CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This Application claims the benefit of U.S. Provisional Application No. 63/182,205, filed on April 30, 2021, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure is generally related to a system and method for contrail suppression in aero propulsion applications.

BACKGROUND

[0003] Combustion turbines can be used to generate mechanical power and/or electricity. To this end, a combustion turbine can ignite a mixture of fuel and air in order to drive a turbine shaft. A byproduct of the combustion can be the production of heat and water. However, for aero propulsion applications, the presence of water vapors in an exhaust produced by an engine of an aircraft can potentially result in contrails that have an adverse effect on climate conditions and the environment.

SUMMARY

[0004] In accordance with the purpose(s) of the disclosure, as embodied and broadly described herein, the disclosure in one aspect, relates to a system and method of suppressing contrails emitted from an aircraft. Such a system comprises a semi-closed cycle gas turbine engine of an aircraft that exhausts gases in use; a recuperator component that is positioned within an exhaust gas stream of the semi- closed cycle gas turbine engine to remove a portion of the exhaust gas stream in a form of heat energy; and one or more additional heat exchangers in a recirculation path that are configured to condense the heat energy of the portion of the exhaust gas to remove water vapor from the exhaust gas stream.

[0005] Also disclosed herein is a method comprising providing a semi-closed cycle gas turbine engine of an aircraft that exhausts gases in use; removing, via a recuperator component, a portion of the exhaust gas stream in a form of heat energy; receiving, via one or more additional heat exchangers in a recirculation path, the removed exhaust gas stream; condensing the heat energy of the removed exhaust gas stream to form liquid water; and/or internally storing the liquid water thereby suppressing a formation of contrails emitted from the aircraft via the exhaust gas stream.

[0006] In one or more aspects, such systems and methods comprise utilizing the stored liquid water as sanitation water for the aircraft; comprise a storage tank for internally storing liquid water formed from the removed water vapor; wherein the storage tank comprises a fuel tank of the aircraft having a bladder that separates the liquid water from a fuel source for aircraft; wherein the semi-closed cycle gas turbine engine comprises a turbofan jet implementation of the semi-closed cycle gas turbine engine; wherein the semi-closed cycle gas turbine engine comprises a turbojet implementation of the semi-closed cycle gas turbine engine; wherein the semi- closed cycle gas turbine engine is part of an electrical propulsion system for the aircraft; wherein the semi-closed cycle gas turbine engine comprises a high pressure compressor, a high pressure turbine, and a combustor; wherein compressed gas from the high pressure compressor is provided to the recuperator component; and/or comprises directing compressed gas from the high pressure compressor to the recuperator component..

[0007] Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. In addition, all optional and preferred features and modifications of the described embodiments are usable in all aspects of the disclosure taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described embodiments are combinable and interchangeable with one another.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, with emphasis instead being placed upon clearly illustrating the principles of the disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

[0009] FIG. 1 is a drawing of a combined heat and power (CHP) system according to various embodiments of the present disclosure.

[0010] FIGS. 2A-2C are a flowchart illustrating an example of the operation of the CHP system of FIG. 1 according to various embodiments of the present disclosure.

[0011] FIG. 3 is a drawing of another CHP system according to various embodiments of the present disclosure.

[0012] FIG. 4 is a drawing of another CHIP system according to various embodiments of the present disclosure.

[0013] FIG. 5 is a drawing of another CHIP system according to various embodiments of the present disclosure.

[0014] FIGS. 6A-6B are drawings of a turbofan jet engine system with a recuperator according to various embodiments of the present disclosure.

DETAILED DESCRIPTION

[0015] The present disclosure is directed towards power systems that can be used to generate thermal and electrical energy. According to the various embodiments, combined heat and power (CHIP) systems, or cogeneration systems, can generate electricity and useful thermal energy in a single, integrated system. While the various embodiments are directed toward systems that can generate thermal and electrical energy, it is not necessary that all of the generated thermal and electrical energy is utilized. For example, in some embodiments, at least a portion of the thermal and/or electrical energy generated by or accessible from the CHIP may be wasted or not fully utilized. In some embodiments, the thermal energy generated by the CHIP system may be accessible, but wasted or not utilized. In some embodiments, the CHIP system also can capture much of the fresh water that is generated in the combustion process that drives the CHIP system, as well as capture water from the incoming humid air. According to some embodiments, the fresh water that is generated or captured can be used by the CHP system to enhance system efficiency. Such CHP systems have a variety of applications, including aero propulsion applications.

[0016] Many modifications and other embodiments disclosed herein will come to mind to one skilled in the art to which the disclosed systems and methods pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the disclosures are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of this disclosure and to be encompassed by the claims herein.

[0017] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0018] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope of the present disclosure.

[0019] Any recited method can be carried out in the order of events recited or in any other order that is logically possible. That is, unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

[0020] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided herein can be different from the actual publication dates, which can require independent confirmation.

[0021] While aspects of the present disclosure can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the present disclosure can be described and claimed in any statutory class.

[0022] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed compositions and methods belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0023] Prior to describing the various aspects of the present disclosure, the following definitions are provided and should be used unless otherwise indicated. Additional terms may be defined elsewhere in the present disclosure.

[0024] As used herein, “comprising” is to be interpreted as specifying the presence of the stated features, integers, steps, or components as referred to, but does not preclude the presence or addition of one or more features, integers, steps, or components, or groups thereof. Moreover, each of the terms “by”, “comprising,” “comprises”, “comprised of,” “including,” “includes,” “included,” “involving,” “involves,” “involved,” and “such as” are used in their open, non-limiting sense and may be used interchangeably. Further, the term “comprising” is intended to include examples and aspects encompassed by the terms “consisting essentially of” and “consisting of.” Similarly, the term “consisting essentially of” is intended to include examples encompassed by the term “consisting of.”

