Jet reference fluid formulations for fuel substitutes and methods thereof

Abstract

The invention relates to jet reference fluid formulations for fuel substitutes and methods thereof. Jet reference fluid (JRF) compositions and their use in test methods are disclosed. The jet reference fluid comprises a first hydrocarbon and a second hydrocarbon, and wherein the first hydrocarbon and the second hydrocarbon may or may not comprise an aromatic compound. The jet reference fluid (JRF) composition may include one or more additives, such as ethylene glycol monomethyl ether. A method for testing compatibility of jet reference fluid (JRF) with aviation fuel is also disclosed. The method may be used to assess one or more components or systems of aerospace vehicles, including thermosets, thermoplastics, sealants, elastomers, metals, veneers, coatings, wiring, or combinations thereof.

Description

[0001] Related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 564,762, filed on March 13, 2024, and U.S. Application No. 19 / 045,182, filed on February 4, 2025, which are hereby incorporated by reference in their entirety. Technical Field

[0003] The present teachings generally relate to the evaluation of aerospace component exposure to fuels and, more particularly, to a jet reference fluid formulation for testing aerospace component exposure to fuels. Background Art

[0004] Current systems and materials on aircraft are designed for use with conventional jet fuel compositions. There is an aviation industry goal to use more sustainable aviation fuels (SAFs) and fuel sources, up to and including 100% sustainable aviation fuel (SAF). In order to move to cleaner and more efficient fuels, which may not have some of the chemical components of petroleum-based jet fuel, it is necessary to conduct extensive testing to ensure that systems and materials are compatible with the proposed SAF formulation or composition. This can include testing anything on the aircraft that comes into contact with the fuel, such as primers, sealants, finishes, metals, composites, and O-rings, for example.

[0005] Sustainable aviation fuel (SAF) is designed to be an alternative fuel that reduces the environmental impact of their use in aviation by reducing greenhouse gas emissions compared to traditional jet fuel. SAF can be produced or refined by renewable resource components (such as biomass, waste materials or other carbon capture technologies). Blending SAF with traditional jet fuel or completely replacing traditional jet fuel can obtain additional flexibility. The chemical properties of jet fuel (including SAF) can have a certain range of compositions, and therefore have a certain range of characteristics, and the impact produced is twofold: petroleum-derived jet fuel can have a certain range of compositions, including 0% aromatic compounds, while SAF or synthetic fuels may lack all chemical categories that may be present in jet fuel, including aromatic compounds and sulfur impurities or nitrogen impurities, and these chemical substances may affect the materials they contact. Examples may include mercaptans that can be found in crude oil, which can affect the sealants in aerospace vehicles (vehicles, aircraft).

[0006] Therefore, it is desirable to have available standards, materials, and methods to better understand and classify the compatibility of available SAFs with existing or proposed aviation components. It is important to be able to evaluate the range of potential fuel compositions, as well as the boundary conditions under which fuel compositions relate to material or system performance. Summary of the Invention

[0007] The following is presented as a simplified summary to provide a basic understanding of some aspects of one or more embodiments of the present teachings. This summary is not an extensive overview, nor is it intended to identify key or important elements of the present teachings, nor is it intended to describe the scope of the present disclosure. Instead, its primary purpose is simply to present one or more concepts in a simplified form as a prelude to the detailed description that will be presented later.

[0008] The present invention discloses a Jet Reference Fluid (JRF) composition. The Jet Reference Fluid comprises a first hydrocarbon and a second hydrocarbon, wherein the first hydrocarbon and the second hydrocarbon may not contain aromatic compounds. A method for producing the Jet Reference Fluid (JRF) composition includes: wherein the first hydrocarbon may comprise isooctane or the second hydrocarbon may comprise n-heptane. The first hydrocarbon may be present in an amount of approximately 1% to approximately 20% by weight, based on the total weight of the Jet Reference Fluid. The second hydrocarbon may be present in an amount of approximately 50% to approximately 90% by weight, based on the total weight of the Jet Reference Fluid. The Jet Reference Fluid (JRF) composition may comprise glycol monomethyl ethers, including ethylene glycol monomethyl ether, 2-(2-methoxyethoxy)ethanol (DiEGME), and the like. The glycol monomethyl ethers, including ethylene glycol monomethyl ether, 2-(2-methoxyethoxy)ethanol (DiEGME), and the like, may be present in an amount of approximately 0.1% to approximately 10% by weight, based on the total weight of the Jet Reference Fluid.

