Quantitative Evaluation of the Emissions of a Transport Engine Operating with Diesel-Biodiesel

energies

Article Quantitative Evaluation of the Emissions of a Transport Engine Operating with Diesel-Biodiesel

Armando Pérez 1,* , David Mateos 2 , Conrado García 2 , Camilo Caraveo 1 , Gisela Montero 2 , Marcos Coronado 2 and Benjamín Valdez 2 1 Facultad de Ciencias de la Ingeniería y Tecnología, Universidad Autónoma de Baja California, Blvd. Universitario #1000, Unidad Valle de las Palmas, Baja California CP. 21500, Mexico; [email protected] 2 Instituto de Ingeniería, Universidad Autónoma de Baja California, Blvd. Benito Juárez y Calle de la Normal S/N, Col. Insurgentes Este, Mexicali, Baja California 21280, Mexico; [email protected] (D.M.); [email protected] (C.G.); [email protected] (G.M.); [email protected] (M.C.); [email protected] (B.V.) * Correspondence: [email protected]

Received: 22 May 2020; Accepted: 2 July 2020; Published: 13 July 2020

Abstract: The present work is about evaluating the emission characteristics of biodiesel-diesel blends in a reciprocating engine. The biodiesel was produced and characterized before the test. A virtual instrument was developed to evaluate the velocity, fuel consumption, temperature, and emissions of O2, CO, SO2, and NO from an ignition-compression engine of four cylinders with a constant rate of 850 rpm. The percentages of soybean-biodiesel (B) blended with Mexican-diesel (D) analyzed were 2% B-98% D (B2), 5% B-95% B (B5), and 20% B-80% D (B20). The biodiesel was obtained through a transesteriﬁcation process and was characterized using Fourier-Transform Infrared spectroscopy and Raman spectroscopy. Our results indicate that CO emission is 6%, 10%, and 18% lower for B2, B5, and B20, respectively, in comparison with 100% (D100). The O2 emission is 12% greater in B20 than D100. A reduction of 3% NO and 2.6% SO2 was found in comparison to D100. The obtained results show 44.9 kJ/g of diesel’s lower heating value, this result which is 13% less than the biodiesel value, 2.8% less than B20, 1.3% than B5, and practically the same as B2. The speciﬁc viscosity stands out with 0.024 Poise for the B100 at 73 ◦C, which is 63% greater than D100. The infrared spectra show characteristics signals of esters groups (C-O) and the pronounced peak from the carbonyl group (C=O). It is observed that the increase in absorbance of the carbonyl group corresponds to an increase in biodiesel concentration.

Keywords: virtual instrument; LabVIEW; characterization; diesel-biodiesel; emissions; infrared spectra

1. Introduction In recent decades, many studies on biofuels have been conducted to reduce air pollution generated primarily by internal combustion engines (ICEs). The ICE is used in diﬀerent means of transport as well as in other internal combustion equipment. As above, the dependence on fossil fuels has increased without neglecting the decrease in the production of petroleum-based energetics [1–3]. It is important to take into account that the increase in fossil fuels consumption also produces an increase in environmental problems. Considering the Statistical Review of World Energy issued by the British Petroleum Statistical Review (BP), it was mentioned that in 2016, the global consumption of primary energy increased 1% with respect to the 0.9% of 2015, and in turn, the production and consumption of all the fuels increased except the production of nuclear energy [4]. The worldwide production of biodiesel was 25 billion L in 2013, and in 2015 it increased to 129 billion L approximately. It represents an increment of 5.1% [5,6].

Energies 2020, 13, 3594; doi:10.3390/en13143594 www.mdpi.com/journal/energies Energies 2020, 13, 3594 2 of 14

There are many studies concerning the use of biodiesel as a substitute for diesel, but this proposal was not recent. From the invention of the compression ignition engine (CIE), Rudolf Diesel proposed the use of 100% peanut oil as fuel for the engine operation. Later, many subsequent studies have shown that vegetable oils used to produce biodiesel can be renewable. The studies reveal that it is easy to produce and has a high calorific value. Other research works have been developed to improve biodiesel characteristics like the poor flow and low volatility at low temperatures [7–9]. Biodiesel is considered an alternative biofuel to diesel, because it can be produced with oils that come from vegetables or animal fat, making it biodegradable and renewable. The CIE’s emissions coming from the combustion contains up to 10% oxygen in its structure, this promotes better combustion because it turns oxygen into a more oxygenated fuel that favors a complete and efficient combustible, reducing the non-burned hydrocarbon production and suspended particles. The environmental impact in CO2 terms is strongly affected by the absorption of this gas by plants during its growth [10–13]. Another main biodiesel advantage is that it does not contain carcinogens as polychromatic and polyaromatic nitrided hydrocarbons (PNHs), producing less harmful health contamination when it is burned inside the combustion chamber [14–16]. There are different tools to measure the CIE’s emissions, some equipment is portable or stationary. This equipment normally has a high price and does not have the option to modify the measurement range, which makes them a rigid tool, and they are limited to specific applications without having the versatility and flexibility to adapt them to other required uses [17,18]. Virtual instrumentation (VI) establishes a technology based on the use of software systems, hardware, and a computer. It replaces a measurement and control system in the real world, any program and hardware that fulfills this function [19,20]. In almost all commercial systems, the concept of VI is realized in an object-oriented programming language, modern scientific instrumentation, development, and evolution of VI-based systems [21,22]. The main advantages are (i) versatility and performance of the software and hardware; (ii) the reduced cost for acquisition of a sensor channel, in comparison to traditional rigid hardware systems; (iii) combination of the non-exclusive operating hardware with powerful software that results in a scalable architecture instrument, which means the possibility of being modified if necessary [23]. Therefore, the implementation of VI for measuring CIE’s emissions is feasible, due to the need to monitor the implementation of biodiesel and verify its impact compared to diesel. There are many studies, which prove the reduction of emissions by the use of biofuels. It has to be expected that the implementation of the use of biodiesel reduces the CO2 emissions by using a mixture of diesel-biodiesel as fuel in substitute of diesel [24,25]. However, some research groups report that NOx emission does not change and sometimes an increase occurs [26–29]. It is reported that the biodiesel has a lower calorific value than diesel, this has a direct repercussion on the power generated by the CIE, derived from a higher consumption to counteract the power demanded by the user [30,31]. Some of the models of vehicles with more recent diesel engines have the characteristic to endure mixtures of diesel-biodiesel until 20% of the second one (B20), offering the advantages of biofuel implementation without affecting the engine efficiency. The aim of this work is to assess the technical operation of a CIE using the following mixtures: B2 (98% biodiesel–2% diesel), B5 (95% biodiesel–5% diesel), B20 (80% biodiesel–20% diesel), B100 (100% biodiesel), and D100 (100% diesel). The biodiesel was obtained through a transesterification process from soy oil. Raman and Fourier-transform infrared (FTIR) spectroscopy were used to analyze the mixtures. Additionally, physicochemical properties of mixtures, such as calorific value and viscosity were determined. Another novelty is the development of a virtual instrument using the LabVIEW program for emissions monitoring. Currently, the emissions measurement is performed by gas analyzers based on electrochemical and infrared techniques. Hence, the program, in the form of an interactive graphical user interface, is an additional innovation. The developed VI assesses the specific fuel consumption, temperature from the exhaust gas, engine temperature, and the emission of the exhaust gases: O2, CO, Energies 2020, 13, 3594 3 of 14

