US20160192821A1

US20160192821A1 - Dishwasher appliance having energy recovery features

Info

Publication number: US20160192821A1
Application number: US14/591,344
Authority: US
Inventors: Shree Kumar; Ronald Scott Tarr
Original assignee: Haier US Appliance Solutions Inc
Current assignee: Haier US Appliance Solutions Inc
Priority date: 2015-01-07
Filing date: 2015-01-07
Publication date: 2016-07-07

Abstract

Dishwasher appliances are provided. A dishwasher appliance includes a cabinet defining an interior, and a tub disposed within the interior and defining a wash chamber for the receipt of articles for cleaning The dishwasher appliance further includes a sump and a fluid circulation conduit. The dishwasher appliance further includes a closed-loop adsorption assembly in fluid communication with the wash chamber. The closed-loop adsorption assembly includes an inlet defined in the tub, an outlet defined in the tub, and a desiccant assembly in fluid communication with the inlet and the outlet. The desiccant assembly includes an inner passage for receiving fluid from the wash chamber, an intermediate passage surrounding the inner passage, an outer passage surrounding the intermediate passage, and a desiccant module disposed in the intermediate passage. Fluid received in the inner passage is flowable through the intermediate passage to the outer passage.

Description

FIELD OF THE INVENTION

The present disclosure relates generally to dishwasher appliances, and more particularly to dishwasher appliances which utilize desiccants to recover energy during operation.

BACKGROUND OF THE INVENTION

Modern dishwashers typically include a wash chamber where e.g., detergent, water, and heat can be applied to clean food or other materials from dishes and other articles being washed. Various cycles may be included as part of the overall cleaning process. For example, a typical, user-selected cleaning option may include a wash cycle and rinse cycle (referred to collectively as a wet cycle), as well as a drying cycle. A pre-wash cycle may also be included as part of the wet cycle, and may be automatic or an option for particularly soiled dishes.
Presently, many known dishwasher appliances utilize venting arrangements to vent moist air during the drying cycle, in order to facilitate drying. New air is drawn into the dishwasher appliance as the moist air is vented from the dishwasher appliance to the exterior environment. Such approach, however, can be problematic. For example, venting the moist air during the drying cycle can add moisture and heat to the surrounding environment, such as the kitchen or other room where the dishwasher appliance is located. Additionally, the air drawn into the dishwasher appliance from the surrounding environment can, in some cases, potentially be dirty or include undesirable particles, etc.
More recently, attempts have been made to recirculate air within the dishwasher appliances in order to reduce or avoid the above discussed disadvantages, and to generally recover the associated energy. For example, adsorbent assemblies have been utilized in dishwasher appliances in attempts to remove moisture during operation. However, known adsorbent assemblies utilized in such manner have generally proved to be relatively inefficient.
Accordingly, improved dishwasher appliances are desired in the art. In particular, dishwasher appliances which provide improved air recirculation and energy recovery during operation would be advantageous.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In accordance with one embodiment of the present disclosure, a dishwasher appliance is provided. The dishwasher appliance includes a cabinet defining an interior, and a tub disposed within the interior and defining a wash chamber for the receipt of articles for cleaning The dishwasher appliance further includes a sump for collecting liquid from the chamber, and a fluid circulation conduit for circulating liquid in the tub. The dishwasher appliance further includes a closed-loop adsorption assembly in fluid communication with the wash chamber. The closed-loop adsorption assembly includes an inlet defined in the tub, an outlet defined in the tub, and a desiccant assembly in fluid communication with the inlet and the outlet. The desiccant assembly includes an inner passage for receiving fluid from the wash chamber, an intermediate passage surrounding the inner passage, an outer passage surrounding the intermediate passage, and a desiccant module disposed in the intermediate passage. Fluid received in the inner passage is flowable through the intermediate passage to the outer passage.
In accordance with another embodiment of the present disclosure, a dishwasher appliance is provided. The dishwasher appliance includes a cabinet defining an interior, and a tub disposed within the interior and defining a wash chamber for the receipt of articles for cleaning The dishwasher appliance further includes a sump for collecting liquid from the chamber, and a fluid circulation conduit for circulating liquid in the tub. The dishwasher appliance further includes a closed-loop adsorption assembly in fluid communication with the wash chamber. The closed-loop adsorption assembly includes an inlet defined in the tub, an outlet defined in the tub, and a desiccant assembly in fluid communication with the inlet and the outlet. The desiccant assembly includes an inner passage for receiving fluid from the wash chamber, an intermediate passage surrounding the inner passage, an outer passage surrounding the intermediate passage, a desiccant module disposed in the intermediate passage, and a heating unit disposed in the inner passage. Fluid received in the inner passage is flowable through the intermediate passage to the outer passage. The inner passage, the intermediate passage, and the outer passage each have a generally rectangular cross-sectional profile. A maximum thickness of the intermediate passage is between approximately 15 millimeters and approximately 50 millimeters, and a maximum length of the intermediate passage is between approximately 200 millimeters and approximately 400 millimeters.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 provides a front, perspective view of a dishwasher appliance in accordance with one embodiment of the present disclosure;

