U.S. patent application number 11/256916 was filed with the patent office on 2007-04-26 for heat exchanger method and apparatus.
Invention is credited to Gregory J. Saele.
Application Number | 20070089716 11/256916 |
Document ID | / |
Family ID | 37984189 |
Filed Date | 2007-04-26 |
United States Patent
Application |
20070089716 |
Kind Code |
A1 |
Saele; Gregory J. |
April 26, 2007 |
HEAT EXCHANGER METHOD AND APPARATUS
Abstract
A method for an internal combustion engine includes the steps of
collecting exhaust gas in a volume (502) and flowing exhaust gas
out of the volume in a first and a second portions (504). The first
portion forms a tailpipe gas stream (506), and the second portion
forms an EGR gas stream (508). The tailpipe gas stream goes through
a turbine (510), and is heated in a heat exchanger (512). The heat
exchanger transfers thermal energy out of the EGR gas stream (516)
to heat the tailpipe gas stream. The EGR gas stream is recirculated
into an intake of the internal combustion engine (518).
Inventors: |
Saele; Gregory J.; (Itasca,
IL) |
Correspondence
Address: |
INTERNATIONAL ENGINE INTELLECTUAL PROPERTY COMPANY
4201 WINFIELD ROAD
P.O. BOX 1488
WARRENVILLE
IL
60555
US
|
Family ID: |
37984189 |
Appl. No.: |
11/256916 |
Filed: |
October 24, 2005 |
Current U.S.
Class: |
123/568.12 ;
60/320; 60/605.2 |
Current CPC
Class: |
F02B 37/00 20130101;
F01N 3/0205 20130101; F02M 26/15 20160201; F02M 26/24 20160201;
F01N 2240/02 20130101; F02M 26/05 20160201; F28D 7/106 20130101;
F28F 2240/00 20130101; F02M 26/32 20160201; F02M 26/25 20160201;
F02B 29/0406 20130101; Y02T 10/12 20130101 |
Class at
Publication: |
123/568.12 ;
060/320; 060/605.2 |
International
Class: |
F02M 25/07 20060101
F02M025/07; F02B 47/08 20060101 F02B047/08; F01N 5/02 20060101
F01N005/02; F02B 33/44 20060101 F02B033/44 |
Claims
1. A method for an internal combustion engine comprising the steps
of: collecting exhaust gas in a volume; flowing exhaust gas out of
the volume in a first and a second portions, wherein the first
portion forms a tailpipe gas stream, and wherein the second portion
forms an exhaust gas recirculation (EGR) gas stream; passing the
tailpipe gas stream through a turbine; transferring thermal energy
from the EGR gas stream in a heat exchanger, wherein the EGR gas
stream is cooled in the heat exchanger; heating the tailpipe gas
stream in the heat exchanger with the extracted thermal energy; and
recirculating the EGR gas stream into an intake of the internal
combustion engine.
2. The method of claim 1, wherein volume is an exhaust manifold of
the internal combustion engine, and wherein the EGR gas stream
flows from the exhaust manifold upstream of the turbine.
3. The method of claim 1, wherein the tailpipe gas stream is
exhaust gas flowing from an outlet of the turbine.
4. The method of claim 1 wherein the heat exchanger is an
air-to-air heat exchanger.
5. The method of claim 1, further comprising the step of passing
the tailpipe gas stream through at least one after-treatment
component.
6. The method of claim 1, wherein the at least one after-treatment
component is a diesel particulate filter.
7. An apparatus comprising: an engine having an intake manifold and
an exhaust manifold; a turbine in fluid communication with the
exhaust manifold; a heat exchanger having a hot gas inlet, a cold
gas inlet, a warm gas outlet, and a cooled gas outlet; wherein hot
gas inlet is in direct fluid communication with the exhaust
manifold and the cooled gas outlet, wherein the cold gas inlet is
in direct fluid communication with the turbine and the warm gas
outlet; and wherein the cooled gas outlet is in direct fluid
communication with the intake manifold.
