GB2544051A

GB2544051A - An energy recovery system for an internal combustion engine

Info

Publication number: GB2544051A
Application number: GB1519385.7A
Authority: GB
Inventors: Saville Allan; Dris Antonis; Bernard Guillaume
Original assignee: Perkins Engines Co Ltd
Current assignee: Perkins Engines Co Ltd
Priority date: 2015-11-03
Filing date: 2015-11-03
Publication date: 2017-05-10
Anticipated expiration: 2035-11-03
Also published as: GB2544051B; GB201519385D0

Abstract

An energy recovery system 112, for an internal combustion engine 100, comprising a first heat exchanger 114, a first turbine 118, a first compressor 120 and a second heat exchanger 116, where the first heat exchanger transfers heat from an exhaust gas stream 110 of the engine to a working fluid in a fluid circuit 113 and where the first turbine is located in the fluid circuit and is configured to be driven by the heated working fluid from the first heat exchanger and drives at least one of the first compressor, an exhaust gas compressor and a cooling system. The first compressor is configured to compress intake air to the engine. The exhaust gas compressor is configured to compress exhaust gas from the engine. The second heat exchanger is located in the fluid circuit positioned downstream of the first turbine and upstream of the pump, the second heat exchanger being configured to extract heat from the working fluid. The system may run on an organic Rankine cycle.

Description

AN ENERGY RECOVERY SYSTEM FOR AN INTERNAL COMBUSTION

ENGINE

Technical Field [0001] The present disclosure relates to an energy recovery system for an internal combustion engine.

Background [0002] Combustion engines such as diesel engines, gasoline engines, and gaseous fuel-powered engines are supplied with a mixture of air and fuel for combustion within the engine that generates a mechanical power output. These engines can generate mechanical power at low cost with efficiencies of 25% to 45% using commonly available fuels such as gasoline, natural gas or diesel fuel. In order to maximize the power output generated by this combustion process, the engine is often equipped with an exhaust manifold in fluid communication with a turbocharger or other such air induction system.

[0003] A conventional turbocharger utilizes an exhaust stream to drive a turbine. The turbine drives a compressor, which is configured to introduce more air into the combustion chamber. This increased amount of air allows for enhanced combustion in the combustion chamber, thereby increasing the power output generated by the engine at the cost of a slight increase in pumping losses. However, the high temperature of the exhaust stream is wasted.

[0004] US Patent No. 8,302,399 discloses a mobile organic Rankine cycle using the heat from an exhaust unit of a combustion engine to drive a turbine to produce useful work.

Summary of the Invention [0005] In one aspect of the present disclosure, an energy recovery system for an internal combustion engine is disclosed. The energy recovery system includes a first heat exchanger, a first turbine, a first compressor and a second heat exchanger. The first heat exchanger is configured to transfer heat from an exhaust gas stream of the engine to a working fluid in a fluid circuit. The first turbine is located in the fluid circuit and is configured to be driven by the heated working fluid from the first heat exchanger. Further, the first turbine is configured to drive at least one of the first compressor, an exhaust gas compressor and a cooling system. The first compressor is configured to compress intake air to the engine. The exhaust gas compressor is configured to compress exhaust gas from the engine. The second heat exchanger located in the fluid circuit positioned downstream of the first turbine and upstream of the pump, the second heat exchanger being configured to extract heat from the working fluid.

[0006] In another aspect of the present disclosure, an engine system is disclosed. The engine system comprises an internal combustion engine and the aforementioned energy recovery system. The engine system further comprises at least one of: a first compressor arranged to compress intake air to the engine; an exhaust gas compressor arranged to compress exhaust gas from the engine; and a cooling system.

[0007] In yet another aspect of the present disclosure, a method of operating an engine system is disclosed. The method including transferring heat from an exhaust stream of the engine to a working fluid in a fluid circuit using a first heat exchanger; driving a first turbine by the working fluid from the first heat exchanger, to drive at least one of a first compressor, an exhaust gas compressor and a cooling system. The first compressor is configured to compress the intake air to the engine, the exhaust gas compressor configured to compress exhaust gas from the engine. The method further includes extracting energy from the working fluid discharged by the first turbine in a second heat exchanger positioned between the first turbine and the first heat exchanger in the fluid circuit.

Brief Description of the Drawings [0008] FIG. lisa diagrammatic illustration of an exemplary engine operating to produce output work.

[0009] FIG. 2 is a schematic illustration of an exemplary engine system comprising the disclosed energy recovery system and an internal combustion engine.

[0010] FIG. 3 is a schematic illustration of an alternate configuration of an engine system comprising an exemplary energy recovery system and internal combustion engine.

