EP3388571B1

EP3388571B1 - Clothes drying appliance

Info

Publication number: EP3388571B1
Application number: EP17382195.0A
Authority: EP
Inventors: Pilar Balerdi Azpilicueta; Jose Antonio Ruiz Bermejo; Roberto San Martin Sancho
Original assignee: BSH Hausgeraete GmbH; BSH Electrodomesticos Espana SA
Current assignee: BSH Hausgeraete GmbH; BSH Electrodomesticos Espana SA
Priority date: 2017-04-10
Filing date: 2017-04-10
Publication date: 2020-07-29
Anticipated expiration: 2037-04-10
Also published as: PL3388571T3; EP3388571A1

Description

The invention relates to a clothes drying appliance, comprising a process air channel and a heat pump, wherein an evaporator and a condenser of the heat pump are accommodated within the process air channel. The invention is particularly useful for household appliances, in particular open-loop or closed-loop drying appliances.
Clothes drying appliances using a heat pump are generally known. For example, EP 1 964 965 A1 discloses a household appliance comprising a drying chamber for drying wet articles therein, a process air loop for circulating process air to dry the articles and a heat pump. Said heat pump comprises a pumping loop containing a pumping fluid to be circulated through said pumping loop, an evaporator heat exchanger for transferring heat from the process air into said pumping fluid by evaporating said pumping fluid, a liquefier heat exchanger for transferring heat from said pumping fluid to the process air by liquefying said pumping fluid, a compressor for compressing the pumping fluid and driving the pumping fluid through said pumping loop, and a nozzle for decompressing said pumping fluid.
In another example, EP 2 253 757 A1 discloses a household appliance having a housing and comprising within said housing a control unit, a drying chamber for containing articles to be dried, a closed-loop process air channel having a first blower operable by said control unit for conveying process air along the articles to effect drying, a heat pump unit operable by said control unit for extracting humidity from the process air, a condensate collector for collecting condensate thus formed by the heat pump unit and means for cooling at least one component of said heat pump unit including a second blower operable by said control unit, said means for cooling including an open-loop cooling channel having said second blower for conveying cooling air from outside said housing to said at least one component. Further, said cooling channel comprises a guide including said second blower, said guide connecting an inlet in said housing to said at least one component for cooling. The housing has a multiplicity of outlets allowing cooling air to flow out of said housing.
WO 2013/144875 A1 discloses a heat exchanger that comprises at least one set of pipes, each set of pipes comprising at least two pipes, wherein the pipes are mechanically connected by at least one connection structure. At least two pipes are made from different metals having a different thermal expansion coefficient; at least two of the pipes having a different thermal expansion coefficient are joined by a soldered joint or by a brazed joint. At the joint of the two pipes, the pipe made of the metal having a lower thermal expansion coefficient is inserted into the pipe made of the metal having a higher thermal expansion coefficient. The invention also relates to a household appliance, in particular clothes treatment appliance, comprising at least one such heat exchanger, and a method for manufacturing such heat exchanger.
WO 2015/068092 A1 discloses a heat pump P that is designed for a household appliance, in particular laundry treatment appliance, and comprises a rotary compressor, a condenser, a restrictor, and an evaporator, wherein the condenser is of an expanded tube-and-fin type with the tubes having an outer diameter dc of less than 7 mm and wherein the roller has a height-to-radius ratio of 1.4 to 1.2. A household appliance, in particular a laundry treatment appliance, comprises such heat pump.
EP 2 987 904 A1 discloses a front-loading tumble dryer which comprises a housing that accommodates a rotatable drum and a heat pump, the drum comprising a rear wall having an inlet opening for process air, and the heat pump comprising a condenser, wherein the condenser is at least partially positioned between the rear wall of the drum and a rear wall of the housing.