[0009] The present invention discloses another Jet Reference Fluid (JRF) composition, wherein the Jet Reference Fluid comprises a first hydrocarbon and a second hydrocarbon, wherein one of the first hydrocarbon and the second hydrocarbon may comprise one or more aromatic compounds. A method for implementing the Jet Reference Fluid (JRF) composition may include: wherein the first hydrocarbon comprises toluene or the second hydrocarbon comprises isooctane. The Jet Reference Fluid (JRF) composition may further comprise cyclohexane or n-heptane.

[0010] The present invention discloses a method for testing compatibility with aviation fuel. The method includes providing a certain amount of jet reference fluid (JRF) and evaluating one or more components or systems of an aerospace vehicle (vehicle, aircraft). The method also includes exposing one or more components or systems of the aerospace vehicle to a certain amount of jet reference fluid (JRF) for a period of time. The method also includes evaluating the one or more components or systems of the aerospace vehicle after exposing the one or more components or systems of the aerospace vehicle to the jet reference fluid (JRF). The implementation method of the method for testing compatibility with aviation fuel includes, wherein evaluating the one or more components or systems of the aerospace vehicle may include weighing or visually inspecting the one or more components or systems of the aerospace vehicle. Evaluating the one or more components or systems of the aerospace vehicle after exposing the one or more components or systems of the aerospace vehicle to the jet reference fluid (JRF) may include weighing or visually inspecting the one or more components or systems of the aerospace vehicle. For example, in a long term immersion or exposure test for a sealant or thermoplastic material, the time period can include a period of time from about 1 hour to about 72 hours, or from about 1 hour to about 5,000 hours, or from about 24 hours to about 10,000 hours. One or more components or systems of an aerospace vehicle can include a thermoset, a thermoplastic, a sealant, an elastomer, a metal, a finish, a coating, or a combination thereof. One or more components or systems of an aerospace vehicle can include wiring. One or more components or systems of an aerospace vehicle can include a fuel system. The jet reference fluid (JRF) can include isooctane, n-heptane, toluene, or cyclohexane.

[0011] The features, functions, and advantages that have been discussed can be achieved independently in various implementations or may be combined in yet other implementations, further details of which can be seen with reference to the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present teachings and, together with the description, serve to explain the principles of the present disclosure. In the drawings:

[0013] Figure 1 Exemplary aerospace vehicle applications are described in accordance with the present disclosure.

[0014] It should be noted that some details of the drawings have been simplified and are drawn to facilitate understanding of the teachings of the present invention rather than maintaining strict structural accuracy, detail, and scale. DETAILED DESCRIPTION

[0015] Reference will now be made in detail to exemplary embodiments of the present teachings, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same, similar, or like parts.

[0016] The present disclosure relates to a jet reference fluid (JRF) for sustainable aviation fuel that simulates the chemical properties and behavior of actual sustainable aviation fuel. The chemical composition of sustainable aviation fuel can vary depending on the feedstock and refining methods. The jet reference fluid of the present disclosure can be used to test and evaluate how sustainable aviation fuel interacts with aircraft component materials or systems compared to traditional petroleum-based jet fuel compositions.

[0017] The Sustainable Aviation Fuel (SAF) Jet Reference Fluid (JRF) simulates the boundary conditions of the SAF chemistry that have the most significant impact on a given material. The chemical composition of SAF can vary depending on the feedstock and refining methods. Therefore, JRFs were developed to test how different types of fuels will interact with aircraft materials, such as how 100% synthetic paraffinic kerosene (SPK) may differ from typical petroleum-derived Jet A containing aromatic compounds. For the purposes of this disclosure, boundary conditions for a solvent refer to the following behavior of the solvent during use, contact or exposure to one or more candidate components or test components for use in aerospace applications: where the solvent represents the worst-case scenario that is most likely to degrade or damage one or more candidate components or test components over a period of time. In examples, certain materials may experience increased swelling due to aromatic molecules. In other examples, certain portions of the formulations or ingredients of different materials may be more soluble in one of the aromatic JRFs and the non-aromatic JRFs. Petroleum jet fuels (including SAF) may contain primarily paraffins, which may be normal paraffins, iso-paraffins, cyclo-paraffins, or mixtures thereof, and may or may not contain aromatic compounds. Therefore, it is important to evaluate materials and fuel systems while covering compositional variations of petroleum jet fuels and synthetic jet fuels (including SAF).

