Patent Grant
11105558
This invention generally relates to a heat exchanger adapted to be used in a vapor compression system. More specifically, this invention relates to a heat exchanger including at least one baffle arranged to restrict vapor flow, reduce local vapor velocity, isolate liquid leakage and/or trap liquid.
Vapor compression refrigeration has been the most commonly used method for air-conditioning of large buildings or the like. Conventional vapor compression refrigeration systems are typically provided with an evaporator, which is a heat exchanger that allows the refrigerant to evaporate from liquid to vapor while absorbing heat from liquid to be cooled passing through the evaporator. One type of evaporator includes a tube bundle having a plurality of horizontally extending heat transfer tubes through which the liquid to be cooled is circulated, and the tube bundle is housed inside a cylindrical shell. There are several known methods for evaporating the refrigerant in this type of evaporator. In a flooded evaporator, the shell is filled with liquid refrigerant and the heat transfer tubes are immersed in a pool of the liquid refrigerant so that the liquid refrigerant boils and/or evaporates as vapor. In a falling film evaporator, liquid refrigerant is deposited onto exterior surfaces of the heat transfer tubes from above so that a layer or a thin film of the liquid refrigerant is formed along the exterior surfaces of the heat transfer tubes. Heat from walls of the heat transfer tubes is transferred via convection and/or conduction through the liquid film to the vapor-liquid interface where part of the liquid refrigerant evaporates, and thus, heat is removed from the water flowing inside of the heat transfer tubes. The liquid refrigerant that does not evaporate falls vertically from the heat transfer tube at an upper position toward the heat transfer tube at a lower position by force of gravity. There is also a hybrid falling film evaporator, in which the liquid refrigerant is deposited on the exterior surfaces of some of the heat transfer tubes in the tube bundle and the other heat transfer tubes in the tube bundle are immersed in the liquid refrigerant that has been collected at the bottom portion of the shell.
Although the flooded evaporators exhibit high heat transfer performance, the flooded evaporators require a considerable amount of refrigerant because the heat transfer tubes are immersed in a pool of the liquid refrigerant. With the recent development of new and high-cost refrigerant having a much lower global warming potential (such as R1234ze or R1234yf), it is desirable to reduce the refrigerant charge in the evaporator. The main advantage of the falling film evaporators is that the refrigerant charge can be reduced while ensuring good heat transfer performance. Therefore, the falling film evaporators have a significant potential to replace the flooded evaporators in large refrigeration systems. Regardless of the type of evaporator, e.g., flooded, falling film, or hybrid, refrigerant entering the evaporator is distributed to the tube bundle where evaporation of refrigerant occurs due to heating from liquid in the tube bundle. As refrigerant evaporates, refrigerant vapor is present.
It has been discovered that the vapor velocity can become quite high in some evaporators, which increases the likelihood of liquid carry over where liquid droplets enter the inlet of the compressor. This can cause a reduction in chiller efficiency and potentially increase the possibility of erosion of the impeller blade. If low pressure refrigerants such as R1233zd are used, these issues can occur more readily, although these issues can be present regardless of the refrigerant.
Therefore, one object of the present invention is to provide an evaporator that reduces or eliminates spray droplets being sent to the compressor.
One technology used for reducing or eliminating spray droplets is a mist eliminator. Though a mist eliminator can be effective, a mist eliminator may be relatively costly and bulky, taking up much room in the evaporator. In addition, a mist eliminator can cause high pressure drop, which may adversely affect system coefficient of performance (COP). Space requirements can lead to increased shell size and chiller size.
Therefore, another object of the present invention is to provide an evaporator with one or more baffles to redistribute the vapor flow inside of the evaporator. Such baffle(s) can force the flow to equalize and reduce local velocity. Lower velocity allows liquid droplets to settle out of the flow. In addition, such baffle(s) is/are less expensive and take up less space than a mist eliminator.
Another object is to provide a baffle used to even out the vapor flow near the top of the falling film bank by restricting upward vapor flow.
Another object is to provide a baffle used to reduce local vapor velocity between first and second tube passes and remove any liquid droplets by momentum.
Another object is to provide a baffle used to isolate any liquid leakage from the distributor from the bulk vapor flow. Such a baffle is also used to trap and drain any liquid from high speed vapor between the top row of falling film bank and bottom of the distributor.
Yet another object is to provide a baffle used to trap any liquid being dragged up the sides of the shell and direct it onto tubes for evaporation.
