A multi-fuel compression ignition engine

Abstract

The present disclosure envisages a multi-fuel compression ignition engine (100). The engine comprises, a port injection system (102) configured to inject a first fuel in an intake manifold (102A) of the engine (100), and a direct injection system (104) configured to inject a second fuel directly into a combustion chamber (110A) of the engine (100). The first fuel is selected from ethanol or blended ethanol and the second fuel is selected from Iso-octane or blended Iso-octane.

Description

[0001] A MULTI-FUEL COMPRESSION IGNITION ENGINE

[0002] FIELD

[0003] The present disclosure relates to the field of automobile engines. More particularly, the present disclosure relates to a multi-fuel compression ignition engine.

[0004] DEFINITIONS

[0005] As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicates otherwise.

[0006] Smoke density: The expression ‘Smoke density’ used in the context of this disclosure refers to but is not limited to, the concentration or opacity of visible particulate matter (PM), primarily soot, in the exhaust gases produced by an engine. It is a critical measure of the quality of combustion in the engine, particularly in diesel engines, where incomplete combustion can result in higher levels of visible smoke.

[0007] Blended ethanol: The expression ‘Blended ethanol’ used in the context of this disclosure refers to but is not limited to, a mixture of ethanol and conventional fossil fuels including gasoline.

[0008] BACKGROUND

[0009] The background information herein below relates to the present disclosure but is not necessarily prior art.

[0010] Over the decades, diesel engines have played a pivotal role in powering various modes of transportation and heavy machinery due to their efficiency and torque characteristics. However, their operation has been marred by the release of harmful pollutants into the environment, including nitrogen oxides (NOx), particulate matter (PM), carbon monoxide (CO), and hydrocarbons (HC). These emissions have significant adverse effects on both the environment and human health. Nitrogen oxides (NOx) contribute to the formation of smog and ground-level ozone, exacerbating respiratory issues such as asthma and increasing the risk of cardiovascular diseases. Particulate matter, consisting of tiny particles suspended in the air, penetrates deep into the lungs and enters the bloodstream, leading to respiratory problems, cardiovascular issues, and even premature death. Additionally, diesel emissions contain carcinogenic substances, posing long-term health risks such as cancer. Furthermore, the environmental impact extends beyond human health, affecting ecosystems, soil quality, and water sources. Addressing diesel engine emissions is imperative to mitigate these detrimental effects and pave the way for sustainable transportation and industrial practices. Hence, while diesel engines offer advantages in certain contexts, their environmental impact underscores the need for cleaner alternatives and effective emission reduction strategies.

[0011] To reduce the problems associated with conventional diesel engines, a dual-fuel engine was introduced. The dual fuel engine is an engine that runs on two different fuels. The dual fuel engines are known for reducing nitrogen oxide (NOx) and particulate matter (PM) emissions. However, the combinations of fuels have pre-ignition issues and produce higher knocking. Further, these engines have cold-start problems. Also, the combination of fuels still poses challenges for exhaust after-treatment systems and may require additional exhaust treatment technologies, which can increase the complexity and cost of the engine.

[0012] There is, therefore, felt need for an automobile engine which alleviates the aforementioned drawbacks.

[0013] OBJECTS

[0014] Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:

[0015] An object of the present disclosure is to provide a multi-fuel compression ignition engine.

[0016] Another object of the present disclosure is to provide a multi-fuel compression engine that facilitates controlled combustion of fuels and reduced engine knocking.

[0017] Yet another object of the present disclosure is to provide a multi-fuel compression engine that lowers emissions of harmful pollutants in the environment.

[0018] Still another object of the present disclosure is to provide a multi-fuel compression engine that prevents cold-start problems. Another object of the present disclosure is to provide a multi -fuel compression engine that has high efficiency.

[0019] Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

[0020] SUMMARY

[0021] The present disclosure relates to a multi -fuel compression ignition engine. The engine comprises a port injection system and a direct injection system. The port injection system is configured to inject a first fuel in an intake manifold of the engine. The direct injection system is configured to inject a second fuel directly into a combustion chamber of the engine. The first fuel is selected from ethanol or blended ethanol and the second fuel is selected from Iso-octane or blended Iso-octane.

