Patent Publication Number: US-9834882-B2

Title: Device and method for heat pump based clothes dryer

Description:
BACKGROUND OF THE DISCLOSURE 
     The present disclosure relates to a heat pump clothes dryer device and method wherein a circulating fluid exchanges heat with an evaporator. A cool circulating fluid is introduced to a warm humid airflow to condense and collect moisture therein to be returned to the evaporator thereby using the enthalpy of the circulating fluid, evaporator, and dryer airflow. 
     Conventional clothes dryers generally comprise an open loop air flow passage that introduces hot dry ambient air to a moist load and exhausts the resulting hot humid air to the atmosphere. These dryers have an electric heater to heat the dry ambient air to desired temperatures during a drying process. Additionally, it is known to introduce a continuous flow of cold water to the warm humid air to cause dehumidification of the air prior to being vented to the atmosphere. These dryers often have a very limited drying capacity and also have longer drying cycle times. These dryers also consume large amounts of energy and water during the drying process. 
     Solutions have been developed to reduce consumption of excess energy and water. One known solution is to circulate the moisture laden air within a closed loop system having a condenser or other heat exchanger. This condenser dryer system uses the condenser to cool the warm humid air and condense water vapor from the warm humid air into either a drain pipe or a collection tank. This air is then reheated at a heat supply and reintroduced to the load again. The heat exchanger typically uses an external ambient air as its coolant. The heat produced by the heat exchanger in this dryer will be transferred to the immediate enclosed surroundings instead of being ducted to an external atmosphere thereby increasing the room temperature. In some designs, cold water is used in the heat exchanger, eliminating this heating, but also requiring increased water usage. 
     In terms of energy use, condenser dryers typically require less system-wide energy use than conventional dryers. Energy savings result from the associated HVAC system not having to heat or cool additional air to replace that exhausted by the conventional dryer. Typically, this savings is sufficient to offset the increase in power draw, longer drying times, and ambient cooling requirements associated with condensation dryers. 
     Because the heat exchange process simply cools the internal air using ambient air or cold water, it will not dry the air in the internal loop to as low a level of humidity as the fresh, ambient air. As a consequence of the increased humidity of the air used to dry the load, this type of dryer requires relatively more time than the conventional dryer. Condenser dryers are a particularly attractive option where long, intricate ducting would be required to vent a conventional dryer. 
     Whereas condensation dryers use a passive heat exchanger cooled by ambient air, heat pump dryers use an internal heat pump having an additional refrigeration cycle. Generally known heat pump dryers help to further reduce energy consumption from the previously mentioned dryer systems. Here, warm humid air from a moist load is passed through a heat pump where the evaporator coil cools the air and condenses the water vapor into either a drain pipe or a collection tank and the hot side reheats the air. Heat pump dryers typically utilize a fin and tube type of evaporator coil within a closed loop air passageway. As with condensation dryers, the known heat exchanger will not dry the internal air to as low a level of humidity as the ambient air. 
     With respect to ambient air, the higher humidity of the air used to dry the clothes has the effect of increasing drying times. However, because heat pump dryers conserve much of the heat of the air they use, the already-hot air can be cycled more quickly, possibly leading to shorter drying times than conventional dryers. In this way, not only does the dryer avoid the need for external duct routing, but this arrangement also conserves much of the heat within the dryer instead of exhausting the heat into the surroundings. Heat pump dryers can therefore use less than half the energy required by either condensation or traditional dryers. 