FIG. 2 provides a side, cross-sectional view of a dishwasher appliance in accordance with one embodiment of the present disclosure;

FIG. 3 provides a schematic view of various components of a dishwasher appliance, including a closed-loop adsorption assembly, in accordance with one embodiment of the present disclosure;

FIG. 4 provides a side cross-sectional view of components of a closed-loop adsorption assembly in accordance with one embodiment of the present disclosure;

FIG. 5 provides a side cross-sectional view of components of a closed-loop adsorption assembly in accordance with another embodiment of the present disclosure;

FIG. 6 provides a cross-sectional profile view of a desiccant assembly of a closed-loop adsorption assembly in accordance with one embodiment of the present disclosure; and

FIG. 7 provides a cross-sectional profile view of a desiccant assembly of a closed-loop adsorption assembly in accordance with another embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
FIGS. 1 and 2 depict an exemplary domestic dishwasher appliance 100 that may be configured in accordance with aspects of the present disclosure. For the particular embodiment of FIG. 1, the dishwasher appliance 100 includes a cabinet 102 that defines an interior 103. A tub 104 is disposed in the interior 103. Tub 104 defines a wash chamber 106. Chamber 106 is configured for the receipt of articles for cleaning, such as dishes, cups, utensils, etc. The tub 104 includes a front opening (not shown) and a door 120 hinged at or near its bottom side wall 122 for movement between a normally closed vertical position (shown in FIGS. 1 and 2), wherein the wash chamber 106 is sealed shut for washing operation, and a horizontal open position for loading and unloading of articles from the dishwasher appliance 100. Latch 123 is used to lock and unlock door 120 for access to chamber 106.
Upper and lower guide rails 124, 126 are mounted on tub side walls 128 and accommodate roller-equipped rack assemblies 130 and 132. Each of the rack assemblies 130, 132 may be fabricated into lattice structures including a plurality of elongated members 134 (for clarity of illustration, not all elongated members making up assemblies 130 and 132 are shown in FIG. 2). Each rack 130, 132 is adapted for movement between an extended loading position (not shown) in which the rack is substantially positioned outside the wash chamber 106, and a retracted position (shown in FIGS. 1 and 2) in which the rack is located inside the wash chamber 106. This is facilitated by rollers 135 and 139, for example, mounted onto racks 130 and 132, respectively. A silverware basket (not shown) may be removably attached to rack assembly 132 for placement of silverware, utensils, and the like, that are otherwise too small to be accommodated by the racks 130, 132.
The dishwasher appliance 100 further includes a lower spray-arm assembly 144 that is rotatably mounted within a lower region 146 of the wash chamber 106 and above a tub sump portion 142 so as to rotate in relatively close proximity to rack assembly 132. A mid-level spray-arm assembly 148 is located in an upper region of the wash chamber 106 and may be located in close proximity to upper rack 130. Additionally, an upper spray assembly 150 may be located above the upper rack 130.
The lower and mid-level spray- arm assemblies 144, 148 and the upper spray assembly 150 are fed by a fluid circulation conduit 152 for circulating water and dishwasher fluid (generally referred to as liquid) in the tub 104. A first pump 154, which may for example be located in a machinery compartment 140 located below the bottom sump portion 142 of the tub 104, may flow liquid to and through the fluid circulation conduit 152. Each spray- arm assembly 144, 148 includes an arrangement of discharge ports or orifices for directing washing liquid onto dishes or other articles located in rack assemblies 130 and 132. The arrangement of the discharge ports in spray- arm assemblies 144, 148 provides a rotational force by virtue of washing fluid flowing through the discharge ports. The resultant rotation of the lower spray-arm assembly 144 provides coverage of dishes and other dishwasher contents with a washing spray.
The dishwasher 100 is further equipped with a controller 137 to regulate operation of the dishwasher 100. The controller may include a memory and microprocessor, such as a general or special purpose microprocessor operable to execute programming instructions or micro-control code associated with a cleaning cycle. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor.
