EP0082764A1 - Refrigeration circuit with motor compressor, and heat pump provided with such a circuit - Google Patents

Abstract

Refrigeration circuit with motor compressor, comprising a vertical composite suction manifold (6) fulfilling the function, in addition to its true function of suction manifold, of an anti-knock bottle and of an atomiser/pump effecting without damage to the motor compressor (2) the return to the latter of the lubricant and of the liquid refrigerant trapped in the circuit, and an evaporator (5) divided into a number of vertically spaced sections which are mounted in parallel between this manifold (6) and the pressure-reducing valve. This vertical composite suction manifold (6) consists of an elongate body (9) provided in its enclosed space with a capillary tube (11), the lower end of which is submerged in the mass of trapped liquid refrigerant and lubricant, and the upper end of which forms with the narrowed part (10) of the elongate body (9) a Venturi tube which, during the passage of the gaseous refrigerant called by the motor compressor (2), sucks and atomises the trapped lubricant and liquid refrigerant. Application to a heat pump in which the condenser forms, with an independent circuit of heat-exchanging fluid, a heat exchanger. <IMAGE>

Description

The present invention relates to a refrigeration circuit with a compressor, and a heat pump provided with such a refrigeration circuit.

Refrigerant circuits with a motor-compressor usually comprise in a closed circuit, mainly, a motor-compressor, a condenser and an evaporator. However, in these refrigeration circuits with a compressor, a distinction is made between those which have a wet type evaporator and those which are provided with a dry type evaporator. The structure and operation of wet type evaporator circuits are different from that of dry type evaporator circuits. In a wet type evaporator refrigeration circuit, the evaporator is directly and partially filled with refrigerant in the form of a liquid, and this liquid refrigerant evaporates there to give cold. In addition to the temperature of the surrounding medium, the rate of evaporation of the liquid refrigerant in this wet type evaporator depends in particular on the size of the surface developed by this evaporator. Thus, a wet type evaporator refrigeration circuit generally comprises a large capacity evaporator with a large heat exchange surface, and a means which ensures the passage of the liquid refrigerant in the evaporator and the adjustment of the filling level of the latter in liquid refrigerant. This means is usually constituted by a valve of the float type for example. In a dry type evaporator refrigeration circuit, the evaporator is supplied with refrigerant in the form of mist or fine droplets. This refrigerant in the form of a mist coming into contact with the wall of the evaporator evaporates quickly and produces cold. As a result, in a dry type evaporator refrigeration circuit, the usual a Lely a relatively average capacity and heat exchange surface, and that the residual refrigerant in the form of liquid which is in this evaporator is generally in insignificant or low quantity.

A dry-type evaporator refrigeration circuit frequently includes an anti-blow bottle placed between this evaporator and the motor-compressor. This anti-blow bottle although it increases the price of the circuit prevents the residual liquid refrigerant from entering directly into the motor-compressor and causing mechanical damage.

In a refrigeration circuit, the gaseous refrigerant discharged by the motor-compressor usually carries with it lubricant intended for the latter. This wandering lubricant is often trapped in the low pressure part of the circuit, especially in the downstream part of the evaporator and stays there.

As a result, after a certain operating time, the motor-compressor becomes insufficiently lubricated.

In an application to a heat pump, in particular that intended for space heating, this refrigeration circuit is associated, through a heat exchanger, with a circuit of heat transfer liquid. The refrigeration circuit of the heat pump is in this case either organized in its arrangement in two parts, one remaining inside the premises mainly comprising a motor-compressor, a condenser and a heat exchanger and the other installed at the exterior of these premises mainly comprising an evaporator is organized in a compact arrangement, in a single block, suitable for being installed outside the premises. The refrigeration circuit of such a heat pump must have safety, resistance to mechanical and weathering characteristics, acoustics, efficiency, bulk, etc.

The present invention makes it possible to produce an improved refrigeration circuit with an evaporator of the dry, economical type which has excellent characteristics in its application to a heat pump and in particular to that contributing to the heating of premises, and does not have the drawbacks mentioned in of the previous paragraphs. The invention also relates to the production of an economical, solid heat pump, effective in its contribution to space heating.