[0022] The ratio of the first fuel to the second fuel injected in the combustion chamber is in the range 60:40 to 90: 10.

[0023] Blended ethanol includes ethanol in the range of 50% to 60% and fossil fuels in the range of 50% to 60%.

[0024] Blended Iso-octane includes Iso-octane in the range of 30% to 70% and N-heptane in the range of 30% to 70%.

[0025] The multi-fuel compression ignition engine includes a plurality of cylinders. Each cylinder encloses a crown piston.

[0026] The multi-fuel compression ignition engine includes a plurality of sensing units to detect predetermined parameters. The sensing units include an intake manifold pressure sensor, an air temperature sensor, a throttle position sensor, an oxygen sensor and an in-cylinder pressure sensor.

[0027] The multi-fuel compression ignition engine includes an engine control unit (ECU) configured to receive inputs from the plurality of sensing units, and generate control signals based on the received inputs to control the operation of the port injection system and the direct injection system. The port injection system and the direct injection system are in communication with the engine control unit to receive control signals to control the timing and the amount of fuel injected in the cylinders.

[0028] The multi-fuel compression ignition engine includes an exhaust after-treatment system having a microporous carbon filter unit.

[0029] In an embodiment, the multi-fuel compression ignition engine includes a preheater mechanism configured to heat the intake air or air-fuel mixture before the air-fuel mixture enters the combustion chamber.

[0030] Further, the present disclosure envisages a method of operating a multi-fuel compression ignition engine. The method includes the following steps:

[0031] - injecting a predetermined amount of a first fuel in the intake manifold by a port injection system;

[0032] - feeding a mixture of the first fuel and the air into the combustion chamber during the suction stroke of the engine through an intake valve;

[0033] - compressing the mixture of the first fuel and the air in the combustion chamber with a compression ratio ranging from 14: 1 to 20: 1;

[0034] - injecting a second fuel directly into the combustion chamber near the end of the compression stroke using a direct injection system to initiate compression ignition and a power stroke; and

[0035] - expelling the burnt gases from the combustion chamber during the exhaust stroke.

[0036] Further, the method of operating a multi-fuel compression ignition engine includes the step of preheating the air before the air enters the intake manifold and the combustion chamber.

[0037] Further, in an embodiment, the method of operating a multi -fuel compression ignition engine includes the following steps: sensing operating parameters of the engine using an intake manifold pressure sensor, an air temperature sensor, a throttle position sensor, an oxygen sensor and in-cylinder pressure sensor; sending sensed parameters to the engine control unit; determining optimum fuel injection time and the fuel amount by the engine control unit; and

[0038] - generating control signal by the engine control unit.

[0039] BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

[0040] The multi-fuel compression ignition engine, of the present disclosure will now be described with the help of the accompanying drawing, in which:

[0041] Figure 1 illustrates a sectional view of a cylinder of the multi-fuel compression ignition engine, in accordance with the present disclosure;

[0042] Figure 2 illustrates a sectional view of the crown piston of the multi-fuel compression ignition engine, in accordance with the present disclosure;

[0043] Figure 3 illustrates a block diagram of the operation of the multi-fuel compression ignition engine, in accordance with the present disclosure;

[0044] Figure 4A and Figure 4B illustrates a flow chart of the operation of the multi-fuel compression ignition engine, in accordance with the present disclosure; and

[0045] Figure 5 illustrates another flow chart of the operation of the multi-fuel compression ignition engine, in accordance with the present disclosure.

[0046] LIST OF REFERENCE NUMERALS

[0047] 100 multi -fuel compression ignition engine

[0048] 102 port injection system

[0049] 102A intake manifold 104 direct injection system

[0050] 106 inlet valve

[0051] 108 exhaust valve

[0052] 110 cylinder

[0053] 110A combustion chamber

[0054] 112 piston

[0055] 112A oil cavity

[0056] 112B crown

[0057] 112C piston rings

[0058] 112D piston grooves

[0059] 112E piston skirt

[0060] 112F boss

[0061] 112G gudgeon pin

[0062] 112H connecting rod

[0063] 114 sensing unit

[0064] 114A intake manifold pressure sensor

[0065] 114B air temperature sensor

[0066] 114C throttle position sensor

[0067] 114D oxygen sensor

[0068] 114E in-cylinder pressure sensor

[0069] 116 engine control unit 118 exhaust after-treatment system

[0070] 120 preheater mechanism

[0071] 200 method of operating the multi-fuel compression ignition engine

[0072] 400 another method of operating the multi-fuel compression ignition engine

[0073] DETAILED DESCRIPTION

[0074] The present disclosure relates to the field of automobile engines. More particularly, the present disclosure relates to a multi-fuel compression ignition engine.