[0025] As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.

[0026] It should be noted that ratios, concentrations, amounts, and other numerical data can be expressed herein in a range format. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms a further aspect. For example, if the value “about 10” is disclosed, then “10” is also disclosed.

[0027] When a range is expressed, a further aspect includes from the one particular value and/or to the other particular value. For example, where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure, e.g. the phrase “x to y” includes the range from ‘x’ to ‘y’ as well as the range greater than ‘x’ and less than ‘y’· The range can also be expressed as an upper limit, e.g. ‘about x, y, z, or less’ and should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z ’ as well as the ranges of ‘less than x’, less than y’, and ‘less than z \ Likewise, the phrase ‘about x, y, z, or greater’ should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z ’ as well as the ranges of ‘greater than x’, greater than y’, and ‘greater than z’. In addition, the phrase “about ‘x’ to ‘y’”, where ‘x’ and ‘y’ are numerical values, includes “about ‘x’ to about ‘y’”.

[0028] It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a numerical range of “about 0.1% to 5%” should be interpreted to include not only the explicitly recited values of about 0.1% to about 5%, but also include individual values (e.g., about 1%, about 2%, about 3%, and about 4%) and the sub ranges (e.g., about 0.5% to about 1.1%; about 5% to about 2.4%; about 0.5% to about 3.2%, and about 0.5% to about 4.4%, and other possible sub-ranges) within the indicated range.

[0029] As used herein, the terms “about,” “approximate,” “at or about,” and “substantially” mean that the amount or value in question can be the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art such that equivalent results or effects are obtained. In some circumstances, the value that provides equivalent results or effects cannot be reasonably determined. In such cases, it is generally understood, as used herein, that “about” and “at or about” mean the nominal value indicated ±10% variation unless otherwise indicated or inferred. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about,” “approximate,” or “at or about” whether or not expressly stated to be such. It is understood that where “about,” “approximate,” or “at or about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise. [0030] As used herein, the terms “optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0031] With reference to FIG. 1, a CHP system 100 in accordance with various embodiments of the present disclosure, will be described in more detail. According to various embodiments, the CHP system 100 can be used within in an electric grid network that comprises multiple systems that provide electricity for the electric grid. In alternative embodiments, the CHP system 100 can be a stand-alone system that, for example, provides electricity in emergency situations, for loads that do not have access to an electric grid, for military operations (e.g., forward operating bases), and/or other systems.

[0032] Referring to FIG. 1 , according to an embodiment the CHP system 100 can include a turbine system 103, a turbocharger system 106, a refrigeration system 109, and/or other systems. The turbine system 103, the turbocharger system 106, and the refrigeration system 109 can be interconnected using piping, conduit, conductors for power and/or data signals, and/or other components.

[0033] According to the embodiments, the turbine system 103 can include a high pressure compressor 113, a high pressure turbine 116, a combustor 119, a recuperator 123, and/or other components. The high pressure compressor 113 can be a system configured to receive and compress a mixture of fresh air and recirculated combustion products, as will be described in further detail below as part of a semi-closed gas turbine engine arrangement. The combustor 119 can be a system that is configured to combust compressed gases to thereby generate a high- temperature flow of combustion gases. The high pressure turbine 116 of the turbine system 103 can be a system in which combustion gases expand and drive a load, such as a generator. As will be described in further detail below, the recuperator 123 can be an energy recovery system that absorbs heat from combustion products.

[0034] Referring still to FIG. 1, according to the embodiments, the turbocharger system 106 can comprise a low pressure compressor 126, a low pressure turbine 129, and/or other components. The low pressure turbine 129 of the turbocharger system 106 can receive combustion products from by turbine system 103. In addition, the low pressure turbine 129 can drive the low pressure compressor 126 of the turbocharger system 106. In certain alternative embodiments, a turbocharger may not be included as part of the CHP system.

[0035] According to the embodiments, the refrigeration system 109 can be any heat-activated cooling system, such as vapor absorption refrigeration system, or a vapor adsorption refrigeration system, or the like. While several of the embodiments described herein may be described with reference to a vapor absorption refrigeration system, it will be understood that other heat-activated cooling systems can be employed without departing from the scope of the various embodiments. The refrigeration system 109, is described herein with reference to those components which interact with the fluid streams circulating within the CHP system 100 (e.g., the turbine system 103 and the turbocharger system 106). However, it should be understood that the refrigeration system 109 includes one or more additional processes or components (not illustrated) that are associated with the refrigeration cycle. For example, the refrigeration system 109 may include additional systems or processes for circulating and using a refrigerant to accomplish a necessary or desired refrigeration cycle. A non-limiting example of a refrigeration cycle is described in U.S. Patent No. 7,472,550, which is incorporated herein by reference in its entirety, to the extent it is consistent with the present embodiments. In various embodiments, the refrigeration system 109 may include any additional processes or components associated with the refrigeration cycle that provide features not inconsistent with the description of the embodiments herein.

[0036] According to the embodiments, the refrigeration system 109 can comprise a cold gas heat exchanger 133, a hot gas heat exchanger 136, and/or other components. Additionally, a warm gas heat exchanger 139 and a pump 143 may be associated with the refrigeration system 109.