SO2, and NO. The basic parameters of Mercedes-Benz 9004 engine are shown in Table1, this type of engine is commonly used in urban transportation trucks in Mexicali, Mexico.

Table 1. Parameters of Mercedes-Benz 9004 engine.

Parameter Value Unit Number of cylinders In-line four cylinders - Cylinder diameter 102 mm Stroke 130 mm Displacement volume 4.25 lt Compression ratio 17.4:1 - Rated power at 2300 rpm 141.7 kW Maximum torque at 1200–1600 rpm 705.02 Nm Intake valve 2 - Exhaust valve 1 - Decompression valve 1 - Redline 2300 - Injection Direct injection -

2. Materials and Methods

2.1. Virtual Instrument for Measuring Engine Parameters The virtual instrument developed to measure engine parameters (VIMEP) is composed of four systems. The ﬁrst comprises temperature sensors, revolutions per minute, fuel consumption, and O2, NO, CO, SO2 gas content. A Faraday cage was used to isolate electromagnetic noise, which could cause interference and alterations in the sensors used for emission readings. The second system consists of conditioners and signal ampliﬁers for each sensor. In third place, the Data Acquisitions Systems (DAQ) board and the PC with the virtual instrument. Finally, the fourth system is the acquisition and data processing DAQ board 6009 USB model, with eight analogic input of 14 bits, 48 kS/s, and two static analogic output of 12 bits, 12 digital input-output, and a 32-bit counter by National Instruments. The digital signals are transferred to the Lenovo Intel ® Core ™ i7-471CHQ CPU at 2.50 GHz with Windows 10 operating system. Table2 shows the properties and operating ranges of each sensor used to detect each type of emission. The sensors have an infrared and electrochemical response [22].

Table 2. Properties and operation range of sensors.

Ranges Sensor Properties O2 CO SO2 NO Concentration ranges (ppm) 0–30 0–500 0–2000 0–2000 Sensitivity (ppm) N/A 55–85 8–20 320–480 Maximum overload 100% 1500 ppm N/A 1000 ppm Resolution 0.1% 1 ppm 5 ppm 0 to 4.5 ppm Response time (s) 15–90 30–90 60–90 35–90 Temperature range ( C) 20 to +55 20 to +50 20 to +50 20 to +50 ◦ − − − − Relative humidity (%) 15–95 15–90 15–90 15–90 Pressure range (kPa) 90–110 90–110 90–110 90–110

In Figure1, we can observe the block programming diagram that constitutes the VIMEP used for the characterization of the CIE when works with diesel-biodiesel mixtures. Energies 2020, 13, 3594 4 of 14 Energies 2020, 13, x FOR PEER REVIEW 4 of 15

FigureFigure 1. 1.The The programming programming of of main main blocks blocks of ofVIMEP. VIMEP.