On or more of the foregoing objects may be obtained by a heat exchanger in accordance with any one or more of the following aspects. However, the aspects and combinations of aspects mentioned below are merely examples of possible aspects and combinations of aspect disclosed herein that may achieve one or more of the above objects.
A heat exchanger according to a first aspect of the present invention is adapted to be used in a vapor compression system. The heat exchanger includes a shell, refrigerant distributor, tube bundle, and first baffle. The shell has a refrigerant inlet through which at least refrigerant with liquid refrigerant flows and a shell refrigerant vapor outlet. A longitudinal center axis of the shell extends substantially parallel to a horizontal plane. The refrigerant distributor fluidly communicates with the refrigerant inlet and is disposed within the shell. The refrigerant distributor has at least one liquid refrigerant distribution opening that distributes liquid refrigerant. The tube bundle is disposed inside of the shell below the refrigerant distributor. The first baffle extends from a first lateral side of the shell. The first baffle is vertically disposed 5% to 40% of an overall height of the shell above a bottom edge of the shell, and extends laterally inwardly from the first lateral side by a distance not more than 20% of a width of the shell.
In a second aspect, according to the heat exchanger of the first aspect, the first baffle includes a first lateral portion substantially parallel to the horizontal plane, and a first hook portion extending downwardly from the first lateral portion at a location laterally spaced from the first lateral side of the shell.
In a third aspect, according to the heat exchanger of the second aspect, the first hook portion is laterally disposed at an end of the first lateral portion furthest from the first lateral side of the shell.
In a fourth aspect, according to the heat exchanger of the third aspect, the first hook portion is substantially perpendicular to the horizontal plane.
In a fifth aspect, according to the heat exchanger of the third or fourth aspects, the first baffle is constructed of non-permeable material.
In a sixth aspect, according to the heat exchanger of the fifth aspect, the first baffle is constructed of sheet metal.
In a seventh aspect, according to the heat exchanger of the second aspect, the first hook portion extends substantially perpendicular to the horizontal plane.
In an eighth aspect, according to the heat exchanger of the second aspect, the first baffle is constructed of non-permeable material.
In a ninth aspect, according to the heat exchanger of the eighth aspect, the first baffle is constructed of sheet metal.
In a tenth aspect, according to the heat exchanger of any of the first to ninth aspects, the plurality of heat transfer tubes are grouped to form an upper group and a lower group with a pass lane disposed between the upper group and the lower group, and the first baffle is vertically disposed below the pass lane.
In an eleventh aspect, according to the heat exchanger of the tenth aspect, some of the heat transfer tubes in the lower group are flooded by liquid refrigerant, and the first baffle is vertically disposed above a liquid level of the liquid refrigerant.
In a twelfth aspect, according to the heat exchanger of the eleventh aspect, the first baffle is vertically disposed closer to the pass lane than to the liquid level.
In a thirteenth aspect, according to the heat exchanger of any of the tenth to twelfth aspects, the lower group of heat transfer tubes has a lateral width larger than a lateral width of the upper group of heat transfer tubes.
In a fourteenth aspect, according to the heat exchanger of any of the first to ninth aspects, some of the heat transfer tubes are flooded by liquid refrigerant, and the first baffle is vertically disposed above a liquid level of the liquid refrigerant.
In a fifteenth aspect, according to the heat exchanger of any of the first to fourteenth aspects, at least one of the heat transfer tubes is vertically disposed below the first baffle and laterally outwardly of an end of the first baffle furthest from the first lateral side of the shell so that the first baffle vertically overlaps the at least one heat transfer tube as viewed vertically.
In a sixteenth aspect, according to the heat exchanger of any of the first to fifteenth aspects, at least one of the heat transfer tubes is laterally disposed within one tube diameter of the first baffle as measured perpendicularly relative to the longitudinal center axis.
In a seventeenth aspect, according to the heat exchanger of any of the first to sixteenth aspects, a second baffle extends from a second lateral side of the shell. The second baffle is vertically disposed 5% to 40% of the overall height of the shell above the bottom edge of the shell. The second baffle extends laterally inwardly from the second lateral side of the shell by a distance not more than 20% of a width of the shell measured at the second baffle and perpendicularly relative to the longitudinal center axis.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments.