[0037] According to the embodiments, the hot gas heat exchanger 136 of the refrigeration system 109 can receive and absorb and/or transfer heat from combustion products provided by the turbine system 103. The warm gas heat exchanger 139 associated with the refrigeration system 109 can receive and absorb and/or transfer heat from combustion gases provided by the turbocharger system 106 and the hot gas heat exchanger 136. The warm gas heat exchanger 139 can be an intercooler, meaning that it can extract heat from the combustion gases and transfer the heat to an ambient fluid, such as air. In an embodiment, at least a portion of the extracted heat can be used to heat water, such as the water collected from cold gas heat exchanger 133. In various embodiments, at least a portion of the extracted heat can provide a heat load used within the CHP system 100 or externally. The cold gas heat exchanger 133 of the refrigeration system 109 can receive and absorb heat from a mixture of air and combustion products provided by the warm gas heat exchanger 139. In addition, the cold gas heat exchanger 133 can be used to generate cold water, as will be described in further detail below. The pump 143 can be used to pump the generated water to various destinations.

[0038] According to the embodiments, the turbine system 103, the turbocharge system 106, and the refrigerator system 109 of the CHP system 100 are fluidically interconnected, e.g., such that the stream generated by one system is received by one or more of the other systems. Referring to FIG. 1, in one embodiment, the pathways for fresh air, combustion products, and water through the CHP system 100 are illustrated. In particular, the pathways for fresh air and combustion products are shown using dashed lines, and the pathway for water (in liquid and/or gaseous form) are shown using solid lines. Various aspects of the embodiments are described below.

[0039] According to some embodiments, beginning with inlet 146, an inlet stream comprising a mixture of fresh air, steam, and recirculated combustion products is provided to the high pressure compressor 113 of the turbine system 103. Further description regarding this mixture of fresh air and recirculated combustion products is provided below. The high pressure compressor 113 compresses the mixture of fresh air, steam, and recirculated combustion products, and the resultant compressed gases are provided to the cold side of the recuperator 123.

[0040] Referring still to FIG. 1, according to the embodiments, the recuperator 123 heats the compressed gases along with vapor from the refrigerator system 109, and provides the compressed gases, along with vapor, to the combustor 119. At the combustor 119, fuel 149 is combusted using the compressed gases and vapor to generate a stream comprising high-temperature combustion gases. The fuel 149 can include any combustible fuel, such as a hydrocarbon fuel. For most hydrocarbon fuels, the resulting combustion gases will comprise carbon dioxide and water (in the form of water vapor) along with lesser amounts of other gaseous products. These high-temperature combustion gases are provided to the high pressure turbine 116, where the combustion gases expand, driving a generator and/or any other type of mechanical load. In this way, the turbine system 103 may produce mechanical power and/or electricity for one or more loads.

[0041] According to the embodiments, the combustion products resulting from the high pressure turbine 116 are provided to the hot side of the recuperator 123, which absorbs heat from the combustion products (and exchanges the heat with the cold side of the recuperator 123). The resulting combustion product stream is then provided as an input stream to the turbocharger system 106 and the refrigeration system 109. For example, the combustion product stream from the recuperator 123 may be divided into a first portion that is received as an input stream to the turbocharger system 106 and a second portion that is received as an input stream to the refrigeration system 109. The proportion of the first and second portions of the combustion product stream can be controlled and modified to produce any necessary or desired result.

[0042] According to the embodiments, a first portion of the combustion products from the turbine system 103 is provided as an input stream to the low pressure turbine 129 of the turbocharger system 106. The combustion products provided to the low pressure turbine 129 drive the low pressure compressor 126. Additionally, exhaust is emitted from the low pressure turbine 129 at outlet 153. By way of example, the exhaust at outlet 153 may be vented to the atmosphere, or recycled, or treated further. [0043] In some embodiments, fresh air is provided at inlet 156 to the low pressure compressor 126 of the turbocharger system 106. In some embodiments, the fresh air may be filtered. In some embodiments, the inlet 156 may be sound damped. The low pressure compressor 126 then compresses the fresh air to provide an outlet stream comprising the compressed fresh air. In some embodiments, the fresh air is compressed by a factor of five. As a non-limiting example, if the atmospheric pressure is 1.0 atm, the low pressure compressor 126 compresses the fresh air to a pressure of 5.0 atm. The low pressure compressor 126 may compress the fresh air at other factors in other embodiments. According to the various embodiments, the compressed fresh air can be provided as an input to the refrigeration system 109. In some embodiments, the compressed fresh air can be combined with one or more combustion products at mixing point 159. The compressed fresh air can also be mixed with the recirculator products between the warm gas heat exchanger 139 and the cold gas heat exchanger 133.

[0044] According to the embodiments, a second portion of the combustion products from the turbine system 103 is provided to the refrigeration system 109. In particular embodiments, this second portion of the combustion products is provided to the hot gas heat exchanger 136, which absorbs heat from the combustion products, providing an output stream of cooled combustion products. The heat from combustion products provided to the hot gas heat exchanger also drives the refrigeration system 109.

[0045] The cooled combustion products exiting hot gas heat exchanger 136 may then be combined at mixing point 159 with compressed fresh air provided by the low pressure compressor 126 of the turbocharger system 106. In some embodiments the cooled combustion products and compressed fresh air are mixed at a 3-to-1 ratio of combustion products to fresh air. The cooled combustion products and compressed fresh air may be mixed at other ratios and/or at other points in the flow path in other embodiments.

[0046] Referring still to FIG. 1, according to the embodiments, the mixture of cooled combustion products and compressed fresh air is then provided to the warm gas heat exchanger 139. The warm gas heat exchanger 139 absorbs heat from the mixture of combustion products and fresh air, providing a cooled mixture of combustion products and fresh air. This absorbed heat may be provided to external systems. Additionally, this heat can be used to heat water within the CHP system 100, as will be described in further detail below. Additionally, heat absorbed by the refrigeration system 109 can also be used to heat water.