WO 2005/036079 A2 discloses a heat pump apparatus which comprises a heat pump cycle in which a refrigerant circulates through a compressor, a radiator, a throttle apparatus and an evaporator in this order, and an air duct which envelops the radiator and the evaporator, and which dehumidifies air absorbed from an object-to-be-dried by means of the evaporator and which heats the air by means of the radiator. A rectifier apparatus is provided at an inlet of the air duct.
EP 2 341 179 A1 discloses a home laundry drier comprising an outer casing and inside the casing, a laundry drying container for housing the laundry to be dried, and a hot-air generator for circulating a stream of hot air inside the laundry drying container; said hot-air generator being provided with a heat-pump assembly having a refrigerant compressing device which is connected to a supporting wall of the casing via one or more vibration dampers.
Presently, the heat pump is often implemented in such way that its components are positioned on a base module. The base module is a plastic structure that constitutes or sits on a bottom of the respective clothes drying appliance. When all the heat pump components (e.g. comprising a compressor, heat exchangers, pipes for working fluid (refrigerant), a capillary, and eventually a dehydrator filter) are assembled on top of the base module, this assembly may also be called a bottom group. Presently, a position of the compressor on the bottom group is in a corner of the bottom group outside the air flow channel. The heat exchangers, on the other hand, are positioned inside the airflow conduction. Furthermore, the compressor is aligned in a vertical manner, i.e., with its longitudinal axis being oriented vertically or nearly vertically. An additional fan is positioned in front of the compressor for its cooling.
It is the object of the present invention to at least partially overcome the problems associated with the prior art. It is a particular object of the present invention to provide a clothes drying appliance comprising a heat pump that has an improved energy performance, that is particularly cost efficient, and/or that is of a particularly compact design.
The object is achieved according to the features of the independent claims. Advantageous embodiments can be found, e.g., in the dependent claims and/or in the description.
The object is achieved by a clothes drying appliance, comprising a process air channel and a heat pump, wherein an evaporator and a condenser of the heat pump are accommodated within the process air channel, with the condenser accommodated downstream of the evaporator with respect to a direction of a process air flow and wherein a compressor of the heat pump is accommodated within the process air channel downstream of the evaporator.
Typically, the condenser is being positioned downstream of the evaporator. The evaporator is used to cool down warm and moist process air flowing in from a clothes receptacle, e.g. a drum. The evaporator causes moisture of the process air to condensate. Downstream the evaporator, the resulting cooler and drier process air flows through the condenser where it is heated up and then re-enters the clothes receptacle as warm and dry air.
Such a clothes drying appliance gives the advantage that the heat produced by operating the compressor can be used to directly heat up process air flowing around the compressor. This improves an energy performance of heat pump dryer. Such an arrangement also improves cooling of the compressor since the process air flowing around the compressor is relatively cool.
Thus, in one variant, there is the advantage that a dedicated fan to cool the compressor may be dispensed with. This, in turn, gives the advantage that space requirements and costs can be reduced. Because of the improved energy performance, a smaller compressor may be used.
Also, the compressor is placed nearer to the heat exchangers which position enables reducing a length of the working fluid pipes. This, in turn, enables reducing the amount of refrigerant and thus of costs. Furthermore, the position between the heat exchangers enables a particularly compact design.
Locating the compressor inside the process air channel gives the further advantage that space on the bottom group until now used for accommodating the compressor is free to be used to allocate other component. This also supports a compact design.
