
Current assignee: Ariston SpA
Priority date: 2022-11-18
Filing date: 2023-10-18
Publication date: 2024-05-22
Also published as: FR3142238A3

Abstract

The object of the present invention is a heat pump system (1) comprising at least one refrigeration circuit (2) in which a refrigerant fluid circulates and operates at the primary side (24) of a main heat exchanger (21), one conditioning circuit (3) in which a technical fluid, used for room heating/cooling functions and/or for the production of domestic water, circulates and operates at the secondary side (25) of said same main heat exchanger (21). Said conditioning circuit (3) comprises at least one circulation pump (30) for said technical fluid, one or more terminals (31) for room heating/cooling and/or for the production of domestic water, and one safety valve (5) capable of being crossed by said technical fluid and of closing in case of refrigerant fluid leakage flows in said conditioning circuit (3) in opposite direction (FR) to that of operation (F) of the said technical fluid.

Description

The object of the present invention is a heat pump system for room heating/cooling functions and/or for the production of domestic water and preferably operating with low environmental impact refrigerants.
More precisely, the object of the present invention is a heat pump system for room heating/cooling functions and/or for the production of domestic water arranged to prevent any refrigerant leaks from spreading internally into the environment in which said heat pump system is installed and/or operates.
Even more precisely, the object of the present invention is a heat pump system for room heating/cooling functions and/or for the production of domestic water comprising one or more devices adapted to prevent said possible refrigerant leaks from reaching the room heating or domestic water production system. Without any limiting intent, the invention therefore falls within the sector of heat pump conditioning equipment for residential and/or industrial/commercial buildings (or the like), where "conditioning" is indifferently referred to as "heating" or "cooling", preferably made by electrical power supply.
Naturally, nothing prevents the heat pump system of the invention from being extended, with minimal adaptations within the reach of the man skilled in the art, to sectors similar to those of the heating and/or cooling equipment, for example within the scope of the heat pumps for the production of domestic water.
It is known that a heat pump system comprises at least:

one "refrigeration circuit" in which a refrigerant is evaporated at low temperature, brought to high pressure, condensed and finally brought back to an evaporation pressure, and
one "conditioning circuit" of a technical fluid, preferably water or the like, that may be used for room heating/cooling via radiators, floor radiant panels, fan coils or the like and/or for the production of domestic hot water via special heat accumulators, e.g. hot water storages.