According to the invention, the refrigerant circuit with a motor-compressor having in closed circuit, mainly a condenser, an expansion valve, a dry-type evaporator, a suction manifold disposed between this evaporator and the motor-compressor, comprises in the interval between the regulator and the compressor, a connection pipe, a vertical composite suction manifold and an evaporator divided into several vertically spaced sections, mounted in parallel between this composite suction manifold and this pressure reducer, this vertical composite suction manifold also playing its role as an evaporator collector, the role of an anti-blow bottle and that of a pump-sprayer providing a return to the motor-compressor and without damage to the latter, lubricant and liquid refrigerant trapped in the circuit.

• - la figure 1 représente une vue schématique d'un circuit frigorifique à évaporateur du type à sec réalisé selon l'invention,
• - la figure 2 représente une vue schématique d'une partie du circuit de la figure 1,
• - la figure 3 représente une vue schématique du circuit frigorifique de la figure 1 appliqué à une pompe à chaleur réalisée selon l'invention,
• - la figure 4 représente une vue schématique et partielle d'une coupe longitudinale d'une partie de l'échangeur thermique de la pompe à chaleur indiquée dans la figure 3,
• - la figure 5 représente une vue schématique et partielle d'une coupe verticale de la pompe à chaleur indiquée dans la figure 3, dans sa disposition compacte en un seul bloc,
• - la figure 6 représente à une autre échelle une vue schématique et partielle d'une coupe verticale de la pompe à chaleur indiquée dans la figure 3, dans sa disposition en deux parties,
• - la figure 7 représente à une autre échelle une vue schématique et partielle d'une coupe verticale d'une variante de réalisation de la pompe à chaleur indiquée dans la figure 3, dans sa disposition compacte, en un seul bloc, et
• - la figure 8 représente à une autre échelle une vue schématique et partielle d'une coupe verticale de la variante de réalisation de la figure 7, dans sa disposition en deux parties.

To better understand the invention, a number of embodiments are described below, illustrated by attached drawings,

• FIG. 1 represents a schematic view of a refrigeration circuit with an evaporator of the dry type produced according to the invention,
• FIG. 2 represents a schematic view of part of the circuit of FIG. 1,
• FIG. 3 represents a schematic view of the refrigeration circuit of FIG. 1 applied to a heat pump produced according to the invention,
• FIG. 4 represents a schematic and partial view of a longitudinal section of a part of the heat exchanger of the heat pump indicated in FIG. 3,
• FIG. 5 represents a schematic and partial view of a vertical section of the heat pump indicated in FIG. 3, in its compact arrangement in a single block,
• FIG. 6 represents on another scale a schematic and partial view of a vertical section of the heat pump indicated in FIG. 3, in its arrangement in two parts,
• FIG. 7 shows on a different scale a schematic and partial view of a vertical section of an alternative embodiment of the heat pump indicated in FIG. 3, in its compact arrangement, in a single block, and
• - Figure 8 shows on another scale a schematic and partial view of a vertical section of the alternative embodiment of Figure 7, in its arrangement in two parts.

A refrigeration circuit 1 produced according to the invention comprises in closed circuit mainly a motor-compressor 2, a condenser 3, a capillary 4 serving as an expansion valve and an evaporator of the dry type 5.

In this refrigeration circuit, the gaseous refrigerant is compressed by the motor-compressor 2, discharged into the condenser 3 where the refrigerant condenses in the form of liquid and gives off heat.

This liquid refrigerant passes through a pressure reducer constituted by a capillary 4, expands in the form of mist or fine droplets in the evaporator 5 where it evaporates by absorbing heat in other words produces cold before returning to the motor-compressor 2 under the suction action of the latter. Practically the residual liquid refrigerant remaining in the evaporator 5 is insignificant or weak. The evaporator 5 is thus called the dry type evaporator.

According to an important characteristic of the invention, a vertical composite suction manifold 6 is mounted in this refrigeration circuit 1, between the motor-compressor 2 and the evaporator 5.

According to another characteristic of the invention, the evaporator 5 is divided into several vertically spaced sections, mounted in parallel between the regulator 4 and the vertical composite manifold suction 6. The outlet ends of these sections lead respectively to different points of the height of this composite suction manifold 6. The number of these sections is greater than or equal to two. In the example illustrated (FIGS. 1 and 2) the evaporator 5 comprises three superimposed sections 5a, 5b, 5c mounted in parallel. The capacity of the evaporator and consequently that of its superimposed sections mounted in parallel are determined so that in the operation of the refrigeration circuit 1, the residual liquid refrigerant only fills one of these sections of the evaporator 5 as much as possible. , the lowest section 5a, and the lower part of the composite manifold 6. Therefore, a large part of the evaporator 5 remains constantly available for the reception of the refrigerant mist and for the evaporation of the latter. The risk of a return of the liquid refrigerant in the motor-compressor is thus effectively avoided. Such a risk can occur more easily in a wet type evaporator refrigeration circuit, a large part of which is precisely filled with refrigerant in the form of liquid.

