U.S. patent application number 17/173349 was filed with the patent office on 2022-08-11 for heat exchanger.
The applicant listed for this patent is MAHLE International GmbH. Invention is credited to Scott Kent, Robert Louis Runk.
Application Number | 20220252349 17/173349 |
Document ID | / |
Family ID | 1000005519446 |
Filed Date | 2022-08-11 |
United States Patent
Application |
20220252349 |
Kind Code |
A1 |
Runk; Robert Louis ; et
al. |
August 11, 2022 |
HEAT EXCHANGER
Abstract
A heat exchanger (1) for a motor vehicle (2), has first flat
tubes (3) with a first longitudinal end (4) received in associated
first openings (5) of a first collector (6) and with an opposite
second longitudinal end (7) in associated second openings (8) of a
second collector (9). Second flat tubes (10) have a first
longitudinal end (11) received in associated third openings (12) of
a third collector (13) and a second longitudinal end (15) in
associated fourth openings (16) of the second collector (9). Only
the first flat tubes (3) or both the first and second flat tubes
(3, 10) have an angled end region (14). The second and fourth
openings (8, 16) are arranged spaced apart from one another with
heat transfer fins (18) in between.
Inventors: |
Runk; Robert Louis;
(Lockport, NY) ; Kent; Scott; (Albion,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAHLE International GmbH |
Stuttgart |
|
DE |
|
|
Family ID: |
1000005519446 |
Appl. No.: |
17/173349 |
Filed: |
February 11, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28D 1/0471 20130101;
F28D 1/05358 20130101; F28F 2009/0297 20130101; F28F 9/0243
20130101 |
International
Class: |
F28D 1/053 20060101
F28D001/053; F28D 1/047 20060101 F28D001/047; F28F 9/02 20060101
F28F009/02 |
Claims
1. A heat exchanger (1) comprising: first flat tubes (3) having a
first longitudinal end (4) received in associated first openings
(5) of a first collector (6) and an opposite second longitudinal
end (7) in associated second openings (8) of a second collector
(9), second flat tubes (10) having a first longitudinal end (11)
received in associated third openings (12) of a third collector
(13), wherein only the first flat tubes (3) or both the first flat
tubes (3,) and the second flat tubes (10) have a bent or angled end
region (14), wherein the second flat tubes (10) have a second
longitudinal end (15) opposite the first longitudinal end (11)
received in associated fourth openings (16) of the second collector
(9), and wherein the second and fourth openings (8, 16) are
arranged spaced apart from one another with heat transfer fins (18)
in-between.
2. The heat exchanger according to claim 1, wherein the first flat
tubes (3) and second flat tubes (10) are arranged alternating.
3. The heat exchanger according to claim 1, wherein a height
(H.sub.1) of the bent or angled end region (14) of the first flat
tubes (3) or of both flat tubes (3, 10) maximally amounts to half
of a total height (H) of the first flat tubes (3) or of both flat
tubes (3, 10).
4. The heat exchanger according to claim 1, wherein a height
(H.sub.1) of the bent or angled end region (14) of the first flat
tubes (3) or of both flat tubes (3, 10) maximally amounts to 20% of
a total height (H) of the first flat tubes (3) or of both flat
tubes (3, 10).
5. The heat exchanger according to claim 1, wherein at least one of
the first collector (6), the second collector (9) and the third
collector (13) has a circular cross section.
6. The heat exchanger according to claim 1, wherein at least one of
the first collector (6), the second collector (9), the third
collector (13), the first flat tubes (3), or the second flat tubes
(10) is formed from aluminium.
7. The heat exchanger according to claim 1, wherein the first
collector (6) is arranged closer to the second collector (9) than
to the third collector (13).
8. The heat exchanger according to claim 1, wherein the second
collector (9) is arranged closer to the first collector (6) than to
the third collector (13).
