Note: Descriptions are shown in the official language in which they were submitted.
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Description
ENGINE INLET AIR COOLING SYSTEM AND METHOD
Technical Field
The present disclosure relates generally to engine inlet air cooling
systems. Specifically, an embodiment of the present invention relates to an
inlet
air cooling system with a first compressor, a second compressor, and a cooling
circuit.
Background
Compressing engine inlet air in two or more compression stages
may benefit the efficiency of the combustion process of an internal combustion
engine by driving more air into the combustion cylinder. Denser inlet air may
also assist in meeting some governmental engine emission regulations.
Compared to inlet air passing through just one compression stage, inlet air
passing through two or more compression stages, may have a significantly
higher temperature. Compressing higher temperature air requires additional
work. Driving a turbine in the exhaust stream to drive a compression device in
a
second or subsequent compression stage, causes additional parasitic exhaust
gas
pumping, resulting in decreased engine efficiency. Cooling the inlet air
between
compression stages may allow the second or subsequent compressor devices to
operate more efficiently. After the compression stage, inlet air is often
passed
through one or more air cooling devices, to assist in controlling the
temperature
of air entering an engine combustion chamber, which may allow increased fuel
efficiency while meeting emission regulations. A more robust, and sometimes
more expensive, air cooler may be needed when using two or more compression
stages. In addition, more energy may be expended cooling the inlet air.
Some engine fuels, such as for example, liquid natural gas (LNG),
hydrogen (H2), ammonia (NH3), and mixtures of H2 and oxygen (02) are stored
in cryogenic storage tanks or other cold storage, and must be heated prior to
being combusted in an engine. The use of LNG has increased in some
applications and geographic regions as the infrastructure to support use and
lower fuel costs make is a desirable fuel. LNG, and other fuels, may be passed
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through a heat exchanger to both cool the inlet air and heat the fuel.
However, if
the inlet air has a high enough level of humidity, high levels of cooling may
create ice crystals. If passed through some compressors, the ice crystals may
cause damage.
United State Patent No. 8,220,268 to Callas discloses an engine
having a first compressor configured to pressurize inlet air, and a second
compressor configured to further pressurize the inlet air. The engine may also
have a cooling circuit fluidly located to cool the inlet air after the inlet
air is
pressurized by the first compressor and before the inlet air is further
pressurized
by the second compressor. The cooling circuit may have a first heat exchanger
configured to transfer heat from the inlet air to a fuel of the engine, and a
second
heat exchanger configured to transfer heat from exhaust of the engine to the
fuel
of the engine.
Summary of the Invention
In one aspect, a method of cooling inlet air to an engine includes
pressurizing the inlet air during a first compression stage, and further
pressurizing the inlet air during a second compression stage. Heat is
transferred
from the inlet air to a primary coolant liquid between the first compression
stage
and the second compression stage, and heat is transferred selectively,
variably,
or selectively and variably from the primary coolant liquid to a fuel of the
engine.
In another aspect, an engine inlet air cooling system includes a
first compressor configured to pressurize inlet air, a second compressor
configured to further pressurize the inlet air, and a cooling circuit. The
cooling
circuit includes a coolant heat exchanger, an inlet air heat exchanger, and a
fuel
cooled heat exchanger. The coolant heat exchanger is configured to transfer
heat
from a primary coolant liquid. The inlet air heat exchanger is configured to
transfer heat from the inlet air to the primary coolant liquid after the inlet
air
exits the first compressor and before the inlet air enters the second
compressor.
The fuel cooled heat exchanger is configured to selectively transfer heat from
the
primary coolant liquid to a fuel of the engine.
In another aspect, an engine inlet air cooling system includes an
inlet air heat exchanger, a coolant heat exchanger, a fuel cooled heat
exchanger,
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an inlet air circuit, a fuel circuit, and a primary coolant circuit. The inlet
air heat
exchanger includes an inlet air passage and a first primary coolant passage in
thermal communication. The coolant heat exchanger includes a second primary
coolant passage. The fuel cooled heat exchanger includes a fuel passage and a
third primary coolant passage in thermal communication. The inlet air circuit
includes a first compressor configured to pressurize inlet air, the inlet air
passage, and a second compressor configured to further pressurize the inlet
air,
wherein the inlet air passage fluidly connects the first compressor and the
second
compressor. The fuel circuit includes the fuel passage. The primary coolant
circuit includes the first primary coolant passage, the second primary coolant
passage, the third primary coolant passage, a fuel cooled heat exchanger
bypass,
and a control valve assembly. The second primary coolant passage fluidly
connects to the first primary coolant passage. The third primary coolant
passage
fluidly connects to the first primary coolant passage. The fuel cooled heat
exchanger bypass fluidly connects to the first primary coolant passage. The
control valve assembly selectively fluidly connects the second primary coolant
passage to the bypass, and selectively fluidly connects the second primary
coolant passage to the third primary coolant passage.