Generally, the refrigeration circuit and the conditioning circuit share at least one heat exchanger in which the heat exchange between the relative refrigerating and technical fluids is carried out.
More precisely, when a heat pump system is used for the ambient and/or domestic water heating, said heat exchanger operates as a condenser.
On the contrary, if the same heat pump system operates in cooling mode, said heat exchanger operates as an evaporator.
It is known that the development of the heat pumps must face a plurality of both technical and environmental challenges.
On one hand, in fact, it is desired that the heat pump continues to operate in the most efficient possible way, while, on the other, it is increasingly desired to avoid the use of highly polluting refrigerants so as to reduce the environmental risk (e.g. for contrasting phenomena such as the global warming).
In order to meet such intents, the most polluting refrigerants, such as the common R410A, are being progressively replaced with others having a low environmental impact (i.e. having a low "Global Warming Potential" or "GWP"). For example, more and more frequently the heat pumps operate with refrigerants belonging to the group of hydrofluorocarbons and/or aliphatic hydrocarbons such as, without any limiting intent, propane R290 (chemical formula: CsHs) or R32 (a difluoromethane having chemical formula CH₂F₂). Such refrigerants (or others belonging to the same families or similar groups), although having a low environmental impact, are not free from drawbacks.
In fact, it is known that low environmental impact refrigerants are generally highly flammable.
Therefore, during the transition from traditional to low GWP refrigerants it has been necessary to pay greater attention to their flammability and related problems.
For example, it was necessary to prevent refrigerant leaks, deriving from possible defects and/or breakages of one or more components of the heat pump system, from reaching and/or spreading internally to the installation and/or usage environment (e.g., in a building room or in a technical room), where the formation and accumulation of high concentrations of potentially flammable and/or explosive refrigerant would pose risks to the safety of the users and/or to the structural integrity of the buildings.
In order to avoid such dangers, the most recent heat pump systems using low GWP refrigerants have been appropriately arranged to block possible refrigerant leaks and escapes before they reach the conditioning circuit and spread into the installation and/or usage environment of the same heat pump system.
For example, said heat pump system has been equipped with a degasser device capable of stopping the flow of the technical fluid (e.g. of the technical water) towards the conditioning circuit in presence of refrigerant leaks and of preventing the spreading thereof in the direction of the operating flow, or in the opposite direction, in any case adapted to prevent said refrigerant leaks from reaching pipes, manifolds, valves, radiators, fan coils or any other device used to make the technical fluid distribution circuit inside a building.
A first example of a known degasser device is shown and described in document EP 3 734 197 A1 .
Since it shall be referred to several times during this description, it should be noted that "operating flow" or "operating direction" shall be referred to as the direction normally imparted to the technical fluid by a circulation pump of the conditioning circuit when the heat pump system operates in heating and/or cooling conditions (for greater clarity, see also Fig. 1, where, by way of a non-limiting example, said "operating flow or direction" is represented by the arrow F).
The prior art document DE102020103743B4 shows, by way of an example, a further known degasser device of the type comprising a float appropriately designed for stopping the operating flow of the technical fluid when the extent of the refrigerant leaks are greater than a predefined and normally tolerated value. As a further safety measure, said degasser device may be placed, or at least directly communicating, with the external environment so as to allow said refrigerant leaks to be discharged into the atmosphere.
Said heat pump systems may be further equipped with special and well-known valves, generally non-return valves (also referred to as "check" or "anti-flooding") which prevent said refrigerant leaks and escapes from flowing towards the conditioning circuit in opposite direction to that of operation of the technical fluid, i.e., as opposed to the circulation pump.
Such measure is also shown and described in the same document DE102020103743B4 where, in fact, a well-known check valve is positioned in the conditioning circuit between the circulation pump and the heat exchanger arranged for the heat exchange between refrigerant and technical fluid. A similar expedient is also shown, for example, even in the prior art documents US 2019/346191 A1 , EP 3 789 686 A1 , US 2019/301750 , CN 1 133 045 C .
If on one hand the use of a check valve increases the safety of a heat pump system against possible refrigerant leaks, on the other hand it introduces and generates strong localised load losses and therefore a significant resistance to the circulation of the technical fluid in the conditioning circuit, consequently worsening the efficiency of the entire system.
It is also well known that the refrigerant circuit operates at higher pressures than those of the conditioning circuit.
Therefore, there is the possibility that high pressure refrigerant leaks (even in the order of some tens of bars) may generate pressure peaks which, propagating along the conditioning circuit, may damage pipes and/or components (e.g., the secondary side of the exchanger, circulation pump, radiators/radiant panels, etc.), generally tried and tested to work at maximum pressures of 3 bars.
Furthermore, in case of leaks, the check valve (or similar non-return devices), preventing the flow of refrigerant through the same valve, does not allow it to expand in the conditioning circuit, preventing an effective and quick "absorption" of the above-mentioned pressure peaks; this may increase the risk of breakages and/or malfunctions.
The object of the present invention is to obviate such type of inconveniences by providing a low environmental impact heat pump system for room heating/cooling functions and/or for the production of domestic water comprising at least one highly efficient device capable of preventing possible refrigerant leaks from spreading internally to the installation and/or usage environment.
A further object of the present invention, at least for one executive variant thereof, is to provide a low environmental impact heat pump system for room heating/cooling functions and/or for the production of domestic water in which said at least one device adapted to intercept and block said possible refrigerant leaks also acts as a compensation element of the pressure peaks resulting from said refrigerant leaks.
A further object of the present invention, at least for one of the executive variants thereof, is to provide a low environmental impact heat pump system for room heating/cooling functions and/or for the production of domestic water in which said at least one device adapted to intercept and block said possible refrigerant leaks introduces a substantially negligible resistance to the flow of technical fluid of the same heat pump system, i.e. low or limited load losses.
A further object of the present invention, at least for one executive variant thereof, is to provide a low environmental impact heat pump system for room heating/cooling functions and/or for the production of domestic water without check valves.
These and other objects, which shall appear clear hereinafter, are achieved with a heat pump system according to the independent claims.
Other objects may also be achieved by means of the additional features of the dependent claims.
Further features of the present invention shall be better highlighted by the following description of a preferred embodiment, in accordance with the patent claims and illustrated, purely by way of a non-limiting example, in the annexed drawing tables, in which:

Fig. 1 schematically shows a heat pump system for room heating/cooling functions and/or for the production of domestic water according to the invention;
Figures 2a and 2b schematically show a detail of the heat pump system of Fig. 1, in accordance with a first and second operating configuration.

The features of at least one preferred variant of the heat pump system for room heating/cooling functions and/or for the production of domestic water of the invention are now described, making use of the references contained in the figures.
Reference numeral 1 therefore indicates, as a whole, the heat pump system of the invention that may be used for a domestic or non-domestic environment (e.g. commercial or industrial) heating and/or cooling functions and/or for the production of domestic water, for example domestic hot water.
As already partially said, a first circuit 2 is shown of the heat pump system 1, in which a refrigerant fluid which is evaporated at low pressure circulates, brought to high pressure, condensed and finally brought back to an evaporation pressure, and a second circuit 3 crossed by a technical fluid, preferably technical water, that may be used for room heating/cooling and/or for the production of domestic water.
Hereinafter, for descriptive simplicity, said first and second circuit of the heat pump system 1 of the invention shall be respectively referred to as "refrigeration circuit 2" and "conditioning circuit 3", where, as already mentioned, "conditioning" is indifferently to be referred to as both the cooling/heating function of an environment, and that for domestic water heating.
During the present description, refrigerant fluid shall be referred to as, without any limiting intent, a low environmental impact refrigerant (e.g., having a low GWP - Global Warming Potential) which, as mentioned, presents a greater flammability risk, such as, for example, the well-known R290 (Propane), R32 (Difluoromethane), or similar/the like.
As shown in Fig. 1, the refrigeration circuit 2 comprises, connected to each other via special pipes:

at least one first heat exchanger 20,
at least one second heat exchanger 21,
at least one compressor 22 positioned between said first and second heat exchanger 20, 21 and arranged to compress said refrigerant fluid between a minimum pressure and maximum pressure thereof,
at least one lamination valve 23 that achieves an expansion, at a substantially constant enthalpy, and cooling of the refrigerant fluid.

Said refrigeration circuit 2 may be switched, by means of a switching valve (not shown), e.g. "4 ways" between "cooling" and "heating" operating mode (and vice versa) with said first and second heat exchanger that may therefore operate, if necessary, either as a condenser or as an evaporator.
When in "heating" mode, the refrigerant fluid dissipates heat, by condensing, in the second exchanger 21 which therefore acts as a condenser, while absorbing heat, evaporating, in the first exchanger 20 which acts as an evaporator.
On the contrary, in "cooling" mode, the above-mentioned first heat exchanger 20 operates as a condenser of the refrigeration circuit 2, the second exchanger 21 as a relative evaporator.
More generally, the second heat exchanger 21 is preferably that in which the heat exchange takes place between the refrigerant fluid of the refrigeration circuit 2 and the technical fluid of the conditioning circuit 3.
For clarity of explanation, said second heat exchanger 21 shall be referred to as "main heat exchanger" or, more simply, "main exchanger".
If necessary, said main heat exchanger 21 may therefore operate:

as an evaporator and in such case the refrigerant fluid absorbs, at substantially constant pressure, thermal energy from the technical fluid, by cooling it, or
as a condenser and in such case the refrigerant fluid yields, at substantially constant pressure, part of the thermal energy thereof to the technical fluid, by heating it.