9. A thermal circuit (20), forming a coolant circuit or a
refrigerant circuit of an air conditioning or refrigeration system
for a refrigerated trailer of a motor vehicle (2), the thermal
circuit comprising the heat exchanger (1) according to claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat exchanger and to a
thermal circuit having at least one such heat exchanger.
BACKGROUND
[0002] In heat pump applications and heat exchangers having merely
a single passage there is a problem in unfavourable outside
conditions that the same freeze up easily. This situation can be
solved by increasing the pressure at the inlet of the refrigerant
tubes (after any expansion device). Higher pressure equates to a
higher saturation temperature which is the mechanism which helps
delay frost formation. Simply increasing the inlet pressure is not
easily accomplished as the desirable outlet pressure is a fixed
value and any changes, which increase the refrigerant pressure
drop, without improving the heat transfer coefficient have a
negative impact on capacity. Since the outlet is a fixed value and
the increase in pressure at the inlet needs to occur after any
expansion apparatus (including the distributor) the increase in
pressure must come from something in the core block itself to
minimize performance loss. Adding pressure drop within the exit
manifold through a device commonly referred to as a "gas collector"
reduces performance by about 3-4% per degree of saturation
temperature loss which comes with the pressure loss. Accomplishing
the slightly higher refrigerant pressure drop within the core tubes
themselves allows the possibility of the potential loss to be
recovered. This can be achieved for example through a meander-like
or multi-loop flow through the heat exchanger.
[0003] From EP 1 710 525 A1 a generic heat exchanger for a motor
vehicle having two flat tubes and altogether three collectors is
known, wherein a flow takes place from a first collector via a
first flat tube into a return distributor and from the latter via a
second flat tube into the second collector. At their longitudinal
ends, the flat tubes are twisted by 90.degree.. In the direction of
an air through-flow, the individual flat tubes or in each case a
pair of flat tubes are arranged one after the other, which causes
an increased air pressure drop during the flow.
[0004] From EP 1 762 808 A1 a further generic heat exchanger is
known, having a first collector via which fluid can be conducted in
first flat tubes to an opposite return distributor and from there
back via second flat tubes into a second collector. There, the two
collectors are arranged one after the other in the direction of an
air flow. The individual flat tubes are bent, wherein two flat
tubes each are incorporated in a common opening in the return
distributor. However, a heat transfer cannot be configured
optimally. In addition, the individual flat tubes are arranged,
seen in the direction of an air flow, one after the other at least
in regions, as a result of which an air pressure drop when flowing
through the heat exchanger is increased.
[0005] From CN 103 644 685 A a further heat exchanger having two
inflow collectors and two outflow collectors is known. However,
this creates a comparatively expensive and complex construction. In
addition, no mixing of a refrigerant takes place here since the
known solution shows merely two heat exchanger circuits in a common
heat exchanger area.
[0006] From US 2018/0340746 A a heat exchanger having a first
distributor and a second distributor is known, which are arranged
on the same side of the heat exchanger and comprises a multiplicity
of flat heat exchanger tubes. Accordingly, the heat exchanger tubes
run substantially U-shaped. A mixing of a refrigerant does not take
place there.
[0007] From CN 109 595 951 A a heat transfer with two inlet
collectors and two outlet collectors is likewise known, wherein
between an inlet collector and an outlet collector flat tubes are
arranged in each case and all flat tubes run in a plane at least in
regions. In addition, no mixing of a refrigerant takes place here
since the known solution shows merely two heat exchanger circuits
in a common heat exchanger area.
[0008] From US 2019/0049194 A a heat exchanger likewise having two
inlet collectors and two outlet collectors is known, wherein
between an inlet collector and an outlet collector flat tubes are
arranged in each case. There, the flat tubes are tapered at a
longitudinal end, i.e. they have an inlet or outlet merely on a
part surface on an end face, in order to be thereby inserted into
the respective associated inlet collector or outlet collector. In
the middle region of a heat exchanger block, these expand and are
consequently arranged in flow direction of the air parallel to one
another. However, basically two circuits that are separated from
one another are also present here.
[0009] Generally there is the problem with heat exchangers known
from the prior art of not having a solution to having a single
fluid circuit with high pressure drop that allows for
re-distribution or inter-mixing of the refrigerant within the heat
exchanger circuit while also not greatly increasing the air
pressure drop of the heat exchanger.
SUMMARY
[0010] The preferred embodiment of the present disclosure therefore
deals with the problem of presenting an improved or at least an
alternative embodiment for a heat exchanger of the generic type
which overcomes in particular the disadvantages known from the
prior art.
[0011] The present invention is based on the general idea of
increasing an internal fluid pressure drop in a heat exchanger, in
particular in a heat exchanger operated by means of refrigerant,
without at the same time increasing a pressure drop of an air flow
and thereby achieve a pressure drop within the heat exchanger with
the heat exchanger output remaining the same or under certain
conditions even increasing. The heat exchanger according to the
invention possesses first flat tubes which with a first
longitudinal end are received in associated first openings of a
first collector and with an opposite second longitudinal end in
associated second openings of a second collector. Additionally
provided are second flat tubes which with a first longitudinal end
are received in associated third openings of a third collector and
with an opposite second longitudinal end in associated fourth
openings of a second collector. In the second collector the second
and fourth openings have the same geometry and are arranged spaced
apart from one another at the same time, so that each flat tube
with a respective longitudinal end is received in a single opening
that is separate from other openings.
[0012] The second and fourth openings of the second collector
alternate such that the first and second tubes alternate at the
same time. According to the invention, only the first flat tubes or
both flat tubes have an angled or bent end region in order to be
received by the first collector or by the first and third
collectors. By way of the so-called U-flow of a fluid within the
heat exchanger, an increased pressure drop compared with a heat
exchanger that merely has to be flowed through once can thus be
achieved, wherein through the flat tubes that are spaced apart from
one another using heat exchange fins used to exchange heat with the
passing air, at the same time substantially lie in one plane so an
easily passable air flow can be ensured, as a result of which a
high heat exchanger output and at the same time a low pressure drop
of the air flowing through the heat exchanger can be brought about.
The second collector, for example a return distributor, receives
the first and second flat tubes alternating with a standard
distance between the individual flat tubes, while the first and
third collector, for example an inlet distributor and an outlet
distributor, merely have half the openings which additionally are
arranged with twice the standard distance from one another. The
inflow and the return flow into or out of the heat exchanger are
thus located on a side while on the opposite side merely the second
collector, i.e. the return distributor, is arranged. Basically, the
same can be arranged at the top or bottom. With the heat exchanger
according to an embodiment of the invention a high heat exchanger
output with low air pressure drop of the air flowing through the
heat exchanger and at the same time increased pressure drop for
example of a refrigerant in the heat exchanger is thus possible
through the U-flow. By way of this, the heat exchanger output can
thus be at least maintained preferentially even increased and at
the same time a frost risk lowered. In addition, an even
distribution of the fluid in the heat exchanger can be achieved
with the heat exchanger according to the invention since the
individual flat tubes are preferentially arranged alternating and
at the same time a mixing of the fluid flowing in the heat
exchanger, for example a refrigerant, takes place in the second
collector, i.e. the return distributor. Through the alternating
arrangement of the individual flat tubes a defrosting capacity can
also be increased and thereby a defrosting cycle shortened and the
overall energy efficiency of the heat exchanger increased.
[0013] The angled, bent or folded region is angled, bent or folded
such that the first collector or the first and third collector can
be positioned in the direction of airflow, outside or adjacent to
the plane of the coil, as a result of which an arrangement of the
first and third collector for example next to one another is
possible. Altogether, a heat exchanger block can be created with
such an arrangement which over a large part of its height only has
one plane and is therefore a comparatively flat construction.
