Apparatus and method for improving efficiency of propulsion systems

Abstract

A system (100) and a method (400) for improving efficiency of a combustion engine (102) are disclosed. The combustion engine (102) includes a combustion chamber (112), a turbocharger (114), and a scavenging air receiver (116). The scavenging air receiver (116) is configured to receive a compressed air flow (118) from the turbocharger (114) and supply a first portion (120A) of the compressed air flow (118) to the combustion chamber (112). An air lubrication system (104) is connected or connectable to the scavenging air receiver (116) to receive a second portion (120B) of the compressed air flow (118) from the scavenging air receiver (116). A heat exchanger (122) of a steam generation unit (106) is fluidically connected or connectable to an exhaust discharge outlet (230) of the turbocharger (114) to utilize thermal energy of the exhaust gas (108) to heat a fluid used in the steam generation unit (106).

Description

APPARATUS AND METHOD FOR IMPROVING EFFICIENCY OF PROPULSION SYSTEMSTECHNICAL FIELD

[0001] The present disclosure generally relates to combustion engines and, more particularly, to a system and a method for improving efficiency of combustion engines by fluidically connecting an air lubrication system with a steam generation unit.BACKGROUND

[0002] Diesel engines serve as integral power sources across a wide array of applications, notably finding use in the maritime sector for propulsion. Continuous efforts have been dedicated to improving the performance of diesel engines by maximizing the utility of waste heat generated during their operation. One common approach involves the utilization of exhaust gas from the diesel engine for various purposes. Traditionally, turbochargers harness the energy from exhaust gases, driving a compressor to enhance air intake for combustion. This method is fundamental in elevating the overall efficiency of diesel engines, a critical consideration in the constantly evolving landscape of industrial and transportation needs.

[0003] In the maritime domain, where diesel engines play a crucial role, vessels present a myriad of operational challenges. These challenges span from addressing frictional resistance to fulfilling intricate requirements such as air lubrication for optimal hull performance. Recognizing these needs, there is an imperative to explore effective means of utilizing exhaust gases and other engine-related waste heat. The overarching goal is not only to augment the efficiency of diesel engines but also to proactively address environmental factors. This strategic integration of waste heat utilization stands as a pivotal avenue for achieving enhanced overall efficiency while aligning with sustainability objectives.SUMMARY

[0004] Examples of the present disclosure as described herein aim to address one or more of the problems described hereinabove. According to one aspect, there is provided a system comprising a combustion engine, an air lubrication system, and a steam generation unit. The air lubrication system is a system designed to reduce the frictional resistance of the vessel in the water (e.g.,seawater) using the compressed air flow. The air lubrication system injects the compressed air flow into the wet surface of a hull of the vessel. The air lubrication system works on the principle of trapping a layer of air bubbles beneath the hull. The air bubble distribution across the hull surface reduces the resistance working on the hull, creating energy-saving effects. The combustion engine has a combustion chamber, at least one turbocharger, and a scavenging air receiver. The at least one turbocharger includes an inlet fluidically connected or connectable to the combustion chamber to receive an exhaust gas generated in the combustion chamber. The scavenging air receiver is configured, at least in part, to receive a compressed air flow from the at least one turbocharger and supply a first portion of the compressed air flow to the combustion chamber. Further, the air lubrication system is connected or connectable to the scavenging air receiver to receive a second portion of the compressed air flow from the scavenging air receiver. Furthermore, the steam generation unit is provided with a heat exchanger. The heat exchanger is fluidically connected or connectable to an exhaust discharge outlet of the at least one turbocharger to receive the exhaust gas. The heat exchanger is adapted to utilize thermal energy of the exhaust gas to heat a fluid used in the steam generation unit. Advantageously, the combination of the combustion engine, the air lubrication system, and the steam generation unit is beneficial for utilizing waste heat of the exhaust gas of the combustion engine, increasing the electrical power generation capacity of the vessel, and reducing the frictional resistance of a hull of the vessel in the water.

[0005] In an aspect of the system, the exhaust gas is generated from a combustion of methanol or ethanol with the first portion of the compressed air flow. Methanol or ethanol, used as fuel in the combustion engine, in combination with the air lubrication system and the steam generation unit, improves thermal efficiency and maintains the engine temperature below the designed value. The methanol or ethanol can be used as fuel in the combustion engine due to bypassing the compressed air flow to the air lubrication system and not providing the complete compressed air flow to the combustion engine.

[0006] In an aspect of the system, the first portion is about 80% to 90% of the compressed air flow and the second portion is about 10% to 20% of the compressed air flow. Such a distribution of the compressed air flow maintains engine temperature below its designed value and effectively utilizes the thermal energy of waste heat of the exhaust gas in the steam generation unit and provides the compressed air flow for the air lubrication system.