Therefore, it may be possible to identify, of said main heat exchanger 21, a primary side 24 at which the refrigerant fluid circulates and operates, and a secondary side 25, at which the technical fluid of the conditioning circuit 3 circulates and operates.
As anticipated, the conditioning circuit 3 may comprise at least one circulation pump 30 of the technical fluid and one or more terminals 31 for room heating/cooling and/or for the domestic water.
Said terminals 31 may therefore operate:

as heat dissipation devices and/or as conditioning units in heating/cooling modes, in such case comprising, for example, one or more radiators, floor or wall radiant panels, fan coils, convectors or similar devices, and/or
as heat accumulators containing the fluid circulating in the conditioning circuit 3, for example as buffers, and/or
as heat accumulators, for example as hot water storages (or the like) in case of domestic water heating.

Without any limiting intent and considering the operating direction F of the technical fluid as a reference, the circulation pump 30 may be placed upstream of the secondary side 25 of the main heat exchanger 21 (see Fig. 1).
As noted many times, the heat pump system 1 of the invention is preferably arranged to operate with low environmental impact refrigerant fluids (e.g. the well-known R32, propane R290 or the like) which, as seen, however, have the disadvantage of being flammable in contact with particularly hot components or elements or potentially able to produce sparks.
Also for this reason, the conditioning circuit 3 may further comprise at least one relief valve 43 capable of opening for pressures of the technical fluid generally greater than 3 bars, allowing a discharge thereof, for example, into the atmosphere; such condition may occur in presence of considerable refrigerant leaks from the refrigeration circuit 2.
A possible ventilation valve 44 (also known as "jolly" or "deaeration" valve), of manual or automatic type, also allows for the expulsion of small refrigerant leaks coming from the refrigeration circuit 2 besides the air possibly present in the pipes and/or in the terminals 31 of said conditioning circuit 3.
According to a possible executive embodiment of the invention and without any limiting intent, said relief valve 43 and/or said ventilation valve 44 may be part of a degasser device 4, suitably arranged to stop the flow of technical fluid and/or prevent said possible losses of refrigerant fluid, mainly resulting from defects and/or breakages of one or more components or pipes of the refrigeration circuit 2 (e.g., of the main heat exchanger 21), from reaching the heating circuit 3, the relevant terminals 31 and therefore spreading into the domestic (or commercial/industrial) environment, with harmful and dangerous effects for the users.
It is not necessary to dwell too much on the description of the technical and functional features of said degasser device 4 as it is a component per se already known to a person skilled in the art, widely used and available in a wide variety of models and construction variants.
In such context it is therefore sufficient to specify that considering once again the operating direction F of the technical fluid as a reference, said degasser device 4 is placed in the conditioning circuit 3 preferably downstream of the secondary side 25 of the main heat exchanger 21.
Said degasser device 4 may therefore comprise:

one inlet 40 connected to said secondary side 25 of the main heat exchanger 21,
one outlet 41 connected to the delivery pipe 32 for the terminals 31 of the conditioning circuit 3,
one expansion chamber 42 in which the refrigerant leaks are intercepted and/or separated from the technical fluid through a sudden slowing down thereof and the possible use of separation means such as mesh filters, perforated screens, turbulators or the like (not shown), said expansion chamber 42 being in fluid communication with:

said inlet 40 and outlet 41,
said at least one relief valve 43 and/or ventilation valve 44 adapted, as seen, to discharge outside at least said refrigerant fluid leaks intercepted and/or separated from the technical fluid.

