U.S. patent application number 10/896258 was filed with the patent office on 2005-01-27 for cooling system.
This patent application is currently assigned to Deere & Company, a Delaware corporation. Invention is credited to Sobotzik, Joachim, Tarasinski, Nicolai.
Application Number | 20050016193 10/896258 |
Document ID | / |
Family ID | 33483005 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050016193 |
Kind Code |
A1 |
Tarasinski, Nicolai ; et
al. |
January 27, 2005 |
Cooling system
Abstract
A cooling system for an agricultural vehicle, such as a tractor
driven by an internal combustion engine includes a main cooling
system containing a coolant. The cooling system includes a sorption
cooling system which includes an evaporator for evaporating a
refrigerant, a sorption chamber for the sorption of the refrigerant
vapor, a desorption chamber for the desorption of the refrigerant
from the sorbent, and a condenser for condensing the refrigerant.
An exhaust gas stream from the engine is conducted to the
desorption chamber to provide the heat necessary for the
desorption. The evaporator is used for additional cooling of the
coolant of the main cooling system and/or for cooling a second
exhaust gas stream from the engine.
Inventors: |
Tarasinski, Nicolai;
(Frankenthal, DE) ; Sobotzik, Joachim; (Lambsheim,
DE) |
Correspondence
Address: |
Joel S. Carter
Patent Department
DEERE & COMPANY
One John Deere Place
Moline
IL
61265-8098
US
|
Assignee: |
Deere & Company, a Delaware
corporation
|
Family ID: |
33483005 |
Appl. No.: |
10/896258 |
Filed: |
July 21, 2004 |
Current U.S.
Class: |
62/238.3 ;
62/476; 62/497 |
Current CPC
Class: |
F02B 29/0412 20130101;
F01P 2060/02 20130101; F02M 26/43 20160201; F02M 26/01 20160201;
F02B 29/0443 20130101; Y02T 10/166 20130101; F02B 29/0475 20130101;
Y02T 10/12 20130101; B60H 1/32011 20190501; F02G 5/02 20130101;
B60H 1/32014 20190501; F02M 26/28 20160201; F25B 27/02 20130101;
B60H 1/3201 20130101; F02M 26/04 20160201; F25B 2339/047 20130101;
F25B 15/00 20130101; F02B 29/0481 20130101; Y02A 30/274 20180101;
F01P 9/06 20130101; Y02T 10/146 20130101 |
Class at
Publication: |
062/238.3 ;
062/497; 062/476 |
International
Class: |
F25B 027/00; F25B
015/00; F25B 033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 22, 2003 |
DE |
103 33 219.7 |
Claims
We claim:
1. A cooling system for an engine driven agricultural vehicle
having a main cooling arrangement with a main cooling medium, the
cooling system comprising: a sorption cooling system including an
evaporator for evaporating a refrigerant, a sorption chamber
containing an absorber for absorbing refrigerant vapor, a
desorption chamber for desorption of the refrigerant from the
absorber, and a condenser for condensing the refrigerant, the
evaporator cooling the main cooling medium; and an exhaust gas
conduit communicating a first engine exhaust gas stream to the
desorption chamber to provide heat required by the desorption
chamber.
2. The cooling system of claim 1, wherein: the main cooling system
comprises a charge air cooling system and the evaporator cools the
charge air cooling system.
3. The cooling system of claim 1, further comprising: a second
engine exhaust gas stream branched off from an exhaust gas stream
which is communicated to the environment.
4. The cooling system of claim 1, wherein: the main cooling system
comprises an engine cooling system, and the evaporator cools the
engine cooling system.
5. The cooling system of claim 1, wherein: the main cooling system
comprises an air conditioner cooling system which conditions a cab
air stream, and the evaporator cooling the cab air stream.
6. The cooling system of claim 3, wherein: the evaporator cools the
first engine exhaust gas stream.
