Patent Application
20220403582
The present disclosure relates to laundry and, more particular, to a dryer or combination washer/dryer machines that includes a sieve in the drying air circuit.
Dryers or combination washers/dryers exist in the art. Current vented dryers exhaust interior air to the exterior environment. This wastes the conditioned air inside the home. Additionally, current vented dryers do not reclaim the energy of evaporation by condensing it back to water again. The significant energy required for an open cycle that requires special high power circuits and plugs, combined with the requirement for a vent, limit where the appliance can be installed. Current heat pump dryers eliminate venting and reduce energy use by reclaiming the energy of condensation. However, they require a high powered compressor and often take considerable time to dry clothes.
Accordingly, it would be desirable to have a dryer or combination washer/dryer with a drying air circuit that increases efficiency even beyond that of a heat pump dryer. Likewise, it is desirable for a dryer or combination washer/dryer machine to be able to run on conventional low voltage circuits. Additionally, it would be desirable to eliminate venting into the outside air.
Accordingly, the present disclosure provides a dryer or combination washer/dryer machine that overcomes the above deficiencies by using a molecular sieve and a compressor deployed in a novel way to separate some of the water vapor from the drying air circuit. The highly concentrated water vapor drawn through the molecular sieve is compressed then condensed on the drum to reclaim both the energy of compression and the energy of condensation. This energy is transferred through the inner wall of the drum to the wet clothing, creating additional evaporation from the clothing. The reduced humidity airflow that had passed by the sieve then enters back into the drum where it can pick up more moisture and repeat the drying circuit.
This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope nor all of its features.
Accordingly, to an object of the disclosure, a combination washer/dryer machine comprises a rotating double-walled drum inside a tub with an access door to insert and remove clothing. A blower recirculates drying air in a circuit. The clothes drying circuit includes an inlet and an outlet into and out of the tub. A conduit connects the inlet and the outlet. A molecular sieve is positioned in the conduit so that the humid air passes by, but not through the sieve membrane. The sieve has pores that are sized to enable water molecules to pass through but it excludes all but a small fraction of a percent of the larger molecules in the air. Thus, this reduces relative humidity in the drying airflow. The inlet of a compressor is connected to the back side of the molecular sieve membrane. The compressor generates a vacuum to draw the water molecules through the molecular sieve into the compressor. During compression, the highly concentrated water vapor becomes superheated steam. The compressor may be a turbo compressor. The compressed water vapor is passed through an air exchange cooler to remove excess heat. The compressed water vapor is passed into the space between the doubled walls of the drum. Here the water vapor is cooled and condensed. The energy of condensation is passed through the inner wall to the clothing to evaporate more water from the clothing. An electrical heater inside the drum can heat the system to operating temperature. A positive displacement pump removes the condensate and non-condensable gasses that accumulate between the walls of the drum. The condensate is stored in a reuse tank, and the non-condensable gasses dissipate into the surrounding air.
Accordingly, to another object of the disclosure, a dryer machine comprises a rotating double-walled drum with an access door to insert and remove clothing. A blower recirculates drying air in a circuit. The clothes drying circuit includes an inlet and an outlet into and out of the drum. A conduit connects the inlet and the outlet. A molecular sieve is positioned in the conduit so that the humid air passes by, but not through the sieve membrane. The sieve has pores that are sized to enable water molecules to pass through but it excludes all but a small fraction of a percent of the larger molecules in the air. Thus, this reduces relative humidity in the drying airflow. The inlet of a compressor is connected to the back side of the molecular sieve membrane. The compressor generates a vacuum to draw the water molecules through the molecular sieve into the compressor. During compression, the highly concentrated water vapor becomes superheated steam. The compressor may be a turbo compressor. The compressed water vapor is passed through an air exchange cooler to remove excess heat. The compressed water vapor is passed into the space between the doubled walls of the drum. Here the water vapor is cooled and condensed. The energy of condensation is passed through the inner wall to the clothing to evaporate more water from the clothing. An electrical heater can heat the system to operating temperature. A positive displacement pump removes the condensate and non-condensable gasses that accumulate between the walls of the drum. The condensate is drained in a reuse tank, and the non-condensable gasses dissipate into the surrounding air.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations and are not intended to limit the scope of the present disclosure.
Example embodiments will now be described more fully with reference to the accompanying drawings.
