START-UP PROCEDURE FOR REFRIGERANT SYSTEMS HAVING MICROCHANNEL CONDENSER AND REHEAT CYCLE

Description

BACKGROUND OF THE INVENTION

[0001] Refrigerant systems utilize a refrigerant to condition a secondary fluid, such as air, delivered to a climate-controlled space. In a basic refrigerant system, the refrigerant is compressed in a compressor, and flows downstream to a condenser in a subcritical refrigerant cycle or to a gas cooler in a transcritical refrigerant cycle, where heat is typically rejected from the refrigerant to ambient environment, during heat transfer interaction with this ambient environment. Then refrigerant flows through an expansion device, where it is expanded to a lower pressure and temperature, and to an evaporator, where during heat transfer interaction with a secondary fluid (e.g., indoor air), the refrigerant is evaporated and typically superheated, while cooling and often dehumidifying this secondary fluid.

[0002] In recent years, much interest and design effort has been focused on the efficient operation of the heat exchangers (condenser and evaporator) of the refrigerant systems. One relatively recent advancement in heat exchanger technology is the development and application of parallel flow, or so-called microchannel or minichannel, heat exchangers (these two terms will be used interchangeably throughout the text), as the condensers and evaporators.

[0003] These heat exchangers are provided with a plurality of parallel heat exchange tubes, typically of a non-round shape, among which refrigerant is distributed and flown in a parallel manner. The heat exchange tubes are orientated generally substantially perpendicular to a refrigerant flow direction in the inlet, intermediate and outlet manifolds that are in flow communication with the heat exchange tubes. The heat exchange tubes typically have a multi-channel construction, with refrigerant distributed and flowing within these multiple channels in a parallel manner. Heat transfer fins are inter-disposed in between and rigidly attached to heat exchange tubes. The primary reasons for the employment of the parallel flow heat exchangers, which usually have aluminum furnace-brazed construction, are related to their superior performance, high degree of compactness, structural rigidity, lower weight, lower refrigerant charge and enhanced resistance to corrosion.

[0004] One concern with utilizing microchannel heat exchangers, also related to their advantage, is their low internal volume. Due to low internal volume, microchannel heat exchangers are more susceptible to refrigerant pressure variations due to instantaneous changes in refrigerant flow throughout the refrigerant circuit. Microchannel heat exchangers are also very sensitive to refrigerant charge amounts, with even a small amount of extra refrigerant charge in the system leading to higher than desirable discharge operating pressures and instantaneous pressure spikes. These problems are especially pronounced during start-ups. Nuisance interruptions of the refrigerant system operation can be a result of emergency shutdown by control software on a high pressure alarm or by mechanical safety, such as a high pressure switch, leading to complete inability to operate the refrigerant system, if a discharge pressure spike exceeded predetermined allowable safe limit (typically for a preset number of times). This consequently would results in a failure to keep a climate-controlled environment within desirable temperature and humidity ranges, leading to occupant discomfort and liability claims. Under certain circumstances, repeated starts and shutdowns in short periods of time can potentially lead to a compressor failure.

[0005] Another refrigerant cycle component is a reheat cycle utilizing primary refrigerant circulating throughout the main refrigerant circuit. In the reheat cycle, at least a portion of refrigerant passes through a reheat heat exchanger which is positioned in the path of air flowing across the evaporator. The reheat heat exchanger is typically positioned in the path of the air downstream of the evaporator. With a reheat cycle actuated, air can be cooled in the evaporator below normally desirable temperature, allowing for a greater amount of moisture removal from the air stream. The air then passes over the reheat heat exchanger and is heated back toward the target temperature. Typically, reheat cycles are provided with a refrigerant flow control device, such a three-way valve, that can selectively route at least a portion of refrigerant through the reheat heat exchanger when reheat is desired. The reheat cycle has not been operated at system start-up, in order to prevent high pressure spikes and nuisance refrigerant system shutdowns.
JP H05 26419 A discloses a channel from the high pressure side of the refrigerant system to the low pressure side of the refrigerant system, thereby bypassing the expansion device.