[0014] In an advantageous further development of the solution
according to the invention, the first flat tubes are formed not
straight and the second flat tubes are formed angled, bent or
folded. In particular a second embodiment offers the major
advantage that the individual flat tubes can be formed identically
which lowers the production costs and have to be installed in the
heat exchanger according to the invention merely turned by
180.degree.. In this case, the first collector and the third
collector are situated one behind the other seen in the flow
direction of the air.
[0015] Practically, a height H.sub.1 of the angled, bent or folded
region of the first flat tubes maximally amounts to half of a
height H of the first flat tubes, preferentially even maximally 20%
of the total height H of the first flat tubes. The lower the height
H.sub.1 of the bent or angled region of the flat tubes is, the
greater is a parallel arrangement of the first and second flat
tubes in a common plane, as a result of which a heat exchanger of a
comparatively flat construction can be achieved.
[0016] Practically, the first collector, the second collector
and/or the third collector have a circular cross section. Through
the circular design, a flow-optimized shape in particular without
corners and edges can be created. The circular cross section is
also a pressure optimized shape in particular having resistance to
high internal pressure.
[0017] In a further advantageous embodiment of the solution
according to the invention, at least one of the collectors and/or
the first and/or second flat tubes and/or the heat transfer fins
between the tubes is/are formed from aluminium. Aluminium has a
comparatively high heat conduction coefficient, as a result of
which a high heat transfer rate is achievable. In addition,
aluminium is light which is advantageous in particular when the
heat exchanger according to the invention is employed in an on-road
or over the road application.
[0018] In a further advantageous embodiment of the solution
according to the invention, the first collector is arranged closer
to the second collector than the third collector, or vice versa.
Because of this, a slightly offset arrangement in terms of a height
of the first and second collector can be achieved, as a result of
which altogether a flatter design of the heat exchanger can be
achieved.
[0019] Furthermore, the present invention is based on the general
idea of equipping a thermal circuit, for example a coolant circuit
or a refrigerant circuit of an air conditioning or refrigeration
system, especially for a refrigerated trailer of a motor vehicle,
with at least one such heat exchanger according to the preceding
paragraphs. By way of this, the risk of freezing can be
significantly reduced but a heat exchanger output maintained at
least at the same level.
[0020] Further important features and advantages of the invention
are obtained from the subclaims, from the drawings and from the
associated figure description by way of the drawings.
[0021] It is to be understood that the features mentioned above and
still to be explained in the following cannot only be used in the
respective combination stated but also in other combinations or by
themselves without leaving the scope of the present invention.
[0022] Preferred exemplary embodiments of the invention are shown
in the drawings and are explained in more detail in the following
description, wherein same reference numbers relate to same or
similar or functionally same components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In the drawings,
[0024] FIG. 1 shows a heat exchanger according to the
invention,
[0025] FIG. 2 shows a further possible embodiment of the heat
exchanger according to the invention with angled first flat tubes,
and
[0026] FIG. 3 shows an embodiment analogous to FIG. 2, however with
first and second angled, bent or folded flat tubes.
DETAILED DESCRIPTION OF THE DRAWINGS
[0027] According to FIGS. 1 to 3, a heat exchanger 1 according to
the invention, especially for a refrigerated trailer of a motor
vehicle 2, comprises first flat tubes 3 which with a first
longitudinal end 4 are received in associated first openings 5 of a
first collector 6, for example of an inlet distributor or of an
outlet distributor, and with an opposite longitudinal end 7 in
associated second openings 8 of a second collector 9, for example
of a return distributor. Additionally provided are second flat
tubes 10 which with a first longitudinal end 11 are received in
associated third openings 12 of a third collector 13, for example
of an outlet distributor or of an inlet distributor.
