WO2011047291A1

WO2011047291A1 - Refrigeration display case

Info

Publication number: WO2011047291A1
Application number: PCT/US2010/052885
Authority: WO
Inventors: Chaochang Zhang; Yunyu Yang; Bo Zhou
Original assignee: Carrier Corporation
Priority date: 2009-10-16
Filing date: 2010-10-15
Publication date: 2011-04-21
Also published as: CN102038387A; EP2488068A1; CN102038387B; EP2488068B1

Abstract

A refrigeration display case (10) includes a display cabinet (12), a cooling duct (14), a refrigeration system, an air diffuser (16) and an air circulation system. The display cabinet has an inner volume (18) and an access aperture (20). The cooling duct has an airflow passage extending between an inlet (24) and an outlet (22), which inlet and outlet fluidly connect the airflow passage to the inner volume of the display case. The refrigeration system has an evaporator (44) disposed in the airflow passage. The evaporator has low and high temperature regions (54, 56). The air diffuser has a high airflow region (62) and a low airflow region (64). The high airflow region is configured to direct air toward the low temperature region. The low airflow region is configured to direct air toward the high temperature region. The air circulation system is adapted to circulate air between the cooling duct and the display cabinet.

Description

REFRIGERATION DISPLAY CASE

This application claims priority to Chinese Patent Appln. No. 200910206503.3 filed October 16, 2009, which application is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

[0001] This disclosure relates generally to refrigeration systems and, more particularly, to high efficiency refrigeration display cases.

2. Background Information

[0002] Refrigeration display cases and systems (also referred to as "merchandisers" and

"service cases") are typically used to store and/or display perishable and/or volatile goods (e.g., food, beverages, medications, etc.) in a regulated environment. A typical refrigeration display case ("display case") includes a refrigeration system and storage elements (e.g., shelves, racks, etc.) housed within an insulated enclosure. The refrigeration system includes a fan and a closed- loop system having a compressor, a condenser, an evaporator, a refrigerant regulator (e.g., a thermostatic expansion valve) and an evaporator pressure regulator (EPR) arranged in a typical fashion. The evaporator includes a plurality of tubes perpendicularly traversing a plurality of heat transfer fins. Typically, the fins and the tubes are configured such that the evaporator has a relatively low fin density (e.g., 3 fins per inch ("FPI")). That is, the evaporator is configured such that there are relatively large spaces/gaps between each fin, which reduces the heat transfer surface area of the evaporator.

[0003] During operation, refrigerant is circulated within the closed-loop system according to a typical refrigeration cycle. Air circulated within the display case is regulated, e.g. at a constant temperature and/or humidity, by transferring heat into the refrigerant as it flows through the evaporator. As heat is transferred from the circulated air to the refrigerant, a temperature gradient may be formed within the evaporator. Typically, this temperature gradient extends perpendicularly to the flow of the air through the evaporator. For example, a vertical top of the evaporator may be cooler than a vertical bottom.

[0004] In some display cases, as the circulated air travels through the evaporator, moisture condenses and forms frost crystals on some or all of the fins and the tubes thereof. This formation of frost is particularly prevalent in cooler regions of the evaporator. This frost buildup can undesirably reduce the airflow through the evaporator which thereby reduces the efficiency and effectiveness of the refrigeration system.

SUMMARY OF THE DISCLOSURE

[0005] According to an aspect of the present invention, a refrigeration display case is provided that includes a display cabinet, a cooling duct, a refrigeration system, an air diffuser, and an air circulation system. The display cabinet has an inner volume and an access aperture. The cooling duct has an airflow passage that extends between an inlet and an outlet. The inlet and outlet fluidly connect the airflow passage to the inner volume of the display case. The refrigeration system has a counterflow evaporator disposed in the airflow passage. The counterflow evaporator has low and high temperature regions. The air diffuser has high and low flow regions. The high flow region is configured to direct air to the low temperature region, and the low flow region is configured to direct air to the high temperature region. The air circulation system is adapted to circulate air between the cooling duct and the display cabinet.