8. The apparatus of claim 7, further comprising an exhaust gas
recirculation valve in fluid communication with the cooled gas
outlet.
9. The apparatus of claim 7, further comprising an exhaust gas
recirculation cooler in fluid communication with the EGR valve.
10. The apparatus of claim 7, further comprising an after-treatment
component in fluid communication with the warm gas outlet, wherein
the at least one after-treatment component is a diesel particulate
filter.
11. The apparatus of claim 7, wherein the heat exchanger is an
air-to-air heat exchanger.
12. The apparatus of claim 11, wherein the air-to-air heat
exchanger includes an inner tube and an outer tube, wherein the
inner tube and the outer tube are concentric, and wherein the
air-to-air heat exchanger is disposed at an outlet of the
turbine.
13. The apparatus of claim 12, wherein a tailpipe exhaust stream
flows in the inner tube, and wherein an exhaust gas recirculation
exhaust stream flows in a volume formed between the inner tube and
outer tube.
14-17. (canceled)
Description
FIELD OF THE INVENTION
[0001] This invention relates to internal combustion engines,
including but not limited to engines having exhaust gas heat
exchangers.
BACKGROUND OF THE INVENTION
[0002] Internal combustion engines generate heat during operation
that is released into the environment through exhaust gas
emissions. Modern emission controls systems may utilize energy, in
the form of heat from the exhaust gas, to operate various
components, for example, Diesel Particulate Filters (DPF). In other
cases, heat may be undesirable and removed by use of other
components and systems.
[0003] One example of a case where additional heat is desirable for
the operation of an engine is the operation of a DPF, which depends
on a reaction that occurs internally to the DPF and burns
particulates that have accumulated therein. Some engines
incorporate thermal shielding on their exhaust systems to contain
exhaust heat and make it available for emissions components. Heat
makes the regeneration of the DPF more efficient. One example of a
case where removal of heat is required for proper operation of the
engine is in an exhaust gas recirculation (EGR) system, which
recirculates cooled exhaust gas into an intake of the engine. EGR
systems typically use exhaust gas coolers to remove heat from an
exhaust gas stream during recirculation.
[0004] Even though heat input may be desirable for some engine
systems, heat removed from other systems that is typically rejected
back to the engine is undesirable. Heat rejected and/or generated
internally to the engine is removed from the engine by a cooling
system. Typical cooling systems promote efficient operation of the
engine and protect heat sensitive systems. Thermally conductive
fluids, that include for instance oil or engine coolant, carry heat
collected from within the engine and/or engine components to a
radiator, which then expels the heat to the environment.
[0005] Accordingly, there is a need for heat management in an
engine that reduces undesirable internal heat load to the
engine.
SUMMARY OF THE INVENTION
[0006] A method for an internal combustion engine includes the step
of collecting exhaust gas in a volume. Exhaust gas flows out of the
volume in a first portion and a second portion. The first portion
forms a tailpipe gas stream and the second portion forms an exhaust
gas recirculation (EGR) gas stream. The tailpipe gas stream passes
through a turbine. Thermal energy from the EGR gas stream is
extracted with a heat exchanger and the EGR gas stream is cooled.
The tailpipe gas stream is heated in the heat exchanger with the
extracted thermal energy and the EGR gas stream is recirculated
into an intake of the internal combustion engine.
[0007] An apparatus includes an engine having a plurality of
cylinders in fluid communication with an intake manifold and an
exhaust manifold. A turbine is in fluid communication with a
tailpipe system and the exhaust manifold. An air-to-air heat
exchanger has a hot gas inlet, a cold gas inlet, a warm gas outlet,
and a cooled gas outlet. The hot gas inlet is in direct fluid
communication with the exhaust manifold and the cooled gas outlet.
The cold gas inlet is in direct fluid communication with the
turbine and the warm gas outlet. At least one tailpipe component is
in fluid communication with the hot gas outlet.
