[0001] The present invention relates to a heat exchanger, and more particularly, to a heat exchanger including fins and one or more microchannel coils.

BACKGROUND

[0002] Refrigeration systems are well known and widely used in supermarkets and warehouses to refrigerate food product displayed in a product display area of a refrigerated merchandiser or display case. Conventional refrigeration systems often include an evaporator, a compressor, and a condenser connected in series. The evaporator provides heat transfer between a refrigerant and a fluid passing over the evaporator coil. The evaporator transfers heat from the fluid to the refrigerant so that the fluid cools the product display area. The refrigerant absorbs heat from the fluid in a refrigeration mode, and the compressor mechanically compresses the evaporated refrigerant from the evaporator and feeds the superheated refrigerant to the condenser, which cools the refrigerant via heat transfer between the condenser coil and a fluid (typically ambient air) flowing through the condenser. From the condenser, the cooled refrigerant is fed through one or more expansion valves to reduce the temperature and pressure of the refrigerant, and then the refrigerant is directed through the evaporator.

[0003] Commercial refrigerators use heat exchangers for the purpose of absorbing heat from the air stream to reduce the temperature of the air and use that air mass to cool product. In most below-freezing applications this is done with a traditional fin and tube design. On the condensing side of the system, microchannel coils are becoming increasingly more common, but due to fin density and design the microchannel coils ice over rapidly in below-freezing applications.

SUMMARY

[0004] In one construction, the invention embodies a heat exchanger including a coil that has bends and tube passes that are disposed between the bends. The coil further has an inlet end and an outlet end and is continuous between the inlet end and the outlet end. The coil is defined by parallel microchannel passageways extending from the inlet end to the outlet end. The heat exchanger also includes a plurality of elongated fins spaced apart from each other between a first end of the heat exchanger and a second end of the heat exchanger. Each of the fins defines two or more apertures, and two or more of the tube passes extend through the same fin of the plurality of fins.

[0005] In another construction, the invention embodies a heat exchanger including a serpentine coil that has an inlet end and an outlet end and that is continuous between the inlet end and the outlet end. The serpentine coil is defined by parallel fluid passageways extending from the inlet end to the outlet end. The heat exchanger also includes one or more fins disposed between a first end of the heat exchanger and a second end of the heat exchanger, and each of the one or more fins is coupled to different portions of the serpentine coil.

[0006] In yet another construction, the invention embodies a heat exchanger including a coil that has bends and tube passes disposed between the bends. The coil further has an inlet end and an outlet end and being continuous between the inlet end and the outlet end. The coil is defined by parallel microchannel passageways extending from the inlet end to the outlet end. The heat exchanger also includes a plurality of fins spaced apart from each other between a first end of the heat exchanger and a second end of the heat exchanger, and each of the plurality of fins is coupled to and surrounds multiple tube passes of the coil.

[0007] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Fig. 1 is a section view of a refrigerated merchandiser including a heat exchanger embodying the present invention.

[0009] Fig. 2 is a perspective view of the heat exchanger of Fig. 1 from adjacent a first side and including fins and microchannel coils circuits extending through the fins.

[0010] Fig. 3 is a perspective view of the heat exchanger of Fig. 1 from adjacent a second side opposite the first side.

[0011] Fig. 4 is a perspective view of an exemplary continuous microchannel coil circuit of the heat exchanger of Figs. 2 and 3.

[0012] Fig. 5 is a cross section of a portion of two adjacent continuous microchannel coil circuits of Fig. 2 taken along line 5— 5 in Fig. 2. [0013] Fig. 6 is an end view of the heat exchanger of Fig. 2 from adjacent the first end of the heat exchanger.

[0014] Fig. 7 is an end view of the heat exchanger of Fig. 2 from adjacent the second end of the heat exchanger.

[0015] Fig. 8 is a cross section of the heat exchanger of Fig. 2 taken along line 8— 8 in Fig. 2.

[0016] Fig. 9 is an enlarged view of a portion of the heat exchanger of Fig. 8. DETAILED DESCRIPTION

[0017] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

[0018] Fig. 1 illustrates an exemplary refrigerated merchandiser 10 that may be located in a supermarket or a convenience store or other retail setting (not shown) for presenting fresh food, beverages, and other product (not shown). As shown, the merchandiser 10 is an upright merchandiser with an open front. The merchandiser 10 can be an upright merchandiser that is provided with or without doors, a horizontal merchandiser with an open or enclosed top, or another type of merchandiser.