Turning to
The conduit 24 includes a sieve 30. The sieve 30 is generally an assembly of an arrangement of a large surface area of membranes 36 with molecular sieve properties. The molecular sieve membranes 36 in sieve 30 filters water vapor from the humid air exhausted from the tub 14. The sieve 30 enables smaller water molecules to pass through the sieve 30 while larger molecules are blocked. The drying airflow has water molecules removed by the sieve 30 without changing its temperature and pressure by creating a partial pressure differential of water vapor across the membranes 36. As a non-limiting example, the air exiting the enclosure at 22 may be 95% relative humidity at 55 C. At these conditions, the partial pressure of water in air would be about 15.0 kPa as it enters the sieve 30. The compressor suction in conduit 52 may lower the pressure of the nearly 100% water vapor to 6.3 kPa on the backside of the membranes 63. This creates the partial pressure difference that draws water vapor through the molecular sieve membranes 36. Because pore size in the membranes 36 cannot be controlled to perfection, some small amount of air, less than 0.1%, can be drawn through the membrane 36 in sieve 30 along with the water vapor into conduit 52.
A turbocompressor 32 is coupled with the backside of the sieve 30 along the water vapor path 18 by conduit 52. The turbocompressor 32 may compress this concentrated water vapor to 15.8 kPa superheated steam at approximately 139° C. at the discharge into water vapor path 18. Further along the water vapor path 18 the compressed water vapor may pass through a cooler 55 where excess heat from compression is removed prior to entry into the dual-walled drum 12. At this 15.8 kPa pressure, steam condenses into water at 55 C. This enables the condensation to occur between the walls of dual-walled drum 12 at temperatures that will not damage clothing.
As the drying airflow passes through the sieve 30 the humidity ratio may be reduced by 20% to 30% with only a slight drop in temperature. Thus, without the need to add heat, the drier air enters the tub 14 ready to accept more evaporated moisture into the air generated by the heat of condensation transferred through the drum walls.
A variable speed blower 38 is positioned in the conduit 24. The variable speed blower 38 provides for the movement of the drying airflow through the drying circuit 16. The speed can be adjusted by the machine controls with input from sensor(s) placed in conduit 24 to vary drying circuit airflow to maintain a high relative humidity even when drying rates diminish toward the end of the cycle. Sensors may be Relative Humidity or ‘temperature or the like. This is necessary to get the maximum partial pressure of water in the air circuit that drives water through the membranes 36.
An electric heater 40 is positioned in the tub 14 sump. The electric heater 40 is used during startup to warm the system to the operating temperature of 55 C needed to run the drying circuit. It may also be used as supplemental heat as needed.
The water vapor path 18 is positioned within a housing of the machine 10. The water vapor path 18 includes the sieve 30, compressor 32, cooler 55 and double walled drum 12. The condensate path includes tube 56, displacement pump 42, tube 58 and water reuse tank 44.
The double walled drum 12 is like that disclosed in U.S. Patent Application No. 2019/0292072 entitled “Vapor Compression Distillation Assembly” that is assigned to the assignee of the present application. This patent also describes a method to collect and remove condensate and non-condensable gasses from between the walls of the drum 12. Here, the water vapor condenses on the innermost wall of the double walled drum 12 creating heat via the heat of condensation. This heat of condensation is conducted into the air and clothing or material within the drum 12 through the wall. The temperature in the drum is defined by the pressure within the walls which, in turn, defines the temperature of condensation between the walls and inside the drum. The pressure is sustained at a vacuum of 15.8 kPa by the continued condensation since the specific volume is reduced several orders of magnitude when it changes phase. The condensate and accumulated non-condensable gasses exit the double drum 12 via conduit 56. The conduit 56 is connected with the displacement pump 42. The displacement pump 42 evacuates the condensate and non-condensable gases from 15.8 kPa up to the atmospheric pressure (101 kPa) in the reuse tank 44 through conduit 58. The water reuse tank 44 includes a vent 62 that enables the non-condensable gasses to vent to atmosphere.
Prior to the dry program the combination washer/dryer machine is operated to wash the clothes within the drum 12 using a typical wash program. At the conclusion of the wash program, after the final spin, the system, including the wet clothing, the drum, and the circulating air are warmed to a desired temperature. Generally, the temperature of the drying air flow is between 40° to 60° C. In the present example, the operating air is approximately 55° C. At this point the compressor 32 is turned on to begin the drying process which continues until the clothing is dry.
