WO2008116667A1

WO2008116667A1 - An engine system

Info

Publication number: WO2008116667A1
Application number: PCT/EP2008/002516
Authority: WO
Inventors: John Butler
Original assignee: John Butler
Priority date: 2007-03-28
Filing date: 2008-03-28
Publication date: 2008-10-02

Abstract

The present invention discloses an engine system, that houses a fluid compound, comprising a refrigeration element to receive a fluid compound, refrigerate the fluid compound and output liquid fluid compound; a pump, in fluid communication with the refrigeration element, to receive the liquid fluid compound and pressurise the liquid fluid compound; a heat exchanger, in fluid communication with the pump, to receive the pressurised liquid fluid compound and to enable exchange of heat between fluid compound flowing within the engine system and the pressurised liquid fluid compound to form gaseous fluid compound therefrom; a heat source, in fluid communication with the heat exchanger, to receive the gaseous fluid compound and to heat the gaseous fluid compound to form expanding gaseous fluid compound, and a work mechanism, in fluid communication with the heat source, to receive the expanding gaseous fluid compound and to use the expanding gaseous fluid compound to effect mechanical work.

Description

Title: An Engine System

Field of the invention:

The invention relates to an engine system and in particular to an engine system that converts heat energy to mechanical energy with improved efficiency.

Background to the invention:

Existing engine systems, including four stroke engines, operate to convert heat energy to mechanical energy. The four strokes, or phases, refer to intake, compression, combustion and exhaust phases. In the intake phase, air and fuel are input into a cylinder of the engine. During the compression phase, the air and fuel within the engine cylinder are compressed. The fuel and air mixture are then combusted during the combustion phase. During combustion the air within the engine is heated by the combustion and expands. The expanding air is used to mechanically operate a piston of the engine, which may, in turn, cause rotation of a crank shaft attached to the piston. The efficiency of such an engine is determined by how much of the heat energy, generated through combustion of the fuel, is converted to mechanical energy

(moving the piston and/or rotating the crank shaft). In a diesel engine it is estimated that less then 50% of the heat energy generated is converted to mechanical energy, the remaining heat energy is lost through an exhaust outlet during the exhaust phase or is dissipated through the walls of the engine.

In one cycle of such an engine, the piston completes four movements or strokes. The acceleration of the piston in each stroke generates a large amount of vibration in the engine. During the compression phase of the four stroke engine, large amounts of work must be done by the piston, in order to compress the air and fuel within the engine cylinder. The expenditure of work, to effect the compression, decreases the overall efficiency of the engine.

The expanding heated air that is formed during the combustion phase, is used to do work. Work is done during the combustion phase only, therefore, in a combustion engine, work can only be done intermittently. As described above, in a four stroke engine the work is done to operate a piston. In turbine systems an expanding heated gas is directed to flow over a turbine. The flow of the expanding heated gas causes the turbine to rotate, thereby generating mechanical energy. In many cases the gas is often so hot that is causes damage to the turbines, such as burning of the turbine blades.

Other engine systems, such as the gas engine, tend to be noisy during operation. The efficiency of gas engines is also low, and is of the order of 30%. Furthermore, start-up of such engines requires a large amount of power.

The inefficiency of existing engine systems means that a larger amount of fuel must be burned to obtain a given mechanical energy. Burning large amounts of fuel will result in an increase in emissions, e.g. in jet or gas engines large amounts of carbon dioxide are produced.

Existing engines, such as the diesel engine, require a battery for startup. The battery increases the weight, cost of manufacture and the cost of running the engine. Summary of the invention:

According to a first aspect of the invention there is provided an engine system, that houses a fluid compound, comprising a refrigeration element to receive fluid compound, refrigerate the fluid compound and output liquid fluid compound; a pump, in fluid communication with the refrigeration element, to receive the liquid fluid compound and pressurise the liquid fluid compound; a heat exchanger, in fluid communication with the pump, to receive the pressurised liquid fluid compound and to exchange heat between fluid compound flowing within the engine system and the pressurised liquid fluid compound to form gaseous fluid compound therefrom; a heat source, in fluid communication with the heat exchanger, to receive the gaseous fluid compound and to heat the gaseous fluid compound to form expanding gaseous fluid compound; and a work mechanism, in fluid communication with the heat source, to receive the expanding gaseous fluid compound and to use the expanding gaseous fluid compound to effect mechanical work.

