Dehumidification system having a coil split subcooler for removing moisture from an air flow and methods thereof

Abstract

A dehumidification system is provided that includes a coil split subcooler having a plurality of splits that each include at least one circuit for removing moisture from an air flow. In addition, a system and method for modulating the capacity of a subcooler are provided whereby the rate in which moisture is removed from an air flow can be optimized.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention generally relates to a system and method for removing moisture from air, and more particularly to a coil split subcooler and methods for optimizing the rate in which moisture can be removed from an air flow as the relative humidity of the air flow varies.

[0003] 2. Background Art

[0004] In the drying of articles having waterborne coatings, it is often necessary for a continuous or re-circulated air flow to be provided. To optimize the drying process, such an air flow must be continually dehumidified and/or filtered. Accordingly, a drying booth or similar apparatus is often employed that includes a dehumidification system and/or a filtration system. Specifically, a product coated with a waterborne coating, such as an automobile component, is positioned in the drying booth and then exposed to an air flow for drying the coating. After exposure to the coated product, however, the air flow will contain increased levels of moisture and particulates. To remove the accumulated moisture and particulates, the air flow can be directed through a dehumidification system and a filtration system. Once the moisture and particulates have been removed, the air flow can then be re-circulated to the coated product to continue drying the waterborne coating. Such drying systems are shown in U.S. Pat. Nos. 5,554,416, 5,709,038, and 5, 5,718,061, all to Scheufler et al. and all of which are herein incorporated by reference.

[0005] Standard dehumidification systems include an evaporator, a compressor, a condenser, and an expander. Within the system is refrigerant, such as R-22, which cycles between the components. An air flow to be dehumidified will first be directed over the evaporator, as refrigerant is traveling therethrough in a cooled or liquid form. Then, as the warm, moisture-containing air contacts the evaporator, the heat therein is transferred to the cooled refrigerant. This heat exchange cools the air and causes the moisture to condense out, and may at least partially vaporize the refrigerant. Next, the refrigerant will travel to the compressor, where it is subjected to increased pressure, and then directed to the condenser where the cooled, moisture-reduced air flow will contact the condenser and cause the refrigerant to be cooled back to a liquid form. Although this will increase the temperature of the air flow, the air will remain dry. Lastly, the air exits the system as a dehumidified air flow and the refrigerant is directed to the expander where it is further cooled and then directed back to the evaporator for another cycle.

[0006] Problems arise during dehumidification when the moisture cannot be removed from the air flow at acceptable rates. This often occurs when the air flow has a reduced level of moisture or low relative humidity because the less moisture air has, the slower the moisture can be removed. In particular, standard dehumidification systems can only remove approximately 0-2 pounds of moisture per hour from air when the relative humidity of the air is less than approximately 35%. Such a low rate prevents the efficient operation of industrial processes and accordingly, results in increased expenses to the user(s).

[0007] One way to alleviate such problems it to position a subcooler in the dehumidification system, between the condenser and expander. The role of the subcooler is to further cool the refrigerant prior to its entry into the evaporator. In particular, the air flow will first contact the evaporator, thus cooling the air flow. Then, the cooled air flow will contact the subcooler, causing the refrigerant to be cooled. The refrigerant is then directed to the expander where it is further cooled. Thus, the refrigerant is subjected to two additional cooling steps after exiting the condenser. The cooler the refrigerant is as it enters and flows through the evaporator, the quicker any moisture will be removed from the air flow. For example, by subcooling the refrigerant by approximately 15° F., the performance of the evaporator will increase by approximately 11%.

[0008] Related subcooler arrangements, however, all fail to provide for the modulation of the subcooler's capacity. In particular, related embodiments fail to teach subcoolers having multiple inlets that can be controlled individually as the relative humidity of the air flow varies. Such embodiments give a user far less control over their respective systems because they do not allow a user to modulate the capacity of the subcooler so that the rate in which moisture is removed from the air flow can be optimized. For example, when an incoming air flow has a decreasing or lower relative humidity (less than about 40%-45%), a user should be able to increase the capacity of the subcooler so that more subcooled refrigerant can be provided to the evaporator. In contrast, where the air flow has an increasing or high relative humidity, a user should be able to decrease the subcooler capacity to prevent the freezing of the evaporator coil.

[0009] U.S. Pat. No. 4,984,433 to Worthington attempts to alleviate some of these problems by providing numerous subcooling coils (subcoolers) in parallel. However, when providing a plurality of subcoolers in parallel, not only do the costs to the user multiply, but a disparity in subcooler capacity is created, as will be described in further detail below. Even if a user superimposed a plurality of parallel subcoolers in an attempt to simulate an intertwined coil arrangement, the efficiency of the system would be compromised. Namely, the increased air friction created with the superimposition of the coils would increase the static pressure of the system, thus, reducing system efficiency.