In another aspect, an engine system includes an engine, a fuel
source, a first compressor configured to pressurize inlet air, a second
compressor
configured to further pressurize the inlet air, and a cooling circuit. The
engine
includes an intake manifold, and a fueling device the second compressor
fluidly
connects to the intake manifold. The cooling circuit includes a coolant heat
exchanger, an inlet air heat exchanger, and a fuel cooled heat exchanger. The
coolant heat exchanger is configured to transfer heat from a primary coolant
liquid. The inlet air heat exchanger is configured to transfer heat from the
inlet
air to the primary coolant liquid after the inlet air exits the first
compressor and
before the inlet air enters the second compressor. The fuel cooled heat
exchanger
is configured to selectively transfer heat from the coolant liquid to a fuel
of the
engine, and fluidly connects the fueling device and the fuel source.
Brief Description of the Drawings
Fig. 1 schematically depicts an exemplary embodiment of an
engine inlet air cooling system.
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Fig. 2 schematically depicts another exemplary embodiment of an
engine inlet air cooling system.
Fig. 3 depicts a flow chart of an exemplary method of cooling
inlet air to an engine.
Detailed Description
Reference will now be made in detail to specific embodiments or
features, examples of which are illustrated in the accompanying drawings.
Generally, corresponding or similar reference numbers will be used, when
possible, to refer to the same or corresponding parts.
Referring now to Fig. 1, an exemplary embodiment of an air inlet
system 100 is illustrated. The air inlet system 100 includes a first
compressor
102 configured to pressurize inlet air, and a second compressor 104 configured
to further pressurize the inlet air. The air inlet system 100 provides
compressed
air to an engine 140. In one embodiment, the engine 140 may include an
internal
combustion engine with an intake manifold 142. In the internal combustion
engine embodiment, the first and second compressors 102, 104 may be
compressors of a twin compressor turbocharger or supercharger. Alternatively,
the first and second compressors 102, 104 may be compressors in a series
arrangement of turbochargers or superchargers. In other embodiments the engine
140 may include a turbine engine and the compressors 102, 104 may include
compressor sections of the turbine engine.
The inlet air system 100 further includes a cooling circuit 106
including an first inlet air heat exchanger 108 configured to transfer heat
from
the inlet air to a primary coolant liquid after the inlet air exits the first
compressor 102 and before the inlet air enters the second compressor 104. The
first inlet air heat exchanger 108 may include a first inlet air passage 110
in
thermal communication with a first primary coolant passage 112. As the inlet
air
flows through the first inlet air passage 110, thermal energy 114 may be
transferred to primary coolant liquid flowing through the primary coolant
passage 112. The first inlet air heat exchanger 108 may include a double pipe
heat exchanger, a shell and tube heat exchanger, or any other heat exchanger
known in the art. The primary coolant may include water, glycol, another
refrigerant, or any other coolant as known in the art.
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The cooling circuit 106 includes a coolant heat exchanger 116
configured to transfer heat from the primary coolant liquid. In the
illustrated
embodiment, the coolant heat exchanger 116 includes a radiator type heat
exchanger including a second primary coolant passage 118, a fan shroud 120,
and a fan 122. The fan 122 may direct a secondary coolant 124, illustrated as
air,
through the coolant heat exchanger 116. Heat from the primary coolant liquid
in
the second primary coolant passage 118 may be transferred to the air as it is
directed through the coolant heat exchanger 116. In other embodiments the
coolant heat exchanger 116 may include other heat exchangers known in the art.
The cooling circuit 106 includes a fuel cooled heat exchanger 126
configured to selectively transfer heat from the primary coolant liquid to a
fuel
of the engine 140. The fuel cooled heat exchanger 126 may include a first fuel
passage 128 in thermal communication with a third primary coolant passage 130.
As primary coolant liquid selectively flows through the third primary coolant
passage 130, thermal energy 132 may be transferred to fuel flowing through the
first fuel passage 128. The fuel heat exchanger 126 may include a double pipe
heat exchanger, a shell and tube heat exchanger, or any other heat exchanger
known in the art. The fuel may include a cryogenically stored fuel such as
LNG,
H2, NH3, or mixtures of H2 and 02, or any other engine fuel as known in the
art.
The inlet air system 100 includes an inlet air circuit 134 fluidly
connecting inlet air from the environment (not shown) surrounding the engine
140, or another inlet air source (not shown) to the engine 140. The inlet air
circuit 134 includes the first compressor 102 and the second compressor 104.