[0047] According to the embodiments, the cooled mixture of combustion products and fresh air resulting from the warm gas heat exchanger 139 is provided as an input to the cold gas heat exchanger 133. The cold gas heat exchanger 133 absorbs heat from the mixture of combustion products and fresh air, providing a chilled mixture of combustion products and fresh air. In some embodiments, the refrigeration system 109 may comprise an additional heat exchanger (not shown) for which refrigerant associated with the cold gas heat exchanger may be used to cool an external load.

[0048] According to the embodiments, the chilled mixture of combustion products and fresh air from the cold gas heat exchanger 133 of the refrigeration system 109 is then provided to the inlet 146 of the high pressure compressor 113, as described above. According to the embodiments, the chilled mixture of combustion products and fresh air may result in an improved cycle thermodynamic efficiency relative to other systems that do not provide a chilled mixture of combustion products and fresh air. In some embodiments, the chilled mixture may comprise a ratio of combustion products to fresh air that is about 1:1 to about 4:1 , or about 3:1. In some embodiments, the fuel-air equivalence ratio (cp), which is a ratio of the fuel-to-oxidizer ratio for the system to a stoichiometric fuel-to-oxidizer ratio, is about 0.7 to about 0.95, or about 0.9. In some embodiments, the chilled mixture may comprise a ratio of combustion products to fresh air that provides a necessary or desired fuel-air equivalence ratio.

[0049] In some embodiments, the temperature of the chilled mixture may be between about -15°C and about 15°C. In some embodiments, the temperature of the chilled mixture is less than about 15°C, or less than about 10°C, or less than about 5°C. In some embodiments, the temperature of the chilled mixture may be approximately 3 °C. In some embodiments in which the temperature of the chilled mixture is sub-freezing, a heat exchanger may be used to avoid ice formation, for example, a direct heat exchange process using a glycol loop.

[0050] In some embodiments, the pressure of the chilled mixture may be greater than about 2 atm, or greater than about 3 atm or greater than about 4 atm, In some embodiments, the pressure of the chilled mixture may be from about 2 atm to about 6 atm, or from about 3 atm to about 5 atm. In some embodiments, the pressure of the chilled mixture may be approximately 3 atm. In some embodiments, the pressure of the chilled mixture may be dependent, at least in part, upon the equipment specifications of the turbocharger system 106. Generally speaking, a more efficient turbocharge system 106 can provide a higher delivered pressure. According to the embodiments, the turbocharger system 106 or the components thereof can be selected to provide any necessary or desired result. The chilled mixture of combustion products and fresh air may have other characteristics in other embodiments.

[0051] According to the various embodiments, when the cold gas heat exchanger 133 operates to, for example, chill the mixture of combustion products and fresh air, fresh water may condense on or near the cold gas heat exchanger 133. This condensed fresh water may be collected and provided to external systems. In other embodiments, the condensed fresh water produced by cold gas heat exchanger 133 may be provided to one or more other systems within the CHP 100. In some embodiments, the fresh water may be provided to the pump 143, which may increase the water pressure.

[0052] In some embodiments, make-up water may optionally be added to the CHP system 100, such as, for example, to compensate for water losses elsewhere in the system. In some embodiments, the make-up water may be introduced to the system at the refrigeration system 109. For example, the make-up water may be combined with the condensed fresh water produced by the cold gas heat exchanger 133.

[0053] In some embodiments, the fresh water produced by cold gas heat exchanger 133 may then be provided as an input to the warm gas heat exchanger 139 and/or the refrigeration system 109. Heat from the warm gas heat exchanger 139 can increase the temperature of this fresh water. This heated water may be provided to external systems. In some embodiments, the heated water is provided from the warm gas heat exchanger 139 to the hot gas heat exchanger 136, which further increases the temperature of the fresh water, generating steam. In some embodiments, the steam generated by the hot gas heat exchanger 136 may be provided to external systems. In some embodiments, the steam generated by the hot gas heat exchanger 136 may be provided to one or more systems within the CHP 100. For example, referring to FIG. 1, in some embodiments, the steam from the hot gas heat exchanger 136 of the refrigeration system 109 is provided to the recuperator 123 of the turbine system 103.

[0054] In alternative embodiments, hot gas heat exchanger 136, generates a hot water stream (in liquid form) rather than steam. In these embodiments, instead of the refrigeration system 109 providing steam to the recuperator 123, the refrigeration system 109 can provide hot water in liquid form to the recuperator 123. In some embodiments, the hot water in its liquid form can be evaporated, such as in a saturator that causes the liquid water to evaporate, and the resulting steam can be mixed with the compressed gases from the high pressure compressor 113.

[0055] According to the embodiments, at the recuperator 123, the steam (either from the hot gas heat exchanger 136 or from a saturator) is combined with the mixture of combustion products and fresh air from the high pressure compressor 113 of the turbine system 103 to provide a humid mixture of combustion products and fresh air. This humid mixture is then heated in the recuperator 123, and the heated mixture is provided as an input to the combustor 119, where the heated mixture and fuel 149 are combusted, producing a humid mixture of combustion products. Use of a humid mixture of combustion products at the combustor 119 may result in combustion that is more efficient relative to systems that do not provide a humid mixture of combustion products for combustion. [0056] According to the various embodiments described herein, the CHP system 100 may provide several benefits relative to conventional systems. For example, the CHP system 100 described herein may have a higher “on” design efficiency as compared to conventional turbine systems due at least in part to the relatively low temperature of the input stream entering the turbine system 103. In addition, the CHP system 100 may have a higher “off” design efficiency relative to conventional turbine systems due at least in part to the ability to maintain the turbine system 103 at a relatively fixed set of temperature states. Additionally, the CHP system 100 may be more reliable, quieter, have a lower cost of materials, have a faster time response, and have lower emissions levels relative to conventional systems.

