MXPA99001867A - Improved entry for an evaporative - Google Patents

Abstract

The present invention relates to an evaporator comprising a pair of spaced heads, characterized in that it comprises: at least one tube that extends between the heads and in fluid communication with each one on one side thereof and that defines a plurality of passages or spaced passages for the refrigerant, which extend between the heads, and at least one inlet for the refrigerant inside one of the heads, the inlet has a first hole adapted to be connected to a source of refrigerant to be evaporated and seconds and third holes directed oppositely connected to the first hole, the second hole is directed away from one of the sides and the third hole is directed towards the other one.

Description

ENHANCED ENTRY FOR AN EVAPORATOR FIELD OF THE INVENTION This invention is concerned with refrigerant evaporators and more particularly with an improved inlet for such an evaporator, to improve the efficiency of the evaporation operation.

BACKGROUND OF THE INVENTION Commonly assigned U.S. patents 5,341,870, issued August 30, 1994 and 5,533,259, issued July 9, 1996 to Hughes et al., The entire disclosure of which is incorporated herein by reference, describe Unique evaporators for refrigerants that are ideally suited for use in residential air conditioning applications. While the structures described in the HugHh.es et al patents work well for their intended purpose and are certainly a considerable improvement over conventional evaporators used in air conditioning systems, they are subject to the same difficulties in terms of efficiency if the refrigerant is not properly distributed inside the evaporator. When a poor distribution is present, one section of the evaporator core is frequently flooded with liguid refrigerant, while another section is essentially depleted of refrigerant. An example of a poor distribution, based on the infrared thermal image of an actual evaporator is shown in Figure 1. This dispenser is of the general configuration illustrated in the Hughes et al patents identified above and is of the type in which a head 10 can be provided with an inlet fitting 12 and the opposite head provided with an outlet fitting 16. That is to say, the illustrated evaporator is what is known in the trade as a "V" evaporator for feeding the end, extracting the end of the parallel flow variety. The tubes interconnecting the heads 10 and 14 are illustrated schematically at 18 and of course, serpentine fins (not shown) extend between adjacent tubes of the tubes 18. In such an evaporator, the tubes that are devoid of refrigerant rapidly deplete the liquid or mixed refrigerant. Consequently, dimensionable percentages of the length of each exhausted tube contain superheated, single-phase gaseous refrigerant. The heat transfer is poor. In addition, the surface temperatures of the air side where there is superheated gas flow are usually at a temperature higher than the spray point and consequently there will be no condensation of moisture from the air flowing through the evaporator in those areas of the superheated flow. Thus, no dehumidification is carried out in those areas.

Where dehumidification is carried out, moisture will be present on the outside of the tubes and will increase the resistance to air flow through the evaporator at those sites. That is, the resistance to air flow will be lower in those areas of superheated flow and consequently, the superheated areas receive a disproportionate amount of total air flow through the evaporator, to further reduce efficiency. Flooded tubes produce excellent heat transfer from start to finish, but frequently fail to evaporate all the liquid refrigerant. Consequently, the refrigerant without evaporating is not put to use and the work employed in the condensation of steam to liquid is essentially wasted. In addition, the presence of non-evaporating liquid in the suction line can cause the thermal expansion valves used in the system to "oscillate" (or become unstable). An unstable operation will result. As seen in Figure 1, the areas where the flow of superheated gas is presented are shaded. In contrast, the unshaded areas indicate areas of proper functioning or areas where the tubes are flooded. The present invention is aimed at obtaining a more uniform distribution of the refrigerant in the evaporators in general and in the "V" evaporators of the parallel flow variety by eliminating or minimizing the areas in the evaporator core that may be depleted of refrigerant and that result in excessive overheating of the refrigerant.

BRIEF DESCRIPTION OF THE INVENTION It is a principal object of the invention to provide a new and improved evaporator for a refrigerant. More specifically, it is an object of the invention to provide a new and improved input structure for an evaporator, for a refrigerant, to obtain a more uniform distribution of the refrigerant within the evaporator. An exemplary embodiment of the invention obtains the above object in an evaporator that includes a pair of spaced heads. At least one of the tubes extends between the heads and is in fluid communication with each on one side thereof and defines a plurality of spaced-apart passages for the coolant, which extend between the heads. At least one inlet for the coolant is located on one of the heads. The inlet has a first orifice connected to a source of refrigerant to be evaporated and a second orifice connected to the first orifice and located within a head and directed away from one side of the head. As a result, the refrigerant to be evaporated is sprayed onto the inside of the head opposite the location of the coolant passages and the head itself serves as a shock distributor. In a preferred embodiment, the inlet includes a third hole which is also connected to the first hole. The third hole is directed opposite the second hole and towards the side of the head containing the passages. Thus, the third hole provides a shock distribution of the coolant for the tubes closely adjacent to the inlet, while the second orifice provides a shock distribution for the passages furthest from the inlet. In a preferred embodiment, the third hole is smaller than the second hole. Preferably, the plurality of passages is defined by a plurality of the tubes and the tubes in the plurality are spaced from each other. In a preferred embodiment, the plurality of tubes have respective tube ends that enter one side of each of the heads. Preferably, each tube further defines a plurality of spaced passages for the refrigerant. In a highly preferred embodiment, the head is elongated and there are a plurality of coolant inlets spaced along the length of the head.