The inlet air circuit 134 may include the first inlet air passage 110 fluidly
connecting the first compressor 102 and the second compressor 104. In the
embodiment illustrated, elements of the inlet air circuit 134 are fluidly
connected
by air conduits 136 illustrated by solid lines with no cross hatches.
The inlet air circuit 134 may include a second inlet air heat
exchanger 138 fluidly connecting the second compressor 104 to the engine 140.
The second inlet air heat exchanger 138 may be configured to transfer heat
from
the inlet air to another medium after the inlet air exits the second
compressor 102
and before the inlet air enters the engine 140. The second inlet air heat
exchanger
138 may include a second inlet air passage 135 in thermal communication with a
second fuel passage 143. A valve 137 may selectively direct fuel through the
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second fuel passage 143. As the inlet air flows through the second inlet air
passage 135, thermal energy 139 may be transferred to fuel flowing through the
second fuel passage 143. The second inlet air heat exchanger 138 may include a
double pipe heat exchanger, a shell and tube heat exchanger, or any other heat
exchanger known in the art. Although illustrated as a fuel cooled heat
exchanger,
in other embodiments the other mediums may be used as coolants as are known
in the art. Some embodiments of the inlet air circuit 134 may not include the
second inlet air heat exchanger 138.
Inlet air may flow into the inlet air circuit 134, flow through and
be pressurized by the first compressor 102, flow through the first inlet air
passage 110 and transfer heat to the primary coolant liquid, flow through and
be
further pressurized by the second compressor 104, flow through the second
inlet
air passage 135 and transfer heat to the fuel, and flow into the intake
manifold
142 of the engine 140, as illustrated by the outlined arrows.
In the illustrated embodiment, the system 100 includes a fuel
circuit 144 fluidly connecting a fuel source 146 with a fueling device 148.
The
fuel circuit 144 may provide fuel for the engine 140, direct fuel through the
first
fuel passage 128, and selectively direct fuel through the second fuel passage
143.
The fueling device 148 may include a fuel injector 150. Fuel conduits 152,
illustrated by solid lines with double cross hatches, may fluidly connect
elements
of the fuel circuit 144. Fuel may flow from the fuel source 146, flow through
the
first fuel passage 128 and absorb thermal energy from the primary coolant,
selectively flow through the second fuel passage 143 and absorb thermal energy
from the inlet air, flow to the fuel injector 150, and be injected into the
engine
140 during the combustion process. Valve 137 may be actuated to control the
flow of fuel through the second fuel passage 143. A check valve 141 may aid in
ensuring the desired direction of fuel flow through the second fuel passage
143.
Fuel flow is illustrated by the patterned arrows.
In the illustrated embodiment, the inlet air system 100 includes a
primary coolant circuit 154 including the first primary coolant passage 112,
the
second primary coolant passage 118, a primary coolant bypass 156, a primary
coolant circuit branch 157, and a control valve assembly 158 for selectively,
variably, or selectively and variably directing primary coolant liquid through
the
bypass 156 and/or the branch 157. The control valve assembly 158 may include
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a variable orifice valve 160 for directing and varying the flow of primary
coolant
liquid into the bypass 156, and a variable orifice valve 162 for directing and
varying the flow of primary coolant liquid into the branch 157. The primary
coolant circuit 154 may also include a pump 164 for pressurizing primary
coolant liquid to flow through the primary coolant circuit 154. The pump 164
is
illustrated as a fixed displacement, unidirectional pump and may be driven by
a
mechanical link to engine 140. In other embodiments, the pump 164 may include
a variable displacement pump, and may be driven by other power sources such
as an electric motor. Although illustrated as a single unit, pump 164 may also
include multiple pumps placed at one or multiple locations in the primary
coolant circuit 154.
The primary coolant circuit 154 may include a mixing valve
assembly 166 for mixing primary coolant liquid from the bypass 156 and the
branch 157. Primary coolant conduits 168, illustrated by the solid lines with
a
single cross hatch, may fluidly connect elements of the primary coolant
circuit
154.
Primary coolant liquid may flow from the first primary coolant
passage 110, flow through the second primary passage 118 and transfer thermal
energy to the secondary coolant liquid, flow through and be pressurized by the
pump 164, flow through the control valve assembly 158, and be selectively,
variably, or selectively and variably directed into the bypass 156 and/or the
branch 157. Some or all of the primary coolant liquid flow from the pump 164
may be directed through the variable orifice valve 160 into the bypass 156 and
flow to the mixing valve 166. Some or all of the primary coolant liquid flow
from the pump 164 may also, or alternatively, be directed through the variable
orifice valve 162 into the branch 157, flow through the third primary coolant
passage 130 and transfer thermal energy to the fuel, and flow to the mixing
valve
166. Primary coolant liquid from the bypass 156 and the branch 157 may flow
through and be mixed by the mixing valve 166, and then flow through the first
primary coolant passage 112 and absorb thermal energy from the inlet air. The
flow of primary coolant liquid is illustrated by the solid arrows.