[0018] The present disclosure further addresses Jet Reference Fluids (JRFs) developed to have chemistries that represent the boundaries or worst-case scenarios for possible fuel chemistries and their impact on materials in the following general areas: thermosets, thermoplastics, sealants, elastomers, metals, finishes and coatings, wiring. It is also necessary to know the types of materials and fluids that are worst-case scenarios for exposure so that this knowledge can be correlated with the fuel chemistry. The approach can be further evaluated for different types of materials leading to subsequent changes to the Jet Reference Fluid formulation. In an example, Jet A / A-1 may have aromatics in the range of 0-25% by volume. However, it is rare for Jet A to contain low or no aromatics. On the other hand, the most commonly produced synthetic blending components today are hydrogenated esters and fatty acids (HEFAs) with a maximum allowable aromatic content of 0.5% by weight. Of the major components present in jet fuel, the concentration of aromatic compounds has the most significant effect on solubility, surface tension, density, net heat of combustion, and yield sooting index (YSI). Other properties, such as viscosity and freezing point, depend not only on the hydrocarbon species present, but also on the structural isomers within each species.

[0019] The choice of solvent is based on a variety of factors, including the ratio of normal to iso-paraffins typically found in both conventional and sustainable fuels, safety of handling: - for example, while benzene may be the best boundary condition molecule representing aromatics in fuels for material compatibility, there are significant EHS concerns about its use, so toluene is used; - and the range observed in the fuel composition or the range allowed by the specification (e.g., 0-25% aromatics by volume). Therefore, the composition can be further fine-tuned for the application. For example, smaller molecules will have the greatest impact on elastomers and sealants, which can penetrate the material more effectively than larger molecules. Epoxy materials are more susceptible to being affected when water is present, so tests conducted on JRFs used with epoxies can contain water.

[0020] Industrial aviation and its various partners are focused on improving and increasing the utilization of sustainable aviation fuels, up to and including 100% SAF capability by 2030. The disclosed fluid, referred to as Jet Reference Fluid (JRF), can be used to understand how aircraft interact with 100% sustainable aviation fuel (SAF). Where applicable, the definition of a 100% SAF capability target can include 100% synthetic paraffinic kerosene (SPK), which will contain no aromatic components. Furthermore, previously known testing of materials and fuels has not addressed the full spectrum of potential fuel chemistries. Consequently, there may be gaps in the current understanding of material properties in fuels, including current petroleum-derived jet fuels.

[0021] Unlike the fluids described in this disclosure, current jet reference fluids suffer from one or more of the following issues: they may contain significant concentrations of aromatic compounds (thus being very different from 100% SPK), they may be challenging to manufacture and therefore expensive to obtain (i.e., AMS2629 jet reference fuel), and / or they may be inconsistent from batch to batch. Furthermore, existing disclosed jet reference fluids do not significantly affect metallic materials, and it is known to those skilled in the art and from examining the service history of metallic components that corrosion may occur within fuel tanks due to the fuel composition and / or water that may be present within the fuel tanks.