2.2. Fuel2.2. Fuel and and Its MixturesIts Mixtures Elaboration Elaboration SoybeanSoybean oil wasoil was used used to obtainto obtain biodiesel. biodiesel. Furthermore, Furthermore, toto removeremove the moisture moisture present present in in the the oil, oil, the oil was preheated to 110 °C. The transesterification method was implemented, in which the oil was preheated to 110 ◦C. The transesterification method was implemented, in which sodium sodium methoxide and soybean oil were treaties. The chemical reaction was carried out for 1 h at 60 methoxide and soybean oil were treaties. The chemical reaction was carried out for 1 h at 60 ◦C with °C with agitation. A funnel was used to separate the glycerin and biodiesel by density difference, a agitation. A funnel was used to separate the glycerin and biodiesel by density difference, a volumetric volumetric ratio of 4:1 was used to wash the biodiesel with water. The final step consisted of heating ratio of 4:1 was used to wash the biodiesel with water. The final step consisted of heating the biodiesel the biodiesel to 110 °C, to evaporate the biodiesel water from the biodiesel [32–35]. The biodiesel was to 110prepared◦C, to evaporate in the Institute the biodiesel of Engineering water fromof the the Au biodieseltonomous [ 32University–35]. The of biodiesel Baja California was prepared (UABC). in the InstituteThe fuel of Engineering mixtures were of characterized the Autonomous using Universitya CAP 2000+ of viscometer Baja California and to determine (UABC). Thethe kinematic fuel mixtures wereviscosity characterized of Mexican using diesel a CAP a value 2000 +betweenviscometer 1.9 and and 4.1 tomm determine2/s was used the from kinematic PEMEX viscosity data sheet of [36]. Mexican dieselThe a valuecalorific between value 1.9was and determined 4.1 mm2 /usings was an used IKA from C2000 PEMEX calorimeter. data sheet For [36the]. measurements, The calorific value was determinedapproximately using 0.5 g an were IKA placed C2000 inside calorimeter. the equipment For the and measurements, duplicate tests approximately were performed 0.5 to g were placeddetermine inside thethe equipmentaverage value and of duplicateheat released tests by werecombustion performed of the tofuel determine mixture. Additionally, the average valuethe of heat releasedoptical characterization by combustion of ofthe the fuels fuel was mixture. carried out Additionally, to obtain their the characteristic optical characterization spectra. For Raman of the fuels spectroscopy, a Perkin-Elmer Raman Station 400F with a 785 nm laser at room temperature was used. was carried out to obtain their characteristic spectra. For Raman spectroscopy, a Perkin-Elmer Raman Additionally, FTIR spectra were measured by Perkin Elmer Spectrum One FTIR spectrometer in the Station 400F with a 785 nm laser at room temperature was used. Additionally, FTIR spectra were range of 400–4000 cm−1 and 4 cm−1 resolutions. The uncertainties of the engine performance and 1 1 measuredcalibration by Perkin of the Elmermeasuring Spectrum instruments, One FTIR as well spectrometer as environmental in the conditions, range of 400–4000 were then cm determined− and 4 cm− resolutions.for the measured The uncertainties and calculated of the values. engine The performance percentage anduncertainties calibration of th ofe themeasuring measuring instruments instruments, as wellused as in environmental this study are tabulated conditions, in Table were 3. then Each determined parameter was for measured the measured three times and calculatedto reduce the values. The percentageuncertainties uncertainties of the observed of thevalues measuring and the instrumentsaverage value used was inthen this determined. study are tabulatedThe percentage in Table 3. Eachuncertainty parameter of was the measuredengine performance three times and to exhaust reduce emission the uncertainties parameters ofmeasured the observed in this valuesstudy was and the averagefound value to be was around then 1%, determined. which is deemed The percentage satisfactory. uncertainty of the engine performance and exhaust emission parameters measured in this study was found to be around 1%, which is deemed satisfactory.

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Table 3. Percentage uncertainty of the measuring instruments. Energies 2020, 13, 3594 5 of 14 Percentage Measured Parameter Measurement Range Accuracy Measurement Sensor Uncertainty Table 3. Percentage uncertainty of the measuring instruments. (%) Engine speed (rpm) 0–10,000 ±1 Magnetic pickup speed transducer ±0.1 Measurement Percentage TimeMeasured (s) Parameter - Accuracy ±0.1 Measurement Sensor - ±0.2 Fuel flow (mL/min) 20–6000Range ±10 Flow Sensor Meter Uncertainty (%) ±2 Magnetic pickup speed ViscometerEngine (Poise) speed (rpm) 0.2–15,000 0–10,000 Poise <1 1mL Speed of Rotation 5–1000 RPM 0.1 ±0.5 Calorimeter (J) 0–40,000 ± ±1 Temperaturetransducer sensor ± ±0.2 Time (s) - 0.1 - 0.2 4± cm−1 ± Fuel ﬂow (mL/min) 20–6000 10 Flow Sensor Meter 2 ± ± Viscometer (Poise) 0.2–15,000 Poise FWHM<1 mL Pear Speed of Rotation 5–1000 RPM 0.5 High sensitivity open electrode CCD± Calorimeter (J)95–3500 0–40,000 cm−1 Raman resolution1 Temperature sensor 0.2 RAMAN spectroscopy 1± detector, 1024 × 256 pixels sensor ± shift 4 cmand− FWHM1cm−1 High sensitivity open electrode 95–3500 cm 1 Pear resolution and CCDhermetically detector, 1024 sealed256 pixels vacuum RAMAN spectroscopy − Pixel × Raman shift 1 cm 1 Pixel sensor hermetically sealed resolution− resolution vacuum Fourier-TransformFourier-Transform 785 nm785 laser nm laserat room at room temperature was 350–7800350–7800 cm −11 0.5 0.5 to to 64 64 cm cm1−1 InfraredInfrared spectroscopy spectroscopy − − temperature wasused used