7. The cooling system of claim 1, wherein: a cooler is connected to
the condenser, the cooler removing heat from the condenser.
8. The cooling system of the preceding claims, wherein: a cooler is
connected with the sorption chamber, the cooler removing heat from
the sorption chamber.
9. A cooling system for an engine driven agricultural vehicle
having a main cooling arrangement with a main cooling medium, the
cooling system comprising: a sorption cooling system including an
evaporator for evaporating a refrigerant, a sorption chamber
containing an absorber for absorbing refrigerant vapor, a
desorption chamber for desorption of the refrigerant from the
absorber, and a condenser for condensing the refrigerant; a first
exhaust gas conduit communicating a first engine exhaust gas stream
to the desorption chamber to provide heat required by the
desorption chamber; and a second exhaust gas conduit communicating
a second engine exhaust gas stream from the engine, the evaporator
cooling both the main cooling medium and the second exhaust gas
stream.
10. A cooling system for an engine driven agricultural vehicle
having a main cooling arrangement with a main cooling medium, the
cooling system comprising: a sorption cooling system including an
evaporator for evaporating a refrigerant, a sorption chamber
containing an absorber for absorbing refrigerant vapor, a
desorption chamber for desorption of the refrigerant from the
absorber, and a condenser for condensing the refrigerant; a first
exhaust gas conduit communicating a first engine exhaust gas stream
to the desorption chamber to provide heat required by the
desorption chamber; and a second exhaust gas conduit communicating
a second engine exhaust gas stream from the engine, the evaporator
cooling the second exhaust gas stream.
Description
BACKGROUND
[0001] The present invention relates to an engine driven
agricultural tractor cooling system with a main cooling system
containing a coolant.
[0002] Increasing power output of engines and stricter emission
control regulations increases the demands on a vehicle cooling
system. The rate of thermal output that can be rejected by a
conventional cooling system is essentially determined by parameters
such as the size of the surface of a cooler, heat transmission
coefficients, flow velocities of the coolant, and by temperature
differences of the associated media (surroundings, coolant, etc.).
In agricultural vehicles, particularly in tractors, the thermal
output of conventional cooling systems is determined generally by
the size of the available space of the configuration and the
maximum allowable temperature difference. For a water-based cooling
system, cooling this maximum temperature difference is a result of
the maximum surrounding temperature and the highest allowable
cooling water temperature.
[0003] Various cooling systems are known which achieve more
efficient cooling with maximum prevailing temperature differences.
For example, published German patent application DE 198 54 544
describes a cooling system for a supercharged engine with an
improved cooling capacity. This cooling system includes a high
temperature cooling circuit and a low temperature cooling circuit.
The high temperature cooling circuit includes in a main branch, the
engine, a high temperature re-cooler, and a branch circuit with a
high temperature charge air cooler. The low temperature cooling
circuit includes a low temperature re-cooler in series with a low
temperature charge air cooler. Furthermore, this system also
includes an engine oil/gearbox oil heat exchanger and a heat
exchanger for cooling electronic components. Thus, the heat
rejected in the engine oil/gearbox oil heat exchanger is rejected
at a relatively high temperature level, while the electronic
components and the charge air is cooled simultaneously at a lower
temperature. However, this cooling system is costly, and the
resulting temperature levels are not appropriate for the cooling of
a supercharged engine of an agricultural tractor.
[0004] Other cooling systems are known that are based on the
principle of the sorption cooling, in which cold is primarily
generated from heat. Such systems are gaining importance,
particularly in connection with air conditioned vehicles.
