Methods in current practice

Diesel Particulate Filter:

Wall-flow diesel particulate filters usually remove 85% or more of the soot, and under certain

conditions can attain soot removal efficiencies approaching 100%. Some filters are single-

use, intended for disposal and replacement once full of accumulated ash. Others are designed

to burn off the accumulated particulate either passively through the use of a catalyst or by

active means such as a fuel burner which heats the filter to soot combustion temperatures.

This is accomplished by engine programming to run (when the filter is full) in a manner that

elevates exhaust temperature In conjunction with an extra fuel injector in the exhaust stream

that injects fuel to react with a catalyst element to burn off accumulated soot and convert it to

ash where it is stored in the DPF filter, or through other methods. This is known as "filter

regeneration". Cleaning is also required as part of periodic maintenance, and it must be done

carefully to avoid damaging the filter. Failure of fuel injectors or turbochargers resulting in

contamination of the filter with raw diesel or engine oil can also necessitate cleaning. The

regeneration process occurs at road speeds higher than can generally be attained on city

streets; vehicles driven exclusively at low speeds in urban traffic can require periodic trips at

higher speeds to clean out the DPF. If the driver ignores the warning light and waits too long

to operate the vehicle above 40 miles per hour (64 km/h), the DPF may not regenerate

properly, and continued operation past that point may spoil the DPF completely so it must be

replaced. Some newer diesel engines, namely those installed in combination vehicles, can

also perform what is called a Parked Regeneration, where the engine increases RPM to

around 1400 while parked, to increase the temperature of the exhaust.

Exhaust Gas Recirculation:

In modern diesel engines, the EGR gas is cooled with a heat exchanger to allow the

introduction of a greater mass of recirculated gas. Unlike SI engines, diesels are not limited

by the need for a contiguous flame front; furthermore, since diesels always operate with

excess air, they benefit from EGR rates as high as 50% (at idle, when there is otherwise a

large excess of air) in controlling NOx emissions. Exhaust recirculated back into the cylinder

can increase engine wear as carbon particulate wash past the rings and into the oil.

Since diesel engines are unthrottled, EGR does not lower throttling losses in the way that it

does for SI engines. Exhaust gas—largely carbon dioxide and water vapour—has a

higher specific heat than air, so it still serves to lower peak combustion temperatures.

However, adding EGR to a diesel reduces the specific heat ratio of the combustion gases in

the power stroke. This reduces the amount of power that can be extracted by the piston. EGR

also tends to reduce the amount of fuel burned in the power stroke. This is evident by the

increase in particulate emissions that corresponds to an increase in EGR.

Particulate matter (mainly carbon) that is not burned in the power stroke is wasted energy. By

feeding the lower oxygen exhaust gas into the intake, diesel EGR systems lower combustion

temperature, reducing emissions of NOx. This makes combustion less efficient,

compromising economy and power. Diesel EGR also increases soot production, though this is

masked by the simultaneous introduction of diesel particulate filters. EGR systems can also

add abrasive contaminants and increase engine oil acidity, which in turn can reduce engine

longevity.

Selective Catalytic Reduction:

Selective catalytic reduction (SCR) is a means of converting nitrogen oxides, also referred to

as NOx with the aid of a catalyst into diatomic nitrogen, N2, and water, H2O. A

gaseous reductant, typically anhydrous ammonia, aqueous ammonia or urea, is added to a

stream of flue or exhaust gas and is adsorbed onto a catalyst. Carbon dioxide, CO2 is a

reaction product when urea is used as the reductant. Diesel exhaust fluid (DEF) is an aqueous

urea solution made with 32.5% high-purity urea and 67.5% deionised. DEF is used as a

consumable in selective catalytic reduction (SCR) in order to lower NOx concentration in

the diesel exhaust emissions from diesel engines

Air Pollution Reduction System Setup:

Physical matter, as in soot and other particulate matters, that is a major constituent of diesel

exhaust, is the second of most harmful constituent of the diesel exhaust. Air pollution

reduction system is a prototype of a system that we suggested, which was to be installed at a

traffic junction where most of the vehicles found are heavy duty diesel vehicles. This system

inhales the exhaust from the atmosphere near the vehicles and passes it through different

layers of filters, at the end of which physical matter as in suspended particulate matter, diesel

particulate matter, soot, etc is filtered. Physically corrected air comes out of the system at the

outlet as per the requirements of PUC. The system is powered by solar energy and battery.

The system is supposedly helpful in reducing the effects of inhaling the particulate matter and

soot on the human body.

Methodology

The work was carried out in four phases:

3.2.1 Phase 1

Drawing of hopper, outlet duct, enclosure.

Drawings of the setup.

Decision on selection of materials required as per setup.

Selection of solar various components(solar panel, battery, dc blower, etc).

