Patent Publication Number: US-10758105-B2

Title: Heating assembly for a washing appliance

Description:
FIELD OF THE INVENTION 
     The present subject matter relates generally to washing appliances, such as dishwashing appliances and, more particularly, to a heating assembly of a washing appliance. 
     BACKGROUND OF THE INVENTION 
     Dishwashing appliances generally include a tub that defines a wash chamber. Rack assemblies can be mounted within the wash chamber for receipt of articles for washing where, e.g., detergent, water, and heat, can be applied to remove 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. In addition, spray-arm assemblies within the wash chamber may be used to apply or direct fluid towards the articles disposed within the rack assemblies in order to clean such articles. 
     Fluids used in the cleaning process may be heated. For example, hot water may be supplied to the dishwasher and/or the dishwasher may include one or more heat sources for heating fluids used in wash or rinse cycle and for providing heat during a drying cycle. It is common to provide dishwashers with rod-type, resistive heating elements in order to supply heat within the wash chamber during one or more of the dishwasher cycles. Generally, these heating elements include an electric resistance-type wire that is encased in a ceramic-filled, metallic sheath. The usage of such electric heaters typically leads to increased energy consumption. Moreover, a significant portion of the energy used to heat the water, e.g., for the wash cycle, may be wasted when the hot water is discharged from the dishwasher after being applied to the articles. 
     Accordingly, an improved heating device for a dishwashing appliance that provides for improved energy usage would be welcomed in the technology. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Aspects and advantages of the technology 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 technology. 
     In one embodiment a dishwashing appliance is provided. The dishwashing appliance includes a tub defining a wash chamber, a water storage chamber, an inlet defined in the tub and providing fluid communication into the wash chamber and a heat pipe heat exchanger. The heat pipe heat exchanger includes a sealed casing, a working fluid contained within the sealed casing, a condenser section, and an evaporator section. The condenser section is in operative communication with the inlet upstream of the wash chamber. The dishwashing appliance also includes a fluid circulation system configured to deliver fluid to the wash chamber from the water storage chamber. The fluid circulation system includes a spray nozzle configured to spray wash fluid onto the evaporator section of the heat pipe heat exchanger. 
     In another embodiment, a method of operating a dishwashing appliance is provided. The method includes pumping wash fluid from a storage chamber of the dishwashing appliance to a spray nozzle and spraying the pumped wash fluid from the spray nozzle onto an evaporator section of a heat pipe heat exchanger. The method also includes flowing ambient air across a condenser section of the heat pipe heat exchanger and into a wash chamber of the dishwashing appliance from the condenser section of the heat pipe heat exchanger. 
     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. 
         FIG. 1  illustrates a front view of one embodiment of a dishwashing appliance as may incorporate one or more embodiments of the present subject matter. 
         FIG. 2  illustrates a cross-sectional side view of the dishwashing appliance shown in  FIG. 1 , particularly illustrating various internal components of the dishwashing appliance. 
         FIG. 3  provides a schematic view of a dishwashing appliance according to one or more embodiments of the present subject matter, with a fluid circulation system including a diverter valve, the diverter valve in a first position. 
         FIG. 4  provides a schematic view of the dishwashing appliance of  FIG. 3  with the diverter valve in a second position. 
         FIG. 5  provides a schematic view of a dishwashing appliance according to one or more additional embodiments of the present subject matter. 
         FIG. 6  provides a sectional perspective view of a heat pipe heat exchanger and spray nozzles according to one or more embodiments of the present subject matter. 
         FIG. 7  provides a sectional perspective view of a heat pipe heat exchanger and spray nozzles according to one or more additional embodiments of the present subject matter. 
         FIG. 8  provides a flow chart of an exemplary method of operating a dishwashing appliance according to one or more embodiments of the present subject matter. 
     
    
    
     DETAILED DESCRIPTION 
     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. 
     As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. As used herein, terms of approximation such as “generally,” “about,” or “approximately” include values within ten percent greater or less than the stated value. When used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction, e.g., “generally vertical” includes forming an angle of up to ten degrees in any direction, e.g., clockwise or counterclockwise, with the vertical direction V. 