Adsorption and absorption refrigeration machines are described in
various publications, for example, Andreas Gassel, "Die
Adsorptionskaeltemaschine-Betriebserfahrungen und thermodynamische
Berechnung"-"The adsorption refrigeration machine--Operating
experience and thermodynamic calculations"; Article draft for Ki
air and refrigeration technology or York International "Prinzip
Absorptionskaltemaschine"-"Principles of absorption refrigeration
machine", prospectus KK14300). DE 199 27 879 A1 describes a vehicle
air conditioning system with an adsorption refrigeration
arrangement. The system includes an adsorption refrigeration
arrangement in which liquid refrigerant is evaporated, in order to
extract the heat required for it from a liquid or gaseous medium
for the generation of low temperatures. The evaporated refrigerant
is conducted to a sorbent to be adsorbed. The sorbent loaded with
refrigerant is heated in order to desorb the refrigerant again, and
the refrigerant is subsequently liquified in order to make it
available for renewed evaporation. Thus, the heat rejected by the
engine is used to heat the sorbent. The system includes methanol as
refrigerant and activated charcoal as sorbent. However, this
absorption refrigeration system is configured for the air
conditioning of a vehicle, and appears to be inappropriate for the
cooling of individual components of a supercharged engine,
particularly that of an agricultural tractor. Furthermore, other
potential sources of heat, such as the engine exhaust, cannot be
utilized for the high temperatures required for the desorption in
the adsorption refrigeration machine disclosed by published German
patent application DE 199 27 879 A1 because extensive
design-engineering changes would be required.
SUMMARY
[0005] Accordingly, an object of this invention is to provide a
cooling system which reduces the thermal load on a conventional
main cooling system.
[0006] A further object of the invention is to provide such a
cooling system for an engine block or a charge air cooling
system.
[0007] These and other objects are achieved by the present
invention, wherein a cooling system includes a known sorption
cooling system. The sorption cooling system includes an evaporator
for evaporating a refrigerant, a sorption chamber containing an
absorbent which absorbs the evaporated refrigerant, a desorption
chamber for desorption of the refrigerant from the absorbent and a
condenser for condensing the refrigerant. To supply the heat
required for the desorption, a first exhaust gas stream of the
engine is communicated to the desorption chamber. The evaporator
provides additional cooling of the coolant of the main cooling
system, and/or cools a second exhaust gas stream from the engine.
Combining a conventional main cooling system with a sorption
cooling system decreases the load on the main cooling system and
the evaporator reduces heat rejection. The evaporator is positioned
at the cylinder head and directly cools the cylinder head, so that
the heat rejected there does not fully load the main cooling
system.
[0008] The heat removed by the sorption cooling system or the heat
removed by the evaporator can be delivered to the surroundings at a
considerably higher temperature level by the condensation of the
refrigerant. Thus, higher temperature differences to the
surroundings can be realized and hence a more compact configuration
of coolers is possible.
[0009] The evaporator can be positioned to extract heat from other
components, such as, for example, the engine itself, parts of the
mechanical power transmission, components of the power electronic
system, electrical machines, the vehicle cab, the charge air, a
recirculated exhaust gas stream or any other components that can be
cooled contained in or on the vehicle. Moreover, this cooling
system can be used to cool fluids such as engine oil or gearbox
oil.
[0010] The sorption cooling system extracts heat from the
conventional main cooling system, at a cost in thermal output.
Preferably, thermal output supplies the power for the sorption
cooling system. Thereby in a sorption cooling system a "thermal
compressor" is realized in contrast to the mechanically driven
compressors which are widely used in refrigeration machines and in
air conditioners.
[0011] The thermal output required to drive the sorption cooling
system is extracted from the vehicle, preferably from the exhaust
gas of the engine. But, other sources of thermal energy are also
conceivable. For example, the rejected heat of the engine or the
engine cooling water or any other available source of heat in the
vehicle could be used.
[0012] The process where a material is taken up selectively by
another material is known as absorption or adsorption. When the
particular process is unknown, the process is known as sorption.
The sorbing material is referred to as a sorbent. The material that
is sorbed is the sorbate. "Desorption" is the regeneration or the
separation of the material that was sorbed.