[0019] The refrigerated merchandiser 10 includes a case 100 that has a base 104, a rear wall 108, and a canopy or case top 112. The area that is partially enclosed by the base 104, the rear wall 108, and the canopy 112 defines a product display area 116. As illustrated, the product display area 116 is accessible by customers through an opening 120 adjacent the front of the case 100. Shelves 124 are coupled to the rear wall 108 and extend forward toward the opening 120 adjacent the front of the merchandiser to support food product that is accessible by a consumer through the opening 120.

[0020] The base 104 defines a lower portion of the product display area 116 and can support food product. The base 104 further defines a lower flue 134 and includes an inlet 138 located adjacent a lower area of the opening 120. As illustrated, the lower flue 134 is in fluid communication with the inlet 138 and directs an airflow 144, which is generated by a fan 146 that is coupled to the case 100, substantially horizontally through the base 104 from the inlet 138. The inlet 138 is positioned to receive surrounding air in a substantially vertical direction and directs the air into the lower flue 134.

[0021] With continued reference to Fig. 1, the case 100 includes a rear flue 148 extending upward from the base 104 and in fluid communication with the lower flue 134. The rear flue 148 and the lower flue 134 cooperatively define a corner 150 in the air passageway. The rear flue 148 is defined by the rear wall 108 and an intermediate wall 151 spaced apart from the rear wall 108, and directs the airflow 144 generally vertically through the case 100. In some constructions, the rear wall 108 can include apertures (not shown) that fluidly couple the rear flue 148 with the product display area 1 16 to permit at least some of the airflow 144 to enter the product display area 116.

[0022] The canopy 1 12 defines an upper flue 156. The upper flue 156 is in fluid communication with the rear flue 148 and directs the airflow 144 substantially horizontally through the canopy 112 toward an outlet 160. The lower flue 134, the rear flue 148, and the upper flue 156 are fluidly coupled to each other to define an air passageway that directs the airflow 144 from the inlet 138 to the outlet 160.

[0023] The airflow that is discharged from the outlet 160 forms an air curtain 174 that is directed generally downward across the opening 120 to cool the food product within a desired or standard temperature range (e.g., 32 to 41 degrees Fahrenheit). Generally, the inlet 138 receives at least some air from the air curtain 174. Although not shown, the case 100 can define a secondary air passageway that directs a secondary air curtain (e.g., refrigerated or non-refrigerated) from the canopy 112 generally downward across the opening 120 to buffer the air curtain 174 to minimize infiltration of ambient air into the product display area 116.

[0024] As illustrated in Fig. 1, the merchandiser also includes a hybrid heat exchanger 190 that is positioned in a lower portion of the rear flue 148. The illustrated heat exchanger 190 transfers heat from the airflow 144 to refrigerant flowing through the heat exchanger 190. As oriented, the airflow 144 passes substantially vertically through the heat exchanger 190. Due to the positioning of the heat exchanger 190 proximate the corner 150, the vertical airflow 144 may not be identically uniform across a width W of the heat exchanger 190 (see Fig. 1). In other constructions, the heat exchanger 190 may be located anywhere within the lower flue 134, the rear flue 148, or the upper flue 156. In further constructions, the refrigerated merchandiser 10 may include more than one heat exchanger 190 (e.g., positioned across a width of the case 100). Although the invention is described with regard to the heat exchanger 190 being positioned in and used in the context of a refrigerated merchandiser, it will be understood that the invention embodied herein and in the claims can be implemented in other structures.