The fluid compound received by the refrigeration element may be gaseous fluid compound. The fluid compound received by the refrigeration element may be liquid fluid compound. The fluid compound received by the refrigeration element may be a combination of gaseous fluid compound and liquid fluid compound.

Mechanically compressing gaseous fluid compound (for example as is done in the four stroke engine) requires a large amount of work. Unlike the compressor of the four stroke engine, which mechanically compresses the gaseous fluid compound to increase the pressure of the gas molecules, when the refrigeration element receives at least part gaseous fluid compound, the refrigeration element achieves compression of the molecules of the gaseous fluid compound by effecting a phase change (i.e. a change from a gas to a liquid) of the fluid compound. The work required to effect a phase change is much less then the work required to mechanically compress the gaseous fluid compound. Therefore, the refrigeration element can implement the effects of mechanical compression without the large expenditure of work, thereby providing an engine system with improved efficiency.

In addition to the above, because the fluid compound received by the pump is in liquid phase, the fluid compound may be raised to high pressure with minimum mechanical effort by the pump.

The engine system of the invention is also capable of operating at high pressure and at a relatively low temperature.

The heat exchanger of the engine system may be a counter-flow heat exchanger. The use of a counter-flow heat exchanger increases the thermal efficiency of the heat exchanger and maximizes the heat exchange between the fluid compound flowing within the heat exchanger. Maximizing heat exchange improves the overall efficiency of the engine system.

The heat exchanger may comprise a tapered flow channel. The direction of the taper in the flow channel can be chosen so that the pressure of the fluid compound is either increased or decreased as it flows through the heat exchanger. Such an arrangement can be used to cool or heat the fluid compound flowing in the heat exchanger. The heat source may be at least one of a counter-flow heat exchanger, a burner or an electrical heater. Alternative heat sources include heat sources using internal combustion. The heat source may be located external to a flow channel of the engine system which connects the heat exchanger and the work mechanism, to provide heat to fluid compound flowing through the flow channel. Alternatively, the heat source may be located within the flow channel.

The engine system may further comprise a pressurised storage cylinder that stores the fluid compound which has been pressurised by the pump. The storage cylinder may comprise a release valve, which may be positioned in a first, open, position in which the fluid compound can flow from the storage cylinder to the heat exchanger, or in a second, closed, position in which the fluid compound is prevented from flowing from the storage cylinder. The facility to store the fluid compound in a pressurised environment, removes the need for a battery to initiate the start-up of the engine system. The start-up of the engine system may be effected simply by opening the release valve, which will allow the pressurised fluid compound stored in the storage cylinder, to flow within the engine system.

The fluid compound may be at least one of a nitrogen, oxygen, oxide of nitrogen, compounds of nitrogen and hydrogen, hydrogen, helium, an oxide of carbon, hydrocarbon, an oxide of sulphur, halogenated hydrocarbon, oxygenated hydrocarbons or a noble gas. Preferably, the fluid compound is carbon dioxide. The use of such fluid compounds reduces the amount of heat energy dissipated to effect phase change, as these compounds all possess a low latent heat of vapourisation and a low latent heat of condensation. Consequently, these fluid compounds are gaseous at ambient temperature. A low latent heat of vapourisation reduces the work required in the heat exchanger to vapourise the liquid fluid compound, while the low latent heat of condensation reduces the work required in the refrigerator to condense received gaseous fluid compound. Such fluid compounds therefore increase the total amount of heat energy that is available to be converted to work, thereby increasing the overall efficiency of the engine system.

In improving the efficiency of the engine system, less fuel is required in order to achieve a given mechanical energy. The reduction in the amount of fuel used, means a decrease in emissions generated by the engine system.

The volume of emissions may be reduced to a level in which they can be stored in a compartment and later disposed of.

The engine system may further comprise an emission storage compartment, to store emissions generated by the engine system. Storing the engine emissions allows a person to control when the engine emissions are released into the atmosphere. The storage compartment will allow the emissions to be collected and later dumped at a designated dumping area.