SUMMARY OF THE INVENTION

[0006] Viewed from a first aspect, the invention provides a refrigerant system comprising:

a compressor for delivering a compressed refrigerant to a condenser, refrigerant from said condenser passing through an expansion device, and from said expansion device through an evaporator, and from said evaporator being returned to said compressor;

a reheat cycle including a refrigerant flow control device for selectively routing at least a portion of refrigerant through a reheat heat exchanger, said refrigerant flow control device being positioned to route said at least portion of refrigerant through said reheat heat exchanger from a location between said compressor and said expansion device and downstream of said compressor, and said reheat heat exchanger being positioned in a path of air that has passed over said evaporator; and

a control for the system selectively actuating said switch to route at least a portion of refrigerant through said reheat heat exchanger at refrigerant system start-up;

characterised by said condenser being a microchannel heat exchanger;

wherein the refrigerant flow control device and the reheat heat exchanger are both located on the high pressure side of the refrigerant system, such that there is a larger combined internal volume on the high pressure side of the refrigerant system.

[0007] Viewed from a second aspect, the invention provides a method of operating a refrigerant system, comprising the steps of:

a) delivering a compressed refrigerant to a condenser, refrigerant from said condenser passing through an expansion device, and from said expansion device through an evaporator, and from said evaporator being returned to said compressor;

b) said condenser being a microchannel heat exchanger;

c) selectively routing at least a portion of refrigerant through a reheat heat exchanger from a location between said compressor and said expansion device and downstream of said compressor, and passing at least a portion of air over said reheat heat exchanger after the air has passed over said evaporator; and

d) selectively actuating a refrigerant flow control device to route said at least portion of refrigerant through said reheat heat exchanger at system start-up, wherein the refrigerant flow control device and the reheat heat exchanger are both located on the high pressure side of the refrigerant system, such that there is a larger combined internal volume on the high pressure side of the refrigerant system.

[0008] In a preferred arrangement, the reheat cycle may also be actuated at certain environmental and operating conditions, when high pressure spikes are expected to occur. Such conditions may include, for instance, high ambient temperatures, higher operating speeds of variable speed compressors and a higher number of active tandem compressors. These environmental and operating conditions may be pre-programmed and stored in the memory of the refrigerant system controller.

[0009] These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] 

Figure 1A shows a first embodiment schematic.

Figure 1B shows an alternative embodiment.

Figure 2A shows an exemplary microchannel heat exchanger.

Figure 2B is a cross-section through a portion of Figure 2A.

Figure 3 is a graph showing start-up utilizing the disclosed method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0011] A refrigerant system 20 is illustrated in Figure 1A and includes a compressor 22 delivering refrigerant into a discharge line heading to a condenser 24. The condenser 24 is a parallel flow heat exchanger, and according to the invention is a microchannel or minichannel heat exchanger. As mentioned above, these terms are used interchangeably here.

[0012] Heat is transferred in the condenser 24 from the refrigerant to a secondary fluid, such as ambient air. The high pressure, desuperheated, condensed and typically subcooled, refrigerant passes from the condenser 24 into an expansion device 38, where it is expanded to a lower pressure and temperature. Downstream of the expansion device 38, refrigerant flows through an evaporator 36 and back to the compressor 22. As known, the heat exchanger 24 operates as a condenser in subcritical applications and as a gas cooler in transcritical applications. Nevertheless, although both applications are within the scope of the invention, the heat exchanger 24 will be referred throughout the text as a condenser.

[0013] A reheat cycle is incorporated into the refrigerant system 20. As known, a refrigerant flow control device such as a three-way valve 30 selectively routes at least a portion of refrigerant downstream of the condenser 24 and through a reheat heat exchanger 32. An air-moving device such as a fan 34 blows air over an evaporator 36, and over the reheat heat exchanger 32. That is, the reheat heat exchanger 32 is positioned indoors, along with the evaporator 36, and downstream, with respect to the air flow, of the evaporator 36. As mentioned above, essentially, the reheat cycle is selectively actuated by opening (fully or partially) the three-way valve 30 to direct at least a portion of refrigerant through the reheat heat exchanger 32 when dehumidification in a climate-controlled environment X is desired. Under such circumstances, the refrigerant system is controlled such that the evaporator 36 cools the air to a temperature below that is desired in the environment to be conditioned X, which allows removing an additional amount of moisture from the air to be delivered to the conditioned environment X. As the air passes over the reheat heat exchanger 32, it is reheated toward the target temperature. As a result, temperature and humidity control are achieved in the climate-controlled environment X.

[0014] Downstream of the reheat heat exchanger 32, there is an optional check valve 40. Further, as shown, a condenser bypass line 26 selectively bypasses at least a portion of refrigerant around the condenser 24 and includes a refrigerant flow control device such as a valve 28. This allows for achieving variable dehumidification capability, or variable sensible heat ratios. The valve 28 can be adjustable (through modulation or pulsation) or of an on/off type.