[0007] In an aspect of the system, the combustion engine, the air lubrication system, and the steam generation unit form an integrated system. Advantageously, the integrated system allows the methanol to be used as fuel in the combustion engine. The methanol maintains the engine temperature below its designed value and the thermal energy of the methanol can be effectively utilized in the steam generation unit.

[0008] In an aspect of the system, the steam generation unit includes a boiler. The boiler has an economizer and a superheater, and the heat exchanger is at least one of the economizer and the superheater. Advantageously, the economizer and the superheater utilize the waste heat of the exhaust gas of the combustion engine to heat the fluid being supplied to the steam turbine for the generation of electric power. Consequently, the thermal energy required to heat the fluid in the boiler is reduced, which in turn reduces the cost of generation of electric power for the vessel.

[0009] In an aspect of the system, a vessel includes the system. Advantageously, the steam generation unit of the system increases the electrical power generation capacity of the vessel, and the air lubrication system reduces the frictional resistance of the vessel in the water.

[0010] In an aspect, a method is disclosed. The method provides a combustion engine including a combustion chamber, at least one turbocharger, and a scavenging air receiver. The method also provides an air lubrication system and a steam generation unit. Each of the air lubrication system and the steam generation unit is fluidically connected to the combustion engine. The method further includes receiving, by the at least one turbocharger, an exhaust gas from the combustion chamber. Subsequently, the method includes supplying, from the at least one turbocharger, the exhaust gas to a heat exchanger of the steam generation unit and compressed air flow to the scavenging air receiver. The heat exchanger is adapted to utilize the thermal energy of the exhaust gas to heat fluid used in the steam generation unit. Furthermore, the method includes supplying, by the scavenging air receiver, a first portion of the compressed air flow to the combustion chamber and a second portion of the compressed airflow to the air lubrication system. Advantageously, the combination of the combustion engine, the air lubrication system, and the steam generation unit is beneficial for utilizing waste heat of the exhaust gas of the combustion engine, increasing the electrical power generation capacity of the vessel, and reducing the frictional resistance of a hull of the vessel in the water.

[0011] In an aspect of the method, the exhaust gas is generated from a combustion of methanol or ethanol with the first portion of the compressed air flow. Methanol or ethanol, used as fuel in the combustion engine, in combination with the air lubrication system and the steam generation unit, improves thermal efficiency and maintains the engine temperature below the designed value. The methanol or ethanol can be used as fuel in the combustion engine due to bypassing the compressed air flow to the air lubrication system and not providing the complete compressed air flow to the combustion engine.

[0012] In an aspect of the method, the first portion is about 80% to 90% of the compressed air flow and the second portion is about 10% to 20% of the compressed air flow. Such a distribution of the compressed air flow maintains engine temperature below its designed value and effectively utilizes the thermal energy of waste heat of the exhaust gas in the steam generation unit.

[0013] In an aspect of the method, the combustion engine, the air lubrication system, and the steam generation unit form an integrated system. Advantageously, the integrated system allows the methanol to be used as fuel in the combustion engine. The methanol maintains the engine temperature below its designed value and the thermal energy of the methanol can be effectively utilized in the steam generation unit.

[0014] In an aspect of the method, the steam generation unit includes a boiler. The boiler has an economizer and a superheater, and the heat exchanger is at least one of the economizer and the superheater. Advantageously, the economizer and the superheater utilize the waste heat of the exhaust gas of the combustion engine to heat the fluid being supplied to the steam turbine for the generation of electric power. Consequently, the thermal energy required to heat the fluid in the boiler is reduced, which in turn reduces the cost of generation of electric power for the vessel.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other features and advantages of the present disclosure will become readily apparent to those skilled in the art by the following detailed description of exemplary embodiments thereof with reference to the attached drawings, in which:

[0016] Figure 1 illustrates a block diagram representation of a system related to various embodiments of the present disclosure;

[0017] Figure 2 illustrates a schematic representation of the system, in accordance with one embodiment of the present disclosure;

[0018] Figure 3 illustrates a schematic representation of the system, in accordance with another embodiment of the present disclosure; and

[0019] Figure 4 illustrates a flow diagram of a method for improving efficiency of a combustion engine, in accordance with an embodiment of the present disclosure.DETAILED DESCRIPTION

[0020] Various exemplary embodiments and details are described hereinafter, with reference to the figures when relevant. It should be noted that the figures may or may not be drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the disclosure or as a limitation on the scope of the disclosure. In addition, an illustrated embodiment does not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated, or if not so explicitly described.

[0021] The figures are schematic and simplified for clarity, and they merely show details which aid in understanding the disclosure, while other details have been left out. Throughout, the same reference numerals are used for identical or corresponding parts.

