CHAPTER 1:
INTRODUCTION
1.1 Introduction:
Manufacturing of a vehicle is done for variety of purposes; it is to transport people, goods, etc. There are also a various number of factors that go into the manufacturing process. These factors have a direct influence on the design of the vehicle. one of the major factors that affect the design of the vehicle are geographical conditions, where the car is going to be used makes a huge impact on what conditions the car is going to face. This dissertation will focus on the design implications for the vehicles in the Middle East. Overview of the various problems and discussion on the impact on the air intake and filters considering the conditions and legislations of the Middle East will be discussed.
1.2 Project Aim:
The aim of this project is to shed light on the implications on the design of the vehicles for various issues and factors. To focus on the air intake and possibly find a model solution with CFD analysis.
1.3 Project Objective:
To identify the problems, and how they are being handled
To focus on the Air Filters,
To research on the methods that is being currently used to combat this issue.
CFD analysis to find a model solution.
To study the various legislations, and environmental/health issues of emissions
To research and suggest more efficient methods, if possible with an improved design.
To discuss the results of the new suggested designs.
Chapter 2:
Literature Review
2.1 Introduction:
The issues faced in the design for vehicles in the Middle East are majorly based on the geographical factors such as the weather, and the dessert terrain etc. What we need to focus on is to try and overcome these problems and create modifications and variations onto the model of the vehicle, so as to accommodate for the conditions.
One of the major issues faced by the Vehicles in the Middle East is that the air conditions are high in dust and other particles as compared to the conditions in the western countries. There are different ways that the vehicles try to make up for the weather conditions.
The importance of air filters is realised by only a few people in general. The performance of the engine is based on how neatly the air fuel mixture is blended. If the air filter is dirty it might cause the mixture to be too rich and that might result in choke, which can damage the engine severely.
2.2 Air Filter:
A particulate air filter is a device composed of fibrous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air. A chemical air filter consists of an absorbent or catalyst for the removal of airborne molecular contaminants such as volatile organic compounds or ozone. Air filters are used in applications where air quality is important, notably in building ventilation systems and in engines.
Some buildings, as well as aircraft and other man-made environments (e.g., satellites and space shuttles) use foam, pleated paper, or spun fibreglass filter elements. Another method, air ionisers, use fibers or elements with a static electric charge, which attract dust particles. The air intakes of internal combustion engines and compressors tend to use paper, foam, or cotton filters. Oil bath filters have fallen out of favour. The technology of air intake filters of gas turbines has improved significantly in recent years, due to improvements in the aerodynamics and fluid-dynamics of the air-compressor part of the Gas Turbines.
The cabin air filter is typically a pleated-paper filter that is placed in the outside-air intake for the vehicle's passenger compartment. Some of these filters are rectangular and similar in shape to the combustion air filter. Others are uniquely shaped to fit the available space of particular vehicles' outside-air intakes. Being a relatively recent addition to automobile equipment, this filter is often overlooked [1], and can greatly reduce the effectiveness of the vehicles air conditioning and heating performance. Clogged or dirty cabin air filters can significantly reduce airflow from the cabin vents, as well as introduce allergens into the cabin air stream. The poor performance of these filters is obscured by manufacturers by not using the MERV (minimum efficiency reporting value) rating system. Some people mistakenly believe that some of these are HEPA filters.
2.2.1 MERV
Minimum efficiency reporting value, commonly known as MERV rating is a measurement scale designed in 1987 by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to rate the effectiveness of air filters. The scale "represents a quantum leap in the precision and accuracy of air-cleaner ratings"[2] and allows for improved health, reduced cost and energy efficiency in heating, ventilation and air conditioning (HVAC) design. For example, a HEPA filter is often impractical in central HVAC systems due to the large pressure drop the dense filter material causes. Experiments indicate that less obstructive, medium-efficiency filters of MERV 7 to 13 are almost as effective as true HEPA filters at removing allergens, with much lower associated system and operating costs.[3]
The scale is designed to represent the worst case performance of a filter when dealing with particles in the range of 0.3 to 10 micrometres. The MERV rating is from 1 to 16. Higher MERV ratings correspond to a greater percentage of particles captured on each pass, with a MERV 16 filter capturing more than 95% of particles over the full range.