[0015] Figure 1B shows an alternative embodiment wherein the reheat cycle three-way valve 42 is positioned upstream of the condenser 24 and delivers at least a portion of refrigerant through a reheat refrigerant line 44 to a reheat heat exchanger (not shown). For purposes of this application, the exact location of the three-way valve 42 and the reheat heat exchanger 32 is not critical, provided they are both located on the high pressure side of the refrigerant system 20. Also, as known, the three-way valves 30 and 42 can be replaced by a pair of conventional valves performing identical refrigerant routing function.

[0016] As shown in Figure 2A, an inlet line 146 downstream of the compressor 22 delivers refrigerant into a first bank of parallel heat exchange tubes 148, and then across the condenser core to a first chamber of an intermediate manifold structure 133. From the intermediate manifold structure 133, the refrigerant passes back through a second bank of parallel heat exchange tubes 150 to an intermediate chamber in the manifold 147. Refrigerant then passes through yet another bank of parallel heat exchange tubes 152, returning to the intermediate manifold 133. From the intermediate manifold 133, the refrigerant passes through another bank of heat exchange tubes 154 back to the manifold 147, and an outlet refrigerant line. Of course, this is simply one illustrated embodiment. It should be noted that, in practice, there may be more or less refrigerant passes than the four illustrated passes 148, 150, 152, and 154. Further, it should be understood that, although for simplicity purposes, each refrigerant pass is represented by a single heat exchange tube, typically there are many heat exchange tubes within each pass amongst which refrigerant is distributed while flowing within the pass. In condenser applications, a number of the heat exchange tubes within each bank may decrease in a downstream direction, with respect to refrigerant flow. For instance, there could be 12 heat exchange tubes in the first bank, 8 heat exchange tubes in the second bank, 5 heat exchange tubes in a third bank and only 2 heat exchange tubes in the last forth bank. Separator plates 143 are placed within the manifolds 133 and 147 to separate the chambers positioned within the same manifold structure.

[0017] As shown in Figure 2B, the heat exchange tubes within the tube banks 148, 150, 152, and 154 may consist of a plurality of parallel channels 100 separated by walls 101. The Figure 2B is a cross-sectional view of the heat exchange tubes shown in Figure 2A. The channels 100 allow for enhanced heat transfer characteristics and assist in improved structural rigidity of the heat exchanger. The cross-section of the channels 100 may take different forms, and although illustrated as a rectangular in Figure 2B, may be, for instance, of triangular, trapezoidal, oval or circular configurations. The size of the channels 100 in a microchannel heat exchanger is quite small. As disclosed, the channels could have a hydraulic diameter of less than or equal to 5 mm, and more narrowly, less than or equal to 3 mm. Notably, the use of "hydraulic diameter" does not imply the channels are circular.

[0018] As mentioned above, when microchannel heat exchangers are utilized as condensers, pressure spikes which can be particularly observed at the refrigerant system start-up, can provide a challenge to a refrigerant system designer. One concern with microchannel heat exchangers is that their internal volume is relatively small, and thus they are particularly susceptible to pressure spikes and extremely sensitive to refrigerant charge amounts. Although pressure spikes are particularly pronounced at refrigerant system start-up, they can be also observed at changes of operating conditions such as, for instance, a sharp increase of the compressor speed or activating a larger number of tandem compressors, in order to satisfy thermal load demands in the conditioned space X.

[0019] In this invention, the reheat circuit is actuated at refrigerant system start-up. Now, when the refrigerant is passing through both the condenser 24, and through the reheat heat exchanger 32, there is a larger combined internal volume on a high pressure side of the refrigerant system, and the amplitude of the pressure spike is thus reduced. In some instances, all of the refrigerant could pass through the reheat heat exchanger 32.

[0020] As shown in Figure 3, with a conventional start-up S, and without the reheat circuit being actuated, a pressure spike can be relatively high, and may exceed the safety limit Y. With the present application, and as shown at Z in Figure 3, the amplitude of the pressure spike is greatly reduced, due to the combined internal volume of the heat exchangers 24 and 32. In this manner, the pressure spike may well be below the safety limit Y, and nuisance shutdowns, caused by control software operating on a high pressure alarm or by mechanical safety, such as a high pressure switch, can be avoided. This provides uninterrupted control of temperature and humidity within the desired ranges and occupant comfort in the climate-controlled environment. Furthermore, repeated starts and shutdowns of the refrigerant system in short periods of time will be avoided, leading to improved compressor reliability and temperature/humidity variation reduction in the conditioned space.

