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Title:
HEAT PUMP
Document Type and Number:
WIPO Patent Application WO/2017/072643
Kind Code:
A1
Abstract:
The heat pump (1) comprises: a first unit (2) which comprises: - a first fluid- operated circuit (3), suitable for the circulation within the same of a first fluid of the refrigerant type; - a second fluid- operated circuit (4), suitable for the circulation within the same of a second fluid of the aeriform type; - first heat exchange means (13, 15, 17) between the first fluid- operated circuit (3) and the second fluid- operated circuit (4); a second unit (6) which comprises: - a third fluid- operated circuit (7) connected to the first fluid- operated circuit (3); - a fourth fluid- operated circuit (8), suitable for the circulation within the same of a third fluid; - second heat exchange means (11) between the third fluid- operated circuit (7) and the fourth fluid- operated circuit (8); wherein the first heat exchange means (13, 15, 17) comprise: a first heat exchange member (13); a second heat exchange member (15) connected in a fluid- operated manner to the first heat exchange member (13); a fan (17) for the movement of the second fluid interposed in a sandwich¬ like manner between the first heat exchange member (13) and the second heat exchange member (15).

Inventors:
CONTI, Francesco (Via Franzoni 67, 6604 Locarno, 6604, CH)
Application Number:
IB2016/056366
Publication Date:
May 04, 2017
Filing Date:
October 24, 2016
Export Citation:
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Assignee:
INNOVIDA SWISS TECHNOLOGY S.A. (Via San Gottardo, 18B, 6532 Arbedo-Castione, 6532, CH)
International Classes:
F24F3/00; F24F1/06
Domestic Patent References:
WO2013138695A12013-09-19
Foreign References:
CN104501317A2015-04-08
DE2417082A11975-10-16
CN104566682A2015-04-29
Attorney, Agent or Firm:
BRUNACCI, Marco (BRUNACCI & PARTNERS S.r.l, Via Scaglia Est 19-31, Modena, 41126, IT)
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Claims:
CLAIMS

1) Heat pump (1), particularly for the heating and/or cooling of fluids, comprising:

at least a first unit (2) which comprises:

- at least a first fluid- operated circuit (3), suitable for the circulation within the same of at least a first fluid of the refrigerant type;

- at least a second fluid- operated circuit (4), suitable for the circulation within the same of at least a second fluid of the aeriform type;

- first heat exchange means (13, 15, 17) between said first fluid- operated circuit (3) and said second fluid- operated circuit (4);

at least a second unit (6) which comprises:

- at least a third fluid- operated circuit (7), suitable for the circulation of said first fluid and connected to said first fluid- operated circuit (3);

- at least a fourth fluid- operated circuit (8), suitable for the circulation within the same of at least a third fluid;

- compressor means (10), suitable for the suction and compression of said first fluid coming from said first heat exchange means (13, 15, 17); and

- second heat exchange means (11) between said third fluid- operated circuit (7) and said fourth fluid- operated circuit (8);

characterized in that said first heat exchange means (13, 15, 17) comprise:

at least a first heat exchange member (13), in which said first fluid circulates, substantially plate-shaped and lying on a first plane (12);

at least a second heat exchange member (15) in which said first fluid circulates, connected in a fluid- operated manner to said first heat exchange member (13), substantially plate-shaped and lying on a second plane (14) substantially parallel to said first plane (12);

at least one fan (17) for the movement of said second fluid, rotatable around an axis of rotation (A) substantially perpendicular to said first plane (12) and to said second plane (14), lying on a third plane (16) substantially parallel to said first plane (12) and to said second plane (14) and interposed in a sandwich-like manner between said first heat exchange member (13) and said second heat exchange member (15). 2) Heat pump (1) according to claim 1, characterized in that said first plane (12), said second plane (14) and said third plane (16) are substantially vertical and said axis of rotation (A) is substantially horizontal.