Referring now to the attached drawings which form a part of this original disclosure:
Selected embodiments of the present invention will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
Referring initially to
As shown in
The evaporator 1 is a heat exchanger that removes heat from the liquid to be cooled (in this example, water) passing through the evaporator 1 to lower the temperature of the water as a circulating refrigerant evaporates in the evaporator 1. The refrigerant entering the evaporator 1 is typically in a two-phase gas/liquid state. The refrigerant at least includes liquid refrigerant. The liquid refrigerant evaporates as the vapor refrigerant in the evaporator 1 while absorbing heat from the water.
The low pressure, low temperature vapor refrigerant is discharged from the evaporator 1 and enters the compressor 2 by suction. In the compressor 2, the vapor refrigerant is compressed to the higher pressure, higher temperature vapor. The compressor 2 may be any type of conventional compressor, for example, centrifugal compressor, scroll compressor, reciprocating compressor, screw compressor, etc.
Next, the high temperature, high pressure vapor refrigerant enters the condenser 3, which is another heat exchanger that removes heat from the vapor refrigerant causing it to condense from a gas state to a liquid state. The condenser 3 may be an air-cooled type, a water-cooled type, or any suitable type of condenser. The heat raises the temperature of cooling water or air passing through the condenser 3, and the heat is rejected to outside of the system as being carried by the cooling water or air.
The condensed liquid refrigerant then enters through the expansion device 4 where the refrigerant undergoes an abrupt reduction in pressure. The expansion device 4 may be as simple as an orifice plate or as complicated as an electronic modulating thermal expansion valve. Whether the expansion device 4 is connected to the control unit 5 will depend on whether a controllable expansion device 4 is utilized. The abrupt pressure reduction usually results in partial evaporation of the liquid refrigerant, and thus, the refrigerant entering the evaporator 1 is usually in a two-phase gas/liquid state.
Some examples of refrigerants used in the vapor compression system are hydrofluorocarbon (HFC) based refrigerants, for example, R410A, R407C, and R134a, hydrofluoro olefin (HFO), unsaturated HFC based refrigerant, for example, R1234ze, and R1234yf, and natural refrigerants, for example, R717 and R718. R1234ze, and R1234yf are mid density refrigerants with densities similar to R134a. R450A and R513A are also possible refrigerants. A so-called Low Pressure Refrigerant (LPR) 1233zd is also a suitable type of refrigerant. Low Pressure Refrigerant (LPR) 1233zd is sometimes referred to as Low Density Refrigerant (LDR) because R1233zd has a lower vapor density than the other refrigerants mentioned above. R1233zd has a density lower than R134a, R1234ze, and R1234yf, which are so-called mid density refrigerants. The density being discussed here is vapor density not liquid density because R1233zd has a slightly higher liquid density than R134A. While the embodiment(s) disclosed herein are useful with any type of refrigerant, the embodiment(s) disclosed herein are particularly useful when used with LPR such as 1233zd. This is because a LPR such as R1233zd has a relatively lower vapor density than the other options, which leads to higher velocity vapor flow. Higher velocity vapor flow in a conventional device used with LPR such as R1233zd can lead to liquid carryover as mentioned in the Summary above. While individual refrigerants are mentioned above, it will be apparent to those skilled in the art from this disclosure that a combination refrigerant utilizing any two or more of the above refrigerants may be used. For example, a combined refrigerant including only a portion as R1233zd could be utilized.
It will be apparent to those skilled in the art from this disclosure that conventional compressor, condenser and expansion device may be used respectively as the compressor 2, the condenser 3 and the expansion device 4 in order to carry out the present invention. In other words, the compressor 2, the condenser 3 and the expansion device 4 are conventional components that are well known in the art. Since the compressor 2, the condenser 3 and the expansion device 4 are well known in the art, these structures will not be discussed or illustrated in detail herein. The vapor compression system may include a plurality of evaporators 1, compressors 2 and/or condensers 3.
