WO2016142760A1

WO2016142760A1 - Air conveyor for heat pump

Info

Publication number: WO2016142760A1
Application number: PCT/IB2016/000190
Authority: WO
Inventors: Paolo Canestrari; Francesco PERTICAROLI
Original assignee: Ariston Thermo S.P.A.
Priority date: 2015-03-06
Filing date: 2016-02-23
Publication date: 2016-09-15
Also published as: DE212016000060U1; EP3265727A1; ES1214854U; ES1214854Y

Abstract

The object of the present invention is an air-air or air-water heat pump (HP) where an air conveyor (104) is provided in order to direct the air constituting the heat source for the evaporator (102) towards its evaporator front (106). The invention provides means for improving the uniformity of the air distribution on the evaporator front (106). According to a preferred variant, flow guides (107) are provided that form the channels (108) ending substantially in contact with said evaporator front (106) with sections of outlet area Si such that in correspondence, the air flow density is substantially equal for each of said channels (108). The advantages of the invention consist in the fact that a uniform distribution of the air flow density improves the efficiency of the heat pump (HP).

Description

AIR CONVEYOR FOR HEAT PUMP

D E S C R I P T I O N

The object of the present invention are means for improving a heat exchanger between air and another means, where its air-side inlet front is flat.

In particular, such a heat exchanger is an exchanger of a heat pump.

Even more in particular, such a heat exchanger is the evaporator of an air-water or air-air heat pump where, therefore, the heat source is air that crosses an evaporator, provided with a conveyor for air to be sent to the evaporator and where, but only preferably, said heat pump, if it is of the air-water type:

is aimed at producing household hot water;

is for household use or for commercial activities;

- is intended to be installed in indoor environments, such as, generally, technical rooms, basements or utility rooms;

uses air as a heat source coming from a different environment from that of installation;

Without loss of generality, the following description will be in particular- referred to the above air-water heat pumps; nonetheless, what described is applicable to any air conduit where it is appropriate to straighten or to guide the air flow, for example before encountering a heat exchanger.

In such heat pumps, even if installed inside a building, air of the outside environment is almost always used as a cold source; a feeding conduit is therefore provided for sending air drawn from the exterior to the evaporator and an expulsion channelling outside the same air.

The conduits used in air-water heat pumps are normally with a circular section with an increasing diameter for increasing operating flow rates. Typically, for household applications the diameters commercially used are 100, 125, 150, 160, 200 mm and anyway suggested by the manufacturer. Rectangular sections are only used for low flow applications. The figures included in the description show circular conduits without minimising the generality of the invention.

The fact that the location of the heat pump is, wherever possible, a basement, implies that preferably the air inlet to the machine is made high, so as to be able to engage a conduit trunk descending vertically at least from the ground level, jointed with an elbow to a previous stretch of horizontal conduit connected to the air inlet on an outer wall of the building.

On the other hand, for constructional reasons, it is preferable that the evaporator of the heat pump is arranged with vertical setup, at least for an easy expulsion, downstream, of the air that therefore has to cross it with horizontal direction of the flow. In such heat pumps, therefore, a conveyor that deflects the direction of the air flow by 90° from vertical to horizontal is provided at the air inlet. The conveyor has an inlet whereon a vertical conduit engages that substantially is almost always preceded, as said, by at least one further deviation by 90° in an elbow.

The sudden deviations of the air flow produce strong turbulence and non- uniformity of flow and, as a consequence, greater load losses and poor distribution of air in the evaporator. This is detrimental to the efficiency of the machine and is a source of annoying noise.

After all, the machine and the feeding conduits must be designed to be as little bulky as possible and therefore there is not the possibility to have gentle connecting curves at every change of direction thereof.

