U.S. patent application number 13/127997 was filed with the patent office on 2011-09-01 for condenser dryer having a heat pump, and method for operating the same.
This patent application is currently assigned to BSH BOSCH UND SIEMENS HAUSGERATE GMBH. Invention is credited to Uwe-Jens Krausch, Andreas Stolze.
Application Number | 20110209484 13/127997 |
Document ID | / |
Family ID | 41511088 |
Filed Date | 2011-09-01 |
United States Patent
Application |
20110209484 |
Kind Code |
A1 |
Krausch; Uwe-Jens ; et
al. |
September 1, 2011 |
CONDENSER DRYER HAVING A HEAT PUMP, AND METHOD FOR OPERATING THE
SAME
Abstract
A condenser dryer includes a drying chamber for items to be
dried; a process-air circuit including a fan; and a heat pump in
which a refrigerant circulates. The heat pump has an evaporator and
a condenser, with the evaporator or the condenser or both being a
heat exchanger having level surfaces and including at least one
endlessly folded, flattened tube to form a plurality of rows of
meander stacks in laterally offset relationship.
Inventors: |
Krausch; Uwe-Jens;
(Brieselang, DE) ; Stolze; Andreas; (Falkensee,
DE) |
Assignee: |
BSH BOSCH UND SIEMENS HAUSGERATE
GMBH
Munich
DE
|
Family ID: |
41511088 |
Appl. No.: |
13/127997 |
Filed: |
November 9, 2009 |
PCT Filed: |
November 9, 2009 |
PCT NO: |
PCT/EP09/64829 |
371 Date: |
May 6, 2011 |
Current U.S.
Class: |
62/79 ;
62/238.6 |
Current CPC
Class: |
D06F 58/206 20130101;
F28D 1/0426 20130101; F28D 1/0478 20130101; F28F 1/022
20130101 |
Class at
Publication: |
62/79 ;
62/238.6 |
International
Class: |
F25B 29/00 20060101
F25B029/00; F25B 27/00 20060101 F25B027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 20, 2008 |
DE |
10 2008 043 920.7 |
Claims
1-13. (canceled)
14. A condenser dryer, comprising: a drying chamber for items to be
dried; a process-air circuit including a fan; and a heat pump in
which a refrigerant circulates, said heat pump having an evaporator
and a condenser, said evaporator or said condenser, or both, being
a heat exchanger having level surfaces and including at least one
endlessly folded, flattened tube to form a plurality of rows of
meander stacks in laterally offset relationship.
15. The condenser dryer of claim 14, wherein said flattened tube
has at least two hollow chambers extending in a longitudinal
direction of the tube.
16. The condenser dryer of claim 15, wherein the flattened tube has
three to eight hollow chambers extending in a longitudinal
direction of the tube.
17. The condenser dryer of claim 14, wherein the flattened tube is
defined by a ratio between a width and height in a range of 4 to
25.
18. The condenser dryer of claim 14, wherein one of the evaporator
or condenser, or both, includes at least two endlessly folded,
flattened tubes, each tube forming a plurality of rows of mutually
laterally offset meander stacks.
19. The condenser dryer of claim 18, wherein each plurality of rows
of mutually laterally offset meander stacks of the at least two
endlessly folded, flattened tubes have been pushed one into another
of said pluralities.
20. The condenser dryer of claim 18, wherein at least two endlessly
folded, flattened tubes are connected in parallel.
21. The condenser dryer of claim 18, wherein at least two endlessly
folded, flattened tubes are connected in series.
22. The condenser dryer of claim 18, wherein the at least one
endlessly folded, flattened tube has a flat surface.
23. The condenser dryer of claim 18, wherein the endlessly folded,
flattened tube is located completely in the process-air
circuit.
24. The condenser dryer of claim 18, wherein the flattened tube is
made of copper or aluminum.
25. The condenser dryer of claim 18, wherein the flattened tube has
straight sections and curved sections in at least one meander
stack, said straight sections extending in parallel relationship at
a distance, with a ratio of the distance between the straight
sections and a height of the tube being defined by a range from 1.5
to 10.
