EMISSION MEASUREMENT TECHNIQUES IN AUTOMOBILES

Emissions can be characterized, regulated, or controlled only if they can be accurately measured. The increased health and environmental concerns about diesel emissions resulted in the development of a wide range of

measurement techniques of different levels of sophistication, equipment cost and accuracy, to suita variety of applications. Many techniques, especially those used for regulatory purposes, are highly standardized to

produce comparable results even if performed at different testing laboratories. The main types of diesel emission measurements can be grouped as follows:

• Laboratory testing:

• Regulatory testing• Emission research• Engine and emission control

system development

• Field testing:

• Mobile emission laboratories• On-vehicle measurements• Inspection and maintenance (I&M)

programs• Remote emission measurement• Emission-assisted equipment maintenance• Occupational health measurements

INTRODUCTION • Measurements of Emissions - also called source sampling - when a particular

emission source is measured, generally by on the spot tests • Meteorological Measurement - Measures meteorological factors that show

how pollutants are transferred from source to recipient In Delhi, the data shows that of the total 3,000 metric tons of pollutants1 belched out

every day, close to two-third (66%) is from vehicles. Similarly, the contribution of vehicles to urban air pollution is 52% in Bombay and close to one-third in Calcutta.2 Katz (1994) has estimated that in Santiago, Chile, wherever pollution concentration exceeds ambient standards, mobile sources or vehicles are the cause

Traffic exhaust emissions are significant sources of air pollution in the world and may threaten human health and cause global warming effect. Therefore, governments are compelled to minimize motor-vehicle pollution problems with more stringent emission standards for reducing pollution-related chemicals and improving air quality. In most Asian countries, Motorcycles contribute to air pollution more than other vehicles.

ENGINE EMISSION1. exhaust emissions 2. non-exhaust emission

• Exhaust emissions:-  Unburnt hydrocarbon( HC) , Oxides of carbon (CO2,CO) , NO,NO2 ,SO2,SO3 Particulates, soot ,smoke First four are common to both SI and CI engines and last are mainly from ci engine • Hydrocarbons (HC) are emission of unburned petroleum products being released into the

atmosphere.• All petroleum products and made of hydrocarbons (hydrogen and carbon compounds) this includes:• Hydrocarbons are produced because of incomplete fuel combustion or fuel evaporation • Carbon monoxide emission are exhaust emission that is the result of partially burned fuel.• A high carbon monoxide emission can be caused by a:• Restricted or dirty air cleaner.• Advance ignition timing.• Clogged fuel injectors. • Oxides of nitrogen, (NOx) are emission produced by extreme heat.• Air consist of approximately 79% nitrogen and 21% oxygen• When combustion chamber temperature reaches 2500 degrees F or 1370 degrees C 

Tier Date CO THC NMHC

NOx HC+NOx PM P [#/k

m]

Diesel

Euro 1†

July 1992

2.72 (3.16) - - - 0.97

(1.13)0.14 (0.18) -

Euro 2

January 1996 1.0 - - - 0.7 0.08 -

Euro 3

January 2000 0.64 - - 0.50 0.56 0.05 -

Euro 4

January 2005 0.50 - - 0.25 0.30 0.025 -

Euro 5a

September 2009

0.50 - - 0.180 0.230 0.005 -

Euro 5b

September 2011

0.50 - - 0.180 0.230 0.005 6×1011

Euro 6

September 2014

0.50 - - 0.080 0.170 0.005 6×1011

 Petrol (Gasoline)

             

Euro 1†

July 1992

2.72 (3.16) - - - 0.97

(1.13) - -

Euro 2

January 1996 2.2 - - - 0.5 - -

Euro 3

January 2000 2.3 0.20 - 0.15 - - -

Euro 4

January 2005 1.0 0.10 - 0.08 - - -

Euro 5

September 2009

1.0 0.10 0.068 0.060 - 0.005*

* -

Euro 6

September 2014

1.0 0.10 0.068 0.060 - 0.005*

*6×101

1***

* Before Euro 5, passenger vehicles > 2500 kg were type approved as light commercial vehicles 