Referring now to
As best understood from
As shown in
Referring now to
The precise structure of the refrigerant distributor 20 is not critical to the present invention. Therefore, it will be apparent to those skilled in the art from this disclosure that any suitable conventional refrigerant distributor 20 can be used. However, as seen in
Referring now to
As best understood from
In this embodiment, the tube bundle 30 is arranged to form a two-pass system, in which the heat transfer tubes 31 are divided into a supply line group disposed in a lower portion of the tube bundle 30, and a return line group disposed in an upper portion of the tube bundle 30. Thus, the plurality of heat transfer tubes 31 are grouped to form an upper group UG and a lower group LG with a pass lane PL disposed between the upper group UG and the lower group LG as seen in
Therefore, the water flowing inside the heat transfer tubes 31 in the supply line group (lower group LG) is discharged into the water chamber 14a, and redistributed into the heat transfer tubes 31 in the return line group (upper group UG). Outlet ends of the heat transfer tubes 31 in the return line group are fluidly communicated with the water outlet pipe 16 via the outlet water chamber 13b of the connection head member 13. Thus, the water flowing inside the heat transfer tubes 31 in the return line group exits the evaporator 1 through the water outlet pipe 16. In a typical two-pass evaporator, the temperature of the water entering at the water inlet pipe 15 may be about 54 degrees F. (about 12° C.), and the water is cooled to about 44 degrees F. (about 7° C.) when it exits from the water outlet pipe 16.
As shown in
The liquid refrigerant that did not evaporate in the falling film region continues falling downwardly by force of gravity into the flooded region. The flooded region includes the plurality of the heat transfer tubes 31 disposed in a group below the falling film region at the bottom portion of the hub shell 11. For example, the bottom, one, two, three or four rows of tubes 31 can be disposed as part of the flooded region depending on the amount of refrigerant charged in the system. Since the refrigerant entering the supply line group (lower group LG) of the heat transfer tubes 31 may be about 54 degrees F. (about 12° C.), liquid refrigerant in the flooded region may still boil and evaporate.
In this embodiment, a fluid conduit 8 may be fluidly connected to the flooded region within the shell 10. A pump device (not shown) may be connected to the fluid conduit 8 to return the fluid from the bottom of the shell 10 to the compressor 2 or may be branched to the inlet pipe 11b to be supplied back to the refrigerant distributor 20. The pump can be selectively operated when the liquid accumulated in the flooded region reaches a prescribed level to discharge the liquid therefrom to outside of the evaporator 1. In the illustrated embodiment, the fluid conduit 8 is connected to a bottom most point of the flooded region. However, it will be apparent to those skilled in the art from this disclosure that the fluid conduit 8 can be fluidly connected to the flooded region at any location between the bottom most point of the flooded region and a location corresponding to the liquid level LL in the flooded region (e.g., between the bottom most point and the top tier of tubes 31 in the flooded region). Moreover, it will be apparent to those skilled in the art from this disclosure that the pump device (not shown) could instead be an ejector (not shown). In the case, where the pump device is replaced with an ejector, the ejector also receives compressed refrigerant from the compressor 2. The ejector can then mix the compressed refrigerant from the compressor 2 with the liquid received from the flooded region so that a particular oil concentration can be supplied back to the compressor 2. Pumps and ejectors such as those mentioned above are well known in the art and thus, will not be explained or illustrated in further detail herein.
Referring now to
The baffles 40, 50, 60 and 70 are supported by the tube support plates 32.
Specifically, in the illustrated embodiment, each tube support plate 32 has a pair of laterally spaced upper surfaces 34, a pair of laterally spaced intermediate slots 35, a pair of laterally spaced lower slots 36, and a pair of upper slots 37, as best seen in
Referring now to
The upper baffle 40 includes an inner portion 42, an outer portion 44 extending laterally outwardly from the inner portion 42, and a flange portion 46 extending downwardly from the outer edge of the outer portion 44, as best seen in
Referring still to
The inner portion 42 and the outer portion 44 of the upper baffle 40 have a coplanar arrangement substantially parallel to the horizontal plane P. The inner portion 42 and the outer portion 44 of the upper baffle 40 are disposed upwardly from a bottom of the shell 10 between 40% and 70% of an overall height of the shell 10. In the illustrated embodiment, the inner portion 42 and the outer portion 44 of the upper baffle 40 are disposed upwardly from a bottom of the shell 10 about 55% of an overall height of the shell 10. The upper surfaces 34 of the tube support plates 32 are located slightly above the top of the tube bundle 30 at about the same height as the upper baffle 40 as seen in
As best understood from
Still referring to
The function(s) of the upper baffles 40 will now be explained in more detail. Because the upper baffles 40 are located between the tube bundle 30 and the shell refrigerant vapor outlet 12a where refrigerant vapor is sucked out of the shell 10, all of the evaporated vapor must flow through the upper baffles 40. The upper baffles function to even out the vapor flow near the top of the falling film bank by restricting upward vapor flow. The solid area of the inner portion 42 does not allow refrigerant flow to slip off of tube bank, and forces high speed flow at top of tube bundle 30 to mix with lower speed flow in the rest of shell 10. The open area at the outer portion 44 allows for vapor that has been evaporated off of the tube bundle 30 to mix with vapor above the refrigerant distributor 20. Although the illustrated embodiment shows as all the same size openings, different sizes can be provided to direct vapor flow.