As regards the prior art, for example, document US 2014000841 A 1 describes a cooling apparatus for compressed gases provided with a heat exchanger that cools said gases. To reduce the pressure drops of the gas flow that crosses said exchanger, the inlet section is provided with a rectilinear conveyor with internal divider elements arranged regularly, that uniformly divide the passage section, creating "passage channels" with geometries substantially equal to each other. The conveyor has the purpose of reducing or eliminating the flow vortices with a direction parallel to the direction of the forward speed. The invention does not provide means that uniform the forward speed, but takes into account the rotational component that the flow has while exiting from the compressor, and acts on it in order to keep the pressure drops reduced.

An object of the present invention is to significantly reduce air turbulence in the feeding conduits and in the conveyor upstream of the evaporator.

A further object of the present invention is to reduce the air noise in the same conduits and conveyor.

A further object, at least of some variants of the present invention, is to significantly improve the uniformity of distribution of the air flow at the evaporator inlet.

A further object of at least some variants of the present invention is to significantly improve the efficiency of the heal pump.

A further object of at least some variants of the present invention is to significantly improve the cooling capacity of the heat pump.

Further features and advantages of the present invention shall be better highlighted by the following description of a version of the invention in accordance with the main claims and to some preferred variants in accordance with the dependent claims, the whole illustrated, by way of a non-limiting example, in the annexed drawing tables, wherein:

- Fig. 1 shows the upper part of a heat pump suitable for using the teachings of the present invention and comprising air feeding and expulsion conduits; Fig. 2, in the details from (a) to (e), shows, in charts consisting in profiles and mappings, possible distributions of the air speeds in the various stretches of a conduit from a first stretch upstream in a straight indefinitely long zone (a) to a subsequent stretch in correspondence of an elbow (b) up to further rectilinear stretches (c), (d) and (e) downstream of the elbow and at increasing distances from the same; the profiles indicate speed patterns on the plane of symmetry of the conduit and the mappings, with different light and dark intensities speed patterns on the plane orthogonal to the axis of the conduit;

Fig. 3 schematically shows a possible conveyor according to the prior art, viewed in section along a vertical plane of symmetry;

Fig. 4 schematically shows a form of conveyor according to the invention viewed in section according to a vertical plane of symmetry;

Fig. 5 schematically shows a conveyor according to a preferred embodiment of the invention, always viewed in section according to a vertical plane of symmetry;

Figures 6. a and 6.b show a possible distribution of the average speeds of the air at the inlet of the conveyor, via a mapping on a plane orthogonal to the direction of the same speeds and via a tracking of their profile according to a plane parallel to the same speeds, respectively; Fig. 6. a also shows details of means according to the invention;

Figure 7 shows a detail of Fig. 5;

Figure 8 shows axonometrically the same conveyor of Fig. 5;

Figure 9 shows, in section according to the plane of symmetry of the feeding conduit of Fig. 1 , possible air baffles according to the invention placed in a curve present in the same conduit;

Fig. 10 schematically shows a second form of conveyor according to the invention, in section according to its vertical plane of symmetry;

Fig. 1 1 schematically shows, with more details, the same conveyor of Fig.

5 and with two additional sections on planes orthogonal to the air inlet and outlet directions in the same conveyor.

It is noted that any spatial term such as "top/bottom" possibly used hereinafter refers to the position taken by the elements that shall be described in operating conditions while terms of relative position such as "upstream downstream", "preceded/followed" refer to the order according to which the described elements are encountered by the air sent to the evaporator in operating conditions.

All aiTOws indicate the travelling direction of the air intended for the evaporator. The invention shall now be described with reference to a preferred application thereof usable in correspondence of the evaporator of a heat pump regardless of the air-air or air-water type.

Fig. 1 shows the upper part 1 (or head 1) of a heat pump HP (regardless of the air-air or air-water type) installed in a compartment V. In correspondence of the head 1 , a feeding conduit 2 guides the air drawn from the outside environment E to the heat pump HP. An expulsion conduit 3 draws air from the heat pump HP, after it has crossed the evaporator and carries it back to the outside environment E.

A possible horizontal stretch 201 starting from the outside environment E followed by an elbow 202 in turn followed by a vertical stretch 203 that engages to the heat pump HP are shown of the feeding conduit 2.