[0021] The reheat heat exchanger 32 can be any type of a heat exchanger, including standard heat exchangers or a microchannel heat exchanger.

[0022] A control 110 for the refrigerant system may be of any appropriate electronic control type, as is known in the art. The control would typically control all system components, and not only the three-way valve 30 that can be adjustable (through modulation or pulsation) or of an on/off type. The control 110 can actuate the reheat cycle at certain environmental and operating conditions, when high pressure spikes are likely to occur. Such conditions may include, for instance, high ambient temperatures, higher operating speeds of variable speed compressors and a higher number of active tandem compressors. These environmental and operating conditions may be pre-programmed and stored in the memory of the refrigerant system control 110. Further, under some environment and operating conditions, it may be that there is less likelihood of a pressure spike at system start-up. Thus, the control may be programmed to not actuate the reheat cycle in these instances.

[0023] In addition, after some period of time following refrigerant system start-up, the three-way valve 30 is deactivated to block flow of refrigerant through the reheat heat exchanger 32, unless dehumidification mode of operation is desired. This period of time can be on the order of 15 seconds to 3 minutes.

Claims

1. A refrigerant system (20) comprising:

a compressor (22) for delivering a compressed refrigerant to a condenser (24), refrigerant from said condenser passing through an expansion device (38), and from said expansion device through an evaporator (36), and from said evaporator being returned to said compressor;

a reheat cycle including a refrigerant flow control device (30, 42) for selectively routing at least a portion of refrigerant through a reheat heat exchanger (32), said refrigerant flow control device being positioned to route said at least portion of refrigerant through said reheat heat exchanger from a location between said compressor and said expansion device and downstream of said compressor, and said reheat heat exchanger being positioned in a path of air that has passed over said evaporator; and

a control for the system (110) selectively actuating said switch (30, 42) to route at least a portion of refrigerant through said reheat heat exchanger at refrigerant system start-up;

characterised by:

said condenser being a microchannel heat exchanger;

wherein the refrigerant flow control device (30, 42) and the reheat heat exchanger (32) are both located on the high pressure side of the refrigerant system (20),

such that there is a larger combined internal volume on the high pressure side of the refrigerant system.

2. The refrigerant system as set forth in claim 1, wherein said control is also routing said at least a portion of refrigerant through said reheat heat exchanger when at least one of a start-up, compressor speed change, tandem compressor activation or high ambient temperature conditions occur.

3. The refrigerant system as set forth in claim 2, wherein said conditions are programmed in the control to identify when to selectively actuate said refrigerant flow control device to route refrigerant through said reheat heat exchanger.

4. The refrigerant system as set forth in claim 1, wherein a bypass (26) is provided around said condenser to selectively bypass at least a portion of refrigerant around said condenser.

5. The refrigerant system as set forth in claim 1, wherein said refrigerant flow control device is actuated to selectively allow for refrigerant flow through the reheat heat exchanger for at least a predetermined period of time after said condition is identified.

6. The refrigerant system as set forth in claim 5, wherein said predetermined period of time is preferably from 15 seconds to 3 minutes.

7. The refrigerant system as set forth in claim 1, wherein said refrigerant flow control device is one of adjustable type through modulation or pulsation or of an on/off type.

8. The refrigerant system as set forth in claim 1, wherein said microchannel heat exchanger includes a plurality of heat exchange tube each having a plurality of parallel refrigerant channels.

9. The refrigerant system as set forth in claim 8, wherein said microchannel heat exchanger having flow channels with a hydraulic diameter less than or equal to 5 mm.

10. The refrigerant system as set forth in claim 1, wherein all of the refrigerant passes through said reheat heat exchanger.