[0057] With reference to FIGS. 2A-2C, the operation of the CHP system 100 of the various embodiments, is further illustrated with a flowchart. It is understood that the flowcharts of FIGS. 2A-2C provide merely one example, among others, of the operation of the CHP system 100. Although the flowchart of FIGS. 2A-2C illustrate a specific order of operation, the order of execution may differ from that which is depicted. For example, in some embodiments the order of performance of two or more boxes may be switched relative to the order shown, without departing from the scope of the embodiments. In some embodiments, two or more boxes shown in succession in FIGS. 2A-2C can be performed concurrently or with at least partial concurrence. Further, in some embodiments, one or more of the boxes shown in FIGS. 2A-2C can be skipped or omitted.

[0058] Referring to FIGS. 1 and 2A, beginning with box 203, the high pressure compressor 113 is provided with a mixture of fresh air and recirculated combustion products in a semi-closed arrangement. At box 206, the mixture of fresh air and recirculated combustion products is compressed using the high pressure compressor 113. The compressed gases are then provided from the high pressure compressor 113 to the cold side of the recuperator 123, as shown at box 209.

[0059] At box 213 the recuperator 123 heats the received compressed gases. The heated gases are then provided from the recuperator 123 to the combustor 119, as shown at box 213. As indicated at box 216, the heated gases are then provided from the recuperator 123 to the combustor 119, and the combustor 119 then combusts the compressed gases, as shown at box 219. At box 223, the combustion gases from the combustor 119 are then provided to the high pressure turbine 116.

[0060] At box 226, the high pressure turbine 116 drives a load, such as a generator, as a result of the combustion gases expanding in the high pressure turbine 116. The combustion products are also provided from the high pressure turbine 116 to the hot side of the recuperator 123, as indicated at box 229.

[0061] Referring to FIGS. 1 and 2B, at box 233, combustion products are provided from the hot side of the recuperator 123 to the low pressure turbine 129 of the turbocharger system 106 and also to the hot gas heat exchanger 136 of the refrigeration system 109. As indicated at box 236, the hot gas heat exchanger 136 absorbs heat from the provided combustion products and drives the refrigeration system 109. At box 239, the low pressure turbine 129 uses the provided combustion gases to drive the low pressure compressor 126, and the low pressure compressor 126 compresses fresh air, as shown at box 243. The compressed fresh air is then mixed with the combustion products from the hot gas heat exchanger 136, as indicated at box 246.

[0062] As shown at box 249, the mixture of the combustion products and compressed fresh air is provided to the warm gas heat exchanger 139. The warm gas heat exchanger 139 then absorbs heat from the received mixture of combustion products and compressed air, as shown at box 253, and the absorbed heat is used by the warm gas heat exchanger 139 to heat water to thereby generate steam, as shown at box 256.

[0063] Referring to FIGS. 1 and 2C, at box 259, the mixture of combustion products and fresh air are provided from the warm gas heat exchanger 139 to the cold gas heat exchanger 133, where the cold gas heat exchanger 133 absorbs heat from the received mixture, as indicated at box 263. Then, as shown at box 266, the chilled mixture of combustion products and fresh are is provided from the cold gas heat exchanger 133 to the high pressure compressor 113. As a result of the cold gas heat exchanger 133 absorbing heat, water condenses on or near the cold gas heat exchanger 133, as shown at box 269.

[0064] As indicated at box 273, the condensed water is provided to the warm gas heat exchanger 139 and the hot gas heat exchanger 136 to produce steam. At box 276, the steam is provided to the recuperator 123. The steam is then combined with the mixture of combustion products and fresh air in the combustor 119, as shown at box 279. Thereafter, the process ends.

[0065] Referring now to FIG. 3, in another embodiment of the disclosure, a CHIP system 300 is similar to the CHIP system 100 shown in FIG. 1. Flowever, for the CHP system 300, the turbine system 103 also includes a saturator 303 in fluid communication with the high pressure compressor 113, the hot gas heat exchanger 136, and the recuperator 123. In this embodiment, the hot gas heat exchanger 136 of the refrigeration system 109 produces hot water rather than steam. Referring to FIG. 3, the hot water is provided as an input to the saturator 303. The saturator 303 can cause the received hot water to evaporate. The resultant steam canbe mixed with the compressed gases from the high pressure compressor 113. The mixture of evaporated water and compressed gases is then provided to the recuperator 123.

[0066] Referring now to FIG. 4, in yet another embodiment, the turbine system 103 of CHIP system 400 also integrates a fuel cell 403 before the combustor 119. According to this embodiment, the inputs to the fuel cell 403 include compressed gas from one of the CHIP systems, e.g., compressed gas from the recuperator 123, and compressed fuel 401 (e.g., natural gas or nearly any syngas compatible with the fuel cell 403). The outputs of the fuel cell 403 include electric power and hot depleted oxidizer and fuel streams.