Figs. 3, 4 and 5 of the head 1 schematically show some of the main elements of the heat pump HP, that is enclosure 101 , evaporator 102, evaporator front 106, substantially flat, from which the air enters the evaporator, fan 103, conveyor 104, air inlet 105 in the conveyor 104.

The conveyor 104, per se known, may be defined as a connecting chamber between air inlet 105 and evaporator 102 having the purpose of distributing the air flow as uniformly as possible on the evaporator front 106, which is rectangular.

The changes of direction of the air flow and the changes of section from the air inlet 105 to the evaporator front 106 and, finally, the sharp-cornered shape of the conveyor 104 that, according to the prior art, as shown in Fig. 3, is simply a volume that best occupies part of the inner space of the enclosure 101 , are a major obstacle.

Such vorticity is generated only in part by the change of direction and section inside the conveyor 104 because it also depends on the presence or not of the feeding conduit 2 and on its shape as well as on the presence or not, inside such conduit 2, of suitable means for guiding the air provided by the invention to reduce the vorticity. Therefore, for the purposes of the invention, even the feeding conduit 2, at least starting from the last elbow 202 before the conveyor, must be considered, when present, as an essential part of the heat pump HP for the effects, changeable according to the invention, that it produces downstream. With reference to Fig. 2 the state of the air inside a feeding conduit 2 valid at least for air flows in heat pumps HP for household applications (100 ÷ 700 m³/h) and with diameters typical of the channels ( 100 mm ÷ 200 mm) is now examined in a qualitative manner. The resulting speeds involve an air flow that is always turbulent.

In a circular conduit, in a rectilinear stretch with stabilised air flow, i.e. that is not affected by perturbations underwent upstream, the profile of the average speeds is as in Fig. 2. a: centrally the profile is almost flat while it decreases almost linearly to the sides due to the edge effects.

A curve 202 (Fig. 2.b) due to the presence of an elbow 202 perturbs the flow; in the case of a 90° curve, the fluid streamlines are accelerated in the extrados of the curve and decelerate in the intrados generating at the exit of the curve 202 an average profile of the speeds as shown. At distance L0 = 0 from the curve 202 there is a decentralised speed peak from the axis of the piping and a low speed zone in addition to marked vortices 204. The corresponding mapping shows that the acceleration in the extrados of the curve 202 creates a "horseshoe" shaped redistribution with the concavity towards the intrados. This effect is more marked for increasing flows rates and decreasing diameters.

For increasing distances (Ll> L0) from the curve 202 the flow imbalance tends to decrease with a redistribution of the flows as in Fig. 2.c while there being vortices 204.

For L2 > LI (see Fig. 2.d), the flow redistributes even more with a speed profile that tends to that turbulent already seen in Fig. 2. a but that is actually reached only to a marked distance L3 » LI from the curve 202 (see Fig. 2.e). The air flow rate per unit of section area of a generic conduit taken orthogonally to the direction of the air flow being defined as "flow density" it is observed that such flow density is provided with central symmetry with respect to the axis of a conduit, in particular circular, where the air flow is not perturbed by upstream curves 202 (see. Figs. 2. a and 2.e) while, in addition to vortices, there is a marked central asymmetry in the stretches influenced by an upstream curve 202. Depending on the distance LO, LI , L2 or L3 between elbow 202 and air inlet 105, the distribution of the air speeds in correspondence of the air inlet 105, shall be represented by one of the distributions seen in Figs. 2.b to I.e. The narrow spaces generally available in the installation compartment V make the heavily imbalanced distributions of Figs. 2b or 2c, relating to distances L0 and LI , respectively, from the elbow 202, more likely, resulting in a marked imbalance of the flow at the air inlet 105. Such non-homogeneous flow entering the heat pump HP results in a very uneven flow density at the inlet of the evaporator 102 with consequent unbalanced operation thereof. As clear to a man skilled in the art, this causes a non-homogeneous distribution of the air temperatures as it crosses the evaporator 102; a reduction in cooling power and yield of the same follows. In fact, operations are performed at lower temperatures than those theoretically possible for any given inlet air temperature and/or the. heat in some of its areas cannot be absorbed.

