Abstract:
A simple and compact apparatus, and a method, for determining the characteristics of a number of fluids used in the truck and automotive industries including coolant, bio-diesel, gas-ethanol and diesel engine fluid (DEF). The apparatus includes a sample container providing optical paths of different lengths for making measurements on a sample. The dual path length design allows the apparatus to capture both NIR and UV spectral ranges. The qualitative and quantitative properties of the fluid under test are compared to test results under normal conditions or to the properties of unused fluid. Two light sources are used within a spectrometer with each source being associated with a different optical path length.

Description:
This application claims priority from and the benefit of provisional application Ser. No. 61/666,446 filed on Jun. 29, 2012, the entire contents of which are incorporated herein by reference, for all purposes. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     1. Field of the Disclosure 
     The present disclosure relates to a new apparatus and method for evaluating the condition (i.e. the measurement of properties) of coolant and characteristics and analyses of fuel quality (gasoline-ethanol and bio-diesel) and DEF (diesel engine fluid-urea solution) quality. More particularly, it relates to those apparatus and methods for doing so spectroscopically. 
     2. Background Art 
     Fluid integrity is one of the most important issues in the engine maintenance and condition monitoring. Coolant, fuel, and the urea solutions used in diesel engine fluids are all critical. 
     Coolants 
     Nearly all engines use coolants with similar base fluids: a 50/50 mix of ethylene glycol and water. In some circumstances, industrial engines may utilize other base fluids, such as atomized water or a mixture of propylene glycol and water. In addition to the base fluid, there are a small amount of other ingredients including corrosion inhibitors, antifoam agents, dyes and other additives. While these other ingredients make up only a small fraction of the overall coolant, they are what differentiate one coolant from another. 
     Diverse technologies have been developed to protect engines from corrosion. In Europe, problems with hard water minerals forced coolant technologies to be phosphate-free. Calcium and magnesium, minerals found in hard water, react with phosphate inhibitors to form calcium or magnesium phosphate, which typically leads to scale formation on hot engine surfaces. This could lead to loss of heat transfer or corrosion under the scale. To replace phosphates, conventional European coolants contain a mix of inorganic oxides like silicates and inhibitors called carboxylates. Carboxylates provide corrosion protection by chemically interacting at the metallic corrosion sites, rather than by forming a layer of inhibitors that cover the total surface. The mix of carboxylates and silicates is also called a hybrid technology because it is a mix of conventional inorganic technology and fully carboxylate or organic technology. 
     In Asia, there is a ban on coolants containing silicate. To provide protection, most coolants contain a mix of carboxylates and inorganic inhibitors such as phosphates. 
     These coolants can also be considered hybrids, but they are distinct from the European hybrids due to the lack of silicates. 
     Extended-life carboxylate-based coolants were developed to be globally acceptable and provide superior performance over existing technologies. This technology is also known as organic additive technology (OATs). Because full carboxylate coolants have no silicates, they meet the stringent requirements of the Asian specifications. They also meet the European coolant requirements because they have no phosphates. These coolants have developed international popularity due to having an unsurpassed corrosion protection for extended time intervals. 
     In general, coolants degrade over time as the ethylene glycol breaks down into primarily glycolic and formic acids. Degradation occurs more quickly in engines operating at higher temperatures or those that allow more air into cooling systems. 
     Currently techniques and methods available for routinely detecting and quantifying the quality of coolant is to use test strips. 
     Another test is to check for nitrite and molybdate corrosion inhibitors in the coolant. Most conventional coolants require either continual supplemental coolant additions (SCAs) or lab analysis to ensure proper performance. 
     Various inhibitors, such as nitrites and molybdates, are easily monitored using test strips. Because nitrites deplete rapidly compared to other inhibitors, testing for nitrite allows one to learn the coolant&#39;s nitrite level, but nothing else. Therefore a new testing apparatus and test method was sought out. 
