EXPERIMENTAL TEST SETUP AND METHODOLOGY

Transcription

1 CHAPTER 3 EXPERIMENTAL TEST SETUP AND METHODOLOGY 3.1 INTRODUCTION Controlling strategies for engine emissions are based on both engine design and aftertreatment devices and they need to be evaluated for their controlling efficiency of the finest fractions of particulates and particle number emissions. Assessment of various emission controlling technologies can be possible only if the researchers develop the consensus on the definition of the diesel particulate and also the measurement techniques of its smallest fractions. Measurement of particle number and it s size is much more complex and sensitive to the measurement techniques compared to parameters involved in the measurement of particulate mass. Dilution of the exhaust and it s sampling methods are key variables that must be taken into account for the accuracy and repeatability of the results. Instruments available today for particle size measurement are with better sensitivities compared to the instruments used for PM measurement by gravimetric method. This provides a good option for the PM emission measurement. Measuring methods need to be standardized to measure particulate emissions from advanced engines. Ambient particulate matter is classified based on their aerodynamic diameter in to four main categories. PM 10 are the particulates having an aerodynamic diameter less than 10 μm, fine particles are having diameter below 2.5 μm, and ultrafine particles are of diameter below 0.1 μm or 100 nm and Nanoparticles, characterized by diameters of less than 50 nm. The current sampling techniques used to measure PM 10 maintain the temperature of the diluted exhaust below 52 C. Generally, diesel particulate matters include solids in the form 32

2 of elemental carbon and ash and the liquids in the form of water, sulfuric acid and condensed hydrocarbons. Particulate formation starts with first step as nucleation which occurs in the combustion chamber by carbon soot and ash, and also the nucleation occurs in the dilution tunnel due to presence of water, sulfuric acid and hydrocarbons. Nucleation mechanism could be homogeneous or heterogeneous in nature. The nucleation will be followed by the second step as an agglomeration of these nuclei mode particles. Parameters which affect particle number and size measurement are dilution ratio, rate of dilution, and residence time. The measurement of particle size distribution is a new area in the automotive field. Over the years scientists across the globe gathered more experience on the various methods and instruments used for particle size measurement for their reliability and accuracy. The experience shows that the quality of measurement has been improved in terms of measuring ranges, precision, repeatability and the dynamic response and this will continue further towards betterment. Formation of particulates is a very complex and dynamic process. Various processes involve are nucleation and particle growth which occurs due to adsorption and coagulation. These processes are further influenced by time, temperature, humidity, ambient aerosols etc. Dynamic nature of the particulates is basically because of the process like evaporation and desorption in the ambient atmosphere of volatile particulate fraction. This leads to change in the particle size through various Phenomena and the parameters which are explained above. This dynamic behavior of the particulates brings a real challenge in their measurement accuracy and repeatability. This is totally a different challenge related to measurement of any physical quantity and it s precision. This has been overcome to certain extent by the methodology developed and recommended by WP29, GRPE-PMP group which is also adopted by the new European regulation UN R83 Ver. 4 implemented for Euro Vb and Euro VI emission norms, to measure particle number in addition to PM mass and other gaseous pollutants. 33

3 3.2 TEST EQUIPMENT FOR ROAD LOAD SIMULATION AND EMISSION MEASUREMENT An experimental setup used for particle measurement from vehicles consists of various equipment which are based on recommendations from GRPE-PMP adopted by UN Regulation No.83. These equipment are briefly explained below Chassis Dynamometer The chassis dynamometer model is from M/s. Burke Porter, USA. It s a single axle with 24 inch diameter roller, 150 kw AC motor and variable load curve type used for testing light duty vehicles and passenger cars. Chassis dynamometer simulates inertia electrically for the range from 485 to 5600 kg. This chassis dynamometer has features to carry out both functional as well as emission test on the vehicles for various national and international standards (Refer Plate 3.1) Vehicle Cooling Blower A variable speed type vehicle cooling blower, model 8330, make M/s. Burke Porter, USA used to simulate engine cooling effect inside the test cell for the vehicle under test similar to road by synchronizing the linear velocity of blower wind with the roller speed of chassis dynamometer. The linear velocity of wind at the blower cross sectional outlet and the chassis dynamometer roller speed is within ± 5 km/h as per the regulatory requirements. blower outlet meets the constructional features recommended by the regulation such as cross sectional area of minimum 0.4 m 2 and the bottom of the blower outlet was maintained at 20 cm above floor level and it s distance from front end of the vehicle was adjusted to meet regulatory requirement of 30 cm during actual testing (Refer Plate 3.1) Constant Volume Sampling (CVS) System A critical flow venturi type CVS system, make Horiba, Japan, model T is used for exhaust gas sampling which meets the regulatory requirements. CVS system uses test cell dilution air to dilute the vehicle exhaust by thorough mixing inside the dilution tunnel. It 34

