Patent Application
20080302130
The present application is directed generally to an evaporator arrangement. Specifically, the present application is directed to a liquid collection and drainage system to remove liquid refrigerant from vapor refrigerant in an evaporator.
In a refrigeration circuit, refrigerant vapor passes from the evaporator to the compressor. If the refrigerant isn't completely changed to vapor in the evaporator, some liquid refrigerant may be passed on to the compressor as liquid carryover. This liquid carryover can affect both the performance and the life of the compressor.
For example, in a flooded evaporator that has liquid refrigerant introduced in the lower part of the evaporator shell to exchange heat with a fluid passing through a tube bank, liquid droplets may be entrained in the refrigerant vapor flow leaving the evaporator after exchanging heat with the fluid within the tube bank. One approach to solving this problem is to provide a liquid/vapor separator, either internally or externally of the evaporator. While these separators are effective, they add substantial expense to the system.
Another approach to removing liquid refrigerant from the refrigerant vapor in the evaporator has been to provide sufficient vertical space between the top of the tube bank and the suction nozzle at the top of the evaporator shell such that any liquid droplets will be caused to flow downwardly by the force of gravity before they reach the suction nozzle. This approach requires the use of a larger shell, which is costly because of the added materials and space that it requires.
Yet another approach for removing liquid refrigerant has been to provide a so-called “mist eliminator” in the form of a wire mesh, between the top of the tube bank and the compressor suction. Such an eliminator tends to interrupt the flow of the liquid droplets, allowing them to collect on the eliminator and to eventually fall by force of gravity. This approach is somewhat effective in controlling liquid carryover and while it requires less space then the approach described hereinabove, it does require some additional space for the eliminator and also involves additional cost. In addition, the eliminator is recognized as being a passive system in the sense that it simply turns back the droplets, which will tend to be entrained in the flow of refrigerant vapor as before. Furthermore, the eliminator causes pressure drop of the vapor flow resulting in degradation of the performance of the chiller.
Other approaches for removing liquid refrigerant include providing a baffle above the tube banks for interrupting and collecting the upward flow of liquid refrigerant droplets that would otherwise tend to flow to the compressor along with the refrigerant vapor. Heat may be added to the baffle to cause an evaporation of the liquid droplets such that the resulting vapor passes to the compressor. However, this approach does not offer an effective drainage of the liquid collected by the baffle.
Intended advantages of the methods and/or systems satisfy one or more of the needs or provide other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the claims, regardless of whether they accomplish one or more of the aforementioned needs.
One embodiment is directed to a liquid collection and drainage system to remove liquid refrigerant from refrigerant vapor in an evaporator including a baffle having an inside surface to be disposed adjacent a suction inlet of the evaporator and an outside surface to be disposed adjacent a refrigerant pool of the evaporator. The system also includes a mesh pad and a drainage pipe. The mesh pad is disposed adjacent to the inside surface of the baffle and is configured to trap liquid refrigerant. The drainage pipe has a drain hole at one end and is configured to extend along the baffle to permit liquid refrigerant to flow to the drain hole. Liquid refrigerant is trapped by the mesh pad and collected in the drainage pipe to flow to the drain hole for return to a refrigerant pool.
Another embodiment is directed to an evaporator with a drainage system to remove liquid refrigerant from refrigerant vapor including a housing having an upper portion and a lower portion, a tube bank disposed in the lower portion of the housing and a drainage device disposed in the upper portion of the housing. The drainage device includes a suction baffle having an inside surface to be disposed adjacent a suction inlet of the evaporator and an outside surface to be disposed adjacent the tube bank. The drainage device also includes a mesh pad configured and disposed adjacent the inside surface of the suction baffle to trap liquid refrigerant. Further, the drainage device has a tapered pipe configured with a drain hole at one end and extending along the bottom of the suction baffle. Liquid refrigerant is trapped by the mesh pad and flows into the tapered pipe upon operation, where the trapped liquid refrigerant builds a liquid column and flows toward the drain hole.
One advantage is the reduction in liquid carryover into the compressor.
Another advantage is decreased power consumption and higher system efficiency compared to a system with liquid carryover.
Another advantage is the elimination of costly and large devices or systems to remove the liquid carryover.
Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims.
The condensed liquid refrigerant delivered to evaporator 12 enters into a heat exchange relationship with a fluid, e.g., water, brine or ethylene glycol, and undergoes a phase change to a refrigerant vapor as a result of the heat exchange relationship with the fluid. The vapor refrigerant in evaporator 12 exits evaporator 12 and returns to compressor 13 by a suction line to complete the cycle. It is to be understood that any suitable configuration of condenser 10 can be used in system 14, provided that the appropriate phase change of the refrigerant in condenser 10 is obtained. Refrigeration system 14 can include many other features that are not shown in
Now referring to
Referring now to
Mesh pad 22 is a thin layer of steel, plastic, or other material suitable for absorbing refrigerant liquid that is separated from the refrigerant vapor by suction baffle 16. Mesh pad 22 is secured in baffle 16 by use of retainers such as clips, rods and other suitable fasteners. In addition, suction baffle 16 may have a grooved surface that is also constructed of any material suitable for collecting liquid refrigerant. The grooves may be formed by manufacturing them with the baffle as one unitary piece. The grooves on the surface of suction baffle 16 are protrusions that allow any liquid in the vapor to collect. As the liquid droplets collect on the grooves and form droplets, the droplets follow the path of the grooves to the bottom of the baffle where the droplets fall into tapered pipe 24. The protrusions of the grooves form a path extending downward to tapered pipe 24 so that the droplets collected thereon can flow easily to pipe 24 and on to drain hole 26.
Tapered pipe 24 is shaped such that it is sized from a larger diameter end 32 to a smaller diameter end 34 as shown in
It should be understood that the application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the phraseology and terminology employed herein is for the purpose of description only and should not be regarded as limiting.
While the exemplary embodiments illustrated in the figures and described herein are presently preferred, it should be understood that these embodiments are offered by way of example only. Accordingly, the present application is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the appended claims. The order or sequence of any processes or method steps may be varied or re-sequenced according to alternative embodiments.
It is important to note that the construction and arrangement of the drainage mechanism as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present application. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present application.