[0028] According to the invention, either only the first flat tubes
3 now have an angled, bent or folded end region 14 (see FIGS. 1 and
2), or both the first flat tubes 3 and the second flat tubes 10
have such a bent end region 14 (see FIG. 3). The second flat tubes
10 are additionally received with an opposite second longitudinal
end 15 in associated fourth openings 16 of the second collector 9,
wherein the second openings 8 and the fourth openings 16 are
arranged spaced apart from one another alternating with spacing
allowing heat transfer fins 18 in between. In general this means,
that the openings 8 and 16 follow a 2n and 2n+1 arrangement, where
n.gtoreq.0.
[0029] With the embodiment of the heat exchanger 1 selected
according to the invention, a higher pressure drop can be achieved
through the U-shaped deflection of a fluid flow, for example of a
refrigerant, within the heat exchanger 1 from the first collector 6
via the first flat tubes 3, the second collector 9, the second flat
tubes 10 and the third collector 13, which reduces the risk of a
freezing of the fluid flowing in the heat exchanger 1. Through the
alternating arrangement of the flat tubes 3, 10 a defrosting
performance can be increased and thereby a defrosting cycle
shortened and an overall energy efficiency of the heat exchanger 1
increased. By both flat tubes 3, 10 opening into the second
collector 9, a mixing of the fluid flowing in the heat exchanger 1,
for example of the refrigerant, and thus an evening-out of the
temperature in the heat exchanger 1 can be achieved. Because of the
circumstance that the flat tubes 3, 10 are at least predominantly
arranged in one plane (see FIG. 1), a pressure drop of an airflow
flowing through the heat exchanger 1 can be additionally minimized
and thereby the efficiency of the heat exchanger 1 increased. By
way of the distance of the second openings 8 from the fourth
openings 16, a significantly improved flow circulation about of the
individual flat tubes 3, 10 and thus a higher heat transfer and a
higher heat exchanger output can thereby achieved.
[0030] Practically, a height L.sub.1 of the angled, bent or folded
region 14 can maximally to half of a total height L of the first
flat tubes 3 or of both flat tubes 3, 10, wherein preferably a
height L.sub.1 of the bent or angled region 14 of the first flat
tubes 3 or of both flat tubes 3, 10 maximally amounts to 20% of the
total height L of the first flat tubes 3 or of both flat tubes 3,
10. By way of this, a comparatively large region L-L.sub.1 can be
created, in which the two flat tubes 3, 10 are arranged stacked
above one another and parallel to one another, because of this
bring about merely a low air pressure drop. The minimizing of the
length "L1" simply maximizes the available heat transfer area.
Leading to increased performance and efficiency.
[0031] According to the embodiment of FIG. 2, the first collector 6
can also be arranged closer to the second collector 9 than the
third collector 13, as a result of which a shape of the heat
exchanger 1 is optimized in terms of a depth since it is flatter,
which in particular in cramped compartments is a major advantage.
In the embodiment according to FIG. 3, the first and third
collector 6, 13 are arranged in the air flow direction 17 one
behind the other which offers the major advantage that an area that
is available for the heat transfer is not negatively affected. The
embodiment according to FIG. 3 additionally offers the major
advantage that the first and second flat tubes 3, 10 are formed
identically and merely have to be inserted into the second
collector 9 flipped by 180.degree. in an alternating order.
[0032] The heat exchanger 1 according to the invention can be
incorporated in particular in a thermal circuit 20, for example in
a coolant circuit or a refrigerant circuit of an air conditioning
or refrigeration system of a refrigerated trailer of a motor
vehicle 2, where it brings significant advantages because of its
high heat exchanger output and its reduced risk of frost. The heat
exchanger 1 according to the invention can also be employed in heat
pump applications, for example as evaporator or as condenser,
wherein in an evaporator function the first collector 6 represents
an inlet distributor and the second collector 13 an outlet
distributor. In the condenser mode, this is reversed.
[0033] While the above description constitutes the preferred
embodiments of the present invention, the invention is susceptible
to modification, variation and change without departing from the
proper scope and fair meaning of the accompanying claims.
* * * * *