U.S. patent application number 13/382635 was filed with the patent office on 2012-08-09 for heat exchange system, as well as a method for the operation of a heat exchange system.
This patent application is currently assigned to A-Heat Allied Heat Exchange Technology AG. Invention is credited to Holger Koenig, Franz Summerer.
Application Number | 20120199310 13/382635 |
Document ID | / |
Family ID | 42027878 |
Filed Date | 2012-08-09 |
United States Patent
Application |
20120199310 |
Kind Code |
A1 |
Koenig; Holger ; et
al. |
August 9, 2012 |
Heat exchange system, as well as a method for the operation of a
heat exchange system
Abstract
The invention relates to a heat exchange system (1) including a
heat exchanger (2) with a flow passage (210) arranged in a flow
segment (21). For the exchange of heat between a transport fluid
(3) and a heat transfer medium (4) flowing through the flow passage
(210) in the operating state, the transport fluid (3) can be
brought into flowing contact with the heat exchanger (2) via an
inlet area (201) and can be led away again from the heat exchanger
(2) via an outlet area (202). In accordance with the invention, for
the determination of a degree of contamination (V) of the heat
exchanger (2), a contamination sensor (5) in the form of a pressure
sensor (5) and/or of a speed sensor (5) is provided with which a
transport parameter (TK) can be determined which is characteristic
for the flow of the transport fluid (3) from the inlet area (201)
via the outlet area (202). Furthermore, the invention relates to a
method for the operation of a heat exchange system (1).
Inventors: |
Koenig; Holger; (Kressbronn,
DE) ; Summerer; Franz; (Kottgeisering, DE) |
Assignee: |
A-Heat Allied Heat Exchange
Technology AG
Wien
AT
|
Family ID: |
42027878 |
Appl. No.: |
13/382635 |
Filed: |
July 7, 2009 |
PCT Filed: |
July 7, 2009 |
PCT NO: |
PCT/EP09/58632 |
371 Date: |
April 24, 2012 |
Current U.S.
Class: |
165/11.1 |
Current CPC
Class: |
F25B 2600/111 20130101;
F28B 1/06 20130101; F28F 2200/00 20130101; F28G 15/003 20130101;
F28F 2260/02 20130101; F25B 49/027 20130101; Y02B 30/743 20130101;
F28F 1/325 20130101; Y02B 30/70 20130101; F25B 47/00 20130101; F28F
19/00 20130101; F28F 1/128 20130101; F28B 11/00 20130101; F28F
27/00 20130101; F28D 1/05383 20130101 |
Class at
Publication: |
165/11.1 |
International
Class: |
F28F 27/00 20060101
F28F027/00 |
Claims
1. A heat exchange system including a heat exchanger (2) with a
flow passage (210) arranged in a flow segment (21), wherein for the
exchange of heat between a transport fluid (3) and a heat transfer
medium (4) flowing through the flow passage (210) in the operating
state, the transport fluid (3) can be brought into flowing contact
with the heat exchanger (2) via an inlet area (201) and can be led
away again from the heat exchanger (2) via an outlet area (202),
characterised in that, for the determination of the degree of
contamination (V) of the heat exchanger (2), a contamination sensor
(5) in the form of a pressure sensor (5) and/or of a speed sensor
(5) is provided with which a transport parameter (TK) can be
determined which is characteristic for the flow of the transport
fluid (3) from the inlet area (201) via the outlet area (202).
2. A heat exchange system in accordance with claim 1, wherein a fin
(6) is provided at a flow segment (21) to increase a heat exchange
rate.
3. A heat exchange system in accordance with claim 2, wherein a
through flow aperture (61) is provided at the fin (6), in
particular in the form of a louver (61).
4. A heat exchange system in accordance with claim 1, wherein at
least one heat exchanger (2) is a micro-passage heat exchanger
(2).
5. A heat exchange system in accordance with claim 1, wherein at
least one heat exchanger (2) is a tube heat exchanger (2).
6. A heat exchange system in accordance with claim 1, wherein a
transport apparatus (7) is provided, in particular a fan for the
transport of the transport fluid (3) from the inlet area (201) to
the outlet area (202).
7. A heat exchange system in accordance with claim 1, wherein the
transport parameter (TK) is a pressure of the transport fluid (3),
in particular a pressure loss (.DELTA.P) between the inlet area
(201) and the outlet area (202) of the heat exchanger (2).
8. A heat exchange system in accordance with claim 1, wherein the
transport parameter (TK) is a flow speed of the transport fluid
(3).
9. A heat exchange system in accordance with claim 1, wherein a
control unit, in particular a control unit having a data processing
unit, is signal connected with a sensor of the heat exchanger (2)
and/or with the transport apparatus (7) and/or with the
contamination sensor (5) and/or with a heat engine for the control
and/or regulation and/or for the purpose of a data collection of an
operating or status parameter of the heat exchange system.