     Referring now to the drawings,  FIGS. 1 and 2  illustrate one embodiment of a domestic dishwashing appliance  100  that may be configured in accordance with aspects of the present disclosure. As shown in  FIGS. 1 and 2 , the dishwashing appliance  100  may include a cabinet  102  having a tub  104  therein defining a wash chamber  106 . The tub  104  may generally include a front opening (not shown) and a door  108  hinged at its bottom  110  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. As shown in  FIG. 1 , a latch  123  may be used to lock and unlock the door  108  for access to the chamber  106 . 
     As is understood, the tub  104  may generally have a rectangular cross-section defined by various wall panels or walls. For example, as shown in  FIG. 2 , the tub  104  may include a top wall  160  and a bottom wall  162  spaced apart from one another along a vertical direction V of the dishwashing appliance  100 . Additionally, the tub  104  may include a plurality of sidewalls  164  (e.g., four sidewalls) extending between the top and bottom walls  160 ,  162 . It should be appreciated that the tub  104  may generally be formed from any suitable material. However, in several embodiments, the tub  104  may be formed from a ferritic material, such as stainless steel, or a polymeric material. 
     As particularly shown in  FIG. 2 , upper and lower guide rails  124 ,  126  may be mounted on opposing side walls  164  of the tub  104  and may be configured to 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 ). Additionally, each rack  130 ,  132  may be adapted for movement along a transverse direction T 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 may be facilitated by rollers  135  and  139 , for example, mounted onto racks  130  and  132 , respectively. As is generally understood, 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 . 
     Additionally, the dishwashing appliance  100  may also include a lower spray-arm assembly  144  that is configured to be rotatably mounted within a lower region  146  of the wash chamber  106  directly above the bottom wall  162  of the tub  104  so as to rotate in relatively close proximity to the rack assembly  132 . As shown in  FIG. 2 , a mid-level spray-arm assembly  148  may be located in an upper region of the wash chamber  106 , such as by being located in close proximity to the upper rack  130 . Moreover, an upper spray assembly  150  may be located above the upper rack  130 . 
     As is generally understood, the lower and mid-level spray-arm assemblies  144 ,  148  and the upper spray assembly  150  may generally form part of a fluid circulation system  152  for circulating fluid (e.g., water and dishwasher fluid which may also include water, detergent, and/or other additives, and may be referred to as wash fluid) within the tub  104 . As shown in  FIG. 2 , the fluid circulation system  152  may also include a recirculation pump  154  located in a machinery compartment  140  below the bottom wall  162  of the tub  104 , as is generally recognized in the art, and one or more fluid conduits for circulating the fluid delivered from the pump  154  to and/or throughout the wash chamber  106 . The tub  104  may include a sump  142  positioned at a bottom of the wash chamber  106  for receiving fluid from the wash chamber  106 . The recirculation pump  154  receives fluid from sump  142  to provide a flow to fluid circulation system  152 , which may include a switching valve or diverter  155  ( FIGS. 3 and 4 ) to select flow to one or more of the lower and mid-level spray-arm assemblies  144 ,  148  and the upper spray assembly  150 . 
     Moreover, each spray-arm assembly  144 ,  148  may include an arrangement of discharge ports or orifices for directing washing liquid onto dishes or other articles located in rack assemblies  130  and  132 , which may provide 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. 
     A drain pump  156  may also be provided in the machinery compartment  140  and in fluid communication with the sump  142 . The drain pump  156  may be in fluid communication with an external drain (not shown) to discharge fluid, e.g., used wash liquid, from the sump  142 . 
     The dishwashing appliance  100  may be further equipped with a controller  137  configured to regulate operation of the dishwasher  100 . The controller  137  may generally include one or more memory devices and one or more microprocessors, such as one or more general or special purpose microprocessors 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 dishwashing appliance  100 . In the illustrated embodiment, the controller  137  is located within a control panel area  121  of the door  108 , as shown in  FIG. 1 . In such an embodiment, input/output (“I/O”) signals may be routed between the control system and various operational components of the dishwashing appliance  100  along wiring harnesses that may be routed through the bottom of the door  108 . Typically, the controller  137  includes a user interface panel/controls  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. Additionally, 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 also include a display component, such as a digital or analog display device designed to provide operational feedback to a user. As is generally understood, the user interface  136  may be in communication with the controller  137  via one or more signal lines or shared communication busses. It should be noted that controllers  137  as disclosed herein are capable of and may be operable to perform any methods and associated method steps as disclosed herein. 