[0011] FIG. 4 is a schematic illustration of yet another alternate configuration of an engine system comprising an exemplary energy recovery system and internal combustion engine.

[0012] FIG. 5 is a schematic illustration of yet another alternate configuration of an engine system comprising an exemplary energy recovery system and internal combustion engine.

[0013] FIG. 6 is a schematic illustration of yet another alternate configuration of an engine system comprising an exemplary energy recovery system and internal combustion engine.

[0014] FIG. 7 depicts a method of turbocharging an engine using an energy recovery system of the present disclosure.

Detailed Description [0015] The present disclosure relates to an energy recovery system for an engine system. FIG. 1 illustrates an exemplary engine system 90 comprising an internal combustion engine 100 having a combustion chamber 102. In an exemplary embodiment, the engine 100 may be any type of an internal combustion engine for a ground engaging machine or a power producing unit. In various other embodiments, the engine 100 may be any engine running on solid, liquid or gaseous fuel, used for various purposes such as an automobile, a construction machine, any transportation vehicle or the like.

[0016] The combustion chamber 102 includes a piston 104, an air intake port 106 and an exhaust port 108. The air intake port 106 may be configured to introduce fresh air/air-fuel mixture into the combustion chamber 102. The exhaust port 108 may be configured to facilitate removal of products of combustion, particularly exhaust gases 110, from the combustion chamber 102.

[0017] The exhaust port 108 is driven by a cam (not shown) mounted on a camshaft (not shown) driven at the same speed as crankshaft (not shown). Starting from when the piston 104 has reached its uppermost point of travel (top dead center), the combustion chamber 102 contains an explosive mixture of air and fuel under pressure. The exhaust port 108 is maintained in the closed position when the piston 104 at its uppermost point. On ignition of the mixture, the power stroke begins as piston 104 is forced downward and imparts a torque to the crankshaft (not shown). The cam (not shown) operates so as to open the exhaust port 108 toward the end of the downward stroke of the piston 104. This opening of the exhaust port 108 facilitates removal of hot combusted products, particularly exhaust gases 110, out of the combustion chamber 102.

[0018] The hot exhaust gases 110 exiting the combustion chamber 102 are provided to an energy recovery system 112 running on an organic Rankine cycle, which may be configured to provide compressed intake air to the engine 100, provide cooling or compress the exhaust gas from the engine 100 (as discussed in further detail below). The energy recovery system 112 may be mounted near the exhaust port 108 of the engine 100. The energy recovery system 112 may be a part of the engine system 90. The energy recovery system 112 is configured to utilize the heat of the exhaust gases 110 using a working fluid, which may be an organic working fluid, circulating in the system to force pressurized air into the combustion chamber 102. Any organic working fluid (i.e. one with a liquid-vapour phase change at a lower temperature than that of the water-steam phase change) suitable for use in an organic Rankine cycle may be used. The organic working fluid may comprise propane, butane, pentafluoro-propane, pentafluoro-butane, pentafluoro-polyether, silicone oil, ethyl alcohol, cyclo-hexane, cyclopropane, cyclo-pentane, cyclo-butane, thiophene, ketones, aromatics, and/or combinations thereof.

[0019] The energy recovery system 112 comprises a fluid circuit 113 having a first heat exchanger 114, a second heat exchanger 116, a first turbine 118, a pump 144 and a first compressor 120. The first heat exchanger 114 may be an evaporator and the second heat exchanger 116 may be a condenser. As one of skill in the art will appreciate, the first heat exchanger 114 and the second heat exchanger 116 may be any type of heat exchanger known in the art that is adapted to transfer energy from one fluid to the other.

[0020] The first heat exchanger 114 is located in the fluid circuit 113 and may be positioned at any suitable location between the exhaust muffler 136 and the exhaust port 108, and is configured to extract heat, or absorb energy, from the exhaust gases 110, as shown in FIG. 2. The first heat exchanger 114 is connected to the first turbine 118 using a first conduit 138. The first conduit 138 is configured to allow passage of the working fluid from the first heat exchanger 114 to the first turbine 118. The first turbine 118 is located in the fluid circuit 113 and may be positioned between the first heat exchanger 114 and the second heat exchanger 116.