[0010] Therefore, there exists a need for a single subcooler unit whose capacity can be modulated so as to optimize the removal rate of moisture from an air flow as the humidity of the air flow changes. Moreover, there exists the need for a subcooler having such characteristics to have uniform subcooling capacity so that the efficiency of the subcooling operation and of the evaporator can be maximized.

SUMMARY OF THE INVENTION

[0011] The present invention overcomes the deficiencies of the related art by providing a dehumidification system including a coil split subcooler for removing moisture from air and methods thereof. More particularly, the present invention provides a subcooler having multiple splits each having multiple circuits so as to provide for optimal capacity modulation of the subcooler. Specifically, the present invention allows for the capacity of the subcooler to be modulated as the relative humidity of the air being dehumidified changes. In addition, the present invention provides a subcooler having uniform subcooling capacity.

[0012] According to a first aspect of the present invention, a dehumidification system is provided that includes: (1) a subcooler having a plurality of splits, wherein each split includes at least one circuit.

[0013] According to a second aspect of the present invention, a dehumidification system that receives a humidified air flow and outputs a dehumidified air flow is provided that includes: (1) a subcooler having a plurality of splits, wherein each split includes at least one circuit; (2) a mechanism for activating and de-activating each split; (3) a system for measuring humidity of the humidified air flow; and (4) a system for controlling an amount of refrigerant passing through each split based on measured humidity.

[0014] According to a third aspect of the present invention, an air dehumidification and drying system is provided that includes: (1) a drying booth for drying waterborne coatings; and (2) a dehumidification system, operatively attached to the drying booth, wherein the dehumidification system comprises a subcooler having a plurality of splits, wherein each split includes at least one circuit.

[0015] According to a fourth aspect of the present invention, a method of modulating the capacity of a subcooler is provided that includes the steps of: (1) providing a dehumidification system that includes a subcooler having a plurality of splits that each include at least one circuit; (2) directing an air flow through the dehumidification system; (3) measuring a humidity value of the air flow; and (4) controlling the splits based on the humidity value.

[0016] According to a fifth aspect of the present invention, a method of removing moisture from air is provided that includes the steps of: (1) providing a dehumidification system including a subcooler having a plurality of splits that each include at least one circuit; (2) flowing non-vaporous refrigerant from a condenser to the subcooler; (3) modulating the capacity of the subcooler by controlling the splits; (4) flowing the refrigerant from the subcooler to an expander; (5) flowing the refrigerant from the expander to an evaporator; and (6) removing moisture from an air flow by directing the air flow over the evaporator.

[0017] According to a sixth aspect of the present invention, a method for drying waterborne coatings is provided that includes the steps of: (1) providing an article coated with a waterborne coating; (2) directing an air flow over the coated article; (3) removing moisture from the air flow by directing the air flow to a dehumidification system having a subcooler including a plurality of splits, wherein each split includes at least one circuit.

[0018] It is therefore an advantage of the present invention to provide a dehumidification system having a coil split subcooler for removing moisture from air and methods therefor. It is a further advantage of the present invention to provide a system and method for modulating the capacity of a subcooler so as to optimize the moisture removal rate of an air flow whereby the capacity of the subcooler can be varied based upon the relative humidity level of the air flow. Moreover, it is an advantage of the present invention to provide a system and method for efficiently drying waterborne coatings.

[0019] The preferred embodiment of the present invention is designed to solve the problems herein described and other problems not discussed, which are discoverable by a skilled artisan.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] These and other features and advantages of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings in which:

[0021] FIG. 1 is a block diagram of a dehumidification system, according to the present invention;

[0022] FIG. 2 is a cross-sectional view of a first embodiment subcooler at full load, according to the present invention;

[0023] FIG. 3 is a cross-sectional view of the subcooler of FIG. 2 at partial load, according to the present invention;

[0024] FIG. 4 is a cross-sectional view of a second embodiment subcooler at full load, according to the present invention;

[0025] FIG. 5 is a cross-sectional view of the subcooler of FIG. 4 at partial load, according to the present invention;

[0026] FIG. 6 is a cross-sectional view of a third embodiment subcooler at full load, according to the present invention;

[0027] FIG. 7 is a cross-sectional view of the subcooler of FIG. 6 at partial load, according to the present invention;

[0028] FIG. 8 is schematic of a dehumidification system, according to the present invention;

[0029] FIG. 9 is a cross-sectional view of a related art subcooler;

[0030] FIG. 10 is a first graph depicting moisture removal rate versus relative humidity;

[0031] FIG. 11 is a second graph depicting moisture removal rate versus relative humidity;

[0032] FIG. 12 is a third graph depicting moisture removal rate versus relative humidity;

[0033] FIG. 13 is an illustration of a filtration and dehumidification system, according to the present invention;

[0034] FIG. 14 is an illustration of the system of FIG. 13 in conjunction with a drying booth, according to the present invention;

[0035] FIG. 15 is a flowchart of a first method, according to the present invention;

[0036] FIG. 16 is a flowchart of a second method, according to the present invention; and

[0037] FIG. 17 is a flowchart of a third method, according to the present invention.