The Journey Began in 1984 - when the State of Maharashtra introduced norms for idling CO free acceleration smoke.1989- The above norms were extended for the entire country1991 -Exhaust mass emission norms for gasoline for only CO & HC for vehicles below 3.5 ton GVW were introduced

-Full load and free acceleration smoke regulations for diesel vehicles also introduced.1992- Exhaust mass emission norms for diesel vehicles / engines above 3.5 ton GVW introduced1995 -Mandatory fitment of catalytic converter for gasoline Passenger cars in Metropolitan cities.1996 -stringent norms for gasoline (CO, HC + NOx) and diesel vehicles introduced. -Cold start emission test for diesel vehicles below 3.5 ton GVW.1998 -Cold start emission test for gasoline passenger cars introduced1999- India 2000 (Equivalent to Euro-I) norms introduced for passenger cars in National Capital Region (Delhi)2000 - Bharat Stage I norms for all category of vehicles introduced- Bharat Stage II (Equivalent to Euro-II) norms for

gasoline and diesel passenger cars introduced in National Capital Region (Delhi) 

Emission Norms

Multi gas exhaust measurements during cold start conditions • The project is focused on testing and demonstration of exhaust gas measurements in cold

climate using FTIR multi gas exhaust analyzer

• Background• Car producers have expressed a wish to test the cars for e. g. exhaust emissions in cold

climate in cooperation with the vehicle testing companies. The car producers and component producers anticipate that the testing times could be shortened and thereby the testing efficiency can be increased.

• The measurements should be able to be performed during applied testing procedures such as cold start testing. Acceleration and deceleration tests with loading according to applied test

• cycles require a mobile system 4.2 or a full test stand 4.3. The measurements also have to be performed in cold climate.

• The test systems have to handle all kind of vehicles, primarily though passenger cars of different models and brands. The measurement equipment has to be easy to use with short notice and with available trained personnel. One of the most important factors is that the test data has to be managed in a safe way, from the car producer’s point of view. The data should also be available to the car producer shortly after the performed measurements.

Project focus 

The project work is focused on testing instrumentation and demonstration of multi gas exhaust measurements in cold climate. The multi gas measurements are possible to use in mobile field condition as well as in stationary condition on a routine basis. The objective is to demonstrate how cold start measurements (without exhaust gas flow measurement) can be performed with FTIR. The main questions are how to assemble and maintain system/systems for routine measurements by the testing companies which fulfils the requirement of the car manufactures.

  Cold start testing is in certification performed with a sophisticated dynamometers system to obtain the

standard heating rates for the system (including the catalyst). The catalyst starts to work at a certain temperature. Emissions emitted before this temperature gives the cold start emissions. The easiest way to measure could start emissions would be to measure the emissions at idling. If this is not sufficient to give usable data for the car manufactures a brake system would be required, which is very costly. A cheaper system would be to use an onboard measurement system.

 Therefore is the major question; is it required to have a brake system to be able to obtain usable emission

data for the car manufactures and if yes, what is the requirement on the dynamometer system. Or could a mobile system fulfil the requirements and obtain acceptance for real driving tests

  

Performed measurements 

Cold start tests were performed with three different cars with a MKS FTIR instrument (2030 HS) running the instrument at 1 Hz with sampling flow rate of 3 l/min. Further information is given in Appendix. In the figure below is some components shown during a cold start at idling.

Five emission components measured during a cold

start at idling. Conclusions of performed measurements

The measurements were performed without any problems and to obtain faster response the only thing which has to be modified is to increase the sampling flow by increasing size of tubing, pump and filter, compared with what was used in the performed measurements.

 

EMISSION MEASUREMENTS IN INDIAPUC. Emission Testing

• Pollution under Control (PUC) -Under Rule 115 (7) of Central Motor Vehicle Rules (CMVR), 1989, motor vehicles are required to carry PUC Certificate to be given by an agency authorized for this purpose by State Govt.