Without any limiting intent, said degasser device 4 may also be of the type comprising a shutter body (not explicitly shown), inside the expansion chamber 42, for example a "floating" shutter, capable, in the known ways, of:

opening, or keeping open, the outlet 41 in conditions of regular operation of the heat pump system 1, thus allowing the normal flow and passage of the technical fluid from the main heat exchanger 21 to the terminals 31 of the conditioning circuit 3,
closing the outlet 41 in case of refrigerant leaks, in particular for quantities exceeding a predefined threshold considered as tolerable or non-dangerous, allowing the separation thereof from the technical fluid and preventing them from reaching said terminals 31 and spreading into the domestic (or commercial/industrial) environment.

According to the invention, it is also desired to prevent said possible refrigerant fluid leaks from reaching the terminals 31 of the conditioning circuit 3, by "ways" different from those prevented from the activation of the degasser device 4.
More precisely, it is desired to prevent a flow of refrigerant leaks (hereinafter referred to as "retrograde flow or reflux FR"; see Fig. 2a-2b) in opposite direction to that of operation of the technical fluid, i.e. towards the circulation pump 30 and the return branch 33 of the same conditioning circuit 3.
This may be achieved without the need to provide the known check valves normally used to close in presence of "parasitic circulations CP" in the conditioning circuit 3 of the technical fluid of the heat pump system 1 (i.e. in contrast with the direction imparted to the fluid by the circulation pump 30; see, for clarity, the arrow CP in Fig. 1 and/or 2a-2b).
In other words, according to the invention, said known check valve is replaced by a safety valve 5, schematically shown in the annexed figures, and capable of:

"letting" itself be crossed by the technical fluid (e.g. technical water) both when circulating in operating direction F and in opposite direction, i.e. in case, as seen, of parasitic circulations CP (which are therefore deliberately tolerated), but
closing in case of retrograde flows FR of possible refrigerant leaks coming from the main heat exchanger 21, so as to block the spreading thereof towards the return branch 33 of the conditioning circuit 3 and the relevant terminals 31.

As shown in Fig. 1, by way of an example, said safety valve 5 may be preferably placed, considering the operating direction F of the technical fluid in the conditioning circuit 3, upstream of the secondary side 25 of the main heat exchanger 21.
Preferably, said safety valve 5 may be placed between the outlet of the circulation pump 30 of said conditioning circuit 3 and the inlet of said secondary side 25 of the main heat exchanger 21.
According to a possible executive embodiment, which is among the preferred ones, said safety valve 5 may comprise:

a container body 50 (e.g. cylindrical or box-shaped) equipped with at least one first 51 and second 52 opening for the passage of at least the technical fluid of the conditioning circuit 3, said openings 51, 52 being able to consist of holes, slots or the like, and
at least one shutter 53 capable of shifting, substantially vertically, inside the container body 50 and acting as a "plug" for at least one of said passage openings 51, 52.