[0038] It is noted that the drawings of the invention are not to scale. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. The drawings are intended to depict only typical embodiments of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

[0039] Referring to FIG. 1, a block diagram of the present invention dehumidification system 10 is depicted. The dehumidification system 10 includes an evaporator 20, a compressor 22, a condenser 12, a receiver 14, a coil split subcooler 16, and an expander 18. Expander is preferably a valve, however, it should be understood that other devices could be implemented. Moisture is removed from an air flow 23 by directing the flow 23 through the dehumidification system 10 in the direction shown by arrow 25. Refrigerant 15, such as R-22, is stored within the system 10 and is directed or flows from component to component as will be described in detail below. Although a specific refrigerant 15 has been cited, it should be appreciated that any known refrigerant can suffice.

[0040] Problems exist in removing moisture from the air flow 23 as the relative humidity of the air flow 23 decreases. In particular, as the moisture level of the air decreases, the more difficult and time consuming it becomes to remove the moisture therefrom. Thus, the time the system 10 will have to operate increases and overall efficiency of the process decreases. To alleviate such problems a subcooler 16 is utilized to further reduce the temperature of the refrigerant 15 prior to its entry in the evaporator 20 and prevent the formation of flash gas through the expander 18. By reducing the temperature of the refrigerant 15 prior to its entry into the evaporator 20, the net refrigeration effect of the evaporator 20 will be improved, thus, keeping the rate at which moisture is removed from the air flow 23 at desired levels.

[0041] FIG. 2 shows a cross-sectional view of a first coil split subcooler subcooler 17 according to the present invention, at full load. As can be seen, the subcooler 17 is disposed between the receiver 14 and the expander 18. Generally, the subcooler 17 comprises a first split 24A, a second split 24B, valves 36A and 36B, rows 26A and 26B, tubes 30, and outlet 28. Originating from each split 24A and 24B are circuits 32A-32B, and 34A-34B, respectively. A circuit is the path that refrigerant follows from the splits 24A and 24B to the outlet 28. The double lines in the circuits, between the tubes 30, represent return bends 31 between the ends of the tubes 30. This embodiment is generally referred to as an intertwined coil split subcooler and is distinctly advantageous over other embodiments such as the row split subcooler, which will be contrasted in more detail below. It should also be appreciated that the number of splits, circuits, rows, and tubes may vary depending on the needs of the user. For example, a subcooler having more than 2 splits can be implemented. In addition, it should be understood that although the valves 36A and 36B are preferably solenoid valves, other equivalent variations exist.

[0042] In use, refrigerant 15 is directed from receiver 14 to the splits 24A and 24B, whose operation is controlled by valves 36A and 36B. Once within the splits 24A and 24B, the refrigerant 15 flows through the tubes 30 of the subcooler 17 and to the outlet 28, in the paths demonstrated by the circuits 32A, 32B, 34A, and 34B. In particular, the refrigerant 15 will enter the tubes 30 of the first row 26A and flow along the length of the subcooler 17 (into the page). The refrigerant 15 will then proceed around the return bend 31 and travel through the tubes 30 of the second row 26B (out of the page). Once through the second row 26B of tubes 30, the refrigerant 15 will then flow through the outlet 28 and to the expander 18 in a cooled form. This is known as a two pass flow because the refrigerant 15 makes two passes through the tubes of the subcooler 17. One pass is through a tube 30 in row 26A and a second pass is through the tube 30 in row 26B. By utilizing a subcooler at full load, such as that described in FIG. 2, the capacity of the subcooler will be at least approximately 30,000 BTU/HR while the capacity (power) of the corresponding evaporator will be at least approximately 60,000 BTU/HR.

[0043] It should be appreciated that although a specific pattern for the passes has been described, such description is for illustration purposes only. For example, the first pass for the refrigerant 15 may be along a tube 30 in row 26A “out of the page” and the second may be along a tube 30 in row 26B “into the page.”

[0044] FIG. 3 shows the subcooler 17 of FIG. 2 at partial load. Specifically, at partial load, only one of the splits 24A will be activated. Thus, the refrigerant 15 will have half the number of circuits 32A and 32B to flow along. It should be appreciated that although split 24A is shown as being active, a user could activate split 24B in lieu thereof. At partial load, the split that is active will perform at a capacity of approximately 18,000 BTU/HR or about 60% of the total capacity of the subcooler 17 at full load. This output is irrespective of which split 24A or 24B is active.