The vertical composite manifold 6 plays, in addition to its proper role as an intake manifold, the role of an anti-blow bottle and that of a sprayer-pump producing without damage to the compressor 2, the return to the latter of the lubricant and residual liquid refrigerant trapped in the circuit.

In fact, the gaseous refrigerant expanded in the evaporator 5 borrows the vertical suction manifold 6 to return to the motor-compressor 2, through a connection pipe 7.

The lubricant part of the compressor 2, driven by the coolant stream, and the residual liquid coolant tend, at the outlet of the evaporator 5, to separate from the gaseous coolant and fall down into the lower part 8 of the manifold vertical 6. The manifold 6 thus allows the gaseous refrigerant to get rid of the liquid refrigerant beforehand and to return alone in gaseous form to the motor compressor 2. Mechanical damage liable to be caused by a liquid penetrating into the compressor are thereby avoided. The vertical composite suction manifold 6 thus plays, apart from its proper role of suction manifold, also the role of an anti-blow bottle and advantageously replaces it.

According to the invention, the vertical composite manifold 6 comprises on the one hand an elongated body 9 having a cross section larger than that of the connecting pipe 7, closed at its lower end 8, narrowed at its upper end 10 at the level of its connection to this connecting pipe 7 and in communication at several points on its side wall with the evaporator 5 and on the other hand within the enclosure of this body 9 and over almost the entire length of the latter, a capillary 11, the lower end of which is immersed in the mass of lubricant and liquid coolant trapped in the lower end 8 of the manifold 6 and the upper end disposed coaxially in the narrowed portion 10 of the upper end of this manifold. The narrowed part 10 of the upper end of the manifold 6 and the upper end of the capillary 11 create during the passage of the gaseous refrigerant called by the motor compressor 2, a venturi which sucks in lubricant and liquid refrigerant, trapped in the part 8 of the collector 6, pulverizes them and mixes them with the gaseous refrigerant stream returning to the compressor 2. This return of sprayed liquid refrigerant and lubricant does not damage the compressor 2 but also eliminates the defect or insufficient lubrication of the compressor encountered in the known refrigeration circuits.

In a refrigeration circuit with a wet type evaporator, the use of such a pump-sprayer to evacuate liquid refrigerant and trapped lubricant is practically not possible since the evaporator of this type is intended precisely to be directly supplied with refrigerant in the form of a liquid, the evaporation of which produces cold.

In its application to a heat pump 12 shown in Figure 5 and indicated by a rectangle in broken lines in Figure 3, the refrigeration circuit 1 comprises a condenser 3 which form with an independent heat transfer fluid circuit 14, a heat exchanger 13 indicated by a rectangle in broken lines. The heat exchanger 13 is according to the invention preferably constituted by two separate coaxial circuits 3 and 14 of two different fluids, one of which is the hot compressed refrigerant discharged by the compressor 2 and the other is a heat transfer fluid consisting of l for example. The heat transfer fluid circuit 14 is constituted (FIG. 4) by a pipe 15 mounted coaxially in a pipe 16 forming the condenser 3. The pipe 15 in which the heat transfer fluid circulates is, in this exchanger 13, completely surrounded by hot compressed refrigerant evolving in the pipe 16 of the condenser 3. The heat exchange between these two fluids can thus be done in an efficient manner. This efficiency is enhanced when the stream 17 of heat transfer fluid and the stream of hot compressed refrigerant indicated by the arrows 18 are directed in opposite directions. The exchanger 13 then constitutes a counter-current exchanger.

In a contribution to space heating, the heat transfer fluid circuit 14 is connected, through two valves 19 and 20, by its two ends to the inlet and to the outlet of a valve 21 of a space heating circuit. 22. The heating circuit 22 comprises, for example, a known heating plant 23 which sends heated heat transfer fluid, via supply pipes 24 and return pipes 25 to a network of radiators 26.