Another consequence of the non-homogeneous flow is the creation of localised turbulences in the conveyor 104 with increase of noise.

Non-uniformities of the flow density and formation of vortices, however, originate, as already said, also inside the conveyor 104 regardless of the distribution of the flow density at the entrance of the same not only for the deviation substantially by 90° underwent by the air when this enters vertically from above but also for the variation of the shape of the passage section almost always circular in correspondence of the air inlet 105 and rectangular on the evaporator front 106 and always divergent from air inlet 105 to evaporator front 106. As a consequence, non-uniformities of flow density on the evaporator front 106 take place even in the absence of feeding conduit 2 provided or not with curves or elbows 202 and also if the air enters the conveyor 4 not vertically but orthogonally to the evaporator front 106 (see Fig. 10).

According to the invention, the problem of non-uniformity of flow density or at least of the air vorticity is partially solved by adopting a tapered shape for the conveyor 104 which, as shown in Figs. 4, 5, 7, 8 and 10, passes continuously and gradually from the air inlet 105 section, circular, to the outlet section in correspondence of the evaporator 102, rectangular.

According to a possible variant of the invention (see. Fig. 9), usable in conjunction with any other variant, it is provided that at least the possible elbow 202 immediately upstream of the air inlet 105 to the conveyor 104 is provided with a baffle 206 comprising fins 207 aimed at reducing the vorticity of the air inside and downstream of the same elbow 202. Such fins 207 are sheets

inside the elbow 202,

- orthogonal to the plane of symmetry of the elbow 202,

with circle arc section concentric to the curvature of the elbow 202, appropriately spaced among them to guide the air flow in the passages 208 defined by them.

Thanks to the baffle 206. the air flow exits from the elbow 202 substantially undisturbed according to a speed profile that, regardless of the effect of edge on all the walls of the elbow 202 and of the fins 207, is substantially and almost immediately that which, in the absence of baffle 206, is taken from the air only at said distance L3 from the elbow 202. Ultimately, the air speeds profile that is obtained at the air inlet 105 is substantially that devoid of vortices shown in Fig. 2.e.

According to a preferred embodiment of the invention, a reduction of the vortices inside the conveyor 104 is obtained, with reference to Figs. 5, 6, 7, 8 and 10, by providing the same conveyor 104 with a plurality of flow guides 107 adapted to form channels 108 that guide the air flow from the air inlet 105, where they have an inlet section of area Ai, towards the evaporator front 106 where they have an outlet section of area Si.

From now on a conveyor 104 provided with said channels 108 will be referred to as channelled conveyor 104.

Preferably, such flow guides 107:

- are parallel to the prevailing direction of the air flow entering the channelled conveyor 104 in correspondence of their connecting edge 1 12; are orthogonal to the exchanger front 106 in correspondence of their outlet edge 1 13.

Preferably, for constructional reasons, such flow guides 107 the outermost thereof may be two opposed walls 109 of the channelled conveyor 104 are sheets of thin thickness that:

start from a connecting edge thereof 1 12 upstream, substantially from the air inlet 105, up to an outlet edge 1 13 thereof downstream towards the evaporator front 106;

- extend crosswise, i.e. orthogonally to the plane of symmetry of the conveyor 104 for a width Li (see Figs. 8 and 1 1) up to the sides 1 10 of the same channelled conveyor 104;

are each distant from the subsequent by an average distance Di.

The shape of the section of each channel 108 and the corresponding area Aci vary from upstream to downstream along the flow guides 107 from said inlet Ai and outlet Si values but very preferably gradually, without discontinuity.

Preferably and wherever possible, the section of each channel 108 is extended in a cross direction; in other words, preferably and wherever possible the average distance Di between two consecutive flow guides 107 is less than its width Li. This is clearly in order to limit the formation of vortices.