2.3. Operation Conditions of CI-Engine The engineengine worksworks withwith B2, B2, B5, B5, and and B20 B20 mixtures mixtures and and D100. D100. Three Three repetitions repetitions were were carried carried out out for eachfor each mixture mixture under under the following the following conditions: conditions: controlled controlled ambient ambient temperature temperature 23 ◦C with 23 a°C variation with a ofvariation+/ 1 C,of +/ the− 1 air °C, supply the air supply to the engineto the engine of 1 atm of 1of atm pressure, of pressure, a relative a relative humidity humidity of 40%of 40% with with a − ◦ variationa variation of of+/ +/5%,− 5%, and and 2 L 2 of L fuelof fuel as initial as initial volume. volume. When When a fuel a changefuel change is made, is made, the fuel the tank, fuel lines,tank, − fuellines, filters, fuel filters, priming priming pump, pump, high-pressure high-pressure pump pump are purged are purged and and finally, finally, the enginethe engine is turned is turned up forup 20formin, 20 min, to ensureto ensure that that no no residue residue of of the the previous previous mixture mixture remains remains inside inside the the system. system. TheThe physicalphysical measurement systemsystem ofof emissionsemissions hashas aa heat exchanger. To guaranteeguarantee thethe rightright function ofof the sensors thethe temperaturetemperature ofof thethe gasesgases waswas setset atat 50 ◦°C,C, also three general humidity and four individuality traps werewere added.added. The operation of all systems together is explained, starting from the ICE with a coppercopper pipeline reduction from 4 to1 ½ in. of diameter, two safety valves to control the pressure and the pipeline reduction from 4 to 2 in. of diameter, two safety valves to control the pressure and the exhaust gasexhaust flow. gas The flow. gases The continue gases continue their way their to way a heat to exchangera heat exchanger where where the temperature the temperature is reduced is reduced from 60from to 3560 ◦toC. 35 In a°C. straight In a straight way, the way, gases the flow gases through flow twothrough gas condensatetwo gas condensate traps and traps two humidityand two trapshumidity placed traps in series,placed when in series, the gaswhen comes the gas out comes from the out humidity from the trapshumidity it goes trap tos individualit goes to individual humidity trapshumidity for each traps gas. for Theneach thegas. gases Then are the analyzed gases are and analyzed finally and exhausted finally intoexhausted the atmosphere. into the atmosphere. During the process,During the temperature,process, the consumption,temperature, consumption, and rpm of each and test rpm were of recorded. each test Figurewere 2recorded. shows a diagramFigure 2 thatshows explains a diagram the electricity that explains connections, the electricity fuel lines, conn water,ections, air, exhaustfuel lines, gases, water, communication air, exhaust cables,gases, andcommunication equipment used.cables, and equipment used.

Figure 2. Systems set diagram. EnergiesEnergies 2020 2020, 13, 13, x, xFOR FOR PEER PEER REVIEW REVIEW 6 6of of 15 15 Energies 2020, 13, 3594 6 of 14 FigureFigure 2. 2. Systems Systems set set diagram. diagram.

3.3. Results Results and and Discussions Discussions

3.1.3.1. Specific Specific Speciﬁc Viscosity Viscosity of of the the Mixtures Mixtures ToTo determine determinedetermine the thethe viscosity viscosityviscosity of of each each fuel, fuel, three three measurements measurements were were made mademade for for each each sample sample and and an an averageaverage was was obtained. obtained. Figure Figure 3 33 shows showsshows an anan average averageaverage of ofof kinematic kinematickinematic viscosity viscosityviscosity in inin a aa temperature temperaturetemperature range rangerange of ofof 50–9050–90 °C ◦°CC for for B100, B100, D100, D100, and and mixtures mixtures B2, B2, B5, B5, and and B20 B20 [32,35,36]. [[32,35,36].32,35,36]. The The viscosity viscosity of of the the B100 B100 stands stands out out withwith 0.024 0.024 Poise PoisePoise at atat 73 7373 °C ◦°CC and and it it is is 63% 63% higher higher than thanthan the thethe D100. D100.D100.

FigureFigure 3. 3. Viscosity Viscosity vs. vs. temperature. temperature. 3.2. Low Calorific Power of Fuels 3.2.3.2. Low Low Calorific Calorific Power Power of of Fuels Fuels An overall average of the lower calorific power of 44.97 kJ/g was obtained. Figure4 shows that AnAn overall overall average average of of the the lower lower calorific calorific power power of of 44.97 44.97 kJ/g kJ/g was was obtained. obtained. Figure Figure 4 4 shows shows that that the increases in the percentage of biodiesel contained in the mixtures are proportional to the reduction thethe increasesincreases inin thethe percentagepercentage ofof biodieselbiodiesel contcontainedained inin thethe mixturesmixtures areare proportionalproportional toto thethe of calorific values. The value for the B100 sample was 39.08 kJ/g and is close to the value of 37.50 kJ/g reductionreduction of of calorific calorific values. values. The The value value for for the the B100 B100 sample sample was was 39.08 39.08 kJ/g kJ/g and and is is close close to to the the value value of of based on the molecular weight of methyl esters of soybean that are in agreement with those published 37.5037.50 kJ/g kJ/g based based on on the the molecular molecular weight weight of of methyl methyl esters esters of of soybean soybean that that are are in in agreement agreement with with those those in the literature [36–38]. publishedpublished in in the the literature literature [36–38]. [36–38].

5050

4040

3030

2020 LHV (kJ/g) LHV (kJ/g)

1010

00 D100D100 B2 B2 B5 B5 B10 B10 B20 B20 B100 B100

FigureFigure 4. 4. Low Low calorific calorific caloriﬁc values values of of the the fuels. fuels.