[0025] Referring to Figs. 2, 3, and 6, the heat exchanger 190 is divided along a width W into six zones 1 , 2, 3, 4, 5, 6. Each zone 1 -6 extends a length L of the heat exchanger 190 between a first end 194 and a second end 200 of the heat exchanger 190 and delineates an airflow section of the heat exchanger that receives a portion of the airflow 144 through the heat exchanger 190. In other constructions, the zones 1-6 may extend less than the length L of the heat exchanger 190. In the exemplary heat exchanger 190 shown in Figs. 2-7, an inlet manifold 204 at the first end 194 distributes refrigerant to inlets of a series of six independent coil or tube circuits 210A, 210B, 210C, 210D, 210E, 210F (referred to interchangeably as coils or circuits 210A-F). As shown, the six coil circuits 210A-F extend from the first end 194 to the second end 200 of the heat exchanger 190 and pass through a plurality of generally equally spaced and substantially parallel elongated fins 214 (additional interior fins, which may also vary in fin density - that is, fins per inch - are not shown for clarity). Furthermore, an outlet manifold 220 coupled to outlets of each coil circuit 210A-F is adjacent the first end 194 and ultimately collects refrigerant that has passed through the coil circuits 210A-F and directs the refrigerant for recirculation through the refrigerant system (not shown).

[0026] Each coil circuit 210A-F includes a plurality of tube passes 225 (e.g., twelve tube passes 225 in each coil circuit 210A-F as illustrated in Fig. 4) with the length of a single tube pass 225 extending the length L of the heat exchanger 190. In other constructions, each coil circuit 210A-F may include more or fewer than twelve tube passes 225. With reference to Fig. 3, no tube pass 225 crosses from one zone to another zone along the length of the heat exchanger 190 or at the second end 200. That is, each tube pass 225 extends from the first end 194 to the second end 200 within a single zone. As illustrated in Fig. 5, the longitudinal extent of each tube pass 225 defines a tube plane 230 that is oriented at an acute, non-zero angle 235 relative to a vertical plane 240 (e.g., defined along an edge of a fin) and relative to a horizontal plane 245 (e.g., defined along an edge of the fin that is perpendicular to the other edge). In the illustrated construction, the tube plane 230 is disposed at approximately 60 degrees relative to the horizontal plane 245. In other constructions, the tube plane 230 may be vertical (parallel to the plane 240), horizontal (parallel to the plane 245), or disposed at any angle 235 between horizontal and vertical. In the illustrated construction, each tube pass 225 in a single zone is oriented parallel with each of the remaining tube passes 225 in that zone, and the tube passes 225 in adjacent zones (e.g., zone 1 and zone 2, zone 2 and zone 3, zone 3 and zone 4, zone 4 and zone 5, zone 5 and zone 6, etc.) are oriented non-parallel with each other (best seen in Fig. 9).

[0027] In some constructions, one or more tube passes 225 can be oriented parallel to the vertical plane 240 or the horizontal plane 245 with one or more other tube passes 225 oriented at the non-zero angle 235. When the tube plane 230 is vertical compared to being horizontal, heat transfer between the airflow and the heat exchanger 190 increases, but the velocity of the airflow traveling through the heat exchanger 190 decreases (e.g., the static pressure of the airflow increases). In contrast, when the tube plane 230 is horizontal compared to being vertical, heat transfer between the airflow and the heat exchanger 190 decreases, but the velocity of the airflow traveling through the heat exchanger 190 increases (e.g., the static pressure of the airflow decreases). Therefore, when the tube plane 230 is disposed at an angle 235 between the horizontal and vertical, an inverse relationship is observed between the amount of heat transfer and the velocity of the airflow traveling through the heat exchanger 190.

[0028] As best seen in Figs. 2 and 3, adjacent tube passes 225 of each coil circuit 210A-F are fluidly coupled together by a crossover bend portion 250 at the first end 194 and are fluidly coupled together by a return bend portion 255 at the second end 200. In the illustrated construction, each coil circuit 210A-F includes five crossover bend portions 250 and six return bend portions 255. In other constructions, the coil circuits 210A-F may include more or fewer than the five crossover bend portions 250 and/or six return bend portions 255 based on the quantity of tube passes 225.

[0029] With reference to Fig. 3 and 7, the return bend portions 255 project from the last fin 214 at the second end 200 (i.e. the second end fin 214). Each return bend portion 255 is located within one of the zones 1-6 and seamlessly joins two adjacent tube passes 225 that extend through the length L of the heat exchanger 190 within the corresponding zone 1 -6. As shown, the return bend portions 255 maintain a parallel relationship between adjacent tube passes 225 within the same coil circuit 210A-F (e.g., the tube planes 230 of adjacent passes 220 are parallel). More specifically, the return bend portions 255 located within the zones 1, 3, and 5 are twisted so that an inlet and an outlet of each return bend portion 255 (in the direction of refrigerant flow) are parallel, whereas the return bend portions 255 located within the zones 2, 4, and 6 are generally only curved so that an inlet and an outlet of each return bend portion 255 are parallel (Fig. 3).