Also in a preferred embodiment, at least one head is generally tubular. A preferred embodiment contemplates an evaporator that includes an elongated head. A plurality of spaced flat tubes are provided and have ends that are received on one side of the head in equally spaced relationship. An inlet is provided to the head and includes a plurality of spaced injectors, each adapted to be connected to a common source of refrigerant to be evaporated. Each injector includes a discharge orifice directed away from the side of the head that receives the ends of the flat tubes. In a preferred embodiment, the ends of the tubes extend into the head and the injectors are located between the ends of pairs of adjacent tubes. Preferably, the discharge orifices are mainly discharge orifices and each injector further includes a second discharge orifice that is smaller than the primary discharge orifice and which is directed towards one side of the head, between the ends of pairs of tubes adjacent. Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of an evaporator made according to the prior art; Figure 2 is a perspective view of an evaporator made according to the invention; Figure 3 is an enlarged fragmentary view of an inlet injector used in the evaporator; Figure 4 is a fragmentary, enlarged sectional view of the inlet injector; and Figure 5 is a view similar to Figure 1, but illustrating an evaporator made according to the invention.

Description of the preferred embodiment An exemplary embodiment of the invention is illustrated in Figures 2-5, inclusive and will be described herein in the context of a so-called "V" evaporator of the parallel flow type. However, it should be understood that the invention is not limited to such evaporators. It can be used effectively in any evaporator that has a head that is in fluid communication with a plurality of spaced-apart passages for refrigerant. The evaporator includes an inlet head 20, in the form of an elongated tube. Also included is an output 22 head. A series of multi-orifice, flat tubes 24 interconnect the heads 20 and 22. Flanges 26 are arranged in a coil between adjacent flat tubes 24. The outlet head 22 includes a single outlet fitting 28, which may be of conventional construction. The inlet head 20, at equally spaced locations along its length, in a preferred embodiment, receives four refrigerant injectors 30, 32, 34 and 36. The injectors 30, 32, 34 and 36 may be common tubes that are all connected to a conventional distributor 38, which in turn can be connected to a common source of liquid refrigerant, that is, finally the condenser of a refrigeration system, either used for pure cooling purposes, heat pumps or purposes of air conditioning or all three. With reference to Figure 3, each of the tubes 24 has an end 40 that extends a substantial distance into the interior of the input head 20. The ends 40 of the tube reveal that each tube itself includes a plurality of spaced apart passages 42, which are preferably of a hydraulic diameter of 0.1778 cm (0.07 inches) or less. The hydraulic diameter is conventionally defined, that is, four times the cross sectional area of each passage 42 divided by the wet perimeter of the passage or passage. The ends 40 are spaced apart and as can be seen in figure 3, an injector representative of the injectors, ie the injector 34 is located between the ends of a pair of adjacent tubes 24. As can also be seen, the injector 34 and the injectors 30, 32 and 36 are formed of a round tube of smaller diameter than the tube forming the inlet head 20. The injector 34 enters the head 20 at angles nominally straight thereto, also as to the plane defined by the tubes 24 near the head 20. As seen in Figure 4, the tubes 24 enter a side 44 of the head 20 with the ends 40 which extend almost in half through the interior of the head 20. The injector 34 includes a sealed end 48 inside the head 20. Opposite thereto is an orifice 49 to be connected to receive the refrigerant. The injector 34 also includes a first discharge orifice 50 or primary orifice, which discharges against the inner side 52 of the head 20 which is opposite the side 44 where the tubes 24 enter the head 20. A secondary discharge orifice 54 is also located in the injector 34 within the head 20 in a common central line with the primary discharge orifice 50. The secondary discharge orifice 54 is smaller in size than the primary discharge orifice and directs the liquid refrigerant to the side 44. The injection point may be at a location between adjacent ends of the tube ends 40 or at an aligned site with one end of the tube. The spray of liquid exiting the primary discharge orifice is dispersed along the inner side 52 of the head 20 to distribute the coolant over a substantial distance within the head, such that all of the tubes 24 between sites of injectors 30, 32, 34 and 36 receive refrigerant. In many cases, only the primary discharge ports 50 are required. However sometimes, particularly where the ends 40 of the tubes extend a substantial distance into the interior of the head 20., those tubes in immediate proximity to the injectors 30, 32, 34 or 36 may not receive sufficient refrigerant, because it is literally blown beyond its ends 40, as a result of the impact on the inner surface 52. Thus, the orifices 54 secondary discharge can be provided in each injector 30, 32, 34 and 36 to ensure that the tubes 24 closely adjacent to each site of the injector receive an appropriate supply of liquid refrigerant. Figure 5 represents the infrared thermal image of a real evaporator made according to the invention. The shaded areas on it represent areas where the superheated steam flow occurs. It will be seen that the use of the invention in the evaporator of Figure 5 substantially reduces such areas to greatly improve the operating efficiency of the evaporator with respect to that shown in Figure 1. In an evaporator such as that illustrated, which is designed as an evaporator of 30, 000 BTU / hour, there are four points of the injector. Each injector is made from a tube that has an outside diameter of 0.635 cm (0.25 inches) and a wall thickness of 0.089 cm (0.035 inches). The primary discharge ports 50 have a diameter of 0.3175 cm (0.125 inches) while the secondary discharge ports 54 have a diameter of 0.132 cm (0.052 inches). In one embodiment, the evaporator has 45 of the flat tubes 24 in its core or center, which means 11.25 tubes 24 per injector. From the foregoing, it will be readily appreciated that an evaporator made according to the invention obtains excellent distribution of the incoming liquid refrigerant to improve the operating efficiency. The structure used is relatively simple since the injectors can be manufactured from tubes with the discharge orifices drilled therein to the appropriate size. Consequently, a real improvement in efficiency can be obtained at a minimum cost and complexity.