3.3.3.3. Raman Raman Analysis Analysis RamanRaman spectroscopyspectroscopyspectroscopy was waswas carried carriedcarried out out toout obtain toto obtaobta informationinin informationinformation about organic aboutabout and organicorganic inorganic andand compounds inorganicinorganic compoundscontainedcompounds in contained B100,contained D100, in in and B100, B100, the D100, diD100,ﬀerent and and mixtures. the the differ differ Figureentent mixtures. mixtures.5 shows the Figure Figure characteristic 5 5 shows shows spectrumthe the characteristic characteristic for D100, 1 spectrumB100, B2, for B5, D100, and B20, B100, where B2, B5, a bandwidth and B20, where in 2800–3000 a bandwidth cm− inis ≈ observed2800–3000 and cm some−1− 1is observed characteristic and spectrum for D100, B100, B2, B5, and B20, where≈ a bandwidth in ≈2800–3000 cm is observed and

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1 −1 somesomepeaks characteristic characteristic at 1450, 1306, peaks peaks 1076, at at and 1450, 1450, 837 1306, 1306, cm− 1076, 1076,are alsoand and observed.837 837 cm cm− 1are Theare also also obtained observed. observed. results The The indicate obtained obtained that results results there indicateindicateis no presence that that there there of is molecules is no no presence presence of other of of molecules molecules substances of of other other and substances our substances results and coincide and our our results withresults those coincide coincide reported with with those inthose the reportedreportedliterature in in [ 39the the,40 literature literature], which [39,40], helps [39,40], us which which to guarantee helps helps us us the to to goodguarantee guarantee quality the the of good good our biodiesel.quality quality of of our our biodiesel. biodiesel.

Figure 5. Raman spectra comparison of D100, B100, B2, B5, and B20. FigureFigure 5. 5. Raman Raman spectra spectra comparison comparison of of D100, D100, B100, B100, B2, B2, B5, B5, and and B20. B20. 3.4. FTIR Analysis 3.4.3.4. FTIR FTIR Analysis Analysis When comparing the spectra of Figure6a,b, characteristic biodiesel signals that are absent in the When comparing the spectra of Figure 6a,6b, characteristic biodiesel signals that are absent in dieselWhen are observed. comparing The the IR spectra spectrum of Figure of PEMEX 6a,6b, diesel characteristic exhibits abiodiesel characteristic signals double that are peak absent at 1457 in the diesel are observed. The IR spectrum of PEMEX diesel exhibits a characteristic double peak at theand diesel 1377 cmare 1observed.. Two groups The ofIR absorptionspectrum of bands PEMEX of the diesel methyl exhibits esters a arecharacteristic shown, and double in the peak region at 1457 and 1377 −cm−1. Two groups of absorption bands of the methyl esters are shown, and in the region 1457of the and ﬁngerprints, 1377 cm−1. Two theband groups is of between absorption 1200 bands and 1300 of the cm me1thyloriginating esters are from shown, the and asymmetric in the region CO of the fingerprints, the band is between 1200 and 1300 cm−1 originating− from the asymmetric CO axial ofaxial the deformation.fingerprints, the In theband region is between of the 1200 functional and 1300 groups cm−1 betweenoriginating 1750 from and the 1730 asymmetric cm 1, the CO intense axial deformation. In the region of the functional groups between 1750 and 1730 cm−1, the −intense peak deformation.peak corresponds In the to region the carbonyl of the func grouptional (C groups=O), so between the characteristic 1750 and 1730 of the cm esters−1, the isintense found peak and corresponds to the carbonyl group (C=O), so the characteristic of the esters is found and related to correspondsrelated to relatively to the carbonyl constant group and interference-free (C=O), so the char stretchingacteristic vibration of the esters [41,42 is]. found This signal and related being the to relatively constant and interference-free stretching vibration [41,42]. This signal being the major relatively constant and interference-free stretching vibration [41,42]. This signal being the major1 major diﬀerence with the diesel spectrum. For both spectra, the absorption band at 2950–3000 cm−1− , differencedifference withwith thethe dieseldiesel spectrum.spectrum. ForFor bothboth spectra,spectra, thethe absorptionabsorption bandband atat 2950–30002950–3000 cmcm−,1 , corresponds to the stretching of the bonds of aliphatic carbons: CH3, CH2, and CH. Additionally, corresponds to the stretching of the bonds of aliphatic carbons: CH3, CH2, and CH. Additionally, the correspondsthe spectra of to soybean-biodiesel the stretching of the mixture bonds areof aliphatic presented carbons: at 2% (FigureCH3, CH6c),2, and 5% (FigureCH. Additionally,6d), and 20% the spectra of soybean-biodiesel mixture are presented at 2% (Figure 6c), 5% (Figure 6d), and 20% (Figure (Figurespectra 6ofe), soybean-biodiesel respectively. A decrease mixture inare the presented intensity at of 2% the (Figure peaks 6c), can 5% be observed(Figure 6d), as and the presence20% (Figure of 6e), respectively. A decrease in the intensity of the peaks can be observed as the presence of biodiesel 6e),biodiesel respectively. increases A decrease in the intensity of the peaks can be observed as the presence of biodiesel increasesincreases

(a()a ) (b(b) ) Figure 6. Cont.

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(e)

Figure 6. Fourier-transform infrared (FTIR) spectra in in transmission mode, mode, characteristic characteristic of of B100 B100 ( (aa),), D100 ( b), and the mixtures B2 (c), B5 (d), and B20 ((e).). 3.5. Results of Fuel Tests 3.5. Results of Fuel Tests Figure7 shows the interface of the VIMEP focus in the characterization of CIE using the diesel- Figure 7 shows the interface of the VIMEP focus in the characterization of CIE using the diesel- biodiesel mixtures. The measuring of the set of parameters is a flexible tool and easily adjustable to the biodiesel mixtures. The measuring of the set of parameters is a flexible tool and easily adjustable to required emission type for a better evaluation of the CIE performance that uses conventional fuels, the required emission type for a better evaluation of the CIE performance that uses conventional biofuel, or both. The system presented is not restricted to engines with a specific capacity, it presents fuels, biofuel, or both. The system presented is not restricted to engines with a specific capacity, it the flexibility of being able to adapt to different CIE. For the above, the following aspects must be presents the flexibility of being able to adapt to different CIE. For the above, the following aspects taken into consideration: operation capacity, fuel consumption, conditions of operation, and used fuel. must be taken into consideration: operation capacity, fuel consumption, conditions of operation, and The VIMEP developed in this investigation is constituted by sensors with a wide range of operation, used fuel. The VIMEP developed in this investigation is constituted by sensors with a wide range of a plotter that allows you to visualize the saved data of realized tests, thus analyzing, comparing, and operation, a plotter that allows you to visualize the saved data of realized tests, thus analyzing, importing in real-time the results of the tests. comparing, and importing in real-time the results of the tests.

