REFRIGERATED CASE

Description

[0001] The invention relates to a refrigerated case comprising a plate fin heat exchanger and a method for using said refrigerated case.

[0002] A number of refrigerated case configurations have the compressor and heat rejection heat exchanger in the base of the case below the refrigerated compartment (e.g., an open-front case, a door- front case, an open-top case, and the like). To cool the heat rejection heat exchanger, a fan drives an airflow along a flowpath through the heat rejection heat exchanger. For ease of reference, the heat rejection heat exchanger will be referred to as a "condenser" which is intended to comprehend both true condensers and gas coolers. When operated in the normal (cooling) mode of operation, the fan drives the airflow along the flowpath. Typically, the airflow across the condenser is front-to-back with relatively cool room air entering a grille at the front of the base and passing essentially straight through and exiting the rear of the base. The proximity of the base to the floor causes this airflow to be particularly dirty (e.g., dusty). There is a tendency for such contaminants to accumulate on the condenser and decrease its performance/efficiency. The decrease can include a combination of insulating the condenser from the airflow and blocking the airflow. This contamination or fouling occurs not merely on the tube sections of the condenser but also, and especially, on fins. An exemplary fin heat exchanger is a round tube plate fin (RTPF) heat exchanger wherein there is typically a lateral array of plates extending vertically and front-to-back. Each of the tube sections extends through and is in thermal contact with the plates.

[0003] As fouling accumulates, periodically the fan may be reversed to reverse the airflow to backflush the condenser. This may, for example, be done during the defrost cycle. However, backflushing is not fully effective and, from time to time, there must be a manual cleaning (e.g., vacuuming/brushing).

[0004] To partially address such fouling problems, anti-fouling coatings have been proposed.

[0005] JP 8-189752 and FR 2724873 disclose plate fin heat exchangers of the type described in the preamble of claim 1.

[0006] US 2902264 A relates to a radiator core to be installed in tractor type vehicles and GB 590806 A relates to heat exchanging devices employed with liquid heaters.JPS6032682U shows a further example of a heat exchanger and JP2000123238A discloses a refrigerated case according to the preamble of claim 1.

[0007] The invention provides a refrigerated case comprising a plate fin heat exchanger comprising: a plurality of tube sections extending across an air flowpath, including a first group of sections forming a leading group of tube sections; and means for shielding portions of the fins ahead of the leading group against debris accumulation; characterised in that the means comprises a plurality of bars immediately in front of and respectively associated with individual ones of the tube sections of the leading group, at the same height thereas, and each bar extending no more than 15% of the tube diameter above or below the associated tube sections, when the heat exchanger is in use with vertically arranged tube sections, and not out of phase therewith; and wherein the bars have trailing ends, and wherein the trailing ends have a spacing ahead of the associated ones of the tube sections. The bars have a v-shaped cross section and have trailing ends having a spacing ahead of the fins that is up to 30mm.

[0008] A method for using the refrigerated case is also claimed.

[0009] Preferred embodiments will now be described by way of example only and with reference to the accompanying drawings, in which:

FIG. 1 is a simplified view of a refrigerated case.

FIG. 2 is a simplified vertical front-to-back sectional view of the case of FIG. 1.

FIG. 3 is a schematic view of a refrigeration system of the case of FIG. 1.

FIG. 4 is a top side view of a heat exchanger.

FIG. 5 is a top front view of the heat exchanger of FIG. 4.

FIG. 6 is a top view of the heat exchanger of FIG. 4.

FIG. 7 is a front cutaway view of the heat exchanger of FIG. 6, taken along line 7-7.

FIG. 8 is a first side view of the heat exchanger of FIG. 6.

FIG. 9 is a second side view of the heat exchanger of FIG. 6.

FIG. 10 is a side schematic view of the heat exchanger of FIG. 6 in a cooling mode.

FIG. 11 is a side schematic view of the heat exchanger of FIG. 6 in a cleaning mode.

FIG. 12 is a side schematic view of a second heat exchanger.

FIG. 13 is a side schematic view of a third heat exchanger.

FIG. 14 is a partial top view of a fourth heat exchanger

[0010] Like reference numbers and designations in the various drawings indicate like elements.

