Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Ammonia water absorption chiller unit
The present invention relates to ammonia water absorption chiller units
comprising at
least one absorber arranged in a refrigerant cycle.
The present invention furthermore relates to a method of minimum complexity
for
leading media in at least one cycle of an ammonia water absorption chiller
unit in
consideration of the thermodynamic particularities of binary diphase mixtures.
The use of an absorber in connection with an ammonia water absorption chiller
unit
according to the invention and/or a method according to the invention is
furthermore a
subject of the present invention.
The principle of absorption refrigeration by means of the substance
combination of
ammonia and water has been known for about 200 years and is mainly used for
high
refrigerating capacities in the range comprised between about 200 kW and about
6,500
kW today for reducing costs. Installations of this kind, such as for example
described in
DE 20 2007 007 999 U1 require a complex process technology and drive
temperatures
of clearly more than 100 C for cooling temperatures beneath 0 C.
Based upon these facts, an ammonia water absorption chiller unit of minimum
complexity shall be provided by using presently available technologies and new
calculation methods for the heat and substance transfer, which chiller unit
permits a
more economic application of the cooling principle also for refrigerating
capacities of
less than 100 kW. In the literature relevant to the subject, see for example
VDI
Warmeatlas (originally published by VDI-Verlag, Dusseldorf. 10th revised and
enlarged
edition 2006, ISBN: 978-3-540-25504-8), no calculation methods are known for
this.
Thus, up to the present the man skilled in the art does not know any concrete
dimensioning guide-lines or methods in order to dimension the individual
components of
ammonia water absorption chiller units of minimum complexity for an
industrially usable
ammonia water absorption refrigerating machine and to select them
correspondingly,
wherein cooling temperatures beneath 0 C shall be in particular achievable
with drive
temperatures of less than 100 C.
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For technically solving the problem, the invention proposes an ammonia water
absorption chiller unit comprising at least one absorber arranged in a
refrigerant cycle,
which is characterized in that the absorber comprises a fully welded packet of
plates for
an inner medium which is in turn placed in a casing for an outer medium.
Herein, the invention makes in particular use of the knowledge that if fully
welded tube
plate exchangers are exclusively used for the absorber of an ammonia water
absorption
chiller unit, cooling temperatures of beneath 0 C can be achieved even with
drive
temperatures of less than 100 C with a corresponding dimensioning. Ammonia
water
absorption chiller units according to the invention are especially suitable
for. solar
thermal cooling systems and have been unknown hitherto in the state of the
art. Herein,
the present invention is stamped by a new simplified circuit. In another
embodiment of
the invention, highly efficient heat transmitting components are proposed, the
combinations of which according to the invention go far beyond the solutions
which
have been hitherto known in the state of the art. The present state of the art
proceeds
on the assumption that due to the high gas flow rate and the pressure losses
related
thereto, an efficient substance and heat transfer in an absorber of an ammonia
water
absorption chiller unit can only be obtained by using tubular heat exchangers.
According
to the invention it has been found that if the numerous parameters of an
ammonia water
absorption chiller unit are carefully calculated, an efficient heat and
substance transfer
can be just or especially be achieved by means of tube plate exchangers.
Herein, it has
surprisingly been found that if fully welded tube plate exchangers are
exclusively used
for the absorber of an ammonia water absorption chiller unit, cooling
temperatures of
beneath 0 C can be obtained even with drive temperatures of clearly less than
100 C,
in particular if a binary ammonia water diphase mixture is used.
Fully welded packets of plates which can be used according to the invention
for the
absorber are typically disclosed in for example EP 1 559 981 A2 or DE 601 12
767 T2,
the disclosures of which are explicitly referenced herewith.
For dimensioning ammonia water absorption chiller units according to the
invention with
the object of a highly efficient heat and substance transfer, .the plate
geometry of fully
welded tube plate exchangers used for the absorber is advantageously adapted
to or for
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turbulent flow conditions with pressure losses of less than 0.1 MPa in.
particular..
consideration of the thermodynamic parameters of substance mixtures for
leading the
media. An adaptation to or for turbulent flow conditions is advantageously
realized with
flow rates comprised between 0.05 m/s and 1 m/s and with pressure losses of
less than
0.1 MPa. Under these special conditions, drive temperatures beneath 100 C can
also
be made usable in an economic way according to the invention.
In an advantageous embodiment of the invention, the absorption takes place in
the
casing of the absorber of the ammonia water absorption chiller unit according
to the
invention and the generated solution which is high in refrigerant is pre-
stored in the
same one. Thus, the solution collector which is otherwise common in the state
of the art
can be saved according to the invention. The number of building components of
an
absorption chiller unit can thus be reduced and furthermore a compact
structure is
achieved. In dependence on the respective application and the required
capacity, an
ammonia water absorption chiller unit according to the invention can be
realized in
numerous different variants and embodiments, according to the respective need.