[0067] In some embodiments, the fuel cell 403 includes a cooling circuit (not shown). In these embodiments, steam or hot water from the hot gas heat exchanger 136 can be provided as a coolant to the cooling circuit of the fuel cell 403. In an embodiment, the coolant is hot water, and the hot water can evaporate while cooling the fuel cell 403, and the steam can then be mixed with the compressed gases and fed to the recuperator 123. In an embodiment, the coolant is steam, and the steam is superheated while cooling the fuel cell 403, and the superheated steam can then be mixed with the compressed gases and fed to the recuperator 123. [0068] In various aspects, the fuel cell 403 can be a fuel cell capable of operating at a high temperature (“high-temperature fuel cell”). Exemplary, but non limiting examples of such a fuel cell include a solid oxide fuel cell (also referred to as a SOFC), a molten carbonate fuel cell (also referred to as a MCFC), a high- temperature proton exchange membrane fuel cell (also referred to as a HT - PEMFC), a tubular solid oxide fuel cell (also referred to as a TSOFC), a protonic ceramic fuel cell, a direct carbon fuel cell, a phosphoric-acid fuel cell (also referred to as a PAFC), or a planar solid oxide fuel cell. The disclosed CHIP system 400 comprising a fuel cell 403 also contemplates integration of other high operating temperature fuel cells that becoming available in the future. It is to be understood that “high operating temperature” refers to a working temperature of the fuel cell of at least about 100 °C, at least about 110 °C, at least about 120 °C, at least about 130 °C, at least about 140 °C, at least about 150 °C, at least about 160 °C, at least about 170 °C, at least about 180 °C, at least about 190 °C, at least about 200 °C, at least about 250 °C, at least about 300 °C, at least about 350 °C, at least about 400 °C, at least about 450 °C, at least about 500 °C, at least about 550 °C, at least about 600 °C, at least about 650 °C, at least about 700 °C, or any range of temperatures comprising any of the foregoing values or any combination of the foregoing values. In a further aspect, the fuel cell 403 operates in a temperature range compatible with the operation of the high pressure turbine 116.

[0069] Before proceeding to the Examples, it is to be understood that this disclosure is not limited to particular aspects described, and as such may, of course, vary. Other systems, methods, features, and advantages of foam compositions and components thereof will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of this disclosure and to be encompassed by the claims herein.

EXAMPLES

[0070] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and/or methods claimed herein are made and evaluated, and are intended to be purely exemplary of the disclosure and are not intended to limit the scope of what the inventors regard as their disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in Kelvin or is at ambient temperature, and pressure is at or near atmospheric.

Example 1: Design-Point Efficiency Calculation

[0071] In this example, the calculation of the design-point efficiency of an exemplary CHP, will be described with reference to FIG. 5, in which CHP system 500 includes a turbine system 103, a vapor absorption refrigeration system 109, and a turbocharger system 106, consistent with the embodiments described herein. Referring to FIG. 5, various State points for the various streams throughout the CHP system 500 are designated with reference numbers 1 through 9, and w1 through w5. These State points are specifically referenced in the calculation.

[0072] The design of the plant typically involves a high-level optimization, trading off component size, materials, and cost against the overall objective, which is often life cycle costs constrained by limits on emissions, plant footprint, noise, etc. For this example, turbomachinery efficiencies have been chosen typical of gas turbines of a few megawatts, combined heat exchanger/piping losses and effectivenesses appropriate for systems optimized without significant size constraints, and the fuel mass flow is neglected in comparison to the combustor inlet flow. Table 1 shows the input parameter values used in this example.

Table 1. Input parameters for example design-point case. [0073] Referring to FIG. 5, for this example, the steam flow at State w5 (between hot gas heat exchanger 136 and the recuperator 123) is taken to be 20% of the total flow at State 3.2 (within the recuperator 123). This is a reasonable ratio for wet cycles and could be higher, limited only by the capacity of the vapor absorption refrigeration system 109 to provide sufficient cooling capacity to condense the water at State w1 and cool the gas flow at State 3 to the target temperature of 3°C.

[0074] The turbine system 103 is the only part of the cycle of CHP 500 in which net power is produced, so by using the assumption of thermally perfect gas, to find the cycle efficiency, it is only necessary to determine the temperatures in that block 103. For this estimate, the specific heat ratio is approximated based on local temperature and composition, with values of 1.35 (States 3, 3.1), 1.33 (States 3.2, 3.3), and 1.3 (States 4, 5, 6, 9).

[0075] As shown in Table 1, the high pressure turbine 116 (FIPT) inlet and outlet temperatures are each specified, based on material limits in the turbine 116 and recuperator 123. With these known, the FIPT pressure ratio can be calculated and, using the design relative pressure drops in the heat exchangers and combustor 119, the FIPC pressure ratio can be calculated. This allows a straightforward calculation of the required temperatures.

[0076] a) High Pressure Turbine pressure ratio

[0077] From the definition of turbine polytropic efficiency, the turbine pressure ratio can be calculated from the following Equation (I): Equation (I)

[0001] Substituting the specified values of temperatures, efficiency, and specific heat ratio for CHP 500 yields a turbine pressure ratio of 4.26.

[0002] b) High Pressure Compressor pressure ratio

[0003] The HPC pressure ratio is found by forming an identity:

Equation (II)

[0004] Each ratio on the right side of Equation (II) is known from the relative pressure drop, except the previously-calculated HPT pressure ratio. Substituting input values, the HPC pressure ratio is 4.73.

[0005] c) Recuperator Cold-Side Inlet Temperature

[0006] The temperatures at States 6 and 9 are equal, ignoring the small heat loss in the duct. The steam temperature at State w5 (Tws) approaches that of State 9; temperature at State 3.2 (T3.2) approaches that of State 6. Therefore, Tws is very close to T3.2. That implies that both must equal the temperature at State 3.1 (T3.1).

[0007] d) High Pressure Compressor exit temperature.

[0008] From the definition of compressor polytropic efficiency, the following Equation (III) can be utilized:

Equation (III) [0009] Taking T3 as 276 K, one obtains T3.I=432 K. As discussed above, T3.1 is also the approximate value of T3.2.