11. A method of operating a refrigerant system (20) comprising the steps of:

a) delivering a compressed refrigerant to a condenser (24), refrigerant from said condenser passing through an expansion device (38), and from said expansion device through an evaporator (36), and from said evaporator being returned to said compressor;

b) said condenser being a microchannel heat exchanger;

c) selectively routing at least a portion of refrigerant through a reheat heat exchanger (32) from a location between said compressor and said expansion device and downstream of said compressor, and passing at least a portion of air over said reheat heat exchanger after the air has passed over said evaporator; and

d) selectively actuating a refrigerant flow control device (30, 42) to route said at least portion of refrigerant through said reheat heat exchanger at system start-up, wherein the refrigerant flow control device (30, 42) and the reheat heat exchanger (32) are both located on the high pressure side of the refrigerant system (20), such that there is a larger combined internal volume on the high pressure side of the refrigerant system.

12. The method as set forth in claim 11, further comprising the step of routing said at least a portion of refrigerant through said reheat heat exchanger when at least one of a start-up, compressor speed change, tandem compressor activation or high ambient temperature occurs.

13. The method as set forth in claim 11, further comprising the step of selectively allowing refrigerant flow through the reheat heat exchanger for at least a predetermined period of time after refrigerant system start-up.

14. The method as set forth in claim 11, wherein all of the refrigerant passes through said reheat heat exchanger.

Ansprüche

1. Kältemittelsystem (20), das Folgendes umfasst:

einen Verdichter (22) zum Liefern eines verdichteten Kältemittels an einen Kondensator (24), wobei das Kältemittel von dem Kondensator durch eine Expansionsvorrichtung (38) läuft, und von der Expansionsvorrichtung durch einen Verdampfer (36), und wobei es von dem Verdampfer zu dem Verdichter zurückgeführt wird;

einen Nachheizzyklus, der eine Kältemittelflusssteuervorrichtung (30, 42) zum selektiven Leiten von wenigstens einem Anteil des Kältemittels durch einen Nachheiz-Wärmetauscher (32) einschließt, wobei die Kältemittelflusssteuervorrichtung positioniert ist, um den wenigstens einen Anteil des Kältemittels durch den Nachheiz-Wärmetauscher von einer Stelle zwischen dem Verdichter und der Expansionsvorrichtung und stromabwärts des Verdichters zu leiten, und wobei der Nachheiz-Wärmetauscher in einem Weg von Luft positioniert ist, die über den Verdampfer gelaufen ist; und
eine Steuerung für das System (110), die selektiv den Schalter (30, 42) betätigt, um beim Starten des Kältemittelsystems wenigstens einen Anteil des Kältemittels durch den Nachheiz-Wärmetauscher zu leiten;

dadurch gekennzeichnet, dass:

der Kondensator ein Mikrokanal-Wärmetauscher ist;

wobei die Kältemittelflusssteuervorrichtung (30, 42) und der Nachheiz-Wärmetauscher (32) sich beide auf der Hochdruckseite des Kältemittelsystems (20) befinden,

sodass es ein größeres kombiniertes Innenvolumen auf der Hochdruckseite des Kältemittelsystems gibt.

2. Kältemittelsystem nach Anspruch 1, wobei die Steuerung den wenigstens einen Anteil des Kältemittels ebenfalls durch den Nachheiz-Wärmetauscher leitet, wenn wenigstens eine Bedingung auftritt von einem Starten, einer Verdichtergeschwindigkeitsänderung, einer Aktivierung eines Tandemverdichters oder einer hohen Umgebungstemperatur.

3. Kältemittelsystem nach Anspruch 2, wobei die Bedingungen in die Steuerung einprogrammiert sind, um zu identifizieren, wann die Kältemittelflusssteuervorrichtung selektiv betätigt werden soll, um Kältemittel durch den Nachheiz-Wärmetauscher zu leiten.

4. Kältemittelsystem nach Anspruch 1, wobei ein Bypass (26) um den Verdichter bereitgestellt ist, um selektiv wenigstens einen Anteil des Kältemittels um den Verdichter herum zu führen.

5. Kältemittelsystem nach Anspruch 1, wobei die Kältemittelflusssteuervorrichtung betätigt wird, um selektiv einen Kältemittelfluss durch den Nachheiz-Wärmetauscher für wenigstens einen vorbestimmten Zeitraum nach dem Identifizieren der Bedingung zu erlauben.

6. Kältemittelsystem nach Anspruch 5, wobei der vorbestimmte Zeitraum vorzugsweise 15 Sekunden bis 3 Minuten beträgt.

7. Kältemittelsystem nach Anspruch 1, wobei die Kältemittelflusssteuervorrichtung eine ist von einer durch Modulieren oder Pulsieren anpassbaren Art oder einer An/Aus-Art.