3) Heat pump (1) according to one or more of the preceding claims, characterized in that said first unit (2) comprises at least a first container body

(19) having at least a cover (20), said fan (17) being connected and supported by said cover (20).

4) Heat pump (1) according to one or more of the preceding claims, characterized in that said first heat exchange means (13, 15, 17) comprise at least an electric motor (18) operatively connected to said fan (17) for the rotation of the fan (17) itself around said axis of rotation (A), said electric motor (18) being arranged in the space between said first plane (12) and said third plane (16).

5) Heat pump (1) according to one or more of the preceding claims, characterized in that said first unit (2) comprises at least one expansion valve element (23) arranged along said first fluid- operated circuit (3) upstream of said first heat exchange means (13, 15, 17) and able to expand said first fluid.

6) Heat pump (1) according to one or more of the preceding claims, characterized in that said first unit (2) comprises at least one bypass valve element (24) arranged in parallel to said expansion valve element (23).

7) Heat pump (1) according to one or more of the preceding claims, characterized in that said second unit (6) comprises at least a second container body (26) comprising a plurality of walls having respective inner and outer faces, said inner faces being covered with at least one layer in a sound absorbing material.

8) Heat pump (1) according to one or more of the preceding claims, characterized in that said second unit (6) comprises:

at least a fifth fluid- operated circuit (28, 29), suitable for the circulation within the same of a fourth fluid; and

- third heat exchange means (27), suitable for the heat exchange between said fourth fluid- operated circuit (8) and said fifth fluid- operated circuit (28, 29).

9) Heat pump (1) according to one or more of the preceding claims, characterized in that said second unit (6) comprises recovery means (30a, 30b) of the heat dissipated by said compressor means (10), said recovery means (30a, 30b) being connected to said fourth fluid- operated circuit (8).

10) Heat pump (1) according to one or more of the preceding claims, characterized in that said second unit (6) comprises pumping means (9) of said third fluid within said fourth fluid- operated circuit (8).

11) Heat pump (1) according to one or more of the preceding claims, characterized in that said second unit (6) comprises at least one command unit (31) suitable for the control of the operation of said first unit (2) and of said second unit (6).

12) Heat pump (1) according to one or more of the preceding claims, characterized in that said command unit (31) comprises at least one limiting device for the startup inrush current of said compressor means (10).

13) Heat pump (1) according to one or more of the preceding claims, characterized in that said first unit (2) comprises at least one of:

a first temperature sensor (34) of said first fluid arranged along said first fluid- operated circuit (3) between said first heat exchange means (13, 15, 17) and said expansion valve element (23); and

a second temperature sensor (35) of said second fluid arranged in the proximity of said fan (17).

14) Heat pump (1) according to one or more of the preceding claims, characterized in that said second unit (6) comprises at least one of:

a third temperature sensor (36) of said fourth fluid entering said third heat exchange means (27);

- a fourth temperature sensor (37) of said fourth fluid exiting said third heat exchange means (27).

Description:
HEAT PUMP

Technical Field

The present invention relates to a heat pump for the heating and/or cooling of fluids.

Background Art

In the field of heating and/or cooling fluids such as air and water, the use of thermal machines such as heat pumps and the like is known.

Heat pumps are generally composed of a closed fluid-operated circuit, along which a refrigerant fluid circulates in a thermodynamic cycle and, therefore, following variations in pressure and/or temperature, is transformed from a liquid state to a gaseous state and vice versa.

These machines comprise first heat exchange means in which the refrigerant fluid flows and which are placed in contact with a first service fluid which, generally, is composed of air, water or other liquid or aeriform fluids.

In particular, the first heat exchange means are composed of an evaporator in which the refrigerant fluid absorbs heat from the first service fluid and evaporates at low pressure.

In the event of the first service fluid consisting of air, a movement element for the first service fluid is present consisting of a fan which allows suctioning the air from the surrounding environment and conveying it at the first heat exchange means.

In its gaseous state, the refrigerant fluid coming from the first heat exchange means is suctioned and compressed by means of compressor means.