4 satisfies two conditions, it measures total volume of the mixture of exhaust and dilution air and proportional sample of the volume gets collected continuously in the sampling bags and dilution air bag for further analysis purpose. CVS bags are made up of PTFE (Poly Tetra Fluoro Ethylene) which doesn t react with the pollutant in the diluted exhaust gas and meets regulatory requirements (Refer Plate 3.2). Plate 3.1 Chassis Dynamometer & cooling blower Plate 3.2 Constant Volume System Dilute Exhaust Gas Analysis System M/s. Horiba, Japan make exhaust gas analysis system model DLE (Refer Plate 3.4) was used and it meets the following criteria for measuring regulatory pollutants from dilute exhaust gas. Carbon monoxide (CO) and carbon dioxide (CO2) analyzers are of nondispersive infrared (NDIR) principle, hydrocarbon analyzer is of Flame Ionization detector (FID) type. This HC analyzer is with non-heated sampling line for gasoline vehicles and with heated sampling line maintained at 463 K ± 10 K for diesel vehicles which is provided with integrator for continuous measurement, Nitrogen oxide (NOx) analyzer is of Chemiluminescent Detector (CLD) system. All the analyzers in emission analyzer bench meet the regulatory requirements Dilution Tunnel And Particulate Sampling System M/s. Horiba, Japan make full flow dilution tunnel model- DLS 7400 with 48 inch diameter meeting the Euro-3/4 requirements was used during testing (Refer Plate 3.3). Dilution air used to mix with vehicle exhaust is passed through High Efficiency dilution Particulate Air 35

5 (HEPA) filter to clean the dilution air with high efficiency > 99.9%. A pre-classifier is fitted before particulate filter holder to remove the particles above 2.5 µm so as to measure particulates PM 2.5 as per Euro-5b requirements. During PM sampling particulate filter holders are controlled at temperature within 47±5 C by keeping them inside the heated box (Refer Plate 3.5). Plate 3.4 Gaseous sampling & exhaust gas analyzer Plate 3.3 Full Flow Dilution Tunnel Particulate Conditioning Chamber & Micro Balance A Weiss Technik, Germany make particulate conditioning chamber model ET160-VKA/1600/+22DU was used to condition the particulate filters at a controlled conditions of temperature and humidity of 22±3 C and 45±8 % respectively and it confirms to the regulatory requirements. A microbalance of Sartorius make having readability of 0.1 µm was used for measuring the particulates PM Particle Number (PN) Measurement Equipment Highly sophisticated instruments used to measure the ultrafine and nanoparticles in terms of number and size especially on transient cycle are briefly explained below. Various equipment used for PN and size measurement are shown in Plate

6 Plate 3.5 Heated PM filter holder & VOC sampling Plate 3.6 PN and size measurement Volatile Particle Remover (VPR) VPR model MD19-2E is from TSI, USA and it conforms to GRPE-PMP requirement was used for the experimentation is shown in Plate 3.7. VPR receives the diluted exhaust gas sample from pre-classifier. It has two diluters and evaporation tube in between. The first stage is hot dilution (PND1) uses thermo diluter maintained at a temperature >150 C, which reduce thermophoretic losses. Diluted exhaust gas sample is passed through evaporation tube which is maintained at temperature 300 ±1 C in order to remove volatile particles. In the next step a cold dilution at a temperature <35 C is carried out using PND2 which receives diluted exhaust gas sample from evaporation tube. Parameters that affect particle number measurement are sampling techniques, dilution factor, relative humidity and temperature of the dilution air. Temperature controls at the PND1, PND2 and evaporation tube ensures that there is no condensation at cooling down zone; this is to maintain repeatability and reliability of the measurements Condensation Particle Counter (CPC) Condensation Particle Counter model 3790 EECPC shown in Plate 3.8 was used for measurement of real time particle count with a size range between 23 nm to 3 μm and has resolution of 0.1 particles. CPC has sensitivity of measuring single particle count with maximum precision in full flow operation at 1.0 l/min sample flow rate. The Condensation Particle Counter used for the experimentation conforms to GRPE-PMP requirements. Particles in the diluted exhaust when travel through the path inside CPC it adsorbs vapor of 37