The controller 137 may be positioned in a variety of locations throughout dishwasher 100. In the illustrated embodiment, the controller 137 may be located within a control panel area 121 of door 120 as shown. In such an embodiment, input/output (“I/O”) signals may be routed between the control system and various operational components of dishwasher 100 along wiring harnesses that may be routed through the bottom side wall 122 of door 120. Typically, the controller 137 includes a user interface panel 136 through which a user may select various operational features and modes and monitor progress of the dishwasher 100. In one embodiment, the user interface 136 may represent a general purpose I/O (“GPIO”) device or functional block. In one embodiment, the user interface 136 may include input components, such as one or more of a variety of electrical, mechanical or electro-mechanical input devices including rotary dials, push buttons, and touch pads. The user interface 136 may include a display component, such as a digital or analog display device designed to provide operational feedback to a user. The user interface 136 may be in communication with the controller 137 via one or more signal lines or shared communication busses.
In general, dishwasher appliance 100 may utilize a variety of cycles to wash and, optionally, dry articles within chamber 106. For example, a wet cycle is utilized to wash articles. The wet cycle may include a main wash cycle and a rinse cycle, as well as an optional pre-wash cycle. During each such cycle, water or another suitable liquid may be utilized in chamber 106 to interact with and clean articles therein. Such liquid may, for example, be directed into chamber 106 from lower and mid-level spray- arm assemblies 144, 148 and the upper spray assembly 150. The liquid may additionally mix with, for example, detergent or other various additives which are released into the chamber during various sub-cycles of the wet cycle. A drying cycle may be utilized to dry articles after washing. During a drying cycle, for example, a heating element (not shown) may heat the chamber 106 to facilitate drying of the articles and evaporation of liquid into gas within the chamber 106. In generally, no liquid is sprayed or otherwise produced during the drying cycle.
It should be appreciated that the invention is not limited to any particular style, model, or other configuration of dishwasher, and that the embodiment depicted in FIGS. 1 and 2 is for illustrative purposes only. For example, instead of the racks 130, 132 depicted in FIG. 1, the dishwasher 100 may be of a known configuration that utilizes drawers that pull out from the cabinet and are accessible from the top for loading and unloading of articles. Other configurations may be used as well.
Referring now to FIGS. 3 through 7, dishwasher appliances 100 according to the present disclosure may further include various components which facilitate improved air recirculation and energy recovery during operation of the appliance 100. In particular, dishwasher appliances 100 may utilize desiccants to adsorb moisture, in particular during the drying cycle, and desorb such moisture during the wet cycle. Such adsorption and desorption may reduce or eliminate the need to vent air from the dishwasher appliance 100 during operation. Further, desorption may facilitate fluid heating within the dishwasher appliance 100, thus providing improved efficiency by causing the dishwasher appliance 100 to require less heating.
As illustrated, a dishwasher appliance 100 in accordance with the present disclosure may include a closed-loop adsorption assembly 200. The closed-loop adsorption assembly 200 is in fluid communication with the wash chamber 106, such that fluid is flowable to the adsorption assembly 200 from the wash chamber 106 and to the wash chamber 106 from the adsorption assembly 200. Adsorption assembly 200 thus includes an inlet 202 defined in the tub 104 and an outlet 204 defined in the tub 104. As discussed herein, adorption and desorption of moisture may advantageously occur within adsorption assembly 200.
In particular, adsorption assembly 200 may further include a desiccant assembly 210 in which adsorption and desorption of moisture may occur. Desiccant assembly 210 may be in fluid communication with the inlet 202 and the outlet 204. For example, in some embodiments, desiccant assembly 210 may be directly connected to the inlet 202 and/or outlet 204. In other embodiments, conduits may extend between the inlet 202 and/or outlet 204 and the desiccant assembly 210. As shown, assembly 200 may further include an inlet conduit 212 extending between the inlet 202 and the desiccant assembly 210 for flowing fluid from the wash chamber 106 to the desiccant assembly 210 (such as to an inner passage thereof as discussed herein). As further shown, assembly 200 may further include an outlet conduit 214 extending between the desiccant assembly 210 and the outlet 204 for flowing fluid from the desiccant assembly 210 (such as an outer passage thereof as discussed herein) to the wash chamber 106.
In exemplary embodiments as shown, the desiccant assembly 210, as well as inlet and outlet conduits 212, 214, may be disposed in the interior 103 (but exterior to the tube 104).
Desiccant assembly 210 generally includes various passages through which fluid may flow. As shown, desiccant assembly 200 may include an inner passage 222, an intermediate passage 224, and an outer passage 226. The inner passage 222 may receive fluid from the wash chamber 106. Accordingly, inner passage 222 may be directly connected to the inlet 202 or to the inlet conduit 212, such that fluid flows from the inlet 202 and/or inlet conduit 212 into the inner passage 222. Intermediate passage 224 may surround the inner passage 222, and outer passage 226 may surround the intermediate passage 226. Fluid received in the inner passage 224 may be flowable through the intermediate passage 224 to the outer passage 226. Further, wash chamber 106 may receive fluid from the outer passage 226. Accordingly, outer passage 226 may be directly connected to the outer 204 or to the outlet conduit 214, such that fluid flow from the outer passage 226 through the outlet conduit 214 and/or outlet 204.
In exemplary embodiments, desiccant assembly 210 may include various conduits which define the various passages thereof. For example, desiccant assembly 210 may further include an inner conduit 232 which defines the inner passage 222, an intermediate conduit 234 which surrounds the inner conduit 222 and defines the intermediate passage 224, and an outer conduit 236 which surrounds the intermediate conduit 234 and defines the outer passage 236. In exemplary embodiments as shown, the inner conduit 232 and the intermediate conduit 234 are perforated, and thus define perforations 233, 235 respectively therethrough, through which fluid can flow.
It should be noted that in some embodiments the inner conduit 232 can be an integral extension of the inlet conduit 212 and/or the outer conduit 236 can be an integral extension of the outlet conduit 214. In some alternative embodiments, the inner conduit 232 can be a separate component that is coupled to the inlet conduit 212 and/or the outer conduit 236 can be a separate component that is coupled to the outlet conduit 214.
As shown, as desiccant module 240 is disposed in the intermediate passage 224, such that the desiccant module 240 generally surrounds the inner passage 222. Thus, fluid flowing from the inner passage 222 through the intermediate passage 224 to the outer passage 226 flows through the desiccant module 240 while flowing through the intermediate passage 224. This facilitates adsorption and desorption of moisture by the desiccant module 240.
In exemplary embodiments, the desiccant module 240 may include a granular desiccant 242, as shown. In exemplary embodiments, the granular desiccant 242 may be zeolite. Alternatively, however, the desiccant may be activated charcoal, calcium sulfate, calcium chloride, or another suitable molecular sieve, or any other suitable material, etc. In alternative embodiments, the desiccant module 240 may include a plurality of desiccant-coated plates (not shown). In exemplary embodiments, the desiccant coating the plates may be zeolite. Alternatively, however, the desiccant may be activated charcoal, calcium sulfate, calcium chloride, or another suitable molecular sieve, or any other suitable material, etc. The plates themselves may be formed from any suitable material, such as a suitable metal, polymer, ceramic, etc.
Adsorption assembly 200 may further include various components to facilitate adsorption and desorption as required. For example, adsorption assembly 200 may include a fan 250. The fan 250 may encourage fluid flow through the desiccant assembly 210 and adsorption assembly 200 generally. In some embodiments as shown in FIG. 4, fan 250 is disposed downstream of the desiccant assembly 210 (relative to the flow direction of fluid through the adsorption assembly 200), such as within the outlet conduit 214. In other embodiments as shown in FIG. 5, fan 250 is disposed upstream of the desiccant assembly 210 (relative to the flow direction of fluid through the adsorption assembly 200), such as within the inlet conduit 212. In still other embodiments, fan 250 may be disposed within the desiccant assembly 210, such as in inner passage 222.
Adsorption assembly 200 may further include a heating unit 255, which may be included in the desiccant assembly 210. The heating unit 255 may include one or more heating elements 257, such as two (as shown in FIG. 6), three, four (as shown in FIG. 7) or more. In some embodiments, two or four heating elements 257 may be desirable due to the rectangular cross-sectional profile of the various passages 222, 224, 226, as discussed herein. In exemplary embodiments, the heating unit 255, such as the heating elements 257 thereof, may be disposed within the inner passage 222. These embodiments are particularly advantageous because a substantial portion of the heat emitted by the heating unit 255 is trapped by the desiccant module 240. Accordingly, these embodiments are particularly energy efficient. In alternative embodiments, however, the heating unit 255, such as the heating elements 257 thereof, may for example be disposed within the outer passage 226.