[0045] The adjustability of the subcooler 17 allows a user to more accurately gauge the level of subcooling to which the refrigerant 15 is subjected. Specifically, under previous devices, only one split and/or one circuit subcoolers are provided. Such devices hamper a user's ability to alter the level of subcooling. This is an issue where the relative humidity of the air flow 23 is high. For example, if the relative humidity is above approximately 70%, and the user subcools the refrigerant 15 too much, the tubes of the evaporator 20 will freeze. In contrast, where the relative humidity of the air flow 23 is low, and the user fails to adequately subcooler the refrigerant 15, the rate at which moisture is removed from the air flow 23 will be drastically slow, if at all. The intertwined coil split subcooler arrangement shown throughout the Figures allows for optimal adjustability of the subcooler by a user. By engaging both splits, the refrigerant 15 can be subcooled to a lower temperature. For example, by activating one split 24A or 24B of the subcooler 17, the refrigerant 15 can be subcooled by approximately 30° F. Similarly, by activating bother splits 24A and 24B, the refrigerant 15 can be subcooled by approximately 50° F.

[0046] Referring now to FIGS. 4 and 5, a second subcooler 19 according to the present invention is shown. Specifically, this embodiment has the same basic components as the 5 ton subcooler 17, such as two splits 25A and 25B, tubes 30, rows 27A and 27B, and outlet 29. However, the number of tubes 30 as well as the number of resulting circuits will increase. As shown in FIG. 4, the subcooler 19 is at full load and includes 6 circuits per split for a total of 12 circuits 33A-33F and 35A-35F. The refrigerant 15 will travel through the subcooler 19 in the same manner as described for the subcooler 17 described above. In particular, the refrigerant 15 will flow from the splits 25A and 25B along the circuits 33A-33F and 35A-35F, make two passes for each circuit through the tubes 30, and flow through the outlet 29. By utilizing subcooler 19 of FIG. 4, the subcooling capacity will increase to at least approximately 60,000 BTU/HR, while its corresponding evaporator will perform at a capacity of at least about 120,000 BTU/HR.

[0047] FIG. 5 shows the subcooler 19 of FIG. 4 at partial load. In particular, only one split 25A and its corresponding circuits 33A-33F are active. Similar to the subcooler 17 of FIG. 3, either split could be activated. Moreover, at partial load, the active split is capable of operating at least about 36,000 BTU/HR regardless of which split 25A or 25B is active.

[0048] It should be understood that although a precise number of splits, tubes and circuits have been set forth for the preferred embodiments of the subcooler 17 and 19 of the present invention, the quantity may still vary. Specifically, FIGS. 6 and 7 illustrate an additional embodiment for the subcooler 16. As shown, the subcooler 21 of FIG. 6 is at full load and includes four rows with 8 tubes in each row. Similarly, there are two splits 45A and 45B with a total of eight circuits (four per split) 41A-41D and 43A-43D. Distinctions between this embodiment and those shown in FIGS. 2-5 include not only the number of circuits 41A-41D and 43A-43D and tubes 30, but also the number of passes the refrigerant 15 makes through the subcooler 21. In particular, the refrigerant 15 in each circuit will make a total of four passes through the tubes 30, as opposed to two in the previous embodiments. FIG. 7 shows the subcooler 21 of FIG. 6 at partial load.

[0049] It should be understood the subcoolers 21 of FIGS. 6 and 7 operate in the same manner as described above for the subcoolers 17 and 19 of FIGS. 2-5. Specifically, the refrigerant 15 will flow through the circuits and tubes in the same manner, only the refrigerant 15 will make more passes in the subcooler 21 of FIGS. 6 and 7.

[0050] Regardless of which embodiment is implemented by the user, the subcooler 16 may be constructed with the appropriate number of circuits and passes for the particular system in which it is being used. For example, if a subcooler is constructed with too many passes, the circuit length becomes elongated causing refrigerant 15 side pressure drop to increase. As this occurs, the liquid refrigerant 15 may form flash gas. In contrast, if the circuit length is decreased, the refrigerant 15 may not be given the requisite time within the subcooler 16 to be cooled to the appropriate levels. Accordingly, the number of passes and circuits needs to be carefully balanced.

[0051] Referring now to FIG. 8, a schematic of the dehumidification system 10 of the present invention is set forth. As shown by the block diagram of FIG. 1, the dehumidification system 10 of the present invention includes an evaporator 20, a compressor 22, a condenser 12, a receiver 14, and a coil split subcooler 16. As depicted, the four row subcooler 21 of FIG. 6 is utilized. However, it should be appreciated that the subcoolers 17, 19, and 21 of FIGS. 2-5 and 7 could be substituted therefor. In addition, the dehumidification system 10 can include a remote condenser 38, which allows the condenser 12 to be bypassed if the continual operation thereof limits the system's effectiveness.

[0052] As indicated above, the refrigerant 15 will flow from the receiver 14 to the subcooler 16. Typically, the refrigerant is at a temperature in the range of approximately 100° F.-120° F. and preferably about 110° F., and has a pressure of about 226 PSIG when it leaves the receiver 14. Once within the subcooler 16, the refrigerant 15 is cooled to a temperature in the range of approximately 70° F.-80° F. and about preferably 75° F. Once cooled to the desired level, the refrigerant 15 is then directed to the expander 18, where the pressure is reduced to approximately 59 PSIG. This pressure drop prevents the refrigerant 15 from forming flash gas by further cooling the same to a temperature in the range of approximately 30° F.-40° F., and preferably about 35° F.-37° F. From the expander 18, the refrigerant 15 will flow to the evaporator 20.