[0010] e) Recuperator exit temperatures

[0011] With the temperature values at States 3.2 and 5 being 432 K and 1250 K, respectively, and the recuperator effectiveness taken as 0.92, the recuperator exit states may now be calculated. Assuming the cold stream to have the minimum heat capacity, the following Equation (IV) can be utilized: Equation (IV)

[0012] Inserting values yields T3.3=1 185 K. Similarly, an energy balance yields Te=497 K.

[0013] f) Cycle Efficiency

[0014] The cycle efficiency may now be calculated from the known state temperatures, using Equation (V):

Equation (V)

[0015] where G is the product of mass flow rate and specific heat. The mass flow rate at 3.3 and 4 is the same; mass flow rate at 3 is 80% of that at 3.3 (due to 20% steam injection). C _P ratios are calculated from the assumed values of specific heat ratio. The calculation yields an efficiency of 70.7%.

[0016] The cycle efficiency is sensitive to the recuperator effectiveness. For instance, repeating the calculation as above but with effectiveness decreased to 80% results in a cycle efficiency close to 60%. Note that this is still a remarkably high value, nearly 15% higher than the cycle without the water cycle addition, which in turn is about 10% higher in efficiency than the state of the art.

[0017] While semi-closed cycle gas turbine engines are power or propulsion systems that use conventional components such as compressors, turbines, and heat exchangers, but with part of the post-combustion flow recirculating to join the incoming air as part of the working fluid, such engines have the potential in aero propulsion applications to enhance the efficiency and reduce overall weight attributable to the aero propulsion system (i.e. engine, fuel, and structure for supporting them).

[0018] For aero propulsion applications, aero engines with heat exchangers have been proposed and prototyped, in which the heat exchanger is integrated or installed in an exhaust nozzle of the aircraft engine and operates as a heat recuperator that uses turbine exhaust gas to preheat air that is being introduced to a combustion chamber. But, the heat exchanger weight has so far limited the concept and development of aero engines having heat exchangers. However, a heat exchanger for a semi-closed cycle turbine system of the present disclosure can operate at high pressures, making the design much more compact. Hence, the performance gain may come with a weight penalty small enough to justify the approach.

[0019] A semi-closed cycle flow path for aero propulsion applications, in accordance with embodiments of the present disclosure, is unconventional, allowing exhaust gases to be cooled enough to condense the water vapor and store the condensed water onboard, so that the water is not allowed to condense externally for a contrail. Additionally, in accordance with embodiments of the present disclosure, water can be condensed via a cooler assembly 609 (FIG. 6A) at an elevated pressure which means that a high percentage of the water vapor can be condensed. Further, the incorporation of heat exchangers (that are relatively high pressure and compact) means less weight which is advantageous, since weight and size are critical for flight systems. Principals of capturing water generated in a combustion process, via heat exchangers of a cooler assembly, such as that of a semi-closed cycle gas turbine engine, are consistent with and follow the teachings of the present disclosure. In various embodiments, an exemplary cooler assembly 609 (FIG. 6A) can include heat exchanger components 133, 136, 139 and/or other components of the refrigeration system 109 for a combined heat and power (CHP) system. In general, the cooler assembly 609 does not require a vapor absorption refrigeration system (VARS), since no cooling is needed at altitude and the VARS adds unneeded weight to the aircraft, as an inlet diffuser and nozzle components can serve similar functions and as heat waste can be directed into a fan bypass stream.

[0020] In accordance with embodiments of the present disclosure, a semi- closed cycle gas turbine engine is provided with additional novel features. In the present disclosure, one key point relates to reducing the contrail emitting from an aircraft, which is due to water vapor condensing as the engine exhaust cools while interacting with the cold air at high altitude, which can adversely affect atmospheric conditions.

[0021] In general, water vapor is produced in the combustion of hydrocarbon fuels or hydrogen. In the semi-closed cycle of a gas turbine, most of the water vapor can be condensed internal to the engine within a recirculation path. In accordance with various embodiments of the present disclosure, this internal water can be removed from the gas path by a liquid water removal (LWR) system 606 and used onboard or stored to avoid contrails, then emptied at low altitude or after landing. Accordingly, a pump can be used to direct condensed water from the cooler assembly to a storage location 608. Various onboard uses include, but are not limited to, sanitation/toilets, drinking, etc. In accordance with various embodiments, a convenient storage location 608 (FIG. 6A) can include fuel tanks, e.g., using a bladder to keep fuel and water separate. Additionally, in various embodiments, water from the storage location 608 can be pumped (via pump 143) at high pressure and mixed with an input stream (at state 6 and/or state 7) before the stream is input to the combustor 119. While this use of the repurposed water will reduce the contrail reduction effect, it will increase efficiency and allow direct combustion of hydrogen (liquid or gaseous) more effectively (resulting in lower emissions).

[0022] In various embodiments, the semi-closed cycle gas turbine engine may encompass various implementations, such as a turbofan jet, turbojet, etc., in which a heat exchanger is integrated or installed before an exhaust nozzle of the aircraft engine and operates as a heat recuperator that uses a recirculating portion of turbine exhaust gas, via a recirculation path, to preheat air that is being introduced to a combustion chamber (which may have additional heat exchangers in the recirculation path), in accordance with the present disclosure.

[0023] In the diagram of FIG. 6A, various states or stages of an exemplary embodiment of a turbofan jet engine system 600 with a recuperator 123 are shown. Various State points for the various streams throughout the system 600 are designated with reference numbers 1 through 12.2. The middle/bottom portion of the figure shows a flow of air through a core nozzle via the turbine engine of the turbojet portion of the system; and the top portion shows the bypass flow of air around the core nozzle and exiting a fan nozzle via a cooler component 609. In various embodiments, different arrangements of bypass and/or core flow streams may be featured.