[0022] Figure 1Depicted is an application of an exemplary aerospace vehicle according to the present disclosure. As shown, an aerospace vehicle 100 may include an aircraft or aerospace vehicle. The body 130 of the aircraft or vehicle 100 may include a plurality of individual components or systems, each of which may be exposed to fuel and may need to withstand exposure to these fuels while maintaining optimal performance throughout the service life of the components or systems. The vehicle 100 may also or alternatively include other types of aircraft not shown herein, such as helicopters, unmanned aerial vehicles (UAVs), spacecraft, marine craft, etc. In other implementations, the vehicle 100 may be or include a car, a ship, a train, or the like. In yet other implementations, the systems and methods described below may not be implemented in the vehicle, but may be used to test components or systems included in or contained in the vehicle 100. Aircraft propulsion is typically powered by aviation fuel or conventional jet fuel. Aviation fuel differs from other types of fuel due to the required specific energy or energy per unit mass. For example, the extended energy storage capacity of aviation fuel or kerosene fuel can make long-distance flights possible. There are many types of aviation gasoline, each with unique properties, applications and requirements. These can also be applied to candidate or recently developed sustainable aviation fuels (SAF). In an example, fuel tank materials, such as coatings such as organic coatings or inorganic finishes, sealants, elastomers, such as gaskets or O-rings, wiring, and other components or systems, such as fuel quantity indicating systems (FQIS), which can include one or more of a density meter, a fuel pump, various engine components, a heat exchanger, or a combination thereof. Although illustrative examples are shown in the context of aviation or aerospace vehicles, other systems may also be applicable, such as, but not limited to, ground equipment refueling systems, hydraulic mechanical units (HMUs), or other refueling infrastructure.

[0023] Several exemplary JRF formulations include non-aromatic JRF (N-JRF) consisting of 90% isooctane and 10% n-heptane. Non-aromatic JRF compositions do not contain aromatic compounds. Aromatic compounds can be defined as compounds included in a large class of unsaturated compounds, characterized by one or more planar atomic rings connected by two different types of covalent bonds. The unique stability of these compounds is called aromaticity. Examples of aromatic hydrocarbons or aromatic compounds that can be used in the JRF compositions of the present disclosure include, but are not limited to, heteroaromatic hydrocarbons (compounds in which at least one methylen or vinylene (-C= or -CH=CH-) group is replaced by a heteroatom such as oxygen, nitrogen or sulfur); or benzene-like compounds or benzene derivatives, including exemplary aromatic compounds such as toluene, ethylbenzene, xylene, mesitylene, phenylhexane, biphenyl, phenol, aniline, nitrobenzene, benzoic acid, etc. Therefore, these aromatic compounds can include substituted or unsubstituted aromatic rings. For example, the aromatic ring can be substituted by the following functional groups, such as hydroxyl, alkoxy, halogen, nitro, alkane (such as heptylbenzene), etc., or a combination thereof. One or more of these aforementioned heteroaromatics, heteroatom aromatics, or other substituted aromatic compounds may be present in a relatively small percentage of the total composition, such as 50% or less, and in some instances may be absent. An exemplary high aromatic JRF (HA-JRF) may be composed of 30% toluene, 50% isooctane, 10% cyclohexane, and 10% n-heptane.

[0024] The Jet Reference Fluid (JRF) disclosed herein enables fluid exposure testing using materials that serve as surrogate boundary conditions for candidate SAFs. The uses and methods herein may be included in compatibility testing for one or more components on an aircraft or aerospace vehicle, but also provide a repeatable perspective for system compatibility. Testing the JRF fluid disclosed herein can further understand the boundary conditions of these systems that are in contact with or may be in contact with SAFs. The JRF described herein is a fluid made from simple materials that are controllable and reproducible, providing a means to facilitate data comparison using simple formulations and testing methods using repeatable fluids and methods. In such systems, where aggressive environmental outlooks or plans include the ability to achieve 100% SAFs within a few years, it is critical for any material or system in contact with a candidate SAF to be able to be evaluated for compatibility.

[0025] While the formulation may be known, the JRF of the present disclosure is designed to test to address the extreme compositional boundaries of actual SAFs used in systems or exposed to components. As a standardized method for testing, findings and methods can be shared and compared with similar industry partners. When a SAF is produced, there may be a compositional distribution, however, the JRF represents the isolates of the various molecules in the SAF composition. If a system or component can pass the test method using the JRF, it should be quite obvious that problems that arise when using the actual SAF will be reduced or not obvious. Components of aerospace vehicles can include groups of materials such as sealants, thermoplastics, thermosets, finishes, materials, and related fuel systems and / or components. An additional advantage is that the manufacturer or supplier of a particular SAF is not important because the use and methods of the JRF described herein are not limited to evaluating exposure to any specific fuel.