[0013] Absorption is the process in which gases are taken up by
fluids or solids, wherein the dissolved gas component is the
absorbent and the fluid (solvent) is the absorbate. Desorption is
the reverse of the absorption, wherein gas is driven off at
increased temperature and/or reduced pressure and the solvent is
regenerated.
[0014] Adsorption is the deposition of gases and dissolved
materials (adsorbate) on the surface of solids (adsorbent), for
example, the binding of steam as adsorbate to an activated charcoal
adsorbent. Adsorption takes place not only on the outer surface of
the absorbent, but also in its pores, as long as these are
accessible to the absorbate. During the adsorption process, the
heat of adsorption is liberated. The heat of adsorption is
approximately of the magnitude of the heat of condensation.
Important adsorbents are activated charcoal, silica jell, aluminum
oxide or even fullers earth.
[0015] In general, desorption is the reverse of the absorption or
adsorption process at higher temperatures or lower pressures where
absorbed or the adsorbed material is regenerated.
[0016] An absorption cooling system operates with a liquid solvent
as sorbent or absorbent, and an adsorption cooling system operates
with a solid sorbent. An absorption cooling system will include an
absorbent and an absorbate, such as, for example, a solvent and a
refrigerant, where the refrigerant is absorbed by the solvent and
is again separated from it in the desorption process. For example,
lithium bromide absorbs water, and water absorbs ammonia. The
material absorbed functions as a refrigerant (absorbate), while the
other material functions as a solvent (absorbent). The refrigerant
and the solvent are together characterized as an operating pair.
The solution of the materials is heated in order to separated them
from each other again in the desorption chamber (boiler or
separator). The refrigerant evaporates first because of its lower
evaporation temperature. The evaporated refrigerant is freed from
the rest of the solvent with which it had been evaporated by means
of a liquid separator. Then, the refrigerant is cooled in the
condenser (liquefier) and thereby liquified. The pressure of the
refrigerant is reduced to an evaporation pressure corresponding to
a predetermined temperature by a control valve. In the evaporator
the refrigerant is evaporated by absorbing heat, and the heat
absorbed provides the cooling effect. Next, the refrigerant vapor
is conducted into the sorption chamber. After the separation from
the refrigerant (absorbent) or after the desorption, the pressure
of the solvent (absorbate) is reduced by a valve to the sorption
chamber pressure, cooled and conducted to the sorption chamber.
Thereby, the solvent takes up the refrigerant vapor in the sorption
chamber. A solvent pump conducts the enriched solution back to the
ejector, the circulation is thereby closed. The entire solvent
circulation operates as a "thermal compressor", and functions as a
compressor of a compression refrigeration machine. As noted
initially, the amount of heat required for the evaporation QO and
the amount of heat required for the desorption QH can be derived
from differing vehicle components, so that the amount of heat that
is to be rejected by the main cooling system is reduced, and that
the amount of heat required for the evaporation QO is derived from
the main cooling system. ***The system operates more effectively
with higher temperature of the cooling water of the main cooling
system. The tendency to raise the pressure level in the main
cooling circuit in order to attain correspondingly higher allowable
temperatures therefore promotes the possibilities of the absorption
cooling systems. The driving temperatures for the ejection lie
between 90.degree. C. and 140.degree. C., where the medium or the
components to be cooled can assume similar temperatures as with the
cooling with an adsorption cooling system.
[0017] An adsorption cooling system includes an adsorption chamber
filled with a sorbent or an adsorbent, and a desorption chamber
filled with an adsorbent, a condenser and an evaporator. As in the
case of an absorption cooling system, in an adsorption cooling
system various pairs of materials are possible. The adsorbent may
be for example, silica gel, and the refrigerant may be adsorbate
water. It is also known to use activated charcoal as adsorbent and
methanol as adsorbate. The process is discontinuous and closed.
During a cycle the following processes occur: The water (adsorbate)
adhering to the silica gel (adsorbent) is driven out in the
desorption chamber with the supply of an amount of heat QH by a
heated water circulation associated with the desorption chamber.