[0024] Accordingly, in the arrangement of FIG. 6A, states 1, 4 show incoming ambient air flow from an inlet diffuser of a turbofan jet system as streams of air are being introduced to a fan 604, and states 2, 5 show the corresponding streams of compressed air after passing through the fan 604.

[0025] In particular, stream 2 is introduced to the cooler component 609 as part of a parallel flow of streams through the cooler component 609 that exits a fan nozzle (at state 3) after being passed through the cooler component 609. In the opposite direction, a recirculating stream cools from state 11 to state 12 (via the cooler assembly 609 at the top of the diagram), giving heat up to the fan bypass stream (at states 2 and 3), thereby resulting in water vapor (at state 12) that is condensed internal to the engine within the recirculation path (at state 12.1) which reduces the contrail that forms from outtake air that exits from the core nozzle (at state 10). At the same time, the cooler 609 heats the fan bypass stream which provides more thrust as the fan bypass stream exits the fan nozzle (at state 3).

[0026] Referring to the middle/bottom portion of the figure, state 5 shows a stream of compressed air (via the fan 604 that takes incoming air at state 4) that is introduced to a compressor 113. For the stream of air flowing through the core nozzle, the fan 604 and compressor 113 act as stages of core compression to the core stream. Accordingly, state 6 shows compressed gases after passing through the compressor 113 and before being received by a recuperator 123, state 7 shows heated compressed gas after being passed through the recuperator 123 and before being received by a combustion chamber 119, state 8 shows the combusted gas mixture after passing through the combustion chamber 119 and before being received by the high pressure turbine 116, and state 9 shows the compressed gas mixture after passing through the high pressure turbine compressor 116. State 9.1 shows a portion of the compressed gas from the high pressure turbine 116 being recirculated and passed to the recuperator 123, state 9.2 shows a portion of the compressed gas from the high pressure turbine 116 being passed to an optional low pressure turbine 129. The proportion of the first and/or second portions of the compressed gas stream can be controlled and modified to produce any necessary or desired result. Next, state 10 shows exhaust gas from the optional low pressure turbine 129 being expelled out of a core nozzle of the turbofan jet system. Accordingly, in various alternative embodiments, the low pressure turbine 129 can be omitted such that the stream (at state 9.2) can be output as exhaust (at state 10) through the core nozzle. The stream (at state 11 ) that is output from the recuperator 123 is provided as an input stream to the cooler 609. The recirculating stream cools from state 11 to state 12 (via the cooler assembly 609), giving heat up to a fan bypass stream (that takes incoming air (state 1) from the inlet which is taken in by the fan 604 and is introduced to the cooler at state 2), thereby resulting in water vapor (at state 12) that is condensed internal to the engine within a recirculation path (at state 12.1) which reduces the contrail that forms from outtake air that exits from the core nozzle (at state 10). Accordingly, water is naturally condensed in the process from state 11 to 12 (as shown by the arrow in the diagram at state 12.2 to liquid water via a liquid water removal (LWR) assembly 606) and the separation of the liquid/water reduces the amount of water vapor in the exhaust at state 10, suppressing contrail formation from a core nozzle of the aeroengine. It is noted that the diagram shows one possible aeroengine configuration and that other engine configurations are contemplated by the present disclosure. Additionally, in certain embodiments, certain system components (e.g., low pressure turbine 129) may be optional such that a portion of the compressed gas from the high pressure turbine 116 (at state 9.2) may exit from the core nozzle as exhaust.

[0027] For example, FIG. 6B is an alternative implementation that is similar to FIG. 6A, but with the following changes in flows where water from the liquid water removal assembly 606 is routed to cooling passages in the turbine (e.g., high pressure turbine 116 via a pump 143 in order to cool the hot passages of the turbine. This will help increase cycle efficiency and power because it reduces or eliminates the need for cooling air to be removed from the discharge of the high pressure compressor. After the cooling water is output from the turbine (e.g., at high pressure turbine 116), where the water may be steam due to its serving as a coolant, and re-introduced at state 6 (before the recuperator) and/or state 7 (before the combustor), as indicated in the figure.

[0028] As another non-limiting, in a turbojet implementation, there is no fan (no bypass stream), so the heat can be absorbed by something other than a cooler 609. For example, if the Mach number is reasonable low (such as less than 2), ram air can cool the recirculation stream (instead of endothermic fuel), thereby resulting in water vapor that is condensed internal to the engine within the recirculation path which reduces the contrail. As such, ram air may be brought into the engine from the freestream for the specific purpose of cooling.

[0029] Alternatively, if the Mach number is high, endothermic fuels are sometimes used as coolant, so the heat could be absorbed using the coolant, thereby resulting in water vapor that is condensed internal to the engine within the recirculation path which reduces the contrail. While reduction of the contrail in the turbojet implementation would be less (as compared to the turbofan jet implementation) since the cooling by endothermic fuel would not reduce the gas temperature as much as a fan stream would, the net performance effect is that a higher Mach number operation would be possible, because the smaller exit mass flow would be more energetic than the exhaust (nozzle) flow of a traditional turbojet.

[0030] For electric propulsion, in which all but the smallest aircraft use an engine that acts as a generator and the engine is hybridized with batteries (like a hybrid car), the engine’s exhaust still produces a contrail, although the engine does not produce thrust. In such implementations, a heat exchanger can be deployed to internally remove water vapor from the exhaust emitted from the aircraft, in accordance with embodiments of the present disclosure.

[0031] The above-described embodiments are merely examples of implementations to set forth a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiments without departing substantially from the principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure.