EP0943876B1 - Heat exchanger or heat pump with cross flow fan - Google Patents

Abstract

The heater/cooler or pump has a heat exchanger, a tangential fan in a chamber (16) with a spiral outlet (15) and a porous deflector (10). The fan has no spiral projection (21) on its intake side, while its rotor blades (23) are inclined at an angle of over 50 degrees. Planes taken from the tip (20) of the deflector and the nearest point on the housing on the fan's intake side meet at an angle of over 180 degrees at the center of the rotor.

Description

This invention relates to a machine for heating or cooling the atmosphere, such than a hot or cold transmitter or a heat pump heat including a tangential fan.

Tangential fans include a paddle wheel which sucks the ambient gas in a direction perpendicular to its axis of rotation and the returns in another direction perpendicular to this axis. They have the advantage of offering a high flow for a small footprint, but their job in home applications is problematic because of their noise, normally too high to meet current standards on devices discussed here. This is why common air conditioners include fans helical (flow in the axis of rotation of the impeller) or centrifugal (with flat ejection flow and radiating over a full circle). These two kinds of fans, however, require large areas of air flow, and therefore a large area apparatus. The object of the invention was to rehabilitate tangential fans for uses domestic thanks to a particular construction which makes them quieter. A group of measures is proposed in combination to achieve this result. One of them is to make a piece of glass porous protrusion, called lacrosse beak, which partially forms a chamber in which the wheel turns and which points to a wheel generator. Lacrosse beak porous has already been proposed in US-3 patent 695,775 A, but this is considered to be insufficient for the application envisaged here, where the requirements are strict.

That is why it still conforms to the invention that the fan does not have a nozzle scroll at the entrance, and the fan wheel is fitted with blades with pitch angle greater than 50 °. Other provisions, particularly favorable for improve flow, have been adopted in the emitter as the heat pump and are offered at incidental title.

• la figure 1 est une coupe de côté d'un émetteur de chaud et de froid conforme à l'invention,
• la figure 2 est une vue de face de ce même émetteur,
• la figure 3 illustre plus précisément son ventilateur,
• et la figure 4 est une vue d'une pompe à chaleur conforme à l'invention.

The characteristics, advantages and aims of the invention will be better understood from the commentary to the following figures, which are given by way of illustration and not limitation:

• FIG. 1 is a side section of a heat and cold emitter according to the invention,
• FIG. 2 is a front view of this same transmitter,
• FIG. 3 illustrates more precisely its fan,
• and Figure 4 is a view of a heat pump according to the invention.

The description first relates to the figure 1. A transmitter according to the invention is attached to a wall and its envelope has a triangle-shaped section irregular whose longest rear side is side of the wall, the upper side, slightly tilted towards the bottom from the wall, is the shortest and the side lower, oblique, connects to the previous one by a tip 1. The lower side has an opening air inlet 2 veiled by a filter grid 3 and, above this entry 2 but just below tip 1, a first air outlet 4; a second air outlet 5 is arranged across the side top of the envelope, slightly above the tip 1. These air outlets 4 and 5 are furnished with fins 6 and 7, directed downwards and outwards for the first exit 4 and up and out for the second outlet 5. A heat exchanger 8 is arranged in the envelope, behind the grid 3; he consists of a network of tubes 9 of circular section which lead to two conduits 10 assigned to the supply and return of a liquid, refrigerant or circulating as the case may be. The conduits 10 extend side of the envelope and out of it before join an appropriate facility that is part of the building in which the transmitter is installed. A tray 11 is located under the tubes 9 for if necessary collect the humidity of the air which has condensed on them. A purge duct, which can be open at will and not shown, allows you to empty it.

The centerpiece of the aircraft is a tangential fan 12 placed in an envelope 13 internal to the outer sectional enclosure triangular. This internal envelope 13 includes a entrance pavilion 14 ending in front of the heat 8, an outlet volute 15 ending in front of the air outlets 4 and 5 (which converge) and a chamber 16 intermediate to the previous ones and which houses the wheel 17 of the fan 12. Before getting to essential characteristics of the invention, let us note that a flap 18 is articulated to the outer envelope of the transmitter and oscillates between two extreme positions where it closes one or other of the air outlets 4 and 5 while directing the air coming out of volute 15, up to which it extends towards the other air outlets 4 and 5. This arrangement optimizes the dissemination air in the ambient atmosphere according to its temperature: hot air tends to rise, it is the first air outlet 4 which will be opened for heat the building so that the air is first blown down before rising; the second air outlet 5 will be open when using the device as an air conditioner to blow cold air to the high before it falls. Another view of the transmitter is constituted by FIG. 2, where we further distinguishes motor 26 from fan 12. The impeller 17 is possibly quite long, depending on the flow of air and the heating or cooling power requested.