To selectively, variably, or selectively and variably control the
transfer of heat from the primary coolant liquid to the fuel, the system 100
may
include an electronic or computerized control unit, module, or controller 202.
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The controller 202 may receive signals generated by sensors and/or calculated
as
functions of various system and/or engine parameters, and coordinate and
control the flow of the primary coolant through the bypass 156, and/or the
branch 157 as a function of the signals and/or parameters. The controller 202
may also coordinate and control other components or functions associated with
the engine 140 and/or the inlet air system 100, such as, for example, fuel
injections by the fuel injector 150.
The controller 202 can include a microprocessor, an application
specific integrated circuit (ASIC), or other appropriate circuitry and can
have
memory or other data storage capabilities. The controller 202 can include
functions, steps, routines, data tables, data maps, charts, and the like,
saved in,
and executable from, read only memory, or another electronically accessible
storage medium, to control the engine 140 and air inlet system 100. Although
the controller 202 is illustrated as a single, discrete unit, in other
embodiments,
the controller 202 and its functions may be distributed among a plurality of
distinct and separate components. The single unit or multiple component
controller 202 may be located on-board the engine 140 or a machine associated
with the air inlet system 100, and/or in a remote location. To receive
operating
parameters and send control commands or instructions, the controller 202 can
be
operatively associated with and can communicate with various sensors and
controls on the engine 140 and air inlet system 100. Communication between
the controller 202 and the sensors can be established by sending and receiving
digital or analog signals across electronic communication lines or
communication busses. In some embodiments the communication between the
controller 202 and the sensors may be by radio, satellite, and/or
telecommunication channels. These communication connections are illustrated
with dashed lines.
To measure the flow rate, pressure and/or temperature of the inlet
air at various locations in the inlet air circuit 134, the controller 202 can
be
communicatively connected with one or more inlet air sensors 203. The inlet
air
sensors 203 may also determine or sense the barometric pressure, humidity, or
other environmental conditions in which the engine 140 and inlet air system
100
is operating. In the illustrated embodiment, exemplary air sensors 203 include
a
humidity sensor 204, a first inlet air temperature sensor 206, and a second
inlet
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air temperature sensor 208. The humidity sensor 204 is disposed at or near the
location that the inlet air enters the inlet air circuit 134, and is
configured to
generate a signal indicative of the humidity of the inlet air. The first
temperature
sensor 204 is disposed between the first compressor 102 and the first inlet
air
passage 110 and is configured to generate a signal indicative of the
temperature
of the inlet air flowing out of the first compressor 102. The second
temperature
sensor 206 is disposed between the second compressor 104 and the second inlet
air heat exchanger 138, and is configured to generate a signal indicative of
the
temperature of the inlet air flowing out of the second compressor 104. In
other
embodiments other inlet air sensors 203 may be disposed at other locations in
the inlet air circuit 134 to sense characteristics of the inlet air at those
locations.
To monitor the temperature of the primary coolant liquid at
various locations in the coolant circuit 154, the controller 202 can be
communicatively connected with one or more coolant temperature sensors 210.
Although only one coolant temperature sensor 210, located between the mixing
valve 166 and the first primary coolant passage 112, is illustrated,
additional
coolant temperature sensors 210 may be located at other locations in the
coolant
circuit 154. The controller 154 may receive temperature signals from the one
or
more coolant temperature sensors 210 and may calculate temperatures at other
locations in the coolant circuit 154.
The controller 202 can be communicatively connected to and
control the actuation of the control valve assembly 158 to control the flow of
primary coolant liquid through the third primary coolant passage 130. As
illustrated, the controller 202 is communicatively connected to a variable
orifice
valve 160 to control the flow of primary coolant through the bypass 156, and
to a
variable orifice valve 162 to control the flow of primary coolant liquid
through
the branch 157. Those skilled in the art will realize that other
configurations of
the control valve assembly 158 are possible to control the flow of primary
coolant liquid through the third primary coolant passage 130, and these
configurations are contemplated embodiments. Controller 202 can be
communicatively connected to and control the actuation of valve 137 to
selectively, variably, or selectively and variable control the flow of fuel
through
second fuel passage 143.