During compression, the refrigerant fluid absorbs a certain amount of heat and is overheated.

Leaving the compressor means, the refrigerant fluid, which is still in the gaseous state, is conveyed to the second heat exchange means composed of a condenser in which the fluid itself condenses at high pressure passing from the gaseous state to the liquid state.

During this transition of state, the refrigerant fluid transfers heat to a second service fluid, which may be air, water or other liquid or aeriform fluids. The machine also comprises an expansion valve in which, coming from the second heat exchange means, the refrigerant fluid undergoes a reduction in pressure and the refrigerant fluid itself passes to a state in which both the liquid phase and the gaseous phase are present.

In the event of the heat pumps being used for heating the second service fluid (water or air), the first service fluid is defined as the cold source, from which the refrigerant fluid absorbs heat, while the second service fluid is defined as the hot source, to which the refrigerant fluid transfers heat.

Vice versa, when the heat pumps are used for the refrigeration of the second service fluid (generally air), the second service fluid is defined as the cold source, from which the refrigerant fluid absorbs heat, while the first service fluid is defined as the hot source, to which the refrigerant fluid transfers heat. These heat pumps are at times intended to heat and/or cool the water in public and/or private swimming pools, thus making their use more pleasant, for example by cooling them during the summer and heating them during the winter.

Within this field of use, a first type of mono-bloc thermal machines is known in which all the components of the machine are grouped in the same unit located in specific containment premises inside which the piping dedicated to the passage of the continuous flow of water leaving and returning to the swimming pool are also present.

The heat exchange takes place in the containment premises between the second heat exchange means and the piping arranged near to these.

This first type of thermal machines of a known type has the main drawback of requiring the presence of channelling means of the first service fluid in the proximity of the thermal machine, inside the containment premises.

A second type of mono-bloc thermal machines is known, located outside the containment premises, in the proximity of the first service fluid.

In this case the thermal machine requires special fluid- operated connections with the water in the swimming pool.

The main drawback of this second type of thermal machines is that of offering less energy efficiency with equal consumption for heating the water in the swimming pool, above all in the winter months in which the air temperature is particularly low and the evaporation operations of the refrigerant fluid are longer and more difficult due to the dispersion of heat due to the length of the fluid- operated connections.

Another drawback of this second type of thermal machines of the known type is due to noise pollution, generated by the rotation and vibrations of the fan, which spread into the surrounding environment.

Another drawback is linked to the risk of injury to persons who may accidentally come into contact with the fan which, being positioned outside, is easily accessible also to inexperienced persons.

A third type of thermal machines is known, called "split", which comprise two units connected together by means of at least two tubular elements for the transit of the refrigerant fluid between a first unit, located outside the containment premises, and a second unit, located inside these premises.

Generally, the first unit comprises first heat exchange means for the passage of the refrigerant fluid from the liquid to the gaseous state and the second unit comprises second heat exchange means through which the water contained in the swimming pool is heated.

The flow of water to be heated coming from the swimming pool is channelled through special tubular elements placed in the proximity of the second heat exchange means to exchange the heat between them and, once this heat exchange has taken place, the flow of water continues and returns to the swimming pool.

The third type of thermal machines of known type also has some drawbacks. The first unit is in fact usually composed of one or more very bulky fans, which stand next to, on one side, the radiator in which the refrigerant fluid circulates and, to guarantee an appropriate heat exchange, the first unit is rather large in size and implies many limits for freedom of installation.

In addition to this, the positioning outdoors of the first unit makes the evaporation operations of the refrigerant fluid longer during the winter months when the air temperature is particularly low, leading to energy dissipation and high consumption. This dissipation leads to high energy consumption, increasing the cost burden for the clients with, however, the risk of machine the machine less interesting to clients.

Moreover, the distance between the first unit and the second unit requires the presence of tubular elements connecting the two units, the energy dissipation depending on the length of these tubular elements.