[0006] According to another aspect of the present invention, a method for regulating environmental conditions in a refrigeration display case is provided. The method includes the steps of: a) providing a refrigeration display cabinet having an inner volume and an access aperture, a cooling duct having an airflow passage extending between an inlet and an outlet, and a refrigeration system including a counterflow evaporator having a low temperature region and a high temperature region, wherein the counterflow evaporator is disposed in the airflow passage; b) metering an airflow through the airflow passage such that a first quantity of the airflow is directed towards the low temperature region of the counterflow evaporator and a second quantity of the airflow is directed towards the high temperature region of the counterflow evaporator; c) cooling the first and the second quantities of air to provide cooled airflow; and d) directing a first quantity of the cooled airflow from the outlet of the cooling duct into the inner volume of the display cabinet.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a diagrammatic illustration of one embodiment of a refrigeration display case. [0008] FIGS. 2A and 2B are diagrammatic illustrations of opposite lateral sides of one embodiment of an evaporator; e.g., the lateral side view shown in FIG. 2B is shown by rotating the view of FIG. 2A about an axis parallel to one of the rows.

[0009] FIG. 3 is a planar view of an air diffuser section.

[0010] FIG. 3 A is partial expanded view of the air diffuser shown in FIG. 3.

[0011] FIG. 4 is a planar view of an air diffuser section.

[0012] FIG. 4A is partial expanded view of the air diffuser shown in FIG. 4.

[0013] FIG. 5 is a diagrammatic illustration of one embodiment of a squeezer.

[0014] FIG. 6 is a partial expanded view of a region, proximate the evaporator and air diffuser, of a cooling duct in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0015] FIG. 1 is a diagrammatic illustration of one embodiment of a refrigeration display case 10. The refrigeration display case 10 includes a display cabinet 12, a cooling duct 14, a refrigeration system, an air diffuser 16 and an air circulation system.

[0016] The display cabinet 12 has an inner volume 18 adapted to store and/or display perishable and/or volatile goods (e.g., food, beverages, medications, etc.). The display cabinet 12 includes an access aperture 20, an airflow outlet 22, an airflow inlet 24 and optionally at least one transparent panel (e.g., a glass window 26). The access aperture 20 is sized and positioned such that the goods stored/displayed in the inner volume 18 may be seen, accessed and/or removed from outside of the refrigeration display case 10. For example, as illustrated in FIG. 1, the access aperture 20 is disposed on a vertical top 28 of the display cabinet 12 adjacent a top edge 30 of the glass window 26. However, the access aperture 20 may be positioned in alternate locations depending on the configuration and intended use of the refrigeration display case 10.

[0017] The airflow inlet 24 is disposed relative to a first end 32 of the access aperture 20 and adjacent to a bottom end 34 of the glass window 26. The airflow outlet 22 is disposed proximate a second end 36 of the access aperture 20 opposite the first end 32.

[0018] The cooling duct 14 has an airflow passage 38 that extends between an airflow inlet 40 and an airflow outlet 42.

[0019] The refrigeration system includes a thermodynamic counterflow evaporator 44

("evaporator") configured in a closed loop system. Closed loop refrigeration systems are well known in the art, and the present invention is not limited to any particular configuration. One example of such a closed loop refrigeration system having a counterflow evaporator is disclosed in U.S. Patent No. 6,460,372 to Fung et al., which is hereby incorporated by reference in its entirety. Briefly, referring to FIGS. 2A and 2B, in some embodiments the evaporator 44 includes a plurality tubes 46 orientated in a plurality of rows (e.g., eight rows). The tubes 46 form a cooling region 48 (e.g., the tubes 46 in rows three through eight, where the tubes are configured such that coolant enters the cooling region 48 portion of the evaporator 44 in row three, travels up rows four through seven, and exits row eight) and a defrosting / superheating region 50 (e.g., the tubes 46 in rows two and one, where the coolant exiting row eight enters the defrosting region 50 of the evaporator 44 in row two, travels into row one, and exits the evaporator 44 thereafter). The tubes 46 in row one are located upstream of the tubes 46 in rows two through eight respectively relative to an airflow 52 directed through the evaporator 44. The evaporator 44 further includes a plurality of fins (not shown) thermally connected to the plurality of tubes 46 for facilitating heat transfer. As disclosed in the '372 Patent, the cooling fins are disposed such that the evaporator 44 has a relatively high fin density (e.g., 6 FPI). In addition, the evaporator 44 is operable to form a low temperature region 54 and a high temperature region 56. The high temperature region 56 is located proximate a first end 58 (e.g., a vertical bottom) of the evaporator 44. The low temperature region 54 is located proximate a second end 60 (e.g., a vertical top) of the evaporator 44.