MERV
Min. particle size
Typical controlled contaminant [2]
Typical Application [2]
17-20[4]
< 0.3 μm
Virus, carbon dust, sea salt, smoke
Electronics & pharmaceutical manufacturing cleanroom
13-16
0.3-1.0 μm
Bacteria, droplet nuclei (sneeze), cooking oil, most smoke and insecticide dust, most face powder, most paint pigments
hospital & general surgery
9-12
1.0-3.0 μm
Legionella, Humidifier dust, Lead dust, Milled flour, Auto emission particulates, Nebulizer droplets
Superior residential, better commercial, hospital laboratories
5-8[5]
3.0-10.0 μm
Mold, spores, dust mite debris, cat and dog dander, hair spray, fabric protector, dusting aids, pudding mix
Better residential, general commercial, industrial workspaces
1-4
> 10.0 μm
Pollen, dust mites, cockroach debris, sanding dust, spray paint dust, textile fibers, carpet fibers
Residential window AC units
While the smallest MERV value in each row has no minimum requirement for filtering that row's particle size, it does have stricter requirements for all larger particle sizes than any smaller MERV value. For example, MERV 13 the "0.3-1.0 μm" row has no minimum requirement for removing 0.3-1.0 μm particles (the standard specifies "<75%") but has higher minimum removal percentages of 1.0-3.0 μm, 3.0-10.0 μm, and > 10 μm particles than MERV 12 and all smaller MERV values. All other MERV values on each row do have minimum removal percentages for that row's particle size.[3].
2.2.2 Internal combustion air filters:
The combustion air filter prevents abrasive particulate matter from entering the engine's cylinders, where it would cause mechanical wear and oil contamination. Most fuel injected vehicles use a pleated paper filter element in the form of a flat panel. This filter is usually placed inside a plastic box connected to the throttle body with ductwork. Older vehicles that use carburetors or throttle body fuel injection typically use a cylindrical air filter, usually a few inches high and between 6 inches (150 mm) and 16 inches (410 mm) in diameter. This is positioned above the carburetor or throttle body, usually in a metal or plastic container which may incorporate ducting to provide cool and/or warm inlet air, and secured with a metal or plastic lid.
2.2.2.1 Long Life Filtration System:
In 2003 Ford Motor Company introduced the Visteon Long Life Filtration System to the Ford Focus. [1] Visteon Corp This system has a foam filter placed in the bumper of the car and is stated to have a 150,000-mile (240,000 km) service interval.[1] According to a technical paper published by Society of Automotive Engineers, this design offers higher and more stable filtration efficiency than conventional air filters.[1]
2.2.2.2 Filter paper:
Pleated paper filter elements are the nearly exclusive choice for automobile engine air cleaners, because they are efficient, easy to service, and cost-effective. The "paper" term is somewhat misleading, as the filter media are considerably different from papers used for writing or packaging, etc. There is a persistent belief amongst tuners, fomented by advertising for aftermarket non-paper replacement filters, that paper filters flow poorly and thus restrict engine performance. In fact, as long as a pleated-paper filter is sized appropriately for the airflow volumes encountered in a particular application, such filters present only trivial restriction to flow until the filter has become significantly clogged with dirt. Construction equipment engines also use this.
2.2.2.3 Foam:
Oil-wetted polyurethane foam elements are used in some aftermarket replacement automobile air filters. Foam was in the past widely used in air cleaners on small engines on lawnmowers and other power equipment, but automotive-type paper filter elements have largely supplanted oil-wetted foam in these applications. Depending on the grade and thickness of foam employed, an oil-wetted foam filter element can offer minimal airflow restriction or very high dirt capacity, the latter property making foam filters a popular choice in off-road rallying and other motorsport applications where high levels of dust will be encountered.
2.2.2.4 Cotton:
Oiled cotton gauze is employed in a growing number of aftermarket automotive air filters marketed as high-performance items. In the past, cotton gauze saw limited use in original-equipment automotive air filters. However, since the introduction of the Abarth SS versions, the Fiat subsidiary supplies cotton gauze air filters as OE filters.