8. Kältemittelsystem nach Anspruch 1, wobei der Mikrokanal-Wärmetauscher eine Vielzahl von Wärmetauschrohren einschließt, wobei jedes eine Vielzahl von parallelen Kältemittelkanälen ausweist.

9. Kältemittelsystem nach Anspruch 8, wobei der Mikrokanal-Wärmetauscher Durchflusskanäle mit einem hydraulischen Durchmesser von weniger oder gleich 5 mm aufweist.

10. Kältemittelsystem nach Anspruch 1, wobei das gesamte Kältemittel den Nachheiz-Wärmetauscher durchläuft.

11. Verfahren zum Bedienen eines Kältemittelsystems (20), das folgende Schritte umfasst:

a) Liefern eines verdichteten Kältemittels an einen Kondensator (24), wobei das Kältemittel von dem Kondensator durch eine Expansionsvorrichtung (38) läuft, und von der Expansionsvorrichtung durch einen Verdampfer (36), und wobei es von dem Verdampfer zu dem Verdichter zurückgeführt wird;

b) wobei der Kondensator ein Mikrokanal-Wärmetauscher ist;

c) selektives Leiten von wenigstens einem Anteil des Kältemittels durch einen Nachheiz-Wärmetauscher (32) von einer Stelle zwischen dem Verdichter und der Expansionsvorrichtung und stromabwärts des Verdichters, und ein Laufen von wenigstens einem Anteil von Luft über den Nachheiz-Wärmetauscher, nachdem die Luft über den Verdampfer gelaufen ist; und

d) selektives Betätigen einer Kältemittelflusssteuervorrichtung (30, 42), um den wenigstens einen Anteil des Kältemittels beim Starten des Systems durch den Nachheiz-Wärmetauscher zu leiten, wobei die Kältemittelflusssteuervorrichtung (30, 42) und der Nachheiz-Wärmetauscher (32) sich beide auf der Hochdruckseite des Kältemittelsystems (20) befinden, sodass es ein größeres kombiniertes Innenvolumen auf der Hochdruckseite des Kältemittelsystems gibt.

12. Verfahren nach Anspruch 11, ferner umfassend den Schritt des Leitens des wenigstens einen Anteils von Kältemittel durch den Nachheiz-Wärmetauscher, wenn wenigstens eines von einem Starten, einer Verdichtergeschwindigkeitsänderung, einer Aktivierung eines Tandemverdichters oder einer hohen Umgebungstemperatur auftritt.

13. Verfahren nach Anspruch 11, ferner umfassend den Schritt des selektiven Erlaubens eines Kältemittelflusses durch den Nachheiz-Wärmetauscher für wenigstens einen vorbestimmten Zeitraum nach dem Starten des Kältemittelsystems.

14. Verfahren nach Anspruch 11, wobei das gesamte Kältemittel durch den Nachheiz-Wärmetauscher läuft.

Revendications

1. Système frigorifique (20) comprenant :

un compresseur (22) pour délivrer un agent frigorigène comprimé à un condensateur (24), l'agent frigorigène en provenance dudit condensateur passant à travers un dispositif de détente (38), et à partir dudit dispositif de détente à travers un évaporateur (36), et étant retourné à partir dudit évaporateur vers ledit compresseur ;

un cycle de réchauffage incluant un dispositif de régulation d'écoulement d'agent frigorigène (30, 42) pour acheminer sélectivement au moins une partie de l'agent frigorigène à travers un échangeur de chaleur de réchauffage (32), ledit dispositif de régulation d'écoulement d'agent frigorigène étant positionné pour acheminer ladite au moins une partie d'agent frigorigène à travers ledit échangeur de chaleur de réchauffage depuis un emplacement entre ledit compresseur et ledit dispositif de détente et en aval dudit compresseur, et ledit échangeur de chaleur de réchauffage étant positionné dans un trajet de l'air qui est passé au-dessus dudit évaporateur ; et

une commande pour le système (110) actionnant sélectivement ledit interrupteur (30, 42) pour acheminer au moins une partie d'agent frigorigène à travers ledit échangeur de chaleur de réchauffage au démarrage du système frigorifique ;

caractérisé en ce que :

ledit condensateur est un échangeur de chaleur à micro-canaux ; dans lequel le dispositif de régulation d'écoulement d'agent frigorigène (30, 42) et l'échangeur de chaleur de réchauffage (32) sont tous deux situés sur le côté haute pression du système frigorifique (20),

de telle sorte qu'il existe un volume interne combiné plus grand sur le côté haute pression du système frigorifique.