[0075] Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details, are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

[0076] The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, steps, operations, elements, modules, units and / or components, but do not forbid the presence or addition of one or more other features, operations, elements, components, and / or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.

[0077] When an element is referred to as being "mounted on," "connected to," another element, it may be directly on, connected to the other element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed elements. The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, from another component, region, layer. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.

[0078] Terms such as “inner,” “outer,” "beneath," "below," "lower," "above," "upper," and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.

[0079] To address the issues of conventional dual-fuel engines, the present disclosure envisages a multi -fuel combustion ignition engine. Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.

[0080] The multi-fuel compression ignition engine (100) comprises a port injection system (102) and a direct injection system (104). The port injection system (102) is configured to inject a first fuel in an intake manifold (102A) of the engine (100). The direct injection system (104) is configured to inject a second fuel directly into a combustion chamber (110A) of the engine (100).

[0081] In an embodiment, the port injection system (102) is a multi-point fuel injection (MPFI) system and the direct injection system is a rail direct injection system (CRDI).

[0082] The engine (100) includes at least one cylinder (110). The cylinders (110) are arranged in a straight line configuration or V shape configuration or a flat configuration. Each cylinder (110) encloses a piston (112) that moves up and down for converting fuel into mechanical energy through the combustion process.

[0083] In an embodiment, the engine (100) includes a plurality of cylinders (110) and each cylinder encloses a crown piston (112).

[0084] The cylinder head (not shown in the figure) of the cylinder (110) is configured to house a port injection system (102) and a direct injection system (104). Figure 1 illustrates a sectional view of the cylinder of the multi -fuel compression ignition engine. The first fuel is selected from ethanol or blended ethanol and the second fuel is selected from Iso-octane or blended Iso-octane. The ratio of the first fuel to the second fuel injected in the combustion chamber (110A) is in the range 60:40 to 90: 10.

[0085] The objective of the present disclosure is to provide an engine that uses renewable fuels such as ethanol to the maximum possible extent without compromising performance.

[0086] In a preferred embodiment, the first fuel is only ethanol.

[0087] In another embodiment, blended ethanol includes ethanol in the range of 50% to 60% and fossil fuels in the range of 50% to 60%.

[0088] Blended Iso-octane includes Iso-octane in the range of 30% to 70% and N-heptane in the range of 30% to 70%.

[0089] In an embodiment, blended Iso-octane includes 70% Iso-octane and 30% N-heptane. Exceeding this ratio would impair engine performance, as the cetane number of the fuel mixture would decrease, making it unsuitable for diesel engines.

[0090] In an embodiment, blended Iso-octane includes 30% Iso-octane and 70% N-heptane. Below this ratio, the fuel mixture will have difficulty handling the engine's high compression because of reduced Iso-octane content.

[0091] In an embodiment, blended Iso-octane includes 50% Iso-octane and 50% N-heptane. This ratio is ideal for maximizing engine performance. N-heptane maintains the cetane number, while Iso-octane, with its high octane rating, enables the fuel to withstand high compression.

[0092] In an embodiment, ethanol or blended ethanol has a calorific value in the range of 20 MJ / kg to 30 MJ / kg.

[0093] In an embodiment, Iso-octane has a calorific value in the range of 40 MJ / kg to 50 MJ / kg. The higher calorific values of the fuel improve engine efficiency.

[0094] The first fuel and the second fuel have a high octane number. The high octane number indicates a higher resistance to autoignition of the fuel. Such fuels ensure compatibility, reduced knocking and controlled combustion. Also, Iso-octane fuel or blended Iso-octane produce lower emissions of pollutants. Both fuel injection systems may include a fuel tank, a fuel pump, a fuel filter, a fuel rail, a fuel injector, a fuel pressure regulator and a throttle body. The first fuel and the second fuel are stored in separate fuel tanks.

