IT202200026538A1 - IMPROVED ENGINE SYSTEM - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

?IMPROVED ENGINE SYSTEM?

TECHNICAL SECTOR

The present invention relates to an engine system, in particular a vehicle engine or power generation system of the internal combustion type.

The present invention finds a preferred, though not exclusive, application in a splitcycle engine. Reference will be made to this application below by way of example.

STATE OF THE ART NOTE

The split-cycle engine, the so-called ?split-cycle?, has returned to being of particular interest, thanks to its high efficiency which is greater than that of ?classic? internal combustion engines, such as four-stroke engines; this greater efficiency reduces vehicle consumption and consequently polluting emissions.

As is known, the split-cycle engine separates the compression of the air and the combustion of the fuel mixture into two different cylinders.

In fact, while compression requires the lowest possible temperature or the greatest dissipation of the thermal energy developed by compression, combustion instead requires the highest possible temperature or the least dissipation of the thermal energy developed by combustion.

By separating compression from combustion, the split-cycle engine achieves greater efficiency than traditional internal combustion engines.

However, it is known that the air that is compressed to be injected into the combustion chamber has a high percentage of nitrogen equal to about 80%. Nitrogen, being an inert gas, does not participate in combustion and therefore results as an additional load to the compressor that does not bring benefits in combustion.

There is therefore a need to increase the combustion efficiency of engine systems, particularly of the split-cycle type, by reducing the work required by the compressor to compress the air supplied to the combustion chamber.

The aim of the present invention is to satisfy the above mentioned needs in an optimized and economical way.

SUMMARY OF THE INVENTION

The above object is achieved by an engine system as claimed in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, a preferred embodiment is described below, by way of a non-limiting example and with reference to the attached drawing, figure 1, which schematically illustrates an engine system according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

In figure 1, a schematic illustration of the engine system 1 is shown, advantageously of the split-cycle type.

The engine system 1 essentially comprises a combustion module 2 comprising a plurality of cylinders 2?, 2??, 2??? defining respective combustion chambers and configured to receive an inlet air flow Fi and generate combustion as known in the art.

Again as known for the split-cycle technology, the engine system 1 advantageously comprises compression means 3, such as a compressor, suitable for pressurising the inlet air flow Fi to a predefined pressure, preferably greater than 70 bar.

The engine system 1 further comprises air supply means 4 configured to provide a supply air flow Fa to the compression means 3.

In particular, the air supply means 4 may comprise suction means 5 comprising an inlet mouth 5? suitable for sucking air from the external environment and sending it to the compression means 3.

The engine system 1 may also be equipped with energy recovery means 6 configured to recover the thermal energy of the burnt gases exiting the combustion chamber 2.

In particular, the energy recovery means 6 comprises a heat exchanger 7 fluidically interposed between the air supply means 4 and the compression means 3 and configured to heat the air sucked in by the air supply means 4 and directed towards the compression means 3, for example to bring it to a temperature of 450 - 800 °C.

In particular, the energy recovery means 6 may also comprise fluid expansion means 8, such as a turbine, fluidically positioned downstream of the heat exchanger 7 and configured to expand the exhaust gas flow to recover further heat.

The energy recovery means 6 may advantageously finally comprise a water recuperator 9 placed further downstream of the fluid expansion means 8 and configured to recover water from the flow of burnt gases at the end of their expansion.

According to one aspect of the invention, the engine system 1 comprises an oxy-separation module 10 fluidically interposed between the suction means 4, more preferably downstream of the heat exchanger 7, and the compression means 3. The oxy-separation module 10 is configured to reduce the percentage of inert gas present in the supply air flow Fa by means of an oxy-separation reaction favored by the high temperature. In other words, the percentage of oxygen in the supply air flow Fa is increased.

An example of such an oxy-separation module 10 is illustrated in patent application WO2020193833 A1.

By way of example and functionally to the present invention, the general structure and fluid passages inside the oxy-separation module 10 are illustrated in detail in figure 1.

The oxy-separation module 10 is divided into two portions separated by a catalytic membrane configured to allow the execution of chemical reactions aimed at transporting gaseous oxygen from the supply air flow Fa to the inlet air flow Fi.