The sieve 30, via membranes 36, withdraws water and air from the drying airflow. The water and air withdrawn pass into a collection area and into the conduit 52 connected with the compressor 32. The water vapor in the conduit 52 is at approximately 55° C. at a pressure of 6.3 kPa with air at less than 0.1%. The compressor 32 compresses the water vapor to a temperature around 139° at approximately 15.8 kPa. The compressor 32 may be a variable speed compressor that is controlled by algorithm in the machine controls and sensors in conduit 52 and/or 54 to maintain the pressure on the backside of the membranes 36 and between the double walls of drum 12. The steam continues to pass through the conduit 54 through the cooler 55 where excess superheat is removed prior to entrance between the walls of the double walled drum 12. The cooler 55 includes a heat exchanger 64 that is placed on the conduit 54 to prevent overheating. Accordingly, a fan 62 may be present to enhance cooling. Fan 62 may be a variable speed fan also controlled by either a thermostat or machine control algorithm to vary superheat removal based on rate of water vapor removed in molecular sieve 30. The water vapor or steam condenses between the walls of the double walled drum 12 where condensation occurs at nonlimiting example conditions of approximately 15.8 kPa at 55° C. After the heat of condensation has been moved into the clothing and air within the drum 12, the condensate and non-condensable gasses that collect between the double walls of tub 12 are removed by the displacement pump 42 through conduit 55. The air that is present in the condensate vents to atmosphere via the water reuse tank vent 62.
As the clothing tumbles in the dual-walled drum 12, it absorbs the energy of condensation through the inner wall of the dual-walled drum 12 at approximately 55° C. causing water to evaporate from the clothing. This water vapor penetrates the clothing and exits out of the open end of the drum into the tub 14 where it mixes with the recirculating drying air entering the tub 14 through inlet 20.
Turning to
The dryer 100 includes elements like a dual-walled drum 12, cabinet 102 and remaining controls, actuators, motors and other devices typical in a laundry appliance. The disclosure focuses on the heating and drying of the clothes or textiles within the drum 12 during the drying cycle.
The conduit 24 includes a sieve 30. The sieve 30 is generally an assembly of an arrangement of a large surface area of membranes 36 with molecular sieve properties as described above. The molecular sieve membranes 36 in sieve 30 filters water vapor from the humid air exhausted from the drum 12. The sieve 30 enables smaller water molecules to pass through the sieve 30 while larger molecules are blocked. The drying airflow has water molecules removed by the sieve 30 without changing its temperature and pressure by creating a partial pressure differential of water vapor across the membranes 36. As a non-limiting example, the air exiting the outlet at 106 may be 95% relative humidity at 55 C as discussed above. At these conditions, the partial pressure of water in air would be about 15.0 kPa as it enters the sieve 30. The compressor suction in conduit 52 may lower the pressure of the nearly 100% water vapor to 6.3 kPa on the backside of the membranes 63. This creates the partial pressure difference that draws water vapor through the molecular sieve membranes 36. Because pore size in the membranes 36 cannot be controlled to perfection, some small amount of air, less than 0.1%, can be drawn through the membrane 36 in sieve 30 along with the water vapor into conduit 52.
A turbocompressor 32 is coupled with the backside of the sieve 30 along the water vapor path 18 by conduit 52. The turbocompressor 32 may compress this concentrated water vapor to 15.8 kPa superheated steam at approximately 139° C. at the discharge into water vapor path 18. Further along the water vapor path 18 the compressed water vapor may pass through a cooler 55 where excess heat from compression is removed prior to entry into the double walled drum 12. At this 15.8 kPa pressure, steam condenses into water at 55 C. This enables the condensation to occur between the walls of drum 12 at temperatures that will not damage clothing.
As the drying airflow passes through the sieve 30 the humidity ratio may be reduced by 20% to 30% with only a slight drop in temperature. Thus, without the need to add heat, the drier air enters the tub 14 ready to accept more evaporated moisture into the air generated by the heat of condensation transferred through the drum walls.
A variable speed blower 38 is positioned in the conduit 24. The variable speed blower 38 provides for the movement of the drying airflow through the drying circuit 16. The speed can be adjusted by the machine controls with input from sensor(s) placed in conduit 24 to vary drying circuit airflow to maintain a high relative humidity even when drying rates diminish toward the end of the cycle. Sensors may be Relative Humidity or ‘temperature or the like. This is necessary to get the maximum partial pressure of water in the air circuit that drives water through the membranes 36.
An electric heater 108 is positioned adjacent the drum 12. The electric heater 108 is used during startup to warm the system to the operating temperature of 55 C needed to run the drying circuit. It may also be used as supplemental heat as needed. The heater could also be a gas heater to heat the drum 12.
The water vapor path 18 is positioned within a cabinet 102 of the machine 100. The water vapor path 18 includes the sieve 30, compressor 32, cooler 55 and double walled drum 12. The condensate path includes tube 56, displacement pump 42, tube 58 and water reuse tank 44.
The double walled drum 12 is like that disclosed in U.S. Patent Application No. 2019/0292072 entitled “Vapor Compression Distillation Assembly” that is assigned to the assignee of the present application. This patent also describes a method to collect and remove condensate and non-condensable gasses from between the walls of the drum 12. Here, the water vapor condenses on the innermost wall of the double walled drum 12 creating heat via the heat of condensation. This heat of condensation is conducted into the air and clothing or material within the drum 12 through the wall. The temperature in the drum is defined by the pressure within the walls which, in turn, defines the temperature of condensation between the walls and inside the drum. The pressure is sustained at a vacuum of 15.8 kPa by the continued condensation since the specific volume is reduced several orders of magnitude when it changes phase. The condensate and accumulated non-condensable gasses exit the double drum 12 via conduit 56. The conduit 56 is connected with the displacement pump 42. The displacement pump 42 evacuates the condensate and non-condensable gases from 15.8 kPa up to the atmospheric pressure (101 kPa) in the reuse tank 44 through conduit 58. The water reuse tank 44 includes a drain 110 and a vent 62 that enables water to drain out of the tank 44 and the non-condensable gasses to vent to atmosphere.
After washing clothing, the wet clothing is placed into the drum and the circulating air in the dryer is warmed to a desired temperature. Generally, the temperature of the drying air flow is between 40° to 60° C. In the present example, the operating air is approximately 55° C. At this point the compressor 32 is turned on to begin the drying process which continues until the clothing is dry
The sieve 30, via membranes 36, withdraws water and air from the drying airflow. The water and air withdrawn pass into a collection area and into the conduit 52 connected with the compressor 32. The water vapor in the conduit 52 is at approximately 55° C. at a pressure of 6.3 kPa with air at less than 0.1%. The compressor 32 compresses the water vapor to a temperature around 139° at approximately 15.8 kPa. The compressor 32 may be a variable speed compressor that is controlled by algorithm in the machine controls and sensors in conduit 52 and/or 54 to maintain the pressure on the backside of the membranes 36 and between the double walls of drum 12. The steam continues to pass through the conduit 54 through the cooler 55 where excess superheat is removed prior to entrance between the walls of the double walled drum 12. The cooler 55 includes a heat exchanger 64 that is placed on the conduit 54 to prevent overheating. Accordingly, a fan 62 may be present to enhance cooling. Fan 62 may be a variable speed fan also controlled by either a thermostat or machine control algorithm to vary superheat removal based on rate of water vapor removed the in molecular sieve 30. The water vapor or steam condenses between the walls of the double walled drum 12 where condensation occurs at nonlimiting example conditions of approximately 15.8 kPa at 55° C. After the heat of condensation has been moved into the clothing and air within the drum 12, the condensate and non-condensable gasses that collect between the double walls of tub 12 are removed by the displacement pump 42 through conduit 55. The air that is present in the condensate vents to atmosphere via the water reuse tank vent 62.
It is noteworthy that the embodiments presented herein do not require the circulated drying air to carry in the heat of vaporization that passes through the clothing thus eliminating the significant amount of air that must pass through the drum and clothing in typical dryers. Rather, in at least one of the embodiments presented herein, the water vapor is generated inside the dual-walled drum 12 when the heat of condensation is transferred through the wall and heats the clothing to evaporate water. Because the heat transferred to the clothes comes from the dual-walled drum 12 and not the circulating air, this enables the ability for more clothing to be placed in the dual-walled drum 12 than in present machines without compromising the drying efficiency. Due to the expansion of the water that is coming off the clothing which is being dried when evaporating into a gas phase, the water vapor will move through the clothing to exit the dual-walled drum 12, thereby resulting in significant water vapor flow from the open end of the dual-walled drum 12. This water vapor flow is mixed with the circulating air before entering the molecular sieve. Having either a tub enclosure or bulkhead with seals to aid in retaining the circulating air will aid in this mixing, along with added mixing due to the flow facilitated by the blower 38. Such a setup may also enable efficient dry capabilities without the need for a large drum, or otherwise enables a larger load of clothing in a typical sized drum. It also permits more efficient drying in a combination washer/dryer unit wherein a challenge tends to be reconciling the mismatch between the larger size of the drum needed for washing with the smaller size needed for enhancing tumble dry performance.
The foregoing description of the embodiments has been provided for purposes of illustration and description in the context of a combination washer/dryer. It is not intended to be exhaustive or to limit the disclosure from use in other embodiments such as a standalone dryer. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