[0022] Various embodiments of the present disclosure relate to a system and a method for improving efficiency of combustion engines installed in marine vehicles, such as a vessel. The system mainly includes a combustion engine, an air lubrication system, and a steam generation unit. The air lubrication system and the steam generation unit are fluidically connected or connectable to the combustion engine. The air lubrication system is configured to receive compressed air from the combustion engine and the steam generation unit is configured to utilize thermal energy of an exhaust gas to heat a fluid (e.g., water, steam, etc.) used in the steam generation unit. The fuel used in the combustion process is methanol or ethanol. The combinationof the air lubrication system and the steam generation unit by means of the combustion engine using combustion fuels such as methanol improves its efficiency.

[0023] Various example embodiments of the present disclosure are described hereinafter with reference to Figure 1 to Figure 4.

[0024] Figure 1 illustrates a block diagram representation of a system 100 related to various embodiments of the present disclosure. The system 100 mainly includes a combustion engine 102, an air lubrication system 104, and a steam generation unit 106. The air lubrication system 104 and the steam generation unit 106 are fluidically connected or connectable to the combustion engine 102. The air lubrication system 104 receives compressed air from the combustion engine 102 that is generated by utilizing a pressure energy of an exhaust gas 108 produced during a combustion process in the combustion engine 102, while the steam generation unit 106 utilizes thermal energy of the exhaust gas 108 to heat a fluid (e.g., water, steam, etc.) that flows in the steam generation unit 106. In the shown example of Figure 1 , the system 100 including the combustion engine 102, the air lubrication system 104, and the steam generation unit 106 is a part of a marine vehicle including, but not limited to vessels, ships, barges, boats, etc.

[0025] The combustion engine 102 primarily includes a piston-cylinder assembly 110 having a combustion chamber 112, at least one turbocharger 114 (also referred to as “turbocharger (114)”) fluidically connected or connectable to the combustion chamber 112, and a scavenging air receiver 116 fluidically connected or connectable to the turbocharger 114. The turbocharger 114 receives the exhaust gas 108 from the combustion chamber 112 and delivers a compressed air flow 118 to the scavenging air receiver 116. The scavenging air receiver 116 supplies a first portion 120A of the compressed air flow 118 to the combustion chamber 112 of the piston-cylinder assembly 110 and a second portion 120B of the compressed air flow 118 to the air lubrication system 104. The distribution of the compressed air flow 118 into the first portion 120A and the second portion 120B is dependent upon several factors, such as but not limited to, (a) overheating of the piston-cylinder assembly 110, (b) an exergy of the exhaust gas 108 supplied to the steam generation unit 106, and (c) type of fuel {e.g., methanol, ethanol, etc.) used for combustion.

[0026] The air lubrication system 104 is connected or connectable to the scavenging air receiver 116 to receive the second portion 120B of the compressed air flow 118. The second portion 120B of the compressed air flow 118 can be utilized for one or more purposes. I n a non-limiting example,the second portion 120B of the compressed air flow 118 can be utilized for injecting into a wetted surface of a hull of the vessel to reduce the frictional resistance of the hull in the water (e.g., seawater).

[0027] Further, the steam generation unit 106 is fluidically connected or connectable to the turbocharger 114 to receive the exhaust gas 108. A heat exchanger 122 of the steam generation unit 106 utilizes the thermal energy of the exhaust gas 108 to heat the fluid used in the steam generation unit 106. Overall, the system 100 is designed to combine the combustion engine 102, the air lubrication system 104, and the steam generation unit 106 at least for (a) utilizing waste heat of the exhaust gas 108 of the combustion engine 102, (b) improving efficiency of the combustion engine 102, and (c) improving the overall performance of the vessel.

[0028] Figure 2 illustrates a schematic representation of the system 100, in accordance with one embodiment of the present disclosure. As shown, the combustion engine 102 includes a plurality of components and devices. The piston-cylinder assembly 110 of the combustion engine 102 works on the principle of converting the chemical energy of the fuel into mechanical energy. The mechanical energy of the piston-cylinder assembly 110 disclosed herein is configured to operate marine vehicles (e.g., vessels, ships, barges, boats, etc.), without limiting the scope of the invention. The piston-cylinder assembly 110 can embody different variants of a diesel engine, such as a two-stroke diesel engine, a four-stroke diesel engine, a single-cylinder diesel engine, a multi-cylinder diesel engine, and the like.