     This arrangement is more efficient than conventional dryers but is susceptible to associated problems of lint accumulation on the evaporator and at times even on the condenser causing lower heat transfer efficiency and difficulty in balancing the sealed system performance during the drying process. Additionally, the continuous change in a cooling load and a dehumidification load further causes inefficiencies with system balance. For at least the foregoing reasons, there remains a need for a more concise, efficient, and cost effective device and method for reducing energy consumption in a heat pump dryer by more efficiently using the enthalpy of a circulating fluid, an evaporator, and air within the device. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure relates to a heat pump based dryer comprising a housing receiving a drum for containing associated articles to be dried by air that flows along a pathway between an outlet and an inlet of the housing. A fluid is provided in the pathway to partially remove moisture from the air and a heat pump including a heat source or condenser is located at least partially within the pathway. A heat sink or evaporator is operatively adapted to the heat source to circulate a refrigerant therein and an enclosure at least partially containing the heat sink and is arranged to accept the fluid from the pathway to exchange heat with the heat sink and return the fluid to the pathway. 
     A pump may be provided to transport fluid between the enclosure and the pathway. Additionally, a collector may be operatively associated with the pathway to receive the fluid and the moisture removed from the air. The fluid and moisture removed from the air is then provided to a tank. The tank may be provided with a drain valve if too much fluid is provided to the tank. 
     In one embodiment, at least a portion of the fluid is provided within the pathway at a position adjacent to the outlet. Here the collector may include a generally cyclone shaped body adapted to receive the air and having a lint separator to separate lint from the air and to remove the moisture from the air to the tank. At least a portion of the fluid is then provided to the enclosure to exchange heat with the heat sink. 
     In another embodiment, the collector may include an evaporative exchange media having a plurality of perforations by which the fluid is provided on the evaporative exchange media to create a wet surface. The air within the pathway passes over the wet surface and separates the moisture from the air thereby collecting the fluid and moisture and providing it to the tank. A lint collector is provided upstream of the collector in this embodiment. 
     In each embodiment, the heat pump may further include an expansion valve and a compressor positioned in communication between the condenser and the evaporator whereby the expansion valve and compressor further manipulate the pressure and temperature of the refrigerant. 
     A controller may be provided for controlling the heat pump based dryer and may be associated with at least one sensor for measuring at least one variable output. The controller is configured to receive and process data representative of sensor readings measured by the sensor for selectively maintaining at least a temperature of the fluid to be below a dew point of the air at the outlet of the housing. The controller may also be configured to manipulate the outputs of a fan, the compressor, a pump, the drain valve or an auxiliary heater provided upstream of the condenser. More particularly, the sensors are adapted to identify the temperature of the fluid as it leaves the enclosure, the temperature of the air adjacent to the outlet and the relative humidity of the air adjacent to the outlet. These sensor locations help to identify the dew point of the air and temperature of the fluid for efficient use of the enthalpy of the air within the dryer. 
     In yet another embodiment, a method of drying articles with a heat pump based dryer is provided where the dryer includes a housing receiving a drum for containing associated articles to be dried and a condenser operatively associated with an evaporator for manipulating the temperature and pressure of a refrigerant, the evaporator including a return fluid heat exchanger. The method includes the steps of passing air of a predetermined temperature through the housing to dry the articles, adding a fluid to the air in a pathway, the fluid having a predetermined temperature below a dew point of the air for dehumidifying the air within the pathway and creating condensation and a cooler, dryer airflow, collecting the fluid and condensation within the pathway, providing at least a portion of the fluid and condensation to the evaporator return fluid heat exchanger, heating the air with the condenser within the pathway to a predetermined temperature and returning the fluid to the pathway and the air to the housing. 
     Additionally, the step of adding a fluid to the air may further include using an evaporative exchange media having a plurality of perforations whereby the fluid is first added to the evaporative exchange media creating a wet surface. The air then passes over the wet surface and at least partially separates the fluid and condensation from the air. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a first embodiment of a heat pump dryer. 
         FIG. 2  is a schematic view of the first embodiment of the heat pump dryer with the addition of a controller. 
         FIG. 3  is a schematic view of a second embodiment of the heat pump dryer. 
         FIG. 4  is a schematic view of the second embodiment of the heat pump dryer with the addition of a controller. 
         FIG. 5  is a schematic view of the second embodiment of the heat pump dryer. 
         FIGS. 6-9  show alternative embodiments of the heat pump dryer. 