     It should be appreciated that the present subject matter is not limited to any particular style, model, or configuration of dishwashing appliance. The exemplary embodiment depicted in  FIGS. 1 and 2  is simply provided for illustrative purposes only. For example, different locations may be provided for the user interface  136 , different configurations may be provided for the racks  130 ,  132 , and other differences may be applied as well. 
     Turning now to  FIGS. 3 and 4 , in at least some embodiments, a heat pipe heat exchanger  202  may be provided in order to promote drying of the wash chamber  106  and/or wet articles therein. A heat pipe heat exchanger, hereinafter referred to as a “heat pipe,” is an efficient means of transferring thermal energy, e.g., heat, from one location to another. For example, in some embodiments, as illustrated in  FIG. 4 , the heat pipe  202 , as described in more detail hereinbelow, may be configured to capture heat from liquids, e.g., a spray  18  of water and/or wash fluid, sprayed onto one end of the heat pipe  202  from a water storage chamber by one or more spray nozzles  222 , and the heat pipe  202  may use the captured heat for heating an air stream on the other end. For example, in some embodiments, the heated air stream  12  may be used to dry the wash chamber  106  of dishwashing appliance  100  and wet articles, e.g., dishes, located therein. In such embodiments, the water storage chamber may be the sump  142  of the dishwashing appliance  100 . In such embodiments, the heat pipe  202  may advantageously be the only heat source for the drying cycle, e.g., the dishwasher appliance  100  may not include a resistance heating element and/or may not use a resistance heating element during the drying cycle. Further, in such embodiments, the operation of the dishwashing appliance  100  may include holding liquid in the sump  142  during at least a part of the drying cycle. That is, rather than activating the drain pump  156  ( FIG. 2 ) shortly after the wet cycle is complete and draining out the hot liquid from the sump  142 , the liquid may be retained within the appliance, e.g., within the sump  142  of dishwashing appliance  100  in order to extract thermal energy from the liquid for the drying cycle, e.g., by spraying the liquid onto the heat pipe  202 , before discharging the liquid from the sump  142 . 
     The heat pipe  202  includes a sealed casing  204  containing a working fluid  206  in the casing  204 . In some embodiments, the working fluid  206  may be water. In other embodiments, suitable working fluids for the heat pipe  202  include acetone, methanol, ethanol, or toluene. In other embodiments, any suitable fluid may be used for working fluid  206 , e.g., that is compatible with the material of the casing  204  and is suitable for the desired operating temperature range. The heat pipe  202  extends between a condenser section  208  and an evaporator section  210 . The working fluid  206  contained within the casing  204  of the heat pipe  202  absorbs thermal energy at the evaporator section  210 , whereupon the working fluid  206  travels in a gaseous state from the evaporator section  210  to the condenser section  208 . The gaseous working fluid  206  condenses to a liquid state and thereby releases thermal energy at the condenser section  208 . A plurality of fins  212  may be provided on an exterior surface of the casing  204  at one or both of the condenser section  208  and the evaporator section  210 . The fins  212  may provide an increased contact area between the heat pipe  202  and air  12  (e.g., at the condenser section  208 ) and/or spray  18  of wash fluid (e.g., at the evaporator section  210 ) flowing around the heat pipe  202  for improved transfer of thermal energy. 
     The heat pipe  202  may include an internal wick structure (not shown) to transport liquid working fluid  206  from the condenser section  208  to the evaporator section  210  by capillary flow. In some embodiments, the heat pipe  202  may be constructed and arranged such that the liquid working fluid  206  returns to the evaporator section  210  solely by gravity flow. For example, as illustrated in  FIGS. 3 through 5 , the heat pipe  202  may be arranged such that the condenser section  208  is positioned above the evaporator section  210  along the vertical direction V, whereby condensed working fluid  206  in a liquid state may flow from the condenser section  208  to the evaporator section  210  by gravity. In such embodiments, where the liquid working fluid  206  may return to the evaporator section  210  by gravity, the wick structure may be omitted. Such embodiments may advantageously provide a reduced cost and simpler heat pipe  202  by omitting the wick structure. 