The clothes drying appliance may be a clothes dryer or a washing / drying combination ("washer dryer").
Additionally to the evaporator, the condenser and the compressor, the heat pump comprises an expansion valve / capillary, eventually a dehydrator filter etc. The compressor may be a rotary compressor.
It is an embodiment that the compressor is accommodated within the process air channel between the evaporator and the condenser.
According to the invention the compressor is a horizontal rotary compressor. This gives the advantage that a height of the compressor is lower than for a vertically oriented compressor and that the compressor fits into a space not higher or at least not considerably higher than a height of the heat exchangers. This, in turn, improves an air flow around the full length of the compressor and thus an effective heat transfer from the compressor to the process air. Therefore, it is one advantageous embodiment that a height of the compressor does not exceed a height of the heat exchangers.
A "horizontal rotary compressor" may be defined as a rotary compressor having a longitudinal axis that is more inclined or directed towards a horizontal plane than a vertical plane. In analogy, a "vertically oriented compressor" or vertical compressor may be defined as a compressor having a longitudinal axis more aligned with the vertical plane than the horizontal plane. The horizontal rotary compressor has similar performance as the vertical rotary compressor, and its working principle is the same. Differences between a vertical compressor and a horizontal compressor may exist in the oil pumping system, in a position of a suction pipe / accumulator, and / or in a position of a discharge pipe.
It is an embodiment that a longitudinal axis of the compressor deviates not more than 10°, in particular not more than 5°, from a horizontal plane. This gives a particularly advantageous compact design.
It is an embodiment that the compressor is oriented in alignment with the process air channel. This keeps a pressure loss caused by the compressor low. That the compressor is oriented in alignment with the process air channel may comprise an arrangement in which the longitudinal axis of the compressor and a flow direction of the process air / a direction of the process air channel are within the same vertical plane. This may include that the longitudinal axis of the compressor and the flow direction of the process air / the direction of the process air channel are aligned in parallel if viewed from above.
It is another embodiment that the compressor is transversely oriented with respect to the process air channel. This enables a particularly high energy transfer. That the compressor is transversely oriented with respect to the process air channel may comprise an arrangement in which a vertical plane comprising the longitudinal axis of the compressor and a vertical plane comprising a flow direction of the process air / a direction of the process air channel are perpendicular to each other. This may include that the longitudinal axis of the compressor and the flow direction of the process air / the direction of the process air channel are perpendicular if viewed from above.
According to the invention the evaporator is realized as a first finned tube-type heat exchanger and the condenser is realized as a second finned tube-type heat exchanger. A finned tube-type heat exchanger may be implemented such that a stack of fins is penetrated by a set of pipes. Such a heat exchanger is very compact and efficient. The fins act as a heat exchange structure for the pipes. Within the finned tube-type heat exchanger, the pipes are preferably oriented in the same direction to achieve a particularly compact form. In particular, the heat exchanger may be a working fluid / process air heat exchanger that comprises one set of pipes to transport a working fluid of the heat pump.