When the valve 21 is closed and the two valves 19 and 20 are open, the heat transfer fluid coming from the network of radiators 26 can pass through both the heat exchanger 13 of the heat pump 12 and the heating plant 23 to have a double intake of calories, before returning to the radiators 26. If the central unit 23 is at rest, the heat pump 12 can provide heating only and when the heat pump 12 is at rest, the central unit 23 can also provide heating only. The circuit of the heat pump exchanger 13 can be isolated by closing the valves 19 and 20, the valve 21 then being open to allow the circuit to heating 22 to operate normally with the central 23. Circulators 27 and 28 can be mounted on the circuits of the exchanger 13 and heating 22 to accelerate the circulation of the heat transfer fluid.

The heat pump 12 preferably comprises two modular elements 47, 48 either mountable in a two-part arrangement (Figure 6) or assembled in a compact arrangement, in a single block (Figure 5).

The modular element 47 comprises the compressor 2 and the exchanger 13, mounted on a thermally insulating base 34 and hermetically closed by a thermally insulating bell 43. The exchanger 13 is preferably arranged around the compressor 2 and applied against its carcass. According to this structure, all the heat coming from the mechanical work of the motor-compressor 2 and from the compression of gaseous refrigerant is kept captive in the insulating enclosure defined by these base 34 and bell 43 to increase the potential for heat exchange with the fluid. coolant circulating in the heat exchanger 13.

The modular element 48 comprises the evaporator 5 forming a perforated tubular wall, protected at its external lateral surface by a protective grid or fins 42, a fan 30 arranged in the upper part of the evaporator 5 to generate a current of air 31, 32 which passes through this evaporator so as to promote an intense heat exchange between the air and the refrigerant stream in the evaporator 5. The evaporator 5 is heated by the air stream 31, 32. The refrigerant current in the evaporator 5 draws heat from this air to evaporate. The air is moved laterally along the arrows 31 and discharged axially upwards according to the arrows 32 or in the opposite direction to these arrows 31 and 32. The fan 30 is protected by a grid 39 which closes the upper end of the evaporator 5.

The lower end of this evaporator 5 rests on a bottom plate 37.

In an arrangement in two parts shown schematically and partially in Figure 6, the modular elements 47 and 48 distant from each other and forming part of the same refrigeration circuit 1 are interconnected in a known manner by pipes not shown, intended for the circulation of the refrigerant. The heat transfer fluid circuit 14 of the exchanger 13 of the modular element 47 is also connected in a known manner to the space heating circuit 22 by pipes not shown.

In a compact arrangement, in a single block or monobloc, the modular element 48 is fixed on top of the modular element 47 (FIG. 5). As in a two-part arrangement, the modular elements 47 and 48 are interconnected by pipes not shown in the common refrigeration circuit 1 while the heat transfer fluid circuit 14 of the heat exchanger 13 of the modular element 47 is connected to the heating circuit 22 by pipes not shown.

The connection of these pipes can be advantageously carried out with quick couplers of known type not shown.

The runoff which, entering the modular element 48 collects on the bottom plate 37 of the latter is evacuated by means of grooves not shown, formed in the upper surface of this plate 37. These grooves are oriented so as to bring the run-off water either to the peripheral edge of the bottom plate 37 to evacuate it by spillage or to a passage hole 41 opening into a discharge pipe 46 formed in the thickness of the vertical wall of the insulating bell 43 of the modular element 47.

The mechanical fixing connection between the modular elements 47 and 48 is obtained according to a known technique not described and with known fixing means not shown.

In an alternative embodiment shown schematically and partially in Figures 7 and 8, the evaporator 5 is heated by a stream of liquid. This heating liquid can be river, borehole or natural water, recovered waste water, or a heating liquid forming part of a closed underground circuit. The evaporator 5 and the heating liquid circuit constitutes a heat exchanger 44 produced in a similar manner to that of the heat exchanger 13 with, for example, pipes similar to those shown in FIG. 4, mounted coaxially with one another. the other. In this heat exchanger 44, the central pipe 51 intended for the circulation of the expanded refrigerant constitutes an evaporator circuit 51 while the external pipe 52, reserved for the flow of the heating liquid, constitutes a heating circuit 52.

In this variant embodiment, the heat pump 12 also comprises two modular elements 49, 50 which can be mounted in a two-part arrangement (FIG. 8) or which can be assembled in a compact arrangement, in a single block or in one piece (FIG. 7).