Another drawback is given by the noise pollution due to the operation of the thermal machine, because, with the first unit exposed to the outdoor environment, the noise and vibrations generated by the movement of the fan is particularly perceivable in the areas surrounding the thermal machine.

Another drawback is linked to the movement of the fan which, being easily accessible from the outside, places the safety of persons who may accidentally access it at risk.

Description of the Invention

The main aim of the present invention is to provide a heat pump with a small size in order to maximise its efficiency and reduce energy consumption and environmental impacts.

One object of the present invention is to provide a heat pump which allows reducing dissipation and the related demands for energy to make it operational. Another object of the present invention is to provide a heat pump which allows reducing noise pollution generated by the rotation of the fan to move the first service fluid and by the electric motors connected thereto to drive the fan.

Another object of the present invention is to provide a heat pump which allows maximising the energy supplied by the first service fluid, protecting the fan and the first heat exchange means from the atmospheric agents in the outside environment.

Another object of the present invention is to provide a heat pump which allows maximising personal safety by making the air movement means hard to reach by the persons themselves.

Another object of the present invention is to provide a heat pump which allows to overcome the mentioned drawbacks of the prior art within the ambit of a rational and effective to use solution. The above mentioned objects are achieved by the present heat pump for the heating and/or cooling of fluids having the characteristics of claim 1.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become better evident from the description of a preferred, but not exclusive, embodiment of a heat pump, illustrated by way of an indicative, but non-limiting example in the accompanying drawings in which:

Figure 1 is an axonometric view of the heat pump according to the invention; Figure 2 shows a diagram of operation of the heat pump according to the invention;

Figure 3 is a side view of the heat pump according to the invention;

Figure 4 is an axonometric view of a detail of the heat pump according to the invention.

Embodiments of the Invention

With particular reference to such illustrations, reference numeral 1 globally indicates a heat pump for the heating and/or cooling of fluids.

The heat pump 1 comprises a first unit 2 having:

a first fluid- operated circuit 3, suitable for the circulation within the same of a first fluid of the refrigerant type;

- a second fluid-operated circuit 4, suitable for the circulation within the same of a second fluid of the aeriform type;

first heat exchange means 13, 15, 17 between the first fluid- operated circuit 3 and the second fluid- operated circuit 4.

The heat pump 1 also comprises a second unit 6 having:

- a third fluid- operated circuit 7, suitable for the circulation of the first fluid and connected to the first fluid- operated circuit 3. More in detail, the two circuits are connected to each other, but in the first fluid- operated circuit 3, the first fluid flows in the gaseous state, while in the third fluid- operated circuit 7, the first fluid flows in the liquid state;

- a fourth fluid- operated circuit 8, suitable for the circulation within the same of a third fluid of the liquid type (e.g. water) by means of suitable pumping means 9 which facilitate the transit of the same in the proximity of the second heat exchange means 11 ;

compressor means 10, suitable for the suction and compression of the first fluid coming from the first heat exchange means 13, 15, 17;

second heat exchange means 11 between the third fluid- operated circuit 7 and the fourth fluid-operated circuit 8.

According to the invention, the first heat exchange means 13, 15, 17 comprise: a first heat exchange member 13, in which the first fluid circulates, substantially plate-shaped and lying on a first plane 12;

a second heat exchange member 15, in which the first fluid circulates, connected in a fluid- operated manner to the first heat exchange member 13, substantially plate-shaped and lying on a second plane 14 substantially parallel to the first plane 12;

one fan 17 for the movement of the second fluid, rotatable around an axis of rotation A substantially perpendicular to the first plane 12 and to the second plane 14, lying on a third plane 16 substantially parallel to the two planes 12 and 14 and interposed in a sandwich-like manner between the first heat exchange member 13 and the second heat exchange member 15.

Within the ambit of this discussion, the expression "substantially plate-shaped" does not mean, exclusively, that the first heat exchange member 13 and the second heat exchange member 15 are plate-shaped in form, but simply that the form of the first heat exchange member 13 and of the second heat exchange member 15 are extended further along two directions of the Cartesian plane parallel to the planes 12, 14, and to a lesser extent along the third direction of the Cartesian plane perpendicular to the planes 12, 14.