     Some engines require inhibitors such as nitrites to be maintained at certain levels to offer protection against cavitation corrosion, which can occur in engines with removable cylinder liners. Nitrites tend to deplete rapidly in conventional coolants and must be replenished at regular intervals. Carboxylate-based ELC coolants typically have lower nitrite depletion levels because the carboxylates provide the required cavitation protection and therefore much longer preventive maintenance intervals. 
     Some common cause of coolant failure are debris (including rust), leaking heaters, plugged heater (or other restrictions in system), system overheating, electrolysis (unacceptably high voltage in the coolant) which results in degradation of hoses or heater, and improper concentration (mix ratio with water). 
     Bio-Diesel Fuel Quality 
     In comparison to other alternative fuels, there are a number of unique qualities and properties of biodiesel fuel. What makes a fuel different from others are its cetane number and heat of combustion. The viscosity of a fuel is important because it influences the atomization of the fuel being inserted into the engine combustion chamber. Whereas biodiesel fuel property has a viscosity much closer to diesel fuel than vegetable oil, it helps create a much lower drop, which burns cleaner. 
     Another main property of biodiesel fuel is its lubricating properties. It has much better lubricating properties and a higher cetane ratings than today&#39;s lower sulfur diesel fuels. Biodiesel also helps in reducing fuel system wear. The fuel injection equipment depends on the fuel for its lubrication. The biodiesel fuel properties increase the life of the fuel injection equipment. Giving better lubricity, a more complete combustion and an increase in the engine energy output, partially compensates for the lower energy density of biodiesel fuel as compared to petrodiesel. 
     The physical properties of biodiesel fuel include, the possibility of being different in color, from golden and dark brown, all depending on the production feedstock. It is immiscible with water, has a high boiling point and low vapor pressure. The flash point of biodiesel is considerably higher than that of petroleum diesel. Biodiesel fuel has a density of ˜0.88 g/cm 3 , which is less than that of water. It has practically no sulfur content, and is frequently used as an additive to Ultra-Low Sulfur Diesel (ULSD) fuel. Biodiesel fuel has an effect on copper-based materials, and as well on zinc, tin, lead, and cast iron. However, the stainless steels and aluminum are not affected by bio fuel. Biodiesel fuel properties also have an effect on some types of natural rubbers found in some older engine components. However, the frequently used synthetic rubbers FKM-GBL-S and FKM-GF-S found in current vehicles are found to handle biodiesel under virtually all conditions. 
     Gas-Ethanol Quality 
     When fuel contains more than 10 percent ethanol, problems can arise in a vehicle, including engine stalling, failed starting and difficulty accelerating. It can also decrease the life of the engine. Because fuel station owners are not required to test the levels of ethanol in the fuel delivered, and car owners do not become aware of the problem until damage has been done, it is important to test the levels of ethanol in the fuel being used. 
     Using the characteristic spectral components of materials, the new apparatus for multifunctional fluid meter and method for measuring coolant, bio-diesel, gas-ethanol and diesel engine fluid (DEF) will be able to measure and report the following gas-ethanol properties; specifically the percentage of ethanol in gasoline. 
     DEF (Diesel Exhaust Fluid) Quality 
     DEF is a high purity solution of 32.5% urea in deionized water. Urea is a colorless, odorless, non-hazardous, non-flammable, non-combustible crystalline solid made from natural gas, with a molecular weight of 60 and molecular formula of (NH 2 ) 2 CO. 
     DEF is used to convert noxious NOx into harmless nitrogen gas. 