     The evaporator section  210  of the heat pipe  202  may be in operative communication with the sump  142 , e.g., via the fluid circulation system  152 , including one or more spray nozzles  222  of the fluid circulation system  152 . As shown in  FIGS. 3 through 5 , the evaporator section  210  of the heat pipe  202  may be in fluid communication with the fluid circulation system  152 . For example, the fluid circulation system  152  may include one or more spray nozzles  222  configured to spray wash fluid onto the evaporator section  210  of the heat pipe  202 . The heat pipe  202  may also be in fluid communication with an ambient environment externally around the dishwashing appliance  100 , such as the ambient environment around, e.g., in close proximity to, an exterior of the dishwashing appliance  100 , such as the immediate surroundings of the dishwashing appliance  100  from which air may be drawn directly into an intake  254 . As illustrated, e.g., in  FIGS. 3 through 5 , the tub  104  may include an inlet  214  defined in the tub  104 . The inlet  214  may provide fluid communication into the wash chamber  106  of the dishwashing appliance  100 . The inlet  214  may be in direct fluid communication with the wash chamber  106 , and the condenser section  208  of the heat pipe  202  may be positioned proximate to the inlet  214 , e.g., immediately adjacent to the inlet  214 . The dishwashing appliance  100  may also include a fan  216  configured to urge hot air  12  through the inlet  214 . For example, in some embodiments, the fan  216  may be configured to urge ambient air  10  from the ambient environment through the inlet  214 , e.g., as illustrated in  FIGS. 4 and 5 . In various embodiments, the condenser section  208  of the heat pipe  202  may be in operative communication with the inlet  214  upstream of the wash chamber  106 . For example, as illustrated, the condenser section  208  may be positioned at or proximate to the inlet  214 . For example, the condenser section  208  of the heat pipe  202  may be positioned between the intake  254  and the wash chamber  106 , e.g., downstream of the intake  254  and upstream of inlet  214  into the tub  104 . 
     As shown, the ambient air  10  may be drawn into the dishwashing appliance  100  via the intake  254 , e.g., the ambient air  10  may be urged from the ambient environment through the intake  254  by the fan  216 , and from the intake  254  into the wash chamber  106  via the inlet  214 , where the air passes over and around the condenser section  208  of the heat pipe  202  while travelling between the intake  254  and the inlet  214 , including over and around fins  212  on the heat pipe  202  in some embodiments, such that the air receives thermal energy from gaseous working fluid  206  which condenses in the condenser section  208  of the heat pipe  202 , to create a flow of hot dry air  12 . 
     The flow of hot dry air  12  may travel through the wash chamber  106  to promote drying of dishes or other articles, e.g., located in rack assemblies  130  and  132  within the wash chamber  106 , whereupon the hot dry air  12  imparts thermal energy to and receives moisture from the articles and/or the wash chamber  106 . As used herein, “hot air” includes air having a temperature of at least about 90° F., such as at least about 100° F., such as between about 100° F. and about 160° F., such as between about 115° F. and about 155° F., such as about 135° F. As noted above, terms of approximation, such as “generally,” or “about” are used herein throughout to include values within ten percent greater or less than the stated value. For example, “about 135° F.” includes from 121.5° F. to 148.5° F. As used herein, “dry air” includes air having a relative humidity less than about twenty percent, such as less than about fifteen percent, such as less than about ten percent, such as less than about five percent, such as about zero. 
     Where the evaporator section  210  of the heat pipe  202  is in operative communication with the sump  142 , e.g., via spray nozzles  222 , the temperature of the hot dry air  12  will be approximately the same as the temperature of the liquid in the sump  142 , depending at least in part on the efficiency of the heat pipe  202 . For example, the temperature of the wash liquid stored in the sump  142  may be about 150° F. to about 160° F. In such embodiments, depending on the dimensions of the heat pipe  202 , e.g., the length and diameter of the heat pipe  202 , and the type of working fluid  206 , the hot air  12  may be anywhere within the temperature ranges set forth above, but will generally be less than the temperature of the liquid in the water storage chamber, e.g., sump  142 . 