The means shown so far according to the invention are adapted to eliminate the vorticity of the air in a more and more effective way, whether severally or jointly used.

Nonetheless a non-uniform air flow as regards to flow density may flow into the evaporator front 106 even providing for the flow guides 107 because the air speed exiting from the channels 108 may be different from channel to channel. According to a further improvement, at least some of the flow guides 107, except for the outermost two if consisting in the two opposing walls 109 of the channelled conveyor 104. can stop at a distance from the evaporator front 106 sufficient for forming plenums (not shown in the figures) between outlet edges 1 13 and evaporator front 106 in which the various speeds have the possibility to uniform while giving rise to some swirling motion.

According to a further very preferred improvement, the flow guides 107 end substantially in contact with the evaporator front 106 with sections of the channels 108, at the outlet edges 1 13, of such an outlet area Si that in correspondence, the air flow density is substantially equal for each channel and, consequently, there is a feeding at the same flow density in each zone of the , evaporator front 106. This is obviously equivalent to say that the air must exit at the same speed from all channels 108.

Since the widths Li of each channel 108 are not necessarily but very suitably to be chosen as large as possible starting from the air inlet 105 (with an upper limit substantially imposed only by the dimensional constraints of the evaporator 102 and the head 1 of the heat pump HP), the appropriate size of each inlet area Ai substantially depends on the appropriate choice of each corresponding average distance Di in correspondence of the connecting edges 1 12. Having established the size of each inlet area Ai, and thus the air flow rate that enters it, the condition that in correspondence of the outlet edges 1 13 there is substantially uniform flow density for all the channels 108, determines the corresponding outlet areas Si being it understood, as said, that then the variation of section of each channel 108 from inlet to outlet is very appropriate to be gradual.

Fig. 6 shows a simple way to meet such condition. It shows a vertical stretch 203 of a feeding conduit 2 at a distance LI from a preceding elbow 202, and thus with marked differences in speed. At a distance just over LI, the vertical stretch 203 engages in the air inlet 105. The sections of the channels 108 have, at the connecting edges 1 12, the shape of circle sectors comprised among successive parallel cords apart from each other of Di. The areas Al , A2,..., Ai,.., A6 of the sections are variable according to the speed of the inlet air, so that each channel 108 intercepts an equal air flow. At this point it is sufficient that the outlet areas Si are all equal to each other to feed the evaporator 102 uniformly. The all equal outlet areas are obtained, in turn, by simply placing the widths Li all equal to the width of the evaporator front 106 to the outlet edge and so the distances Di all equal as well.

Such a simple solution, however, may be not the best from the fluid dynamics efficiency point of view because it may result in markedly divergent channels 108 (those that start with very small inlet area Ai because they intercept air where it has the highest speeds) with possible formations of vortices and, on the other hand, also converging channels.

When applicable, a better method for the selection of the sections of the channels 108 is to impose that in each of them the area of the section is a constant fraction of the total inlet-to-outlet passage area. In formulas, said A the sum of said inlet areas Ai and S the sum of the outlet area Si, arises, for each i-th channel 108 of the n channels 108, Ai/A = Si/S and the condition that such a relationship is maintained throughout the development of each channel; in such way channels 108 with all uniformly divergent sections are obtained being A < S.

Additionally, it may be provided to assign to each ratio Ai/A a value always equal or, preferably, different for one or more channels 108 to obtain channels 108 the section areas whereof are a greater fraction than that chosen for other channels; this way channels 108 of greater passage section may be obtained where it is deemed less necessary to guide the air (because of lower speed and/or subject to less sudden changes of direction).

In general, an amount of alternative choices is obviously possible, the distribution conditions of the air speeds at the air inlet 105 being equal, by varying at least both the number of flow guides 107 and the distances Di between them.