As is understood from the above descriptions, the upper baffles 40 are vertically disposed at a top of the tube bundle 30, with the upper baffles 40 extending laterally outwardly from the tube bundle 30 toward a first lateral side LS of the shell 10. In addition, preferably the upper baffles include upper non-permeable portions 42 laterally disposed adjacent to the tube bundle 30 and upper permeable portions 44 laterally disposed outwardly of the upper non-permeable portions 42, with the upper permeable portions 44 being adjacent to the lateral sides LS of the shell 10. In addition, preferably, the upper permeable portions 44 have lateral widths less than 50% of overall lateral widths of the upper baffles 40. Therefore, the upper non-permeable portions have lateral widths larger than the lateral widths of the upper permeable portions, respectively. Also, as mentioned above, the upper baffles 40 are preferably formed of a non-permeable material with holes 48 formed therein to form the upper permeable portions 44. Also, as mentioned above, the upper baffles 40 are preferably vertically disposed at a bottom of the refrigerant distributor 20, and may be attached to a bottom of the refrigerant distributor 20. In the illustrated embodiment, the upper baffles 40 are preferably vertically supported by at least one tube support 32 that supports the tube bundle 30. The upper baffles are vertically disposed 40% to 70% of an overall height of the shell above a bottom edge of the shell.
As mentioned above, in the illustrated embodiment, a pair of upper baffles 40 are preferably present that are mirror images of each other. However, one upper baffle 40 can provide benefits, and thus, the heat exchanger 1 preferably includes at least one upper baffle 40, and does not necessarily require both.
Referring now to
The intermediate baffle 50 includes main portion 52, an outer flange portion 54 extending upwardly from the outer edge of the main portion 52, and reinforcing ribs 56 mounted to the main portion 52. In the illustrated embodiment, the main portion 52 and the outer flange portion 54 are each formed of a rigid sheet/plate material such as metal, which prevents liquid and gas refrigerant from passing therethrough unless holes 58 are formed therein. In addition, in the illustrated embodiment, the main portion 52 and the outer flange portion 54 are integrally formed together as a one-piece unitary member. However, it will be apparent to those skilled in the art from this disclosure that these plates 52 and 54 may be constructed as separate members, which are attached to each other using any conventional technique such as welding. In either case, the main portion 52 is preferably a permeable portion that allows liquid and gas refrigerant to pass therethrough, except at the outer edge thereof. The outer flange portion 54 can be permeable or non-permeable. However, in the illustrated embodiment, the outer flange portion 54 is non-permeable for a more rigid outer portion than if constructed of permeable material. The reinforcing ribs 56 are preferably separate members constructed of the same material as the main portion 52 and are mounted to provide added strength at locations spaced from the tube support plates 32.
Referring still to
As best understood from
The function(s) of the intermediate baffles 50 will now be explained in more detail. As mentioned above, the main portion 52 has the holes 58. Alternatively, the main portion 52 can be a grated or louvered area. In any case, the main portion 58 evens out any high velocity spots and catches droplets and drains them back to liquid pool. Thus, the intermediate baffles 50 are used to reduce local vapor velocity between the first and second tube passes and remove any liquid droplets by momentum. The liquid droplets are stopped (physically) from rising by collision with grid, perforated plate, louvers or the like formed in the main portion 52. While the intermediate baffle 50 can provide some benefit by itself, the intermediate baffle is particularly useful when used in combination with the upper baffle 40. This is because the presence of the upper baffle 40 can lead to high velocity vapor flow and droplets being entrained in such vapor flow. A total opening area of the main portion 52 is preferably between 35%-65% of an overall area. In the illustrated embodiment, the total opening area is about 50%. In addition, the individual opening size with the openings 58 being used is preferably 2-10 millimeters in diameter. The hole size is of the holes 58 are smaller than the hole size of the openings 48 of the upper baffle. In addition, a total area of the holes 58 is preferably a smaller percentage than the total area of the upper baffle 40.