10. A heat exchange system in accordance with claim 1, wherein the
heat exchange system is a radiator, in particular a radiator for a
motor vehicle, especially for a land vehicle, for an aircraft or
for a water vehicle, or a radiator, a condenser or a vaporiser for
a mobile or stationary heating plant, cooling plant or air
conditioning plant, in particular is a cooling device for a machine
for a data processing system or for a building.
11. A method for the operation of a heat exchange system (1) in
accordance with claim 1, wherein a transport parameter (TK) is
measured and a degree of contamination (V) of a heat exchanger (2)
is determined from the transport parameter (TK).
12. A method in accordance with claim 11, wherein a decrease in
pressure (.DELTA.P) is determined from the transport parameter
(TK).
13. A method in accordance with claim 11, wherein a decline in a
heat transfer performance (PW) of the heat exchanger (2) pressure
is determined from the pressure loss (.DELTA.P).
14. A method in accordance with claim 11, wherein a performance of
the transport apparatus (7), in particular a speed of rotation of
the fan (7), is controlled and/or regulated, in dependence on the
degree of contamination of the heat exchanger (2), and/or wherein a
time for a service routine is automatically determined in
dependence on the degree of contamination.
15. A method in accordance with claim 11, wherein in an online
method, in particular via an intranet or via the interne, operating
and/or status data from the heat exchange system (1) are monitored
by a control centre and/or the heat exchange system (1) is
controlled and regulated.
Description
[0001] The invention relates to a heat exchange system as well as
to a method for the operation and determination of a degree of
contamination of a heat exchange system in accordance with the
pre-characterising part of the independent claims 1 and 11.
[0002] The use of heat exchange systems is known from the prior art
in an overwhelmingly large number of applications. Heat exchangers
are used in refrigeration plants, such as in normal household
refrigerators, in air conditioning plants for buildings or in
vehicles of all kinds, above all in motor vehicles, aircraft and
ships, as water or oil radiators in combustion engines, as
condensers or vaporisers in coolant circuits, such as for example
in heat pumps and in further countless different applications which
indeed are all well-known to the person averagely skilled in the
art.
[0003] In this respect there are different ways of meaningfully
classifying the heat exchanger from completely different areas of
use. One attempt is to undertake a differentiation according to the
construction and/or the manufacture of the different types of heat
exchangers.
[0004] Thus, on the one hand, a division into so-called "fin heat
exchangers" which can also be referred to as "tube heat exchangers"
and, on the other hand into "mini passage heat exchangers" or
"micro-passage heat exchangers".
[0005] The fin tube heat exchangers, which have been well-known for
a very long time serve, as do all types of heat exchangers, for the
transfer of heat between two media, for example but not just, for
the transfer of one cooling medium to air or vice versa, such as is
known from a classic household refrigerator for example, in which
heat is given off to the environmental air via the heat exchanger
for the production of a refrigeration capacity in the interior of
the refrigerator.
[0006] The environmental medium outside the heat exchanger, i.e.
for example water, oil, or frequently simply the atmosphere which,
for example receives the heat or which transfers heat to the heat
exchanger is in this respect either correspondingly cooled or
heated. The second medium can be a liquid cold or heat transfer
medium or a vaporising or condensing "heat transfer medium". In
this respect within the scope of this application, the term "heat
transfer medium" is to be understood to mean any fluid, which can
be used advantageously in a heat exchanger. The term "heat transfer
medium" thus includes not only the classical refrigerants known in
technology, but also any other suitable heat transfer medium or
cooling means. If, for example, in a certain application the heat
exchanger is a simple radiator, for example a radiator in a
combustion engine, then the heat transfer medium can more
specifically naturally also be simple water or oil which circulates
though the heat exchanger as coolant.
[0007] In any case the environmental medium, in other words for
example, the air, has a considerably lower heat transfer
coefficient than the second medium, in other words for example the
coolant, which is circulating in the heat exchange system. This is
compensated by very different heat transfer surfaces for the two
media: The medium with the high heat transfer coefficient, in other
words the heat transfer means, flows in the tube, which due to thin
sheet metal parts (ribs, fins) has a greatly enlarged surface on
the outside, at which the heat transfer takes place with the air
for example.
[0008] FIG. 2 shows a heat exchange system in accordance with the
invention with a fin tube heat exchanger known per se. In this
regard the heat exchange system is formed in practice by a
plurality of such elements.
[0009] In this respect the proportion of external surface to
internal surface depends on the geometry of the fins (=tube
diameter, tube arrangement and tube spacing) and also on the
spacing of the fins. The spacing of the fins is selected
differently for different uses. However, from a purely
thermodynamic point of view it should be as small as possible, but
not so small such that the pressure loss on the air side is too
great. An economical ideal is approximately 2 mm, which is a
typical value for liquefiers and heat exchangers.