     In 2000 and 2001, the EPA mandated tougher emission control standards to be phased in for all on-highway vehicles. Effective Jan. 1, 2010, all new on-road vehicles sold must meet the emission standard of 0.2 grams of nitrogen oxide (NOx) per brake horsepower-hour. Vehicle and engine manufacturers have developed Selective Catalytic Reduction (SCR) technology, which uses DEF to convert noxious NOx into harmless nitrogen gas, which makes up 80% of the air we breathe. Industry projections on SCR acceptance vary: 90% of heavy duty trucks, beginning in 2010, are expected to use SCR, while 50-75% of diesel cars and light duty vehicles are expected to use SCR technology. Auto and truck makers have invested significant time and resources to develop the technology and have developed a set of internationally accepted standards—ISO22241—for the production and use of DEF. If these standards are not met, there is a serious risk of poisoning the catalyst used in the vehicle mounted SCR system. 
     Most cars and light duty trucks will have 5-7 gallon on-vehicle tanks to store DEF, while heavy duty trucks will have 10-30 gallon tanks. This DEF is metered by the on-board computer into the exhaust gas at rates required to meet the tailpipe NOx standards. 
     Based on the following assumptions for the light duty market—7-gallon DEF tank, 20 miles per gallon of diesel, 2-4 gallons of DEF per 100 gallons of diesel—a car or pickup truck owner will likely need to fill the DEF tank every 3,500-7,000 miles, or about the interval between oil changes. So, it is likely that most car and light duty owners will have the DEF tank topped off during oil change services. 
     For heavy duty vehicles—18 gallon DEF tank, 6 miles per gallon of diesel, 2-4 gallons of DEF per 100 gallons of diesel—a truck owner will likely need to fill the DEF tank every 2,700-5,400 miles, which is much more frequent than for cars and light duty trucks. So, it&#39;s likely that most heavy duty trucks will top off DEF tanks during every second or third fuel fills. 
     In view of all of the above requirements, a device for on-site measurement of fluid characteristic integrity is desired. Further, such a device should be compact, cost effective, easy to operate and provide reliable results. 
     SUMMARY OF THE DISCLOSURE 
     It is an object of this disclosure to provide a simple and compact apparatus for determining the characteristics of a number of fluids used in the truck and automotive industries. 
     It is a further object of the disclosure to provide a sample container providing optical paths of different lengths for making measurements on a sample. 
     It is another object of the disclosure to provide a dual path length spectrometer for making measurements in the visual (VIS) range of 200 nm-750 nm and the near infared (NIR) range of 750 nm-1100 nm. 
     Using the characteristic spectral components of materials, the disclosure is directed to an apparatus useable as a multifunctional fluid meter and to a method for measuring coolant, bio-diesel, gas-ethanol and diesel engine fluid (DEF), and to measure and report on the following properties: 
     A. For coolants: nitrite, the boiling point, and the freezing point. 
     B. Percent biodiesel in diesel fuel. 
     C. Percent DEF and percent urea in diesel engine fluid (DEF). 
     D. For gasoline containing ethanol, the percentage of ethanol. 
     The apparatus tests for qualitative and quantitative properties of the fluid under test by comparing test results to normal conditions. The apparatus then can determine the physical properties of the fluid being analyzed. The apparatus is an instrument that integrates two light sources within a spectrometer, each source being associated with a different optical path length. This dual path length design allows the apparatus to capture both NIR and UV spectral (300 nm-1100 nm) ranges. 
     An onboard computer controls the spectrometer and tabulates the results based on the data gathered. Software generates a report that includes the test results and a grading code. The code is a summary of the test results and gives an indication of the fluid properties. 
     The instrument features a broad-band optical spectrometer coupled to a custom sample compartment, a dedicated dual light source and an embedded data processing unit. 
     In accordance with the disclosure, an apparatus for analyzing a plurality of fluids, comprises a portion with an opening for receiving a fluid sample holder, the fluid sample holder having a fluid receiving portion of rectangular cross-section to define a first path for radiation of first wavelengths through fluid in the fluid receiving portion, and a second path for radiation of second wavelengths through fluid in the fluid receiving portion, the first path being shorter than the second path; a first source of radiation of the first wavelengths; a second source for radiation of the second wavelengths; a spectrometer for receiving the radiation of first wavelengths and the radiation of the second wavelengths after the radiation of the first wavelengths and the radiation of the second wavelengths have passed through the fluid and the fluid sample holder. The first wavelengths are shorter than the second wavelengths. The first wavelengths can be in a range of 200 nm to 750 nm and the second wavelengths can be in a range of 750 nm to 1100 nm. 