The work mechanism may comprise one or more turbine mechanisms. The work mechanism may comprise one or more piston mechanisms. When the work mechanism comprises more than one turbine mechanism, the turbine mechanisms may be arranged in parallel or series. When the work mechanism comprises more then one piston mechanism, the piston mechanisms may be arranged in parallel or series.

The work mechanism may be insulated to reduce noise pollution.

The engine system may further comprise one or more modulating valves. One or more modulating valves may be used to allow expanding gaseous fluid compound which is above a threshold pressure to pass to the work mechanism.

According to a second aspect of the invention there is provided a method of producing mechanical work in a work mechanism of an engine system comprising the steps of; refrigerating a fluid compound to produce a liquid fluid compound; pumping the liquid fluid compound to produce pressurised liquid fluid compound; effecting a phase change of the pressurised liquid fluid compound to produce gaseous fluid compound; heating the gaseous fluid compound to form expanding gaseous fluid compound, and using the expanding gaseous fluid compound to effect mechanical work in the work mechanism.

Brief description of drawings:

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of an engine system of the present invention, and

Figure 2 is a perspective view of a counter-flow heat exchanger used in the engine system of Figure 1.

Detailed description of drawings:

Figure 1 provides a schematic representation of an engine system 1 of the present invention. The engine system 1 comprises a refrigerator 2, a pump 3 in fluid communication with the refrigerator 2, a storage cylinder 4 in fluid communication with the pump 3, a heat exchanger 5 in fluid communication with the storage cylinder 4, a heat source 6 in fluid communication with the heat exchanger 5, and a work mechanism 7, in the form of a series of turbines 7a-7e, each of which is in fluid communication with the heat source 6.

The elements of the engine system 1 are arranged to form a closed system. A fluid compound 8 is contained in and may flow within the closed engine system 1 , through a flow channel 13 connecting each of the elements of the engine system 1. The fluid compound 8, used in the engine system of Figure 1 , is CO₂, however, any suitable fluid may be used, such as an nitrogen, oxygen, oxide of nitrogen, compounds of nitrogen and hydrogen e.g. ammonia, hydrogen, helium, an oxide of carbon, hydrocarbon, an oxide of sulphur, halogenated hydrocarbon, oxygenated hydrocarbons or a noble gas.

The storage cylinder 4 is provided with a valve 12. The valve 12 is movable between a first, open, position in which the fluid compound 8 can flow from the storage cylinder 4 to the heat exchanger 5, and a second, closed, position in which the fluid compound 8 is prevented from flowing from the storage cylinder 4. The position of valve 12 determines the flow of the fluid compound 8 within the engine system 1.

Figure 2 provides a perspective view of the heat exchanger 5 of Figure 1. The heat exchanger 5 is arranged as a counter-flow heat exchanger. The heat exchanger 5 comprises a first channel 9 and a second channel 10. The first channel 9 is arranged to surround the second channel 10. Fluid compound 8 flows in both channels 9,10. However, the fluid compound 8 in each channel flows in opposite directions, as indicated by the arrows shown in Figure 2. The fluid compound 8 flowing in each of the channels will have different temperatures, and heat is transferred from the fluid compound 8 flowing in one of the channels to the fluid compound 8 flowing in the other channel. The fluid compound 8 flowing from the work mechanism 7 flows through channel 9, and the fluid compound 8 flowing from the storage cylinder 4 flows through channel 10. As will be explained later, heat will be transferred from the warm fluid compound 8 flowing in channel 9, to the cooler fluid compound 8 flowing in channel 10.

The heat source 6 may comprise any suitable heating mechanism, arrangeable to heat the fluid compound 8 flowing within the engine system 1. The heat source 6 of Figure 1 is a burner 6. The burner 6 is located externally of the flow channel 13. The burner 6 heats the fluid compound 8 flowing in the flow channel 13, by means of conduction.

The engine system 1 acts to generate heat energy, by the operation of the refrigerator 2, the pump 3, the heat exchanger 5 and the heat source 6, and uses the heat energy to produce expansion of the fluid compound which in turn effects mechanical work in the work mechanism.