The modular element 49 comprises a structure similar or preferably identical to that of the modular element 47 in FIGS. 5 and 6, namely the motor-compressor 2, the heat exchanger 13, the insulating base 34 and the insulating bell 43.

The modular element 50 comprises a heat exchanger 44 mounted on a base plate 46 and protected by a bell 45. The protective bell 45 can have either an openwork and non-thermally insulating wall or a solid and thermally insulating wall. When the protective cover 45 is formed from a solid and thermally insulating wall, only the heating fluid constitutes the heat source for the refrigerant. When the protective cover 45 is perforated, the heat of the surrounding medium is added to the heating fluid to constitute the heat sources to the refrigerant of the evaporator 5 of the refrigeration circuit 1. Grooves not shown are also formed in the base plate 46 for discharging the runoff entering the modular element 50.

The heat pump 12 thus constructed is solid and can resist mechanical and weathering attack while achieving excellent performance in its operation, and remaining economical in its manufacture by the simplicity of its structure.

Claims (12)

1. Refrigeration circuit with motor-compressor, having in closed circuit mainly a condenser (3), an expansion valve (4), an evaporator (5) of the dry type, an anti-blow bottle and the motor-compressor (2), characterized in that it comprises in the interval between the regulator (4) and the motor-compressor (2), a connection line (7), a vertical composite suction manifold (8) and an evaporator (5), divided into several sections (5a, 5b, 5c) vertically spaced, mounted in parallel between this composite suction manifold (6) and this regulator (4), this vertical composite suction manifold (6) playing in addition to its role of evaporator manifold, the role of an anti-blow bottle and that of a pump-sprayer providing a return to the motor-compressor (2) and without damage to the latter, lubricant and liquid refrigerant trapped in the circuit. 2. Heat pump characterized in that it comprises a refrigeration circuit of claim l, wherein the condenser (3) forms with an independent circuit of heat transfer fluid (14), a heat exchanger (13). 3. Pump according to claim 2, characterized in that it comprises in the heat exchanger (13), an independent circuit of heat transfer fluid (14) constituted by a pipe (15) mounted coaxially in a pipe (16) forming the condenser (3). 4. Pump according to one of claims 2 and 3, characterized in that it comprises two modular elements (47, 48) mountable in an arrangement in two parts and assembled in a compact arrangement, in a single block of which the first ( 47) is provided with the motor compressor (2) and the heat exchanger (13), and the second (48) is provided with the evaporator (5) and a fan (30). 5. Pump according to one of claims 2 and 3, characterized in that it comprises two modular elements (49, 50) mountable in an arrangement in two parts and assembled in a compact arrangement, in a single block of which the first ( 49) is provided motor compressor (2) and heat exchanger (13), and the second (50) is provided with a heat exchanger (44) consisting of an evaporator circuit (-51) and a heater circuit (52). 6. Pump according to one of claims 4 and 5, characterized in that in the first modular element (47 or 49) the compressor (2) and the heat exchanger (13) are mounted on a thermally insulating base (34) and hermetically closed by a thermally insulating bell (43). 7. Pump according to one of claims 4, 5 and 6, characterized in that in the second modular element (48), the evaporator (5) forms a perforated tubular wall whose external lateral surface is protected by a grid or protective fins (42) and the upper and lower ends are respectively closed by a protective grid (39) and a bottom plate (37). 8. Pump according to claim 7, characterized in that in the second modular element (48) the bottom plate (37) closing the lower end of the evaporator (5) is provided in its surface with grooves drainage of runoff water. 9. Pump according to claim 8, characterized in that in the discharge of runoff entering the second modular element (48), it comprises in the first modular element (47) an evacuation pipe (46) formed in the thickness of the vertical wall of its insulating bell (43) and in the second element (48) at the end point of the evacuation grooves a hole (41) formed in the bottom plate (37) opening into this pipe evacuation (46) of the first modular element (47). 10. Pump according to one of claims 4, 5 and 6, characterized in that in the second modular element (50), the heat exchanger (44) is mounted on a base plate (46) and protected by a protective cover (45). 11. Pump according to claim 10, characterized in that in the second modular element (50) the protective cover (45) of the heat exchanger (44) has a perforated wall. 12. Pump according to claim 10, characterized in that in the second modular element (50) the protective cover (45) of the heat exchanger (44) has a solid and thermally insulating wall.

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