     The apparatus can further comprise a first set of optical elements for receiving and guiding the radiation of the first wavelengths to the spectrometer; and a second set of optical elements for receiving and guiding the radiation of the second wavelengths to the spectrometer. 
     The first source can be a deuterium lamp and the second source can be an incandescent tungsten lamp. 
     The apparatus can further comprisea database of properties of fluids to be analyzed by the apparatus, the properties being of the fluids in an unused state; and a processor for receiving an output of the spectrometer, processing the output to determine properties of the fluid being analyzed, and comparing the properties of the fluid being analyzed to properties of a corresponding fluid in an unused state, in the database. The processor can generate at least one diagnostic code based on the comparing of the properties of the fluid being analyzed to properties of a corresponding fluid in an unused state. 
     A memory can store a set of models, wherein the models provide rules for analyzing the fluids being analyzed. 
     In accordance with the disclosure, a method for analyzing a plurality of fluids, comprises: propagating along a first path, radiation of first wavelengths through a fluid, propagating along a second path radiation of second wavelengths through the fluid, the first path being shorter than the second path; receiving with a spectrometer the radiation of first wavelengths and the radiation of the second wavelengths after the radiation of the first wavelengths and the radiation of the second wavelengths propagates through the fluid; and analyzing the radiation of first wavelengths and the radiation of the second wavelengths to determine characteristics of the fluid. 
     The first wavelengths are shorter than the second wavelengths. The first wavelengths can be in a range of 200 nm to 750 nm and the second wavelengths can be in a range of 750 nm to 1100 nm. 
     The radiation of first wavelengths is a provided can be from a deuterium lamp and the second radiation of second wavelengths can be from an incandescent tungsten lamp. 
     The method further comprises processing an output of the spectrometer to determine properties of the fluid being analyzed; and comparing the properties of the fluid being analyzed to properties of a corresponding fluid in an unused state. 
     At least one diagnostic code based is generated by comparing of the properties of the fluid being analyzed to properties of a corresponding fluid in an unused state. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and other features of the present disclosure are explained in the following description, taken in connection with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of an embodiment of an apparatus for analyzing a fluid sample in accordance with the present disclosure. 
         FIG. 2  is an embodiment of a dual path sample container for use in the apparatus of  FIG. 1 . 
         FIG. 3  is a simplified schematic and functional block diagram of the apparatus of  FIG. 1 . 
         FIG. 4  is a high level system flow chart of the operation of the embodiment of  FIG. 1 . 
         FIG. 5  is a logical illustration of the types of fluids that can be analyzed with the exemplary embodiment of  FIG. 1 . 
         FIG. 6  is a flow chart of a series of steps that are performed for coolant analysis. 
         FIG. 7  is an example of a series of steps that are performed for bio-diesel fuel quality analysis. 
         FIG. 8  is an example of a series of steps that are performed for Gas-ethanol fuel quality analysis. 
         FIG. 9  is an example of a series of steps that performed for diesel exhaust fluid quality analysis. 
         FIG. 10  illustrates a series of recommendations for a report on coolant propertied. 
         FIG. 11  is an example of a report, with explanatory notations, generated by the embodiment of the apparatus illustrated in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , there is shown a perspective view of an apparatus incorporating features of the present disclosure. Although the apparatus will be described with reference to the embodiment shown in the drawings, it should be understood that the present disclosure can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used. 