[0010] The manufacture of these so-called fin tube heat exchangers
takes place according to a standardized procedure which has been
known for a long time. The fins are punched using a press and a
special tool and placed together in packs. Subsequently the tubes
are pushed in and dilated, either mechanically or hydraulically, so
that a very good contact and thus a good heat transfer arise
between tube and fin. The individual tubes are then connected with
one another by bows and collecting and distributing tubes, often
being soldered together.
[0011] The degree of efficiency in this regard is essentially
determined by the fact that the heat, which is transferred between
the fin surface and the air, has to be transferred by means of heat
conduction through the fins to the tube. This heat transfer is all
the more effective, the higher the conductivity or the thickness of
the fin is, but also the smaller the space is between the pipes.
One speaks of the degree of fin efficiency in this regard. For this
reason aluminium is predominantly used as material for the fin
nowadays, which aluminium has a high thermal conductivity
(approximately 220 W/mK) at economic conditions. The tube spacing
should be as small as possible which, however, leads to the problem
that a lot of tubes are required. A high number of tubes mean high
costs, because the tubes (as a rule are made of copper) are
considerably more expensive than the thin aluminium fins. These
material costs could be reduced in that one reduces the tube
diameter and the wall strength, i.e. by building a heat exchanger
with a plurality of small tubes rather than with a few large tubes.
Thermodynamically this solution would be ideal: very many tubes
spaced closely together with small diameters. However, also the
working time for dilating and soldering the tubes is a crucial cost
factor. This would rise dramatically in such a scenario.
[0012] For this reason a new class of heat exchangers, so-called
mini-passage or micro-passage heat exchangers or also micro-channel
heat exchangers were developed several years ago, which are
manufactured by means of a completely different process and which
almost correspond to the ideal image of a fin tube heat exchanger:
a plurality of small tubes with narrow spacings therebetween.
[0013] Aluminium extrusions are used instead of small tubes in
micro-passage heat exchangers however, which have very many small
passages with a diameter of approximately 1 mm for example. An
extruded section such as this, likewise known per se, is used and
schematically illustrated in the embodiment of FIG. 1 in accordance
with the invention, for example. In this respect a heat exchanger,
depending on the heat output required can in practice make do with
a single extruded section as a central heat exchange element. In
order to achieve higher heat transfer performances, it goes without
saying that a plurality of extruded sections can also be provided
simultaneously, which for example are connected with one another or
soldered to one another in appropriate combinations, via inlet
pipes and outlet pipes.
[0014] Sections such as these can be manufactured simply and in
various shapes and from a plurality of materials in suitable
extrusion procedures for example. However, other manufacturing
methods are also known for the manufacture of mini-passage heat
exchangers, such as the putting together of appropriately shaped
sheet metal parts or other appropriate methods.
[0015] These sections cannot and do not need to be dilated and they
are also not pushed into punched fin packs. Instead sheet metal
strips, in particular aluminium strips are, for example laid
between two profiled sheet metal parts lying close together
(typical spacing for example <1 cm), so that a heat exchange
pack arises by means of the alternate placing of sheet metal strips
and sections. This pack is then soldered in its entirety in a
soldering oven.
[0016] This means that even when using the mini-passage heat
exchangers, fins are often likewise used in the same way as the fin
tube heat exchangers to increase the surface and for the
improvement of the heat transfer between the heat transfer medium,
which flows into the interior of the mini-passage heat exchanger
and the air, into which heat for example is to be released.
[0017] In this respect it is known in both types of heat exchangers
to provide the fin with slits, so-called "louvers". As the person
averagely skilled in the art certainly knows, these louvers are
mostly roof-shaped protrusions formed in the fin surface, through
which, on the one hand, air can flow for example, at which, on the
other hand, turbulences of the air can also form, so that an
effective contact time or an effective contact surface is
additionally increased between the air, with which heat is to be
exchanged and the fin, so that the efficiency of the heat exchange
can be increased further. This measure has also been known for a
long time, wherein the specific geometric design of the louver can
vary greatly, depending on the application. In the simplest case a
louver is simply a slit, in other words an elongated narrow groove
in the fin or an aperture in the fin.
[0018] Due to the narrow spaces and the small passage diameters in
the micro-passage heat exchangers a heat exchanger arises with a
very high degree of fin efficiency and with a very low filled
volume (inner side of the passage). The further advantages of this
technique are the avoidance of material pairings (corrosion), the
low weight (no copper), the high pressure stability (approximately
100 bar) as well as the compact type of construction (typical depth
of a heat exchanger for example, 20 mm).
[0019] Mini-passage heat exchangers have established themselves in
mobile use during the 1990's. The low weight, the low block depth
as well as the limited dimensions which are required here are the
ideal pre-requisites for this. Car radiators as well as liquefiers
and vaporizers for vehicle air conditioning units are almost
exclusively realized using mini-passage heat exchangers
nowadays.