[0020] FIGS. 3 and 4 diagrammatically illustrate sections 62, 64 of the air diffuser 16 shown in FIG. 1. FIGS. 3 A and 4A are partial expanded views of the diffuser sections 62, 64 shown in FIGS. 3 and 4, respectively. The air diffuser 16 includes one or more diffuser sections (e.g., first and second diffuser sections 62, 64) and a plurality of airflow passages 66. The first diffuser section 62 is connected to the second diffuser section 64. In the embodiment shown in FIG. 1 , the first diffuser section 62 is shown positioned downstream of the second diffuser section 64; i.e., airflow encounters the second diffuser section 64 before it encounters the first diffuser section 62. The plurality of airflow passages 66 are disposed in each of the first and the second diffuser sections 62, 64 forming grills/grates. Each passage 66 has a flow area and is spaced from adjacent passages by a distance. The passages are sized and positioned to form high and low flow regions 70, 72 within the first and the second diffuser sections 62, 64. For example, referring to FIGS. 3 and 3A, the passages 66 in the first diffuser section 62 are a) sized such that a flow area 68 of each passage 66 in the high and the low flow regions 70, 72 is approximately equal, and b) positioned such that a distance 74 between adjacent passages in the low flow region 72 is greater than a distance 76 between adjacent passages in the high flow region 70. Referring to FIGS. 4 and 4 A, the passages 66 in the second diffuser section 64 are a) sized such that a flow area 78 of each passage in the high flow region 70 is greater than a flow area 80 of each passage 66 in the low flow region 72, and b) positioned such that a distance 82 between adjacent passages 66 in the high and the low flow areas 70, 72 is approximately equal. Notably, the present invention is not to be limited to the aforesaid example, but rather the airflow passages 66 may be configured in numerous different sizes and arrangements to form the high and the low airflow regions 70, 72 of the air diffuser 16.

[0021] Referring again to FIG. 1, the air circulation system is configured to circulate air within the refrigeration display case 10. The air circulation system includes an air curtain system 83, a fan system (not shown) and optionally an anti-sweat heater (not shown). An anti-sweat heater can be used to reduce or eliminate dew formation on the glass window 26 of the cabinet.

[0022] The air curtain system 83 is adapted to project an air curtain 84 (e.g., a planar or wedged shaped stream of air) for separating different thermal environments; e.g., separating a relatively cool environment within the inner volume 18 of the display cabinet 12 from a relatively warm environment surrounding the refrigeration display case 10. The air curtain system 83 includes a squeezer 86 and an air dispersion device 88 having a "honey comb" configuration.

[0023] FIG. 5 is a diagrammatic illustration of one embodiment of the squeezer 86 in

FIG. 1. The squeezer 86 has a plurality of segments that include a first segment 89, a second segment 90, a third segment 92 and a fourth segment 94. The first segment 89 is disposed adjacent the second segment 90 and skewed relative to the second segment according to a first offset angle 96 (e.g., approximately 138.7°). The second segment 90 is disposed adjacent the third segment 92 and skewed relative to the third segment according to a second offset angle 98 (e.g., approximately 149.4^°). The third segment 92 is disposed adjacent to the fourth segment 94 and skewed relative to the fourth segment according to a third offset angle 100 (e.g., approximately 100.8°). The fourth segment is configured to mate with (i.e., to locate and/or to hold) the air dispersion device 88. [0024] The fan system is adapted to provide a controllable variable airflow. The fan system includes one or more fans having, for example, electronic comminuted motors.