• Measurement of emissions from petrol vehicle is done by gas analyzer and in case of diesel vehicle emission are measured by smoke meters. There is a list of approved vendors and models of PUC equipment which is compiled and circulated by ARAI, Pune -To ensure that the in-use vehicles are maintained well and less emitting

•Gasoline vehicles are tested for Idle CO emission.•Diesel vehicles are tested for free acceleration smoke

Procedure for PUC tests

• For Diesel vehicles:

• The accelerator should be fully pressed.• The reading of pollution levels should be noted with the acceleration pedal

fully pressed.• The average of five readings is considered as the Final Reading

• For Petrol vehicles:

• The vehicle is kept idling without the accelerator pressed.• Only one reading is taken.

SR. NO.PUC TEST READING

 

VALIDITY

Petrol   Diesel

1 Less than 3 % Les thann.1. 5 %

  Less than 50 Hartridge Smoke Units.

6 Months

3 to 4%   1.5 to 2.5 %   50 to 60 Hartridge Smoke Units

4 Months

4 to 4.5 %   2.5 to 3.00 %   60 to 65 Hartridge Smoke Units

2 Months

Validity of a PUC Certificate

SMOKE FROM THE VEHICLES

 If you see different colored exhaust fumes it’s time to pay attention to your car. Even if your vehicle isn’t flashing any warning lights, the smoke coming from your exhaust is a signal that something might not be working properly.

BLUE smoke from exhaust mean:-

• If your car is blowing blue smoke, it’s a clear sign that the engine is burning oil. What happens is that the valve guide seals or piston rings are worn out, and oil is leaking past from where it should be lubricating the moving parts, to the combustion chamber where it’s being burned up with the fuel.

• If you’re seeing this kind of smoke, check your oil regularly and watch for consumption issues. While an issue that normally should require immediate attention and expensive repairs, including some internal replacement parts, if your vehicle is old and the leak is minimal, it can be carefully managed by topping up the oil on a regular basis.

• Along with environmental damage, burning oil can cause rough starts, as the process can ruin the car’s spark plugs.

• There is another reason for blue smoke, and that’s if the car is turbocharged; the smoke being a sign that the blower is in need of rebuilding or replacement.

GRAY smoke from exhaust mean

• Gray smoke is hard to diagnose directly. Like blue smoke, it can mean that the car is burning oil or suffering from a bad turbocharger. Take the same precautions as with blue smoke, and check for excessive oil consumption.

• Gray smoke can also be an issue with your automatic transmission fluid getting burned up in the engine. A faulty transmission vacuum modulator would be the culprit in this situation, leading to transmission fluid getting sucked into the engine and getting burned up.

• Furthermore, gray smoke could mean a stuck PCV valve. The PCV system (Positive Crankcase Ventilation) cuts down on harmful emissions by recycling them back into the combustion chamber. However, when the PCV valve gets stuck, pressure can build and lead to oil leaks. Fortunately, PCV valves aren’t expensive, and can be a quick job for a mechanic or a do-it-yourselfer.

 WHITE smoke from exhaust mean

• White smoke can be nothing to be concerned about if it’s thin, like vapor. This is probably the result of normal condensation buildup inside the exhaust system. This kind of smoke disappears quickly.

• However, thicker smoke is a big problem, and can be caused the engine burning coolant. This can be the result of a serious issue like a blown head gasket, a damaged cylinder head, or a cracked engine block – all of which are costly repairs.

• Don’t ignore it, however, as the problem could become far worse. Even a small leak in the coolant can lead to overheating and serious risk of damage to the engine. A coolant leak can also mix with oil and cause serious headaches for you and your car.

BLACK smoke from exhaust mean:-

• Black exhaust smoke means the engine is burning too much fuel. The first think you should check is your air-filter and other intake components like sensors, fuel injectors and the fuel-pressure regulator. Other reasons could be a clogged fuel return line. Black smoke is usually the easiest issue to diagnose and fix, but burning unnecessary fuel will definitely affect your fuel economy, so don’t think of avoiding this one to save money, it won’t work.

• Any smoke coming from your car’s exhaust pipe is a sign that your car is in distress. Pay attention to what it needs to ensure more miles for your vehicle.