Figure 7. Graph of the interface of the VIMEP for the user. Figure 7. GraphGraph of of the the interface interface of the VIMEP for the user.

The result indicates a decrease of calorific value in each mixture: B20 = 2.87%, B5 = 1.33%, and B2 does not present a significant change for diesel, which was the fuel that presents the highest

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Energies 2020, 13, x FOR PEER REVIEW 9 of 15 EnergiesThe 2020 result, 13, x indicatesFOR PEER aREVIEW decrease of calorific value in each mixture: B20 = 2.87%, B5 = 1.33%, and9 of B2 15 does not present a significant change for diesel, which was the fuel that presents the highest calorific value. calorificcalorific value. value. The The increase increase of of 7.7% 7.7% in in the the fuel fuel consumption consumption when when working working at at 850 850 rpm rpm using using the the B20 B20 The increase of 7.7% in the fuel consumption when working at 850 rpm using the B20 mixture [36–38] mixturemixture [36–38][36–38] waswas toto bebe expected,expected, becausebecause thethe didieselesel moleculemolecule has has a a dioxygendioxygen moleculemolecule and and thisthis was to be expected, because the diesel molecule has a dioxygen molecule and this can be reflected in more cancan be be reflected reflected in in more more efficient efficient combustion combustion insi insidede the the combustion combustion chamber chamber of of the the CI-Engine CI-Engine [43,44]. [43,44]. efficient combustion inside the combustion chamber of the CI-Engine [43,44]. As a result, an average AsAs a a result, result, an an average average total total fuel fuel consumption consumption was was obtained obtained for for each each mixture mixture of of B2 B2 = = 1281.92 1281.92 mL/h, mL/h, total fuel consumption was obtained for each mixture of B2 = 1281.92 mL/h, B5 = 1356.58 mL/h, B5B5 == 1356.581356.58 mL/h,mL/h, B20B20 == 1716.371716.37 mL/h,mL/h, andand forfor thethe D100D100 == 1356.581356.58 mL/hmL/h isis shownshown inin FigureFigure 8.8. AnAn B20 = 1716.37 mL/h, and for the D100 = 1356.58 mL/h is shown in Figure8. An average of 14% of O 2 averageaverage of of 14% 14% of of O O2 2emissions emissions was was measured measured for for diesel diesel and and 12 12.7%.7% for for B20, B20, as as can can be be seen seen in in Figure Figure emissions was measured for diesel and 12.7% for B20, as can be seen in Figure9. 9.9.

20002000 18001800 16001600 14001400 12001200 10001000 800800 600600 400400 200200 00 B20B20 B2 B2 Diesel Diesel B5 B5 TypeType of of fuel fuel (ml/h) (ml/h)

Figure 8. Average fuel consumption. Figure 8. Average fuel consumption.

Figure 9. Oxygen emission of the fuels. FigureFigure 9. 9. Oxygen Oxygen emission emission of of the the fuels. fuels. Figure 10 shows the behavior of the CO exhaust gases emitted by the CI-Engine when the diﬀerent mixturesFigureFigure are 10 burned.10 showsshows The thethe amount behaviorbehavior of of emissionsof thethe COCO is exhaexha increasedustust gasesgases when emittedemitted the engine byby thethe load CI-EngineCI-Engine and rpm when increases,when thethe butdifferentdifferent they decreasedmixtures mixtures are whenare burned. burned. the biodiesel The The amount amount concentration of of emis emissionssions of the is is mixtureincreased increased is when increased,when the the engine engine similar load load to the and and results rpm rpm reportedincreases,increases, by but but Di they they et al. decreased decreased [45]. At lowwhen when speeds the the biodiesel biodiesel there is conc aconc lowentrationentration temperature of of the the ofmixture mixture the combustion is is increased, increased, gases similar similar inside to to thethe results combustion results reported reported chamber, by by Di Di et thiset al. al. avoids[45]. [45]. At At the low low CO speed speed becomingss there there is COis a a 2low low[46 temperature ].temperature In general, of of a the reductionthe combustion combustion of CO gases gases was obtainedinsideinside the the by combustion combustion the substitution chamber, chamber, of diesel this this avoids toavoids biodiesel, the the CO CO with becoming becoming an emission CO CO2 2[46]. of[46]. 156 In In ppm general, general, by the a a reduction reduction diesel, 126 of of ppm CO CO bywaswas B20 obtained obtained mixture, by by 139 the the ppmsubstitution substitution by B5 mixture, of of diesel diesel and to to biodie 146biodie ppmsel,sel, by with with B2 an mixture.an emission emission Concerning of of 156 156 ppm ppm diesel, by by the the an diesel, emissionsdiesel, 126 126 ppmppm byby B20B20 mixture,mixture, 139139 ppmppm byby B5B5 mixture,mixture, andand 146146 ppmppm byby B2B2 mixture.mixture. ConcerningConcerning diesel,diesel, anan emissionsemissions reductionreduction waswas obtainedobtained onon averageaverage ofof 1818%,%, 10%,10%, andand 6%,6%, respectively.respectively. InIn general,general, thethe biodieselbiodiesel has has approx. approx. 10% 10% of of the the oxygen oxygen on on a a mass mass basis basis and and has has a a lower lower carbon carbon content content of of carbon carbon

Energies 2020, 13, 3594 10 of 14

reductionEnergies 2020 was, 13, x obtained FOR PEERon REVIEW average of 18%, 10%, and 6%, respectively. In general, the biodiesel10 hasof 15 approx. 10% of the oxygen on a mass basis and has a lower carbon content of carbon than diesel, thusthan the diesel, ignition thus delay the ignition can be shortened,delay can be and shorte the combustionned, and the eﬃ combustionciency increases efficiency with increases the oxygen with in thethe fueloxygen favoring in the the fuel reduction favoring of th COe reduction emissions of [CO47]. emissions [47].