[0029] The piston-cylinder assembly 110 mainly includes a cylinder 202, a piston 204, a cylinder liner (not shown) inserted into the cylinder 202 providing a smooth sliding surface for reciprocating motion of the piston 204, a cylinder head 206 mounted on the cylinder 202, the combustion chamber 112 located in the cylinder head 206, a fuel injection system 208, an inlet manifold 210, an exhaust manifold 212, and the like. During the suction stroke of the piston 204, the first portion 120A of the compressed air flow 118 enters the combustion chamber 112 through the inlet manifold 210. Subsequently, during the compression stroke, the piston 204 compresses the first portion 120Aof the compressed airflow 118, and at the end of this stroke, the fuel injection system 208 injects the fuel. Consequently, the fuel ignites due to the compression of the first portion 120A of the compressed air flow 118, and an expansion stroke (i.e. , power stroke) of the piston 204 occurs. The exhaust gas 108 is then expelled during the exhaust stroke and discharged into the exhaust manifold 212. The geometrical configuration and operating aspects of these componentsare well-known in the art and are not extensively discussed here for the sake of brevity. Further, it should be noted that the piston-cylinder assembly 110 is depicted with specific components, those skilled in the art would appreciate that the piston-cylinder assembly 110 includes additional components that may not be relevant for explaining the present invention and are hence omitted from the depiction and description.

[0030] In a specific embodiment of the invention, the fuel used in the combustion process is at least one of methanol or ethanol. The exhaust gas 108 is generated from the combustion of methanol or ethanol with the first portion 120A of the compressed air flow 118. Methanol or ethanol, used as fuel in the combustion engine 102, in combination with the air lubrication system 104 and the steam generation unit 106, offers advantages over conventional fuels (e.g., diesel). The methanol or ethanol can be used as fuel in the combustion engine 102 due to bypassing the compressed air flow 118 to the air lubrication system 104 and not providing the complete compressed air flow 118 to the combustion engine 102. In a non-limiting example, for the same engine power, a higher volume of methanol is needed for combustion than that of conventional fuels. As a result, the temperature of the exhaust gas 108 is comparatively lower. Further, by appropriate distribution of the compressed air flow 118 into the first portion 120A and the second portion 120B, the thermal exergy of the exhaust gas 108 supplied to the steam generation unit 106 can be enhanced. In other words, supplying the second portion 120B of the compressed air flow 118 to the air lubrication system 104 results in the generation of the exhaust gas 108 with enhanced thermal energy capable of producing steam in the steam generation unit 106. As the second portion 120B of the compressed air flow 118 is bypassed for air lubrication system 104, the thermal energy of the exhaust gas 108 can be used for the generation of the steam.

[0031] Further, an exhaust gas receiver 214 is fluidically connected or connectable to the exhaust manifold 212. The exhaust gas receiver 214, as disclosed herein, may constitute an adiabatic chamber designed to store the exhaust gas 108 at a predetermined pressure. The design of the exhaust gas receiver 214 is dependent, at least in part, upon the operating capacity of the pistoncylinder assembly 110 that generates the exhaust gas 108 during the combustion process.

[0032] In this embodiment of the invention, the exhaust gas receiver 214 is fluidically connected with the scavenging air receiver 116 via a flow path 216. At least the turbocharger 114, an air cooler 218, and a water mist catcher 220 are installed along the flow path 216.

[0033] In the illustrated configuration, the turbocharger 114 is fluidically connected or connectable to the exhaust gas receiver 214 to receive the exhaust gas 108 generated during the combustion process of the piston-cylinder assembly 110. In another configuration, the turbocharger 114 may be fluidically connected or connectable directly to the exhaust manifold 212, and the exhaust gas receiver 214 may not be needed. Herein, the turbocharger 114 is depicted as an integral part of the combustion engine 102. However, in another representative example, the turbocharger 114 can be configured as an individual device rather than being a part of the combustion engine 102, without limiting the scope of the invention.

[0034] In the illustrated example representation, the turbocharger 114 mainly includes a rotor 222, a turbine 224 secured on one side of the rotor 222, and a compressor 226 secured on another side of the rotor 222. The turbine 224 includes an inlet 228 for receiving the exhaust gas 108 from the exhaust gas receiver 214. The exhaust gas 108 spins the turbine 224 to rotate the rotor 222 and discharges from an exhaust discharge outlet 230 to the heat exchanger 122 of the steam generation unit 106. Based on the type of the turbine 224 (e.g., an axial flow turbine, a radial flow turbine, and a mixed flow turbine), the exhaust gas 108 may enter and leave axially, radially, etc., from the turbine 224. As the compressor 226 is secured on another side of the rotor 222, the rotor 222 rotates the compressor 226. The compressor 226 is configured to receive atmospheric air and deliver compressed air through the rotary motion of the rotor 222. Without loss of generality, the compressor 226 used herein can be a positive displacement compressor (e.g., reciprocating compressor) or continuous flow compressor (e.g., centrifugal compressor). It may be noted that the turbocharger 114 is shown to have included the above-stated parts, however, those skilled in the art would appreciate that the turbocharger 114 includes other parts that may not be relevant for explaining the present invention and hence are not shown and described.