[0011] FIGS. 1 and 2 show a refrigerated case 20 having a body 22 at least partially enclosing a refrigerated compartment (interior) 24. The exemplary case/body is an open- front case having a left wall 26 at a left side 28, a right wall 30 at a right side 32, a top panel (wall) 34 at a top 36, a base 38 at a bottom 40, and a rear (back) panel 42 at a back (rear end) 44. An opening 46 extends at least partially along a front of 48 of the case. In the exemplary case, a vertical array of shelves 50 is positioned within the compartment 24.

[0012] The exemplary case 20 includes a refrigeration system 60 (FIG. 3). The refrigeration system comprises a compressor 62 along a refrigerant flowpath 64. The compressor has an inlet (suction port) 66 and an outlet (discharge port) 68. The refrigeration system includes a first refrigerant-air heat exchanger 70 and a second refrigerant-air heat exchanger 72. An expansion device 74 may be along the refrigerant fiowpath 64 between the heat exchangers 70 and 72 opposite the compressor. Fans 80 and 82 may respectively drive airflows 84 and 86 across the heat exchangers 70 and 72.

[0013] In a cooling mode of operation, refrigerant compressed by the compressor exits the outlet 68 and proceeds to the first heat exchanger 70 which acts as a condenser or gas cooler (heating the air flow 84 to reduce the temperature of refrigerant as it flows through the first heat exchanger 70). Refrigerant proceeds downstream along the refrigerant fiowpath 64 to the expansion device 74 where it is expanded and its temperature further reduced. The cold refrigerant enters the second heat exchanger 72 (which acts as an evaporator, absorbing heat from the airflow 86 and heating the refrigerant as it flows through the second heat exchanger 72). Refrigerant discharged from the second heat exchanger 72 returns to the compressor inlet 66. Other details, including accumulators, valves, and sensors may be present but are not shown for ease of illustration.

[0014] FIG. 2 shows further details of a base air fiowpath 98 and a recirculating cabinet/case air fiowpath 100 and exemplary positioning of components of the refrigeration system 60. In the exemplary case 20, the compressor 62 and first heat exchanger 70 are positioned within a compartment of the base 38. A rear duct is located between the rear wall 42 and the compartment 24. The rear duct extends from a base duct at a lower end of the compartment which has an inlet 108 at a lower end of the front opening. The second heat exchanger 72 is positioned within the base outlet. The rear duct feeds a top duct 110 which has an outlet 112. The flow 86 produces a discharge flow 114 from the outlet which may initiate/form an air curtain along the opening 46. Additional branching flows 115 may branch off the flow 86 and pass into the compartment 24. At least a portion of the flow 114 and any branching flows returns to the inlet 108 as an inlet flow 116. In the exemplary embodiment, the fan 82 is positioned near the front (upstream) end of base duct.

[0015] In a cooling mode, moisture in the inlet flow 116 may freeze on the heat exchanger 72 and may produce a frost accumulation which may lead to a blockage. Accordingly, a defrost mode may be initiated. Exemplary defrost may be via a heating element (e.g., an electric resistance element) and/or via directing hot refrigerant to the heat exchanger 72 (instead of cold refrigerant). The defrost operation melts the frost which may flow downward as a flow (e.g., of droplets) and reach a drain. An exemplary drain is formed proximate a lower end of the rear duct. The drain may include a trap (e.g., a conventional J or S trap or a more complex trap such as that shown in JP2004353909). The drain, in turn, may discharge water as one or more flows into an evaporation vessel or a drainline.

[0016] FIGS. 4 and 5 show an exemplary heat rejection heat exchanger 70 (hereinafter generically "condenser" which includes both true condensers and gas coolers). The exemplary condenser 70 is an RTPF condenser having a plurality of sections of tube (e.g., an array) spanning first and second endplates 150 and 152. At the endplates, various of the tube sections are coupled to each other (e.g., via bends or U-shaped connectors to create the refrigerant circuit/flowpath through the condenser). The exemplary condenser has a plurality of rows of tube sections (an exemplary four rows shown extending from a leading group or row 154 (shown oriented horizontally and arrayed vertically) to a trailing row 156 with two intermediate rows 158 and 160). The leading and trailing direction is defined relative to the cooling mode direction of the airflow 84 along the flowpath 98.