[0026] Compatibility testing and additional testing methods can help ensure that SAF can be safely used in existing aircraft engines without causing any unforeseen operational issues. Examples of compatibility testing include material compatibility testing, engine performance testing, fuel system testing, storage and handling testing, additive compatibility testing, or cold flow testing, among other tests. Material compatibility testing can include evaluating the compatibility of fuel system materials, such as seals, hoses, gaskets, and other materials exposed to SAF, to understand or ensure that SAF will not degrade or corrode these materials over time. Engine performance testing can assess the impact of SAF on engine performance, including efficiency, thrust, and emissions. Verifying that SAF meets the required combustion specifications in aircraft engines can also be an additional accompanying test. Fuel system testing can examine the behavior of SAF in the fuel system, taking into account factors such as flow characteristics and filtration, as well as ensuring that SAF does not clog or damage fuel system components and is adequately atomized within the combustion chamber. Storage and handling testing plans and examines the effects of long-term storage on SAF properties, providing a preview of handling procedures for SAF and confirming that these handling or storage procedures are similar to those for traditional jet fuel. Cold flow testing can assess the performance of SAFs in colder conditions (such as low temperatures at high altitudes) to avoid problems such as fuel freezing or component precipitation. Additional testing or assessment of responses to JRF exposure can include system responses to fuel composition, such as a fuel quantity indication system (FQIS), which can utilize capacitance or ultrasonic information, where properties such as dielectric constant, density, and bulk modulus are important indicators of performance. Additional physical property tests can be used, such as tensile strength, elongation, modulus, and others for elastomers, adhesion for coatings, or corrosion testing for metals.

[0027] Examples of sustainable aviation fuel (SAF) compositions or manufacturing methods can include hydrotreated esters and fatty acids (HEFA), isoparaffins (SIP) synthesized from hydrotreated fermented sugars, alcohol-to-jet (ATJ), hydrotreated lignocellulosic biomass (HLB), and the like. Illustrative examples of hydrotreated esters and fatty acids (HEFA) include materials derived from vegetable oils or animal fats, which can be chemically similar to traditional jet fuels, wherein the sulfur content is also low. Isoparaffins (SIP) synthesized from hydrotreated fermented sugars can be produced by fermentation of sugars followed by hydrotreatment, and they provide a high energy density similar to traditional aviation fuels. Examples of fuels manufactured by alcohol-to-jet (ATJ) can be derived from alcohols such as ethanol or butanol, which are converted into jet fuels through a series of additional chemical processes. Hydrotreated lignocellulosic biomass (HLB) fuels can be obtained by further hydrotreating lignocellulosic biomass to non-edible plant materials (such as wood, grass, or agricultural residues). Although these are some example pathways for making synthetic blending components or fuels, raw materials, and final compositions, these categories are interrelated to some extent and may overlap. HEFA, SIP, and ATJ are all examples of pathways for making fuels. HLB is a specific category of raw materials that can be utilized through different pathways depending on how it is processed. The fuel composition comprises 100% synthetic paraffinic kerosene (SPK), which can be prepared through HEFA, SIP, and ATJ pathways. However, it should be noted that the composition of SPK can vary based on the raw materials and pathways, including such conditions within a specific pathway, such as temperature, catalyst, catalyst life, and fractionation. Other major categories of synthetic blending components include aromatic compounds, and categories under development include 100% cycloparaffinic fuel (CPK) and 100% synthetic aromatic kerosene (SAK). Although SAK is unlikely to be used as a pure fuel, it can be used as a synthetic blending component. Examples of synthetic blending components are synthetic paraffinic kerosene plus aromatic compounds (ASTM D7566 Appendix 5) and ATJ-SAK (ASTM D7566 Appendix 8). There is also the opportunity to blend these synthetic blending components together to produce fully synthetic "drop-in" fuels that match the experience with petroleum-derived Jet A (eg, blends of HEFA and SAK).