Fig. 7, which indicates on a scale a concrete possible distribution of the flow guides 107 according to to the invention, shows a solution where the distances Di between two subsequent guide walls 109 are, despite the previous example, markedly different also in the proximity of the evaporator 102 and, therefore, the outlet areas Si are equally different and this according to a non-intuitive sequence of distances Di but that actually takes into account a plurality of geometric and fluid dynamic factors that a man skilled in the art knows well such as, by way of a non limiting example:

constraints to the widths Li placed by the diameter of the air inlet 105 and the diverging pattern of the sides 1 10;

load losses along the surfaces of each channel 108;

limits to the degree of divergence of each channel 108 to prevent stalls; limits to the distances Di in order to avoid formations of vortices;

practical limits to the number of channels 108;

variability of the distribution of the inlet air speeds within reasonable margins (for example according to predefined max. and min. limits of the distance L of an elbow 202 from the air inlet 105);

etc.

Such conditions are all interdependent and the multiple solutions are obtained only recursively with fluid dynamics simulations to the computer through one or more specialised software.

For example, the setup of Fig. 7 has been found by using the following well- known software: Ansys Meshing, ANSYS CFX, ModeFRONTEER whose performance does not need to be detailed being it known to the experts in fluid dynamics.

Also the quantification of the distribution of the air speeds in various points of a duct downstream of an elbow with or without baffle 206 and in correspondence of the air inlet 105 may be performed both experimentally and with the aid of fluid-dynamic simulators.

If necessary, the design of the baffle 206 may also use the above software.

It is understood that, according to the preferred embodiment of the invention, the indispensable condition placed to determine the shape of the channels 108 is that air at variable flow density from zone to zone exits form all of them towards the evaporator 102 within predetermined margins deemed acceptable where such margins substantially depend on the expected or acceptable range of variability of the air speed at the air inlet 105.

Since it has been seen that the distribution of the air speed is a close function of the distance L of an elbow 202 from the air inlet 105, the said expected or acceptable range of variability of the distribution of the air speed at the air inlet 105 is equivalent to placing an expected or acceptable range of variability of the distance L of said elbow 202 from said air inlet 105.

Of course, if the expected range of variability for said distance is excessive for obtaining a flow density variable from zone to zone within acceptable margins, the channelled conveyor 104 may be provided in multiple versions each optimised for a particular range of variability of the said distance L.

However, it has also been seen that the use of a baffle 206 inside the elbow 202 closest to the air inlet 105 makes the distribution of the same air inlet speeds substantially uniform regardless of the amount of said distance L, therefore, the combined use of such deflector 206 and channels 108 makes sufficient, for each model of heat pump HP, a unique version of channelled conveyor 104 which is the same as saying that the expected range of variability is also acceptable.

Such a unique version of channelled conveyor 104 may also be usable in the event that the entering air at the air inlet 105 does not come from a feeding conduit 2 but from the heat pump installation compartment V.

The invention naturally applies to conveyors 104 with any relative position between air inlet 105 and evaporator front 106; in particular, the invention, as described, applies to the case where air enters horizontally into the conveyor 104, as in the case of Fig. 10.

By applying the invention it has been found experimentally that the COP of a heat pump with air evaporator may be improved even by 16%.

It is clear that the invention, although only described with reference to the case of an evaporator 102 preceded by a conveyor 104 of a heat pump (HP) is applicable to any conveyor 104:

associated with a heat exchanger 102 between air and another means, where said conveyor 104 is intended to guide the entry of said air towards the air-side exchanger front 106 of the same heat exchanger 102, said exchanger front 106 being substantially flat,

where in particular such a heat exchanger 102 may be the evaporator or the condenser of a heat pump.

What described may be extended and applied to any air conduit where it is appropriate to straighten or guide the air flow before encountering a heat exchanger, such as for example in an evaporator or a condenser.