         FIGS. 10-14  illustrate minor modifications to selected embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present disclosure is generally directed to a heat pump dryer and a method of drying articles with a heat pump based dryer that provide a more concise, efficient, and cost effective device and method for reducing energy consumption in a heat pump dryer by using the enthalpy of a circulating fluid, an evaporator, and air within the device. This dryer and method are directed at a home appliance for drying moist clothing articles. This dryer may include an individual dryer appliance or may comprise a combination washer/dryer appliance having a washing cycle prior to a drying cycle. 
       FIGS. 1-5  depict a schematic layout of various embodiments of the heat pump dryer  100 . The dryer  100  preferably comprises a housing  110  for receiving and enclosing a drum  120  having a cavity  125  therein. The housing  110  has a first end  130 , a second end  140  and at least one side  150  extending generally perpendicularly between the first and second ends  130 ,  140 . The first end  130  includes an access door  135  to allow selective access to the cavity  125  of the drum  120  and to maintain a secure and pressurized environment within the housing  110  when closed. The drum  120  has a generally cylindrical shaped body having a rim  160 , a base  170  and a generally continuous sidewall  180  extending in a general perpendicular direction between the rim  160  and the base  170 . The rim  160  focus an opening to provide access through the door to the cavity  125  for loading and unloading associated articles (e.g., laundry or clothing)  190  to be dried. 
     The base  170  of the drum  120  is operatively attached and preferably axially aligned to a motor  200 . The motor  200  is schematically depicted as being located outside the housing  110  however the motor  200  is often located within the housing  110 . When operated, the motor  200  rotates the drum  120  and the articles  190  within the cavity  125 . 
     An inlet  210  and an outlet  220  are provided for airflow communication with the articles  190  within the cavity  125  of the drum  120 . A pathway  230  extends between the outlet  220  and the inlet  210  as depicted in  FIGS. 1-5 . The pathway  230  generally comprises a ducted passage of a predetermined cross sectional area made of a suitable material such as foil, aluminum, plastic, metal or any combination therein to allow a pressurized airflow communication between the inlet  210 , outlet  220 , cavity  125  and other components of the heat pump dryer  100  as will be described more fully herein. Although the pathway  230  is schematically depicted as being located externally from the housing  110 , one skilled in the art will also recognize that the pathway  230  or portions thereof may be located in the housing, and all other schematically depicted components within the housing, thereby allowing ducted airflow communication within the dryer  100 . The internal cross sectional area of the pathway  230  may be shaped in any preferred manner such as a rectangle, a square, a circle, or an oval, so long as the cross sectional are is capable of allowing consistent flow of air as a function of a size of a load to be dried and an energy output of each component within the dryer  100 . 
     A first end  240  of the pathway  230  is attached to the outlet  220  while a second end  250  of the pathway is attached to the inlet  210 . Hot humid air  260  exits the outlet  220  and enters the pathway  230  through the first end  240 . A drying cycle of one embodiment of the heat pump dryer is depicted by  FIG. 1 . Here, a fluid  270  is introduced to the pathway  230  at a location adjacent to the outlet  220 . The fluid  270  generally comprises water of a reduced temperature as it enters the pathway  230 . However the fluid  270  but may also comprise a mixture of other materials generally known in the art that acts to prevent bacteria and mold growth or the corrosion of internal components. The fluid  270  may also comprise solvents or detergents that have evaporated from the associated articles  190  to be dried. The fluid  270  passes thru a spray nozzle  280  attached to the pathway  230  to allow the fluid  270  to comprehensively interact with the hot humid air  260 . The fluid  270  provided at the spray nozzle is at a decreased temperature that is below a dew point temperature of the hot humid air  260 . The interactions of the fluid  270  with the hot humid air  260  causes heat and mass transfer or a phase change whereby moisture is extracted by condensation from the hot humid air  260  by which a reduction in temperature of the hot humid air  260  is also achieved. The fluid  270  and condensation is then received in a collector  290  and combined to be circulated through one embodiment of a circulating fluid cycle  300  of the device  100  which will be described more fully herein. 