[0008] An air-to-air heat exchanger includes an inner tube and an
outer tube placed around the inner tube. The inner tube and the
outer tube are concentric. A plurality of tabs is connected between
the inner tube and the outer tube. A first gas stream flows in a
first direction in an inner volume of the inner tube. A second
volume is formed between the inner tube and the outer tube, and a
second gas stream flows in a second direction in the second volume.
The first direction and the second direction are advantageously
opposite.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a block diagram of a typical engine.
[0010] FIG. 2 is a block diagram of an engine having an air-to-air
heat exchanger in accordance with the invention.
[0011] FIG. 3 is a perspective view of a section of an air-to-air
heat exchanger that includes two concentric tubes in accordance
with the invention.
[0012] FIG. 4 is a section view of the air-to-air heat exchanger of
FIG. 3.
[0013] FIG. 5 is a flowchart for a method for effectively managing
and recuperating heat in an internal combustion engine
DESCRIPTION OF A PREFERRED EMBODIMENT
[0014] The following describes an apparatus for and method of
reducing undesirable heat load for a cooling system of an internal
combustion engine. A typical turbocharged diesel engine system 100
having cooled EGR is shown in FIG. 1. Fresh air enters a compressor
101 of an engine 107. An outlet of the compressor 101 is connected
to a charge air cooler 103. An outlet of the charge air cooler 103
is connected to an intake manifold 105 of an engine 107. Compressed
air enters the intake manifold 105 of the engine 107 where it is
mixed with fuel. The mixture of air and fuel is compressed in a
combustion cylinder and combusts releasing work and heat. Heat
released from the combustion of fuel and air is removed from the
engine 107 in two ways. First, fluids such as oil and/or
water-based coolants are circulated through the engine 107, in
direct contact with engine components.
[0015] As engine components heat up, fluid circulating through the
engine 107 is heated by conduction and/or convection. The heated
fluid carries with it heat removed from the engine components. The
heated fluid is taken to a radiator 123 through a radiator coolant
supply passage 125. Heat is released to the environment by the
radiator 123, and cooled fluid returns to the engine 107 through a
radiator coolant return passage 127. In addition to the radiator
123, a second avenue for releasing heat from the engine is heat
that is carried away from the engine 107 by exhaust gas exiting the
engine 107 when combustion is complete, through an exhaust manifold
109.
[0016] A portion of the exhaust gas in the exhaust manifold 109 is
recirculated into the intake manifold 105 of the engine 107 by
passing through an EGR valve 119 and an EGR cooler 121. The EGR
cooler 121 typically is an air-to-water cooler. Coolant from the
engine 107 may enter the EGR cooler 121 through a coolant feed
passage 129. Coolant from the coolant feed passage 129 passes
through the cooler and collects heat from exhaust gas passing
through the cooler that comes from the exhaust manifold 109. The
exhaust gas is cooled and the coolant is heated. Heated coolant
returns to the engine 107 through a coolant return passage 131. The
coolant entering the engine 107 through the return passage 131
mixes with warm coolant coming from internal components of the
engine 107, and is eventually routed to the radiator 123 where heat
from the engine 107 and the EGR cooler 121 is expelled to the
environment.
[0017] Another portion of the exhaust gas from the exhaust manifold
109 is routed to a turbine 111. The turbine 111 converts a portion
of the heat and pressure of the exhaust gas into work to operate
the compressor 101, and cooled exhaust gas at a lower pressure is
expelled from the turbine 111 to the environment, or alternatively
into after-treatment components, for example, a DPF 115.
[0018] The DPF 115 collects combustion byproducts from the exhaust
gas and intermittently burns the byproducts through a process
called regeneration. The efficiency of the regeneration process
depends on the heat input to the DPF 115 from the exhaust gas.
Increased thermal energy passing through the DPF 115 may lead to
more efficient regeneration.
[0019] One disadvantage of the system shown in FIG. 1 is
sub-optimal use of heat or thermal energy. Heat removed from the
recirculated exhaust gas in the EGR cooler 121 is transferred to
the engine cooling system and is subsequently released to the
environment thus increasing a thermal load requirement for the
cooling system. The system shown in FIG. 2 solves this and other
problems.