[0017] FIG. 6 also shows the array of individual fin plates 162 extending between the endplates 150 and 152. The plates, thus, have leading edges 164 and trailing edges 166. The exemplary fan 80 is normally a pull-through fan drawing the airflow 84 across the tube array. As heretofore described, the condenser may be otherwise a conventional condenser. The condenser may, however, have added to it a shield 170 which helps mitigate fouling problems. Such a shield may also be used with other heat exchanger constructions such as finned-tube or other non-plate finned constructions. The shield may alternatively be defined as part of the condenser or as a separate element. It has been observed that fouling is particularly significant along/near the leading edges of the plates 162. In the backflushing mode, it has been observed that the backflushing is relatively ineffective at removing fouling from the portions of the plates immediately forward (upstream in the cooling mode direction of the airflow 84 but downstream in the backflush mode direction) of the tube sections of the leading row 154. These areas may be referred to as the "wind shadow" of such tube sections in that the tube sections block the airflow so that relatively high velocity airflow clears the fins between the tube sections but the relatively lower velocity in the shadow is less effective at cleaning. The lack of uniform cleaning caused by this effect has several consequences. First, there is a slight initial loss of efficiency relative to a fully clean condenser. Also, however, the still-fouled areas in the shadow can act as catalysts/seeds, increasing the rapidity by which the clean areas foul. The shield 170 serves as means for reducing fouling in the wind shadow areas of the leading row of tubes (relative to accumulation in the inter-tube spaces between such areas). This compensates for the relative inability of backflushing to access/clean the wind shadow areas. The exemplary shield 170 does this by serving as a means for preferentially shielding the leading group of tube sections (and the wind shadow areas of the fins) in the cooling mode. Specifically, the airflow is directed away from the front of the tube sections and toward the inter-tube spaces. The direction is "preferential" in that it is towards certain areas (the "preferred" inter-tube areas) relative to the wind shadow areas. Thus, the leading tubes and their wind shadow areas are preferentially shielded.

[0018] FIG. 10 shows the shield 170 as having an array of bars 180 directly and immediately (no intervening structures) in front of and respectively associated with individual ones of the tube sections of the leading group 154. The bars 180 tend to block contaminants from accumulating in the wind shadow areas 182 while relatively freely allowing contaminants/fouling 184 to reach the inter-tube areas 186 between the wind shadow areas 182.

[0019] FIG. 11 shows the backflushing ejecting the fouling. According to the present invention, the bars 180 are formed as V-sectioned members having a leading end 190 at the vertex of the V and a trailing end 192 formed by the opposite ends of the legs of the V. The exemplary bar height H is close to the tube height (diameter D for a round tube). According to the present invention, the trailing ends 192 have a spacing S₁ ahead of the associated tubes and S₂ ahead of the fins. According to the present invention, S₂ is up to about 30mm (more narrowly, 2-10mm, or 3-6mm, or about 5mm). As discussed below, this dimension can technically become negative if the fins are recessed into the bars. Exemplary H is 80-120% of D (e.g., about 1.0 x D). Exemplary tube outer diameter OD is 7.2mm or 3/8 of an inch. According to the present invention, the bars are registered with the associated tube sections (i.e. at the same height and not out-of-phase). According to the present invention, the bars extend no more than 15% of D above or below the associated tubes, more narrowly, no more than 10% or 5% above or below.

[0020] Exemplary bar materials are plastic (such as polyethylene, polypropylene, acrylonitrile styrene acrylate (ASA), or ABS-PMMA) or metal (e.g., aluminum or lacquered steel). It is desirable that the surface of the bar material be relatively smooth so as to hinder dust accumulation on the bars. The bars may be secured in any of several ways. FIGS. 4 and 5 show the bars mounted to endplates which are secured as extensions of the existing condenser endplates (sideplates). However, in a production environment this might be made by merely using larger condenser endplates. FIG. 12 shows the bars mounted on a structure which is secured to the bottom of the base compartment ahead of the condenser. FIG. 3 shows the bars (or a frame structure holding the bars) registered to the condenser via brackets 200 to engage one or more of the leading tube sections. FIG. 14 shows recesses 220 in the bars which accommodate the fins (and thus the negative value of S₂ previously mentioned).