Claims

Conveyor ( 104) associated with a heat exchanger (102) between air and another means intended to guide the inlet of said air towards the air-side exchanger front (106) of the same heat exchanger (102), said exchanger front ( 106) being substantially flat,

characterised in that:

- said conveyor (104) has a tapered shape that continuously and gradually passes from the circular air inlet ( 105) section to the outlet section in correspondence to the same exchanger (102),

- said conveyor (104) is provided with a plurality of flow guides ( 107) adapted to form channels (108) that guide the air flow from said air inlet ( 105), where they have an inlet section of area Ai towards said exchanger front ( 106) where they have an outlet section of area Si,

- said channels ( 108), in correspondence of the outlet edges ( 1 13), have such an outlet area Si that the air flow density is substantially equal for each channel ( 108) and, as a result, there is a feeding at the same flow density in any zone of the exchanger front ( 106).

Conveyor (104) according to the previous claim,

characterised in that:

said flow guides (107)

- are parallel to the prevailing direction of the air flow entering said conveyor (104) in correspondence to their connecting edge (1 12); are orthogonal to said exchanger front (106) in correspondence to their outlet edge ( 1 13).

Conveyor ( 104) according to any claim from 2 onwards,

characterised in that

said flow guides (107)

- start from said connecting edge (1 12) substantially to said air inlet ( 105); - extend crosswise up to the sides ( 1 10) of said conveyor ( 104). Conveyor ( 104) according to any claim from 2 onwards,

characterised in that

the said sections of each of said channels ( 108) are extended in cross direction.

Conveyor ( 104) according to any claim from 2 onwards,

characterised in that

at least some guides of said flow guides (107), except for the outermost two if consisting in the two opposed walls ( 109) of said conveyor ( 104), may stop at a distance from said exchanger front ( 106) sufficient for forming plenums between said outlet edges ( 1 13) and the exchanger front ( 106).

Conveyor (104) according to any one of claims 1 to 4,

characterised in that

said flow guides ( 107) end substantially in contact with the said exchanger front (106) with sections of said channels ( 108) at said outlet edges (1 13) with such an outlet area Si that in correspondence, the air flow density is substantially equal for each one of said channels (108).

Conveyor (104) according to the previous claim,

characterised in that

the said sections of said channels (108) have, at said connecting edges (1 12) areas Al, A2,..., Ai,.., A6 variable according to the speed of the inlet air, so that each of the same channels ( 108) intercepts an equal air flow.

Conveyor (104) according to claim 6,

characterised in that

the said sections of said channels (108) are, from inlet to outlet, a constant fraction Ai/A = Si/S of the total flow area.

Conveyor ( 104) according to the previous claim, characterised in that

said constant fractions Ai/A = Si/S of the total flow area have a different value for one or more of said channels (108) in particular in order to make said channels (108) of larger flow section where it is deemed less necessary to guide the air.

Conveyor (104) according to the previous claim,

characterised in that

the arrangement of said flow guides (107) is that shown in scale in Fig. 7.

Conveyor (104) according to any claim from 6 onwards,

characterised in that

said conveyor (104) is provided in multiple versions each one optimised for a particular range of variability of the inlet air speeds and/or for a particular range of variability of the distance L of an optional elbow (202) from said air inlet (105).

Air-air or air-water heat pump (HP) where a conveyor ( 104) is provided in order to direct the air constituting the heat source for the evaporator (102) towards the evaporator front (106) of the same evaporator (102),

characterised in that

it conforms to one or more of claims 1 to 1 1.

Air-air or air-water heat pump (HP) according to the previous claim, characterised in that

it is provided, upstream of said conveyor (104), with a feeding conduit (2) comprising at least an elbow (202) followed by a stretch of horizontal conduit (201),

said elbow (202) being provided with a baffle (206) comprising fins (207) aimed at reducing the vorticity of the air inside and downstream of the same elbow (202).

Air- air or water- air heat pump (HP) where a conveyor ( 104) is provided in order to direct the air constituting the heat source for the condenser (102) towards the condenser front (106) of the same condenser ( 102),

characterised in that

it conforms to one or more of claims 1 to 1 1.