The water is liquified in the condenser and heat is carried away by
the cooling water circuit associated with the condenser. The
condensate is sprayed into the condenser and evaporated under
strong negative pressure. An amount of heat QO is extracted from
the surroundings or from a component that is to be cooled. The
water vapor is adsorbed in the adsorption chamber and the resulting
heat of adsorption is conducted to a cooling water circuit
associated with the adsorption chamber. By simply reversing the
heating and cooling water circuits of the desorption or the
adsorption chamber between the two chambers the functions of
desorption and adsorption are interchanged at the end of a cycle
and the process is started anew.
[0018] The desorption of the adhering water and the generation of
pressure for the condensation occurs at low temperatures of
60.degree. C.-70.degree. C., so that this technology can be applied
at lower temperatures than with an absorption cooling system.
[0019] Such a sorption cooling system can be driven "at no cost" by
heat sources available on the vehicle, for example, the exhaust
gas, instead of mechanical power required by compressors.
Furthermore, the cooling capacities of a conventional cooling
system can be reduced, and the amount of heat that must be removed
in a water-to-air heat exchanger from the engine is reduced,
thereby reducing the load on the main cooling system, and it is
possible to remove heat at a higher temperature than in a
conventional cooling system. Moreover, the energy required for
cooling of further components can be minimized and fuel consumption
can be reduced. In addition, it is possible to use environmentally
benign refrigerants. Furthermore, if an air conditioning
installation exists, mechanical or electrical compressor drive
units can be omitted or their size reduced. Furthermore, various
fluids and tractor components can be cooled to temperatures below
the temperature of the surroundings. In contrast to a cooling
system with a compressor, fewer moving parts are required, and
hence fewer components are subject to wear. Beyond that, the
exhaust back pressure is not increased with the heat exchanger
outside at the exhaust pipe of the vehicle.
[0020] In a preferred embodiment of the invention, a first exhaust
gas stream of the engine is an exhaust gas stream of an exhaust gas
recirculation system, so that the heat required for desorption is
extracted from the vehicle exhaust gas recirculation system. This
advantageously cools the recirculated exhaust gas, and when the
recirculated exhaust gas reaches the engine combustion chamber it
results in a reduced heating of the charged air and thereby an
improved charging or improved emission values can be obtained
during the combustion.
[0021] In another embodiment, the first exhaust gas stream is
branched off from the main exhaust gas stream delivered to the
environment. Thus, the heat of an exhaust gas stream can be used to
drive the desorption chamber, thereby improving the total energy
balance of the vehicle.
[0022] In a further embodiment, the main cooling system is a charge
air cooling system and that the evaporator of the sorption cooling
system is used for additional cooling of the charge air cooling
system. Thus, the charge air cooling system can be configured more
efficiently, or the cooling performance for the charge air can be
improved so that an increased amount of charge air reaches the
engine combustion chamber. This improves emission values.
[0023] In a further embodiment, the main cooling system is an
engine block cooling system and that the evaporator of the sorption
cooling system is used for additional cooling of the engine block
cooling system. This reduces the load on the main engine cooling
system. This can be utilized either to reduce the required cooler
volume or, if necessary, to increase the entire cooling
capacity.
[0024] In a further embodiment, the main cooling system is an air
conditioner cooling system and that the evaporator of the sorption
cooling system is used for additional cooling of the cab air flow.
This permits a reduced size of the air conditioner compressor, and
less mechanical energy needs to be drained away from the vehicle.
This, in turn, leads to an improved total energy balance of the
vehicle and hence a lower fuel consumption.
[0025] In a further embodiment, the second exhaust gas stream is an
exhaust gas stream of an exhaust gas recirculation system, where
the evaporator of the sorption cooling system cools the exhaust gas
in the exhaust gas recirculation system. Thus, the heat of the
exhaust gas is used to drive the desorption chamber, thus improving
the total energy balance of the vehicle. Another advantage is that
the recirculated exhaust gas is cooled, and upon the recirculation
of the exhaust gas into the engine combustion chamber, heating of
the charge air is reduced, thereby improving air charge or
emissions during the combustion.