[0020] On the one hand, larger heat exchangers are mostly required
for use in the stationary position, on the other hand it is not so
much the weight and the compactness which are foremost here but
rather far more the ideal value for money. Mini passage heat
exchangers were so-far limited in their dimensions to be suitable
for this application. A plurality of small modules would have had
to be connected in a complex and costly manner. Moreover, the use
of aluminium for extruded sections is relatively high, so that
hardly any cost advantage was to be expected through this use of
material.
[0021] Above all however the price of copper, which has risen
sharply in comparison with aluminium means that this technology is
also becoming increasingly interesting for stationary use.
[0022] In this regard a problem in all the previously known heat
exchange systems is the contamination of the system components of
the heat exchange system, in particular of the heat exchanger
itself, i.e. above all the fins of the heat exchanger, something
which is fundamentally unavoidable in the operating state.
[0023] Air-cooled heat exchangers, such as liquefiers or return
exchangers often work in contaminated environments. The
contamination of the air can be of a natural kind (pollen, insects,
dust, leaves etc.) or of an industrial kind (grinding dust, tire
abrasions, flour dust, cardboard dust etc.). Many contaminants
stick to the aircooled heat exchanger and clog it up over time.
[0024] The heat exchangers past which the cooling air is led for
example with the assistance of corresponding fans, can in time be
contaminated more and more by such contaminants and by other
contaminants of all kinds which are contained in the cooling air,
which can lead for example to the fact that the heat transfer
coefficient of the surface of the heat exchanger is reduced, so
that the heat transfer performance is considerably reduced. This
can lead to increased operating costs or in extreme cases the heat
exchange system is no longer able to produce the required heat
exchange performance at all, which can, in the worst cases lead to
serious damage.
[0025] In this regard the above-mentioned louvers are particularly
susceptible to contamination. These in particular offer a good
support for contaminations of all kinds. The contaminations collect
on the edges of the louvers in the fins and thus lead to a
deterioration in the heat transfer of the fin and thus to a loss of
performance of the heat exchanger, which as a result can lead to an
increase in the consumption of energy and even to a ceasing to
function.
[0026] The result of the contaminations is thus very often that the
resistance on the air side increases and as a result the volume of
air flow is reduced and the heat transfer is also reduced. This can
result in the fact that an engine which is to be cooled, such as a
data processing unit or a combustion engine or another engine
overheats and is damaged. Damage to goods, such as food for
example, which is stored in cold storage, can also perish due to
lack of cooling.
[0027] In this respect these problems arise both in fin tube heat
exchangers and also in micro-passage heat exchangers provided with
fins.
[0028] In order to prevent serious damage of this kind and to act
against contaminations such as these, the heat exchanger must
either be expensively cleaned regularly or else provided with a
corresponding filter. The filters must, however also be cleaned
regularly.
[0029] In this respect in the known systems the cleaning of the
heat exchanger is laborious and thus complicated and expensive, for
a start for reasons of construction, for example because in the
operating state the heat exchanger is not easily accessible. In
many known heat exchange systems it is necessary for example to
open a housing, in order to clean the heat exchanger itself or
other crucial components in the interior of the housing of the heat
exchange system, for example, or even just to check whether
cleaning is necessary or whether it may still be postponed. In this
respect the opening of the housing is not just time-consuming and
complicated. However, in this case as has already been mentioned,
the correspondingly connected heat engines have to be shut down,
since otherwise an opening of the housing of the heat exchange
system is not permitted for reasons of safety or is not possible at
all for technical reasons in the operating condition.
[0030] A further point is that a contamination which increases with
time can be cornpensated within certain limits by means of
appropriate control of the heat exchange system and/or regulation
of the heat exchange system, for example by matching a performance
of a fan, which conveys the air to the heat exchange through the
heat exchanger in dependence on the degree of contamination. Or in
that a throughflow or an operating pressure of a heat transfer
medium is readjusted by the heat exchanger or another operating
parameter is matched correspondingly.
[0031] However all these measures presuppose that the degree of
contamination of the heat exchange system has to be known and, what
is more, has preferably to be known not just qualitatively but also
quantifiably and especially the change in the contamination has to
be ascertainable.
[0032] It is therefore the object of the invention to make
available an improved heat exchange system which overcomes the
problems known from the prior art and which in particular permits
the continuous monitoring of the degree of contamination of the
heat exchange system, especially of the fin of the heat exchanger.
In particular a heat exchange system is to be proposed, in which,
within pre-determined limits, certain relevant operation parameters
can be adapted to the intrinsically changing contamination of the
heat exchange system, so that a heat transfer performance of the
heat exchanger or of the entire heat exchange system can also be
optimised over a long operating time, and a pre-determined heat
transfer performance is also guaranteed for long operating times,
even with increasing contamination. Furthermore, by means of the
invention it is to be ensured that a pre-determined degree of
contamination is automatically recognised, so that the ideal moment
for necessary cleaning work can be automatically recognised without
great expense.