[0035] In a non-limiting example, the compressed air flow 118 discharged from the compressor 226 is a compressed heated air, requiring cooling and drying before being supplied to the combustion chamber 112 and the air lubrication system 104. In other words, the compressed air flow 118 supplied to the scavenging air receiver 116 needs to be scavenged air. The flow path 216 first cools and then removes moisture from the compressed air flow 118 before supplying it to the scavenging air receiver 116. Therefore, the flow path 216 is also referred to as a scavenging flow path. In the flow path 216, first, the air cooler 218 cools the compressed air flow 118 and then the water mist catcher 220 removes moisture therefrom. The geometrical configuration andoperating features of the one or more components used in the flow path 216 (i.e. , the air cooler 218 and water mist catcher 220) are well known in the art and therefore not extensively discussed herein for the sake of brevity. Additionally, it is noted that the flow path 216 may include additional components, such as a non-return valve, more than one air cooler, a flow control valve, etc. , which may not be pertinent to explaining the present invention and hence are not shown and described.

[0036] The scavenging air receiver 116 is configured to deliver the first portion 120A of the compressed air flow 118 to the combustion chamber 112 and the second portion 120B of the compressed air flow 118 to the air lubrication system 104. In an embodiment, the scavenging air receiver 116 incorporates a flow control valve (not shown) to control the flow of the first portion 120A of the compressed air flow 118 directed into the combustion chamber 112 and the second portion 120B of compressed air flow 118 received by the air lubrication system 104.

[0037] In a specific embodiment, the first portion 120A of the compressed air flow 118 supplied to the combustion chamber 112 is about 80% to 90% and the second portion 120B of the compressed air flow 118 supplied to the air lubrication system 104 is about 20% to 10% of the total compressed air flow 118. It is important to note that the teachings of the present disclosure offer benefits with any type of combustion fuel used in the diesel engine, however with methanol being used as a fuel in the combustion engine 102, the advantages are more pronounced. For instance, the engine temperature is maintained below its designed value with usage of methanol as combustion fuel, that works well with the reduced distribution of the compressed air flow 118 into the combustion engine 102 because of the second portion 120B of the compressed air flow 118 directed to the air lubrication system 104. Additionally, there is a considerable enhancement in the exergy of the exhaust gas 108 directed to the steam generation unit 106, leading to effective utilization of the thermal energy of waste heat of the exhaust gas 108 in the steam generation unit 106. In effect, the combination of the air lubrication system 104 and the steam generation unit 106 by means of the combustion engine 102 using methanol as a combustion fuel improves its fuel efficiency and thermal efficiency.

[0038] In the illustrated configuration, the second portion 120B of the compressed air flow 118 is directed to the air lubrication system 104 from the scavenging air receiver 116. Alternatively, in another configuration, the second portion 120B of the compressed air flow 118 can be bypassed from a fluidic connection between the air cooler 218 and the water mist catcher 220, without departing from the scope of the invention.

[0039] Herein, the air lubrication system 104 injects bypass scavenged air flow (i.e., the second portion 120B of the compressed airflow) into a turbulent fluid boundary layer of the wetted surface around the hull of the vessel 232. Injecting the second portion 120B of the compressed air flow prevents the formation of the turbulent layer which in turn reduces a shear force between the wetted surface around the hull and the water (e.g., seawater). Consequentially, the frictional resistance of the hull of the vessel 232 in the water reduces dramatically. The air lubrication system 104 may include one or more air discharge units (ADlls) 234 for releasing the second portion 120B of the compressed air flow outside of the hull 201 below the waterline of the vessel 232. The ADlls 234 can take the form of nozzles (e.g., convergent nozzles) for releasing the second portion 120B of the compressed air flow outside of the hull below the waterline of the vessel 232. The geometrical configuration and operating aspects of air lubrication system 104 are well-known in the art and therefore are not extensively discussed here for the sake of brevity.

[0040] Furthermore, the heat exchanger 122 of the steam generation unit 106 is fluidically connected or connectable to the exhaust discharge outlet 230 of the turbocharger 114 to receive the exhaust gas 108. The steam generation unit 106 disclosed herein can take the form of any device, unit, or plant involved in steam generation, such as a steam power plant. In the steam power plant, the thermal energy of the exhaust gas 108 can be utilized to heat the fluid (e.g., water, steam, etc.). The steam generation unit 106 includes a Rankine cycle including a boiler 236, a steam turbine 238, a condenser (not shown), and one or more pumps (not shown). The thermal energy of the exhaust gas 108 is transferred to the boiler 236, wherein the fluid (e.g., water, steam, etc.) is converted into a high-pressure gaseous state (steam) for supply to the steam turbine 238. The steam turbine 238 utilizes the pressure energy of the steam to drive a generator 240. Subsequent to passing through the steam turbine 238, the steam undergoes condensation in the condenser through the latent heat of the condensation. Further, the condensed water is fed in the boiler 236 through one or more pumps, and this cycle is repeated.