It is an embodiment that a tube of at least one of the heat exchangers has at least one aluminium tube section (e.g. a pipe and/or an elbow section) and at least one copper tube section. Alternatively, the tube may be entirely made of copper or entirely made of aluminium. The use of copper gives the advantage of a particularly effective heat transfer which can be used to reduce a size (volume) of the heat exchanger while maintaining a heat exchange capacity. The use of aluminium gives the advantage of a particularly cost-effective and lightweight heat exchanger. Additionally, the use of copper enables using tube sections having a smaller wall thickness than that of aluminium tube sections. This can be used to employ tube sections also having a smaller outer diameter which may lead to an especially compact design. One advantageous embodiment is achieved when an outer diameter of the tube sections is 5 mm or smaller.
The same advantages are achieved if a fin spacing of the least one of the heat exchanger is smaller than 2.5 mm. Advantageously, the fin spacing is 2.2 mm or less, in particular 1.5 mm or less. A smaller fin spacing increases a surface area available for exchanging heat but causes a higher flow resistance. Having the compressor placed between the heat exchangers already slows down the flow velocity of the process air towards the condenser such that a higher flow resistance caused by a denser fin arrangement of the condenser does not have such a great effect. Thus, because the velocity of the process air flowing towards the evaporator is not reduced by the compressor, it is advantageous that the fin spacing of the evaporator is larger than the fin spacing of the condenser. In particular, a fin spacing of the evaporator may be approx. 2.2 mm and a fin spacing of the condenser may be approx. 1.5 mm.
According to the invention, the fin spacing of the evaporator is smaller than the fin spacing of the condenser.
It is an embodiment that an extend ("depth") of each of the heat exchangers along the process air channel is 70 mm or smaller. This enables a wide range of compressors to be inserted between the heat exchangers while maintaining a compact design.
According to the invention a number of rows of linear tube sections along the process air channel is the same for the condenser and the evaporator while a number of linear tube sections along a vertical direction is greater for the condenser. This gives the advantage that a heat exchange capacity of the condenser may be greater than a heat exchange capacity of the evaporator while maintaining the same depth. For example, the condenser may use seven tubes per row while the evaporator uses five tubes per row. This also results in a greater vertical height of the condenser, e.g. of approx. 135 mm compared to approx. 95 mm of the evaporator. Alternatively, the heat exchangers may have the same height but different depth or the same height and the same depth but different numbers of pipes. For example, different tubes may be employed.
It is an embodiment that the appliance is a household appliance in which the process air channel is part of a closed-loop process air circuit, the process air circuit also comprising a rotatable drum for holding clothes. An air outlet of the drum is connected to one end of the process air channel and another end of the process air channel is connected to an air inlet of the drum. Regarding a flow direction of the process air, the condenser is positioned downstream of the evaporator.
Alternatively, the appliance is a household appliance in which the process air channel is part of an open-loop process air circuit. In this case, the air inlet and the air outlet of the drum are connected to the ambient. An air inlet section positioned between an air inlet opening of this section and the air inlet of the drum may comprise a heat exchanger for heating the incoming ambient / fresh air, e.g. a condenser of a heat pump. An air outlet section between the air outlet of the drum and an air outlet opening to the ambient may comprise a heat exchanger for cooling down the outgoing warm and moist air, e.g. an evaporator of a heat pump.
In case of an open-loop process air circuit, the compressor may be positioned in the air inlet section between the condenser and the drum. Alternatively, the compressor may be positioned between the air inlet opening of the air inlet section and the condenser. Alternatively, the compressor may be positioned in the air outlet section between the evaporator and the air outlet opening to heat up the air flow before sending it to the ambient.
The above described features and advantages of the invention as well as their kind of implementation will now be schematically described in more detail by at least one embodiment in the context of one or more figures.