26. A method for operating a condenser dryer having a drying
chamber for items requiring to be dried, a process-air circuit, a
fan in the process-air circuit, and a heat pump in which a
refrigerant circulates, the heat pump having an evaporator, a
compressor, a throttle, and a condenser, the evaporator and/or
condenser being a heat exchanger, said method comprising the steps
of: providing level surfaces on the heat exchanger and at least one
endlessly folded, flattened tube that forms a plurality of rows of
meander stacks in laterally offset relationship; ducting a
refrigerant through the flattened tube; and ducting the process air
over the flattened tube so as to cause an exchange of heat between
the refrigerant and the process air.
27. The method of claim 26, wherein a turbulent flow of refrigerant
is provided in the step of ducting refrigerant through the
flattened tube.
28. The method of claim 26, wherein the refrigerant is ducted by a
cross-flow method, relative to the process air.
29. The method of claim 26, wherein a turbulent flow of refrigerant
is ducted by a counter-current method, relative to the process
air.
30. The method of claim 26, wherein the condenser dryer also has an
air-to-air heat exchanger, said method further comprising the step
of coordinating the control of the heat pump with the control of
the air-to-air heat exchanger so as to keep the temperature of the
refrigerant in the heat pump within a predetermined range.
31. The method of claim 30, wherein the step of coordinating
control of the heat pump with the control of the air-to-air heat
exchanger lessens the heating power of the air-to-air heat
exchanger as the degree of dryness of the items requiring to be
dried in the condenser dryer advances.
32. The method of claim 30, wherein the step of coordinating
control of the heat pump with the control of the air-to-air heat
exchanger increases the cooling power of the heat pump as the
degree of dryness of the items requiring to be dried in the
condenser dryer advances.
Description
[0001] The invention relates to a condenser dryer having a heat
pump that includes a special evaporator and/or condenser and to a
preferred method for operating the dryer.
[0002] In a condenser dryer, air (what is termed process air) is
ducted by a fan over a heater into a drum containing damp laundry
items and serving as a drying chamber. The hot air absorbs moisture
from the laundry items requiring to be dried. Having passed through
the drum the then moist process air is ducted into a heat exchanger
in front of which a lint filter is as a rule connected.
[0003] That drying process is energy-intensive because when the
process air is cooled in the heat exchanger the heat in the current
of process air is in energy terms lost to the process with the
heated current of cooling air. That energy loss can be
significantly reduced by employing a heat pump. In a condenser
dryer fitted with a heat pump the warm, moisture-laden process air
is cooled substantially in the evaporator of the heat pump, where
the transferred heat is used for evaporating a refrigerant
circulating in the heat pump. The refrigerant that is evaporated
through being heated is fed via a compressor to the heat pump's
condenser where, owing to the gaseous refrigerant's being
condensed, heat is released that is used for heating the process
air before it enters the drum. The water contained in the moist
process air condenses in the evaporator. The condensed water is
then generally collected in a suitable container and the cooled and
dried process air fed back to the heater and then to the drum.
[0004] Described in DE 40 23 000 C2 is a laundry dryer that has a
heat pump and in which an air-intake opening that can be sealed by
means of a controllable sealing device is located in the
process-air channel between the heat source and heat sink.
[0005] Proceeding from both WO 2008/107266 A1 and WO 2008/119611 A1
is a laundry dryer having a heat pump. A heat pump in a laundry
dryer is as a rule embodied as a compact unit and located beneath
the drum for the laundry items requiring to be dried. There is no
electric heater for the process air.