[0026] Preferably, the condenser is connected with a cooler, which
carries away the heat liberated in the condenser. The amount of
heat generated by condensing the refrigerant (sorbent) can thereby
be efficiently delivered to the surroundings, and heat is
transferred at a higher temperature.
[0027] In another embodiment of the invention, the sorption chamber
is connected with a cooler which carries away the heat liberated in
the sorption chamber. Thereby the amount of heat generated by the
sorption of the refrigerant (sorbent) can be efficiently delivered
to the surroundings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a schematic block diagram of a cooling system
according to the invention with a sorption cooling system to reduce
the load on a charge air cooling circuit;
[0029] FIG. 2 is a schematic block diagram of a sorption cooling
system which reduces the load on the charge air cooling system;
[0030] FIG. 3 is a schematic block diagram of a cooling system
according to the invention with a sorption cooling system which
reduces the load on the cooling circuit for an internal combustion
engine;
[0031] FIG. 4 is a schematic block diagram of a cooling system
according to the invention with a sorption cooling system which
cools an exhaust gas recirculation system; and
[0032] FIG. 5 is a schematic block diagram of a cooling system
according to the invention with a sorption cooling system which
reduces the load on a cab air cooling system.
DETAILED DESCRIPTION
[0033] FIG. 1 shows a cooling system 10 for an internal combustion
engine 12 with a charge air system 14, a charge air cooling system
16, an engine cooling system 18, an exhaust gas recirculation
system 20, and a sorption cooling system 22. The sorption cooling
system 22 is applied in order to reduce the load on the charge air
cooling system 16.
[0034] The engine 12 includes an intake system 24 which is supplied
with super charged and cooled air 26 and recirculated exhaust gas
28. The recirculated exhaust gas 28 is withdrawn from the exhaust
gas stream 30 flowing out of the engine 12 and conducted to the
intake system 24 of the engine 12. By means of the exhaust gas
recirculation system 20, the amount of the exhaust gas delivered to
the surroundings can be reduced and the emissions reduced.
[0035] In order to cool the engine 12, the engine cooling system 18
is connected to the engine 12 over coolant lines 32. The coolant
lines 32 are connected with an engine cooler 34, so that a coolant
(not shown) in the coolant lines 32 circulates between the engine
cooler 34 and the engine 12 and carries away heat generated in the
engine 12 to the engine cooler 34.
[0036] The charge air system 14 is used, among other uses, to
compress the intake air taken in from the surroundings so that an
increased amount of air flows into the intake system 24 of the
engine 12, resulting in improved combustion of the fuel and thereby
reducing emissions in the exhaust gas. The charge air system 14
includes an air filter 36 that filters intake air taken in from the
surroundings and from which the filtered intake air is conducted
into a turbo-supercharger 38. The turbo-supercharger 38 includes a
drive side (not shown) and a compressor side (not shown). The drive
side of the turbo-supercharger 38 is driven by a drive exhaust gas
stream 40, where the drive exhaust gas stream 40 is also branched
off from the exhaust gas stream 30. The intake air from the air
filter 36 is compressed in the compressor side of the
turbo-supercharger 38. This compression increases the density of
the intake air and increases the heat of the intake air. This heat,
in turn, has a negative effect on the combustion of the fuel, for
which reason the charge air system 14 as a rule is also connected
to a charge air cooling system 16. The charge air cooling system 16
includes a charge air cooler 42 which is connected over charge air
coolant lines 44 with a heat exchanger 46. The heat exchanger 46 is
positioned between the turbo-supercharger 38 and the intake system
24 so that a coolant (not shown) in the charge air coolant lines 44
circulates between the heat exchanger 46 and the charge air cooler
42 and cools a flow of heat coming from the compressed charge air
on the charge air cooler 42.