[0033] The subject matter of the invention satisfying this object
are characterised by the features of the independent claims 1 and
11.
[0034] The dependent claims relate to particularly advantageous
embodiments of the invention.
[0035] The invention thus relates to a heat exchange system
including a heat exchanger with a flow passage arranged in a flow
segment. For the exchange of heat between a transport fluid and a
heat transfer medium flowing through the flow passage in the
operating state, the transport fluid can be brought into flowing
contact with the heat exchanger via an inlet area and can be led
away again from the heat exchanger via an outlet area. In
accordance with the invention for the determination of the degree
of contamination of the heat exchanger, a contamination sensor in
the form of a pressure sensor and/or of a speed sensor is provided,
with which a transport parameter can be determined which is
characteristic for the flow of the transport fluid from the inlet
area over the outlet area.
[0036] By means of the contamination sensor in accordance with the
invention, which monitors the characteristic transport parameter,
it is possible for the first time to automatically and continually
monitor a contamination of the heat exchange system which is
increasing with time, wherein a fall in performance of the heat
exchanger is already recognised by means of the contamination
sensor in accordance with the invention before the pressure loss
over the heat exchanger rises significantly. It is namely a crucial
recognition of the invention, which massively uses the decrease in
power of the heat exchanger, even at a degree of contamination at
which the increasing contamination of the heat exchanger is not yet
leading to an increase in the pressure loss over the heat
exchanger. On the contrary, this leads to a decrease in the
pressure loss over the heat exchanger at an earlier stage.
[0037] This means that it is possible for the first time, by means
of the present invention, to gain reliable information about the
performance or the change in performance of the heat exchanger from
the characteristic transport parameters of the heat exchanger, for
example from the fall in pressure over the heat exchanger or from a
flow speed of the transport fluid, for example of the air flowing
through the heat exchanger.
[0038] By this means an increasing contamination of the heat
exchange system can for example be compensated within certain
boundaries by suitable control and/or regulation of the heat
exchange system, for example in that a performance of a fan, which
conveys the air to the heat exchange by the heat exchanger, is
adjusted in its performance in dependence on the degree of
contamination. Or, however, in that a through flow of a heat
transfer medium or an operating pressure of a heat transfer medium
is appropriately readjusted by the heat exchanger or a different
parameter is appropriately modified.
[0039] In this regard in an embodiment which is particularly
relevant in practice, it is possible to continually determine the
degree of the contamination of the heat exchange system and what is
more, if necessary, not only quantitatively but also qualitatively,
wherein the change in the contamination can also be especially
determined in dependence on time. I.e. the degree of contamination
of the heat exchange system, especially of the fin of the heat
exchanger, can be continually monitored in the heat exchange system
in accordance with the invention.
[0040] This makes it possible, to systematically adjust certain
relevant parameters to the intrinsically changing contamination of
the heat exchange system within pre-determined limits, so that a
heat transfer performance of the heat exchanger or of the entire
heat exchange system can also be continually optimized during a
longer length of operation, as a result of which a pre-determined
heat transfer performance remains guaranteed, even during long
operating times. A pre-determined degree of contamination can be
automatically recognised by means of the invention, so that the
ideal point in time for necessary cleaning and maintenance can be
recognised automatically, without significant cost and
complexity.
[0041] In this regard the invention is based on the recognition,
that a characteristic transport parameter of the transport fluid is
dependent on the degree of contamination of the heat exchange
system in a clear and reproducible manner, in particular on the
degree of contamination of the heat exchanger.
[0042] In this connection the transport parameter can be a flow
speed of the transport fluid for example, in other words for
example a flow speed of the air through the heat exchanger. The
transport parameter can, however, also be a pressure of the
transport fluid, for example a pressure of the air before it enters
the heat exchanger via the inlet area, or a pressure during or
after the flowing out over the outlet area of the heat
exchanger.
[0043] The transport parameter is particularly preferably a
pressure difference or a pressure loss over the heat exchanger. As
will be explained in detail later with reference to FIG. 4 and FIG.
5, it has been shown in experiments, namely, that an increasing
contamination of the heat exchanger influences the pressure loss of
the flowing transport fluid in dependence on the degree of
contamination in a characteristic manner.
[0044] For example, a look-up table or a mathematical function can
be generated by means of corresponding calibration measurements,
which reflects the degree of contamination of the heat exchange
system, in dependence on the loss of pressure and/or of an absolute
pressure value and/or of a characteristic flow speed of the
transport fluid, wherein further parameters, such as for example
the speed of rotation of a fan, a temperature or other parameters
or operating parameters and condition parameters of the heat
exchange system are possibly to be taken into account. The person
averagely skilled in the art knows which particular parameters are
to be taken into account for the determination of the degree of
contamination and it goes without saying that it depends on the
actual design of a corresponding heat exchange system.