     The fluid  270  is introduced to the pathway  230  by the spray nozzle  280  having a temperature below the dew point temperature of the hot humid air  260  by which a heat and mass transfer interaction causes the hot humid air  260  to become cool dry air  310 . In one embodiment as depicted by  FIGS. 1 and 2 , the cool dry air  310  passes through a collector  290  that collects lint, airborne particles and the remaining fluid  270  to be circulated through the circulating fluid cycle  300 . Notably, the fluid  270  and condensate from the hot humid air  260  are combined and have an increased temperature as they are received by the collector  290 . The collector  290  may comprise a generally cyclone shaped body  320  that is operatively positioned and shaped to receive the cool dry air  310  downstream from the spray nozzle  280  while also collecting the remaining lint and fluid from the cool dry air  310 . The lint and fluid  270  is received at a lint separator  330  preferably located at a base  340  of the cyclone body  320  which allows an associated user to access the lint separator  330  to remove unwanted lint and particles from the collector  290 . However, the collector  290  is not limited to having a generally cyclone shaped body  320  and may also comprise other arrangements that are shaped to receive fluid  270  and unwanted lint from the cool dry air  310  such as a conventional mesh filter arrangement. 
       FIGS. 3-5  show another embodiment of the heat pump dryer  100  that uses a second circulating fluid cycle  600  by which the fluid  270  of decreased temperature enters the pathway  230  along a collector  610  comprising an evaporative exchange media  620 . The evaporative exchange media  620  may have a honeycomb shape media extended throughout a portion of the pathway  230  and operatively oriented to receive the fluid  270  thereby creating a wet surface  630  therein. The fluid  270  may be provided to the evaporative exchange media  620  through a spray nozzle  280  to comprehensively cover the media or the fluid may be drizzled thereon allowing the fluid  270  to soak or wick through the media  620 . Hot humid air  260  exits the outlet  220  and passes through a lint separator  330  prior to interacting with the wet surface  630  of the evaporative exchange media  620 . The evaporative exchange media  620  may comprise a desiccant material or other type material such as GLASdek® material supplied by Munters Corp. The lint separator  330  may comprise a generally cyclone shaped body  320  for lint collection at the base  340  or a conventional mesh filter accessible by an associated user. 
     The interaction at the evaporative exchange media  620  creates heat and mass transfer between the fluid  270  of a decreased temperature and the hot humid air  260  by which moisture or condensate is extracted from the air  260 . The hot humid air  260  passes the wet surface  630  and is modified to become a cold dry air  310  while the fluid  270  now has an increased temperature. The fluid  270  and condensation is then combined in the collector  610  to be circulated through the circulating fluid cycle  600  of the dryer  100 . 
     In each embodiment, the cool dry air  310  leaves the collector  290 ,  610  and interacts with a heat source  350  or condenser that is at least partially located within the pathway  230 . The heat source  350  is part of a heat pump or heat pump device  410  that is generally known in the art. The heat source  350  may comprise a coil or tube arrangement having heat transfer fins or other geometrical shapes to comprehensively interact with the cool dry air  310 . A refrigerant  400  is circulated through the heat pump  410 . The heat pump  410  also includes a heat sink  380  or evaporator, spaced from the pathway  230 , that is operatively associated with the heat source  350  located at least partially within the pathway  230 . Additionally, the heat pump  410  may also comprise an expansion valve  520  and a compressor  530  separately attached between the heat source  350  and the heat sink  380 . The expansion valve  520  is positioned to receive refrigerant  400  from the heat source  350  to be transferred to the heat sink  380 . The compressor  530  is positioned to receive refrigerant from the heat sink  380  to be transferred to the heat source  530 . Heat pumps are commonly known in the art and operate to manipulate the temperature and pressure of a refrigerant circulated therein to transfer heat between a heat sink and a heat source. 