     The instrument enclosure  20  is a molded plastic case that includes a user interface touch screen display  22 , an opening  24  for receiving a sample container  26  ( FIG. 2 ) with a container cover  28 , and a sample chamber cover  30 , which is hinged to enclosure  20  with hinge assembly  32 . In use, sample chamber cover  30  is positioned directly over container cover  28  so that the sample container  26  is held in place, and stray light does not enter container  26 . 
     Instrument enclosure  20  includes a first portion  34 , which is substantially rectangular, with a curved front wall  35 , in which largely the optical components of the apparatus are housed. A second portion  36  includes a sloping surface  40 , having a window or opening therein for exposing the touch screen display  22 . A bottom cover  42  is secured, preferably removeably, to a top portion  44  of enclosure  20 . Second portion  36  houses largely the electronic components of the apparatus. 
     Referring to  FIG. 2 , a sample container  26 , formed of a clear polymer, such as PMMA, or a clear optical grade acrylic is designed to be accepted within opening  24  ( FIG. 1 ), includes a substantially rectangular sample cell region  48 , and a substantially cylindrical top portion  50 . Top portion  50  is configured with an external thread  52  for mating with an internal thread (not shown) of container cover  28 , when container cover  28  is screwed on to sample container  26 . Sample cell region  48  is configured with two parallel rectangular protrusions  54 A and  54 B on one of its larger surfaces, and with two parallel rectangular protrusions  56 A and  56 B on the other of its larger surfaces. The position of these rectangular protrusions is such that sample container  26  may be rotated by 180 degrees, and still be accepted within opening  24 . The rectangular shape of sample cell region  48  provides two perpendicular paths of different lengths, both paths being perpendicular to the longitudinal axis of top portion  50 , for the passage of light of different wavelengths therethrough, as more fully described below with respect to  FIG. 3 . 
       FIG. 3  is a simplified schematic and functional block diagram of the apparatus within enclosure  20 . The optical instrumentation  60  includes a dual spectrometer  62  configured with a broad-range diffraction grating (not shown), covering the range from 200 nm to 1100 nm. A first light source  64 , which is preferably a deuterium source, provides illumination along a first sample path length of dimension X, which is the shorter path through the sample container  26 . Light traveling through the sample container walls and the sample contained therein, generally in the wavelength range of 200 nm to 750 nm, arrives at a set of optics  66 , which collects light, that is guided by a fiber optic cable  66 A to detector  62 . A second light source  67 , which is preferably a tungsten light source, provides illumination along a second sample path length of dimension Y, which is the longer path through the sample container  26 . Light traveling through the sample container walls and the sample contained therein, generally in the wavelength range of 750 nm to 1100 nm, illuminates a second set of optics  68 , which collects light, that is guided by a fiber optic cable  68 A to detector  62 . 
     A computer module  70 , which is preferably a dedicated industrial grade tablet PC with an embedded operating system, has associated therewith a touch-screen user display interface  72 , a printer output  74  and external communications interface  76 , for USB and Ethernet connections. Computer module  70  may include analog and digital processor or processors, and a database, used as described below. Preferably, the system is powered by a dedicated software package based on a touch screen/push button user interface. The system is based on a database driven operating environment. The output/results are delivered to the screen by display interface  72 , and can be sent through the USB interface to an external printer. The fundamental properties of the used fluid to be analyzed is estimated from recorded spectral data from new (unused) and used fluid samples. The primary calculations for coolant fluid include the ethylene glycol content (and associated properties—freezing and boiling points), basic composition (coolant type—differentiating ELC blends), and certain inhibitors, as more fully described below. 
     A power adapter  78  having a 115/230 volt AC input  80  provides the various DC voltages required by a distributed circuit board  82 , the dual spectrometer  62 , light sources  64  and  67 , and computer  70 . 