[0041] The boiler 236 of the steam generation unit 104 includes the heat exchanger 122 that converts the liquid state of the fluid (i.e., water) into the superheated fluid (i.e., superheated steam). The heat exchanger 122 can be at least one of an economizer 242 and a superheater 244.

[0042] In one embodiment of the invention, the heat exchanger 122 takes the form of the economizer 242. The economizer 242 harnesses the thermal energy of the exhaust gas 108 toelevate the temperature of the fluid present in the liquid state (i.e. , water). The water absorbs the thermal energy from the exhaust gas 108, and a phase change of water into the steam takes place through a latent heat of vaporization. The steam quality depends upon the thermal energy content in the exhaust gas 108. The economizer 242 can assume the configuration of either a parallel-flow heat exchanger or a counter-flow heat exchanger, with no restriction on the scope of the invention. Further, based on the heating capacity, both the parallel-flow heat exchanger and the counter-flow heat exchanger can be single-pass or multi-pass heat exchangers, without limiting the scope of the invention.

[0043] In another embodiment of the invention, the heat exchanger 122 is configured as the superheater 244. The superheater 244 utilizes the thermal energy of the exhaust gas 108 to heat the fluid present in the gaseous state (i.e., steam). The steam absorbs thermal energy from the exhaust gas 108, and the steam (e.g., saturated steam) is converted into superheated steam through a sensible heat transfer. However, the quality of the superheated steam is contingent upon the thermal energy content in the exhaust gas 108. The superheater 244 can assume the configuration of either a parallel-flow heat exchanger or a counter-flow heat exchanger, without limiting the scope of the invention. Further, based on the heating capacity, the parallel-flow heat exchanger and the counter-flow heat exchanger can be a single-pass or a multi-pass heat exchanger, without limiting the scope of the invention.

[0044] It is important to note that the combustion engine 102, the air lubrication system 104, and the steam generation unit 106, collectively, constitute an integrated system (i.e., the system 100). The integrated system demonstrates its efficacy not only in the vessel 232, but also in various other marine vehicles including, but not limited to ships, barges, boats, etc.

[0045] Figure 3 illustrates a schematic representation of the system 100, in accordance with another embodiment of the present disclosure. In this embodiment, as opposed to a single flow path, two distinct flow paths (i.e., a first flow path 302A and a second flow path 302B) are used between the exhaust gas receiver 214 and the scavenging air receiver 116. In other words, the exhaust gas receiver 214 is fluidically connected with the scavenging air receiver 116 via the first flow path 302A and the second flow path 302B. As shown, the first flow path 302A includes a first turbocharger 304A, a first air cooler 306A, and a first water mist catcher 308A. Likewise, the second flow path 302B includes a second turbocharger 304B, a second air cooler 306B, and a second water mist catcher 308B. The first turbocharger 304A includes a first turbine 310A drivenby a first part 312A of the exhaust gas 108 flowing from the exhaust gas receiver 214 and a first compressor 314A for generating a first part 316A of the compressed air flow 118. A first exhaust discharge outlet 318A of the first turbine 31 OA is f I uidical ly connected to the steam generation unit 106 and is adapted to supply the first part 312A of the exhaust gas 108. Further, the first air cooler 306A is configured to cool the first part 316A of the compressed air flow 118 and the first water mist catcher 308A is configured to remove moisture content in the first part 316A of the compressed airflow 118. Likewise, the second turbocharger 304B includes a second turbine 31 OB driven by a second part 312B of the exhaust gas 108 flowing from the exhaust gas receiver 214 and a second compressor 314B for generating a second part 316B of the compressed air flow 118. A second exhaust discharge outlet 318B of the second turbine 31 OB is fluidically connected to the steam generation unit 106 and is adapted to supply the second part 312B of the exhaust gas 108. The second air cooler 306B is configured to cool the second part 316B of the compressed air flow 118 and the second water mist catcher 308B is configured to remove moisture content in the second part 316B of the compressed air flow 118.

[0046] In one configuration, the first exhaust discharge outlet 318A can be fluidically connected or connectable to the economizer 242 to receive the first part 312A of the exhaust gas 108 for heating the fluid (e.g., water) present therein and the second exhaust discharge outlet 318B is fluidically connected or connectable to the superheater 244 to receive the second part 312B of the exhaust gas 108 for heating the fluid (e.g., steam) present therein. However, in another configuration, both the first exhaust discharge outlet 318A and the second exhaust discharge outlet 318B can be fluidically connected to the economizer 242 to receive the first part 312A and the second part 312B of the exhaust gas 108 respectively, for heating the fluid present in the economizer 242. Further, in yet another embodiment, both the first exhaust discharge outlet 318A and the second exhaust discharge outlet 318B are fluidically connected to the superheater 244 to receive the first part 312A and the second part 312B of the exhaust gas 108 respectively, for heating the fluid present in the superheater 244.