[0037] According to FIG. 1, the sorption cooling system 22 includes
a desorption chamber 48 arranged in the recirculated exhaust gas
stream 28, a condenser 50 associated with the desorption chamber
48, a condenser cooler 54 connected by condenser coolant lines 52
for removing the heat liberated in the condenser, an evaporator 56
arranged at the charge air coolant lines 44, and a sorption chamber
58 with a sorption chamber cooler 62 connected by sorption chamber
coolant lines 60 for removing the heat liberated in the sorption
chamber 58.
[0038] At least some components similar to those shown in FIG. 1
and with the same reference numbers are also included in FIGS.
2-5.
[0039] FIG. 2 illustrates the principle of operation of a cooling
system wherein the sorption cooling system 22 reduces the load on
the charge air cooling system 16. Several components shown in FIGS.
1 and 3-5 are omitted from FIG. 2 to better illustrate the
operation of the cooling system 10.
[0040] The sorption cooling system 22 of FIG. 2 includes a solvent
circulation circuit 64 and a refrigerant circuit 66. The solvent
circuit 64 includes the desorption chamber 48 driven by the
recirculated exhaust gas stream 28, a first control valve 68, the
sorption chamber 58 and a solvent pump 70. The refrigerant circuit
66 includes the desorption chamber 48 driven by the recirculated
exhaust gas stream 28, the condenser 50, a second control valve 72,
the evaporator 56 and the sorption chamber 58. Furthermore, the
condenser 50 and the sorption chamber 48 are each connected with a
cooler 54, 62 which delivers the thermal output to be carried away
from the condenser 50 or the sorption chamber 58 to the
surroundings. To reduce the load on the charge air cooling system
16, the evaporator 56 of the sorption cooling system 22 is
integrated into the charge air cooling circuit 74 of the charge air
cooling system 16.
[0041] The cooling system 10 includes a two-material mixture (not
shown) in the solvent circuit 64, which is located in the supply
line 76 directed at the desorption chamber 48. The two-part mixture
in the supply line 76 consists of a solvent (not shown) which is
mixed with a refrigerant (not shown) for cooling and circulating in
the refrigerant circuit 66 or which has sorbed this in the sorption
chamber 58. The two-part mixture is conveyed by the solvent pump 70
into the desorption chamber 48. In the desorption chamber 48 the
two-part mixture is heated by the heat from the recirculated
exhaust gas stream 28. The refrigerant taken up by the solvent has
a lower evaporation temperature than the solvent, so that the
refrigerant evaporates before the solvent evaporates. This causes
the desorption of the refrigerant out of the solvent. The
refrigerant vapor desorbed in the desorption chamber 48 or driven
out, flows through a first connecting line 78 into the condenser
50. The refrigerant vapor is liquified in the condenser 50 where
the thermal flow is carried away at a higher temperature level
compared to a conventional cooling system and with a higher
temperature difference between the condenser cooler 54 and
condenser 50. The condensed or cooled refrigerant flows into the
evaporator 56 over a supply line 80 controlled by the second
control valve 72. The refrigerant is evaporated in the evaporator
while taking up heat from the charge air cooling system 16. Heat is
thereby effectively withdrawn from the charge air cooling system 16
by the evaporator 56 or by the heat taken up by the refrigerant.
Thus the cooling system 10 reduces the load on the charge air
cooling system 16, thereby either improves the cooling capacity of
the charge air cooling system 16 or reduces the dimensions of the
charge air cooling system 16.