[0028] In an example of a method for testing compatibility with aviation fuel, several steps may be performed, including: providing a quantity of jet reference fluid (JRF); evaluating one or more components or systems of an aerospace vehicle; exposing the one or more components or systems of the aerospace vehicle to the quantity of jet reference fluid (JRF) for a period of time; and evaluating the one or more components or systems of the aerospace vehicle after exposing the one or more components or systems of the aerospace vehicle to the jet reference fluid (JRF). The method for testing compatibility with aviation fuel may include evaluating the one or more components or systems of the aerospace vehicle by weighing or visually inspecting the one or more components or systems of the aerospace vehicle. The method for testing compatibility with aviation fuel may include, after exposing the one or more components or systems of the aerospace vehicle to the jet reference fluid (JRF), evaluating the one or more components or systems of the aerospace vehicle, comprising weighing or visually inspecting the one or more components or systems of the aerospace vehicle. In various examples, the period of time may be a period of time from about 1 hour to about 10,000 hours. In other examples, one or more components or systems of an aerospace vehicle may include thermosets, thermoplastics, sealants, elastomers, metals, finishes, coatings, or combinations thereof. In alternative examples, one or more components or systems of an aerospace vehicle include wiring, which may include one or more conductive metals or insulation or jacketing materials. One or more components or systems of an aerospace vehicle may include a fuel system. The jet reference fluid (JRF) used in this method may include any JRF described within the present disclosure. It should be noted that the fluid exposure parameters (including time and temperature) may vary based on the material, as may the evaluation of the material after fluid exposure. For example, the test exposure conditions may include a time of up to 10,000 hours (which may be referred to as a "long-term soak") and a temperature range of from room temperature (which is considered to be about 25°C) to a temperature of up to about 75°C. For certain materials, part of the test protocol may include "switching loading," in which the sample exposure is switched between high and low aromatic content jet reference fluids over time. It is known from previous testing of nitrile rubber (NBR) O-rings that this can have a different impact on the material's performance than using only a single test fluid. For NBR, jet fuel aromatics can displace the plasticizer within the material. Then, when the test is switched to a fuel without aromatics, the aromatics absorbed into the material disperse into the fuel, and the volume of the O-ring shrinks, which can lead to leakage. A similar effect of extracting discrete components from the material formula may occur during switching loading, and it would be interesting to see if this phenomenon could degrade the material's performance over time.

[0029] One or more jet reference fluid (JRF) compositions of the present disclosure may include a first hydrocarbon and a second hydrocarbon, wherein the first hydrocarbon and the second hydrocarbon do not contain aromatic compounds. For example, the first hydrocarbon may be or contain isooctane. For example, the second hydrocarbon may contain n-heptane. These hydrocarbons may also include cyclohexane, heptane, or any hydrocarbon described herein. Examples of jet reference fluid (JRF) compositions include those in which the first hydrocarbon is present in an amount from about 1% to about 20% by weight, based on the total weight of the jet reference fluid, or those in which the second hydrocarbon is present in an amount from about 50% to about 90% by weight, based on the total weight of the jet reference fluid. The first hydrocarbon fluid or the second hydrocarbon fluid, or any additional fluid added thereto, may be present in an amount from about 1% to about 99% by weight, or from 10% to about 90% by weight, or from 20% to about 80% by weight, or from 30% to about 70% by weight, or from 40% to about 60% by weight, or from 50% to about 75% by weight. In some examples, the JRF composition may further include one or more additives, such as, for example, glycol monomethyl ethers, including ethylene glycol monomethyl ether, 2-(2-methoxyethoxy)ethanol (diethylene glycol monomethyl ether, DiEGME), combinations thereof, and the like. These or other additives may be present in an amount of from about 0.1% to about 10% by weight, or from 1% to about 20% by weight, or from 2% to about 5% by weight, based on the total weight of the JRF. In some examples, the JRF composition includes one or more aromatic compounds, such as toluene, that are included in one of the first hydrocarbon and the second hydrocarbon.

[0030] The examples shown below are compositions of exemplary jet reference fluid mixtures:

[0031] Table 1: Exemplary Non-Aromatic Jet Reference Fluid (N-JRF) Compositions

[0032] Element volume% Isooctane 90±1 n-heptane 10±1

[0033] Table 2: Exemplary Aromatic Jet Reference Fluid Composition with Glycol Monomethyl Ether Additive (JRF-DiEGME)

[0034]

[0035] Table 3: Exemplary Non-Aromatic Jet Reference Composition with Glycol Monomethyl Ether Additive (N-JRF-DiEGME)

[0036]