[0006] DE 20 2006 014 718 U1 relates to a laundry drier that has a
heat pump that uses CO.sub.2 as the medium and in which a heat
exchanger is employed that has a plurality of heat-exchanging
bodies and at least one tube--arranged to be in thermal contact
with said bodies--for the medium, with a thermal conduction inside
each heat-exchanging body being greater than a thermal conduction
between the heat-exchanging bodies. Sections assigned to different
temperature ranges of the tube are therein in contact with
different heat-exchanging bodies in such a way that each
heat-exchanging body is assigned to only one temperature range of
the tube. The heat-exchanging bodies are formed in particular by
plates, with the edges of the plates of adjacent heat-exchanging
bodies being separated by a gap by means of which a thermal
separation is realized. Differently sized heat-exchanging bodies
are joined to the meandering tube, with its also being possible for
the loop density of the meandering tube to change along the heat
exchanger's length.
[0007] WO 06/101565 A1 relates to a heat-exchanger arrangement, in
particular a cooling system, that includes a compressor for
conveying a coolant along a flow path in at least one system
operating mode and a first and second heat exchanger, with at least
one of said heat exchangers including a flat-tube heat exchanger.
The flat-tube heat exchanger has a serpentine configuration
defining a plurality of substantially parallel flow paths. The heat
exchanger can include a plurality of rows of serpentine windings in
the case of which the spacing between the rows (known as the row
pitch) can be changed. The invention ought to be advantageous
especially for compact commercial cooling systems such as, for
instance, bottle coolers.
[0008] US 2007/0084590 A1 relates to a heat exchanger for
exchanging heat between a first fluid and a second fluid, in
particular a heat exchanger for motor vehicles for exchanging heat
between water and a coolant. The heat exchanger includes a first
flow path unit for a first fluid, which unit contains at least two
return flow paths that are mutually opposed, and a second flow path
unit having second flow paths in which a second fluid flows
perpendicularly to the first fluid. The first flow path unit's flow
paths are shaped as, for example, meandering and embodied as flat
tubes. The second flow paths contain a U-shaped flow path. The heat
exchanger thus consists of two flow path units that are arranged in
a complex manner with respect to each other.
[0009] Every heat pump hitherto employed in a condenser dryer has
heat exchangers (evaporators, condensers) that are relatively large
and tend, moreover, to become soiled by lint particles carried on
the process air so that the need for cleaning and maintenance is
substantial. That problem along with ways and means for resolving
it are presented in documents WO 2008/107266 A1 and WO 2008/119611
A1. The problem has been a pronounced one to date in particular
because the tubes employed in the heat exchangers used hitherto
have lamellas for efficient heat exchanging, meaning they do not
have level surfaces. The air resistance is moreover high in a
design of such kind and hence the process air's flow is not
optimal.
[0010] The object of the invention was therefore to provide a
condenser dryer having a heat pump and further to provide a method
for operating the dryer by means of which dryer and method the
above problems will be obviated. That is to be achieved in
particular using a compact and low-maintenance heat exchanger.
[0011] Said object is inventively achieved by means of a condenser
dryer having the features of the corresponding independent claims
and by means of the method set out in the corresponding independent
claim. Preferred embodiments of the inventive condenser dryer are
listed in corresponding dependent claims. Preferred embodiments of
the inventive method correspond to preferred embodiments of the
inventive condenser dryer even if that is not explicitly
established herein.
[0012] The subject matter of the invention is hence a condenser
dryer having a drying chamber for the items requiring to be dried,
a process-air circuit, a fan in the process-air circuit, and a heat
pump, in which a refrigerant circulates, having an evaporator, a
compressor, a throttle, and a condenser, with the evaporator and/or
condenser being a heat exchanger having level surfaces and
including at least one endlessly folded, flattened tube that forms
a plurality of rows of mutually laterally offset meander
stacks.
[0013] The term "endlessly folded, flattened tube" is also
abbreviated below to "flattened tube".
[0014] "Endlessly folded" within the meaning of the invention means
there are no connections, by way of braces, for example, between
individual sections of the flattened tube.
[0015] "A plurality of rows of mutually laterally offset meander
stacks" means there are at least two meander stacks in the heat
exchanger that are mutually laterally offset, with their being
"laterally offset" resulting preferably in meander stacks that are
arranged substantially mutually parallel. There are preferably 3 to
30 meander stacks and particularly preferably 5 to 20 meander
stacks.