According to the example of Fig. 1, the first opening 51 of said container body 50 of the safety valve 5 is in fluid communication with the delivery of the circulation pump 30, while the second opening 52 is connected, for example via pipe sections, to the secondary side 25 of the main heat exchanger 21.
Without any limiting intent, according to a possible executive embodiment of the invention, said first and second opening 51, 52 may be two opposite passage openings, a lower one 51 and an upper 52 one, i.e. located, respectively, on the bottom 55 of the container body 50 of the safety valve 5 and on the relative top wall 56 thereof.
Preferably, the shutter 53 is capable of closing the lower opening 51 of the safety valve 5 exclusively in case of retrograde refrigerant flows FR, leaving it open instead in case of passage of the technical fluid, both in the operating direction F and in that opposite of the parasitic circulations CP.
In other words, as shall be seen in detail below, said safety valve 5 acts as a stop valve for the refrigerant fluid directed, in case of leaks, towards the return branch 33 of the conditioning circuit 3 and the relevant terminals 31, but not for the technical fluid which is therefore free to pass therethrough.
For such purpose, the shutter 53 of the safety valve 5 may comprise a floating body having a lower density than that of the technical fluid; in this way, when technical fluid is present in the safety valve 5, the shutter 53 floats inside the relevant container body 50, leaving the lower opening 51 thereof open (or opening it).
The safety valve 5 may also comprise at least one stop or end-of-stroke device 54 (hereinafter simply referred to as "end-of stroke 54") which allows the shutter 53 to float in the technical fluid without ever obstructing the upper opening 52, ensuring at the same time, large passage sections and consequent low load losses.
Without any limiting intent, said end-of-stroke 54 may for example comprise a plate 54 suitably sized and housed inside the container body 50 of the safety valve 5 and adapted to act as an upper block element for the floating of the shutter 53.
Naturally, nothing prevents the possibility of providing alternative and/or equivalent systems (variants not shown).
For example, it is possible to adequately shape and size the shutter 53 to remain always sufficiently distanced from the upper opening 52 of the safety valve 5 and, at the same time, allow for the flow of at least the technical fluid. For example, at least two protrusions projecting from the upper face of the shutter 53 may be provided to act as abutment elements on the top wall 56 of the container body 50 of the safety valve 5 and defining radial passages therebetween for at least said technical fluid.
Alternatively, it is possible to make the above-mentioned upper opening 52 on one side of the container body 50 of the safety valve 5, rather than in the top wall 56 thereof, as seen so far.
The density of said shutter 53 is instead greater than that of the refrigerant fluid. Therefore, when as a result of the above-mentioned leaks the safety valve 5 is completely filled with refrigerant, which has progressively replaced and substituted the technical fluid, the shutter 53 is no longer able to float, moving, also thanks to the contribution of the weight - force thereof, automatically and spontaneously on the bottom 55 of the container body 50, blocking the lower opening 51 thereof.
In such way, as anticipated, the possible retrograde flow FR of the refrigerant fluid stops, avoiding an unwanted and dangerous spreading thereof towards the conditioning circuit 3, particularly towards the return branch 33.
For further clarity, the operation of said safety valve 5 of the heat pump system 1 of the invention is described below.
When the heat pump system 1 of the invention operates in standard and/or optimal conditions (i.e. in the absence of leaks and/or malfunctions), the safety valve 5 is affected by the operating flow F of the technical fluid, which passes undisturbed therethrough and with negligible load losses; in fact, the internal volume of the container body 50 and the appropriately chosen dimensions and shape of the relative shutter 53, offer a substantially negligible resistance to the flow of technical fluid, in any case significantly lower than that of a non-return valve or similar devices.
In such conditions, the shutter 53 of the safety valve 5 is floating and raised from the bottom 55 of the container body 50; i.e., it is placed in substantial proximity to the end-of stroke position thereof, for example in contact with the end-of-stroke device 54, thus leaving both the lower 51 and upper 52 passage openings open and free.