[0021] In the illustrated embodiment the first turbine 118 is configured to drive the first compressor 120. The first turbine 118 may be fluidly connected to the second heat exchanger 116 via a second conduit 140. The second conduit 140 may be configured to allow passage of the working fluid from the first turbine 118 to the second heat exchanger 116. The second heat exchanger 116 is located in the fluid circuit 113 and may be positioned between the first heat exchanger 114 and the first turbine 118. The second heat exchanger 116 may be configured to extract heat from, or cool, the working fluid circulating in the fluid circuit 113 of the energy recovery system 112. A third conduit 142 enables the working fluid to flow from the second heat exchanger 116 to the pump 144. A fourth conduit 146 allows the working fluid to flow from the pump 144 to the first heat exchanger 114. The pump 116 may circulate the working fluid around the fluid circuit 113 continuously in this manner. As one of skill in the art will appreciate, the first conduit 138, second conduit 140, third conduit 142 and fourth conduit 146 may be any type of fluid conveying means known in the art.

[0022] The first turbine 118 is configured to drive the first compressor 120 to provide compressed intake air (“boost air”) to the engine 100. An air intake system 122 may be configured to provide fresh intake air to the first compressor 120, which the first compressor 120 may compress prior to directing it towards the engine 100. As one of skill in the art will appreciate, the air intake system 122 may be any type of air introducing system known in the art. The air intake system 122 may be adapted to use various filters or filtering techniques to provide fresh intake air from the atmosphere to the first compressor 120. In various other embodiments the first compressor 120 may be any type of compressor that can be used to provide compressed intake air to an internal combustion engine such as a rotary compressor, reciprocating compressor, a centrifugal compressor, an axial compressor and the like.

[0023] The first turbine 118 may alternatively be configured to drive a cooling system 126 or a compressor for compressing exhaust gases from the engine 100. However, as discussed below, preferably further turbines are provided for driving the compressors and cooling system. In some embodiments a plurality of turbines may be driven by the fluid circuit 113; a first turbine 118 for driving the first compressor 120 for compressing intake air, a second turbine for driving a cooling system, a third turbine for driving a compressor for compressing the intake air yet further and/or an exhaust gas turbine for driving an exhaust gas compressor for compressing exhaust gases.

[0024] In an embodiment a second turbine 124 may be connected in parallel with the first turbine 118 as shown in FIG. 3. The second turbine 124 may be positioned between the first heat exchanger 114 and the second heat exchanger 116 and may be driven by the working fluid from the first heat exchanger 114. The second turbine 124 may also run as per an organic Rankine cycle and may be configured to power the cooling system 126 present in the engine system 90. The first turbine 118 and the second turbine 124 may be any type of turbine such as radial turbine, axial turbine, Pelton turbine, Francis turbine, Kaplan turbine, Turgo turbine or the like. The cooling system 126 may be a cooling fan. The cooling fan may be a centrifugal fan or a mixed flow fan or a cross flow fan or an axial fan. In alternative embodiments the cooling system 126 may receive power from the first turbine 118.

[0025] A valve 128 may be provided between the first turbine 118 and the first heat exchanger 114. A valve 128 may be provided between the second turbine 124 and the first heat exchanger 114. The valves 128 may be expansion valves and may be configured to apportion the organic fluid flow between the first turbine 118 and the second turbine 124. The valves 128 may be controlled automatically or manually via an engine control unit or the like.

[0026] The engine system 90 may also comprise a charge air cooler 130. The charge air cooler 130 may be provided between the engine 100 and the first compressor 120. The charge air cooler 130 may be configured to cool the pressurized air from the first compressor 120 before it is introduced into the combustion chamber 102. The cooling system 126 may increase the air flow over the charge air cooler 130 to increase the rate of cooling of the intake gas. Further, the engine system 90 may also consist of an exhaust gas aftertreatment system 132. The exhaust gas aftertreatment system 132 may be provided between the engine 100 and the first heat exchanger 114. The exhaust gas aftertreatment system 132 may be configured to reduce the amount of harmful pollutants in the stream of exhaust gases 110 exiting the engine 100.

[0027] In yet another embodiment, a third turbine 150 may be positioned upstream of the first heat exchanger 114, as shown in FIG. 4. The third turbine 150 is configured to be driven by the stream of exhaust gases 110 from the engine 100. In alternate embodiments, the third turbine 150 may be driven by the kinetic energy of the exhaust stream. Further, the third turbine 150 is configured to drive a second compressor 148, which may be located upstream of the first compressor 120. On being driven by the third turbine 150, the second compressor 148 compresses fresh air from the air intake system 122 and passes the compressed air to the first compressor 120.

[0028] In yet another embodiment of the present disclosure, as shown in FIG. 5, the second compressor 148 may be located downstream of the first compressor 120. The third turbine 150 may drive the second compressor 148 such that the second compressor 148 is selectively operated to further compress the compressed air received from the first compressor 120.

