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  Recuperator and combustor for use in external combustion engines and system for generating power employing sameUSPTO Application #: 20060093977Title: Recuperator and combustor for use in external combustion engines and system for generating power employing same Abstract: A combustor/recuperator assembly for use in an external combustion engine, such as a Stirling engine. The assembly includes a plurality of substantially hemispherical domed members positioned in nested uniaxial spaced relation, the plurality of substantially hemispherical domed members forming at least a first flow chamber and a second flow chamber, the first flow chamber for passing an incoming charge of air therethrough and the second flow chamber for passing an outgoing charge of combustion exhaust gases therethrough, wherein the second chamber is positioned to be effective to heat the incoming charge of air. Also provided is a system for producing power from a source of liquid fuel. The system is capable of producing up to about 5,000 watts of mechanical or electrical power. (end of abstract) Agent: Michael J. Mlotkowski Roberts, Mlotkowski & Hobbes, PC - Mclean, VA, US Inventors: Roberto O. Pellizzari, Peter Loftus USPTO Applicaton #: 20060093977 - Class: 431215000 (USPTO) Related Patent Categories: Combustion, Heated Line Section Feeds Flame Holder, Distinct Exhaust Products Line Heats Feed Line The Patent Description & Claims data below is from USPTO Patent Application 20060093977. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] This patent application claims priority from Provisional Application Ser. No. 60/484,508, filed on Jul. 1, 2003, the contents of which are hereby incorporated by reference. FIELD [0002] The present invention relates to external combustion engines. More particularly, the invention relates to an external combustion engine, such as a Stirling cycle engine, having a combustor/recuperator assembly design adapted to have improved heat transfer characteristics. BACKGROUND [0003] The Stirling cycle engine was originally conceived during the early portion of the nineteenth century by Robert Stirling. During the middle of the nineteenth century, commercial applications of this hot gas engine were devised to provide rotary power to mills. The Stirling engine was ignored thereafter until the middle of the twentieth century because of the success and popularity of the internal combustion engine. Stirling cycle machines, including engines and refrigerators, are described in detail in Walker, Stirling Engines, Oxford University Press (1980), incorporated herein by reference. [0004] The principle underlying the Stirling cycle engine is the mechanical realization of the Stirling thermodynamic cycle: 1) isovolumetric heating of a gas within a cylinder, 2) isothermal expansion of the gas (during which work is performed by driving a piston), 3) isovolumetric cooling and 4) isothermal compression. Additional background regarding aspects of Stirling cycle machines and improvements thereto are discussed in Hargreaves, The Phillips Stirling Engine (Elsevier, Amsterdam, 1991), incorporated herein by reference. [0005] The high theoretical efficiency of the Stirling engine has attracted considerable interest in recent years. The Stirling engine adds the additional advantages of easy control of combustion emissions, potential use of safer, cheaper, and more readily available fuels and quiet running operation, all of which combine to make the Stirling engine a highly desirable alternative to the internal combustion engine for many applications. [0006] Despite these advantages, development of the Stirling engine has proceeded at a much slower rate than might otherwise be expected. Some of the more acute problems include the need to seal the working gas at a high pressure within the working space, the requirement for transferring heat at high temperature from the heat source to the working gas through the heater head, and a simple, reliable and inexpensive means for modulating the power as the load changes. [0007] One design, which is well suited to a variety of applications, is the free-piston Stirling engine. The free-piston Stirling engine uses a displacer that is mechanically independent of the power output member. Its motion and phasing relative to the power output member is accomplished by the state of a balanced dynamic system of springs and masses, rather than a mechanical linkage. [0008] Stirling engines have been proposed for use in a wide range of applications. Examples include automotive applications, refrigeration systems and applications in outer space. The need to power portable electronics equipment, communications gear, medical devices and other equipment in remote field service presents yet another opportunity, as these applications require power sources that provide both high power and energy density, while also requiring minimal size and weight, low emissions and cost. [0009] To date, batteries have been the principal means for supplying portable sources of power. However, the time required for recharging batteries has proven inconvenient for continuous use applications. Moreover, portable batteries are generally limited to power production in the range of several milliwatts to a few watts and thus cannot address the need for significant levels of mobile, lightweight power production. [0010] Small generators powered by internal combustion engines, whether gasoline- or diesel-fueled have also been used. However, the noise and emission characteristics of such generators have made them wholly unsuitable for a wide range of mobile power systems and unsafe for indoor use. While conventional heat engines powered by high energy density liquid fuels offer advantages with respect to size, thermodynamic scaling and cost considerations have tended to favor their use in larger power plants. [0011] In view of these factors, a void exists with regard to power systems in the size range of approximately 50 to 500 watts. Moreover, in order to take advantage of high