Claims (13)

1. Claims 1. An evaporator comprising a pair of spaced heads, characterized in that it comprises: at least one tube extending between the heads and in fluid communication with each one on one side thereof and defining a plurality of spaced passages or passages for the refrigerant, which extend between the heads; and at least one inlet for the refrigerant inside one of the heads, the inlet has a first hole adapted to be connected to a source of refrigerant to be evaporated and second and third holes directed oppositely to the first orifice, the second The hole is directed away from one of the sides and the third hole is directed towards the other side.
2. 2. The evaporator in accordance with the claim 1, characterized in that the third hole is smaller than the second hole.
3. 3. The evaporator according to claim 1, characterized in that the plurality of passages are defined by a plurality of the tubes, the tubes in the plurality are spaced apart from each other.
4. The evaporator according to claim 3, characterized in that the plurality of tubes have respective tube ends that enter one side of each of the heads.
5. 5. The evaporator according to claim 3, characterized in that each of the tubes further defines a plurality of spaced passages or passages for the refrigerant.
6. 6. The evaporator in accordance with the claim 1, characterized in that the head is elongated and there is a plurality of coolant inlets spaced along the length of the head.
7. 7. The evaporator according to claim 1, characterized in that at least one head is generally tubular.
8. An evaporator comprising a pair of spaced heads, characterized in that: at least one tube extends --- between the heads and in fluid communication with each one on one side thereof and which defines a plurality of spaced passages or passages for the refrigerant, which extend between the heads; and at least one inlet of the refrigerant inside one of the heads, the inlet has a first hole adapted to be connected to a source of refrigerant to be evaporated and a second hole connected to the first hole and located inside the head and which is directed far from one side of the head.
9. The evaporator according to claim 8, characterized in that the inlet includes a third hole inside the head and connected to the first hole, the third hole is directed towards one side of the head.
10. The evaporator according to claim 9, characterized in that the plurality of passages or passages is defined by a plurality of spaced tubes and the second and third orifices are located between two adjacent tubes.
11. 11. An evaporator characterized in that it comprises: an elongated head, a plurality of flat tubes spaced apart and having ends that are received on one side of the head in equally spaced relationship; and an inlet to the head including a plurality of spaced injectors, each adapted to be connected to a common source of refrigerant to be evaporated, each injector includes a discharge orifice directed away from one side of the head.
12. 12. The evaporator according to claim 11, characterized in that the ends extend into the interior of the head and the injectors are located between the ends of pairs of adjacent tubes. The evaporator according to claim 11, characterized in that the discharge orifices are primary discharge orifices, each injector further includes a secondary discharge orifice smaller than the primary discharge orifice and directed towards one side between the pairs ends of adjacent tubes.