[0029] In yet another embodiment of the present disclosure, the third turbine 150 may be positioned upstream of the first heat exchanger 114, as shown in FIG. 6. The third turbine 150 is configured to be driven by the stream of exhaust gases 110 from the engine 100 and drive a second compressor 148 for compressing fresh air supplied to the engine 100. Further, in the embodiment illustrated in FIG. 6, the first turbine 118 in the fluid circuit 113, which may be referred to as an exhaust gas turbine, drives the first compressor 120, which may be referred to as an exhaust gas compressor, to compress the hot exhaust gasses 110. This compression of the hot exhaust gases 110 reduces the back pressure and improves engine 100 operation.

[0030] During operation, the heat or thermal energy of the hot exhaust gases 110 exiting the combustion chamber 102 may be transferred to the working fluid of the fluid circuit 113 via the first heat exchanger 114, as shown in FIG. 3. The working fluid in the first heat exchanger 114 may then evaporate and be directed to the first turbine 118. The working fluid may expand across the first turbine 118, thereby driving the first turbine and first compressor 120. The intake air may thereby be compressed. The working fluid from the first turbine 118 may then be directed to the second heat exchanger 116, in which it condenses by changing its phase from gas to liquid by giving up its latent heat. This latent heat of the working fluid is extracted by the second heat exchanger 116 and may be directed to the local environment. The cooling system 126 may drive atmospheric air over the second heat exchanger 116 to increase the rate of cooling of, or heat extraction from, the working fluid via the second heat exchanger 116.

[0031] When the piston 104 reaches its lowest point of travel (known as bottom dead center), air/air-fuel mixture is forced into the combustion chamber 102 from an air intake system 122 using the first compressor 120 and, if present, the second compressor 148. The pressurized air/air-fuel mixture is forced into the combustion chamber 102 using an inlet pipe 134 through the intake port 106. In various other embodiments the air intake system 122 may be any different type of air introducing system such as an air intake manifold, a carburetor, etc. Further, the air intake system 122 may include air filters, purifiers, etc. to refine the fresh air to be introduced to facilitate removal of the unwanted elements and particulate matter for advanced combustion.

[0032] The compression stroke begins and the piston 104 moves upward and the intake port 106 is closed, thus preventing any backflow of the newly received charge through the intake port 106. As the piston 104 continues toward top dead center, the air/fuel mixture is compressed in preparation for the next power stroke. The cam (not shown) closes exhaust port 108 during this part of the cycle in order to maintain pressure during the compression stroke. When the piston 104 reaches top dead center, the cycle begins again. The exhaust port 108 opens once during each power stroke, thereby enabling the exhaust gases 110 to exit and drive the first turbine 118.

[0033] During operation of the engine 100, care should be taken to facilitate smooth functioning of the energy recovery system 112. FIG. 7 illustrates an exemplary method 700 used by engine 100 for the purpose of turbocharging an engine 100 using the energy recovery system 112. FIG. 7 will be discussed in more detail below to further illustrate the disclosed concepts.

Industrial Applicability [0034] Power producing units such as diesel engines, gasoline engines, and gaseous fuel-powered engines require an optimum amount of air/air-fuel mixture to produce high power at a high efficiency. In order to maximize the power output generated by this combustion process without injecting more fuel into the engine, the engine is often equipped with an exhaust manifold in fluid communication with a turbocharger i.e. an air induction system. A conventional turbocharger uses the exhaust stream velocity to drive a compressor configured to introduce more air into the combustion chamber. However, the high temperature of the exhaust gases is left unutilized and exposed to the atmosphere, which may not be desired. The method of operation 700 of the disclosed energy recovery system 112 will now be described in detail with reference to FIG. 7.

[0035] As seen in FIG. 3, the energy recovery system 112 uses an organic Rankine cycle in the fluid circuit 113 to facilitate providing compressed intake air to the engine 100 by utilizing the thermal energy of the exhaust gases 110. The energy recovery system 112 comprises a first heat exchanger 114 transferring energy of the hot exhaust gases 110 to evaporate the working fluid circulating in the first heat exchanger 114 (Step 702). This high energy working fluid is then passed on to the first turbine 118. The high energy working fluid transfers energy to the blades of the first turbine 118 thereby driving it (Step 704). The first turbine 118 drives the first compressor 120 which forces pressurized intake air into the combustion chamber 102 to provide compressed air to the engine 100 (Step 706). The organic fluid exiting the first turbine 118 is passed through a second heat exchanger 116 where the organic fluid gives up its latent heat and condenses (Step 708). The energy recovery system 112 thereby efficiently uses the heat enthalpy of the exhaust gases 110. Furthermore, the enthalpy of the exhaust gases 110 can still be utilized to produce some output work using another turbine.