3.2.2 Phase 2

Purchasing of MS sheets.

Cutting of MS sheets as per drawing.

Fabrication of hopper, outlet duct and enclosure.

Fabrication of stand for solar panel and battery.

3.2.3 Phase 3

Purchasing of solar panel, DC blower, battery, filters, solar controller, etc.

Assembly of the setup as per the drawing.

Final changes to the enclosure for exhaust inlet.

Completion of circuit powering the setup.

Brought the smoke detector machine on rent.

3.2.4 Phase 4

Experimentation

Smoke meter was placed near the silencer of the experiment vehicle for taking the

readings of smoke density according to the hart ridge units.

The setup was placed near the experiment vehicle and silencer was connected to the

inlet of the setup.

The smoke meter was placed at the outlet of the setup for taking the readings of

smoke density after filtration of exhaust.

Comparison of the readings before and after the application of the setup.

Constructional Features

The structure of the system is made up of MS sheets. The inlet pipe is a flexible rubber pipe,

connected to the enclosure. A hopper is placed at the centre inside the enclosure. At the end

of the hopper, that is at the top of the enclosure, a DC blower is stationed for the suction of

exhaust. An outlet duct is connected to the casing of this dc blower to ensure the exit of

filtered exhaust at a safe distance. The dc blower is connected in series with the solar panel,

solar collector and the battery. Solar panels power the battery and the battery powers the dc

blower. Each component of the system is explained below.

1.Hopper

In general, a hopper is used to guide & stack. In this system we have employed the hopper

for the same function, but by placing it in a inverted way. The main function of hopper is to

guide the exhaust to the inlet of DC blower. Hopper was fabricated from MS Sheet of 1mm

thickness.

2. Outlet Duct

Outlet duct is connected at the outlet of DC blower. The purpose of the duct is to guide the

filtered exhaust coming out of the blower to a safe distance. Outlet duct was fabricated from

MS Sheet of 1mm thickness.

3. Enclosure of the setup

The main purpose of the enclosure is not to allow the exhaust to come out of the system

before it is filtered. The inlet of the system is attached to one of the walls of the enclosure.

Enclosure of the setup was fabricated from MS Sheet of 1mm thickness.

4. Solar Panel, Solar Controller, Battery

PV panel is made of poly crystalline silicon cell. We used the solar panel for charging the

battery in order to run the DC blower. Solar controller is used to limit the rate at which the

electric current is drawn from or added to the batteries. This helps in preventing

overcharging of battery & protects against from over voltage, to increase the performance

and life span of the battery. There are electrochemical cells that are imparted in the battery

which convert chemical energy into electrical energy.

5. DC Blower:

DC blower is used for suction of the exhaust that is guided via the inverted hopper. The DC

blower is powered by the battery.

TESTING & SUMMARY OF RESULTS

Testing:

For the sake of testing we needed a vehicle that used diesel for fuel. One of the college bus

was made available to us. All the following observations and readings were taken from the

college bus. A smoke meter was brought on rent for two days for the testing.

1.The diesel engine (college bus) was started.

2.The smoke meter pipe was inserted in the silencer of the bus and exhaust smoke density

was measured.

3.Keeping the engine on, the silencer of the bus was inserted in the inlet pipe of the enclosure

of setup.

4. Exhaust was made to pass through the filtration system with the help of suction created by

the blower.

5.Smoke meter was connected to the outlet pipe of the system and smoke density was

measured again.

6.The densities of the direct exhaust gas and filtered gas were compared.

Observation:

The unit of the smoke density is Hart ridge unit.

Obs.

no

Time

duration(min)

At silencer

end

At outlet duct Percentage of density reduced

1 2 92 69 25%

2 4 91 67 26.37%

3 6 90 67 25.55%

4 8 90 67 25.55%

5 10 90 66 26.66%

1. After testing, it was observed that the smoke density of the experiment vehicle was found to be

way over the acceptable value of hart ridge unit.

2. The observations show that the readings of the smoke density after passing the exhaust through

the filtration system are approximately equal to 67 hart ridge unit.

3.This value of smoke density is acceptable.

4. The mean smoke reduction by the application of filtration system was 25.82%

DATA COLLECTION / TOOLS / PLATFORMS USED

For this Project i.e. ‘Air Pollution Reduction System’, it was necessary to collect ample data

of different vehicles so that the task of controlling pollution could be made easy. The exhaust

coming out from the vehicles differs depending upon the fuel used. Diesel engines generally

have more pollutants and particulate matter than the petrol engine. Thus, diesel engines were

taken into account for this project.

The main factors on which data collection was necessary were,

a) Diesel Particulate Matter,

b) Suspended Particulate Matter,

c) Soot.