[0016] "Level surface" means that the heat exchanger has no
lamellas or ribs through which the tube would extend and which
would serve to enlarge the heat exchanger's surface available for
heat exchanging. The surface necessary for effective heat
exchanging is inventively achieved by flattening and multiply
folding the tube used in the heat exchanger.
[0017] The flattened tube's width b and height h.sub.T otherwise
remaining the same, its length will generally depend on the
evaporator's and/or condenser's desired heat-exchanging capacity.
Because the transfer of heat is significantly better in the case of
moist air, the flattened tube's length when the heat exchanger is
used as a condenser is therein preferably 1.5 to 3 times longer
than when the heat exchanger is used as an evaporator. If in an
embodiment of the invention the flattened tube is used both in the
evaporator and in the condenser and the heights h.sub.T and widths
b of the flattened tubes respectively employed in the condenser and
evaporator are different, the respective tube lengths in the
condenser and evaporator will preferably be set such as to produce
a value of 1.5 to 3 for the ratio between an overall tube surface
A.sub.T.sup.C in the condenser and an overall tube surface
A.sub.T.sup.E in the evaporator.
[0018] In a preferred embodiment of the invention the flattened
tube has at least two hollow chambers extending in a longitudinal
direction of the tube. The heat pump's refrigerant is generally
located in the hollow chambers. The flattened tube has preferably
three to eight hollow chambers extending in a longitudinal
direction of the tube.
[0019] "Flattened tube" within the meaning of the invention
includes any tube whose height h.sub.T is less than its width b.
Tubes of such kind can be produced by, for example, in a manner
known per se to a person skilled in the relevant art deforming a
tube originally having a circular cross-section.
[0020] Preferably the ratio b/h.sub.T between a width b and height
h.sub.T of the flattened tube is in the 4-to-25 range, preferably
in the 7-to-20 range, and quite particularly preferably in the
8-to-15 range.
[0021] Used in a preferred embodiment are flattened tubes having a
height h.sub.T in the 1-to-5-mm range, preferably 1.5 to 3 mm, and
a width b in the 10-to-50-mm range, preferably 15 to 30 mm.
[0022] In another preferred embodiment of the invention the
evaporator and/or condenser include(s) at least two endlessly
folded, flattened tubes each forming a plurality of rows of
mutually laterally offset meander stacks. The respective plurality
of rows of mutually laterally offset meander stacks of the at least
two endlessly folded, flattened tubes have therein preferably been
pushed one into the other.
[0023] In the inventively employed heat exchanger the first and,
where applicable, further flattened tubes are generally suitably
embodied at their ends so that when used as an evaporator and/or
condenser they can be built into a heat pump.
[0024] When at least two endlessly folded, flattened tubes are used
they can be connected in parallel or in series. When said tubes are
connected in series, a refrigerant used in the heat pump initially
flows through a first flattened tube and then through a second and,
where applicable, further flattened tube(s). When said tubes are
connected in parallel, a flow of refrigerant is by contrast divided
into a plurality of partial flows. Said partial flows will then be
ducted through the at least two endlessly folded, flattened tubes
simultaneously.
[0025] In the inventive condenser dryer it is preferred for the at
least two endlessly folded, flattened tubes to be connected in
parallel. Possible losses of pressure can be advantageously reduced
thereby.
[0026] In a particularly preferred embodiment of the inventive
condenser dryer the at least one endlessly folded, flattened tube
has a level surface.
[0027] It is furthermore preferred for the endlessly folded,
flattened tube to be located completely in the process-air circuit.
That will be advantageous particularly when the at least one
endlessly folded, flattened tube has a flat surface. "Flat" here
means that the surface does not contain any substantial structures
of the nature of ribs, naps, lamellas, and suchlike. It is
inventively possible to achieve the desired properties in terms of
heat exchanging solely through the tube's having been flattened and
multiply folded without having to use any additional components
such as ribs, lamellas, and suchlike. The heat exchanger will
thereby be given a particularly level surface that will in any
event not favor the deposition of dirt such as lint particles and
moreover be very easy to clean. Said surface can for that purpose
possibly also have been provided with a dirt-repellant coating.