Returning to Figure 1 , during an operation cycle of the engine system 1 , the refrigerator 2 receives fluid compound 8 from the heat exchanger 5, refrigerates this and outputs liquid fluid compound 8. The fluid compound received by the refrigeration element may be gaseous fluid compound, liquid fluid compound, or a combination of gaseous fluid compound and liquid fluid compound. When at least part of the received fluid compound comprises gaseous fluid compound, refrigeration of the gaseous fluid compound cools the gaseous fluid compound, removing the kinetic energy that the molecules of the gaseous fluid compound possess, thereby condensing the gaseous fluid compound to form a liquid fluid compound. Once condensed, the molecules of the liquid fluid compound 8 will be in a highly compressed form, as the kinetic energy of the molecules will have been greatly reduced by the change of phase from gas to liquid. When at least part of the received fluid compound comprises liquid fluid compound, the refrigerator 2 acts to cool the liquid fluid compound. In each case, the refrigerator 2 outputs liquid fluid compound.

The liquid fluid compound is output from the refrigerator 2 to the pump 3. The pump 3 is used to increase the pressure of the liquid fluid compound 8. The pump 3 raises the pressure of the liquid fluid compound to an operating pressure and also, when the valve 12 is open, directs the flow of the liquid fluid compound 8 in a desired direction within the engine system. The liquid fluid compound 8 is output from the pump 3 to the storage cylinder 4, where it is stored. The liquid fluid compound 8 is stored under pressure within the storage chamber 4.

On opening valve 12, the liquid fluid compound 8 flows from the storage cylinder 4 to the heat exchanger 5. The liquid fluid compound 8 flows into the second channel 10 of the heat exchanger 5. Gaseous fluid compound 8 is flowing in the opposite direction through the first channel 9 of the heat exchanger 5. The gaseous fluid compound is warmer than the liquid fluid compound. The liquid fluid compound 8 flowing in the second channel 10 receives heat energy from the warmer gaseous fluid compound 8 flowing through the first channel 9. An amount of heat energy which is at least equal to the latent heat of vapourisation of the liquid fluid compound, is exchanged between the warmer gaseous fluid compound 8 flowing through the first channel 9 and the cooler liquid fluid compound flowing the second channel 10. Thus a phase change is effected in the liquid fluid compound flowing in the second channel 10 to convert this to gaseous fluid compound.

The gaseous fluid compound 8 is directed to the heat source 6. The heat source 6 adds heat energy to the gaseous fluid compound, which causes the gaseous fluid compound to expand. The expansion of the gaseous fluid compound will cause the gaseous fluid compound to flow from the heat source 6 to the work mechanism 7.

The gaseous fluid compound 8 is channeled to flow over the turbines 7a-7e of the work mechanism. This flow is used to drive the turbines 7a-7e. The turbines 7a-7e are arranged in series, and each successive turbine in the series receives gaseous fluid compound of progressively decreasing pressure, as at each turbine an amount of gaseous fluid compound will be expended in driving that turbine. In driving the turbines 7a-7e, the gaseous fluid compound effects mechanical movement i.e. mechanical work of the turbines.

After the gaseous fluid compound 8 has flowed over the final turbine 7e, the gaseous fluid compound will no longer possess sufficient pressure to drive another turbine. However, the gaseous fluid compound will still be in the form of a warm gaseous fluid compound.

The warm gaseous fluid compound 8, coming from the series of turbines 7a-7e, is passed to the heat exchanger 5 and is directed to flow through the first channel 9. The heat energy remaining in the warm gaseous fluid compound, is transferred to the much cooler liquid fluid compound 8 flowing in the opposite direction in the second channel 10 of the heat exchanger 5. The amount of heat energy transferred from the gaseous fluid compound 8 flowing in the first channel 9 of the heat exchanger 5, to the liquid fluid compound 8 flowing in the channel 10 of the heat exchanger 5, will be approximately be equal to the latent heat of condensation of the gaseous fluid compound 8. Depending on the amount of heat exchange that has occurred, the fluid compound 8 flowing in channel 9, that is output from the heat exchanger 5 may be in the form or a liquid, gas or a combination thereof.