Particulate Matter (PM) is very similar  to smoke in  that it consists of small solids and/or 

liquids  suspended  in  air;  however,  the  sources  of  the  suspended  substances  are  not 

necessarily  the  result  of  burning  organic  substances.

Dust, sand, abraded material from tires and brakes, salt sprays, and even small water droplets 

like fog are some of the other constituents.  PM is usually the terminology used from a regula

torycompliance perspective and may be further subdivided into size related classifications suc

h as PM10, PM2.5, etc. 

The size and amount of particulate matter can be known by knowing the density of the

exhaust air. The more the dense air is, more will be the amount of particulate matter. So, a

Smoke density meter was used to find out the density of exhaust coming out from different

vehicles.

The some density meter was taken to different vehicles and accordingly data was collected.

Trials were done on light duty vehicles & heavy duty vehicles and the data was collected.

Due to unavailability of nitrogen measuring device in the city, NOx emissions were not

measured.

The project consisted of 3 main parts-

a) Enclosure

b) Blower

c) Filters

For construction of chamber 1mm MS sheets were used. The sheets were cut

according to the decided sizes and figures and the welded properly under expert supervision

for perfect finish. The chamber was provided with a hopper from inside which was connected

to the inlet of the blower. The chamber was constructed for accumulation of exhaust gases.

The blower was of 3000rpm. It was used to suck the exhaust accumulated in the chamber.

Filters were used to filter the particulate matters in the exhaust. One filter was fitted at the

entrance of the chamber and other was fitted at the inlet of blower.

Tools used for measurement of particulate matter-

Smoke density meter

Smoke  density  is  a  term  usually  associated  with  opacity  measurements  where there  is 

reason  to  assume  that  the  optical  measurement  relationships  follow  the  Beer‐Lambert 

exponential  laws. The  Beer‐Lambert  Law  is  usually  expressed  as  T=e‐KL  where  T  is 

transmittance  (same  as  1‐opacity/100),  K is  the  smoke  density  factor in  units 

of inverse  length,  and  L  is  path  length  of  the  measured  smoke  sample column.

Conceptually, the smoke density term represents the exponential light loss

sensitivity per unit length of the smoke column. 

Smoke and smoke opacity meters are instruments measuring the optical properties of diesel

exhaust. These instruments have been designed to quantify the visible black smoke emission

utilizing such physical phenomena as the extinction of a light beam by scattering and

absorption. In general, smoke and opacity meters are much simpler (some of them very

simple) and less costly in comparison to most other instruments used for PM measurement.

They are often used to evaluate smoke emissions in locations outside the laboratory, such as

in maintenance shops or in the field. In fact, the smoke opacity measurement is the only

relatively low-cost and widely available method to measure a PM-related emission parameter

in the field. For this reason, opacity limits are used in most inspection and maintenance

(I&M) or periodic technical inspection (PTI) programs for diesel engines. Smoke opacity

limits may be also included as auxiliary limits in new engine emission standards.

In view of the demands of advanced, low emission diesel engines, the following areas of

concern can be identified in conventional smoke opacity meter technology:

Insufficient resolution: Smoke levels in low emission, smokeless diesel engines (e.g.,

Euro IV) are near the resolution of a conventional opacity meter. Resolution, stability,

and noise have to be improved to allow opacity measurements in advanced diesel

engines.

Cross sensitivity to nitrogen dioxide: Catalytic exhaust after treatment devices, such

as oxidation catalysts or particulate filters, can increase the percentage of NO2 in the

total NOx from less than 10% to as much as 40% and more. Nitrogen dioxide absorbs

green light, which is used in conventional opacity meters. Opacity meters read

between 0.00016 and 0.00024 m-1 per ppm NO2, depending on the sensor bandwidth.

A 300 ppm NO2 concentration in a modern engine—not an unrealistic assumption—

would cause a 0.06 m-1 opacity reading, which is equivalent to 40% of the Euro III

EEV pass level, intended to be for soot emissions.

For engines fitted with catalytic particulate filters, nearly all opacity signals will be caused by

nitrogen dioxide.

Insensitivity to small particles: A substantial portion of diesel particles have diameters

below 200 nm. Particles of 200 nm diameter or greater block green light in proportion

to their cross-section surface area. Particles of 50 nm diameters, however, block only

about 15% of their surface area. This means that opacity readings depend on particle

sizes and will be underestimated if smaller particles are measured.

Reduction of particulate matter forms the basic platform of this project. The main idea

of project was to reduce pollution. For this purpose many factors were considered and

the work was done on reduction of particulate matter. Everything was planned

accordingly. The selection of filters, power of vehicles, type of vehicles etc were

selected keeping reduction of particulate matter in mind. As heavy duty vehicles emit

more particulate matter, they can be used to get more convincing results. Smoke

meter will have sufficient amount of matter to work on and thus results will be

clearer.