Figure 10. CO emissions of the fuels on average. Figure 10. CO emissions of the fuels on average.

Figure 11 displays the average of SO2 emissions from fuels. There was a difference between Figure 11 displays the average of SO2 emissions from fuels. There was a difference between D100 D100 and B20 with a 2.6% reduction of SO2 [47]. This is because the CIE is working with 850 rpm, severaland B20 authors with a 2.6% agree reduction that being of a SO biofuel2 [47]. ofThis vegetal is because origin the there CIE is is no working sulfur inwith the 850 combustion rpm, several of biodieselauthors agree from that soybean being oil, a biofuel contributing of vegetal to theorigin decrease there is of no sulfur sulfur dioxide in the combustion in the CIE’s of emissions, biodiesel meanwhilefrom soybean for oil, diesel, contributing values were to the up todecrease 20% higher of sulfur than dioxide biodiesel, in andthe CIE’s the results emissions, agree withmeanwhile those reportedfor diesel, in values [47–49 ].were When up theto 20% biodiesel higher concentration than biodiesel, of theand mixture the results percentage agree with increases those thereported oxygen, in the[47–49]. content When increases the biodiesel to bring concentration about a decrease of the in mi combustionxture percentage fumes, increases this explains the oxygen, why the the oxygencontent contentincreases in to the bring fuel about contributes a decrease to the in complete combustion oxidation fumes, ofthis fuel explains [49]. The why variability the oxygen of content the biodiesel in the propertiesfuel contributes can a fftoect the the complete CIE’s in oxidation terms of of gas fuel emissions [49]. The such variability as nitrogen of the oxide biodiesel and properties carbon oxide. can affect the CIE’s in terms of gas emissions such as nitrogen oxide and carbon oxide. The nitric oxide The nitric oxide (NO) is produced in greater amounts and predominates in the NOx production inside the(NO) combustion is produced chamber in greater when amounts the combustion and predominates is performed in the with NOx small production portions inside of nitrogen the combustion dioxide chamber when the combustion is performed with small portions of nitrogen dioxide (NO2). Some (NO2). Some authors measure the NOx, which is the summary of NO and NO2, by a chemiluminescence analyzerauthors measure [50]. The the measurements NOx, which is of the the summary NO of the of exhaust NO and manifold NO2, by a using chemiluminescence commercially available analyzer equipment[50]. The measurements for measurement of the of NO combustion of the exhaus gasest manifold of CIE´s is using considered commercially a good available approximation equipment [51]. for measurement of combustion gases of CIE´s is considered a good approximation [51]. The The experimental studies for measurement have shown that the NOx emissions vary according toexperimental the biodiesel studies composition; for measurement the degree have of saturation shown that of biodiesel,the NOx emissions the longer vary and according more saturated to the biodiesel composition; the degree of saturation of biodiesel, the longer and more saturated chain chain esters increase the cetane number (CN) of biodiesel and tend to decrease the NOx [52]. It is esters increase the cetane number (CN) of biodiesel and tend to decrease the NOx [52]. It is important important to mention that the authors of this work did not focus on analyzing the NOX gas, however, duringto mention thetests that thethe variationauthors of of this this work gas isdid observed, not focus in on [53 analyzing], the authors the NO publishX gas, an however, analysis during of the the tests the variation of this gas is observed, in [53], the authors publish an analysis of the behavior behavior of the NOx, also the portions of optimal mixtures to mitigate the high emissions of this harmfulof the NO gas,x, also also the in portions [52,54–58 of], theoptimal authors mixtures present to mitigate some solutions the high to emissions this problem. of this The harmful biodiesel gas, chemicalalso in [52,54–58], instauration, the the authors biodiesel present oxidative some degradation,solutions to thethis relative problem. stoichiometry The biodiesel the chemical calorific value,instauration, the characteristics the biodiesel of oxidative the fuel spray, degradation, the type the of biodieselrelative stoichiometry (methyl or ethyl the ester),calorific the value, oxygen the characteristics of the fuel spray, the type of biodiesel (methyl or ethyl ester), the oxygen availability, availability, and the levels of aromatic compounds can be factors that influence the NOx emissions, becauseand the oflevels its direct of aromatic effects compounds on flame temperature can be factors inside that the influence combustion the NO chamberx emissions, of the enginebecause [59 of]. its direct effects on flame temperature inside the combustion chamber of the engine [59]. Figure 12 illustrates the results of NO gas emissions not registered in the exhaust manifold on the engine working with all the mixtures. In general, the behavior does not have a significant change in the CO emissions of the engine, although the engine when working with B20 has obtained NO emissions on average of 72 ppm and only 3% less NO emissions than D100.