[0047] It is important to note that the first part 316A and the second part 316B are individually delivered to the scavenging air receiver 116 as the compressed air flow 118. The geometric configuration of the elements within the first flow path 302A and the second flow path 302B may be similar or different from the geometrical configuration of the components in the flow path 216 of the system 100, as previously described with reference to Figure 2. The geometric configuration is dependent upon various factors, such as but not limited to, the power generation capacity ofthe combustion engine 102, fuel used for the combustion, size of the vessel 232, the thermal energy of the exhaust gas 108 required to heat the fluid of the economizer 242 or the superheater 244 of the boiler 236. Nonetheless, the operating characteristics of the components within the first flow path 302A, the second flow path 302B, and the flow path 216 shall remain consistent.

[0048] Further, in yet another embodiment of the invention, more than two flow paths can be used between the exhaust gas receiver 214 and the scavenging air receiver 116 of the combustion engine 102. In such a configuration, at least one flow path may include a scrubber (not shown), an exhaust gas receiver (EGR) cooler (not shown), and a blower (not shown). The scrubber can receive the exhaust gas 108 from the exhaust gas receiver 214 to clean the exhaust gas 108, the EGR cooler to cool the exhaust gas 108, and one or more blowers to supply scavenging air to the scavenging air receiver 116. This flow path can be more beneficial where the requirement of the exhaust gas 108 is less and scavenging air is more.

[0049] Figure 4 illustrates a flow diagram of an example representation of a method 400 for improving the efficiency of the combustion engine 102, in accordance with an embodiment of the present disclosure. At step 402, the method 400 provides the combustion engine 102 including the combustion chamber 112, the turbocharger 114, and the scavenging air receiver 116. The turbocharger 114 is fluidically connected or connectable to the combustion chamber 112, and the scavenging air receiver 116 is fluidically connected or connectable to the turbocharger 114. The turbocharger 114 receives the exhaust gas 108 from the combustion chamber 112 and delivers the compressed air flow 118 to the scavenging air receiver 116. The geometrical configuration and operating aspects of the combustion engine 102 including the combustion chamber 112, the turbocharger 114, and the scavenging air receiver 116 are discussed in detail with reference to Figures 1 and 2, and therefore not reiterated here for the sake of brevity.

[0050] At step 404, the method 400 provides the air lubrication system 104 and the steam generation unit 106, each fluidically connected to the combustion engine 102. The air lubrication system 104 receives the second portion 120B of the compressed air flow 118 from the scavenging air receiver 116 of the combustion engine 102. The compressed air flow 118 is generated by utilizing the pressure energy of the exhaust gas 108 produced during the combustion process of the combustion chamber 112. Further, the steam generation unit 106 utilizes the thermal energy of the exhaust gas 108 to heat the fluid (e.g., water, steam, etc.) used in the steam generationunit 106. Overall, steps 402 and 404 combine the combustion engine 102, the air lubrication system 104, and the steam generation unit 106.

[0051] At step 406, the turbocharger 114 receives the exhaust gas 108 from the combustion chamber 112. In the example representation, the turbocharger 114 is fluidically connected or connectable to the exhaust gas receiver 214 to receive the exhaust gas 108 generated during the combustion process of the piston-cylinder assembly 110. In another configuration, the turbocharger 114 may be fluidically connected or connectable directly to the exhaust manifold 212, and the exhaust gas receiver 214 may not be needed. Upon receiving the exhaust gas 108, the turbine 224 operates the compressor 226, and step 408 occurs.

[0052] At step 408, the turbocharger 114 supplies the exhaust gas 108 to the heat exchanger 122 of the steam generation unit 106 and the compressed air flow 118 to the scavenging air receiver 116. The heat exchanger 122 (e.g., the economizer 242 or the superheater 244) utilizes the thermal energy of the exhaust gas 108 to heat the fluid (e.g., water, steam, etc.) used in the steam generation unit 106. In one embodiment, one flow path (i.e. , the flow path 216) is used to supply the exhaust gas 108 to the heat exchanger 122 of the steam generation unit 106 and the compressed air flow 118 to the scavenging air receiver 116, as shown in Figure 2. However, in another embodiment, instead of one flow path, two flow paths (i.e., the first flow path 302A and the second flow path 302B) are used to supply the exhaust gas 108 to the heat exchanger 122 of the steam generation unit 106 and the compressed air flow 118 to the scavenging air receiver 116, as shown in Figure 3.