[0028] The flattened tube is made preferably of copper or aluminum,
particularly preferably of aluminum.
[0029] In a preferred embodiment the flattened tube has straight
sections and curved sections in at least one meander stack, with
the straight sections being mutually parallel and a distance
d.sub.A between the straight sections and a height h.sub.T of the
flattened tube forming a d.sub.A/h.sub.T ratio that is preferably
in the 1.5-to-10 range and particularly preferably the 2-to-7
range.
[0030] The distance d.sub.A is preferably 3 to 10 mm and more
preferably 5 to 8 mm; with a height h.sub.T in the 1-to-5-mm range,
preferably the 1.5-to-3-mm range, and a width b in the 10-to-50-mm
range, preferably the 15-to-30-mm range.
[0031] Owing to the endless folding and the formation of mutually
laterally offset meander stacks, the flattened tube employed in the
inventive condenser dryer preferably forms approximately a cuboid
having a height h.sub.s, a width b.sub.M, and a depth d.sub.M. The
height h.sub.s is preferably in the 80-to-250-mm range and more
preferably the 100-to-200-mm range. The width b.sub.M is preferably
in the 50-to-200-mm range and more preferably the 80-to-150-mm
range. The depth d.sub.M is preferably in the 120-to-300-mm range
and more preferably the 150-to-250-mm range.
[0032] The inventive condenser dryer can be embodied as an
exhaust-air dryer or a circulating-air dryer.
[0033] The process air can be heated exclusively via the heat
pump's condenser. An electric heater can, though, be employed
additionally in the inventive condenser dryer. In a preferred
embodiment of the invention the heat pump's condenser is the only
heater for the process air. The condenser is therein arranged
preferably in the process-air circuit between the fan and an outlet
of the drying chamber.
[0034] The inventive condenser dryer preferably has an acoustic
and/or optical display means for displaying one or more operating
statuses. An optical display means can be, for example, a
liquid-crystal display on which specific requests or advisories are
indicated. It is additionally or alternatively possible for
light-emitting diodes to light up in one or more colors.
[0035] To better control the heat-exchanging processes in the
condenser dryer the inventive condenser dryer can additionally
include an air-to-air heat exchanger embodied preferably as
detach-able. That will be especially advantageous because a
detachable heat exchanger can be more easily cleaned of lint
particles.
[0036] The refrigerant employed in the heat pump has preferably
been selected from the group that includes propane, carbon dioxide,
fluorohydrocarbon compounds, and mixtures of such, in particular
the fluorohydrocarbon compounds R134a and R152a and the mixtures
R407C and R410A.
[0037] How the hollow chambers are embodied will generally depend
on what refrigerant has been selected. In particular the size of
the hollow chambers, the distance of the hollow chambers from the
tube surface, and the distance between the hollow chambers
themselves will depend on the refrigerant. Small distances or, as
the case may be, thin walls are possible in the case of
refrigerants having a relatively low vapor pressure so that the
portion of the hollow chambers' cross-section referred to the
flattened tube's overall cross-section can be large.
[0038] Alongside an evaporator, a condenser, and a compressor, the
heat pump in the inventive condenser dryer has in the refrigerant's
direction of flow between the condenser and evaporator a throttle,
in particular an expansion valve, a restrictor, or a capillary.
[0039] The refrigerant employed in the heat pump circulates
preferably with a turbulent flow. A turbulent flow can be set by
means of a structurally suitably embodied flow channel and/or by
means of suitable drive means (for example a compressor).
[0040] The temperature of the heat pump's refrigerant, in
particular in the condenser, is kept within the permissible range
generally via the heat pump's controller and, where applicable, an
additional air-to-air heat exchanger. If there is an additional
heater for the condenser dryer in the process-air circuit,
controlling of the heat pump will preferably be coordinated with
that of the heater.