[0045] The invention can be used particularly advantageously in
heat exchangers, which include a fin for the increase of the
effective heat transfer surface, with the fin being preferably
equipped with the initially specified louvers.
[0046] In a completely surprising manner, the contamination of the
louver initially leads, namely, to a reduced loss of pressure, as
will be explained later with the help of FIG. 5. Here the loss of
pressure as a function of the degree of the contamination initially
falls to a minimum, in order to then rise again with progressive
contamination. This means that the loss of pressure over the heat
exchanger decreases initially with increasing contamination, not at
all what was expected.
[0047] It is a crucial recognition of the invention, that the
increasing contamination of the louver, in particular of the edges
but also of the aperture slits of the louver, reduces the
turbulence primarily at the edges of the louver or minimizes the
turbulence at the edges of the louver or in the case of
corresponding contamination, even prevented altogether, so that
fewer turbulences arise and thus the overall loss of pressure
through the flow passage formed by the fin is reduced. This means
that the loss of performance of the heat exchanger associated
therewith results from the reduction of the turbulence on the
louver, because the effective contact time or the effective contact
surface of the transport fluid with the heat exchanger is thus
reduced.
[0048] By exploiting this recognition, in a special embodiment a
very simple contamination sensor can be or is installed for the
measurement of the pressure loss at a heat exchange system in
accordance with the invention, which detects a reduction in the
fall in pressure through the heat exchanger and thus can measure
the degree of contamination, preferably in dependence on the time.
It should hereby specially be ensured that the amounts of air, to
which the respective loss of pressure over the heat exchanger is
measured are respectively essentially the same in the clean and the
contaminated condition. The speed of rotation of the fan and in
further environmental conditions should in other words preferably
be substantially the same between the clean and the contaminated
condition. To this end, in speed-regulated ventilators for example
in accordance with EC technology the charging rate of the engine
can be used as a signal, among other things.
[0049] As has already been mentioned more than once, in an
embodiment which is particularly important in practice, a fin can
be provided for the increase of a heat exchange rate at a flow
segment, wherein a through flow aperture is preferably provided on
the fin, in particular in the form of a louver.
[0050] In this regard at least one heat exchanger of a heat
exchanger in accordance with the invention is a micro-passage heat
exchanger and/or at least one heat exchanger is a tube heat
exchanger.
[0051] In practice in a heat exchange system of the present
invention a transport apparatus, in particular a fan is provided in
a manner known per se for the transport of the transport fluid from
the inlet area to the outlet area, wherein in practice the
transport fluid is very often the atmosphere.
[0052] As has likewise already been mentioned, the transport
parameter can be a pressure of the transport fluid, in particular a
loss in pressure between the inlet area and the outlet area of the
heat exchanger, and/or the transport parameter can be a flow speed
of the transport fluid and/or also another characteristic flow
property of the transport fluid.
[0053] Particularly advantageous for the control and/or regulation
and/or for the purpose of a recording of data of an operating
parameter or a condition parameter of the heat exchange system, is
a control unit, in particular a control unit with a data processing
unit which is signal connected to a sensor of the heat exchanger
and/or with the transport apparatus and/or with the contamination
sensor and/or with a heat engine for the control and/or regulation
and/or for the purpose of a data collection of an operating or
status parameter of the heat exchange system.
[0054] In this regard the heat exchange system can in practice be a
radiator, in particular a radiator for a motor vehicle, in the
special case for a land vehicle, for an aircraft or for a water
vehicle, or a radiator, a condenser or a vaporiser for a mobile or
a stationary heating plant, a cooling plant or an air conditioning
plant, in particular a cooling apparatus for an engine, a data
processing system or for a building.
[0055] The invention further relates to a method for the operation
of a described heat exchange system in accordance with the present
invention, wherein a transport parameter is measured and a degree
of contamination of the heat exchanger is determined from the
transport parameter.
[0056] In a particularly important embodiment for practice in this
regard, a decline in pressure over the heat exchanger is determined
from the transport parameter, wherein in particular a reduction of
a heat transfer performance of the heat exchanger can be determined
from the pressure loss.
[0057] In this regard a performance of the transport apparatus, in
particular a speed of rotation of the fan can be controlled and/or
regulated in dependence on the degree of contamination of the heat
exchanger and/or a time for a service routine is automatically
determined in dependence on the degree of contamination.
[0058] Advantageously in a heat exchange system in accordance with
the invention in an online method, in particular via an intranet or
via the internet, operating data and/or status data are monitored
by a control centre and/or the heat exchange system is controlled
and/or regulated in this manner.