[0053] Once inside the evaporator 20, the refrigerant 15 will be indirectly contacted by the warm, moisture-containing air flow 23. As the air flow 23 contacts the evaporator 20, the heat therein is transferred to the refrigerant 15, thus causing the refrigerant 15 to at least partially evaporate and the moisture in the air to condense out. As the refrigerant 15 exits the evaporator, its temperature is in the range of approximately 45° F.-55° F., and is preferably about 50° F. The refrigerant 15 is then directed to the compressor 22, where its pressure is increased to approximately 226 PSIG and its temperature is increased to about 140° F.-150° F. (preferably about 145° F.), and is then directed to the condenser 12. As the vaporous refrigerant 15 enters the condenser 12, it is contacted by the cooled air flow 23, which cools the refrigerant 15 to a temperature in the range of about 100° F.-120° F. (preferably 110° F.). This reduction in temperature of the refrigerant 15 causes the refrigerant 15 to at least partially convert back to a liquid form. The slightly warmed, moisture-reduced air flow 23 then exits the dehumidification system 10 and the refrigerant 15 is directed back to the receiver 14 for another cycle.

[0054] Those of ordinary skill in the art will realize that the air flow 23 is what contacts both the subcooler 16 and cools the refrigerant 15 therein, after the air flow 23 has been cooled by the refrigerant 15 in the evaporator 20. Accordingly, it should be understood that the cooled air flow 23 cools the refrigerant 15 at least twice in the dehumidification system 10. Specifically, the cooled air flow 23 cools the refrigerant 15 first as it flows through the subcooler 16 and a second time as it flows through the condenser 12.

[0055] The activation or de-activation of the splits 45A and 45B of the subcooler 16 is controlled by the humidity of the incoming air flow 23. Specifically, as the humidity of the incoming air decreases to fall below a pre-determined level or value, one or more splits will be activated. In contrast, as the humidity rises above a pre-determined value or level, the one or more splits may be de-activated. This allows a user to modulate the capacity of the subcooler as the humidity of the air flow 23 changes.

[0056] Previously, a user was without means to alter the capacity of the subcooler based on the relative humidity of an air flow. This lead to poor moisture removal rates of the air flow 23 at lower relative humidity levels. Specifically, as the relative humidity of the air flow 23 is lowered, the rate at which moisture can be removed will decrease. Accordingly, by subcooling the refrigerant 15, the moisture removal rates can be maintained at acceptable levels. However, as the relative humidity of the air flow 23 increases, one or more splits can be de-activated to avoid an over-cooling of the refrigerant 15. If over-cooling is not prevented, evaporator 20 may freeze. The system by which the splits are controlled includes a humidity sensor(s) that communicates with the valves 36A and 36B of the subcooler 16 to activate or de-activate one or more splits, as will be described in more detail below.

[0057] In related embodiments, such as U.S. Pat. No. 4,984,433 to Worthington, a plurality of subcoolers 38-44 are disposed in parallel, normal to an air flow. The desired results are to increase the subcooling of refrigerant. However, such an embodiment fails to achieve the optimal subcooling effect of the present invention. In contrast, when employing the embodiment of Worthington, a row split subcooling coil is simulated, as shown in FIG. 9. In viewing FIG. 9, it can be seen that each circuit 53A-53D and 55A-55D traverses only one set of rows 59A-59B or 59C-59D. When compared to the full load coil split subcooler of the present invention, as shown in FIG. 6, it can be seen that each circuit traverses all rows (an intertwined arrangement). Thus, increasing the surface area of refrigerant through the subcooler.

[0058] Problems associated with Worthington's arrangement include those described above, namely, that the subsequent subcoolers will not give an equal heat transfer capacity due to the difference in temperature gradient between the subcoolers and the air flow. Specifically, if two parallel subcoolers are provided at full load, the second subcooler will be able to produce only about 40% of its total capacity. For example, if Worthington provides two 10,000 BTU/HR capacity subcoolers at full load, only 14,000 BTU/HR total will be produced. The difference in temperature gradient is created when the air flow is heated upon contact with the first subcooler and, therefore, is rendered closer in temperature to the refrigerant in the second subcooler In contrast, each individual split of the subcooler of the present invention is capable of producing 100% of its total subcooling capacity at full load. For example, the two splits of a 20,000 BTU/HR coil split subcooler will each produce their maximum capacity of 10,000 BTU/HR. Moreover, at partial load, the one active split can produce approximately 60% of its total capacity. This is due to residual heat conducted by the subcooler's fins surrounding the inactive tubes. For example, the active split of a coil split subcooler having 20,000 BTU/HR capacity will produce approximately 12,000 BTU/HR capacity at partial load.