[0042] The refrigerant vapor flowing out of the evaporator 56 flows
into the sorption chamber 58. The solvent circulating in the
solvent circuit flows over the first control valve 68 into the
sorption chamber 58 and is available to take up the refrigerant
vapor or for the sorption of the refrigerant vapor. In the sorption
chamber the refrigerant vapor is taken up by the solvent or it is
sorbed, thereby generating heat of solution that is carried away
over the sorption cooler 62. The refrigerant flowing out of the
evaporator that has not been evaporated or is still liquid is
conducted over a further supply line 82 over the desorption chamber
48 and driven into the condenser 50. Thereby, both circuits are
closed, that is, the refrigerant circuit 66 and the solvent circuit
64 are closed. The improved cooling performance relative to the
charge air on the basis of lower combustion temperatures in the
intake system 24 of the engine 12 improves emissions.
[0043] The cooling system 10 and the sorption cooling system 22 of
FIG. 2 can also reduce the load on other main cooling systems or
even for the cooling of the recirculated exhaust gas 48. This is
shown in FIGS. 3-5.
[0044] In a second embodiment shown in FIG. 3, the evaporator 56 is
integrated into the engine cooling system 18. In this embodiment
the heat removal of the engine cooling system 18 or the reduction
of the load on the engine cooling system 18 is performed in the
same way by the evaporator 56, as is the case with the reduction of
the load on the charge air cooling system 16 of FIG. 1 or 2. In the
FIG. 3 embodiment a separate exhaust gas stream 84 is branched off
from the main exhaust gas stream 30 in order to drive the
desorption chamber. The embodiment shown in FIGS. 1 and 2 is also
conceivable, in which the desorption chamber 48 is driven by the
recirculated exhaust gas stream 28 as is shown in FIG. 3 with a
desorption chamber 48' driven by a recirculated exhaust gas stream.
Furthermore, an embodiment is conceivable even without the charge
air cooling system 16 and without the exhaust gas recirculation
system 20. Similar to the charge air cooling system 16 of FIGS. 1
and 2, the FIG. 3 embodiment reduces the load on the engine cooling
system 18, either by increasing the cooling capacity of the engine
cooling system 18 or by reducing the size of the engine cooling
system 18.
[0045] In the further embodiment of FIG. 4, the sorption cooling
system 10 can be used to cool the recirculated exhaust gas stream
28, to improve combustion performance of the engine 12 and thereby
reduce the load on the engine cooling system 18 and the charge air
cooling system 16, or improve the entire energy balance of the
engine 12. If the recirculated exhaust gas stream 28 is conducted
without any cooling into the intake system 24 of the engine 12, the
charge air that was previously cooled by the charge air cooling
system 16 is heated. This worsens emission performance of the
engine 12. The evaporator 56 of FIG. 4 is integrated into the
exhaust gas recirculation system 20 and heat is withdrawn from the
recirculated exhaust gas stream 28 during the evaporation of the
refrigerant in the evaporator 56. According to FIG. 4, as is also
shown in FIG. 3, the separated exhaust gas stream 84 is also used
to drive the desorption chamber 48.
[0046] In a further embodiment shown in FIG. 5, the evaporator 56
is integrated into an air conditioning cooling system (not shown).
In this way a cab air stream 86 pre-cooled by a conventional,
mechanically driven compressor (not shown), can be post-cooled or,
in a reverse arrangement, also pre-cooled by the evaporator 56 and
post-cooled by the compressor. The other components of the cooling
system of FIG. 5 can be arranged similarly to the embodiments of
FIGS. 1-4. The reduced load on the air conditioning system by the
desorption cooling system leads to smaller mechanically driven
compressor and thereby reduces energy requirements for the air
conditioning system.
[0047] The sorption cooling systems of FIGS. 1-5 can also be
combined with each other. For example, several evaporators can be
arranged in a parallel or a series circuit and used to cool the
charge air, the recirculated exhaust gas, 58, the engine cooling
water and/or the cab air stream 86.
[0048] While the present invention has been described in
conjunction with a specific embodiment, it is understood that many
alternatives, modifications and variations will be apparent to
those skilled in the art in light of the foregoing description.
Accordingly, this invention is intended to embrace all such
alternatives, modifications and variations which fall within the
spirit and scope of the appended claims.
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