[0037] Table 4: Exemplary Aromatic Jet Reference Fluid Composition Not Containing Glycol Monomethyl Ether Additive (JRF-LT)

[0038] Ingredient FL1 volume% Toluene 30±0.5 Cyclohexane 10±0.5 Isooctane 50±0.5 n-heptane 10±0.5

[0039] The jet reference fluids listed in the table represent various applicable edge cases for evaluating material compatibility against fuel chemistry. These jet reference fluid formulations are intentionally designed to include readily available materials. Therefore, the use of these fluids should be repeatable and scalable. These materials are compatible with different fuel types. Testing can be simplified and expensive, and variable fluids such as AMS2629 require extensive laboratory testing to produce and are based on Jet A, which may also vary in composition from batch to batch. The shelf life of AMS2629 may be limited, and any extension of the shelf life requires additional testing, which most laboratories cannot easily perform. Using the test fluid compositions disclosed herein, AMS2629 and other such materials are no longer required, thereby saving the testing costs required for various material specification tests. This could have a significant impact on military aircraft, as materials used in aircraft fuel tanks (particularly primers) are proven to be compatible with DiEGME, as DiEGME is a required additive for military fuel specifications. It should be noted that while DiEGME is required for military aircraft, it is also permitted in commercial fuels. If operators determine that DiEGME has advantages (e.g., biostable properties), it may be used more frequently in the commercial fuel sector.

[0040] Additional test fluids used to evaluate metal and inorganic finish exposure may include acid species such as naphthenic acid, naphthoic acid, fatty acids, and sulfur species, as they are known impurities in crude oil, which can be found in finished jet fuel and are known to contribute to metal corrosion. Examples of this are the "synthetic sump" materials shown in Tables 5, 6, and 7 below.

[0041] Table 5: Synthetic oil pan preparation formula

[0042] Salt: Weight fraction <![CDATA[CaCl2]]> 0.0050 <![CDATA[CdCl2]]> 0.1000 <![CDATA[MgCl2]]> 0.0050 NaCl 0.0100 <![CDATA[ZnCl2]]> 0.0010 <![CDATA[CrCl3*6H2O]]> 0.0001 <![CDATA[CuCl3*2H2O]]> 0.0001 <![CDATA[FeCl3]]> 0.0005 <![CDATA[MnCl2*4H2O]]> 0.0005 <![CDATA[NiCl2*6H2O]]> 0.0001 <![CDATA[PbCl2]]> 0.0001 Deionized water (Remaining) 0.8776

[0043] Table 6: Sulfur Species Example Materials

[0044]

[0045] Table 7: Acid species, including example materials of naphthenic acid

[0046]

[0047] Although the present teachings have been described with respect to one or more implementation methods, the examples shown may be changed and / or modified without departing from the spirit and scope of the appended claims. For example, it will be understood that although the process is described as a series of actions or events, the present teachings are not limited by the order of such actions or events. Some actions may occur in a different order and / or simultaneously with other actions or events other than those described herein. Moreover, not all process stages are required to implement the methods according to one or more aspects or embodiments of the present teachings. It will be understood that structural entities and / or processing stages may be added, or existing structural entities and / or processing stages may be removed or modified. Further, one or more actions described herein may be performed in one or more separate actions and / or stages. In addition, the terms "including," "includes," "having," "has," "with," or variations thereof, used in the detailed description and claims, are intended to indicate inclusion in a manner similar to the term "comprising." The term "at least one" is used to indicate that one or more of the listed items may be selected. Further, in the discussion and claims herein, the terms "on," one "on" another, used with respect to two materials, means that there is at least some contact between the materials, while "over" means that the materials are in proximity to each other, but may have one or more additional intermediate materials so that contact is possible but not required. As used herein, neither "on" nor "over" implies any directionality. The term "conformal" describes a coating material in which the angles of the underlying material are maintained by the conformal material. The term "about" indicates that the listed values ​​may vary slightly, as long as the variation does not result in a process or structure that is nonconformant with the illustrated embodiment. The terms "couple," "coupled," "connect," "connection," "connected," "in connection with," and "connecting" mean "directly connected" or "connected via one or more intermediate elements or components." Finally, the terms "exemplary" or "illustrative" indicate that the description is used as an example, rather than implying that it is an ideal. Other embodiments of the present teachings may be apparent to those skilled in the art from consideration of the specification and practice disclosed herein. It is intended that the description and examples be considered exemplary only, with the true scope and spirit of the present teachings being indicated by the following claims.