[0021] In operation, there may be several advantages to such a system. The relative cleanliness of the condenser post-backflushing may yield relatively higher efficiencies post back-flushing. Reduction in the catalyst/seed effect may delay further loss of efficiency. Most significantly, the frequency of needed manual cleaning may be reduced.

[0022] The system may be implemented with conventional manufacturing techniques and materials (e.g., brazing or welding metal bars to associated endplates or gripping or gluing metal or plastic bars). The bar material may be stock angle material (e.g., right angle). Use parameters may be essentially unchanged. For example, the backflushing may still occur in the defrost mode (e.g., under fully automated or semi-automated control). The manual cleaning may still be performed via vacuuming. Depending upon the situation, the bars may be made removable (e.g., as a unit) for access to the fins. However, it is likely that the bars will merely be left in place during normal vacuuming.

[0023] The fins, tubes, and/or bars may have protective coatings such as that shown in WO2009/039874. Yet other variations are possible.

[0024] Although an embodiment is described above in detail, such description is not intended for limiting the scope of the present disclosure. It will be understood that various modifications may be made without departing from the scope of the disclosure. For example, when implemented in the reengineering of an existing system configuration, details of the existing configuration may influence or dictate details of any particular implementation. Accordingly, other embodiments are within the scope of the following claims.

Claims

1. A refrigerated case (20) comprising:

a body (22) having a refrigerated compartment (24);

a refrigeration system comprising:

a refrigerant flowpath (64);

a compressor (62) along the refrigerant flowpath; and

a plate fin heat exchanger (70) comprising:

a plurality of tube sections (154, 156, 158, 160) extending across an air flowpath (98), including a first group (154) of sections forming a leading group of tube sections; and

means (170) for shielding portions (182) of the fins (162) ahead of the leading group against debris accumulation,

wherein the plate fin heat exchanger is a first refrigerant-air-heat exchanger (70) in a cooling mode of operation and is a heat rejection heat exchanger and downstream of the compressor along the refrigerant flowpath;

the refrigerated case further comprising:

a second refrigerant-air heat exchanger (72) being a heat absorption heat exchanger upstream of the compressor in the cooling mode; and

an expansion device (74) along the refrigerant flowpath, downstream of the first refrigerant-air heat exchanger and upstream of the second refrigerant-air heat exchanger in the cooling mode,

wherein:

the air flowpath (98) passes across the first refrigerant-air heat exchanger;

a fan (80) is positioned along the air flowpath;

the leading group of the first plurality of tube sections (154, 156, 158, 160) is a leading group in the cooling mode;

the case comprises the means (170) for shielding the leading group against debris accumulation in the cooling mode; characterised in that the means comprises a plurality of bars (180) immediately in front of and respectively associated with individual ones of the tube sections of the leading group, at the same height thereas, and each bar extending no more than 15% of the tube diameter above or below the associated tube sections, wherein the heat exchanger is in use with vertically arranged tube sections, and not out of phase therewith; and wherein the bars (180) have trailing ends (192), and wherein the trailing ends have a positive spacing (S₁) ahead of the associated ones of the tube sections; and

the bars (180) have a v-shaped cross-section and wherein the bars (180) have trailing ends (192) having a spacing (S₂) ahead of the fins that is up to 30mm.

2. The refrigerated case of claim 1, wherein the plate fin heat exchanger is a round tube plate fin heat exchanger.

3. The refrigerated case of claim 1 wherein:

a recirculating air flowpath (100) extends from an inlet (108) positioned to receive air from the compartment to an outlet (112) positioned to discharge air to the compartment;

a second fan (82) drives a recirculating airflow (86) along the recirculating air flowpath; and

the second refrigerant-air heat exchanger (72) is within the recirculating air flowpath.

4. The refrigerated case of claim 1 wherein:
there are no similar bars adjacent a trailing group of the sections.

5. The refrigerated case of claim 1 wherein:
the bars have a cross-section downstream divergent in the cooling mode over more than half a streamwise bar span.