[0095] The engine (100) includes a plurality of sensing units (114) (not shown) to detect predetermined parameters in the operative configuration of the engine. The sensing unit (114) includes an intake manifold pressure sensor, an air temperature sensor, a throttle position sensor, an oxygen sensor and an in-cylinder pressure sensor.

[0096] The engine (100) includes an engine control unit (ECU) (116) (not shown). The engine control unit (116) is in communication with sensing units (114). The engine control unit (116) receives inputs from the plurality of sensing units (114). Based on the received inputs, the engine control unit generates control signals to control the operation of the port injection system (102) and the direct injection system (104). The port injection system (102) and the direct injection system (104) are in communication with the engine control unit (116) to receive control signals to control the timing and amount of fuel injected in the cylinders (HO).

[0097] The engine control unit (116) includes a repository that stores algorithms.

[0098] In an embodiment, the engine control unit (116) includes a microcontroller, a memory, a power supply circuit, an analog-to-digital converter, a sensor interface, an actuator interface, a communication interface, control algorithms and protection circuitry.

[0099] In an embodiment, the engine control unit (116) is configured to control the operation of the inlet valve (106) and the exhaust valve (108). The engine control unit (116) is configured to precisely control the timing, duration, and lift of intake valves (106) and exhaust valves (108) to optimize engine performance, fuel efficiency, and emissions.

[0100] The engine (100) includes an exhaust after-treatment system (118) (not shown). The exhaust after-treatment system (118) reduces the harmful emissions produced by the multi -fuel combustion engine (100) before these exhaust gases are released into the atmosphere. The system (118) reduces emissions of pollutants such as nitrogen oxides (NOx), particulate matter (PM), hydrocarbons (HC), and carbon monoxide (CO). The system (118) includes a catalytic converter to facilitate the conversion of harmful emissions into less harmful gases. In an embodiment, the exhaust after-treatment system (118) has a microporous carbon filter unit.

[0101] In an embodiment, the exhaust after-treatment system (118) includes a catalytic converter with a sulfur capture layer. The catalytic converter with a sulfur capture layer specifically addresses the issue of sulfur compounds in exhaust gases, such as sulfur dioxide (SO2).

[0102] Further, the engine (100) includes a preheater mechanism (120) (not shown) configured to heat the intake air or air-fuel mixture before the air enters the combustion chamber (110A). The preheating of the fuel mixture ensures easy ignition of the engine and prevention of coldstart problems.

[0103] The preheater mechanism (120) includes a temperature sensor, a preheater, a control unit and a power supply. The temperature sensor is a thermistor or thermocouple capable of accurately detecting engine temperature in real-time. The preheater consists of electric heating elements made from materials such as nichrome wire or PTC (Positive Temperature Coefficient) ceramics, which provide fast and efficient heat transfer. These elements are placed strategically around the engine components that require preheating for optimal ignition, such as the fuel injectors, air intake, and combustion chamber. The control unit is programmed to regulate the preheater based on the real-time temperature data from the sensor. The preheater is powered by the vehicle’s 12V or 24V electrical system. A relay or solid-state switch ensures that the preheater only operates when necessary, avoiding continuous operation that could lead to overheating or battery drain.

[0104] In an embodiment, the preheater mechanism (120) is selected from a coolant preheater, a fuel preheater, an intake air pre-heater, and an oil pre-heater.

[0105] In an embodiment, the compression ratio of the engine (100) is increased by increasing the stroke length of the piston (112) and using domed or crown pistons in the cylinders (110).

[0106] In an embodiment, the engine (100) is equipped with a mild-hybrid technology. The mild- hybrid technology includes an electric motor and a battery. The mild-hybrid technology assists the engine (100) with starting, accelerating and powering other auxiliary systems of the engine (100). Further, the present disclosure envisages a method (200) of operating a multi-fuel compression ignition engine (100). The method includes the following steps: at step 202: injecting a predetermined amount of a first fuel in the intake manifold (102 A) by a port injection system (102); at step 204: feeding a mixture of the first fuel and the air into the combustion chamber (110A) during the suction stroke of the engine (100) through an intake valve (106); at step 206: compressing the mixture of the first fuel and the air in the combustion chamber (110A) with a compression ratio ranging from 14: 1 to 20: 1; at step 208: injecting a second fuel directly into the combustion chamber (110A) near the end of the compression stroke using a direct injection system (104) to initiate compression ignition and a power stroke; and at step 210: expelling the burnt gases from the combustion chamber (110A) during the exhaust stroke.