In another advantageous embodiment of the invention an evaporator is
advantageously
arranged in the refrigerant cycle of the ammonia water absorption chiller
unit, after or
behind which evaporator, the absorber follows in flow direction. Thereby the
flow
dependent pressure losses are reduced and the efficiency of an ammonia water
absorption chiller unit according to the invention is further improved. The
evaporator
advantageously comprises a fully welded packet of plates for an inner medium,
which is
in turn arranged in a casing for an outer medium. In the packet of plates, a
change of
phases of the liquid refrigerant into the gaseous state preferably occurs.
Herein, the
refrigerant constantly withdraws the heat from the medium in the casing of the
refrigerating agent cycle which shall be cooled by means of the absorption
chiller unit.
The currents in the packet of plates and in the casing of the evaporator are
preferably
guided in reverse currents with respect to each other. Fully welded packets of
plates
which can be used according to the invention for the evaporator are typically
disclosed
by for example EP 1 559 981 A2 or DE 601 12 767 T2.
In another advantageous embodiment of the invention, a desorber (desorption
unit) is
advantageously arranged in the refrigerant cycle of the ammonia water
absorption
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chiller unit, advantageously comprising a - fully welded packet of . plates
for an inner
medium which is in turn arranged in a casing for an outer medium. In the
desorber,
preferably in the packet of plates, a change of phases of the refrigerant
bearing solution
from the liquid into the gaseous state occurs. Herein, the refrigerant bearing
solution is
constantly supplied with heat by a medium in the casing of the heating cycle
which
drives or shall drive the absorption chiller unit. The currents in the packet
of plates and
in the casing of the desorber are preferably guided in reverse currents with
respect to
each other. The desorber is advantageously arranged after the absorber in the
refrigerant flow direction. Thanks to these measures according to the
invention, taken
individually or in combination with each other, the efficiency of an ammonia
water
absorption chiller unit will be further improved. Fully welded packets of
plates which can
be used according to the invention for the desorber are typically disclosed by
for
example EP 1 559 981 A2 or DE 601 12 767 T2.
In another advantageous embodiment of the invention, a condenser is
advantageously
arranged in the refrigerant cycle of the ammonia water absorption chiller
unit,
advantageously comprising a fully welded packet of plates for an inner medium
which is
in turn arranged in a casing for an outer medium. In the condenser, preferably
in the
casing, a change of phases of a refrigerant bearing vapor from the gaseous
into the
liquid state occurs, wherein the generated refrigerant bearing condensate will
be pre-
stored in the same one. Thereby, the refrigerant collector which is otherwise
common in
absorption chiller units according to the state of the art can be saved. The
number of
building components of an ammonia water absorption chiller unit is thus
reduced and a
compact structure is enabled. Herein, the refrigerant bearing vapor constantly
conveys
heat to a medium in the packet of plates of the recooling cycle which serves
as heat
sink to the ammonia water absorption chiller unit according to the invention.
The
currents in the packet of plates and in the casing of the condenser are
preferably guided
in reverse currents with respect to each other. The condenser is
advantageously
arranged before the evaporator of an ammonia water absorption chiller unit
according to
the invention in the refrigerant flow direction. Thanks to these measures
according to
the invention, taken individually or in combination with each other, in
particular the
efficiency of an ammonia water absorption chiller unit will be further
improved. Fully
welded packets of plates which can be used according to the invention for the
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condenser are typically disclosed by for example EP .1 559:-981 A2 or DE 601.
12 767
T2.
In another advantageous embodiment of the invention, a solution heat exchanger
is
advantageously arranged in the refrigerant cycle of the ammonia water
absorption
chiller unit, advantageously comprising a fully welded packet of plates for an
inner
medium which is in turn arranged in a casing for an outer medium. In the
solution heat
exchanger, a refrigerant bearing solution which shall be supplied to the
desorber will be
internally pre-heated. The currents in the packet of plates and in the casing
of the
solution heat exchanger are preferably guided in reverse currents with respect
to each
other. Thereby, the external heat supply will be reduced in the desorber and
the
efficiency of an ammonia water absorption chiller unit according to the
invention will be
further improved. The solution heat exchanger is preferably arranged between
the
absorber and the desorber in the refrigerant flow direction. Thanks to these
measures
according to the invention, taken individually or in combination with each
other, in
particular the efficiency of an ammonia water absorption chiller unit
according to the
invention will be further improved. Fully welded packets of plates which can
be used
according to the invention for the solution heat exchanger are typically
disclosed by for
example EP 1 559 981 A2 or DE 601 12 767 T2.