[0030] With reference to Figs. 2 and 4, the crossover bend portions 250 for each of the circuits 210A-F project from the last fin 214 at the front end 194. First crossover bend portions 250a join two adjacent tube passes 225 to direct the circuits 210A-F from one zone to an adjacent zone (e.g., from the first zone 1 to the second zone 2). The illustrated first crossover bend portions 250a change the orientation between adjacent tube passes 225 such that adjacent tube passes 225 are obliquely oriented relative to each other (e.g., the tube planes 230 of adjacent tube passes 225 are obliquely oriented; Fig. 6). Second crossover bend portions 250b also join two adjacent tube passes 225, but the second crossover bend portions 250b direct the circuits 210A-F from one zone to a nonadjacent zone (e.g., from the first zone 1 to the third zone 3). As illustrated, the second crossover bend portions 250b maintain a parallel relationship between adjacent tube passes 225 (e.g., the tube planes 230 of adjacent passes 220 are parallel; Fig. 6).

[0031] As illustrated, each coil circuit 210A-F is formed from a continuous microchannel tube that is bent into a serpentine shape (e.g., the third coil circuit 210C is illustrated in Fig. 4 and is representative of the serpentine shape of the coil circuits 21 OA, 210B, 210D-F). More specifically, and with reference to Fig. 5, the microchannel tube defining each coil circuit 210A-F has internal walls 260 that cooperate with each other and the exterior wall of the tube to define a plurality of internal, parallel channels or fluid passageways 265. The channels 265 of each coil circuit 210A-F extend continuously along the entire length of each circuit 210A- F between the inlet manifold 204 and the outlet manifold 220. As shown in Fig. 5, a cross section of one tube pass 225 of each of the second and third coil circuits 210B, 2 IOC is illustrated and is representative of the cross sections of each tube pass 225 of the coil circuits 210A-F. In the illustrated construction, the tube plane 230 defined by the second coil circuit 210B is oriented non-parallel to the tube plane 230 defined by the third coil circuit 210C, and each of the coil circuits 210B, 210C includes ten channels 265A-J. In other constructions, each tube circuit 210A-F may include more or fewer than ten channels 265. The illustrated microchannel tube circuits 210A-F can be formed from any suitable material (e.g., metal such as an aluminum alloy or copper). While the microchannel tubes are illustrated with a substantially rectangular cross-section, other tube shapes (e.g., circular, oval, polygonal, and the like) are also possible and considered herein.

[0032] As shown in Figs. 8 and 9, each tube pass 225 of each of the coil circuits 210A-F extends through a series of apertures 270 formed in the fins 214. That is, each tube pass extends through each fin 214 once such that two or more of the tube passes extend through the same fin 214. Stated another way, each of the fins 214 is coupled to different portions of each coil 210A-F. The apertures 270 in each fin 214 linearly align between the first and second ends 194, 200 of the heat exchanger 190 along the length L to accommodate the tube passes 225. The shape of the apertures 270 conforms to the shape of the tube passes 225 extending therethrough, and each aperture 270 is oriented at the angle 235 to accommodate the tube passes 225.

[0033] The heat exchanger 190 is assembled by inserting each tube pass 225 within a corresponding series of apertures 270 of the fins 214. In an exemplary embodiment, the heat exchanger 190 can be assembled in the same or a similar manner as described and illustrated in U. S. Patent Application No. 13/768,238, filed February 15, 2013, (entitled "Multi-Zone Circuiting for a Plate-Fin and Continuous Tube Heat Exchanger"), the entire contents of which are incorporated herein by reference. For example, the tube passes 225 extend through each fin 214 so that the return bend portions 255 are coupled to two tube passes 225 adjacent the last fin 214 at the second end 200, and the crossover bend portions 250a, 250b are coupled to two tube passes 225 adjacent the fin 214 at the first end 194 to construct each coil circuit 210A-210F. In particular and with reference to Figs. 3 and 6, each of the plurality of fins 214 is coupled to and surrounds multiple tube passes 225 of the coil circuits 210A-F, and the bend portions 250 are coupled to the tube passes 225 so that each coil circuit 210A-F passes through a plurality of zones.