Energies 2020, 13, 3594 11 of 14 Energies 2020, 13, x FOR PEER REVIEW 11 of 15

Energies 2020, 13, x FOR PEER REVIEW 11 of 15

Figure 11. Average SO2 emissions by fuels. Figure 11. Average SO2 emissions by fuels. Figure 12 illustrates the results of NO gas emissions not registered in the exhaust manifold on the engine working with all the mixtures. In general, the behavior does not have a signiﬁcant change in the CO emissions of the engine, although the engine when working with B20 has obtained NO emissions on average of 72 ppmFigure and only 11. Average 3% less SO NO2 emissions emissions by than fuels. D100.

Figure 12. Average of NO emissions of the fuels.

4. Conclusions

The VIMEP developedFigure is 12.anAverage innovative of NO and emissions flexible of the virtual fuels. instrument based in the Figure 12. Average of NO emissions of the fuels. 4.programming Conclusions platform LabVIEW 2015, which can be adapted to characterize internal combustion 4.engines Conclusions as diesel using biofuel mixtures. The programming of VI that was used is shown in a general way.The The VIMEP VI is trustworthy developed is and an has innovative a low price, and ﬂexiblewith which virtual the instrument rpm, fuel consumption, based in the programming temperatures platformand TheCO, LabVIEW OVIMEP2, NO, and 2015,developed SO which2 emissions is can an be parameters adaptedinnovative to can characterizeand be registered.flexible internal virtual When combustion instrumentthe biodiesel engines based concentration as in diesel the usingprogrammingin the biofuel mixtures mixtures. platform increase, TheLabVIEW the programming calorific 2015, power which of decrea VI can that sesbe was adapted2.8% used for to isB20, showncharacterize 1.3% infor a B5, general internal and 0% way. combustion for The B2. VIFor isenginesviscosity, trustworthy as therediesel and is using an has increase biofuel a low price,of mixtures. 4% withfor B20, The which 2% progra for the B5,mming rpm, and fuel B2of VI consumption,has that the was same used value temperatures is shown as D100. in a and general CO, Oway.2, NO, The and VIB20 is SO mixturetrustworthy2 emissions registered and parameters has a alower low can price, emission be registered.with ofwhich CO Whenthethan rpm, the the fuelD100 biodiesel consumption, emission. concentration This temperatures result in thewas mixturesandobtained CO, increase,O by2, NO, operating and the caloriﬁcSO the2 emissions engine power at parameters decreases 850 rpm 2.8%as can regimefor be B20,registered. because 1.3% for theWhen B5, engine and the 0%biodiesel is fornot B2. submitted concentration For viscosity, to an thereinelectric the is mixtures an charge increase increase,and of does 4% forthe not B20,calorific demand 2% for power B5,power and decrea and B2 hassesthis 2.8% the decrease same for B20, value is 1.3%due as D100.tofor biodiesel B5, and 0% being for B2.a more For viscosity,oxygenatedThe B20 there fuel. mixture is Thean increase registeredlevels of of NO 4% a loweremitted for B20, emission when 2% for the ofB5, B20 CO and is than B2combusted has the the D100 same were emission. value slightly as ThislowerD100. result or like was NO obtainedemittedThe by byB20 operatingburning mixture 100% the registered engine diesel atwith a 850 lower just rpm 3%emission as regimeof NO ofin because ppm.CO than The the enginetheresults D100is obtained notemission. submitted for ThisSO to2 gas result an are electric verywas chargeobtainedsimilar and in by the does operating reduction not demand the percentages engine power at and 850with thisrpm just decrease as2.6% regime of isSO duebecause2 decrease to biodiesel the forengine B20 being comparedis not a more submitted oxygenatedto D100, to thisan electricwas mainly charge due and to thedoes biodiesel not demand being powerobtained and from this a decrease new soybean is due oil, to a biodieselfeedstock being that doesa more not oxygenated fuel. The levels of NO emitted when the B20 is combusted were slightly lower or like NO emitted by burning 100% diesel with just 3% of NO in ppm. The results obtained for SO2 gas are very similar in the reduction percentages with just 2.6% of SO2 decrease for B20 compared to D100, this was mainly due to the biodiesel being obtained from a new soybean oil, a feedstock that does not

Energies 2020, 13, 3594 12 of 14 fuel. The levels of NO emitted when the B20 is combusted were slightly lower or like NO emitted by burning 100% diesel with just 3% of NO in ppm. The results obtained for SO2 gas are very similar in the reduction percentages with just 2.6% of SO2 decrease for B20 compared to D100, this was mainly due to the biodiesel being obtained from a new soybean oil, a feedstock that does not contain sulfur and has more oxygen availability to carry out the combustion process. The emission values obtained are below the limits allowed by the Oﬃcial Mexican Standard NOM-044-SEMARNAT-2017. This result is expected as the engine was mounted on a test bench. The engine was operating in conditions of low and constant speed without power demand. The infrared spectroscopy is an accessible technique that has shown an appropriate methodology to quantify the percentages of biodiesel mixture of cooking oil in a concentration range of 5–70%, taking as standard the increase of the carbonyl group attenuation as the biodiesel mixture concentrations increase. It can be deduced that this concentration range fulﬁlls the law of the Beer–Lambert.

Author Contributions: Substantial contributions to the conception of the results was carried out by A.P. and D.M.; Methodology and analysis was conceptualized out by C.C.; The validation and formal analysis of the results was carried out by M.C. and C.G.; The final approval of the version was evaluated by G.M. and B.V. All authors read and approved the final manuscript. Funding: This research received no external funding Acknowledgments: The authors thank the National Council of Science and Technology CONACYT Mexico, Faculty of Engineering and Technology Sciences, Autonomous University of Baja California, and the Institute of Engineering of the Autonomous University of Baja California for their support in the development of this work. Conflicts of Interest: The authors declare no conflict of interest.

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