[0020] An engine system 200 includes many common components as the
engine system 100 shown in FIG. 1, with the exception of a heat
exchanger 211. The common components are not described in detail
for the sake of brevity. The heat exchanger 211 has a hot gas inlet
213, a warm gas outlet 215, a cold gas inlet 217, and a cooled gas
outlet 219. The cold gas inlet 217 is fluidly connected to the warm
gas outlet 215 to form a tailpipe gas stream 223, and the hot gas
inlet 213 is fluidly connected to the cooled gas outlet 219 to form
an EGR exhaust gas stream 221. Exhaust gas from the exhaust
manifold 109 enters the heat exchanger 211 from the hot gas inlet
213, and exits through the cooled gas outlet 219. Exhaust gas from
the exhaust manifold 109 also enters the turbine 111.
[0021] Exhaust gas exiting the turbine 111 enters the heat
exchanger 211 from the cold gas inlet 217, and exits from the warm
gas outlet 215 from where it is expelled to the environment. If
after-treatment components are present, for example a DPF 250, or
other components, the exhaust gas from the warm gas outlet 215 may
pass through those components before being expelled to the
environment. A temperature difference that exists between the EGR
gas stream 221 and the tailpipe exhaust gas stream 223, before the
two streams 221 and 223 enter the heat exchanger 211, causes heat
to be transferred from the EGR gas stream 211 to the tailpipe gas
stream 223 in the heat exchanger 211. The heat exchanger 211
effectively cools the EGR gas stream 221 and warms up the tailpipe
gas stream 223.
[0022] Heat transfer occurring in the heat exchanger 211 is
advantageous. A desired amount of heat removed from the EGR stream
221 may be determined by consideration of various factors, for
example, the emissions requirements of the engine 107, or the use
and capacity of an optional air to water EGR cooler 221. With a
cooling effect applied to the EGR exhaust gas stream 221 in the
heat exchanger 211, use of the air to water EGR cooler 225 and all
design, manufacturing and development costs associated therewith
may advantageously be avoided. A decision whether the optional air
to water EGR cooler 225 is required may be determined by the
ability to achieve a desired temperature of recirculated exhaust
gas being recirculated. Regardless of use of the cooler 225, the
ability to remove heat from the EGR stream 221, and to add heat to
the tailpipe gas stream 223, can be advantageous.
[0023] First, the heat removed from the EGR gas stream 221 would
have otherwise been expelled to the environment by being
transferred to a cooling system and expelled through a radiator.
With an implementation of the air-to-air heat exchanger 211 the
heat removed from the EGR gas stream 221 is conserved and can be
used for optimization of the operation of after-treatment
components like the DPF 115. Second, there is a reduced heat
transfer requirement on the EGR cooler 225, when used, because heat
is removed from the EGR gas stream 221 upstream of the cooler 225.
This reduced heat transfer requirement allows for use of a smaller
and less costly EGR cooler 121. The reduced heat load on the EGR
cooler 225 is also advantageous for the cooling system of the
engine 107 because the size and cost of a vehicle's radiator may be
reduced, and various attributes of the cooling system, such as a
coolant pump (not shown) and passages, including the passages 125
and 127, may be downsized. Moreover, additional reductions of fan
size and frequency of fan engagement may be implemented that may
improve fuel economy by reducing parasitic losses.
[0024] Use of the EGR cooler 225 is optional. A coolant supply
passage 227 and a coolant return passage 229 for the cooler 225 are
also optional. If efficiency of the heat exchanger 211 is adequate
to meet emissions requirements of the engine, there may be no need
for a secondary cooler such as the air-to-water EGR cooler 225.
Moreover, the heat exchanger 225 may be implemented in a different
engine configuration that includes more than one turbine or
compressor (not shown).