[0041] It is inventively preferred for process air and cooling air
or, as the case may be, process air and refrigerant in the heat
pump to be ducted in each case by a cross-flow or, as the case may
be, counter-current method through the corresponding heat
exchangers.
[0042] If alongside the heat pump another heater is employed in the
inventive condenser dryer, said heater will preferably be a
two-stage heater. Because the energy needed for drying decreases
with the advancing degree of dryness of the items requiring to be
dried in the condenser dryer, it is expedient to regulate the
heater accordingly, meaning to lessen its heating power as the
degree of dryness advances in order to maintain an equilibrium
between the drying energy supplied and that which is necessary.
[0043] A lesser heating power or even an increasing cooling power
of the heat pump will hence be necessary with the advancing degree
of dryness of the items requiring to be dried, laundry in
particular. Particularly the temperature in the process-air circuit
would rise sharply after a concluded drying phase. The heat pump
and, where applicable, an additional heater in the condenser dryer
will therefore generally be regulated such that a maximum
permissible temperature will not be exceeded in the drying
chamber.
[0044] Temperature sensors known per se to a person skilled in the
relevant art are generally employed in the heat pump and/or
process-air circuit for monitoring the temperature of the
refrigerant or as the case may be, heat pump and, where applicable,
the temperature of the process air.
[0045] The invention relates also to a method for operating a
condenser dryer having a drying chamber for the items requiring to
be dried, a process-air circuit, a fan in the process-air circuit,
and a heat pump, in which a refrigerant circulates, having an
evaporator, a compressor, a throttle, and a condenser, with the
evaporator and/or condenser being a heat exchanger having level
surfaces and including at least one endlessly folded, flattened
tube that forms a plurality of rows of mutually laterally offset
meander stacks, with a refrigerant being ducted through the
flattened tube and causing an exchange of heat with a process
air.
[0046] The invention has the advantage that compact and
easy-to-maintain heat exchangers capable, moreover, of being
produced economically can be used as evaporators and/or condensers
in the condenser dryer. The flow of the process air through the
heat pump's heat exchanger(s) is furthermore improved in the
inventive condenser dryer. The heat exchanger employed in the
inventive condenser dryer has a low flow resistance. Unlike a
conventional condenser dryer, the inventive condenser dryer has a
heat exchanger even around whose curved region process air can flow
with no loss of performance. The result is a condenser dryer having
improved heat-exchanging efficiency.
[0047] Further details of the invention will emerge from the
following description of non-limiting exemplary embodiments of the
inventive condenser dryer and of a method employing said condenser
dryer. Reference is therein made to FIGS. 1 to 4.
[0048] FIG. 1 shows a vertical section through a condenser dryer
fitted with a heat pump.
[0049] FIG. 2 shows a first embodiment of a heat exchanger employed
in the condenser dryer and having a single endlessly folded,
flattened tube. FIG. 2a) is a perspective view and FIG. 2b) a
lateral view.
[0050] FIG. 3 shows a second embodiment of a heat exchanger
employed in the condenser dryer and having two endlessly folded,
flattened tubes. FIG. 3a) is a perspective view and FIG. 3b) a
lateral view.
[0051] FIG. 4 shows a cross-section through a flattened tube
employed in an embodiment of the condenser dryer.