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Referring now to Fig. 2, another exemplary embodiment of air
inlet system 100 is illustrated. In this embodiment a third compression stage
is
added; inlet air flows through a third inlet air heat exchanger 180 between
the
second and third compression stages; and the fuel cooled second inlet heat
exchanger 138, fuel passage 143 and associated valves 137, 141 are not
included. An alternative embodiment of the fuel heat exchanger 126 may
transfer thermal energy from primary coolant to the fuel through a conductive
liquid. The valve assembly 158 selectively, variably, or selectively and
variably
directs primary coolant through a fourth primary coolant passage 174 (in
addition to the third primary coolant passage 130) included in the fuel heat
exchanger 126. Primary coolant flows to both the first inlet air heat
exchanger
108 and the third inlet air heat exchanger 180, in parallel, after exiting the
fuel
heat exchanger 126 and/or bypass 156 and a second bypass 188. Elements of the
embodiment of system 100 in Fig. 2 not described below are similar to those
shown and described in relation to Fig. 1.
The inlet air circuit 134 in the illustrated embodiment includes a
third compressor 170, and a third inlet air heat exchanger 180. The third
compressor 170 is configured to further pressurize inlet air flowing from the
second compressor 104 and provide the compressed air to the engine. Similar to
the other compressors 102, 104, the third compressor 170 may be a compressor
in a turbocharger Of other supercharger, Of a compressor section of a turbine
engine.
The third inlet air heat exchanger 180 is configured to transfer
heat from the inlet air to the primary coolant liquid after the inlet air
exits the
second compressor 104 and before the inlet air enters the third compressor
170.
The third inlet air heat exchanger 170 may include a third inlet air passage
182 in
thermal communication with a fifth primary coolant passage 184. As the inlet
air
flows through the third inlet air passage 182, thermal energy 186 may be
transferred from the inlet air to primary coolant liquid flowing through the
fifth
primary coolant passage 184. The third inlet air heat exchanger 180 may
include
a double pipe heat exchanger, a shell and tube heat exchanger, or any other
heat
exchanger known in the art.
Inlet air may flow into the inlet air circuit 134, flow through and
be pressurized by the first compressor 102, flow through the first inlet air
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passage 110 and transfer heat to the primary coolant liquid, flow through and
be
further pressurized by the second compressor 104, flow through the third inlet
air
passage 182 and transfer heat to the primary coolant liquid, flow through and
be
further pressurized by the third compressor 170, and flow into the intake
manifold 142 of the engine 140, as illustrated by the outlined arrows.
Although
not illustrated in Fig. 2, a second inlet air heat exchanger 138, as shown and
described in relation to Fig. 1, may cool the inlet air between the third
compressor 170 and the engine 140.
In the alternative embodiment of the fuel cooled heat exchanger
126, the first fuel passage 128 may include several coolant passages; and the
third primary coolant passage 130 may include multiple cooling passages 172,
through which the primary coolant variably, selectively, or variably and
selectively flows. The fuel cooled heat exchanger 126 may additionally include
the fourth primary coolant passage 174 including multiple coolant passages 172
through which the primary coolant variably, selectively, or variably and
selectively flows. The first fuel passage 128, third primary coolant passage
130,
and fourth primary coolant passage 174 may be surrounded by a thermally
conductive liquid 178 contained in a tank through which the passages 128, 130,
174 are routed through. As primary coolant liquid selectively flows through
the
third primary coolant passage 130, and/or the fourth primary coolant passage
174, thermal energy may be transferred to the conductive liquid 178, and from
the conductive liquid 178 to the fuel flowing through the first fuel passage
128.
In the illustrated embodiment, the primary coolant circuit 154
additionally includes the fifth primary coolant passage 184 of the third inlet
air
heat exchanger 180; and the fourth primary coolant passage 174 and a second
coolant bypass 188 for selectively, variably, or selectively and variably
directing
primary coolant to the fifth primary coolant passage 184. The control valve
assembly 158 alternatively includes two selective and variable valves 176. The
pump 164 may be selectively, variably, or selectively and variably connected
with the third primary coolant passage 130 and/or the bypass 156 through one
of
the valves 176. The valve 176 may direct fluid from the pump to any of, or all
of
the multiple passages 172 and/or the bypass 156. After primary coolant passes
through the third primary coolant passage 130 and/or the bypass 156, the
primary coolant flows into the mixing valve 166 and then to the first primary
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coolant passage 112. The pump 164 may also be selectively, variably, or
selectively and variably connected with the fourth primary coolant passage 174
and/or the second bypass 188 through the other valve 176. The valve 176 may
direct fluid from the pump to any of, or all of the multiple passages 172
and/or
the bypass 188. After primary coolant passes through the fourth primary
coolant
passage 174 and/or the bypass 188, the primary coolant flows into the mixing
valve 166 and then to the fifth primary coolant passage 184.