Figure 3 shows in more detail the fan 12. Aerodynamic studies show that the air is blown out locally by taking a vortex aspect in the extent of a vortex V. This vortex V would be located in the center of the wheel 17 if it was in the center of a circular chamber but the resulting flow would then be zero. So that the fan 12 works, chamber 16 is therefore asymmetrical, and the internal envelope 13 present at particular an inward projection, which is called traditionally a butt stock 19 and which extends almost to wheel 17 where it runs towards the entrance pavilion 14: the air which accompanies the wheel 17 around it is stopped and disperses either towards exit 15, i.e. towards the center of wheel 17, and it forms the Vortex V, which is like hanging on the tip 20 of the butt end of the butt 19 because it is a little distance. This arrangement gives full satisfaction for fan efficiency 12 but the proximity to the wheel 17 and buttstock 19 produces a hissing sound which is a major cause of excessive noise from tangential fans.

This hissing sound can be reduced if the mouthpiece butt 19 is porous. Such a provision is therefore adopted here: in a concrete embodiment, the beak of butt 19 is a piece of perforated sheet metal whose pores occupy 32% of the surface. A return current towards the entrance pavilion 14 is therefore tolerated through the pores, but the air flow supplied by the fan 12 is still good enough, and it is moreover possible to lengthen the butt end 19 compared to previous solutions for it to come closer to wheel 17 (at ten millimeters per example); we also have it more downstream than it is not usual, in order to increase the flow. The effect of noise reduction is reinforced by a form the inner envelope 13 on the side opposite the butt end 19: its upper surface 22 is approximately planes upstream of the flow to beyond the impeller 17, which is achieved by removing a spout volute 21 (dotted) traditional which tightens the entrance pavilion 14 in front of wheel 17 and therefore encourages the air to enter to be better trained, but is also accompanied by an increase in noise. he results from this deletion and the position of the spout butt 19 that the angle λ turned upstream, traced between the point of the closest upper surface 22 of the wheel 17 and the tip 20 of the butt end 19, and whose top is the center of the wheel 17, is more important, significantly higher than 180 °, while a angle much smaller than this value is usual.

Other provisions may relate to blades 23 of the wheel 17. A good design, that of a prototype built, anticipates that they are at number thirty and range between diameters of 60 mm and 49.44 mm from wheel 17; their rope C (distance taken on a straight line between their ends) is 6.3 mm, their camber angle  of 72.55 ° and their setting angle γ (between chord C and tangent wheel 17 taken at the inside diameter) is 53.18 °. This last value, greater than 50 °, is important, because the inventors have found that an angle significant stalling helped make the fan 12 more efficient and even less noisy, although the air entrainment reaching the wheel 17 after having crossed the entrance pavilion 14 was less easy, because the flow was on the contrary improved at the part which extends in front of volute 15 and near the butt end 19 and moreover functions as a turbine, the drag of the air being reduced there. The flow is even easier if the volute 15 folds towards the entrance pavilion 14, and more precisely if the lower surface 24 and 25 of the internal envelope 13 forms an angle β acute on either side of the butt 19: this angle is obtuse in existing fans. This particularity is only exploited here when part 18 directs the flow to the first air outlet 4, whose lower surface 25 delimits the duct.

Acoustic tests finally shown that diffuse noise produced by the flow of the air through the fan 12 and which is added to the hiss produced at the butt end of the butt 19, became predominant at high speeds. We therefore advise run fan 12 at low speed and small speed, i.e. below performance possible and usually chosen: the noise of the flow then becomes weak, and the hissing sound predominant, so that the porosity of the butt end 19 makes his advantage much better. A speed less than about 1000 rpm advocated.

An auxiliary provision consists of place the blades 23 in a spin along the wheel 12, to prevent them from passing periodically in front the butt end 19, which would produce beats and sound peaks at these frequencies. Such a pale 23 twisted is illustrated in Figure 2. We finally notice that a characteristic of tangential fans 12 is to raise the air pressure more strongly than other kinds of fans, so that 8 thicker heat exchangers or longer tubes tight, and therefore more temperature variations large for the air passing through the device, are possible.