energy density liquid fuels, improved fuel preparation and delivery systems capable of low fueling rates are needed. Additionally, such systems must also enable highly efficient combustion with minimal emissions. [0012] The drive to maximize engine efficiency has stimulated the introduction of several modifications to make the Stirling engine more suitable for a broader range of applications. The basic Stirling engine employs a continuous combustion system that can waste considerable energy via exhaust gases released to the atmosphere. For fixed use Stirling engines, heavy steel heat exchangers were devised to return a proportion of the exhaust heat energy to the inducted air to facilitate combustion. In automotive use, the heavy steel heat exchangers were replaced by rotary ceramic pre-heaters of the type, which earlier found utility in gas turbine engine applications. The rotary preheater functioned to expose hot gases through a crescent shaped opening to a rotating ceramic wheel, and separately exposed inducted air to the heated wheel at an independent crescent shaped opening. Small free-piston Stirling engines have provided their own unique challenges in the quest to improve engine efficiency, since inherent size restrictions limit the available options. [0013] In view thereof and despite the advances in the art, there continues to be a need for a small free-piston Stirling engine having improved thermal efficiency characteristics. SUMMARY [0014] Provided is a combustor/recuperator assembly for use in an external combustion engine. The assembly includes a plurality of substantially hemispherical domed members positioned in nested uniaxial spaced relation, the plurality of substantially hemispherical domed members forming at least a first flow chamber and a second flow chamber, the first flow chamber for passing an incoming charge of air therethrough and the second flow chamber for passing an outgoing charge of combustion exhaust gases therethrough, wherein the second chamber is positioned to be effective to heat the incoming charge of air. [0015] Also provided is a burner for an external combustion engine having a heater head. The burner includes a combustor/recuperator assembly for use in an external combustion engine having a heater head, the combustor/recuperator assembly including a plurality of substantially hemispherical domed members positioned in nested uniaxial spaced relation, the plurality of substantially hemispherical domed members forming at least a first flow chamber and a second flow chamber, the first flow chamber for passing an incoming charge of air therethrough and the second flow chamber for passing an outgoing charge of combustion exhaust gases therethrough, a fuel vaporizing device, the fuel vaporizing device including at least one capillary flow passage, the at least one capillary flow passage having an inlet end and an outlet end, the inlet end in fluid communication with a source of liquid fuel; and a heat source arranged along the at least one capillary flow passage, the heat source operable to heat the liquid fuel in the at least one capillary flow passage to a level sufficient to change at least a portion thereof from a liquid state to a vapor state and deliver a stream of substantially vaporized fuel from the outlet end of the at least one capillary flow passage and a combustion chamber defined by an inner surface of the combustor/recuperator assembly and an outer surface of the heater head of the external combustion engine, the combustion chamber having an igniter for combusting the stream of substantially vaporized fuel and air, the combustion chamber in communication with the outlet end of the at least one capillary flow passage, wherein the second chamber of the combustor/recuperator assembly is positioned to be effective to heat the incoming charge of air. [0016] Also provided is a method of generating power. The method includes the steps of inducing a flow of air of through an intake system, supplying liquid fuel to at least one capillary flow passage, causing a stream of substantially vaporized fuel to pass through an outlet of the at least one capillary flow passage by heating the liquid fuel in the at least one capillary flow passage, combusting the air and vaporized fuel in a combustion chamber, exhausting a stream of combustion gases through an exhaust, exchanging heat from the stream of combustion gases exhausted to the flow of air induced for combustion through a recuperator; and converting heat produced by combustion of the vaporized fuel in the combustion chamber into mechanical and/or electrical power using an external combustion engine. The recuperator includes a plurality of substantially hemispherical domed members positioned in nested uniaxial relation, the plurality of substantially hemispherical domed members forming at least a first flow chamber and a second flow chamber, the first flow chamber for passing an incoming charge of air therethrough and the second flow chamber for passing an outgoing charge of combustion exhaust gases therethrough and the second chamber is positioned to be effective to heat the incoming charge of air. BRIEF DESCRIPTION OF THE DRAWINGS [0017] The invention will now be described in more detail with reference to preferred forms of the invention, given only by way of example, and with reference to the accompanying drawings, in which: [0018] FIG. 1 presents a schematic view of a fuel-vaporizing device, combustion chamber and exhaust heat recuperator; [0019] FIG. 2 shows a perspective view of a combustor/recuperator assembly in cross-section, in accordance with an embodiment of the invention; Continue reading... Full patent description for Recuperator and combustor for use in external combustion engines and system for generating power employing same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Recuperator and combustor for use in external combustion engines and system for generating power employing same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. 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