7 butanol and grow in size so that it can be detected easily. Further when the particles passed through optical path they scatter the light which gets detected by photovoltaic cell receiving the light. CPC has maximum range of particle concentration 1x10 4 particles/cm 3. CPC is calibrated conforming to the requirements of PMP requirements and has fast response to rapid changes in aerosol concentration (T95 < 3 seconds). Currently, regulation has decided to use cutoff of 23 nm particle size, means to measure all the particles above 23 nm. This is to improve the repeatability and reproducibility of the measurement procedure. This measures primary soot particles and to exclude volatile nucleation mode particles which are more dynamic in nature (Giechaskiel B. et al., 2015). Plate 3.7 Volatile Particle Remover (VPR) Plate 3.8 Condensation Particle Counter (CPC) Particle Size Measurement By EEPS Currently, there is no regulatory requirement to characterize the particulates in terms of their size. In this experimental study, TSI make engine exhaust particle sizer model EEPS 3090 shown in Plate 3.9 was used for particle size measurement. EEPS is a fast response particle sizer. It has 32 size channels which spread between 6 nm and 523 nm used for real time measurement at a sampling rate of 1 Hz. EEPS works on the Electrical mobility principle where the multiple electrometers measure the particle size and their concentrations. EEPS software can provide other derived parameters of the particulate metrics in terms of surface area and volume. Plate 3.10 shows various configurations of online data formats and graphics available on the equipment GUI. The graphic user interface (GUI) shown below in plate 3.10 gives statistical table with second by second data for particle size and PN concentration, chromatograph for instant information on PN concentration, histogram and cumulative PN concentration curve. 38

8 Plate 3.9 Engine Exhaust Particle Sizer (EEPS) Plate 3.10 Various formats on EEPS GUI Confirmation of Test Setup in line with Regulatory Requirements Various features of individual equipment and overall test setup was ensured for the completeness in line with Indian emission legislation MoRTH/CMVR/ TAP-115/116 and European emission regulation UN Regulation No.83 Rev.4, which are briefly described below. 3.3 Consumables For Experimentation Availability of following consumables essential for the experimentation was ensured. A) Analyzer Operating and Calibration Gases - Pure nitrogen (purity 1 ppm C, 1ppm CO, CO ppm, and 0.1 ppm NO); - Pure synthetic air (purity 1 ppm C, 1ppm CO, 400 ppm CO 2, 0.1 ppm NO); oxygen content between 18% & 21% Vol.; - Pure oxygen (purity 99.5 per cent Vol. O 2 ); - Pure hydrogen (and mixture containing H 2 ) (Purity 1ppm C, 400 ppm CO 2 ); B) Span gases used for Analyzer calibration (for true concentration within ± 2%): Following chemical compositions of gases were ensured for availability required for calibration of various analyzers. - C3 H8 and purified synthetic air, as mentioned above - CO and purified nitrogen & CO 2 and purified nitrogen 39

9 - NO and purified nitrogen ( NO 2 contained in calibration 5% of NO content) C) Particulate Filter Papers Particulate filters of Pallflex, make Germany of 70 mm diameter were used to conduct the tests, confirming to regulatory requirements. D) Test Fuels Euro-3 and Euro-4 gasoline and diesel Euro-3 fuels were ensured for their sufficient stocks availability before the tests. Commercial CNG was also ensured for CNG vehicle testing. Technical specifications of the gasoline and diesel fuels used are given in Appendix I and Appendix II respectively. 3.4 FINALIZATION OF TEST MATRIX As per the objective of the study under taken the test matrix finalized is given below in Table 3.1. The test matrix is based on 4 different variables viz. vehicle type, vehicle technology, fuel type, and test cycle. Each variable is of different levels as mentioned below. First variable is a Vehicle Type which is of level 3 and these include three different types of vehicles: viz. Gasoline vehicles, Diesel vehicles and CNG vehicle. Second variable is a Vehicle Technology which is of level 3 for the vehicle technology to be selected among the vehicles available in the market, either Bharat Stage-2 (BS-2) or Bharat Stage-3 (BS-3) or Bharat Stage-4(BS-4). Third variable is a Fuel Type which is of level 4 and these include diesel (Euro-3), gasoline (Euro-3 & Euro-4) and CNG commercial type. Fourth variable is a Test Cycle which is of level 1 and this is current Modified Indian Driving Cycle (MID) All the test vehicles mentioned in the test matrix were directly sourced from their owners and tested on the chassis dynamometer using the current regulatory test cycle known as Modified Indian Driving (MID) Cycle. The finalized test matrix is given in Table