[0053] At step 410, the scavenging air receiver 116 supplies the first portion 120A of the compressed air flow 118 to the combustion chamber 112 and the second portion 120B of the compressed air flow 118 to the air lubrication system 104. The distribution of the compressed air flow 118 into the first portion 120A and the second portion 120B is dependent upon several factors, such as but not limited to, (a) overheating of the piston-cylinder assembly 110, (b) the exergy of the exhaust gas 108 supplied to the steam generation unit 106, and (c) type of fuel (e.g., methanol, ethanol, etc.) used for combustion. In the specific embodiment, the first portion 120A of the compressed air flow 118 being supplied to the combustion chamber 112 is about 80% to 90% and the second portion 120B of the compressed air flow 118 being supplied to the air lubrication system 104 is about 20% to 10%. This distribution of the compressed air flow 118 facilitates several advantages of using methanol as a fuel in the combustion engine 102. For instance, theengine temperature is maintained below its designed value, and effective utilization of the thermal energy of waste heat of the exhaust gas 108 is possible in the steam generation unit 106. Overall, the combination of the air lubrication system 104 and the steam generation unit 106 by means of the combustion engine 102 using methanol as a combustion fuel improves its fuel efficiency and thermal efficiency.

[0054] Although features have been shown and described, it will be understood that they are not intended to limit the claimed disclosure, and it will be made obvious to those skilled in the art that various changes and modifications may be made without departing from the scope of the claimed disclosure. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. The claimed disclosure is intended to cover all alternatives, modifications, and equivalents.

Claims

CLAIMS1 . A system (100), comprising: a combustion engine (102) comprising: a combustion chamber (1 12); at least one turbocharger (114) comprising an inlet (228) fluidically connected or connectable to the combustion chamber (112) to receive an exhaust gas (108) generated in the combustion chamber (1 12); and a scavenging air receiver (116) configured, at least in part, to receive a compressed air flow (118) from the at least one turbocharger (114), and supply a first portion (120A) of the compressed air flow (1 18) to the combustion chamber (1 12); an air lubrication system (104) connected or connectable to the scavenging air receiver (116) to receive a second portion (120B) of the compressed air flow (1 18) from the scavenging air receiver (116); and a steam generation unit (106) comprising: a heat exchanger (122) fluidically connected or connectable to an exhaust discharge outlet (230) of the at least one turbocharger (114) to receive the exhaust gas (108), wherein the heat exchanger (122) is adapted to utilize thermal energy of the exhaust gas (108) to heat a fluid used in the steam generation unit (106).

2. The system (100) as claimed in claim 1 , wherein the exhaust gas (108) is generated from a combustion of methanol or ethanol with the first portion (120A) of the compressed air flow (118).

3. The system (100) as claimed in claims 1 or 2, wherein the first portion (120A) is about 80% to 90% of the compressed air flow (118) and the second portion (120B) is about 10% to 20% of the compressed air flow (118).

4. The system (100) as claimed in any one of the previous claims 1 to 3, wherein the combustion engine (102), the air lubrication system (104), and the steam generation unit (106) form an integrated system.

5. The system (100) as claimed in any one of the previous claims 1 to 4, wherein the steam generation unit (106) comprises a boiler (236), the boiler (236) comprising an economizer(242) and a superheater (244), and the heat exchanger (122) is at least one of the economizer(242) and the superheater (244).

6. A vessel (232) comprising the system (100) according to any one of previous claims 1 to 5.

7. A method (400), comprising: providing (402) a combustion engine (102) comprising a combustion chamber (1 12), at least one turbocharger (1 14), and a scavenging air receiver (116); providing (404) an air lubrication system (104) and a steam generation unit (106), each fluidically connected to the combustion engine (102); receiving (406), by the at least one turbocharger (1 14), an exhaust gas (108) from the combustion chamber (112); supplying (408), from the at least one turbocharger (114), the exhaust gas (108) to a heat exchanger (122) of the steam generation unit (106) and compressed air flow (1 18) to the scavenging air receiver (1 16), wherein the heat exchanger (122) is adapted to utilize the thermal energy of the exhaust gas (108) to heat fluid used in the steam generation unit (106); and supplying (410), by the scavenging air receiver (116), a first portion (120A) of the compressed air flow (118) to the combustion chamber (1 12) and a second portion (120B) of the compressed air flow (1 18) to the air lubrication system (104).

8. The method (400) as claimed in claim 7, wherein the exhaust gas (108) is generated from a combustion of methanol or ethanol with the first portion (120A) of the compressed air flow (118).

9. The method (400) as claimed in claims 7 or 8, wherein the first portion (120A) is about 80% to 90% of the compressed air flow (118) and the second portion (120B) is about 10% to 20% of the compressed air flow (1 18).

10. The method (400) as claimed in any one of claims 7 to 9, wherein the combustion engine (102), the air lubrication system (104), and the steam generation unit (106) form an integrated system.1 1 . The method (400) as claimed in any one of the claims 7 to 10, wherein the steam generation unit (106) comprises a boiler (236), the boiler (236) comprising an economizer (242) and asuperheater (244), and the heat exchanger (122) is at least one of the economizer (242) and the superheater (244).

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