       FIG. 4  is a high level flow chart of the operation of an embodiment of an apparatus in accordance with the disclosure. At  86 , the user defines parameters of the sample to be measured. A data integrity check is conducted at  88 . At  90 , rules associated with the sample parameter(s) inputted are evaluated. All the main calculations for glycol, DEF, fuels, etc. are carried out by multiple linear regression (MLR) or partial least squares (PLS) models. At  92 , basic diagnostic codes are generated based on model rules. At  94 , the diagnostic codes are expanded into descriptive text for display to a user. At  96 , the test results may be outputted and a report printed on an attached printer. 
       FIG. 5  illustrates the basic multiple functionality, starting at a general display  98 . The user is able to select the fluid to be analyzed as coolant  100 , bio-diesel fuel  120 , gas-ethanol mixtures  140  and DEF  160 . After the selection is made, the flow charts of  FIGS. 6, 7, 8 and 9 , respectively, for the possible selections  100 ,  120 ,  140  and  160  are followed. 
     The flowcharts of  FIGS. 7, 8 and 9  are identical. However, the flowchart of  FIG. 6  is described first, because it is different from those of  FIGS. 7, 8 and 9  in the analysis conducted in the last step  110 . Otherwise, the description relating to  FIG. 6  below is identical to that for  FIGS. 7, 8 and 9 , wherein like last digits indicate identical steps. 
     A software model is used to calculate the concentrations of glycol, DEF, gas-ethanol, or biodiesel. Three different approaches or models, such as for example, those mentioned below, can be used for different ranges of wavelength within the overall spectrum. Then a polynomial (2nd or 3rd order) fit is applied to obtain what is considered to be the best overall fit for the spectrum. The coefficients are stored and used to do the final calculation on a specific instrument. 
     In the case of sample matching for type and color, a simple goodness of fit calculation, based on a vector calculation, is used. 
     For coolants, nitrite concentration is calculated from a highly overlapped absorption and the nitrite contribution is estimated by separating the absorption by means of a Saviitzky-Golay second derivative. The final value is computed from the span (Max-Min) of the derivative signature. A simple Beer&#39;s law computation is used for calculating the final result. A similar computation is used for the exclusion of the non-nitrite component. 
     In  FIG. 6 , when coolant is selected, regulation of wavelength provided by the sources occurs at  102 . At  104 , at predetermined, application driven intervals, a background calibration spectrum is established using an empty sample container ( FIG. 2 ) in opening  24 , as prompted by software. A background spectrum that was stored during the initial set-up of the instrument, is applied to this spectrum, and interpreted by the software to be the proper settings. 
     At  106 , features in the background spectrum having known wavelengths are selected. At  108 , a measured value of a selected background spectral feature of the sample fluid is determined. A sample container  26  is introduced into the opening  24 . A UV-VIS light source is then turned on and the spectrum is acquired using the path-length setting based on the width of the sample container  26 . This source is turned off and a second NIR light source is turned on and the second spectrum is added to the first using a longer path-length based on the width of the sample container  26 . At  110 , wavelength values of the sample spectrum are translated in accordance with the known wavelength values, the measured wavelength values, and a predetermined translation strategy. In this regard, reference is made to U.S. Pat. No. 6,707,043, wherein, as an example only, a method of regularizing a sample spectrum of a fluid sample is disclosed. The spectrum is then modeled against a large database set of known values to help determine certain results; other results are calculated by measuring certain areas of the spectral range and applying specific algorithms. 
     In steps  130 ,  150  and  170  of  FIGS. 7, 8 and 9 , respectively, it is only necessary to translate the sample spectrum in accordance with the measured wavelength values. 
       FIG. 10  includes report recommendation for various situations which may arise during an evaluation of a coolant sample. The recommendations are believed to be self-explanatory. 
       FIG. 11  shows a typical report  200 , and includes explanatory material for the items in the report. A report of this type can be shown on touch screen display  22 . Again, this is believed to be self-explanatory. 
     It should be understood that the foregoing description is only illustrative of the disclosure. Various alternatives and modifications can be devised by those skilled in the art. Accordingly, the present disclosure is intended to embrace all such alternatives, modifications and variances.