The fluid compound output from the heat exchanger 5 is returned to the refrigerator 2, where the operation cycle of the engine system 1 repeats. The amount of energy required by the refrigerator 2 to refrigerate the fluid compound 8 is reduced as, an amount of heat has already been removed through the heat exchange that occurred in the heat exchanger 5.

Optionally, the heat generated by the refrigerator 2 in refrigerating the fluid compound, can be used to heat the liquid fluid compound flowing in the second channel 10 of the heat exchanger 5. The addition of such heat will reduce the amount of heat energy required by the heat source 6 to expand the gaseous fluid compound 8.

Claims

1. An engine system, that houses a fluid compound, comprising a refrigeration element to receive fluid compound, refrigerate the fluid compound and output liquid fluid compound; a pump, in fluid communication with the refrigeration element, to receive the liquid fluid compound and pressurise the liquid fluid compound; a heat exchanger, in fluid communication with the pump, to receive the pressurised liquid fluid compound and to exchange heat between fluid compound flowing within the engine system and the pressurised liquid fluid compound to form gaseous fluid compound therefrom; a heat source, in fluid communication with the heat exchanger, to receive the gaseous fluid compound and to heat the gaseous fluid compound to form expanding gaseous fluid compound; and a work mechanism, in fluid communication with the heat source, to receive the expanding gaseous fluid compound and to use the expanding gaseous fluid compound to effect mechanical work.

2. The engine system according to Claim 1 , wherein the heat exchanger of the engine system is a counter-flow heat exchanger.

3. The engine system according to any preceding claim, wherein the heat exchanger further comprises at least one tapered flow channel.

4 The engine system according to any preceding claim, wherein the heat source is at least one of a counter-flow heat exchanger, a burner or an electrical heater.

5. The engine system according to any preceding claim, wherein the engine system further comprises a pressurised storage cylinder that stores the fluid compound which has been pressurised by the pump.

6. The engine system according to Claim 5, wherein the storage cylinder comprises a release valve, which may be positioned in a first, open, position, in which the fluid compound can flow from the storage cylinder to the heat exchanger, or in a second, closed, position in which the fluid compound is prevented from flowing from the storage cylinder.

7. The engine system according to any preceding claim, wherein the fluid compound is at least one of a nitrogen, oxygen, oxide of nitrogen, compounds of nitrogen and hydrogen, hydrogen, helium, an oxide of carbon, hydrocarbon, an oxide of sulphur, halogenated hydrocarbon, oxygenated hydrocarbons or a noble gas.

8. The engine system according to any preceding claim, wherein the fluid compound is carbon dioxide.

9. The engine system according to any preceding claim, wherein the engine system further comprises an emission storage compartment, to store emissions generated by the engine system.

10. The engine system according to any preceding claim, wherein the work mechanism comprises one or more turbine mechanisms.

11. The engine system according to any preceding claim, wherein the work mechanism comprises one or more piston mechanisms.

12. The engine system according to Claim 10, wherein the work mechanism comprises more than one turbine mechanism and the turbine mechanisms are arranged in parallel.

13. The engine system according to Claim 10, wherein the work mechanism comprises more than one turbine mechanism and the turbine mechanisms are arranged in series.

14. The engine system according to Claim 11 , wherein the work mechanism comprises more than one piston mechanism, and the piston mechanisms are arranged in parallel.

15. The engine system according to Claim 11 , wherein the work mechanism comprises more than one piston mechanism, and the piston mechanisms are arranged in series.

16. The engine system according to any preceding claim, wherein the work mechanism is insulated to reduce noise pollution.

17. The engine system according to any preceding claim, wherein the engine system further comprises one or more modulating valves which allow expanding gaseous fluid compound which is above a threshold oressure to oass to the work mechanism.

18. A method of producing mechanical work in a work mechanism of an engine system comprising the steps of; refrigerating a fluid compound to produce a liquid fluid compound; pumping the liquid fluid compound to produce pressurised liquid fluid compound; effecting a phase change of the pressurised liquid fluid compound to produce gaseous fluid compound; heating the gaseous fluid compound to form expanding gaseous fluid compound; using the expanding gaseous fluid compound to effect mechanical work in the work mechanism.