Fig.1: shows a top-down view on a section of a process air channel of a clothes drying appliance according to a first embodiment comprising an evaporator, a compressor, and a condenser of a heat pump;
Fig.2: shows a side view on the compressor of Fig.1;
Fig.3: shows a frontal view on the compressor of Fig.2; and
Fig.4: shows a top-down view on a section of a process air channel of a clothes drying appliance according to a second embodiment comprising the evaporator, the compressor, and the condenser of the heat pump.

Fig.1 shows a top-down view on a section of a process air channel 1 of a clothes drying appliance 2 comprising an evaporator 3, a compressor 4, and a condenser 5 of a heat pump 3 to 5 (with its expansion valve not shown). Thus, the compressor 4 is accommodated within the process air channel 1 in a gap between the evaporator 3 and the condenser 5. The evaporator 3 is implemented as a first finned tube-type heat exchanger to transport heat from the process air P to the working fluid of the heat pump 3 to 5. The condenser 5 is implemented as a second finned tube-type heat exchanger to transport heat from the working fluid of the heat pump 3 to 5 to the process air P. The components 1, 3 to 5 are fixed at a base module of a plastic bottom group (not shown).
The evaporator 3, the compressor 4, and the condenser 5 are positioned in series in a general flow direction of process air P through this section, as indicated by the arrows. Within the process air channel 1, the process air P flows from an air outlet opening of a clothes drum (not shown, e.g. a horizontally rotatable drum, for containing clothes to be dried) through the evaporator 3, along the compressor 4, through the condenser 5 and back into the drum through an air inlet opening. The motion of the process air P is caused by a fan (not shown). The condenser 5 is this positioned downstream of the evaporator 3.
The evaporator 3 is used to cool down warm and moist process air flowing in from a clothes receptacle, e.g. a drum. The evaporator 3 causes moisture of the process air P to condensate. Therefore, the process air P emerging from the evaporator is relatively cool and dry. The process air P is now to be heated and re-introduced into the drum to again take up moisture from wet clothes contained in the drum.
To this effect, the process air P leaving the evaporator 3 then flows around the compressor 4. The compressor 4 has a warm exterior due to its operation as a drive of the heat pump 3 to 5. Thus, the process air P is warmed up due to a heat transfer from the compressor 4 to the process air P. This warmed-up process air P then flows through the condenser 5 to be heated even further. The now warm and dry process air P is then re-introduced into the drum.
The compressor 4 is a horizontal rotary compressor, as also shown in Fig.2 . The horizontal rotary compressor 4 has a longitudinal axis L that includes an angle ϕ of 5° with a horizontal plane H. The horizontal rotary compressor 4 has a structure similar to that of a vertical compressor. As shown in Fig.3 , horizontal rotary compressor 4 has a suction pipe 6 and a discharge pipe 7 for working fluid.
In the clothes drying appliance 2, the compressor 4 is oriented in alignment with the process air channel 1. That is, the longitudinal axis L of the compressor 4 and the flow direction of the process air P and the direction of the process air channel 1, respectively, are aligned in parallel if viewed from above, as is shown in Fig.1. This keeps low a pressure loss caused by the presence of the compressor 4.
For a high heat transfer effectiveness and a low flow resistance, a fin spacing of the condenser 5 (e.g. 1.5 mm) is smaller than a fin spacing of the evaporator 3 (e.g. 2.2 mm).
For high heat transfer effectiveness, tubes for transporting the working fluid of the evaporator 3 and/or the condenser 5 has at least one aluminium section and at least one copper section or is entirely made of copper or is entirely made of aluminium. Preferably, an outer diameter of that tube is 5 mm. A tube thickness may then range between 0.2 and 0.25 mm.
To achieve a particularly compact design, a depth d of each of the heat exchangers 3, 5 along the process air channel 1 is smaller than 70 mm, e.g. approx. 65 mm. This may, e.g., be achieved by setting a number of rows of linear tube sections (pipes) along the process air channel 1 to four or less for the evaporator 3 as well as for the condenser 5.
The number of linear tube sections along a vertical direction may differ, e.g. being five for the evaporator 3 and seven for the condenser 5. This may translate to a vertical height of approx. 95 mm for the evaporator 3 and approx. 135 mm for the condenser 5.
A depth of the gap between the evaporator 3 and the condenser 5 may be in the range between 200 mm and 260 mm, in particular between 220 mm and 240 mm, especially around 230 mm.
Fig.4 shows a top-down view on a section of a process air channel 1 of a clothes drying appliance 8. The clothes drying appliance 8 is similar to the clothes drying appliance 1 with the difference that the compressor 4 is now transversely oriented with respect to the process air channel 1. Therefore, the longitudinal axis L of the compressor 4 and the flow direction of the process air 1 and the direction of the process air channel 1, respectively, are perpendicular in the top-down view. This orientation enables a particularly high energy transfer.
Of course, the invention is not restricted to the described embodiments.
For example, the clothes drying appliance may have an open-loop air channel or air conduit. In such case the compressor may be positioned after the condenser, that is, downstream with respect to a direction of a process air flow, or between the evaporator and the condenser. At any rate it is advantageous to have the compressor accommodated downstream of the evaporator, to heat up the process air before sending it back to the ambient wherefrom it had been taken.