As is understood from the above descriptions, the intermediate baffles 50 are vertically disposed below the upper baffles 40, with the intermediate baffles 50 extending laterally inwardly from the lateral sides LS of the shell. Thus, the intermediate baffles 50 can also be considered lower baffles 50 because they are below the upper baffles 40. Although the intermediate (lower) baffles 50 are below the upper baffles, the intermediate (lower) baffles 50 are preferably vertically disposed above the pass lane PL. In addition, the intermediate (lower) baffles 50 are preferably vertically disposed 20% to 40% of an overall height of the shell 10 above a bottom edge of the shell 10, as best understood from
As mentioned above, in the illustrated embodiment, a pair of intermediate (lower) baffles 50 are preferably present that are mirror images of each other. However, one intermediate (lower) baffle 50 can provide benefits, and thus, the heat exchanger 1 preferably includes at least one intermediate (lower) baffle 50, and does not necessarily require both.
Referring now to
The lower baffle 60 includes a main portion 62 and an inner flange portion 64 extending downwardly from the inner edge of the main portion 62. In the illustrated embodiment, the main portion 62 and the inner flange portion 64 are each formed of a rigid sheet/plate material such as metal, which prevents liquid and gas refrigerant from passing therethrough unless holes are formed therein (none used in the illustrated embodiment). In addition, in the illustrated embodiment, the main portion 62 and the inner flange portion 64 are integrally formed together as a one-piece unitary member. However, it will be apparent to those skilled in the art from this disclosure that these plates 62 and 64 may be constructed as separate members, which are attached to each other using any conventional technique such as welding. In either case, the main portion 62 is preferably a non-permeable portion that prevents liquid and gas refrigerant from passing therethrough. The inner flange portion 64 can be permeable or non-permeable. However, in the illustrated embodiment, the inner flange portion 64 is non-permeable for a more rigid outer portion than if constructed of permeable material.
Referring still to
The function(s) of the lower baffles 60 will now be explained in more detail. The lower baffles 60 are used to deflect toward dry tubes any liquid stream coming from the flooded region on the shell side. Thus, the lower baffles are obstacles for liquid refrigerant to climb up the side of shell. Pooled liquid refrigerant in the flooded region tends to bubble and rise up the side of shell 10. However, the lower baffles 60 are used to trap any liquid refrigerant being dragged up the sides of the shell 10 and direct it onto the refrigerant tubes 31 for evaporation. In the lower group LG of refrigerant tubes 31 some of the tubes 31 are disposed under the lower baffles 60 and adjacent to the lower baffles 60 at locations below the flange portion 64. These tubes 31 perform a function of mist eliminator tubes.
As is understood from the above descriptions, the lower baffles 60 extend from the lateral sides LS of the shell 10, with the lower baffles being vertically disposed 5% to 40% of an overall height of the shell 10 above a bottom edge of the shell 10, and the lower baffles 60 extend laterally inwardly from the lateral sides LS of the shell 10 by a distance not more than 20% of a width of the shell measured at the lower baffles and perpendicularly relative to the longitudinal center axis C. In addition, the lower baffles 60 preferably include lateral (main) portions 62 substantially parallel to the horizontal plane P, and hook (flange) portions 64 extending downwardly from the lateral portions 62 at locations laterally spaced from the lateral sides LS of the shell 10. As seen in
As mentioned above, the lower baffles 60 are each preferably constructed of non-permeable material such as sheet metal. In addition, the lower baffles 60 are preferably vertically disposed below the pass lane PL and above the liquid level LL of the liquid refrigerant. In the illustrated embodiment, the lower baffles 60 are preferably vertically disposed closer to the pass lane PL than to the liquid level LL. In addition, the lower group LG of heat transfer tubes 31 preferably has a lateral width larger than a lateral width of the upper group UG of heat transfer tubes 31. Such an arrangement can aid in mist elimination near the lower baffles 60. Moreover, at least one of the heat transfer tubes 31 is preferably vertically disposed below each of the lower baffles 60 and laterally outwardly of ends of the lower baffles 60 furthest from the lateral sides LS of the shell 10 so that each of the lower baffles 60 vertically overlaps the at least one heat transfer tube as viewed vertically. In addition, at least one of the heat transfer tubes 31 is laterally disposed within one tube diameter of each of the lower baffles as measured perpendicularly relative to the longitudinal center axis C.