To this end, the oxy-separation module 10 receives water, W, as input, for example recovered via the water recuperator 9 and allows the escape of a waste air flow Fo, at least partially deoxygenated.

According to a further aspect of the invention, the engine system 1 comprises first water injection means 11 configured to inject water into the compression means 3 according to a predetermined quantity.

Furthermore, the engine system 1 comprises second water injection means 12 configured to inject water into the cylinders 2?, 2??, 2??? in a predetermined quantity.

The operation of the embodiment of the engine system according to the invention described above is as follows.

The intake system 4 draws a flow of supply air Fa towards the compression means 3. During transport towards the latter it is heated by the heat exchanger 7 through which the burnt gases pass towards the turbine 8 and the water recuperator 9. Before passing to the compression means 3, the overheated inlet air flow Fa passes into the oxy-separation module where the percentage of oxygen is enriched by reducing that of inert gases such as nitrogen. In this way, the mass of the supply air flow Fa is reduced and is more easily compressed by the compression means 3 and sent to the cylinders 2?, 2??, 2??? i.e. to the combustion chamber 2. During compression and possibly during and after combustion a predetermined quantity of water is injected by the first and second injector means 11, 12.

From the above, the advantages of an engine system according to the invention are evident.

Thanks to the oxy-combustion module it is possible to decrease the quantity of mass compressed by the compressors, reducing the work required and therefore increasing the general efficiency of the engine system and allowing the gas to be injected into the combustion chamber at high pressures, improving filling and allowing higher PMEs to be achieved.

Preheating the aspirated air flow also allows for an increase in the efficiency of the oxy-separation module, thus increasing the chemical reactions required for oxygen extraction.

The injection of water into the compression means and into the cylinders allows the combustion speed of the hydrogen/oxygen mixture to be modulated, which would otherwise be extremely fast.

The vaporization of water also allows to increase the mass of the working fluid in the cylinder destined to expand and thus widen the area of the cycle and therefore the power generated.

Finally, it is clear that modifications and variations may be made to the engine system according to the present invention which, however, do not go beyond the scope of protection defined by the claims.

For example, the number of cylinders can vary, as can the type of intake system 4, recovery system 7, injector means 11, 12 and compression means 3.

Claims (8)

1.- Internal combustion engine system (1) comprising a combustion chamber (2), compression means (3) and air supply means (4) fluidically connected to said combustion chamber (2), said air supply means (4) being configured to draw in a flow of supply air (Fa) from the external environment to supply it to said compression means (3) configured to increase its pressure to supply an inlet air flow (Fi) to said combustion chamber (2), said engine system (1) comprising an oxy-separation module (10) fluidically interposed between said air supply means (4) and said compression means (3) and configured to reduce the quantity of inert gases present in said flow of supply air (Fa). 2.- Engine system according to claim 1, comprising an energy recovery system (6) fluidically interposed between said air supply means (4) and said oxy-separation module (3), said energy recovery system (6) being configured to increase the temperature of said supply air flow (Fa). 3.- Engine system according to claim 2, wherein said energy recovery system (6) comprises a heat exchanger (7) configured to exchange heat between a flow of burnt gases coming from said combustion chamber (2) and said flow of supply air (Fa). 4.- Engine system according to claim 3, wherein said energy recovery system (6) comprises fluid expansion means (8) fluidically connected downstream of said heat exchanger (7) and a water recuperator (9) fluidically connected downstream of said fluid expansion means (8). 5.- Engine system according to claim 4, wherein said fluid expansion means (8) comprise a turbine. 6.- Engine system according to one of the previous claims, wherein said oxy-separation module (10) receives said flow of supply air (Fa) and water (W) as input and comprises a catalytic membrane configured to allow the passage/generation of oxygen which passes through said catalytic membrane providing said flow of input air (Fi). 7.- Engine system according to one of the previous claims, comprising first water injection means (11) configured to inject water in a predetermined quantity into said compression means (3). 8.- Engine system according to one of the preceding claims, wherein said combustion chamber (2) comprises a plurality of cylinders (2?, 2??, 2???) and wherein said engine system (1) comprises second water injection means (12) configured to inject water in a predetermined quantity into said cylinders (2?, 2??, 2???).