2.2.2.5 Oil Bath:
An oil bath air cleaner consists of a sump containing a pool of oil, and an insert which is filled with fibre, mesh, foam, or another coarse filter media. When the cleaner is assembled, the media-containing body of the insert sits a short distance above the surface of the oil pool. The rim of the insert overlaps the rim of the sump. This arrangement forms a labyrinthine path through which the air must travel in a series of U-turns: up through the gap between the rims of the insert and the sump, down through the gap between the outer wall of the insert and the inner wall of the sump, and up through the filter media in the body of the insert. This U-turn takes the air at high velocity across the surface of the oil pool. Larger and heavier dust and dirt particles in the air cannot make the turn due to their inertia, so they fall into the oil and settle to the bottom of the base bowl. Lighter and smaller particles are trapped by the filtration media in the insert, which is wetted by oil droplets aspirated there into by normal airflow.
Oil bath air cleaners were very widely used in automotive and small engine applications until the widespread industry adoption of the paper filter in the early 1960s. Such cleaners are still used in off-road equipment where very high levels of dust are encountered, for oil bath air cleaners can sequester a great deal of dirt relative to their overall size without loss of filtration efficiency or airflow. However, the liquid oil makes cleaning and servicing such air cleaners messy and inconvenient, they must be relatively large to avoid excessive restriction at high airflow rates, and they tend to increase exhaust emissions of unburned hydrocarbons due to oil aspiration when used on spark-ignition engines
2.2.3 Filter classes:
European Normalisation standards recognise the following filter classes: [6]
This table shows the filters divided by different factors such as the Particulate size blocking, Performance etc.
Usage
Class
Performance
Performance test
Particulate size
approaching 100% retention
Test Standard
Primary filters
G1
65%
Average value
>5 µm
BS EN779
G2
65-80%
Average value
>5 µm
BS EN779
G3
80-90%
Average value
>5 µm
BS EN779
G4
90%-
Average value
>5 µm
BS EN779
Secondary filters
F5
40-60%
Average value
>5 µm
BS EN779
F6
60-80%
Average value
>2 µm
BS EN779
F7
80-90%
Average value
>2 µm
BS EN779
F8
90-95%
Average value
>1 µm
BS EN779
F9
95%-
Average value
>1 µm
BS EN779
Semi Hepa
H10
85%
Minimum value
>1 µm
BS EN1822
H11
95%
Minimum value
>0.5 µm
BS EN1822
H12
99.5%
Minimum value
>0.5 µm
BS EN1822
Hepa
H13
99.95%
Minimum value
>0.3 µm
BS EN1822
H14
99.995%
Minimum value
>0.3 µm
BS EN1822
2.3 The Filter Paper:
The filter paper that is used in the paper air filters is manufactured in different types, and for different purposes, the following will a list of all the uses of this paper and the versatility of its use. Filter paper is a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solids from liquids or air.
2.3.1 Properties:
Filter paper comes in various porosities and grades depending on the applications it is meant for. The important parameters are wet strength, porosity, particle retention, flow rate, compatibility, efficiency and capacity.
There are two mechanisms of filtration with paper; volume and surface. By volume filtration the particles are caught in the bulk of the filter paper. By surface filtration the particles are caught on the paper surface.
2.3.2 Manufacture:
The raw materials are different paper pulps. The pulp may be from softwood, hardwood, fibre crops, and mineral fibres. For high quality filters, dissolving pulp and mercerised pulp are used. Most filter papers are made on small paper machines. For laboratory filters the machines may be as small as 50 cm width. The paper is often creped to improve porosity. The filter papers may also be treated with reagents or impregnation to get the right properties.
2.3.3 Use in Air Filter:
The main application for air filters are combustion air to engines. The filter papers are transformed into filter cartridges, which then are fitted to a holder. The construction of the cartridges mostly requires that the paper is stiff enough to be self supporting. A paper for air filters needs to be very porous and have a weight of 100 - 200 g/m2. Normally particularly long fibrous pulp that is mercerised is used to get these properties. The paper is normally impregnated to improve the resistance to moisture. [7] Some heavy duty qualities are made to be rinsed and thereby extend the life of the filter.