Claims

1. A jet reference fluid (JRF) composition comprising: a first hydrocarbon; and a second hydrocarbon; and in, The first hydrocarbon and the second hydrocarbon do not contain aromatic compounds.

2. The jet reference fluid (JRF) composition according to claim 1, wherein The first hydrocarbon comprises isooctane.

3. The Jet Reference Fluid (JRF) composition according to claim 1, wherein The second hydrocarbon comprises n-heptane.

4. The Jet Reference Fluid (JRF) composition according to claim 1, wherein The first hydrocarbon is present in an amount of 1% by weight to 20% by weight based on the total weight of the jet reference fluid.

5. The Jet Reference Fluid (JRF) composition according to claim 1, wherein The second hydrocarbon is present in an amount of 50% by weight to 90% by weight based on the total weight of the jet reference fluid. The Jet Reference Fluid (JRF) composition according to claim 1 , further comprising glycol monomethyl ether.

7. The Jet Reference Fluid (JRF) composition according to claim 6, wherein The glycol monomethyl ether is selected from ethylene glycol monomethyl ether, 2-(2-methoxyethoxy)ethanol DiEGME, and combinations thereof.

8. The Jet Reference Fluid (JRF) composition according to claim 6 or 7, wherein The glycol monomethyl ether is present in an amount of 0.1% by weight to 10% by weight based on the total weight of the jet reference fluid.

9. A jet reference fluid (JRF) composition comprising: a first hydrocarbon; and a second hydrocarbon; and in, One of the first hydrocarbon and the second hydrocarbon includes one or more aromatic compounds.

10. The Jet Reference Fluid (JRF) composition according to claim 9, wherein The first hydrocarbon comprises toluene.

11. The Jet Reference Fluid (JRF) composition according to claim 9, wherein The second hydrocarbon comprises isooctane.

12. The Jet Reference Fluid (JRF) composition according to claim 9, further comprising cyclohexane.

13. The Jet Reference Fluid (JRF) composition according to claim 9, further comprising n-heptane.

14. A method for testing compatibility with aviation fuel, comprising: Providing a certain amount of jet reference fluid JRF; evaluating one or more components or systems of an aerospace vehicle (100); exposing the one or more components or systems of the aerospace vehicle (100) to the quantity of jet reference fluid JRF for a period of time; as well as After exposing the one or more components or systems of the aerospace vehicle (100) to the jet reference fluid (JRF), the one or more components or systems of the aerospace vehicle (100) are evaluated.

15. The method for testing compatibility with aviation fuel according to claim 14, wherein: Evaluating the one or more components or systems of the aerospace vehicle (100) includes weighing or visually inspecting the one or more components or systems of the aerospace vehicle (100).

16. The method for testing compatibility with aviation fuel according to claim 14, wherein: After exposing the one or more components or systems of the aerospace vehicle (100) to the jet reference fluid (JRF), evaluating the one or more components or systems of the aerospace vehicle (100) includes weighing or visually inspecting the one or more components or systems of the aerospace vehicle (100).

17. The method for testing compatibility with aviation fuel according to claim 14, wherein: The period of time includes a period of time from 1 hour to 72 hours.

18. The method for testing compatibility with aviation fuel according to claim 14, wherein: The one or more components or systems of the aerospace vehicle (100) include a thermoset material, a thermoplastic material, a sealant, an elastomer, a metal, a veneer, a coating, or a combination thereof.

19. The method for testing compatibility with aviation fuel according to claim 14, wherein: The one or more components or systems of the aerospace vehicle (100) include wiring.

20. The method for testing compatibility with aviation fuel according to claim 14, wherein: The one or more components or systems of the aerospace vehicle (100) include a fuel system.

21. The method for testing compatibility with aviation fuel according to claim 14, wherein: The jet reference fluid JRF contains isooctane and n-heptane.

22. The method for testing compatibility with aviation fuel according to claim 14, wherein: The jet reference fluid JRF comprises toluene and cyclohexane.

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