     As the cool dry air  310  interacts with the heat source  350 , heat and mass transfer occurs and increases the temperature of the cool dry air  310  and decreases the temperature of the refrigerant  400  within the heat source  350 . The cool dry air  310  then becomes hot dry air  360  at this point in the drying cycle. Notably, the collector  290  and lint separator  330  arrangements upstream of the heat source  350  help to prevent the buildup of unwanted lint and airborne particles along a body of the heat source  350 . Buildup of lint above the surface of the heat source may substantially affect the heat transfer efficiency and overall balance of the dryer  100 . 
     The hot dry air  360  continues through the pathway and enters the inlet  210  to interact with the associated articles  190  to be dried. A fan  500  may be introduced to the pathway  230  to transfer air from the outlet  220  to the inlet  210  of the pathway  230 . The fan  500  is preferably located along the pathway  230  at a position downstream of the collector  290 ,  610  and upstream of the inlet  210  to allow for the proper transfer of air through the pathway  230 . An auxiliary heat source  510  may also be provided downstream of the heat source  350 , upstream of the inlet  210 , and within the pathway  230  for additional heat transfer to the hot dry air  360  as necessary for drying the associated articles  190 . 
     The fluid  270  received by the collector  290  is in communication with an enclosure  370  that at least partially contains the heat sink  380 . The fluid  270  may first be provided to a tank  390  for storage or to add or dispense fluid  270  within the circulating fluid cycles  300 ,  600 . The tank  390  may be provided with at least one drain valve  420  attached to an associated drain or an associated water source. The enclosure  370  may be arranged as a heat exchanger to transfer heat between the refrigerant  400  within the heat sink  380  and the fluid  270 . In the embodiments depicted in  FIGS. 1-2 , the enclosure  370  comprises a cross-direction heat exchanger whereby the fluid  270  and refrigerant  400  remain separated within the enclosure while they exchange heat. The fluid  270  of an increased temperature enters at a first port  430  adjacent a first end  450  of the enclosure  370  to interact with the heat sink  380  and exits at a second port  440  adjacent a second end  460  of the enclosure  370 . The fluid  270  exits the second port  440  having a decreased temperature as it transfers heat to the refrigerant  400  within the enclosure  370 . The direction of flow of the fluid  270  is opposite to the flow of the refrigerant  400  within the heat sink  380 . The refrigerant  400  of a decreased temperature enters at a third port  470  adjacent the second end  460  of the enclosure  370  to interact with the fluid  270  and exits at a fourth port  480  adjacent the first end  450  of the enclosure  370 . The refrigerant  400  exits the fourth port  480  having an increased temperature as heat is transferred from the fluid  270  to the refrigerant  400  within the enclosure  370 . 
     The enclosure  370  of each embodiment depicted in  FIGS. 3-5  comprises a common direction heat exchanger. Here, the fluid  270  of an increased temperature enters at a first port  435  adjacent the second end  460  of the enclosure  370  to interact with the heat sink  380  and exits at a second port  445  adjacent the first end  450  of the enclosure  370 . The fluid  270  exits the second port  445  having a decreased temperature as the fluid transfers heat to the refrigerant  400  within the enclosure  370 . The direction of flow of the fluid  270  is generally parallel to the flow of the refrigerant  400  within the heat sink  380 . The refrigerant  400  of a decreased temperature enters at a third port  475  adjacent the second end  460  of the enclosure  370  to interact with the fluid  270  and exits at a fourth port  485  adjacent the first end  450  of the enclosure  370 . The refrigerant  400  exits the fourth port  485  having an increased temperature as heat is transferred from the fluid  270  to the refrigerant  400  within the enclosure  370 . 