     One of skill in the art will recognize that the heat pipe  202  may be activated when one or both of the spray nozzles  222  and the fan  216  operates. For example, liquid working fluid  206  may be stored in the evaporator section  210  until the spray nozzles  222  operate to provide the spray  18  ( FIGS. 4 and 5 ) to the evaporator section  210 , whereupon thermal energy from the spray  18  may be transferred to the working fluid  206 , causing the working fluid  206  to evaporate and travel to the condenser section  208 . Further, when the fan  216  operates, e.g., when the fan  216  urges ambient air  10  about the condenser section  208 , thermal energy may then be transferred from the evaporated working fluid  206  at the condenser section  208  to the air  10 . As the working fluid  206  in the condenser section  208  becomes relatively cool, the working fluid  206  will condense and flow in liquid form to the evaporator section  210 , e.g., by gravity and/or capillary flow. 
     As shown in  FIGS. 3 and 4 , in some embodiments, the fluid circulation system  152  may further include a diverter valve  155  downstream of the recirculation pump  154 . As will be understood, the recirculation pump  154  may be downstream of the water storage chamber, e.g., sump  142 , in that that the pump  154  receives wash fluid  14  from the sump  142 , e.g., the recirculation pump  154  may be connected to the sump  142  at an intake of the recirculation pump  154  such that, when activated, the recirculation pump  154  pumps liquid  14  from the sump  142 . Similarly, the diverter valve  155  may be downstream of the recirculation pump  142  in that the diverter valve  155  may be connected to an outlet of the recirculation pump  154  to receive a flow of liquid  16  from the recirculation pump  154 , either directly or via one or more conduits, etc. In such embodiments, the diverter valve  155  may be selectively positionable in a plurality of positions to direct liquid  17  to one or more additional components of the fluid circulation system  152 , such as one or more of the spray arms  144 ,  148 , etc., or the spray nozzles  222 . For example, the plurality of positions of the diverter valve  155  may include at least a first position and a second position. When the diverter valve  155  is in the first position, liquid  17  may be delivered to at least one spray assembly positioned within the wash chamber  106 , e.g., at least one of the lower and mid-level spray-arm assemblies  144 ,  148  and the upper spray assembly  150 . When the diverter valve  155  is in the second position, liquid  17  may be delivered to the spray nozzles  222  in fluid communication with the evaporator section  210  of the heat pipe  202 . As shown in  FIGS. 3 and 4 , the liquid  14  from the sump  142  may be delivered from the recirculation pump  154  as a pressurized flow  16  to the diverter valve  155 . As shown in  FIG. 3 , when the diverter valve  155  is in the first position, the diverter valve  155  may provide liquid  17  to one or more spray arms  144  and/or  148  such that the spray  18  of wash fluid emanates from one or both spray arms  144  and/or  148 . As shown in  FIG. 4 , when the diverter valve  155  is in the second position, the diverter valve  155  may direct the liquid  17  to the spray nozzles  222 , such that the spray  18  emanates from the spray nozzles  222  and onto the evaporator section  210  of the heat pipe  202 . 
     Also shown in  FIGS. 3 and 4 , the recirculation pump  154  may include an inline heating element  153  (sometimes also referred to as an “inline heater”) in operative communication with the pump  154 , e.g., the inline heating element  153  may be provided as a resistance heating element such as a heating rod which is integrated with and at least partially encircles the pump  154 . The inline heating element  153  may be activated to heat wash fluid flowing through the recirculation pump  154 , e.g., during the wet cycle, as shown in  FIG. 3 . In some embodiments, the wash fluid may be heated again by the inline heating element  153  during the dry cycle, e.g., when the wash fluid is flowed from the sump  142  to the spray nozzles  222 , as shown in  FIG. 4 . In other embodiments, the residual heat remaining in the wash fluid after the wash fluid returns to the sump  142  from the wash chamber  106  in the wet cycle may be sufficient to activate the heat pipe  202 , consequently, some embodiments may not include activating the inline heating element  153  during the dry cycle. 
     As shown in  FIG. 5 , in some embodiments, the fluid circulation system  152  may include an additional pump  157  which is dedicated to the heat pipe  202 . In such embodiments, the dedicated pump  157  may be configured to pump wash fluid directly from the dedicated pump  157  to the one or more spray nozzles  222 , e.g., without an intervening structure such as the diverter valve  155 . In some embodiments, the dedicated pump  157  may also include an inline heating element  159 , similar to the inline heating element  153  described above. 