The expression "interposed in a sandwich-like manner" refers to the specific structure of the first heat exchange means 13, 15, 17, in which the first heat exchange member 13 and the second heat exchange member 15, being parallel and spaced apart from each other, define two external layers of a sandwich and the fan 17 is interposed within the space between the first heat exchange member 13 and the second heat exchange member 15.

Preferably, the first heat exchange member 13 is of the type of a substantially plate-shaped radiator with a rectangular or quadrangular outline. It cannot however be ruled out that the first heat exchange member 13 be constituted by a tubular element with a coil-type shape which extends along the first plane 12.

Similarly to the first heat exchange member 13, the second heat exchange member 15 is of the type of a substantially plate-shaped radiator with a rectangular or quadrangular outline.

It cannot however be ruled out that the second heat exchange member 15 be constituted by a tubular element with a coil-type shape which extends along the second plane 14.

The three planes 12, 14 and 16 are substantially vertical, while the axis of rotation A is substantially horizontal and extends perpendicularly to them.

The first heat exchange means 13, 15, 17 comprise an electric motor 18 operatively connected to the fan 17 for the rotation of the fan itself around the axis of rotation A.

More in detail, the electric motor 18 is arranged in the space between the second plane 14 and the third plane 16.

By means of the operation of the fan 17, the second fluid is moved in a vortex by the fan itself along the axis of rotation A and passes through the first heat exchange member 13 to reach the second heat exchange member 15.

Advantageously, in the passage between the first heat exchange member 13 and the second heat exchange member 15, the second fluid laps the electric motor 18 and promotes the recovery of the heat due to the relative overheating.

The first unit 2 comprises a first container body 19 having at least one cover 20. Conveniently, the fan 17 is connected and supported by the cover 20.

More in detail, the first container body 19 comprises a plurality of walls associated with each other to define a substantially U-like shape, inside which are accommodated the first heat exchange means 13, 15, 17.

The fan 17 is supported by the cover 20 by means of appropriate support brackets 21 with a first ending part fixed to the cover itself and a second ending part fixed to a housing body 22 of the fan 17.

The first unit 2 comprises at least one expansion valve element 23 arranged along the first fluid- operated circuit 3, upstream of the first heat exchange means 13, 15, 17 and adapted to expand the first fluid.

In the ambit of this discussion, the terms "upstream" and "downstream" are related to the operating cycle of the heat pump 1 for the heating of a fluid having a lower temperature than the temperature of another fluid.

Advantageously, the expansion valve element 23 is chosen from the group comprising thermostatic expansion valves or electronic expansion valves, but the use of other types of valve cannot be ruled out.

In particular, the expansion valve element 23 has a special throttle adapted to generate friction in the passage of the first fluid circulating through it, and more in particular, this friction promotes the complete transition from the gaseous state to the liquid state of the first fluid which, more in detail, has a substantially nebulised biphasic state.

Via the expansion valve element 23 the first fluid is injected into the first heat exchange member 13 and the second heat exchange member 15.

The first unit 2 comprises a bypass valve element 24 arranged in parallel to the expansion valve element 23.

More in detail, the bypass valve element 24 is of the type of a check valve adapted to defrost the first heat exchange member 13 and the second heat exchange member 15 through the inlet of a hot gas following the inversion of the refrigerating cycle, which is done with the use of a special 4-way valve 25. In particular, the 4-way valve 25 allows inverting the normal heating operating cycle of a fluid with respect to a cold source, in a cooling cycle of the fluid itself with respect to a hot source.

Even more specifically, when the heat pump 1 operates according to a cooling operating cycle, the 4-way valve 25 allows exchanging the physical state of the refrigerant fluid inside the first and second heat exchange member 13, 15 and of the second heat exchange means 11, with respect to the physical state that such refrigerant fluid would have in them during the heating operating cycle.