In another advantageous embodiment of the invention, a dephlegmator is
advantageously arranged in the refrigerant cycle of the ammonia water
absorption
chiller unit at drive temperatures of more than 100 C, advantageously
comprising a fully
welded packet of plates for an inner medium which is in turn arranged in a
casing for an
outer medium. In the dephlegmator, preferably in the packet of plates a
refrigerant
bearing vapor which shall be supplied to the condenser conveys heat.to a
medium in
the casing, wherein a part of the refrigerant bearing vapor already condenses.
Thereby
it is achieved that only small quantities of solvent vapor reach the
condenser. The
dephlegmator is preferably arranged before the condenser in the refrigerant
flow
direction. Thanks to these measures according to the invention, taken
individually or in
combination with each other, in particular the efficiency of an ammonia water
absorption
chiller unit according to the invention will be further improved. Fully welded
packets of
plates which can be used according to the invention for the dephlegmator are
typically
disclosed by for example EP 1 559 981 A2 or DE 601 12 767 T2.
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According to an especially advantageous embodiment of the invention it is
possible to
omit building components which have been hitherto assumed as necessary or
required
in the state of the art. It has been found that at drive temperatures of less
than 100 C
the portion of vaporous solvent in the refrigerant bearing vapor is usually
less than 5%,
such that according to the need in particular a dephlegmator can be saved
according to
the invention.
In another advantageous embodiment of the invention, a refrigerant
supercooling unit is
arranged in the refrigerant cycle of the ammonia water absorption chiller
unit,
advantageously comprising a fully welded packet of plates for an inner medium
which is
in turn arranged in a casing for an outer medium. In the refrigerant
supercooling unit,
the temperature of the condensed refrigerant which shall be supplied to the
evaporator
is reduced beneath the boiling point. Thereby it is achieved according to the
invention
that, on the one hand, no premature evaporation occurs with pressure losses
and, on
the other hand, the amount of the evaporation enthalpy is increased which
further
improves the efficiency of an ammonia water absorption chiller unit according
to the
invention. The currents in the packet of plates and in the casing of the
refrigerant
supercooling unit are preferably guided in reverse currents with respect to
each other.
The refrigerant supercooling unit is preferably arranged between the
evaporator and the
condenser, on the one hand, and between the evaporator and the absorber, on
the
other hand, in the refrigerant flow direction. Fully welded packets of plates
which can be
used according to the invention for the refrigerant supercooling unit are
typically
disclosed by for example EP 1 559 981 A2 or DE 601 12 767 T2.
According to an especially advantageous embodiment of the invention it is
possible to
omit building components which have been hitherto assumed as. necessaryor
required
in the state of the art. It has been found that with a cooling capacity of the
evaporator of
less than 100 kW, the refrigerant supercooling unit can also be saved, in
particular since
with a cooling capacity of the evaporator of less than 100 kW the contribution
of a
refrigerant supercooling unit to increasing the efficiency of an ammonia water
absorption chiller unit according to the invention does not justify the
technical
expenditure and the costs related thereto for an efficient use.
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The refrigerant contained in the refrigeration cycle is preferably ammonia or
comprises
ammonia. The solvent contained in the refrigeration cycle is preferably water
or
comprises water.
In another advantageous embodiment of the invention, the feeding pipes and/or
draining pipes to the condenser and/or the absorber in the refrigerant flow
direction are
provided with a pressure compensation pipe. Thereby, pressure losses are
reduced and
a more uniform heat transfer is enabled. Thanks to this measure which is
unusual in the
state of the art the efficiency of the absorption of refrigerant in sorbent
and thus the
efficiency of an ammonia water absorption chiller unit according to the
invention will be
further improved.
The invention furthermore relates to ammonia water absorption chiller units
comprising
an absorption refrigeration method of minimum complexity for leading media in
at least
one refrigerant cycle using heat exchangers which comprise a fully welded
packet of
plates for an inner medium which is in turn arranged in a casing for an outer
medium.
Fully welded packets of plates which can be used according to the invention
are
typically disclosed by for example EP 1 559 981 A2 or DE 601 12 767 T2.
According to the invention, it is proposed that in particular consideration of
the
thermodynamic of substance mixtures for leading the media the plate geometry
is
adapted to turbulent flow conditions with pressure losses of less than 0.1 MPa
for a
particularly efficient heat and substance transfer. An adaptation to or for
turbulent flow
conditions is advantageously realized with flow rates comprised between 0.05
m/s and
I m/s and with pressure losses of less than 0.1 MPa. According to the
invention, it
becomes simultaneously possible thereby to obtain a compact construction of
ammonia
water absorption chiller units according to the invention. In dependence on
the
respective application and the required capacity, the embodiment according to
the
invention can be realized in numerous different variants, according to the
respective
need. Herein, the modular graduation and adaptation of fully welded tube plate
exchangers permits to use the method with cooling capacities comprised between
the
kilowatt range and the megawatt range and the method can thus considerably
contribute to an economic use of energy advantageously.
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Logically, the invention furthermore relates to an absorber which is
configured.as.fully..
welded packet of plates for an inner medium which is in turn arranged in a
casing for an
outer medium, in a refrigerant cycle of an ammonia water absorption chiller
unit
according to the invention in particular having one or more of the above
mentioned
characteristics.
The embodiments according to the invention and the knowledge gained by them
permit
an optimization of the individual tube plate exchangers, lead to a high
efficiency and
allow a compact construction of ammonia water absorption chiller units which
has been
hitherto unknown and inaccessible in the state of the art.
Other details, characteristics and advantages of the invention will be
explained in detail
in the following by means of the exemplary embodiment of the invention which
is
represented in the figure of the drawing. Herein:
Fig. 1 is a block diagram which shows an exemplary embodiment of an ammonia
water
absorption chiller unit according to the invention.
Fig. 1 shows an ammonia water absorption chiller unit 1 comprising an absorber
10, an
evaporator 20, a condenser 30, a desorber 40, a solution heat exchanger 50, a
dephlegmator 60 and a refrigerant supercooling unit 70 which are arranged in a
refrigerant cycle 2. Furthermore, pressure compensation pipes 80, 90 realize a
connection in the refrigerant flow direction 3 between the feeding and
draining .pipe of
the absorber 10 or the condenser 30 in order to reduce pressure losses and to
permit a
more uniform heat transfer.
The refrigerant contained in the refrigerant cycle 2 flows into the
refrigerant flow
direction 3 which is symbolically represented by means of an arrow and is
supplied by
means of a pump 100 into the desorber 40. The principal functioning of an
absorption
chiller unit is presently taken for granted (cf. in particular Handbuch der
Kaltetechnik,
vol. 7, sorption refrigerating machines, Wilhelm Niebergall, 1959). The drive
energy is
introduced and discharged via a heating medium through the connections 41 and
42
into or from the desorber 40. The cooling effect is transferred by means of a
refrigerant
medium in the evaporator 20 through the connections 21 and 22. The recooling
of the
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-ammonia water absorption chiller unit 1 is realized by a heat transfer-medium
in the
absorber 10 through the connections 11 and 12 as well as in the condenser
through the
connections 31 and 32. The design of the heat exchanger which comprises a
fully
welded packet of plates for an inner medium which is turn arranged in a casing
for an
outer medium principally follows the disclosures of EP 1 559 981 A2 or DE 601
12 767
T2, the disclosures of which are explicitly referenced herewith. The plate
geometry of a
fully welded packet of plates according to the invention is advantageously
adapted to
turbulent flow conditions with flow rates comprised between 0.05 m/s and 1 m/s
and
with pressure losses of less than 0.1 MPa in particular consideration of the
thermodynamic of substance mixtures for leading the media for a particularly
efficient
heat and substance transfer.
The improvement of the invention presently refers to a reduction of components
of an
absorption chiller unit which has been hitherto regarded as impossible or
unrealizable in
the state of the art and which components have been hitherto regarded as
required and
necessary. The results and calculations of the present invention show that the
dephlegmator 60 can be saved with drive temperatures of less than 100 C. The
same is
true for the refrigerant supercooling unit 70 with a cooling capacity of the
evaporator of
less than 100 kW. Under these circumstances, ammonia water absorption chiller
units 1
of minimum complexity are obtained which allow an economic application of the
cooling
principle also for cooling capacities of less than 100 kW, at drive
temperatures of less
than 100 C and cooling temperatures of less than 0 C.
The exemplary embodiments of the invention represented in the figure of the
drawing
and described in connection with this one only serve for explaining the
invention and are
not limiting to this one.
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List of reference numerals
I absorption chiller unit
2 refrigerant cycle
3 refrigerant flow direction
absorber
11 connection
12 connection
evaporator
21 connection
22 connection
condenser
31 connection
32 connection
desorber
41 connection
42 connection
solution heat exchanger
dephlegmator
refrigerant supercooling unit
pressure compensation pipe
pressure compensation pipe
100 pump
