GB2465830A

GB2465830A - External combustion engine

Info

Publication number: GB2465830A
Application number: GB0822117A
Authority: GB
Inventors: Peter Mckay
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-12-04
Filing date: 2008-12-04
Publication date: 2010-06-09
Also published as: GB0822117D0

Abstract

An external combustion engine in the form of a closed-cycle reciprocating piston engine capable of operating on a wide range of fuels and heat sources including concentrated solar, the working fluid is heated in a micro-flash boiler (10) said boiler is an integral part of the cylinder head, that is heated by burners (11), the working fluid is forced into said boiler, when the piston reaches top dead centre, the working fluid is rapidly heated forcing the piston back down the cylinder as the piston reaches bottom dead centre, ports in the cylinder wall connecting the cylinder to the condensing chamber are exposed, as the piston passes bottom dead centre an injection system sprays atomised working fluid from a reservoir into the cylinder, creating a substantial partial vacuum, at top dead centre the working fluid is forced into the micro-flash boiler(10) completing the cycle.

Description

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EXTERNAL COMBUSTION ENGINE

This invention relates to an external combustion engine in the form of a closed-cycle heat engine capable of operating on a wide range of fuels and heat sources including concentrated solar.

External combustion engines in the form of steam engines have been used since the 1700's Thomas Newcomen's atmospheric steam engine, and the more efficient James Watt engine, Robert Stirling showed that a very efficient heat engine could be built using air as a working fluid in a closed-cycle, these early engines lead the way to modem external combustion engines.

According to one embodiment of the present invention there is provided an external combustion engine in the form of a closed-cycle reciprocating piston engine that uses water or other liquids as a working fluid, said fluid is heated in a micro-flash boiler said boiler is an integral part of the cylinder head, is heated by burners acting on the outer wall of said boiler, the inner wall of said boiler has a relatively large surface area achieved by undulations, nodes, fins, or other shapes, the working fluid is forced into said boiler via apertures on the inner wall of the cylinder head, when the piston reaches top dead centre, the working fluid is rapidly heated close to critical temperature, as the piston is forced back down the cylinder increasing the volume in the cylinder the working fluid is flashed off, at relatively close to bottom dead centre all the working fluid in the boiler has flashed off to vapour, as the piston reaches bottom dead centre ports in the cylinder wall connecting the cylinder to the condensing chamber are exposed, allowing the higher pressure of the cylinder to pass into said condensing chamber, blowing any condense and residual working fluid off the top of the piston into the condensing chamber, said condensing chamber is in the form of a reservoir and heat exchanger for cooling the working fluid close to ambient atmospheric temperature, as the piston passes bottom dead centre the condenser ports are covered, at this point in the cycle a mechanical or electronic injection system sprays an atomise measure of working fluid from the reservoir into the cylinder, this causes the remaining vapour to condense out creating a substantial partial vacuum this is acted on by atmospheric pressure and any crankcase pressure, the working fluid recovers some of the latent heat from the condensing phase change, said working fluid is further preheated as the dome headed piston accelerates up the cylinder bringing said working fluid into contact with the inner wall of the cylinder, the outer wall of said cylinder is heated by exhaust gas from the burners, at top dead centre the preheated working fluid is forced into the micro-flash boiler completing the cycle.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which:-Fig 1 shows a part cross-sectional side view of the engine with the piston at top dead centre pushing the working fluid into the micro-flash boiler.

Fig 2 shows a part cross-sectional side view of the engine with the piston on the power stroke.

Fig 3 shows a part cross-sectional side view of the engine at the condensing phase with the piston at bottom dead centre.

Fig 4 shows a part cross-sectional side view of the working fluid being injected into the engine cylinder.

FigS shows a part cross-sectional side view of the engine illustrating the working fluid being preheated on the cylinder inner wall.

Fig 6 shows a part cross-sectional side and top view of the upper cylinder and heat exchanger.