[0025] Referring to FIG. 1, the airflow inlet 40 and the airflow outlet 42 of the cooling duct 14 fluidly couple the airflow passage 38 to the inner volume 18 of the display cabinet 12; e.g., collectively the airflow inlet and outlet 40, 42 create an air circulation pattern through the display cabinet 12. For example, airflow inlet 40 of the cooling duct 14 is connected to the airflow outlet 22 of the display cabinet 12 and the airflow outlet 42 of the cooling duct 14 is connected to the airflow inlet 24 of the display cabinet 12 via the squeezer 86. The air curtain system 83 is configured to project an air curtain 84 across the access aperture 20 of the display cabinet 12 from the squeezer 86 towards the airflow inlet 40 of the cooling duct 14.

[0026] The evaporator 44 and the air diffuser 16 are disposed within the airflow passage

38 of the cooling duct 14 such that the high flow region 70 of the air diffuser 16 is aligned with the low temperature region 54 of the evaporator 44, and the low flow region 72 of the air diffuser 16 is aligned with the high temperature region 56 of the evaporator 44. For example, the top vertical end 60 of the evaporator 44 is positioned adjacent the inner volume 18 of the display cabinet 12 and the first row of tubes 46 is disposed upstream of the eighth row of tubes 46. The first diffuser section 62 is disposed downstream of the second diffuser section 64 and the high flow region 70 of the air diffuser 16 is located adjacent the inner volume 18 of the display cabinet 12. The fan system circulates air between the airflow passage 38 of the cooling duct 14 and the inner volume 18 of the display cabinet 12.

[0027] In operation of the refrigeration display case 10 in FIG. 1, the fan system directs an airflow 102 from the airflow inlet 40 towards the air diffuser 16. The air diffuser 16 meters (i.e., separates and apportions) the airflow 102 to provide a first airflow 104 from the high flow region 70 and a second airflow 106 from the low flow region 72 thereof. For example, now referring to FIG. 6, the second diffuser section 64 meters the airflow 102 such that a greater quantity of air is directed from a vertical top of the second diffuser section 64 than a vertical bottom thereof (see airflow 103). The first diffuser section 62 meters the airflow 103 directed from the second diffuser section 64 such that an even greater quantity of air is directed from a vertical top of the first diffuser section 62 than a vertical bottom thereof. The vertical top half of the airflow directed from the first diffuser section 62 forms the first airflow 104 and the vertical bottom half thereof forms the second airflow 106. As set forth above, the first airflow 104 is greater that the second airflow 106; i.e., a greater quantity of air flows through the high flow region 70 of the air diffuser 16 than the low flow region 72. Accordingly, the first airflow 104 carries more heat energy than the second airflow 106.

[0028] A temperature gradient is formed (e.g., by coolant flow characteristics) in the evaporator 44 perpendicular to the air flow path of the first and the second airflows 104, 106. The temperature gradient in turn forms the low and the high temperature regions 54, 56 within the evaporator 44 such that the second end 60 (i.e., the top end) thereof is cooler than the first end 58 (i.e., the bottom end).

[0029] The first airflow 104 from the high flow region 70 of the air diffuser 16 is directed toward the low temperature region 54 of the evaporator 44. The second airflow 106 from the low flow region 72 of the diffuser 16 is directed toward the high temperature region 56 of the evaporator 44. Heat is transferred from the first and the second airflows 104, 106, through the low and the high temperature regions 54, 56 of the evaporator 44, and into refrigerant flowing through the cooling and the defrosting regions 48, 50. This heat transfer pattern cools the first and the second airflow 104, 106, while conversely heating the refrigerant within the evaporator 44. Notably, the low temperature region 54 is heated more via the first airflow 104 than the high temperature region 56 is heated via the second airflow 106 (or than the low temperature region 54 would have been heated without the air diffuser 16 concentrating the first airflow 104 thereon). This additional heat energy transferred to the low temperature region 54 helps to raise the steady state temperature of the low temperature region 54 and prevent the formation of frost thereon. However, where frost does accumulate on the tubes 46 of the evaporator 44, the fans system may compensate for associated flow restrictions by increasing the flowrate of the first and the second airflows 104, 106.