Smoke emission test (SAE Diesel Smoke Measurement Task Force conducted a test)

 The following sequence of operations shall be performed during engine dynamometer testing for smoke emissions:

   (1)  Control the temperature of the air supplied to the engine to between 80° and 90°F (27° and 32°C). Test only when the observed barometric pressure is between 28.5 and 30.5 inches (724 and 725 millimeters) of mercury in the test area. Starting with an engine at operating temperature, operate the engine at the condition of maximum mass fuel flow, adjust the intake air restriction to within 1 inch (25.4 millimeters) of water of the maximum recommended by the manufacturer and adjust the exhaust system back pressure to within .2 inch (5.1 millimeters) of mercury of the maximum recommended by the manufacturer. Measure and record maximum observed power, fuel rate, engine speed, intake air temperature, intake air restriction and exhaust back pressure.

   (2)  Operate the engine at the intermediate speed. Measure and record maximum observed torque, fuel rate, engine speed, intake air temperature, intake air restriction and exhaust back pressure. Determine by experiment, if not previously determined, the preset loads required by the provisions of § 169.5 (relating to smoke test cycle).

   (3)  Switch on the smoke opacimeter. Allow for the meter circuit to stabilize according to the instruction of the manufacturer. Check the linearity of the meter according to the provisions of § 169.8 (a) (1) and (3) (relating to instrument checks). Mount the smoke opacimeter in accordance with the provisions of § 169.7(b) (relating to equipment and instrumentation) so that the natural flow of the exhaust stream is not disturbed by the meter, the mounting fixture or a ventilation system.

   (4)  pass the exhaust flow through the smoke opacimeter so that the opacity of the exhaust plume may be measured.

   (5)  Operate the engine at maximum power for 10 minutes or until the engine coolant, oil pressures and temperatures are stabilized.

   (6)  Discontinue passing the exhaust gas stream through the meter. Set the zero and span of the smoke opacimeter recorder.

   (7)  Operate the engine in the manner required by the provisions of § 169.5. Continuously record smoke opacity and engine speed on a strip chart recorder or other appropriate instrument. The chart speed shall be at least 1 inch (25 millimeters) per minute during the idle mode and at least 15 inches (381 millimeters) per minute during acceleration and lugging modes.

   (8)  Repeat the procedures as contained in the provisions of § 169.5 (a)—(d) until the entire cycle has been run three consecutive times. If the acceleration and lugging modes have been performed within the tolerances specified in the provisions of § 169.5, then the tests may be terminated at this time. If not, then the test procedure shall be rerun until data have been obtained within the specified limits.

   (9)  Within 1 minute after completion of the requirements of paragraph (8), recheck the calibration of the smoke opacimeter as described in paragraph (6). If either zero or span drift is in excess of 2% opacity, the test results should be considered invalid

Information to be recorded. •  The following information shall be recorded in a test log for each smoke

emissions test conducted:   (1)  Performance data. The following information shall be included:   (i)   Date, time of day, number of engine hours and observers.    (ii)   Barometric pressure and standard dry and wet bulb temperature readings.  (iii)   Maximum observed power, fuel rate, engine speed, intake air restriction, exhaust restriction and intake air temperature at rated speed. (iv) Maximum observed torque, fuel rate, engine speed, intake air restriction and intake air temperature at the intermediate speed.   (v)   Smoke opacimeter type and identifying number.    (vi)  Exhaust pipe diameter.    (vii)   Calibrated and observed values of calibration filter.    (viii)   Other desired information

 (2)  Records.

 The following information shall be recorded on the recorder sheet at the time of each smoke emission test:

     (i)   Test number.

     (ii)   Engine model and serial number.

     (iii)   Engine hours.

     (iv)  Test date and time.

     (v)   Smoke opacimeter type and number.

     (vi) Identify calibration traces and note the value of calibration filter(s).

     (vii)   Identify smoke and speed traces.