[0059] The invention will be explained in more detail in the
following, with reference to the drawings. There is shown in
schematic illustration:
[0060] FIG. 1 a first embodiment of a heat exchange system in
accordance with the invention with a micro-passage heat
exchanger;
[0061] FIG. 2 a second embodiment in accordance with FIG. 1 with a
finned tube heat exchanger;
[0062] FIG. 3 an embodiment with a differential pressure
measurement for the determination of a loss of pressure;
[0063] FIG. 4 a loss of pressure at different degrees of
contamination in dependence on the flow speed of the transport
fluid;
[0064] FIG. 5 a loss of pressure and a performance curve in
dependence on the degree of contamination.
[0065] In FIG. 1 a schematic illustration of a first embodiment of
a heat exchange system with a micro-passage heat exchanger is
shown, which heat exchange system is referred to in its entirety
with the reference numeral 1 also in the following.
[0066] The heat exchange system 1 of FIG. 1 includes a heat
exchanger 2, which is a micro-passage heat exchanger 2 in the
present example, with a flow passage 201 arranged in a flow segment
21. For the exchange of heat between a transport fluid 3, which is
the atmospheric air in the present case, and a heat transfer medium
4 flowing through the flow passage 210 in the operating condition,
which heat transfer medium 4 for example is a refrigerant 4, such
as CO.sub.2, the transport fluid 3 is brought into flowing contact
with the heat exchanger 2 via an inlet area 201 and can be led away
again from the heat exchanger 2 via an outlet area 202. In
accordance with the present invention a contamination sensor 5 is
provided for the determination of a contamination of the heat
exchanger 2, which in the present example is arranged in the flow
direction of the air 3 upstream of the fin pack consisting of fins
6. The contamination sensor 6 is either a pressure sensor 6 or a
speed sensor 6 or a through flow sensor 6 or another appropriate
contamination sensor 6, with which a transport parameter TK, which
is characteristic for the flow of the transport fluid from the
inlet area 201 via the outlet area 202, can be determined.
[0067] The fin pack with the plurality of fins 6 each having a fin
surface 62 serves for the increase in a heat exchange rate between
the flow segment 21 and the transport fluid 3, which is atmospheric
air in the present example.
[0068] In the embodiment of FIG. 1 possibly present louvers are not
explicitly illustrated. Thus in a special embodiment according to
FIG. 1, louvers may be provided on the fin 6 and in a different
embodiment are not provided because for an appropriate difference
application no louvers are required.
[0069] In practice a fan 7 for the transport of air 3, which is not
illustrated in FIG. 1 for reasons of clarity, is provided for the
transport of the air 3 by the pack of fins 6, so that for example a
flow speed LG in accordance with FIG. 4 can be set, for example in
dependence on a strength of the contamination of the heat exchanger
2, which has been detected with the aid of the contamination sensor
5. In this regard the transport fluid air 3 is blown from the fan 7
through the pack of fins 6 in the direction of the arrow 3.
[0070] In FIG. 1, which relates to an embodiment in accordance with
the invention with a micro-passage heat exchanger 2, the plurality
of flow channels 210, which are micro-passages here, are clearly
visible.
[0071] FIG. 2 is distinguished from the embodiment of FIG. 2
essentially only by the fact, that instead of a micro-passage heat
exchanger, a classic finned tube heat exchanger is used, wherein
the louver 61 is clearly to be seen in the fins 6, which in the
example of FIG. 2 are not yet contaminated. A further distinction
from the example of FIG. 1 is in the fact that the contamination
sensor 5 is accommodated in the interior of the fin pack consisting
of fins 6.
[0072] It goes without saying that in each embodiment in accordance
with the invention further contamination sensors 5 are also
alternatively arranged at appropriate places or a plurality of
contamination sensors 5 can additionally be provided at the same
time.
[0073] For very special arrangements it is even possible that in
one and the same heat exchange system a micro-passage heat
exchanger 2 and a classic finned tube heat exchanger are provided
simultaneously.
[0074] A further embodiment which is very significant in practice
with differential pressure measurement for the determination of a
pressure loss .DELTA.P over the heat exchanger 2 is schematically
illustrated in FIG. 3. The fan 7 in a manner known per se conveys
environmental air 3 with the characteristic transport parameter TK
through the heat exchanger 2 via the inlet area 201 and guides the
air 3 through a cover A from the heat exchanger system 1 via the
outlet area 202 back to the environment.
[0075] For the determination of the pressure loss .DELTA.P during
the passing of the air 3 through the heat exchanger 2, a
contamination sensor 5 is provided respectively on the left-hand
side of the drawing in front of the inlet area 201 and on the
right-hand side of the drawing behind the outlet area 202, so that
the pressure loss (.DELTA.P) over the heat exchanger 2 can be
determined from a measured pressure difference.
[0076] It is to be understood that it is not really definitive for
the invention, which means are used to determine the pressure loss
.DELTA.P. A different differential pressure sensor known per se can
be used advantageously just as well.