     The fluid  270  is circulated through the circulating fluid cycles  300 ,  600  by a pump  490  that is operatively attached to the enclosure  370  and the pathway  230 . The pump  490  of  FIG. 1-5  is preferably located downstream of the enclosure  370  and upstream of the spray nozzle  280  by which the fluid  270  leaves the enclosure  370  with a decreased temperature and re-enters the pathway  230  to interact with the hot humid air  260  exiting the cavity  125  of the drum  120 . The pump  490  may also be located upstream of the collectors  290 ,  610  or downstream of the tank  390  and/or enclosure  370  to introduce the required transfer pressure necessary to circulate the fluid  270  through the circulating fluid cycles  300 ,  600 . 
     As schematically shown in  FIGS. 2 and 4 , a controller  700  is provided in communication with a series of controllable components and sensors within the dryer  100 . In one embodiment, a first sensor  710  is provided along the pathway  230  adjacent the outlet  220  to indicate at least one variable output value of a temperature and a relative humidity of the hot humid air  260  as the air is exhausted from the outlet  220 . A second sensor  720  is provided at circulating fluid cycles  300 ,  600  to measure a variable output value of a temperature of the fluid  270  as the fluid exits the second ports  440  and  445  from the enclosure  370 . The variable outputs measured by the first sensor  710  and second sensor  720  allows the controller  700  to modulate controllable components of the dryer  100  to provide the fluid  270  to the pathway  230  at a temperature below the dew point temperature of the hot humid air  260 . As indicated by  FIGS. 2 and 4 , the controllable components may include the motor  200 , the compressor  530 , the pump  490 , the drain valve  420  and the fan  500 . Notably, as the temperature of the hot humid air  260  increases, the dew point temperature of the hot humid air  260  increases. Additionally, as the amount of moisture is reduced from the associated articles  190  or there otherwise exists a reduced load, the dew point of the hot humid air  260  also increases. In one embodiment, the fluid  270  is provided to the pathway  230  to interact with the hot humid air  260  when the temperature of the fluid  270  is at least 2-3 degrees Farenheit lower than the dew point of the hot humid air  260 . The fluid temperature is controlled by adaptively operating/balancing the heat pump and/or by using an external heat source/sink. Such an external heat sink could be ambient air or any available water/fluid or rinse water that may be available from the preceding wash cycle for subcooling/superheating. Likewise, the amount of fluid can be managed so that condensate is retained in the system from overflow and/or a heat content perspective. Still another option is to selectively use an auxiliary heat source  510  to occasionally manipulate the dew point from time to time during the whole cycle. This embodiment provides an efficient relationship for heat and mass transfer of the circulating fluid cycles  300 ,  600  within the dryer  100 . 
     The circulating fluid cycles  300 ,  600  may be provided to an individual heat pump dryer appliance as well as to a combination washer and dryer appliance. Further, these cycles may be provided without a rotating drum or be provided with a housing having a flat dryer body or a clothing rack. Selected aspects can also be utilized in dry cleaning applications where a number of washes are done with solvents. 
     In another embodiment of the present disclosure,  FIG. 5  depicts a supplemental enclosure  375  located within the pathway  230  and at least partially about the heat source  350 . The supplemental enclosure  375  provides heat transfer between the heat source  350  and a supplemental fluid  275  to reduce the amount of heat produced by the heat source  350  and transferred to the cool dry air  310 . The supplemental enclosure  375  is typically used when only a small amount of moisture remains within the associated articles  190  to be dried. This reduced load is typically encountered towards the later portion of the drying cycle by which the heat sink  350  produces excess heat resulting in an improper balance of the device  100 . The supplemental enclosure  375  and supplemental fluid  275  remove the excess heat from the device  100 . The supplemental enclosure is provided with at least one drain valve  425  that is controllable by the controller  700 . 