[0036] In another aspect of the present disclosure a second turbine 124 is connected in parallel with the first turbine 118. The second turbine 124 may be configured to cool and increase the heat rejected by the second heat exchanger 116 during operation of the engine 100.

[0037] In yet another aspect of the present disclosure, the third turbine 150 is connected upstream of the first heat exchanger 114 as shown in FIG. 4 and FIG. 5. The third turbine 114 is driven by the enthalpy of the exhaust stream from the engine 100 and drives a second compressor 148. The fresh air received from the air intake system 122 is compressed by the second compressor 148. This compressed air/ boost air is then passed on to the first compressor 120 as shown in FIG. 4.

[0038] In yet another aspect of the present disclosure, as shown in FIG. 5, the second compressor 148 receives the compressed air/ boost air from the first compressor 120. When the third turbine 150 is driven by the exhaust stream it drives the second compressor 148. This causes the second compressor 148 to further compress the boost air received from the first compressor 120. This compressed boost air is then passed on to the engine 100. This provides for a multi stage compression to turbocharge the engine 100.

[0039] In yet another aspect of the present disclosure, as shown in FIG. 6, the second compressor 148 is driven by the third turbine 150, compresses the fresh air received from the air intake system 122 and provides the compressed air to the engine 100. Further, the first compressor 120 or exhaust gas compressor, which is driven by the first turbine 118, compresses the exhaust stream from the engine 100. This compression of the exhaust stream reduces the back pressure of the exhaust gas on the engine 100 and thereby improves the efficiency of the operation of the engine 100.

[0040] While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof

Claims

1. An energy recovery system for an internal combustion engine comprising: a first heat exchanger configured to transfer heat from an exhaust gas stream of the engine to a working fluid circulated in a fluid circuit; a first turbine located in the fluid circuit and configured to be driven by the heated working fluid from the first heat exchanger, the first turbine being configured to drive at least one of: a first compressor for compressing intake air to the engine; an exhaust gas compressor for compressing exhaust gas from the engine; and a cooling system; and a second heat exchanger located in the fluid circuit positioned downstream of the first turbine and upstream of the first heat exchanger, the second heat exchanger being configured to extract heat from the working fluid.

2. The energy recovery system as claimed in claim 1 further comprising a valve positioned between the first heat exchanger and the first turbine.

3. The energy recovery system as claimed in claim 1 or claim 2 further comprising a second turbine driven by the working fluid from the first heat exchanger, the second turbine being configured to power a cooling system.

4. The energy recovery system as claimed in claim 3, wherein the first turbine and the second turbine are connected in parallel in the fluid circuit.

5. The energy recovery system as claimed in claim 3 or claim 4, wherein the cooling system comprises a fan.

6. The energy recovery system as claimed in any one of claims 3 to 5, wherein the cooling system is configured to extract heat from the second heat exchanger such that the second heat exchanger extracts heat from the working fluid.

7. The energy recovery system as claimed in any one of the preceding claims, further comprising a third turbine positioned upstream of the first heat exchanger, the third turbine configured to be driven by the exhaust stream of the internal combustion engine and configured to drive a second compressor for compressing intake air before or after the first compressor.

8. An engine system comprising an internal combustion engine, an energy recovery system as claimed in any one of the preceding claims and at least one of: a first compressor arranged to compress intake air to the engine; an exhaust gas compressor arranged to compress exhaust gas from the engine; and a cooling system.

9. The engine system as claimed in claim 8 further comprising a charge air cooler configured to extract heat from the intake air.

10. The engine system as claimed in claim 8 or claim 9 further comprising an exhaust gas aftertreatment system positioned between the engine and the first heat exchanger.

11. A method of operating an engine system comprising: transferring heat from an exhaust stream of the engine to a working fluid in a fluid circuit using a first heat exchanger; driving a first turbine by the working fluid from the first heat exchanger, such that the first turbine drives at least one of: a first compressor which compresses intake air to the engine; an exhaust gas compressor which compresses exhaust gas from the engine; and a cooling system; and extracting energy from the working fluid discharged by the first turbine in a second heat exchanger positioned between the first turbine and the first heat exchanger in the fluid circuit.

12. The method as claimed in claim 11, the method further comprising driving a second turbine by the working fluid from the first heat exchanger, the second turbine configured to provide power to the cooling system.

13. The method as claimed in claim 11 or claim 12, wherein the cooling system is configured to extract heat from the second heat exchanger such that the second heat exchanger extracts heat from the working fluid.

14. The method as claimed in any one of claims 11 to 13, further comprising driving a third turbine by the exhaust stream from the internal combustion engine, such that the third turbine drives a second compressor to compress intake air before or after the first compressor.