Primary coolant liquid may flow from the first primary coolant
passage 112, flow through the second primary coolant passage 118 and transfer
thermal energy to the secondary coolant liquid, flow through and be
pressurized
by the pump 164, flow through the control valve assembly 158, and be
selectively, variably, or selectively and variably directed into the third
primary
coolant passage 130, the fourth primary coolant passage 174, the bypass 156,
and/or the second bypass 188. Primary coolant liquid flowing through the third
primary coolant passage 130 and the fourth primary coolant passage 174 may
transfer thermal energy to the conductive liquid 178 which may transfer
thermal
energy to the fuel. Primary coolant liquid from the third coolant passage 130
and
the bypass 156 may flow through and be mixed by the mixing valve 166, and
then flow through the first primary coolant passage 112 and absorb thermal
energy from the inlet air. Primary coolant liquid from the fourth coolant
passage
174 and the second bypass 188 may flow through and be mixed by the mixing
valve 166, flow through the fifth primary coolant passage 184 and absorb
thermal energy from the inlet air, and then flow back through the second
primary
coolant passage 118.
The controller 202 may receive signals generated by sensors
and/or calculated as functions of various system and/or engine parameters, and
coordinate and control the flow of the primary coolant through the third
primary
coolant passage 130, the fourth primary coolant passage 174, the bypass 156,
and/or the second bypass 188 as a function of the signals and/or parameters.
In the embodiment of Fig. 2, the inlet air sensors 203 additionally
include a third inlet air temperature sensor 212, and a fourth inlet air
temperature
sensor 214. The third temperature sensor 212 is disposed between the third
inlet
air passage 182 and the third compressor 170, and is configured to generate a
signal indicative of the temperature of the inlet air flowing out of the third
inlet
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air heat exchanger 180. The fourth temperature sensor 214 is disposed between
the third compressor 170 and the intake manifold 142, and is configured to
generate a signal indicative of the temperature of the inlet air flowing out
of the
third compressor 170.
The coolant temperature sensors 210 of the embodiment
illustrated in Fig. 2 include one coolant temperature sensor 210 located
between
the mixing valve 166 and the first primary coolant passage 112, and another
coolant temperature sensor 210 located between the mixing valve 166 and the
fifth primary coolant passage 184. The coolant temperature sensors 210 are
communicatively connected to the controller 202.
In the illustrated embodiment, the controller 202 is
communicatively connected to and controls the actuation of the control valve
assembly 158 to selectively, variably, or selectively and variably control the
flow
of primary coolant liquid through the third primary coolant passage 130, the
fourth primary coolant passage 174, the bypass 156, and the second bypass 188.
Industrial Applicability
Cooling the inlet air to an engine 140 between compression stages
may assist in raising the efficiency of the second compressor 104 and/or third
compressor 170 and in reducing the level of cooling needed after the final
compression stage, before the inlet air enters the intake manifold 142.
Transferring heat to a fuel stored cryogenically, may not only cool the inlet
air,
but may provide necessary heat to the fuel as well, making the system 100 more
efficient. In some circumstances, such as high humidity, it may be necessary
to
control cooling before or between compression stages to prevent ice crystals
formation which might damage a compressor 104, 170 or other undesirable
conditions.
Referring now to Fig. 3, a flow chart of an exemplary method 300
of cooling inlet air to an engine is illustrated. The method 300 includes
pressurizing the inlet air during a first compression stage, further
pressurizing
the inlet air during a second compression stage, transferring heat from the
inlet
air to a primary coolant liquid between the first compression stage and the
second compression stage, and selectively, variably, or selectively and
variably
transferring heat from the primary coolant liquid to a fuel of the engine.
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The method 300 starts at step 302 and proceeds to step 304. In
step 304 inlet air is pressurized during a first compression stage. In the
embodiment of the air inlet cooling system 100 illustrated in Fig. 1, inlet
air
enters the inlet air circuit 134 and is pressurized in the first compressor
102. As
the inlet air is compressed, the inlet air temperature rises. The method 300
proceeds to step 306. In step 306 heat is transferred from the inlet air to a
primary coolant liquid between the first compression stage and the second
compression stage. In the embodiment of the air inlet cooling system 100
illustrated in Fig. 1, the inlet air flows through the first inlet air passage
110 of
the first inlet air heat exchanger 108 between the first compression stage and
the
second compression stage. The first inlet air passage 110 is in thermal
communication with the first primary coolant passage 112 of the first inlet
air
heat exchanger 108, and heat is transferred from the inlet air flowing through
the
first inlet air passage 110 to the primary coolant liquid flowing through the
first
primary coolant passage 112. The method 300 proceeds to step 308.
In step 308, the inlet air is further pressurized during a second
compression stage. In the embodiment of the air inlet cooling system 100
illustrated in Fig. 1, the inlet air flows from the first compressor 102,
through the
first inlet air passage 110 and enters the second compressor 104, where the
inlet
air is further pressurized.. The method 300 proceeds to step 310.