[0052] FIG. 1 shows a vertical section through a condenser dryer 1
(abbreviated below to "dryer" 1) fitted with a heat pump. Dryer 1
has a drum 3, which can be turned around a horizontal axis, serving
as a drying chamber 3 secured inside which are agitators 4 for
moving laundry while the drum is turning. Process air is ducted by
means of a fan 19 though a drum 3 and a heat pump 13, 14, 15, 17 in
an air channel 2 in a closed circuit (process-air circuit 2). The
moist, warm process air is cooled after passing through drum 3 then
heated up again when the moisture contained in the process air has
condensed. Heated air is therein ducted from behind, meaning from
the side of drum 3 opposite a door 5, though a perforated base into
drum 3, makes contact there with the laundry requiring to be dried,
and flows through the loading opening of drum 3 to a lint filter 6
inside a door 5 that seals the loading opening. The air current is
then redirected downward in door 5 and ducted in air channel 2 via
an outlet 26 to evaporator 13 of heat pump 13, 14, 15, 17 where it
is cooled. The heat pump's refrigerant therein evaporated in
evaporator 13 is ducted via a compressor 14 to condenser 15. The
refrigerant condenses in condenser 15, therein giving off heat to
the process air. The refrigerant now existing in liquid form is
then ducted back to evaporator 13 via a throttle 17, as a result of
which the refrigerant circuit will have been closed. Below
evaporator 13 is a condensate tray 23 in which the condensate
produced as the moist, warm process air cools is collected. The
condensate can be safely removed through mechanical emptying, for
example, or by being pumped out of condensate tray 23.
[0053] Both evaporator 13 and condenser 15 have an endlessly
folded, smooth, flattened tube not shown in further detail in FIG.
1.
[0054] In the embodiment shown in FIG. 1, drum 3 is supported on
the rear base by means of a pivot bearing and at the front by means
of an end shield 7, with drum 3 resting with a flange on a glide
strip 8 on end shield 7 and being thus retained on the front end.
The condenser dryer 1 is controlled via a controller 10 that can be
regulated by the user via a control unit 9. Different statuses of
condenser dryer 1 can be optically or acoustically indicated by
means of a display device 18.
[0055] Dryer 1 shown in FIG. 1 has an electric supplementary heater
27.
[0056] FIG. 2 shows a first embodiment of a heat exchanger that is
employed in condenser dryer 1 and has level surfaces and a single
endlessly folded, flattened tube 16 forming eleven laterally offset
meander stacks 20. FIG. 2a) is a perspective view and FIG. 2b) a
lateral view. 10 signifies a straight section of flattened tube 16
and 11 a curved section of flattened tube 16. d.sub.M is the depth,
h.sub.S is the height, and b.sub.M is the width of the heat
exchanger. d.sub.A is a distance between two straight sections 10.
28 signifies terminals for feeding a refrigerant in and out.
[0057] FIG. 3 shows a second embodiment of a heat exchanger that is
employed in condenser dryer 1 and has level surfaces and two
endlessly folded, flattened tubes 16 and 25. Flattened tube 16
forms five meander stacks 20 and flattened tube 25 forms five
meander stacks 22. FIG. 3a) is a perspective view and FIG. 3b) a
lateral view. 10 signifies a straight section of flattened tubes 16
and 25 and 11 a curved section of flattened tubes 16 and 25.
d.sub.A is a distance between two straight sections 10. 28
signifies terminals for feeding a refrigerant in and out. The open
arrows indicate the direction in which the refrigerant flows in
flattened tubes 16 and 25.
[0058] FIG. 4 shows a cross-section through a flattened tube 16
used in an embodiment of condenser dryer 1. Five hollow chambers 21
extend in a longitudinal direction of flattened tube 16 in the
embodiment shown here. Flattened tube 16 has a height h.sub.T and a
width b.
[0059] The refrigerant is ducted through flattened tube 16 and an
exchange of heat with the process air effected when said condenser
dryer 1 in which evaporator 13 and/or condenser 15 is a heat
exchanger 13, 15 having level surfaces and including at least one
endlessly folded, flattened tube 16 that forms a plurality of rows
of mutually laterally offset meander stacks 20 is operating.
[0060] Compact and easy-to-maintain heat exchangers 13, 15 that
have level surfaces and are capable, moreover, of being produced
economically are hence employed in condenser dryer 1. The flow of
the process air through heat exchanger(s) 13, 15 of heat pump 13,
14, 15, 17 is furthermore improved because a heat exchanger 13, 15
of such kind has a low flow resistance. Process air can flow around
heat exchanger 13, 15 even in the curved region of flattened tube
16 with no loss of performance. The result is a condenser dryer 1
having improved heat-exchanging efficiency.
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