6. The refrigerated case of claim 1 wherein:
the bars have a height of 95-100% of a height of the associated sections.

7. The refrigerated case of claim 1 wherein:
the bars are spaced ahead of the associated sections by no more than 30mm.

8. The refrigerated case of claim 1 wherein:

the compressor and the first refrigerant-air heat exchanger are in a base of the case, below the compartment; and

in the cooling mode, the airflow is front-to back through the base.

9. A method for using the case of claim 1, the method comprising:

operating in a cooling mode wherein:

refrigerant is delivered to the second refrigerant-air heat exchanger along the refrigerant flowpath to cool air along a recirculating air flowpath, causing condensate from the recirculating air flowpath to freeze onto the second refrigerant-air heat exchanger as ice; and

the fan drives the airflow in a first direction across the first refrigerant-air heat exchanger, so that debris accumulates on the first heat exchanger; and

operating in a defrost mode wherein:

the ice is melted, causing the melted ice to flow to the drain and be discharged from the drain as said water; and

the fan drives the airflow opposite the first direction to eject the debris.

Ansprüche

1. Gekühltes Gehäuse (20), umfassend:

einen Körper (22), der ein gekühltes Fach (24) aufweist;

ein Kühlsystem, umfassend:

einen Kühlmittelströmungsweg (64);

einen Verdichter (62) entlang des Kühlmittelströmungsweges; und

einen Rippenplatten-Wärmetauscher (70), umfassend:

eine Vielzahl von Rohrteilen (154, 156, 158, 160), die sich über einen Luftströmungsweg (98) erstrecken, die eine erste Gruppe (154) von Teilen beinhaltet, die eine vordere Gruppe der Rohrteile bildet; und

ein Mittel (170) zum Abschirmen von Abschnitten (182) der Rippen (162) vor der vorderen Gruppe gegenüber einer Ansammlung von Schmutzteilchen,

wobei der Rippenplatten-Wärmetauscher ein erster Kühlmittel-Luft-Wärmetauscher (70) in einem Kühlbetriebsmodus ist und ein Wärmeabführ-Wärmetauscher ist, der sich entlang des Kühlmittelströmungsweges stromabwärts des Verdichters befindet;

wobei das gekühlte Gehäuse ferner Folgendes umfasst:

einen zweiten Rippenplatten-Wärmetauscher (72), der ein Wärmeaufnahme-Wärmetauscher stromaufwärts des Verdichters in dem Kühlmodus ist; und

eine Expansionsvorrichtung (74) entlang des Kühlmittelströmungsweges, stromabwärts des ersten Kühlmittel-Luft-Wärmetauschers und stromaufwärts des zweiten Kühlmittel-Luft-Wärmetauschers in dem Kühlmodus,

wobei:

der Luftströmungsweg (98) über den ersten Kühlmittel-Luft-Wärmetauscher führt;

ein Gebläse (80) entlang des Luftströmungsweges positioniert ist;

die vordere Gruppe der ersten Vielzahl von Rohrteilen (154, 156, 158, 160) eine vordere Gruppe in dem Kühlmodus ist;

das Gehäuse das Mittel (170) zum Abschirmen der vorderen Gruppe gegenüber einer Ansammlung von Schmutzteilchen umfasst; dadurch gekennzeichnet, dass das Mittel eine Vielzahl von Stangen (180) direkt vor einzelnen der Rohrteile der vorderen Gruppe umfasst, die diesen jeweils zugeordnet sind und sich auf derselben Höhe wie diese befinden, und sich jede Stange um nicht mehr als 15 % von dem Rohrdurchmesser über oder unter die zugeordneten Rohrteile erstreckt, wobei der Wärmetauscher mit vertikal angeordneten Rohrteilen in Gebrauch ist und nicht phasenverschoben zu diesen ist; und

wobei die Stangen (180) hintere Enden (192) aufweisen und wobei die hinteren Enden einen positiven Abstand (S₁) vor den zugeordneten der Rohrteile aufweisen; und

die Stangen (180) einen v-förmigen Querschnitt aufweisen und wobei die Stangen (180) hintere Enden (192) aufweisen, die einen Abstand (S₂) vor den Rippen aufweisen, der bis zu 30 mm beträgt.

2. Gekühltes Gehäuse nach Anspruch 1, wobei der Rippenplatten-Wärmetauscher ein Rippenplatten-Wärmetauscher mit runden Rohren ist.