Smoke meters 

 • In the filtration type smoke meters like Bosch smoke meter a fixed volume of

the exhaust gas is drawn through a white filter paper of specified quality. The density of smoke stain obtained on the filter paper is evaluated using a reflectance meter which gives the measure of smoke density of diesel exhaust gas. Now, mostly light extinction/absorption smoke meters based on Beer-Lambert Law are used. The light extinction type smoke meters are more commonly called as ‘opacimeters' as these provide a more realistic measurement of the visible smoke emissions from diesel engines. Both the sampling type and full flow type opacimeters are in use. The construction requirements, installation and operational details of opacimeters are described in the relevant international standards. A sampling type smoke meter is shown schematically

 

An incandescent lamp with a color temperature in the range of 2 800 K to 3 250 K or a green light emitting diode (LED) with a spectral peak between 550 nm and 570 nm is used as light source. The transmitted light is received on a photocell or a photo diode (with filter if necessary). When the light source is an incandescent lamp, the receiver should have maximum response in the range 550 nm to570 nm wavelength as is for the human eye. When light from a source is transmitted through a certain path length of the exhaust gas, smoke opacity is the fraction of light that is absorbed in the exhaust gas column and does not reach the light detector of smoke meter. The absolute smoke density is given by the absorption coefficient, ks which has units of m -1 and is given by:

Where L is length of smoke column in meter through which light from the source is made to pass, I0 is the intensity of incident light, I is the transmitted light falling on the smoke meter receiver.In the full flow type smoke meters, the light source and detector are placed directly across the exhaust gas stream usually at the end of exhaust pipe. In this case, path length of smoke measurement varies with the cross sectional size of the exhaust gas stream or tail pipe. Hence, conversion charts of the measured value to the absolute smoke density, KS for different exhaust pipe diameter or path lengths are made available for the full flow smoke meters.

 Constant Volume Sampler (CVS)

Constant volume sampling (CVS) unit using critical flowVenturi (CFV-CVS) for measurement of mass of the exhaust

Emission.

 When emissions are to be measured from a vehicle being run on a driving cycle sampling of the

representative gas is very critical. Constant Volume Sampling (CVS) is used in European, US and other tests to make it possible that a representative sample of the exhaust gas is withdrawn for measurement of the gaseous emissions.

 A Constant Volume Sampling (CVS) system is shown schematically In the CVS system;   

The entire exhaust gas from the vehicle is diluted with the filtered room air. An air to exhaust gas dilution ratio of about 10:1 is used. The dilution with air lowers partial pressure of unburned hydrocarbons and water, and prevents their condensation in the sampling line. 

The diluted exhaust gas is drawn by a constant volume pump system employing either a positive displacement pump (PDP) or a critical flow Venturi (CFV) and a blower. A PDP capacity of about 10 to 12 m3/min of air flow provides sufficient dilution for most passenger cars

  The volume flow rate of the diluted exhaust (exhaust gas + air) is maintained constant Throughout the test.  Before the diluted exhaust gas enters the CFV or PDP, its temperature is controlled within the ± 5 ºC of the

average gas temperature during the test by a heat exchanger. 

From the diluted gas a small sample is continuously withdrawn and collected in evacuated Teflon bags. This process integrates the concentration of the pollutants over the entire driving schedule. A small part of the dilution air is sampled simultaneously and collected in a separate bag to correct for any background concentration of pollutant present in the dilution air.

  

The sample bags are analyzed after the test is completed. 

The mass of individual pollutants is determined from its measured concentration in the sample bag, its density and the total volume flow rate of the diluted exhaust during the test through

   

 

Conclusion

The results of this study give a clear indication that the Implementation of the developed vehicle emission measuring Strategy is not only necessary now but very urgent if any progress is to be made in reducing vehicle emissions in India.

  Strict actions should be taken from the governments on puc measurement center because the

measurements are not perfectly measured and they won’t inform rto about the vehicles which are emitting harmful gases to the atmosphere. And also on the fuel refilling bunks where they mix kerosene to the fuels which is the major problem for vehicle emission.

 More updates are required in the measurements of the automobile exhaust emission. The emission at the rare

side of the vehicles should be known to the driver with the exact percentage of gases emitted to the atmosphere. Emissions measurement is becoming increasingly important for the improvement of diesel engines and petrol

engine development of exhaust gas after-treatment systems. We hope that our measurement systems will serve in the reduction of engine pollution.

 

Bibliography:-  Google.com

Presentation on emission measurement and papers

Wikipedia

Book- Automobile exhaust emission testing

Measurement detection radiation.