[0030] The cooled first and second airflows 104, 106 are rejoined and directed from the evaporator 44, through the airflow outlet 42 of the cooling duct 14, and into the squeezer 86. The squeezer 86 directs the cooled airflow 108 into the inner volume 18 of the display cabinet 12. A first relatively large portion 110 of the cooled airflow circulates throughout the inner volume 18, cooling the goods and the environment within the inner volume 18. A second relatively small portion 112 of the cooled airflow extends across the access aperture 20 forming an air curtain 84 to separate the cooled environment within the inner volume 18 from the environment outside of the refrigeration display case 10. The two portions of the airflow are rejoined and directed through the airflow outlet 22 of the display cabinet 12 and into the airflow inlet 40 of the cooling duct 14 for recirculation and re-cooling.

[0031] While various embodiments of the present invention have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and

implementations are possible within the scope of the invention. Accordingly, the present invention is not to be restricted except in light of the attached claims and their equivalents.

Claims

What is claimed is:

1. A refrigeration display case, comprising:

a display cabinet having an inner volume and an access aperture;

a cooling duct having an airflow passage extending between an inlet and an outlet, which inlet and outlet fluidly connect the airflow passage to the inner volume of the display case; a refrigeration system having an evaporator disposed in the airflow passage, the evaporator having low and high temperature regions;

an air diffuser having a high airflow region and a low airflow region, wherein the high airflow region is configured to direct air toward the low temperature region, and wherein the low airflow region is configured to direct air toward the high temperature region; and

an air circulation system adapted to circulate air between the cooling duct and the display cabinet.

2. The display case of claim 1 , wherein the air diffuser includes a plurality of apertures positioned in the high airflow region and in the low airflow region.

3. The display case of claim 2, wherein the apertures in the high airflow region have a first flow area and the apertures in the low airflow region have a second flow area, and the second flow area is smaller than the first flow area.

4. The display case of claim 2, wherein the apertures in the high airflow region are separated from one another by a first distance, and the apertures in the low airflow region are separated from one another by a second distance, wherein the second distance is greater than the first distance.

5. The display case of claim 2, wherein the diffuser includes a first diffuser section and a second diffuser section, wherein the second diffuser section is disposed downstream of the first diffuser section.

6. The display case of claim 1, wherein the air circulation system comprises an air curtain system adapted to project an air curtain across the access aperture.

7. The display case of claim 6, wherein the air curtain system comprises a squeezer adapted to direct a first quantity of air into the inner volume of the display cabinet, and a second quantity of air to form the air curtain.

8. The display case of claim 1, wherein the air circulation system comprises at least one variable speed fan.

9. The display case of claim 1 , wherein the counterflow evaporator includes cooling and defrosting regions.

10. A method for regulating environmental conditions in a refrigeration display case that has an inner volume defined in part by an access aperture, a cooling duct having an airflow passage extending between an inlet and an outlet, and a refrigeration system that includes an evaporator having a low temperature region and a high temperature region, which evaporator is disposed in the airflow passage, the method comprising the steps of:

directing airflow from the display case inner volume to the airflow passage;

metering the airflow within the airflow passage to form a first airflow rate directed towards the low temperature region of the evaporator and a second airflow rate directed towards the high temperature region of the evaporator, wherein the first airflow rate is greater than the second airflow rate; and

cooling the airflow within the evaporator.

1 1. The method of claim 10, further comprising the step of projecting a portion of the airflow exiting the outlet of the airflow passage to form an air curtain across the access aperture.

12. The method of claim 11, further comprising the step of adjusting the first airflow rate and the second airflow rate in an amount that inhibits frost buildup on the evaporator.