Each heating element 257 may extend through the desiccant assembly 210 between the inlet of the desiccant assembly 210 (on the upstream side thereof) and the outlet of the desiccant assembly 210 (on the downstream side thereof). In some embodiments, the heating elements 257 may have constant wattages therethrough between the inlet side and the outlet side thereof. Alternatively, however, the heating elements 257 may have variable wattages therethrough between the inlet side and the outlet side thereof. For example, the wattage of a heating element 257 may be greater at the inlet side and may decrease from the inlet side to the outlet side, to reduce or prevent temperature gradients in the desiccant module 240 along the length thereof between the inlet side and the outlet side.
Referring now to FIGS. 6 and 7, the passages 222, 224, 226 of the desiccant assembly 210 may in exemplary embodiments each have a generally rectangular cross-sectional profile. In further exemplary embodiments, the rectangle may be a square. Square cross-sectional profiles are illustrated in FIG. 7, while other rectangular cross-sectional profiles are illustrated in FIG. 6. Such cross-sectional profiles may advantageously facilitate efficient fluid flow through the passages 222, 224, 226, in particular relative to oval or circular cross-sectional profiles. For example, oval or circular cross-sectional profiles may encourage generally helical flow patterns for fluid through the passages 222, 224, 226, while rectangular cross-sectional profiles encourage the patterns to be relatively less helical and more axial. Accordingly the fluid flow using such rectangular cross-sectional profiles can be relatively more efficient. It should be understood, however, that the present disclosure is not limited to rectangular cross-sectional profiles. Rather, any suitable profiles, including oval or circular cross-sectional profiles, are within the scope and spirit of the present disclosure.
Referring again to FIGS. 4 and 5, the intermediate passage 224 (which houses the desiccant assembly 240) has a thickness 260 as illustrated. In exemplary embodiments, the thickness 260 is relatively small, thus encouraging efficient fluid flow therethrough and reducing restrictions caused by the desiccant assembly 240. For example, in some embodiments, a maximum thickness 260 of the intermediate passage 224 is between approximately 15 millimeters and approximately 50 millimeters, such as between approximately 20 millimeters and approximately 40 millimeters.
Intermediate passage 224 may further have a length 262. The length 262 may in exemplary embodiments be sized relative to the thickness 260 to ensure adequate adsorption and desorption capabilities for the desiccant assembly 240 disposed in the intermediate passage 224. For example, in some embodiments, a maximum length 262 of the intermediate passage 224 is between approximately 200 millimeters and approximately 400 millimeters, such as between approximately 250 millimeters and approximately 350 millimeters.
Controller 137 may be in operable communication with the various components of the dishwasher appliance 100, such as the fan 250 and heating unit 255, and may be operable to adjust the dishwasher appliance 100 (and thus the various components) to various settings based on desired operation of the dishwasher appliance and desired adsorption or regeneration/desorption of the desiccant. For example, the controller 137 may be operable to adjust the dishwasher appliance 100 to a desorption setting wherein the heating unit 255 and optionally the fan 250 are both on. Such setting may for example be an initial setting of the dishwasher appliance 100 when a wet cycle is initiated, during an initial wash and fill within the chamber 100, or another setting at an intermediate time during a wet cycle. In this setting, operation of the heating unit 255 heats the desiccant module 240. The relatively higher temperatures within the desiccant assembly 210 facilitate regeneration and desorption of the desiccant. The released heated moisture/humidity may flow from desiccant assembly 210 through outlet 204 into the wash chamber 106, where it may mix with and heat fluid in the wash chamber 106.
The controller 137 may further be operable to adjust the dishwasher appliance 100 to an adsorption setting wherein the heating unit 255 is off but the fan 250 may be on. Such setting may for example be the setting during the drying cycle of the dishwasher appliance 100. In this setting, relatively moist/humid fluid from the wash chamber 106 may flow into the desiccant assembly 210 through inlet 202, and this moisture/humidity may be adsorbed by the desiccant, which may be at relatively lower temperatures due to inactivity of the heating unit 255.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