[0059] FIGS. 10-12 depict graphs of moisture removal rates versus relative humidity. Referring first to FIG. 10, it can be seen that at approximately 35% relative humidity, a dehumidifier that lacks a subcooler will remove approximately 0 pounds of moisture per hour from an air flow. This inability to remove moisture at lower humidities cripples the efficient operation of drying processes. In contrast, a 5 ton or 60,000 BTU/HR capacity dehumidifier having a coil split subcooler will remove approximately 8 pounds of moisture per hour at part load (one split active) and approximately 12 pounds of moisture per hour at full load (both splits active). Thus, by utilizing a coil split subcooler, drying processes can maintain desired efficiency levels.

[0060] Similarly, FIGS. 11 and 12 depict graphs of moisture removal rate versus relative humidity that compare a 5 ton or 60,000 BTU/HR capacity dehumidifier having a coil split subcooler to two parallel subcoolers. Referring to the FIG. 11 both embodiments are shown at part load. Although a dehumidifier having two parallel subcoolers will remove moisture more efficiently than a dehumidifier lacking a subcooler (as shown in FIG. 10), a coil split subcooler will perform better than either by yielding the highest moisture removal rates at any relative humidity. The same result holds true when the coil split subcooler and two parallel subcoolers are at full load, as shown in FIG. 12.

[0061] FIG. 13 shows one possible embodiment for a combination dehumidification and filtration system 200. As shown, an air flow 212 enters the system 201 and passes through arrestor 202 and secondary pre-filter 204. The air flow 212 then travels in the direction of arrow 211 and flows past sensor array 220. As the air flow 212 passes the sensors, humidity sensor 226 measures the relative humidity thereof. The air flow 212 then continues through the primary pre-filter 232, the high efficiency particulate air filter (HEPA) 234, the gas separation filter 238, and the blower impeller 242. The multiple filtration steps will remove any particulates from the air flow 212. After flowing through the various filters, the air flow 212 then passes through the dehumidification system 10. Included in the dehumidification system 10 are the components described above, namely, evaporator 20, condenser 12, coil split subcooler 16 (splits and circuits not shown), receiver 14, expander 18, and compressor 22. A more specific description of the filtration system 201, its components, and the air flow therethrough is given in U.S. Pat. No. 5,554,416. Moreover, although a specific layout has been set forth, such layout is for illustration purposes only. For example, the components may be physically re-arranged. In addition, the subcooler 16 may be any multiple split, circuited subcooler, such as those shown in FIGS. 2-7.

[0062] The relative humidity value measured by the humidity sensor 26 is transmitted to the valves on the subcooler 16 and is used to activate or de-activate one or more splits. For example, if the humidity value measured by the humidity sensor 226 is below a pre-determined level, one or more splits will be activated. In contrast, if the measured relative humidity value is above a predetermined value, one or more splits will be de-activated. The goal is to optimize the moisture removal rate for the air flow 212 without compromising the performance of the dehumidification system 10. In particular, at higher humidities (approximately at least 70%) a user may only have to activate one or no splits and still maintain acceptable moisture removal rates. However, if a user attempts to activate too many splits at a higher relative humidity the evaporator 20 may freeze. Similarly, a user may choose to engage both splits at lower humidities (lower than approximately 40%) so that moisture removal rates can be maintained above the minimum acceptable levels.

[0063] It should be appreciated that the specific humidity values cited herein are for illustration purposes only and are not intended to be limiting. For example, the relative humidities in which the splits are activated or de-activated will vary depending on the particular user and his/her needs. It should also be understood that the control of the valves is based upon the relative humidity value measured by the humidity sensor 226 can be accomplished by any known means. For example, the humidity value can be electrically or optically transmitted from the sensor 226 to a control system (such as a computer), which will control the valves based on a pre-determined relative humidity value.

[0064] FIG. 14 shows the dehumidification and filtration system 200 of FIG. 13 in conjunction with a drying booth 270. As depicted, an article/product 266 coated with a waterborne coating is positioned within the drying booth 270 and exposed to an air flow 212. The air flow will contact the coated article and enter the dehumidification and filtration system 200, as described above. After completing the dehumidification step, the air flow is then returned to the drying booth 270 to make another pass at the coated article. Thus, the air flow 212 is re-circulated or continually recycled until the coated article is dry, i.e. the moisture has been removed from the coating. In order to achieve efficient drying, moisture removal rates must be maintained above a minimally acceptable level. As the article is nearly dry, the relative humidity of the air flow 212 will decreases, making it difficult for ordinary dehumidification systems to remove the moisture therefrom. Accordingly, systems without a coil split subcooler will have to make numerous additional passes or re-circulations before the coated article 266 is dried.