In case of malfunction or breakage of one or more components of the refrigeration circuit 2 (e.g. of the main heat exchanger 21), a considerable quantity of refrigerant, characterised by pressures higher than those of the technical fluid, may penetrate and enter the conditioning circuit 3 and reach, with a retrograde flow FR, the safety valve 5.
At this point, the high pressure refrigerant leaks begin to "press" and "push" the technical fluid out of the container body 50 through the lower opening 51 of the safety valve 5 which remains substantially open thanks to the floating of the shutter 53 imparted by the residual technical fluid.
However, due to the progressive emptying of said technical fluid, replaced by the refrigerant fluid, the floating shutter 53 will begin to shift internally to the container body 50, move away from the above-mentioned end-of-stroke position (i.e. from the end-of-stroke device 54) and approach the lower opening 51 of the safety valve 5.
When all the technical fluid will be completely expelled from the container body 50 of the safety valve 5 and totally replaced by the refrigerant, the shutter 53, not being able to float any longer, will rest on the bottom 55 of the same container body 50, closing hermetically the passage 51 towards the conditioning circuit 3, as a result of the high pressures of the same refrigerant.
It therefore appears clear that the safety valve 5 of the heat pump system 1 of the invention does not prevent, in any way, possible parasitic circulations CP of the technical fluid (as instead happens with the traditional non-return valves), effectively stopping, only retrograde flows FR of the refrigerant in case of leaks and escapes from the refrigeration circuit 2.
In other words, said safety valve 5 is inserted in the heat pump system 1 of the invention with the sole intention of stopping possible retrograde flows FR of refrigerant towards the conditioning circuit 3, without any interest and purpose of also blocking the possible parasitic circulations CP of the technical fluid (e.g. of the technical water), which are therefore substantially tolerated.
The use of a safety valve 5, as described, may also lead to a second order of advantages and increased efficiency and operational life of the heat pump system 1 of the invention.
In fact, several times it has been said that the refrigerant fluid operates at high pressures (even in the order of a few tens of bars) and that, in case of leaks, it may generate pressure peaks which, propagating along the conditioning circuit 3, may generate damage to the relevant pipes and/or components, generally tested to work at lower pressures (usually equal to 3 bars).
The container body 50, acting as an expansion volume for the refrigerant, additional to that normally offered by the conditioning circuit 3, therefore allows said pressure peaks to be lowered and compensated more quickly, reducing potential damage to components such as the main heat exchanger 21, the degasser device 4 (in particular, the joints or fittings thereof connecting to the pipes of the conditioning circuit 3), the circulation pump 30, etc.
Finally, it should be noted that several variants of the heat pump system of the invention are possible for the man skilled in the art, without departing from the novelty scopes of the inventive idea, as well as it is clear that in the practical embodiment of the invention the various components described above may be replaced with technically equivalent elements.
For example, as an alternative to what has been said so far, nothing prevents said relief 43 and/or ventilation 44 valves of the conditioning circuit 3, instead of being part of the degasser device 4, from being integrated directly into the safety valve 5 of the invention, for example installed and in fluid communication with the container body 50 thereof.
It is also possible to provide that said relief 43 and/or ventilation 44 valves may be simultaneously provided both in the degasser device 4 and in the safety valve 5, so as to guarantee increased safety and efficiency of the heat pump system 1 of the invention.
In conclusion, it appears clear that with the safety valve 5 of the heat pump system 1 of the invention the pre-set objectives are achieved, in particular the possibility of eliminating, or in any case effectively limiting, the risk that possible refrigerant leaks, spreading through the conditioning circuit 3, may reach the installation and/or usage environment of said heat pump system 1, endangering the safety of the users and/or the integrity of the relevant building structures in case of formation of flammable and/or explosive concentrations. Furthermore, the safety valve 5 of the invention offers, as seen, a substantially negligible resistance to the flow of the technical fluid of the conditioning circuit 3 and, therefore, pressure losses significantly lower than those typical of a non-return valve or similar devices.