[0107] In an embodiment, the method (200) includes the following steps: at step 302: sensing the operating parameters of the engine (100) using an intake manifold pressure sensor (114A), an air temperature sensor (114B), a throttle position sensor (114C), an oxygen sensor (114D) and an in-cylinder pressure sensor (114E); at step 304: sending sensed parameters to said engine control unit (116); at step 306: determining the optimum fuel injection time and fuel amount by said engine control unit (116); at step 308: generating a control signal by said engine control unit (116) for controlling the operation of the port injection system (102) and the direct injection system (104).

[0108] In an embodiment, the method (200) includes the step of: preheating the air before the air enters an intake manifold (102A) and a combustion chamber (110A).

[0109] In an embodiment, the method (400) of operating a multi-fuel compression ignition engine (100), includes the following steps: at step 402: sensing the operating parameters of the engine (100) using an intake manifold pressure sensor (114A), an air temperature sensor (114B), a throttle position sensor (114C), an oxygen sensor (114D) and an in-cylinder pressure sensor (114E); at step 404: sending sensed parameters to said engine control unit (116); at step 406: determining the optimum fuel injection time and fuel amount by said engine control unit (116); at step 408: generating a control signal by said engine control unit (116) for controlling the operation of the port injection system (102) and the direct injection system (104);

[0110] - at step 410: injecting a predetermined amount of a first fuel in the intake manifold (102A) by a port injection system (102);

[0111] - at step 412: feeding a mixture of the first fuel and the air into the combustion chamber (110A) during the suction stroke of the engine (100) through an intake valve (106);

[0112] - at step 414: compressing the mixture of the first fuel and the air in the combustion chamber (110A) with a compression ratio ranging from 14: 1 to 20: 1;

[0113] - at step 416: injecting a second fuel directly into the combustion chamber (110A) near the end of the compression stroke using a direct injection system (104) to initiate compression ignition and a power stroke; and

[0114] - at step 418: expelling the burnt gases from the combustion chamber (110A) during the exhaust stroke.

[0115] In an embodiment, the method (400) includes a step of:

[0116] - preheating the air before the air enters an intake manifold (102A) and a combustion chamber (110A). In different driving scenarios, the engine control unit (116) controls the engine operation to generate the torques required for seamless propulsion of the vehicle.

[0117] EXPERIMENT

[0118] In an exemplary embodiment, the multi-fuel compression engine is run on two fuels including the first fuel and the second fuel. Two sets of fuels are separately injected in the engine (100) to measure the emission parameters of the engine (100). In the first set, the fuel is Diesel. In the second set, the first fuel is ethanol or blended ethanol and the second fuel is Iso-octane. In both cases, a port injection system (102) and a direct injection system (104) are used to inject fuels into the combustion chamber (110A). The port injection system (102) is used to inject the first fuel in an intake manifold of the engine (100). A mixture of the first fuel and the air is injected into the combustion chamber (110A) during the suction stroke through an inlet valve. Further, the direct injection system (104) is used to inject the second fuel into the combustion chamber (110A) near the end of the compression stroke. The speed of the engines is maintained at 2500 RPM. The exhaust emissions of the engine (100) are measured using a pollution under control (PUC) machine.

[0119] The smoke density of the emissions produced by the injection of both sets of fuels is measured. It was observed that the smoke density of the emission gas produced while the engine (100) is running on diesel is 0.66. Further, the smoke density of the emission gas produced while the engine (100) runs on ethanol as the first fuel and Iso-octane as the second fuel is 0.27. Lower smoke density indicates controlled combustion and proper air-fuel mixture. Table 1 illustrates the parameters measured during the experimentation with two sets of fuels.

[0120] Table 1

[0121] The multi-fuel compression ignition engine (100) offers performance similar to a diesel engine while operating on renewable fuel such as ethanol. Further, the engine (100) does not require a complex and expensive exhaust after-treatment system as required in the case of the diesel engines. The use of high-octane rating fuel such as Iso-octane improves combustion efficiency while reducing NOx, carbon dioxide (CO2), sulphur oxides (SOx) and particulate matter emissions.