In step 310, heat is transferred from the primary coolant liquid to
a secondary coolant liquid. After absorbing thermal energy while flowing
through the first primary coolant passage 112, the primary coolant liquid in
the
embodiment of system 100 of Fig. 1, flows into and through the second primary
coolant passage 118 of the coolant heat exchanger 116. The secondary coolant
liquid 124 is directed through the coolant heat exchanger 116 by the fan 122
and
fan shroud 120. Heat is transferred from the primary coolant liquid flowing
through the second primary cooling passage 118 to the secondary coolant liquid
124. The method 300 proceeds to step 312.
In step 312, heat is selectively transferred from the primary
coolant liquid to a fuel of the engine 140 with a fuel heat exchanger 126. In
the
embodiment of system 100 illustrated in Fig. 1, some or all of the primary
coolant liquid may be directed into the circuit branch 157, and thus into the
third
primary coolant passage 130. The primary coolant liquid flows from the second
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primary coolant passage 118, and then flows through and is pressurized by the
pump 164, and flows into the control valve assembly 158. The control valve
assembly 158 may selectively direct some or all of the primary coolant liquid
into the third primary coolant passage 130 of the fuel cooled heat exchanger
126.
Thermal energy is transferred from primary coolant liquid flowing through the
third primary coolant passage 130 to fuel flowing through the first fuel
passage
128 of the fuel cooled heat exchanger 126.
In the embodiment of system 100 illustrated in Fig. 2, the control
valve assembly 158 may direct primary coolant liquid through one, some, all,
or
none of the multiple coolant passages 172 of the third primary coolant passage
130 and the fourth primary coolant passage 174, and/or the bypass 156 and
second bypass 188. The controller 202 may control the valves 176 to select
which of the multiple coolant passages 172 and bypasses 156, 188 to direct
primary coolant through as a function of desired thermal energy transfer 114,
186 in the inlet air heat exchangers 108, 180. Thermal energy is transferred
from
primary coolant liquid flowing through the third primary coolant passage 130
and the fourth primary coolant passage to fuel flowing through the first fuel
passage 128 of the fuel cooled heat exchanger 126.
It may be necessary to heat fuel stored cryogenically, or by other
cold storage methods, before the fuel may be used in the combustion process of
the engine 140. In the embodiments of system 100, illustrated in Figs. 1 and
2,
fuel may be stored cryogenically in fuel source 146. Fuel source 146 may, for
example, include a cryogenic fuel tank for storing LNG. LNG may flow from the
fuel source 146 through first fuel passage 128. Thermal energy may be
transferred to the LNG flowing through first fuel passage 128 from primary
coolant liquid flowing through the third primary coolant passage 130. The
heated
LNG may flow through other fuel conditioning and heating devices (not shown)
to fueling device 150, and be injected into a combustion chamber of the engine
140. By transferring thermal energy from the primary coolant liquid to the LNG
in the fuel cooled heat exchanger, energy which might have been needed to heat
the LNG, or cool the primary coolant liquid may be saved. The method proceeds
to step 314.
In steps 314, 316, 318, and 320, system 100 parameters are
determined. In system 100, as illustrated in Fig. 1, these parameters may be
used
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to control the flow of primary coolant liquid directed through the branch 157,
and thus the fuel cooled heat exchanger 126, and/or to control the flow of
primary coolant liquid directed through the bypass 156. In system 100, as
illustrated in Fig. 2, these parameters may be used to control the flow of
primary
coolant liquid directed through one, some, all or none of the multiple coolant
passages 172, and thus the fuel cooled heat exchanger 126, and/or the bypasses
156, 188. In both illustrated embodiments, in step 314, the inlet air
temperature
sensor 306 generates a signal indicative of the temperature of the inlet air
when
it exits the first compressor 102. In both illustrated embodiments, in step
316, the
inlet air temperature sensor 208 generates a signal indicative of the
temperature
of the inlet air when it exits the second compressor 104. In both illustrated
embodiments, in step 318, the humidity sensor 204 generates a signal
indicative
of the humidity of the inlet air as it enters the inlet air circuit 134. In
both
illustrated embodiments, in step 320, the coolant temperature sensor 210
generates a signal indicative of the temperature of the primary coolant liquid
as it
flows into the first primary coolant passage 112. In the embodiment
illustrated in
Fig. 2, a second coolant temperature sensor 210 generates a signal indicative
of
the temperature of the primary coolant liquid as it flows into the fifth
primary
coolant passage 184. The controller 202 may receive the sensor 204, 206, 208,
210 signals and generate command signals to the control valve assembly 158 as
a function of the sensor 204, 206, 208, 210 signals and other system 100 or
engine 140 parameters. In the embodiment illustrated in Fig. 2, other
parameters
may include a signal generated by inlet air temperature sensor 212 indicative
of
the temperature of the inlet air as it enters the third compressor 170; and a
signal
generated by inlet air temperature sensor 214 indicative of the temperature of
the
inlet air as it exits the third compressor 170. The method 300 proceeds to
step
322.