What is claimed is:

1. A dishwasher appliance, comprising:

a cabinet defining an interior;

a tub disposed within the interior and defining a wash chamber for the receipt of articles for cleaning;

a sump for collecting liquid from the chamber;

a fluid circulation conduit for circulating liquid in the tub; and

a closed-loop adsorption assembly in fluid communication with the wash chamber, the closed-loop adsorption assembly comprising:

an inlet defined in the tub;

an outlet defined in the tub; and

a desiccant assembly in fluid communication with the inlet and the outlet, the desiccant assembly comprising an inner passage for receiving fluid from the wash chamber, an intermediate passage surrounding the inner passage, an outer passage surrounding the intermediate passage, and a desiccant module disposed in the intermediate passage,

wherein fluid received in the inner passage is flowable through the intermediate passage to the outer passage.

2. The dishwasher appliance of claim 1, wherein the desiccant assembly further comprises a heating unit.

3. The dishwasher appliance of claim 2, wherein the heating unit is disposed within the inner passage.

4. The dishwasher appliance of claim 1, wherein the closed-loop adsorption assembly further comprises a fan.

5. The dishwasher appliance of claim 4, wherein the fan is disposed upstream of the desiccant assembly.

6. The dishwasher appliance of claim 4, wherein the fan is disposed downstream of the desiccant assembly.

7. The dishwasher appliance of claim 1, wherein the desiccant module comprises a granular desiccant.

8. The dishwasher appliance of claim 7, wherein the desiccant is zeolite.

9. The dishwasher appliance of claim 1, wherein the closed-loop adsorption assembly further comprises:

an inlet conduit extending between the inlet and the desiccant assembly for flowing fluid from the wash chamber to the inner passage; and

an outlet conduit extending between the desiccant assembly and the outlet for flowing fluid from the outer passage to the wash chamber.

10. The dishwasher appliance of claim 1, wherein the desiccant assembly further comprises an inner conduit defining the inner passage, an intermediate conduit defining the intermediate passage, and an outer conduit defining the outer passage, and wherein the inner conduit and the intermediate conduit are perforated.

11. The dishwasher appliance of claim 1, wherein the inner passage, the intermediate passage, and the outer passage each have a generally rectangular cross-sectional profile.

12. The dishwasher appliance of claim 11, wherein the inner passage, the intermediate passage, and the outer passage each have a generally square cross-sectional profile.

13. The dishwasher appliance of claim 1, wherein a maximum thickness of the intermediate passage is between approximately 15 millimeters and approximately 50 millimeters.

14. The dishwasher appliance of claim 1, wherein a maximum length of the intermediate passage is between approximately 200 millimeters and approximately 400 millimeters.

15. A dishwasher appliance, comprising:

a cabinet defining an interior;

a sump for collecting liquid from the chamber;

a fluid circulation conduit for circulating liquid in the tub;

an inlet defined in the tub;

an outlet defined in the tub;

a desiccant assembly in fluid communication with the inlet and the outlet, the desiccant assembly comprising an inner passage for receiving fluid from the wash chamber, an intermediate passage surrounding the inner passage, an outer passage surrounding the intermediate passage, a desiccant module disposed in the intermediate passage, and a heating unit disposed in the inner passage, wherein fluid received in the inner passage is flowable through the intermediate passage to the outer passage

wherein the inner passage, the intermediate passage, and the outer passage each have a generally rectangular cross-sectional profile, a maximum thickness of the intermediate passage is between approximately 15 millimeters and approximately 50 millimeters, and a maximum length of the intermediate passage is between approximately 200 millimeters and approximately 400 millimeters.

16. The dishwasher appliance of claim 15, wherein the closed-loop adsorption assembly further comprises a fan.

17. The dishwasher appliance of claim 15, wherein the desiccant module comprises a granular desiccant.

18. The dishwasher appliance of claim 17, wherein the desiccant is zeolite.

19. The dishwasher appliance of claim 15, wherein the desiccant assembly further comprises an inner conduit defining the inner passage, an intermediate conduit defining the intermediate passage, and an outer conduit defining the outer passage, and wherein the inner conduit and the intermediate conduit are perforated.

20. The dishwasher appliance of claim 15, wherein the inner passage, the intermediate passage, and the outer passage each have a generally square cross-sectional profile.