These considerations, discussed so far for an air emitter, still apply to a pump heat. Such a device extracts heat from a cold source and brings it to a hot source by a fluid traversing a closed circuit which makes it pass alternately by two heat exchangers located at thermal sources, and in which, in general, vaporizes and condenses respectively; a compressor and a regulator are placed respectively on the two branches of the circuit which connect the exchangers. A another aspect of the invention does not, however, relate to the organization of a heat pump but on the provision of ventilation means which facilitate air circulation in the room to be heated or cool through the heat exchanger correspondent: these means can be placed from the as shown in figure 4, in a fan unit 30 seen from above and comprising a section wall 31 rectangular enclosing two compartments 32 housing each a heat exchanger 33, diagonally in the compartment, and a fan 34 in a corner of the compartment; exchangers 33 form an open vee towards a suction face 35, screened, from the block fan 30 and the fans 34 are still arranged at two corners of the fan unit 30: the air flow enters block 30 from the face suction 35 in a uniform flow before fork towards the fans 34 by crossing the exchangers 33 by their smallest dimension; he leaves the fan unit 30 through openings mesh 36 which occupy part of its faces lateral; a partition 37 separating the compartments 32 ensures the symmetry of the flow.

The fans 34 are analogous to the fans 12 of the previous embodiment and include in particular a porous butt end 38, analogous to the butt end 19 already encountered. All other improvements concerning the wheel, its arrangement in fan casing and shape of this envelope can be adopted or not. However, the requirements for acoustic discretion may be smaller for heat pumps, which have always been noisy.

It would be possible not to duplicate the fans 34 and exchangers 33, but the provision proposed here has the advantages of allowing wider air dispersion, a reduction in fan block height 30 and less power fans 34.

The fan unit 30 is isolated from the rest of the pump, which belongs to a compressor block 41 placed in another room, not devoted to the house, so that we don't have to hear its noise, which comes mainly from a compressor 42 attached to a motor not shown; the compressor block 41 also includes a heat exchanger 43 communicating with the cold source (if the room in which is the fan block 30 must be heated) and a regulator 44. All of these are interconnected by a circuit of conduits 45 which also passes through exchangers 33, where it branches off.

Claims (8)

1. Air blower or heat pump comprising a heat exchanger (8, 33) and a tangential fan (12, 34) housed in a chamber (16) preceding an air outlet volute (15), the chamber being formed partly by a porous snout (19, 38) pointing towards a wheel generator of the fan, characterized in that the fan has no volute tongue (21) and in that the wheel of the fan is fitted with blades (23) with a pitch angle (γ) greater than 50°.
2. Air blower or heat pump according to Claim 1, characterized in that an angle (λ) directed upstream, passing through the end (20) of the snout and the casing point (13) of the fan closest to the fan wheel (17) on an intrados side, and having the centre of the wheel as apex, is greater than 180°.
3. Air blower or heat pump according to either of Claims 1 and 2, characterized in that the snout (19) is a perforated metal sheet.
4. Air blower or heat pump according to any one of Claims 1 to 3, characterized in that the fan is housed in a casing (13) with an intrados (24, 25) forming an acute angle (β) on each side of the snout (19).
5. Air blower or heat pump according to any one of Claims 1 to 4, characterized in that the wheel of the ventilator is fitted with twisted blades (23).
6. Air blower according to any one of Claims 1 to 5, characterized in that the wheel (17) has an axis of horizontal rotation, the volute (15) ends in two bifurcating and superimposed ducts, and a shutter (18) allows the ducts to be selectively closed as desired, one of the ducts being ascending and the other of the ducts being descending.
7. Heat pump according to any one of Claims 1 to 5, characterized in that the fan (34) is housed in a corner of a rectangular fan unit (30), the heat exchanger (33) lies along a diagonal of the unit, the air enters the unit via a face (35) on the long side of the rectangle leading to the exchanger and leaves the unit via a face (36) on the short side of the rectangle leading to the volute.
8. Heat pump according to Claim 7, characterized in that it comprises two ventilator units, the heat exchangers form a V, the air inlet faces are contiguous and the air outlet faces are opposed.

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