In step 322, as illustrated in Fig. 1, the controller 202 may control
the actuation of the control valve assembly 158 to direct some or all of the
primary coolant liquid through the bypass 156 as a function of the inlet air
temperature and humidity, and the primary coolant liquid temperature. In the
embodiment illustrated in Fig. 2, the controller 202 may control the actuation
of
the control valve assembly 158 to direct primary coolant liquid through one,
some, all, or none of the multiple coolant passages 172 and/or the bypasses
156,
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188 as a function of the inlet air temperature and humidity, and the primary
coolant liquid temperature. The controller 202 may include logic in a memory
which may be executed on a processor to ensure that the temperature of the
inlet
air exiting the second compressor 104 (and/or third compressor 170 in relation
to
Fig. 2) does not exceed a maximum air temperature value. That maximum air
temperature value may be set to ensure that the second inlet air heat
exchanger
138 and/or other air inlet circuit elements are not damaged. The controller
202
may also include logic to ensure that inlet air exiting the first inlet air
heat
exchanger 108 (and third inlet air exchanger 180 in relation to Fig. 2) does
not
include ice crystals which may damage the second compressor 104 (and/or third
compressor 170 in relation to Fig. 2). The logic may be in the form of tables,
equations, or other functions as is known in the art. Examples of logic may
include directing all or most of the flow of primary coolant liquid through
the
branch 157 (or the third coolant passage 130 and fourth coolant passage 174 in
relation to Fig. 2), and thus the fuel cooled heat exchanger 126, when the
inlet
air humidity is below a set humidity value such that ice crystals may not
form.
The logic may include dividing the flow of the primary coolant liquid when
inlet
air humidity is above the set humidity value, between the branch 157 (or the
third coolant passage 130 and fourth coolant passage 174 in relation to Fig.
2)
and the bypass 156 (and/or second bypass 188 in relation to Fig. 2), such that
the
temperature of the flow of inlet air into the second compressor 104 (and/or
third
compressor 170 in relation to Fig. 2) is high enough that ice crystals may not
form, and the temperature of the flow of inlet air exiting of the second
compressor 104 (and/or third compressor 170 in relation to Fig. 2) is low
enough
that inlet air circuit 134 elements are not damaged. The temperature of inlet
air
entering the second compressor 104 may be calculated as a function of the
inlet
air temperature exiting the first compressor 102, the primary coolant
temperature
entering the first inlet air heat exchanger 108, and the geometry of the
system
100, as would be known in the art. Similar calculations may be used to
determine the temperature of inlet air entering the third compressor 170 in
Fig. 2.
In another embodiment, a sensor (not shown) could measure the temperature
directly. The amount of primary coolant liquid flow required in the bypass 156
(and/or second bypass 188 in relation to Fig. 2) and/or in the branch 157 (or
multiple coolant passages 172 in relation to Fig. 2) to achieve the desired
inlet
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air temperature may be calculated as a function of system 100 or engine
parameters and the geometry of the system through algorithms, look-up tables,
maps, or other methods as are known in the art. The controller 202 may actuate
the control valve assembly 158 to achieve the desired flows as is known in the
art. The method 300 proceeds to step 324.
In step 324, primary coolant liquid from the bypass circuit 156
(and secondary bypass circuit 188 for Fig. 2) and primary coolant exiting the
fuel heat exchanger 126 are mixed. In the embodiment illustrated in Fig. 1,
primary coolant liquid from the branch 157 and the bypass 156 are directed
into
a mixing valve 166, and then directed into the first primary coolant passage
112.
In the embodiment illustrated in Fig. 2, primary coolant from the third
primary
coolant passage 130 and the bypass circuit 156 are directed into a mixing
valve
166, and then directed into the first primary coolant passage 112. In
addition,
primary coolant from the fourth primary coolant passage 174 and the second
bypass circuit 188 are directed into a mixing valve 166, and then directed
into
the fifth primary coolant passage 184.The method proceeds to step 326 and
ends.
It will be appreciated that the foregoing description provides
examples of the disclosed system and technique. However, it is contemplated
that other implementations of the disclosure may differ in detail from the
foregoing examples. All references to the disclosure or examples thereof are
intended to reference the particular example being discussed at that point and
are
not intended to imply any limitation as to the scope of the disclosure more
generally. All language of distinction and disparagement with respect to
certain
features is intended to indicate a lack of preference for those features, but
not to
exclude such from the scope of the disclosure entirely unless otherwise
indicated.