This exchange takes place by inverting the operating mode of the first heat exchange means 13, 15, 17 and of the second heat exchange means 11 with respect to the relative operating mode during the heating operating cycle.

The second unit 6 comprises at least a second container body 26, substantially rectangular, having a plurality of walls, each of which comprising an inner face and an outer face.

Advantageously, each of the inner faces is covered with a plurality of layers in a sound absorbing material so as to guarantee the noiselessness of the second unit itself.

The second unit 6 also comprises:

a fifth fluid- operated circuit 28, 29, suitable for the circulation within the same of a fourth fluid; and

third heat exchange means 27, suitable for the heat exchange between the fourth fluid- operated circuit 8 and the fifth fluid- operated circuit 28, 29.

The fourth fluid is of the type of swimming pool water including, e.g., chlorinated water, saline water or seawater.

The fifth fluid- operated circuit 28, 29 is composed of a first tubular element 28, along which the fourth fluid leaving the swimming pool flows, and of a second tubular element 29, along which the fourth fluid returning to the swimming pool flows.

The first tubular element 28 and the second tubular element 29 are connected e.g. to filtering means of the swimming pool water.

The third heat exchange means 27 allow maintaining the fourth fluid separate from the first fluid, as the exchange of heat between these is done by means of the third fluid.

In this way it is possible to prevent contamination between the refrigerant fluid and the swimming pool water, in the event of the breakage of the second heat exchange means 11.

Moreover, the third heat exchange means 27 are made from special material suited to resisting the corrosion of all possible types of water contained in the swimming pool.

Advantageously, the second unit 6 comprises recovery means 30a, 30b of the heat dissipated by the compressor means 10 during the compression of the first fluid.

More specifically, the recovery means 30a, 30b comprise:

a first recovery element 30a, with a coil shape wrapped around the casing of the compressor means 10 to recover the heat dissipated by the compressor means themselves during operation; and

a second recovery element 30b, positioned at the fourth fluid- operated circuit 8 and connected to the first recovery element 30a via a pipe in which a heat-conveying fluid flows, transferring the heat from the first recovery element 30b to the second recovery element 30b.

This solution allows the heat dissipated by the compressor means 10 to be transferred to the third fluid circulating in the fourth fluid- operated circuit 8.

The second unit 6 comprises a command unit 31 , suitable for the control of the operation of the first unit 2 and of the second unit 6.

Advantageously, the command unit 31 is contained inside the second unit 6 to prevent exposure to atmospheric agents and to ensure optimal operation.

Conveniently, the command unit 31 comprises a limiting device for the startup inrush current of the compressor means 10.

The inrush current limiting device is substantially a soft-starter system which electronically controls the ramp of the inrush current, in order to ensure the optimal operation of the compressor means 10.

The heat pump 1 comprises a first pressure transducer 32, positioned along the third fluid- operated circuit 7 upstream of the compressor means 10 and adapted to detect the pressure level of the first fluid leaving the first heat exchange means 13, 15, 17.

In addition, the heat pump 1 comprises a second pressure transducer 33, positioned along the third fluid- operated circuit 7 downstream of the compressor means 10.

The second pressure transducer 33 is adapted to detect the pressure level of the first fluid following the relative compression exerted by the compressor means 10.

Both pressure transducers 32 and 33 are operatively connected to the command unit 31, which stops the heat pump 1 in case of abnormal pressure being detected, and can be used for the continuous adjustment of any electronic expansion valve.

In addition to the pressure levels of the first fluid, the heat pump 1 also controls the temperature of the first, second and fourth fluid.

In particular, the first unit 2 comprises:

a first temperature sensor 34 of the first fluid, arranged along the first fluid- operated circuit 3 between the first heat exchange means 13, 15, 17 and the expansion valve element 23; and

a second temperature sensor 35 of the second fluid, arranged in the proximity of the fan 17.