     An embodiment of the proposed device may also have a thermal insulation layer  702  applied over at least a partial surface on some of the pathway  230 , tank  390 , enclosure  370 , collector  290  and fluid conduits constituting the fluid cycles  300 , 600 , refrigerant conduits in order to contain undesired heat exchange between any of the fluid  270 , cool dry air  310 , hot dry air  360 , hot humid air  260 , refrigerant  400  and the corresponding adjacent ambient air ( FIGS. 6-8 ). In other embodiments ( FIGS. 8 and 9 ), the heat pump device  800  is one of a thermoelectric device, thermoacoustic device and a magnetocaloric device, and the heat sink  380  and heat source  350  are cold side heat exchanger  802  and hot side heat exchanger  804 , respectively ( FIG. 8 ). Further the heat pump device is configured to manipulate the temperatures of the cold side heat exchanger and hot side heat exchanger. Further the cold side heat exchanger  802  cools the circulating fluid that is subsequently used to cool and dehumidify the dryer air while the hot side heat exchanger  804  is used to reheat the cooled and dehumidified dryer air. In these embodiments too, a temperature or relative humidity sensor coupled with a suitable controller will be used to manipulate the temperatures of the cold side heat exchanger and hotside heat exchanger, as well as used to control the operation of various components such as pumps, valves, fans and the heat pump. 
     Thus, this disclosure relates to a heat pump system for drying clothes wherein an evaporator exchanges heat with a circulating fluid, which is subsequently used as a condensation means for removal of moisture or condensate from a moist dryer exhaust air, and using the enthalpy of the moist air to minimize energy requirements. 
     An evaporator cools the circulating fluid during a drying cycle and acts as a continuous source of low temperature fluid whereas the fluid temperature is lower than the dew point temperature of the moist dryer exhaust air. The fluid is then used in a heat and mass exchange process with the moist air such that the air is dehumidified due to condensation of airborne moisture. The circulating fluid carries the condensate to exchange heat with the evaporator. The heat of evaporation of the fluid is continuously reused for drying clothes in a heat pump based dryer. 
     In one embodiment, the circulating fluid of a reduced temperature is sprayed into the moist dryer exhaust air using a suitable spray nozzle to effect heat and mass exchange therein. A spray droplet separator and lint separator then removes the circulating fluid, condensate water and lint from the dryer air. 
     In another embodiment, a heat and mass exchange media may be used in such a way that the circulating fluid of a reduced temperature is gravitated through a honeycomb structured wicking media. The moist dryer exhaust air flows over a wetted surface of the wicking media to cause mass and heat exchange. Here, a separate lint collector such as a mesh filter or cyclone may be used upstream of the exchange media. 
     Each embodiment of the proposed device includes a heat pump with a heat exchanger acting as an evaporator wherein the refrigerant is circulated on one side of a heat exchanger wall and the circulating fluid is circulated on the other side. Further, the device may include at least one reservoir or tank and a controllable circulating pump to store and handle the required amount of circulating fluid. These components are controlled to maintain the desired temperatures of the fluid and air thereby facilitating an efficient and balanced performance. 
     A number of modifications may be made without departing from the scope and intent of the present disclosure. For example, portions of heat sink  380  and/or heat source  350  may be placed external to the enclosure and pathway  230 , respectively, to facilitate superheating/subcooling internally or with external sources. Alternatively in  FIG. 10 , flow through the heat sink may be in the counter-direction as opposed to the parallel direction shown in  FIG. 3 . Another change may include line  900  (shown in broken line in  FIG. 11 ) that extends from the controller  700  to drain valve  420  (otherwise similar to  FIG. 4 ) to control or maintain the fluid temperature below the dew point and to drain the collected condensate. Another change is shown in  FIG. 12  where flow through the heat sink is in the counter-direction when compared to  FIG. 4  and an additional connection is provided between compressor  530  and the controller  700 . In  FIG. 13 , modifications to the embodiment of FIG.  5  are illustrated to show an auxiliary condenser exchanging heat with an external fluid source (subcooling), whereas in  FIG. 14 , a modification to the  FIG. 6  embodiment provides flow in the counter-direction through the heat sink. 
     The disclosure has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the disclosure be construed as including all such modifications and alterations.