     As shown in  FIGS. 3 through 5 , the heat pipe  202  may be disposed in a side chamber  218  of the tub  104 . The side chamber  218  may be in fluid communication with the sump  142  by gravity. For example, as shown in  FIGS. 4 and 5 , the spray  18  may collect on and drip off of the evaporator section  210 , forming a stream of runoff  20 , and the side chamber  218  may be positioned above the sump  142  along the vertical direction V, such that the runoff  20  from the side chamber  218  flows by gravity to the sump  142 . As shown in  FIGS. 3 and 4 , in some embodiments, the dishwashing appliance  100  may include a return conduit  219  extending from the side chamber  218  to the sump  142  and external to the tub  104 . In such embodiments, the runoff  20  may flow from the side chamber  218  by gravity via the return conduit  219  to the sump  142 . As shown in  FIG. 5 , in some embodiments, the side chamber  218  may include an outlet  220  at or near a bottom of the side chamber  218 , and the outlet  220  may be in fluid communication with the wash chamber  106 . In such embodiments, the runoff  20  may flow from the side chamber  218  by gravity via the outlet  220  through the wash chamber  106  and back to the sump  142 . 
     Sectional perspective views of a portion of the side chamber  218  according to various embodiments of the present disclosure are illustrated in  FIGS. 6 and 7 . As shown in  FIGS. 6 and 7 , the spray nozzles  222  may include at least one spray nozzle  222  positioned on each of two opposing sides of the heat pipe  202 . For example, the one or more spray nozzles  222  may include a first spray nozzle  222  on a first side of the heat pipe  202  and a second spray nozzle  222  on a second side of the heat pipe, where the second side is opposite of the first side. In such embodiments, the first and second spray nozzles  222  may direct the spray  18  (e.g.,  FIGS. 4 and 5 ) towards one another. 
     In some embodiments, the heat pipe  202  may be generally flat, e.g., rectangular, as illustrated in  FIGS. 6 and 7 , with the longer sides of the rectangular heat pipe  202  oriented towards the spray nozzles  222  to provide a larger surface area to receive the spray  18 , e.g., as compared to the smaller sides of the rectangular heat pipe  202 , to maximize the proportion of the heat pipe  202  exposed to the spray  18 . Although only a single heat pipe  202  is shown, in some embodiments, multiple heat pipes  202  may be provided, e.g., in a staggered manner such that each heat pipe  202  receives at least a portion of the spray  18  from the spray nozzles  222 . 
     Still referring to  FIGS. 6 and 7 , the spray nozzles  222  may be provided as apertures  222  formed in one or more pressure conduits  224 , where the pressure conduits  224  receive the pressurized flow  16  from the recirculation pump  154  ( FIG. 4 ) or the dedicated pump  157  ( FIG. 5 ). The pressure conduits  224  may be positioned on or outside of the side chamber  218 . For example, the pressure conduits  224  may be integrally formed with the side chamber  218 , as shown in  FIGS. 6 and 7 . The spray nozzles  222  may be oriented to direct the spray  18  downward along the vertical direction V, e.g., as illustrated in  FIG. 6 , or upward along the vertical direction V, e.g., as illustrated in  FIG. 7 . In further embodiments, the spray nozzles  222  may be oriented to direct the spray  18  generally perpendicular to the vertical direction V, e.g., as illustrated in  FIGS. 4 and 5 . 
     Turning now to  FIG. 8 , embodiments of the present subject matter also include methods of operating a dishwashing appliance, such as the example method  1000  illustrated in  FIG. 8 . As noted above, such methods may at least in part be embodied as instructions stored in memory and executed by the controller  137 . The method  1000  may include a step  1010  of pumping wash fluid, e.g., wash fluid  17 , from a storage chamber, e.g., sump  142 , of the dishwashing appliance to a spray nozzle, e.g., one of the one or more spray nozzles  222 . The method  1000  may further include a step  1020  of spraying the pumped wash fluid from the spray nozzle onto an evaporator section of a heat pipe heat exchanger, e.g., the evaporator section  210  of one or more of the exemplary heat pipes  202  shown in  FIGS. 3 through 7  and described above. The method  1000  may also include a step  1030  of flowing ambient air  10  across a condenser section of the heat pipe heat exchanger to form a flow of hot, dry air  12  into a wash chamber of the dishwashing appliance from the condenser section of the heat pipe heat exchanger. 
     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.