[0077] In FIG. 4 finally a typical carpet plot of the
characteristic transport parameter TK for a heat exchange system 1
with a micro-passage heat exchanger 2 with fins 6 and louvers 61 is
schematically illustrated.
[0078] In the example of FIG. 4 the pressure loss .DELTA.P is shown
as a transport parameter TK at different degrees of contamination
V, (V.sub.0, V.sub.1, . . . up to V.sub.max) in dependence on the
flow speed LG of the transport fluid 3. The person averagely
skilled in the art has no problems understanding that one can also
plot corresponding carpet plots for other transport parameters TK,
for example for the through flow amount etc. and, it goes without
saying also for other types of heat exchangers, for example for a
finned tube heat exchanger.
[0079] The curve V.sub.0 belongs to a heat exchange system 1, which
was freshly cleaned, in other words is not yet contaminated. The
curve V.sub.1 of the characteristic curve was recorded in the same
heat exchange system 1 after a certain length of operation. The
heat exchanger 2 is now already considerably more contaminated,
which can be recognised in the correspondingly small pressure loss
.DELTA.P. The curve V.sub.1 is shallower than the curve V.sub.0,
which belongs to the uncontaminated heat exchanger 2. After further
operation the heat exchanger 2 becomes more and more contaminated,
until it finally displays the maximum permitted contamination via
V.sub.2, V.sub.3 etc. in the curve V.sub.max and has to be cleaned
again.
[0080] Finally FIG. 5 shows in schematic illustration a
characteristic diagram, that explains the connection between the
degree of contamination V and the alteration in the pressure loss
.DELTA.P resulting from this and also the reduction in the heat
transfer performance PW of the heat exchanger 2 which is associated
with this.
[0081] The degree of contamination V of the heat exchanger 2 is
illustrated on the horizontal abscissa, which increases from the
left towards the right in the drawing, wherein the pressure loss
.DELTA.P through the heat exchanger 2 is shown on the left-hand
axis of ordinates .DELTA.P, whereas on the right-hand axis of
ordinates PW the decline in the heat transfer performance PW
resulting from the increasing degree of contamination V is
simultaneously to be read out.
[0082] The solid line .DELTA.P corresponds in this regard to the
course of the pressure loss .DELTA.P in dependence on the degree of
contamination V, whereas the dotted line shows the decline in the
heat transfer performance PW in dependence on the degree of
contamination V. In this regard the pressure loss .DELTA.P and the
heat transfer performance PW are identically zero at a degree of
contamination V, i.e. each respectively normed to 100% for the not
contaminated heat exchanger 2.
[0083] At an even slighter contamination V the fall in pressure
.DELTA.P over the heat exchanger remains almost constant initially
up to a critical degree of contamination VK, from which the
pressure loss .DELTA.P suddenly and significantly decreases with an
increasing degree of contamination, until the value of the pressure
loss .DELTA.P reaches a minimum value at a degree of contamination
Vm. At the same time the heat transfer performance PW falls
rapidly. Prior to a contamination interval and during the
contamination interval between Vk and Vm, only the louvers are
initially clogged with dirt particles, which leads to the fact that
turbulences of the transport fluid 3, in other words for example
the air 3 flowing through the heat exchanger 2 is reduced even
more, the stronger the louvers 61 are clogged up with dirt. By this
means the air 3 can pass through the heat exchanger 2 more easily
and/or faster. On the one hand, this results in a reduction in the
loss of pressure .DELTA.P, and, on the other hand leads to the fact
that the effective contact time or the effective contact surface
between the transport medium 3 and the heat exchanger 2 is reduced,
which results in the observed massive reduction in the heat
transfer performance PW.
[0084] With even greater contamination the loss of pressure
.DELTA.P increases again. The reason for this is that now the
intermediary spaces between the individual fins, into which the
louvers are worked are increasingly clogged up with dirt, so that
increasingly less air 3 can be transported through the heat
exchanger at the same fan performance per unit of time.
[0085] In this regard it is crucial, that in the vicinity of the
minimum of the loss of pressure .DELTA.P the heat transfer
performance PW has already sunk to a no longer tolerable level, in
the present special example has already fallen to 50% of the
maximum possible heat transfer performance PW.
[0086] It is thus a crucial recognition of the invention that a
cleaning of the heat exchanger is not to be undertaken at an
increase in the loss of pressure .DELTA.P but much earlier, namely
in a phase when the loss of pressure .DELTA.P is falling
significantly.
[0087] Thus, with the present invention the maintaining of cleaning
intervals can be ideally guaranteed, on the one hand, and on the
other hand an ideal operation of the heat exchange system in
accordance with the invention can be guaranteed. Furthermore, the
quasi automatic occurring electronic signals are also available for
other purposes and can for example also be used to advantage for
different maintenance purposes.
* * * * *