Claims

Heat pump system (1) comprising at least:
- one refrigeration circuit (2) wherein a refrigerant fluid circulates and operates at the primary side (24) of a main heat exchanger (21),

- one conditioning circuit (3) wherein a technical fluid, used for room heating/cooling functions and/or for the production of domestic water, circulates and operates at the secondary side (25) of said same main heat exchanger (21),
wherein:
- the heat exchange between said refrigerant fluid and technical fluid is carried out in said main heat exchanger (21),

- said conditioning circuit (3) comprises at least one circulation pump (30) for said technical fluid and one or more terminals (31) for room heating/cooling and/or for the production of domestic water,
characterised in that said conditioning circuit (3) further comprises a safety valve (5) capable of:
- being crossed by said technical fluid both when circulating in operating direction (F) and in case of parasitic circulations (CP) thereof in said conditioning circuit (3),

- closing in case of flows of refrigerant fluid leaks in said conditioning circuit (3) in opposite direction (FR) to the operating one (F) of said technical fluid,
said safety valve (5) therefore acting as a stop valve for said refrigerant fluid but not for said technical fluid.
Heat pump system (1) according to claim 1, characterised in that said safety valve (5) is located, with reference to the operating direction (F) of said technical fluid, upstream of said secondary side (25) of said main heat exchanger (21; 20).
Heat pump system (1) according to claim 2, characterised in that said safety valve (5) is located between the outlet of said circulation pump (30), placed upstream of said main heat exchanger (21), and the inlet of said secondary side (25) of said main heat exchanger (21).
Heat pump system (1) according to one or more of the previous claims, characterised in that said safety valve (5) comprises at least:
- a container body (50) equipped with at least one first (51) and second (52) passage opening for at least said technical fluid of the conditioning circuit (3), and

- at least one shutter (53) capable of shifting inside the container body (50) to act as a "plug" for at least one of said passage openings (51, 52).
Heat pump system (1) according to the previous claim, characterised in that said shutter (53) is a floating body (53) having a lower density than that of said technical fluid but greater than that of said refrigerant fluid, said shutter (53) being capable of:
- floating inside said container body (50) of said safety valve (5) in presence of technical fluid, in such case said first (51) and second opening (52) being both always open,

- occluding said first opening (51) of said container body (50) of said safety valve (5) when totally full of said possible refrigerant leaks, said shutter (53) blocking and/or stopping the spreading of said refrigerant in/towards the return branch (33) of said conditioning circuit (3).
Heat pump system (1) according to claim 5, characterised in that said safety valve (5) internally comprises an end-of-stroke device (54) for said floating shutter (53), said end-of-stroke device (54) enabling said shutter (53) to float in the container body (50) of said safety valve (5) without ever obstructing the second opening (52) thereof.
Heat pump system (1) according to one or more of the previous claims 4 to 6, characterised in that said first (51) and second (52) opening are two opposite passage openings, a lower one (51) and an upper (52) one, located, respectively, on the bottom (55) of the container body (50) of said safety valve (5) and on the relative top wall (56) thereof.
Heat pump system (1) according to one or more of the previous claims, characterised in that said container body (50) of said safety valve (5) also acts as a supplementary expansion volume for said possible refrigerant leaks.
Heat pump system (1) according to one or more of the previous claims, characterised in that said conditioning circuit (3) further comprises a relief valve (43).
Heat pump system (1) according to one or more of the previous claims, characterised in that said conditioning circuit (3) further comprises a ventilation valve (44).
Heat pump system (1) according to claim 8 and/or 9, characterised in that said relief valve (43) and/or said ventilation valve (44) are integrated to said safety valve (5) and in fluid communication with the container body (50) thereof.
Heat pump system (1) according to claim 8 and/or 9, characterised in that said relief valve (43) and/or said ventilation valve (44) are part of a degasser device (4) of said conditioning circuit (3).
Heat pump system (1) according to claim 8, characterised in that said degasser device (4) is located, with reference to the operating direction (F) of said technical fluid, downstream of said secondary side (25) of the main heat exchanger (21),
Heat pump system (1) according to the previous claim, characterised in that said degasser device (4) further comprises at least: one inlet (40) connected to said secondary side (25) of said main exchanger (21), one outlet (41) connected to a delivery pipe (32) of said terminals (31) of the conditioning circuit (3), one expansion chamber (42) in which said refrigerant leaks are intercepted and/or separated from said technical fluid.
Heat pump system (1) according to one or more of claims 12 to 14, characterised in that said degasser device (4) is of the "float" type.
Heat pump system (1) according to any previous claim, characterised in that said refrigerant fluid of the refrigeration circuit (2) is a low environmental impact refrigerant, for example propane R290, difluoromethane R32 or the like/similar.