3. Gekühltes Gehäuse nach Anspruch 1, wobei:

sich ein Rückführungsluftströmungsweg (100) von einem Einlass (108), der positioniert ist, um Luft aus dem Fach aufzunehmen, zu einem Auslass (112) erstreckt, der positioniert ist, um Luft in das Fach abzugeben;

ein zweites Gebläse (82) einen Rückführungsluftstrom (86) entlang des Rückführungsluftströmungswegs lenkt; und

sich der zweite Kühlmittel-Luft-Wärmetauscher (72) in dem Rückführungsluftströmungsweg befindet.

4. Gekühltes Gehäuse nach Anspruch 1, wobei:
keine ähnlichen Stangen benachbart zu einer hinteren Gruppe der Teile vorhanden sind.

5. Gekühltes Gehäuse nach Anspruch 1, wobei:
die Stangen einen Querschnitt aufweisen, der in dem Kühlmodus stromabwärts über mehr als die Hälfte einer Stangenspanne in Strömungsrichtung divergiert.

6. Gekühltes Gehäuse nach Anspruch 1, wobei:
die Stangen eine Höhe von 90-100 % einer Höhe der zugeordneten Teile aufweisen.

7. Gekühltes Gehäuse nach Anspruch 1, wobei:
die Stangen um nicht mehr als 30 mm vor den zugeordneten Teilen beabstandet sind.

8. Gekühltes Gehäuse nach Anspruch 1, wobei:

sich der Verdichter und der erste Kühlmittel-Luft-Wärmetauscher in einer Basis des Gehäuses und unter dem Fach befinden; und

der Luftstrom in dem Kühlmodus von vorne nach hinten durch die Basis verläuft.

9. Verfahren zum Verwenden des Gehäuses nach Anspruch 1, wobei das Verfahren Folgendes umfasst:

Betreiben in einem Kühlmodus, wobei:

ein Kühlmittel dem zweiten Kühlmittel-Luft-Wärmetauscher entlang des Kühlmittelströmungsweges zugeführt wird, um Luft entlang eines Rückführungsluftströmungsweges zu kühlen, wodurch Kondensat aus dem Rückführungsluftströmungsweg dazu veranlasst wird, als Eis an dem zweiten Kühlmittel-Luft-Wärmetauscher anzufrieren; und

das Gebläse den Luftstrom in einer ersten Richtung über den ersten Kühlmittel-Luft-Wärmetauscher lenkt, sodass sich Schmutzteilchen an dem ersten Wärmetauscher ansammeln; und

Betreiben in einem Abtaumodus, wobei:

das Eis geschmolzen wird, wodurch das geschmolzene Eis dazu veranlasst wird, zu dem Ablauf zu strömen und aus dem Ablauf als das Wasser abgegeben zu werden; und

das Gebläse den Luftstrom gegenüber der ersten Richtung lenkt, um die Schmutzteile auszustoßen.

Revendications

1. Vitrine réfrigérée (20) comprenant :

un corps (22) comportant un compartiment réfrigéré (24) ;

un système de réfrigération comprenant :

un trajet d'écoulement de fluide frigorigène (64) ;

un compresseur (62) le long du trajet d'écoulement de fluide frigorigène ; et

un échangeur thermique à plaque-ailette (70) comprenant :

une pluralité de sections de tube (154, 156, 158, 160) s'étendant à travers un trajet d'écoulement d'air (98), comprenant un premier groupe (154) de sections formant un groupe avant de sections de tube ; et

un moyen (170) de protéger des parties (182) des ailettes (162) devant le groupe avant contre l'accumulation de débris,

dans laquelle l'échangeur thermique à plaque-ailette est un premier échangeur thermique fluide frigorigène-air (70) dans un mode de fonctionnement de refroidissement et est un échangeur thermique à rejet de chaleur et en aval du compresseur le long du trajet d'écoulement de fluide frigorigène ;

la vitrine réfrigérée comprenant en outre :

un second échangeur thermique fluide frigorigène-air (72) étant un échangeur thermique à absorption de chaleur en amont du compresseur dans le mode de refroidissement ; et