Referring to the drawing one embodiment of the present invention is a external combustion engine in the form of a reciprocating piston engine that uses water as a working fluid said fluid is heated by burning fuel LPG heating a micro-flash boiler 10 said boiler is an integral part of the cylinder head 11 and is heated by burners 12 acting on the outer wall of said boiler 10, the inner wall of said boiler 10 has a relatively large surface area achieved by undulations, nodes, fins, or other shapes, the cylinder head wall 23 at the point where the boiler 10 is connected should be as narrow a gauge as structural integrity will allow to reduce heat loss by conduction to said cylinder head wall 23 further reduction of heat loss from said cylinder head wall 23 and boiler 10 is achieved by a cap of low density ceramic insulation 11, there is also provided a heat exchanger using heat from the combustion chamber 26 to heat the outer wall of the cylinder 13 and the incoming air 14 for the burners 12 (igniters not shown) before exiting the flue 25 fig.6, when the piston 20 reaches top dead centre, the working fluid is forced into said boiler 10 via apertures 31 on the inner wall of the cylinder head 23 rapidly heating said working fluid close to critical temperature (fig. 1) as the piston 20 is forced back down the cylinder 24 the volume in the cylinder increases the working fluid is flashed off (fig.2), at relatively close to bottom dead centre all the working fluid in the boiler 10 has flashed off to vapour, as the piston 20 reaches bottom dead centre ports 19 in the cylinder wall connecting the cylinder to the condensing chamber 27 are exposed allowing some of the high pressure working fluid in the cylinder to pass into said condensing chamber 27 (fig.3), blowing any condense and residual working fluid off the top of the piston 20 into the condensing chamber 27, said condensing chamber 27 is in the form of a reservoir 16 and heat exchanger 15 for cooling the working fluid close to ambient atmospheric temperature, there is also provided an expansion piston 18 giving extra volume when the condensing ports 19 are open, it is appreciated a relatively larger fixed condensing chamber could be used, when the piston 20 passes bottom dead centre the condenser ports 19 are covered, by the piston rings 30, at this point in the cycle a (mechanical not shown) or electronic injection system 17 sprays an atomise measure of working fluid from jets 29 into the cylinder (fig.4), from the base of the reservoir 16, this causes the remaining vapour to condense out creating a substantial partial vacuum this is acted on by atmospheric pressure and any crankcase pressure, the working fluid recovers some of the latent heat from the condensing phase change, said working fluid is further preheated as the dome headed piston 20 accelerates up the cylinder 24 bringing said working fluid into contact with the inner wall of the cylinder 24 (fig.5), the outer wall 13 of said cylinder is heated by exhaust gas from the burners 12, at top dead centre the preheated working fluid is forced into the micro-flash boiler 10 completing the cycle, at top dead centre the crankcase 28 and condensing chamber 27 will be at ambient atmospheric pressure any loss of crankcase pressure through seals etc. is replaced via non-return valve 22, the difference in pressure between the crankcase 28 and the condensing chamber 27 on the power stroke is used to pump any condensed working fluid that may of accumulated in said crankcase 28 via drain tube 21, this embodiment of the invention uses sealed for life type bearings, other lubricating systems could be provided (not shown).

Claims

CLAIMS1 An external combustion engine in the form of a closed-cycle reciprocating piston engine that uses water or other liquids as a working fluid, said fluid is heated in a micro-flash boiler said boiler is an integral part of the cylinder head, is heated by burners acting on the outer wall of said boiler, the inner wall of said boiler has a relatively large surface area achieved by undulations, nodes, fins, or other shapes, the working fluid is forced into said boiler via apertures on the inner wall of the cylinder head, when the piston reaches top dead centre, the working fluid is rapidly heated close to critical temperature, as the piston is forced back down the cylinder increasing the volume in the cylinder the working fluid is flashed off, at relatively close to bottom dead centre all the working fluid in the boiler has flashed off to vapour, as the piston reaches bottom dead centre ports in the cylinder wall connecting the cylinder to the condensing chamber are exposed, allowing the higher pressure of the cylinder to pass into said condensing chamber, blowing any condense and residual working fluid off the top of the piston into the condensing chamber, said condensing chamber is in the form of a reservoir and heat exchanger for cooling the working fluid close to * r * ambient atmospheric temperature, as the piston passes bottom dead centre the condenser ports are covered, at this point in the cycle a mechanical or electronic *::: :* injection system sprays an atomise measure of working fluid from the reservoir into the cylinder, this causes the remaining vapour to condense out creating a substantial *. partial vacuum this is acted on by atmospheric pressure and any crankcase pressure, * the working fluid recovers some of the latent heat from the condensing phase change, * : * . said working fluid is further preheated as the dome headed piston accelerates up the cylinder bringing said working fluid into contact with the inner wall of the cylinder, s.. the outer wall of said cylinder is heated by exhaust gas from the burners, at top dead * centre the preheated working fluid is forced into the micro-flash boiler completing the cycle.
2 An external combustion engine in the form of a closed-cycle reciprocating piston engine that uses water or other liquids as a working fluid, said fluid is heated in a micro-flash boiler said boiler is an integral part of the cylinder head, is heated by a parabolic solar reflector acting on the outer wall of said boiler, the inner wall of said boiler has a relatively large surface area achieved by undulations, nodes, fins, or other shapes, the working fluid is forced into said boiler via apertures on the inner wall of the cylinder head, when the piston reaches top dead centre, the working fluid is rapidly heated close to critical temperature, as the piston is forced back down the cylinder increasing the volume in the cylinder the working fluid is flashed off, at relatively close to bottom dead centre all the working fluid in the boiler has flashed off to vapour, as the piston reaches bottom dead centre ports in the cylinder wall connecting the cylinder to the condensing chamber are exposed, allowing the higher pressure of the cylinder to pass into said condensing chamber, blowing any condense and residual working fluid off the top of the piston into the condensing chamber, said condensing chamber is in the form of a reservoir and heat exchanger for cooling the working fluid close to ambient atmospheric temperature, as the piston passes bottom dead centre the condenser ports are covered, at this point in the cycle a mechanical or electronic injection system sprays an atomise measure of working fluid from the reservoir into the cylinder, this causes the remaining vapour to condense out creating a substantial partial vacuum this is acted on by atmospheric pressure and any crankcase pressure, the working fluid recovers some of the latent heat from the condensing phase change, said working fluid is further preheated as the dome headed piston accelerates up the cylinder bringing said working fluid into contact with the inner wall of the cylinder, the outer wall of said cylinder is heated by exhaust gas from the burners, at top dead centre the preheated working fluid is forced into the micro-flash boiler completing the cycle. *... * * * ** * * *** * a S... S. S * . S * S.S* SSSSS * S * S. * S * S *5