2. Système frigorifique selon la revendication 1, dans lequel ladite commande achemine également ladite au moins une partie d'agent frigorigène à travers ledit échangeur de chaleur de réchauffage lorsque survient au moins l'une de conditions de démarrage, de changement de vitesse de compresseur, d'activation de compresseurs en tandem ou de température ambiante élevée.

3. Système frigorifique selon la revendication 2, dans lequel lesdites conditions sont programmées dans la commande pour identifier le moment où actionner sélectivement ledit dispositif de régulation d'écoulement d'agent frigorigène pour acheminer l'agent frigorigène à travers ledit échangeur de chaleur de réchauffage.

4. Système frigorifique selon la revendication 1, dans lequel une dérivation (26) est prévue autour dudit condensateur pour dériver sélectivement au moins une partie de l'agent frigorigène autour dudit condensateur.

5. Système frigorifique selon la revendication 1, dans lequel ledit dispositif de régulation d'écoulement d'agent frigorigène est actionné pour permettre sélectivement l'écoulement d'agent frigorigène à travers l'échangeur de chaleur de réchauffage pendant au moins une période de temps prédéterminée une fois ladite condition identifiée.

6. Système frigorifique selon la revendication 5, dans lequel ladite période de temps prédéterminée est de préférence de 15 secondes à 3 minutes.

7. Système frigorifique selon la revendication 1, dans lequel ledit dispositif de commande d'écoulement d'agent frigorigène est l'un d'un type ajustable par modulation ou impulsion ou d'un type marche/arrêt.

8. Système frigorifique selon la revendication 1, dans lequel ledit échangeur de chaleur à micro-canaux inclut une pluralité de tubes d'échange de chaleur ayant chacun une pluralité de canaux d'agent frigorigène parallèles.

9. Système frigorifique selon la revendication 8, dans lequel ledit échangeur de chaleur à micro-canaux possède des canaux d'écoulement ayant un diamètre hydraulique inférieur ou égal à 5 mm.

10. Système frigorifique selon la revendication 1, dans lequel l'ensemble de l'agent frigorigène passe à travers ledit échangeur de chaleur de réchauffage.

11. Procédé de fonctionnement d'un système frigorifique (20) comprenant les étapes suivantes :

a) fourniture d'un agent frigorigène comprimé à un condensateur (24), l'agent frigorigène en provenance dudit condensateur passant à travers un dispositif de détente (38), et à partir dudit dispositif de détente à travers un évaporateur (36), et étant retourné à partir dudit évaporateur vers ledit compresseur ;

b) ledit condensateur étant un échangeur de chaleur à micro-canaux ;

c) acheminement sélectif d'au moins une partie de l'agent frigorigène à travers un échangeur de chaleur de réchauffage (32) depuis un emplacement entre ledit compresseur et ledit dispositif de détente et en aval dudit compresseur, et passage d'au moins une partie de l'air au-dessus dudit échangeur de chaleur de réchauffage une fois que l'air est passé au-dessus dudit évaporateur ; et

d) actionnement sélectif d'un dispositif de régulation d'écoulement d'agent frigorigène (30, 42) pour acheminer ladite au moins une partie d'agent frigorigène à travers ledit échangeur de chaleur de réchauffage au démarrage du système, dans lequel le dispositif de régulation d'écoulement d'agent frigorigène (30, 42) et l'échangeur de chaleur de réchauffage (32) sont tous deux situés sur le côté haute pression du système frigorifique (20), de telle sorte qu'il existe un volume interne combiné plus grand sur le côté haute pression du système frigorifique.

12. Procédé selon la revendication 11, comprenant en outre l'étape d'acheminement de ladite au moins une partie d'agent frigorigène à travers ledit échangeur de chaleur de réchauffage lorsque survient au moins l'un d'un démarrage, d'un changement de vitesse de compresseur, d'une activation de compresseurs en tandem ou d'une température ambiante élevée.

13. Procédé selon la revendication 11, comprenant en outre l'étape de permission sélective d'écoulement d'agent frigorigène à travers l'échangeur de chaleur de réchauffage pendant au moins une période de temps prédéterminée après démarrage du système frigorifique.

14. Procédé selon la revendication 11, dans lequel l'ensemble de l'agent frigorigène passe à travers ledit échangeur de chaleur de réchauffage.

Drawing