[0122] The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.

[0123] TECHNICAL ADVANCEMENTS

[0124] The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a multi-fuel compression ignition engine, that:

[0125] • facilitates controlled combustion of fuels and reduced engine knocking;

[0126] • lowers emissions of harmful pollutants in the environment;

[0127] • prevents cold-start problems; and

[0128] • has high efficiency.

[0129] The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and / or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

[0130] The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

[0131] Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

[0132] While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Claims

CLAIMS:

1. A multi -fuel compression ignition engine (100), comprising: a port injection system (102) configured to inject a first fuel in an intake manifold (102 A) of said engine (100); and a direct injection system (104) configured to inject a second fuel directly into a combustion chamber (110A) of said engine (100). wherein, said first fuel is selected from ethanol or blended ethanol and said second fuel is selected from Iso-octane or blended Iso-octane.

2. The multi-fuel compression ignition engine (100) as claimed in claim 1, wherein the ratio of the first fuel to the second fuel injected in the combustion chamber (110A) is in the range 60:40 to 90: 10.

3. The multi-fuel compression ignition engine (100) as claimed in claim 1, wherein said blended ethanol includes ethanol in the range of 50% to 60% and fossil fuels in the range of 50% to 60%.

4. The multi-fuel compression ignition engine (100) as claimed in claim 1, wherein said blended Iso-octane includes Iso-octane in the range of 30% to 70% and N-heptane in the range of 30% to 70%.

5. The multi -fuel compression ignition engine (100) as claimed in claim 1, which includes a plurality of cylinders (110), and each cylinder (110) encloses a crown piston (112).

6. The multi-fuel compression ignition engine (100) as claimed in claim 1, which includes a plurality of sensing units (114) to detect predetermined parameters; said sensing units (114) include an intake manifold pressure sensor (114A), an air temperature sensor (114B), a throttle position sensor (114C), an oxygen sensor (114D) and in-cylinder pressure sensor (114E).

7. The multi-fuel compression ignition engine (100) as claimed in claim 6, which includes an engine control unit (ECU) (116) configured to receive inputs from saidplurality of sensing units (114), and generate control signals based on the received inputs to control the operation of the port injection system (102) and the direct injection system (104).

8. The multi-fuel compression ignition engine (100) as claimed in claim 7, wherein said port injection system (102) and said direct injection system (104) are in communication with said engine control unit (116) to receive control signals to control the timing and the amount of fuel injected in the cylinders (110).

9. The multi-fuel compression ignition engine (100) as claimed in claim 1, which includes an exhaust after-treatment system (118) having a microporous carbon filter unit.

10. The multi -fuel compression ignition engine (100) as claimed in claim 1, which includes a preheater mechanism (120) configured to heat the intake air or air-fuel mixture before the air enters said combustion chamber (110A).

11. A method (200) of operating a multi-fuel compression ignition engine (100) which includes the following steps:- injecting a predetermined amount of a first fuel in said intake manifold (102A) by a port injection system (102);- feeding a mixture of said first fuel and the air into said combustion chamber (110A) during the suction stroke of said engine (100) through an intake valve (106);- compressing the mixture of said first fuel and the air in the combustion chamber (110A) with a compression ratio ranging from 14: 1 to 20: 1;- injecting a second fuel directly into said combustion chamber (110A) near the end of the compression stroke using a direct injection system (104) to initiate compression ignition and a power stroke; and- expelling the burnt gases from the combustion chamber (110A) during the exhaust stroke.

12. The method (200) as claimed in claim 11, which includes the step of:preheating the air before the air enters an intake manifold (102A) and a combustion chamber (110A).

13. The method (200) as claimed in claim 11, which includes the steps of: sensing operating parameters of the engine (100) using an intake manifold pressure sensor (114A), an air temperature sensor (114B), a throttle position sensor (114C), an oxygen sensor (114D) and an in-cylinder pressure sensor (114E); sending sensed parameters to said engine control unit (116);- determining optimum fuel injection time and the fuel amount by said engine control unit (116); and- generating control signal by said engine control unit (116) to control the operation of the port injection system (102) and the direct injection system (104).

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