un dispositif de détente (74) le long du trajet d'écoulement de fluide frigorigène, en aval du premier échangeur thermique fluide frigorigène-air et en amont du second échangeur thermique fluide frigorigène-air dans le mode de refroidissement,

dans laquelle :

le trajet d'écoulement d'air (98) passe à travers le premier échangeur thermique fluide frigorigène-air ;

un ventilateur (80) est positionné le long du trajet d'écoulement d'air ;

le groupe avant de la première pluralité de sections de tube (154, 156, 158, 160) est un groupe avant dans le mode de refroidissement ;

la vitrine comprend le moyen (170) de protéger le groupe avant contre l'accumulation de débris dans le mode de refroidissement ; caractérisé en ce que le moyen comprend une pluralité de barres (180) juste à l'avant de, et respectivement associées à des sections individuelles des sections de tube du groupe avant, à la même hauteur que celles-ci, et chaque barre s'étendant au maximum à 15 % du diamètre de tube au-dessus ou en dessous des sections de tube associées, dans laquelle l'échangeur thermique est en service avec des sections de tube agencées verticalement, et n'est pas décalé par rapport à celles-ci ; et dans lequel les barres (180) comportent des extrémités arrière (192), et dans laquelle les extrémités arrière comportent un espacement positif (S₁) devant les sections associées des sections de tube ; et

les barres (180) comportent une section transversale en forme de V et dans laquelle les barres (180) comportent des extrémités arrière (192) comportant un espacement (S₂) devant les ailettes qui peut aller jusqu'à 30 mm.

2. Vitrine réfrigérée selon la revendication 1, dans laquelle l'échangeur thermique à plaque-ailette est un échangeur thermique à plaque-ailette à tube rond.

3. Vitrine réfrigérée selon la revendication 1, dans laquelle :

un trajet d'écoulement d'air de recirculation (100) s'étend d'une entrée (108) positionnée pour recevoir l'air provenant du compartiment à une sortie (112) positionnée pour évacuer l'air dans le compartiment ;

un second ventilateur (82) entraîne un écoulement d'air de recirculation (86) le long du trajet d'air de recirculation ; et

le second échangeur thermique fluide frigorigène-air (72) se situe dans le trajet d'écoulement d'air de recirculation.

4. Vitrine réfrigérée selon la revendication 1, dans laquelle :
il n'existe pas de barres similaires adjacentes à un groupe arrière des sections.

5. Vitrine réfrigérée selon la revendication 1, dans laquelle :
les barres comportent une section transversale en aval divergente dans le mode de refroidissement sur plus de la moitié d'une portée de barres dans le sens d'un écoulement.

6. Vitrine réfrigérée selon la revendication 1, dans laquelle :
les barres possèdent une hauteur de 95 à 100 % d'une hauteur des sections associées.

7. Vitrine réfrigérée selon la revendication 1, dans laquelle :
les barres sont espacées devant les sections associées d'au maximum 30 mm.

8. Vitrine réfrigérée selon la revendication 1, dans laquelle :

le compresseur et le premier échangeur thermique fluide frigorigène-air se situent dans une base de la vitrine, sous le compartiment ; et

dans le mode de refroidissement, l'écoulement d'air circule d'avant en arrière à travers la base.

9. Procédé d'utilisation de la vitrine selon la revendication 1, le procédé comprenant :

un fonctionnement dans un mode de refroidissement dans lequel :

un fluide frigorigène est acheminé jusqu'au second échangeur thermique fluide frigorigène-air le long du trajet d'écoulement de fluide frigorigène pour refroidir l'air le long d'un trajet d'écoulement d'air de recirculation, amenant le condensat provenant du trajet d'écoulement d'air de recirculation à geler sur le second échangeur thermique fluide frigorigène-air sous forme de glace ; et

le ventilateur entraîne le flux d'air dans une première direction à travers le premier échangeur thermique fluide frigorigène-air, de sorte que des débris s'accumulent sur le premier échangeur thermique ;

un fonctionnement dans un mode de dégivrage dans lequel :

la glace est fondue, amenant la glace fondue à s'écouler dans la canalisation et à être évacuée de la canalisation sous la forme de ladite eau ; et

le ventilateur entraîne l'écoulement d'air à l'opposé de la première direction pour éjecter les débris.

Drawing