[0025] One possible implementation for an air-to-air heat exchanger
300 is shown in FIG. 3. The air-to-air heat exchanger 300 is
configured to operate as a tube that is part of an exhaust system
of an engine installed in a vehicle. The heat exchanger 300 may
advantageously be positioned in a vehicle downstream of a turbine,
as shown in the embodiment of FIG. 2, and form part of what is
known in the art as a "down-pipe", denoting a tube connecting an
outlet of a turbine with after-treatment and/or exhaust and/or a
tailpipe of a vehicle.
[0026] The heat exchanger 300 includes an inner tube 302 contained
in an outer tube 304. The tubes 302 and 304 may be concentric and
may be thin walled steel tubes. The tubes may be connected with a
plurality of tabs 306. One such tab 306 is shown in a partial
cut-away section A-A, shown in FIG. 4. Each tab 306 may be
cold-welded in position between the tubes 302 and 304, or may
alternatively be fabricated between two plates that are formed into
a tubular shape, but other methods for manufacture may be used. In
the embodiment presented, a set of eight tabs 306 are used but
another number of tabs 306 may be used to connect the tubes 302 and
304.
[0027] The inner tube forms an inner passage 308. The inner passage
308 is a volume enclosed within the inner tube 302 and is
advantageously fluidly isolated from an outer passage 310 formed
internally to the outer tube 304 and externally to the inner tube
302. In one embodiment, the heat exchanger 300 may be used as the
air-to-air heat exchanger 211 shown in FIG. 2. The inner passage
308 may be used for routing of the tailpipe gas stream 223
traveling in a direction 312 denoted by the solid line arrows. The
outer passage 310 may be used for routing of the EGR gas stream
221, advantageously insulating the tailpipe gas stream from the
ambient environment to prevent heat loss. The EGR gas stream 221
travels in a direction 314 denoted by the dashed-line arrows,
opposite of the direction 312 of travel for the after-treatment
stream 223.
[0028] The directions 312 and 314 are advantageously opposite to
promote more heat transfer between the two gas streams 221 and 223.
Moreover, the tabs 306 that connect the tubes 302 and 304 also may
be used as fins to promote the transfer of heat between the two
streams 221 and 223, although additional fins may be added to the
inner passage 308 and/or other fin configurations may be used in
addition to or instead of the tabs 306. The tabs 306 are arranged
along a plurality of radial directions with respect to a common
center-point with the tubes 302 and 304. Fins, additional tubes,
and other common heat exchanger design elements may be added to
improve effectiveness of heat transfer.
[0029] A flowchart for a method for effectively managing and/or
recuperating heat or thermal energy in an internal combustion
engine is shown in FIG. 5. Exhaust gas is collected in a volume in
step 502. Exhaust gas flows out of the volume in two portions in
step 504. A first portion of exhaust gas from the volume flows out
of the volume to form a tailpipe gas stream in step 506. A second
portion of exhaust gas from the volume flows out of the volume to
form an EGR gas stream in step 508. The tailpipe gas stream passes
through at least one turbine in step 510. If additional turbines
are present, the tailpipe gas stream may also pass through the
additional turbines. An amount of heat is transferred from the EGR
gas stream to the after-treatment stream in a heat exchanger. The
tailpipe gas stream passes through the heat exchanger in step 512
where it is heated by receiving heat from the EGR gas stream.
[0030] The EGR gas stream passes through the heat exchanger in step
514 where it is cooled by giving up heat to the tailpipe gas stream
and/or by convection to the environment. The EGR gas stream exits
the heat exchanger and passes through other engine components, for
example an EGR valve and/or an EGR cooler, before entering an
intake manifold of an engine in step 518. The tailpipe gas stream
exits the heat exchanger and passes through other engine and/or
vehicle components, for example a DPF and/or an oxidation catalyst,
before being released to the environment in step 520.
[0031] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative and not restrictive. The scope of
the invention is, therefore, indicated by the appended claims
rather than by the foregoing description. All changes that come
within the meaning and range of equivalency of the claims are to be
embraced within their scope.
* * * * *