10 Table 3.1 Finalized Test Matrix Vehicle Category Vehicle Technology Test Fuel (Reference /Commercial) Number of Vehicles Number of Tests Test Cycle Responses to be measured Gasoline Diesel CNG BS-2/BS-3/ BS-4 BS-2/BS-3/ BS-4 BS-2/BS-3/ BS-4 Fuels available among Euro-2 / Euro -3/ Euro-4 Fuels available among Euro-2 / Euro -3 / Euro- 4 Commercial CNG Max. 2 Nos. Max. 2 Nos. Total 2 Tests Total 2 Tests 1 Nos. Total 1 Tests MID cycle A)Gaseous Pollutants: (CO, THC, NOx, CO 2 ) B)Particulates (PM 2.5, PN, Size, surface, Vol.) C) PM 2.5 elemental Analysis: (SOF, IOF, PAH) on one of vehicle from each category Test Matrix is based on 4 different factors and their respective levels mentioned below: 1) Vehicle Technology: 3- Levels (BS-2, BS-3, BS-4 technology vehicles were tested) 2) Vehicle Type : 3- Levels (Gasoline, Diesel, CNG) 3) Fuel Levels: For Gasoline & Diesel (3-levels Euro-3 & Euro-4 and CNG commercial was used) 4) Test Cycle : 1-Level ( MID Cycle applicable for India was followed) Total Number of Tests on 5 different vehicles : 5 The responses to be measured during actual test are mentioned in the test matrix, this includes measurement of regulatory pollutants like CO, HC, NOx and CO 2, particulates PM 2.5, Particle Number (PN). Additionally, other attributes of particles in terms of particle size, volume and surface area were measured. Elemental analysis of PM 2.5 was carried out by chemical analysis for each fuel to measure SOF, IOF and PAH, aldehydes + ketones, 1-3 butadiene and benzene. Figure 3.1 below shows graphical representation of Modified Indian Driving (MID) Cycle to be followed during actual testing. Phase wise break down of the driving cycle is in Appendix III along with the information on various important parameters of driving cycle viz. rate of accelerations, decelerations, average speed, and % time in each phase etc. 41

11 Figure 3.1 Modified Indian Driving (MID) Cycle 3.5 TEST METHODOLOGY Experimental setup and consumables required to start the actual experimentation as per the test matrix mentioned above in Table 3.1 were ensured for completeness and availability. Currently, India is following Bharat Stage-4 emission norms for light duty vehicles including passenger cars. In Europe since Euro-5 emission regulation as per UN R83 Rev.4 was enforced and particularly Euro-5b was mainly an amendment to introduce the measurement of PM 2.5 and particle number specifically from diesel and direct injection gasoline vehicles. The test procedure and methodology adopted for the research work planned here was based on UN Regulation No.83 Rev.4 which has adopted the guidelines and recommendations from particulate measurement program (PMP) which is sub group under WP.29 - GRPE (A Working Group on Energy and Pollution under world Form for Harmonization of Automotive Regulations) under United Nations. The Automotive Research Association of India, which is India s premier institute and engaged in certification and research and development, has recently established advanced facilities with the help of Ministry, Department of Heavy Industry, Govt. of India to measure the particles in terms of number, size, surface and volume. This national level facility used to carryout research work, the details of equipment are given in Appendix IV. This facility was ensured for the various features and equipment required to carry out the 42

12 experimental work planned under the scope of research study. The technical details verified for the facility are given in Appendix IV. The schematic of experimental test setup is given below in Figure 3.2. Vehicle Soaking Area and Test Cell Conditions: Vehicle soaking area was confirmed for the regulatory requirements of temperature control within 20 C and 30 C, this meets regulatory requirements Test Cell Conditions: Temperature: 20 and 30 C and Absolute Humidity: 5.5 H 12.2 g H 2 O/kg dry air Figure 3.2 Schematic of Experimental Test Setup Summarization of status reviewed on the equipment in the experimental setup and the necessary consumables required to carry out experimentation is given in the Table 3.2 below. 43

13 Table 3.2 Summarization of Status For Equipment and Consumables Test methodology followed during actual vehicle testing is given in the flow diagram at Figure 3.3 which is self-explanatory. Test vehicles were sourced mainly from the users as per the test matrix depending on the testing slot available in the laboratory which was running with very busy schedule. However, based on the discussion had with the Head Emission Lab, ARAI the test vehicles mentioned for technical details in Appendix V were sourced and testing was carried out on chassis dynamometer using the test setup and the methodology finalized and explained in this Chapter 3. For vehicle testing on chassis dynamometer we need two parameters to be given as input to chassis dynamometer GUI viz. vehicle inertia and road load coefficients. To calculate inertia of the vehicle, first calculate reference mass of the vehicle as per the Indian emission regulation MoRTH/TAP-115/116. Reference Mass of the vehicle = Unladen mass of the vehicle kg (Pay load) Using this calculated reference mass and referring to Appendix XII which gives a table for reference mass and equivalent Inertia we can get the value of the equivalent inertia to be simulated on the chassis dynamometer. The road load coefficients obtained by the coast 44

14 down method on the road are taken from their type approval reports for these vehicle models which were already certified by ARAI. Road load equation for the vehicle model is a very important and it s an essential part to simulate road load on the chassis dynamometer. The general form of road load equation is F = a + b*v 2 + I *dv/dt where, a = frictional coefficient of tire with road surface, b = aerodynamic resistance and I = vehicle inertia Figure 3.3 Flow Diagrams Test Methodology 45

15 Figure 3.3 Flow Diagrams Test Methodology Following Table 3.3 contains the details of vehicles tested, their un-laden weight, inertia calculated and road load equations used during actual testing on the chassis dynamometer. The inertia to be simulated is obtained by referring the term (ULW+ Pay load) to inertia range table given in Appendix XI. Test procedure followed is based on Indian Emission Regulation Document MoRTH/TAP-115/116 which is harmonized with European Regulation UN R83 followed for the measurement of gaseous pollutants, whereas, specifically, UN R83 Version 4.0 was used for the measurement of PM 2.5 and Particle number (PN), which is yet to be implemented in India. The flow diagram given in Figure 3.3 for the test methodology is covered briefly to explain the procedure followed. 46

16 Table 3.3 Details of Vehicles Tested Inertia and Road Load Parameters ID Technology Test Fuel Model Year Vehicle Details ULW + Pay load Road Load Equation Inertia (kg) Odometer (km) 4WG1 BS-2 Euro-3G F = V dv/dt 4WG2 BS-4 Euro-4G F = V dv/dt 4WD1 BS-3 Euro-3D F = V dv/dt 4WD2 BS-3 Euro-3D F = V dv/dt 4WC1 BS-3 CNG F = V dv/dt Fuel: Euro-3G / Euro-4G means Euro-3/ Euro-4 gasoline, Euro-3D means Euro-3 diesel After receipt of test vehicle, the relevant information about the vehicle test parameters like, road load equation, inertia, tire pressure to be set were collected and vehicle was inspected for no leakage on intake and exhaust side, checked oil level, drained the tank fuel and fill the test fuel as per the test matrix. Initially, vehicle was driven for trial run to purge the fuel lines with new fuel and also to ensure that vehicle has no problem for it s drivability. Then vehicle was mounted on the chassis dynamometer, the relevant test parameters were set on the dynamometer user interface, appropriate CVS venturi was selected, dilution sampling (DLS) flow was set. After warming up of chassis dynamometer for minimum 30 minutes coast down was carried out on chassis dynamometer to ensure that road load simulation for the vehicle is within regulatory limit of ±5% to the point. Next, preconditioning of the vehicle was carried out on the chassis dynamometer. After completion of preconditioning the vehicle was shifted to soak room where, soaking was carried out for minimum 6 hrs. for a controlled temperature of 20 C to 30 C before conducting actual emission test. Test vehicle soaked in the soak room is shifted with engine OFF condition to test cell and mounted on chassis dynamometer for emission test. Relevant MIDC test cycle was set on driver s aid to be followed during actual test. All the equipment in the setup are once again ensured for their operating status and parameters to be set. Analyzer bench was calibrated for zero and span with the known concentration of gases for CO, HC, NOx, and CO 2. 47

17 Conditioned PM filter papers were weighed and mounted in the filter holders were fixed inside heated filter box whose temperature was ensured at 47±5 C. Also, all the nanoparticle measurement equipment viz. VPR, CPC and EEPS were observed for their readiness to start the measurement. Sampling system for collecting the sample for chemical speciation was also made ready. Test cell ambient conditions were confirmed for temperature between 20 and 30 C, absolute humidity between 5.5 to 12.2 g of H 2 O/ kg dry of air. Once, the whole test up was confirmed for readiness, a test was started, all the measuring and sampling equipment viz. CVS bags for ambient and dilute exhaust sampling, PM filter holders, CPC and EEPS, VOC sampling, driver s aid and vehicle cooling blower were ensured for their synchronized start which was through test cell automation and no malfunction or delay observed during the process. Here, variable load curve A.C. motor type chassis dynamometer used to simulate the required inertia and the engine cooling effect is simulated by vehicle cooling blower whose linear velocity of wind is synchronized with roller speed. A critical flow venturi (CFV) type Constant Volume Sampling System (CVS) maintains a constant flow rate of diluted exhaust gas throughout the driving cycle. A small sampling venturi inside the CVS system takes a proportionate sample of dilute exhaust from the main diluted exhaust gas stream which gets collected into CVS bags for further analysis using dilute exhaust gas analysis system at the end of test to measure the concentrations of various gaseous pollutants. Analyzer system was calibrated before and after the test to ensure that there is no drift in the measuring equipment. To measure PM 2.5 a full flow dilution tunnel was used which is supplied with dilution air that gets filtered by passing it through HEPA filter. Next, this diluted exhaust gas sample was passed through pre-classifier (PCF) to remove particles above 2.5 µm and further this sample was passed through PM filter holders fitted with fluorocarbon coated glass fiber filters to collect the particulates on it. After completion of the test PM filter papers were transported for conditioning to PM conditioning chamber where they were conditioned for minimum 1 hr at controlled conditions of temperature and humidity, and then weighed on micro balance to measure the mass of PM2.5. A volatile particle remover (VPR) receives sample from pre-classifier removes volatile and semivolatile particles in the diluted exhaust gas stream using evaporation tube which is maintained at a temperature above 300 C. This diluted exhaust containing solid particles is then subjected for measurement of particle number at condensation particle counter and for 48

18 particle size and their respective PN concentrations at Engine exhaust particle sizer. Engine Exhaust Particle Sizer (EEPS) measures particle concentration over 32 different particle sizes between 6 nm and 523 nm. EEPS also gives data for derived parameters like particle surface area and volume. CPC and EEPS generate the log files over the complete test cycle which will be available at the end of the test for further calculations and analysis. After PM 2.5 measurement the particulate filter papers were transported to the chemical laboratory for further chemical analysis to determine the chemical constituents of particulate matter in terms of IOF, SOF, PAH, aldehydes+ketones, 1-3 butadiene and benzene. Chemical characterization of PM was carried out off-line by chemical analysis method. The schematic of it shown below in Figure 3.4 which is based on the following steps: (1) preparation to collect the substrates (2) DNPH impingers for exhaust sampling (3) PM extraction from the substrates, and (4) chemical analysis of the recovered material. Here, the second step is specifically based on regulatory recommendations. For remaining three steps no regulation but standard analytical chemistry protocols was followed. Currently, there is no single analytical method capable of detecting all the chemical species in diesel exhaust. After gravimetric measurement of PM, both primary and secondary filter papers were first subjected to soxhlet extraction process to obtain the particulate extract using 80:20 benzene to methanol mixture, this process takes around 72 hrs. After extraction both these filter papers were dried at temperature of 700 C for 3 hours and their weights were taken to determine the soluble organic fractions (SOF) and insoluble organic fractions (IOF) in the particulates. 2,4-dinitrophenylhydrazine (DNPH) impinge cartridges were used to collect the gaseous sample during vehicle test. An impinger and extracted samples were dissolved in 1ml of acetonitrile separately and the sample was injected in the High Performance Liquid Chromatograph (HPLC) analyzer, shown in Fig. 3.4, which carries out the analysis by using ultraviolet detector and suplecosil and C-18 columns. The sample collected in impinger containing absorbing solution (2,4 DNPH) complexes the carbonyl compounds viz. aldehydes and ketones into their diphenyl hydrazine derivatives. The solution in impinger is then transferred to a sample bottle which is further injected in High Performance Liquid Chromatography (HPLC) analyzer. A traceable Certified Reference Material (CRM) specifically having concentration of target carbonyl compound to be measured in the sample was used to calibrate HPLC analyzer. Volatile organic compounds (VOC) like benzene and 1,3 butadiene in exhaust gases were determined using active 49

19 sampling onto sorbent tubes. The measurement method involves drawing of a known volume of exhaust gas through a stainless steel tube to collect VOC s like Benzene & 1,3 butadiene followed by a Thermal Desorption Capillary GC- FID analytical procedure. Adsorbent materials of the tube used to concentrate desired analytes are selected on the basis of their affinity. Figure 3.4 Flow Diagrams for Chemical Speciation of Particulate Matter 3.6 DATA COLLECTION AND CALCULATIONS As per the plan initially 4WD1 diesel vehicle was tested on the chassis dynamometer using the methodology explained above. A template was generated to collect the data systematically so as to maintain the uniformity and to follow the regulatory steps. Calculation software was prepared in MS Excel which is based on the regulatory steps for calculating the mass emissions of all gaseous pollutants viz. CO, HC, NOx & CO 2, particulate matter (PM) and particle number (PN). 50

20 3.6.1 Collection Of Data For Gaseous Pollutants A template generated and used during experimentation for observation and calculations is shown below in Figure 3.5 to Figure 3.10 as an example for 4WD1. For other tested vehicles 4WD2, 4WG1, 4WG2 and 4WC1 their respective observations sheets and calculations are given in Appendix VII to Appendix X Calculation of Gaseous Pollutants The mass emission of the pollutants CO, HC, NOx and CO 2 are calculated by using following equation as per Chapter 8 of Annexure XIV of Indian Emission Regulation TAP/ M i = ( V mix * Q i * C i * 10-6 ) / d Here, Mi = Mass emission of the pollutant i in g/km V mix = Volume of the diluted exhaust gas corrected to standard conditions of 293K and kpa and is expressed in m 3 /test Qi = Density of the pollutant i in kg/m 3 at NTP (293 K and kpa) k H = Humidity correction factor used to calculate mass emissions of oxides of nitrogen There is no humidity correction for HC and CO. kh = 1 / ( * (H 10.71)) & H = (6.211*Ra * Pd) / (PB Pd * Ra * 10-2) Where: H = Absolute humidity expressed in grams of water per kg of dry air R a = Relative humidity of the ambient air in percentage P d = Saturation vapor pressure at ambient temperature in kpa P B = Atmospheric pressure in the room in kpa C i = Pollutant concentration in the diluted exhaust gas in ppm and corrected by the amount of the pollutant i contained in the dilution air. Pollutant concentration in the sampling bag to be corrected as follows C i = C e - C d ( 1-1/D F ) where: C e = Concentration measured in the diluted exhaust gas in ppm of pollutant i. 51

21 C d = Measured concentration of pollutant i in the air used for dilution in ppm. D F = Dilution factor The dilution factor shall be calculated for various fuels as follows: D F = 13.4 / ( C CO2 + (C HC + C CO ) * For petrol and diesel D F = 9.5 / ( C CO2 + (C HC + C CO ) * For CNG d = distance travelled in km Figure 3.5 Test Observation Sheet for Vehicle 4WD1 52

22 Figure 3.6 Test Data for Gaseous Pollutants Measured from Vehicle 4WD1 Figure 3.7 Calculations for Gaseous Pollutants Measured from Vehicle 4WD1 53

23 Figure 3.7 Calculations for Gaseous Pollutants Measured from Vehicle 4WD Collection Of Data For Particulates PM 2.5 And PN Figure 3.8 Test Data for Particulate Matter (PM 2.5 ) Measured from Vehicle 4WD Calculation Of Particulate Emission Here: Particulate emission Mp (g/km) is calculated by means of the following Equation. Mp = (Vmix + Vep) * Pe / (Vep * d) If exhaust gases are vented outside tunnel. M = (Vmix * Pe) / (Vep * d) If exhaust gases are returned to the tunnel. V mix = volume of diluted exhaust gases under standard conditions 54

24 V ep P e = volume of exhaust gas flowing through PM filter under STP = particulate mass collected on the filters in g d = distance travelled in km M p = Particulate emission in g/km Figure 3.9 Calculations for Particulate Matter (PM 2.5 ) Measured from Vehicle 4WD Calculation Of Particle Number (PN) PN emission are calculated as : PN = (V mix * K * PN Con_Corr * Fr Avg * 10-3 ) / d Where: PN = particulate number expressed in particulates per kilometer V mix = volume of the diluted exhaust gas corrected to STP K = Calibration factor to correct the PNC measurements K=1, If calibration factor is applied internally within the PNC PN Con_Corr = Corrected concentration of PN in the diluted exhaust gas in terms of average particulates per cubic centimeter figure over total duration of test cycle. If volumetric mean concentration results ( C ) from PNC are not at STP of K and kpa, then correct it C i n i 1 n C i Where: C i = Instantaneous measurement of particulate concentration in the diluted gas exhaust from PNC (particulates/cc) n = total number of instantaneous particulate concentration measurements made over entire driving cycle 55

25 n = T * f Here, T= time duration of the driving cycle in seconds f = data logging frequency of the particulate counter expressed in Hz Fr Avg = Mean particulate concentration reduction factor of VPR d = distance travelled in kilometers, PN Con_Avg = shall be calculated from the following equation: Figure 3.10 Calculations for Particulate Number (PN) Measured from Vehicle 4WD1 56

26 3.7 TEST RESULTS FOR THE VEHICLES TESTED Table 3.4 given below summarizes the emission results obtained for the vehicles tested on the Modified Indian Driving Cycle as per the test matrix Test Results For Gaseous Pollutants, PM 2.5 & metrics, PN and Idling Emissions Table 3.4 Test Results for Gaseous Pollutants, PM 2.5, PN, Particle Surface area & Volume Vehicle ID Pollutants in g/km Particle Metrics Idling Emissions CO HC NOx CO 2 PM 2.5 PN ( km -1 ) Surface Area nm 2 /cm³ Volume nm³/cm³ FA Smo ke %CO HC ppm 4WG E E E+09 NA WG E E E+09 NA WD E E E NA NA 4WD E E E NA NA 4WC E E E+11 NA Test Results For PM 2.5 Elemental Analysis by Chemical Method Total 5 tests on 5 different vehicles of various technologies operating on Euro-3 & Euro-4 fuel levels as per test matrix were completed as per the scope. Further, PM 2.5 elemental analysis was carried out at the chemical laboratory to obtain the various constituents of the particulate matter in terms of SOF, IOF and Poly-aromatic Hydrocarbons (PAH), Aldehydes + ketones, 1-3 Butadiene, and Benzene contents. VOCs and semi volatile organic compounds (SVOCs) are an additional large class of pollutants. SVOCs are found in both the gas and particle phase. They are associated with combustion, fugitive emissions and with secondary formation. Some of these compounds are benzene, toluene, xylene, 1,3-butadiene, and polycyclic aromatic hydrocarbons. EPA has listed 188 hazardous air pollutants and VOCs are among them. Hence, some of them are incorporated in the study The test results are given below in Table

27 Table 3.5 Test Results For Elemental Analysis Of PM 2.5 By Chemical Analysis Vehicle ID SOF IOF PAH Aldehydes+ Ketones 1-3 Butadiene Benzene µg µg µg µg µg µg 4WG WG WD WD WC Raw data files for all the tested vehicles for particle number concentration and it s derived parameters like surface area and volume were available with large data which were analyzed after configuration of the data for the analysis purpose this is explained in the next Chapter 4. 58