[0065] FIGS. 15-17 depict flowcharts of various methods according to the present invention. Referring first to FIG. 15, the first step 302 in the method 300 is to provide a dehumidification system that includes a subcooler having a plurality of splits that each include at least one circuit. The next step 304 is to direct an air flow through the dehumidification system. The third step 306 is to measure a humidity value of the air flow. The last step 308 of the method 300 is to control the splits based on the humidity value.

[0066] FIG. 16, depicts a second method 310, which includes a first step 312 of providing a dehumidification system including a subcooler having a plurality of splits that each include at least one circuit. The second step 314 is to flow non-vaporous refrigerant from a condenser to the subcooler. The third step 316 is to modulate the capacity of the subcooler by controlling the splits. The fourth step 318 is to flow the refrigerant from the subcooler to an expander. The fifth step of the method 310 is to flow the refrigerant from the expander to an evaporator. The final step 322 is to remove moisture from an air flow by directing the air flow over the evaporator.

[0067] Lastly, FIG. 17 depicts a third method according to the present invention. In particular, the first step 326 of the method 324 is to provide an article coated with a waterborne coating. The second step 328 is to direct an air flow over the coated article. The third step is to remove moisture from the air flow by directing the air flow to a dehumidification system having a subcooler including a plurality of splits, wherein each split includes at least one circuit.

[0068] The foregoing description of the preferred embodiments of this invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously, many modifications and variations are possible. Such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims.

Claims

1. A dehumidification system comprising:

a subcooler having a plurality of splits, wherein each split includes at least one circuit.

2. The system of

claim 1, wherein the subcooler comprises a first and a second split that each receive refrigerant from a receiver, wherein the first and second split each include a plurality of circuits, and wherein each circuit connects to one split at a first end, passes through a tube system, and connects to an outlet at a second end.

3. The system of

claim 2, wherein the subcooler outlet is connected to an evaporator, wherein the evaporator is connected to a compressor, and wherein the compressor is connected to a condenser.

4. The system of

claim 3, further comprising an expander disposed between the subcooler and the evaporator, wherein refrigerant enters the expander at approximately 70° F. to approximately 80° F. and exits the expander at approximately 30° F. to approximately 40° F.

5. The system of

claim 4, further comprising a remote condenser connected to the compressor, wherein the remote condenser allows the condenser to be bypassed.

6. The system of

claim 2, wherein the refrigerant enters the subcooler at approximately 100° F. to approximately 120° F. and exist the subcooler at approximately 70° F. to approximately 80° F.

7. The system of

claim 2, wherein the refrigerant received from the receiver is completely liquid.

8. The system of

claim 2, wherein each split includes a plurality of circuits.

9. The system of

claim 1, further comprising a mechanism for measuring humidity, wherein the mechanism controls the splits based on a humidity value, wherein a split is activated when the humidity value falls below a predetermined level.

10. A dehumidification system that receives a humidified air flow and outputs a dehumidified air flow, comprising:

a subcooler having a plurality of splits, wherein each split includes at least one circuit;

a mechanism for activating and de-activating each split;

a system for measuring humidity of the humidified air flow; and

a system for controlling an amount of refrigerant passing through each split based on measured humidity.

11. The system of

claim 10, wherein the controlling system activates a split when the measured humidity falls below a predetermined level and de-activates a split when the humidity rises above the predetermined level.

12. The system of

claim 10, wherein moisture is removed from the humidified air flow at a rate of at least 10 pounds of water per hour when the humidified air flow has a relative humidity less than 35%, when utilizing a 60,000 BTU/HR capacity dehumidifier.

13. The system of

claim 10, further comprising:

a receiver for providing non-vaporous refrigerant to the splits;

an expander, coupled to an outlet of the subcooler, wherein the refrigerant flows from the subcooler to the expander at a temperature in a range of approximately 70° F. to approximately 80° F.;

an evaporator, coupled to an outlet of the expander, wherein the refrigerant flows from the expander to the evaporator at a temperature in a range of approximately 30° F. to approximately 40° F;

a compressor, coupled to an outlet of the evaporator, wherein the refrigerant flows from the evaporator to the compressor at a temperature in a range of approximately 45° F. to approximately 55° F.;

a condenser, coupled to an outlet of the compressor, wherein the refrigerant flows from the compressor to the condenser at a temperature in a range of approximately 140° F. to approximately 150° F.; and

wherein an outlet of the condenser is coupled to the receiver, wherein the refrigerant flows from the condenser to the receiver at a temperature in a range of approximately 100° F. to approximately 120° F.

14. An air dehumidification and drying system, comprising:

a drying booth for drying waterborne coatings; and

a dehumidification system, operatively attached to the drying booth, wherein the dehumidification system comprises a subcooler having a plurality of splits, wherein each split includes at least one circuit.

15. The system of

claim 14, further comprising a filtration system, operatively attached to the drying booth, for filtering a re-circulated air flow, wherein the air flow is directed from the drying booth, through the filtration system, through the dehumidification system, and returned to the drying booth.