Claims

A clothes drying appliance (2; 8), comprising a process air channel (1) and a heat pump (3, 4, 5), wherein
- an evaporator (3) and a condenser (5) of the heat pump (3, 4, 5) are accommodated within the process air channel (1), with the condenser (5) accommodated downstream of the evaporator (3) with respect to a direction of a process air flow, and wherein

- a compressor (4) of the heat pump (3-5) is accommodated within the process air channel (1) between the evaporator (3) and the condenser (5)
characterized in that
- the compressor (4) is a horizontal rotary compressor;

- the process air channel (1) comprises a linear tube-like enclosure housing the evaporator (3), the compressor (4), and the condenser (5);

- the evaporator (3) is realized as a first finned tube-type heat exchanger and the condenser (5) is realized as a second finned tube-type heat exchanger;

- a fin spacing of the condenser (5) is smaller than a fin spacing of the evaporator (3); and

- a number of rows of linear tube sections along the process air channel (1) is the same for the condenser (5) and the evaporator (3) while a number of linear tube sections along a vertical direction is greater for the condenser (5).
The clothes drying appliance (2; 8) according to claim 1, wherein a longitudinal axis (L) of the compressor (4) deviates not more than 5° from a horizontal plane (H).
The clothes drying appliance (2) according to claim 2, wherein a longitudinal axis of the compressor (4) and a flow direction of the process air channel (1) are within the same vertical plane.
The clothes drying appliance (8) according to claim 2, wherein the compressor (4) is transversely oriented with respect to the process air channel (1) such that a vertical plane comprising a longitudinal axis of the compressor (4) and a vertical plane comprising a flow direction of the process air are perpendicular to each other.
The clothes drying appliance (2; 8) according to any of the preceding claims, wherein the evaporator (3), the compressor (4) and the condenser (5) are components fixed at a base module of a plastic bottom group.
The clothes drying appliance (2; 8) according to any of the preceding claims, wherein the evaporator (3) and the condenser (5) are seated at the same height.
The clothes drying appliance (2; 8) according to any of the preceding claims,
wherein
- a tube of at least one of the heat exchangers (3, 5) has at least one aluminium section and at least one copper section or is entirely made of copper or entirely made of aluminium,

- an outer diameter of that tube is 5 mm or smaller, and

- a fin spacing of the least one of the heat exchangers is 2.5 mm or smaller.
The clothes drying appliance (2; 8) according to any of the preceding claims, wherein a depth (d) of each of the evaporator (3) and the condenser (5) along the process air channel is 70 mm or smaller.
The clothes drying appliance (2; 8) according to any of the preceding claims,
wherein
- the clothes drying appliance (2; 8) is a household appliance in which the process air channel (1) is part of a closed-loop process air circuit,

- the process air circuit also comprises a rotatable drum for holding clothes,

- an air outlet of the drum is connected to one end of the process air channel (1),

- another end of the process air channel (1) is connected to an air inlet of the drum, and

- the condenser (5) is positioned downstream of the evaporator (3).
A clothes drying appliance comprising a process air channel (1) and a heat pump (3, 4, 5), wherein
- an evaporator (3) and a condenser (5) of the heat pump (3, 4, 5) are accommodated within the process air channel (1),

- the clothes drying appliance is a household appliance in which the process air channel is part of an open-loop process air channel,

- the process air circuit also comprises a rotatable drum for holding clothes,

- an air inlet section of the process air channel is positioned between an air inlet opening of this section and an air inlet of the drum and comprises the condenser (5),

- an air outlet section of the process air channel is positioned between an air outlet of the drum and an air outlet opening of this section and comprises the evaporator (3),
characterized in that
- the compressor (4) is a horizontal rotary compressor;

- the process air channel (1) comprises a linear tube-like enclosure housing the evaporator (3), the compressor (4), and the condenser (5);

- the evaporator (3) is realized as a first finned tube-type heat exchanger and the condenser (5) is realized as a second finned tube-type heat exchanger;

- a fin spacing of the condenser (5) is smaller than a fin spacing of the evaporator (3);

- and a number of rows of linear tube sections along the process air channel (1) is the same for the condenser (5) and the evaporator (3) while a number of linear tube sections along a vertical direction is greater for the condenser (5),

- the compressor (4) is positioned either in the air inlet section between the condenser and the drum, or in the air inlet section between the air inlet opening and the condenser, or in the air outlet section between the evaporator and the air outlet opening.