As mentioned above, in the illustrated embodiment, a pair of lower baffles 60 are preferably present that are mirror images of each other. However, one lower baffle 60 can provide benefits, and thus, the heat exchanger 1 preferably includes at least one lower baffle 60, and does not necessarily require both.
Referring now to
The upright baffle 70 includes an upper portion 72 and a baffle portion 74 extending downwardly from the outer edge of the upper portion 72. In the illustrated embodiment, the upper portion 72 and the baffle portion 74 are each formed of a rigid sheet/plate material such as metal, which prevents liquid and gas refrigerant from passing therethrough unless holes are formed therein (none used in the illustrated embodiment). In addition, in the illustrated embodiment, the upper portion 72 and the baffle portion 74 are integrally formed together as a one-piece unitary member. However, it will be apparent to those skilled in the art from this disclosure that these plates 72 and 74 may be constructed as separate members, which are attached to each other using any conventional technique such as welding. In either case, the upper portion 72 can be permeable or non-permeable. However, in the illustrated embodiment, the upper portion 72 is non-permeable for a more rigid outer portion than if constructed of permeable material. However, the baffle portion 74 is preferably a non-permeable portion that prevents liquid and gas refrigerant from passing therethrough.
Referring still to
The function(s) of the upright baffles 70 will now be explained in more detail. The upright baffles 70 are used to isolate any liquid leakage from the refrigerant distributor 20 from the bulk vapor flow. Also, the upright baffles are used to trap and drain any liquid refrigerant from high speed vapor refrigerant between the top row of the falling film bank (top of tube bundle 30) and the bottom of the refrigerant distributor 20. Some liquid refrigerant may hang on the bottom of refrigerant distributor 20 and can be drawn out to a side supported by vertical tube support plates 32. However, the upright baffles can assist in preventing (or reducing) such flow from flowing outwardly of the tube bundle 30, e.g., can guide liquid to flow over tube bundle 30. The upright baffles 70 could be mounted to the bottom of refrigerant distributor 20 or to upper baffles 30 if present. Alternatively, the upright baffles 70 could be mounted to the tube support plates 32.
As is understood from the above descriptions, the upright baffles 70 extend downwardly from the refrigerant distributor 20 at a top of the tube bundle 30 to at least partially vertically overlap the top of the tube bundle 30, with the upright baffles being disposed laterally outwardly of the tube bundle 30 toward the lateral sides LS of the shell 10. Preferably, the upright baffles 70 are disposed laterally outwardly of the tube bundle 30 toward the lateral sides LS of the shell 10 by a distance not larger than three times a tube diameter of the heat transfer tubes 31, as best understood from
In addition, the upright baffles 70 preferably vertically overlap the top of the tube bundle 30 by a distance of one to three times the tube diameter, as best understood from
As mentioned above, in the illustrated embodiment, a pair of upright baffles 70 are preferably present that are mirror images of each other. However, one upright baffle 70 can provide benefits, and thus, the heat exchanger 1 preferably includes at least one upright baffle 70, and does not necessarily require both.
Referring now to
Each pair of baffles 40, 50, 60 and 70 has benefits alone, and each individual baffle has benefits alone. However, the baffles 40, 50, 60, and 70 can be used in any combination. For example, one or both upper baffles 40 can be used without any other baffles 50, 60 or 70. Likewise, one or both lower baffles 60 can be used without any other baffles 40, 50 or 70. Likewise, one or both upright baffles 70 can be used without any other baffles 40, 50 or 60. While one or both intermediate baffles 50 can be used without any other baffles 40, 60 or 70, the intermediate baffles 50 are more beneficial when used with the upper baffles 40. The upper baffles 40, the lower baffles 60 and the upright baffles 70 are beneficial alone and when used with any of the other baffles. The baffles 40, 50, 60 and 70 may merely rest within the shell 10, or maybe be tack welded at one or more locations. For example, tack welds at opposite ends of each baffle 40, 50, 60 and 70 can be used to secure the baffles 40, 50, 60 and 70.
Referring now to
In understanding the scope of the present invention, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts. As used herein to describe the above embodiments, the following directional terms “upper”, “lower”, “above”, “downward”, “vertical”, “horizontal”, “below” and “transverse” as well as any other similar directional terms refer to those directions of an evaporator when a longitudinal center axis thereof is oriented substantially horizontally as shown in
While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired. Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. The structures and functions of one embodiment can be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
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