16. The system of

claim 14, further comprising a system for measuring a humidity value of an air flow, wherein the splits of the subcooler are controlled based on the humidity value.

17. The system of

claim 16, wherein one or more splits are activated when the humidity value falls below a predetermined level.

18. The system of

claim 14, wherein the subcooler cools non-vaporous refrigerant by at least approximately 30° F.

19. The system of

claim 14, wherein the dehumidification system further comprises an expander connected to an outlet of the subcooler, an evaporator connected to an outlet of the expander, a compressor connected to an outlet of the evaporator, and a condenser connected to an outlet of the compressor.

20. The system of

claim 19, wherein the dehumidification system further comprises a receiver for feeding non-vaporous refrigerant to the subcooler.

21. The system of

claim 19, wherein the dehumidification system further comprises a remote condenser connected to the outlet of the compressor, and wherein the remote condenser allows the condenser to be bypassed.

22. The system of

claim 14, wherein each split includes a plurality of circuits.

23. A method of modulating the capacity of a subcooler, comprising the following steps:

providing a dehumidification system that includes a subcooler having a plurality of splits that each include at least one circuit;

directing an air flow through the dehumidification system;

measuring a humidity value of the air flow; and

controlling the splits based on the humidity value.

24. The method of

claim 23, wherein the step of providing a dehumidification systems comprises the steps of:

providing an expander operatively attached to an outlet of the subcooler;

providing an evaporator operatively attached to an outlet of the expander;

providing a compressor operatively attached to an outlet of the evaporator;

providing a condenser operatively attached to an outlet of the compressor; and

providing a receiver operatively attached to an outlet of the condenser, wherein the receiver feeds non-vaporous refrigerant to the subcooler.

25. The method of

claim 23, further comprising the steps of:

providing non-vaporous refrigerant to the subcooler; and

cooling the refrigerant by at least approximately 30F. in the subcooler.

26. The method of

claim 23, further comprising the step of providing a drying booth operatively attached to the dehumidification system.

27. The method of

claim 23, wherein the measuring step comprises the steps of:

measuring humidity of the air flow; and

transmitting the measured humidity to the splits.

28. The method of

claim 27, wherein the controlling step includes the steps of:

receiving the measured humidity;

activating at least one split when the measured humidity falls below a predetermined level; and

de-activating at least one split when the measured humidity rises above a predetermined level.

29. A method of removing moisture from air, comprising the following steps:

providing a dehumidification system including a subcooler having a plurality of splits that each include at least one circuit;

flowing non-vaporous refrigerant from a condenser to the subcooler;

modulating the capacity of the subcooler by controlling the splits;

flowing the refrigerant from the subcooler to an expander;

flowing the refrigerant from the expander to an evaporator; and

removing moisture from an air flow by directing the air flow over the evaporator.

30. The method of

claim 29, wherein the removing step comprises the step of removing moisture from the air flow at a rate of at least 5 pounds of water per hour when the air flow has a relative humidity of approximately 30%, when utilizing a 60,000 BTU/HR capacity dehumidifier.

31. The method of

claim 29, wherein the removing step comprises the step of removing moisture from the air flow at a rate of at least 16 pounds of moisture per hour when the air flow has a relative humidity of approximately 40%, when utilizing a 60,000 BTU/HR capacity dehumidifier.

32. The method of

claim 29, further comprising the steps of:

flowing the refrigerant from the evaporator to a compressor; and

flowing the refrigerant from the compressor to the condenser.

33. The method of

claim 29, wherein the modulating step comprises the steps of:

measuring a humidity value of the air flow;

transmitting the humidity value to the splits; and

controlling the splits based on the transmitted humidity value.

34. The method of

claim 33, wherein the controlling step comprises the steps of:

activating a split when the humidity value falls below a predetermined level; and

de-activating a split when the humidity value rises above the predetermined level.

35. A method for drying waterborne coatings, comprising the following steps:

providing an article coated with a waterborne coating;

directing an air flow over the coated article; and

removing moisture from the air flow by directing the air flow to a dehumidification system having a subcooler including a plurality of splits, wherein each split includes at least one circuit.

36. The method of

claim 35, further comprising the steps of:

measuring a humidity value of the air flow; and

controlling the splits of the subcooler based on the humidity value.

37. The method of

claim 36, further comprising the step of transmitting the humidity value to the subcooler, before the controlling step.

38. The method of

claim 37, wherein the controlling step comprises the steps of:

receiving the transmitted humidity value; and

activating or de-activating a splits based on the humidity value.

39. The method of

claim 35, further comprising the step of providing a drying booth, prior to providing a coated article.

40. The method of

claim 39, further comprising the step of directing the air flow into a filtration system, prior to the removing step.

41. The method of

claim 40, further comprising the step of drying the coated article by directing the air flow from the dehumidification system to the drying booth, after the removing step.