[0034] As illustrated, the first circuit 21 OA passes from the first zone 1 to the second zone 2, from the second zone 2 to the third zone 3, from the third zone 3 to the first zone 1 , from the first zone 1 to the second zone 2, and from the second zone 2 to the third zone 3. The second circuit 210B passes from the second zone 2 to the third zone 3, from the third zone 3 to the first zone 1 , from the first zone 1 to the second zone 2, from the second zone 2 to the third zone 3, and from the third zone 3 to the first zone 1. The third circuit 210C passes from the third zone 3 to the first zone 1 , from the first zone 1 to the second zone 2, from the second zone 2 to the third zone 3, from the third zone 3 to the first zone 1, and from the first zone 1 to the second zone 2. The four circuit 210D passes from the fourth zone 4 to the fifth zone 5, from the fifth zone 5 to the sixth zone 6, from the sixth zone 6 to the fourth zone 4, from the fourth zone 4 to the fifth zone 5, and from the fifth zone 5 to the sixth zone 6. The fifth circuit 21 OE passes from the fifth zone 5 to the sixth zone 6, from the sixth zone 6 to the fourth zone 4, from the fourth zone 4 to the fifth zone 5, from the fifth zone 5 to the sixth zone 6, and from the sixth zone 6 to the fourth zone 4. The sixth circuit 21 OF passes from the sixth zone 6 to the fourth zone 4, from the fourth zone 4 to the fifth zone 5, from the fifth zone 5 to the sixth zone 6, from the sixth zone 6 to the fourth zone 4, and from the fourth zone 4 to the fifth zone 5. In the illustrated construction, the connections between the tube passes 225 and the bend portions 250, 250a, 250b and the connections between the coil circuits 210A-F and the manifolds 204, 245 are provided by a brazing operation.

[0035] Although the heat exchanger 190 includes six zones 1-6 and six coil circuits 210A-F, heat exchangers with fewer or more than six zones and six coil circuits are possible and considered herein. Also, the horizontal and/or vertical spacing between the tubes of each coil circuit or between the coil circuits can be modified as desired. Other tube patterns also can be incorporated into the heat exchanger (e.g., inline, staggered, angled, etc.).

[0036] In operation, refrigerant from the refrigerant system (not shown) is directed from the inlet manifold 204 and is dispersed through the coil circuits 210A-F such that refrigerant passes within zones 1-6 toward the return bend portions 255 at the second end 200. The return bend portions 255 route the refrigerant back through the heat exchanger 190 toward the first end 194 so that refrigerant is again routed back through the heat exchanger 190 within different zones 1 -6 toward the second end 200 via the crossover bends 270. The back and forth movement of the refrigerant between the first and second ends 194, 200, as well as the refrigerant passing through different zones 1-6 repeats until the refrigerant reaches the outlet manifold 220. As the refrigerant travels through the heat exchanger 190, heat is absorbed in the coil circuits 210A-F via the airflow 144, and the vaporized refrigerant is collected from each coil circuit 210A-F at the outlet manifold 220 and thereafter dispersed back to the remainder of the refrigerant system. The amount of time the refrigerant in the circuits 210A-F spends in each zone (refrigerant passage time) directly correlates with the amount of thermal balancing between the circuits 210A-210F. Shifting individual coil circuits between zones 1- 6 balances the refrigerant superheat levels within each circuit, maximizing the heat transfer rate from the air to the refrigerant and more uniformly cooling the air across the entire width of the heat exchanger 190. The microchannel design of the coil circuits 210A-F also provides an increased cooling capacity of the heat exchanger 190 compared to conventional heat exchangers 190. Due to the larger spacing between the microchannel circuits 210A-F achieved by the hybrid heat exchanger 190 when compared to conventional microchannel heat exchangers, the heat exchanger 190 is less susceptible to ice formation in below freezing applications.

[0037] Various features and advantages of the invention are set forth in the following claims.