The second unit 6 comprises:

a third temperature sensor 36 of the fourth fluid entering the third heat exchange means 27;

a fourth temperature sensor 37 of the fourth fluid exiting the third heat exchange means 27.

The temperature sensors 34, 35, 36 and 37 are operationally connected to the command unit 31 to process the acquired signals.

Conveniently, the command unit 31 manages the operation of the heat pump 1 via a suitable software implemented to perform the many automatic functions.

In particular, this software manages the exchanges of heat between the first fluid and the second fluid and between the third fluid and the fourth fluid and manages an automatic defrosting system which allows the heat pump 1 to operate correctly even in conditions of relatively low temperature of the second fluid.

The difference in temperature between the first fluid and the second fluid leads to the formation of rime at the first heat exchange member 13 and at the second heat exchange member 15 which causes a progressive obstruction of the passage of the second fluid.

The operation of the heat pump 1 is described below.

The first fluid circulates in the first fluid- operated circuit 3 positioned at the first heat exchange means 13, 15, 17 and, more specifically, in the first heat exchange member 13 and in the second heat exchange member 15.

By means of the operation of the fan 17, the second fluid is moved in a vortex by this along the axis of rotation A and passes through the first heat exchange member 13 to reach the second heat exchange member 15. In the passage between the first heat exchange member 13 and the second heat exchange member 15, the second fluid, lapping the electric motor 18, promotes the recovery of the heat due to the overheating of the electric motor itself in order to promote the transformation from liquid to gaseous state of the first fluid.

After the first fluid has passed from the liquid state to the gaseous state, the first fluid transfers from the first fluid- operated circuit 3 to the third fluid- operated circuit 7 and is suctioned by means of the compressor means 10 which send it to the second heat exchange means 11.

In the second heat exchange means 11 the first fluid, in gaseous state, transfers its own heat to the fourth intermediate fluid- operated circuit 8 in which water circulates, which is pumped in it by means of the pumping means 9 and, when the heat has been exchanged between the first fluid and the third fluid, the first fluid is transformed from gaseous to liquid state.

The fourth fluid- operated circuit 8 is in turn connected to the third heat exchange means 27 to transfer the heat acquired from the third fluid, circulating in the fourth fluid- operated circuit 8, to the flow of the fourth fluid leaving the swimming pool and circulating in the fifth fluid- operated circuit 28, 29.

After the heat has been exchanged between the fourth and the fifth fluid- operated circuit 8, 28, 29, the fourth fluid returns heated to the swimming pool. The first fluid, after having passed through the second heat exchange means 11, flows through the expansion valve element 23 which promotes the cooling and therefore the transition of the first fluid itself from the gaseous state to the liquid state which, more specifically, has a substantially nebulised biphasic state.

More specifically, the command unit 31, by means of the first temperature sensor 34, the second temperature sensor 35, the third temperature sensor 36 and the fourth temperature sensor 37, switches on the heat pump 1 when the temperature of the fourth fluid is below a minimum set value and switches off the heat pump 1 when the fourth fluid reaches the required temperature.

Moreover, if there is no automatic defrosting system, the command unit 31 cuts in to block the operation of the heat pump 1 when the temperature of the second fluid is detected and found to be below a given threshold. With the command unit 31 it is possible to set the optimal rotational speed of the fan 17 according to the noise it generates.

It has in practice been found that the described invention achieves the intended objects and, in particular, the fact is underlined that the heat pump designed in this way is small in size and offers a considerably high level of operational efficiency compared to the heat pumps of known type.

The particularly small size of the first unit leads to a reduction in environmental impact both if the first unit is placed inside a small lightwell, positioned outside or supported by a wall.

Moreover, the first heat exchange means designed in this way are able to reduce noise pollution generated by the rotation of the fan and to maximise energy efficiency by recovering the heat dissipated by the electric motor driving the fan itself.

The positioning of the fan between the two heat exchange members also ensures the safety of persons who cannot freely access the fan.