2.3.4 Use in Fuel Filter:
The paper used for fuel filters is a crêped paper with controlled porosity, which is pleated and wound to cartridges. The raw material for filter paper used in fuel filters are made of a mixture of hardwood and softwood fibres. The basis weight of the paper is 50 - 80 g/m2. [7]
2.3.5 Use in Laboratory Filter:
For laboratory use filter papers are made in varieties of ways since specific applications require specific types of papers. The raw materials might be acid washed wooden fibers, carbon or quartz fibres. Finishing and confectioning is the bulk of the production work. [7]
In laboratories, filter paper is usually used with a filter funnel, Hirsch, or Buchner funnel.
Ash less filter paper is mainly used for gravimetric methods in quantitative chemical analysis. It has a base weight of 80 g/m2.
These papers may be impregnated with various reagents for use in detection tests like pH, pregnancy or diabetes. [7]
2.3.6 Use in Oil Filters:
Engine oil is filtered to remove impurities. Filtration of oil is normally done with volume filtration. Filter papers for lubrication oils are impregnated to resist high temperatures. [7]
2.4 Oil Filter:
Just like the Air Filter is important for the vehicle so is the Oil Filter, this section will just focus on the basic concept relating to the oil filter, its importance and the manufacturing method, uses etc. An oil filter is a filter designed to remove contaminants from engine oil, transmission oil, lubricating oil, or hydraulic oil. Oil filters are used in many different types of hydraulic machinery. A chief use of the oil filter is in internal-combustion engines in on- and off-road motor vehicles, light aircraft, and various naval vessels. Other vehicle hydraulic systems, such as those in automatic transmissions and power steering, are often equipped with an oil filter. Gas turbine engines, such as those on jet aircraft, require the use of oil filters. Aside from these uses, oil production, transport, and recycling facilities also employ filters in the manufacturing process. Early automobile engines did not use oil filters. For this reason, along with the generally low quality of oil available, very frequent oil changes were required. The first oil filters were simple, generally consisting of a screen placed at the oil pump intake. In 1923, American inventors Ernest Sweetland and George H. Greenhalgh devised an automotive oil filter and called it the Purolator, a portmanteau of "pure oil later". This was a bypass filter: most of the oil flowed directly from the oil pan to the engine's working parts, and a smaller proportion of the oil was sent through the filter via a second flow path in parallel with the first. The oil was thus filtered over time. Modern bypass oil filter systems for diesel engines are becoming popular in consumer applications, but have been in commercial use for some time due to potential reduction in maintenance costs. Oil filters are generally located near the middle or bottom of the engine. Most pressurized lubrication systems incorporate an overpressure relief valve to allow oil to bypass the filter if its flow restriction is excessive, to protect the engine from oil starvation. Filter bypass may occur if the filter is clogged or the oil is thickened by cold weather. The overpressure relief valve is frequently incorporated into the oil filter. Filters mounted such that oil tends to drain from them usually incorporate an anti-drainback valve to hold oil in the filter after the engine (or other lubrication system) is shut down. This is done to avoid a delay in oil pressure buildup once the system is restarted; without an anti-drainback valve, pressurized oil would have to fill the filter before travelling onward to the engine's working parts. This situation can cause premature wear of moving parts due to initial lack of oil. [8][9][10][11]
Types of Oil Filters:
2.4.1 Mechanical:
Mechanical designs employ an element made of bulk material (such as cotton waste) or pleated Filter paper to entrap and sequester suspended contaminants. As material builds up on (or in) the filtration medium, oil flow is progressively restricted. This requires periodic replacement of the filter element (or the entire filter, if the element is not separately replaceable).
2.4.2 Cartridge and spin-on:
Early engine oil filters were of cartridge (or replaceable element) construction, in which a permanent housing contains a replaceable filter element or cartridge. The housing is mounted either directly on the engine or remotely with supply and return pipes connecting it to the engine. In the mid-1950s, the spin-on oil filter design was introduced: a self-contained housing and element assembly which was to be unscrewed from its mount, discarded, and replaced with a new one. This made filter changes more convenient and potentially less messy, and quickly came to be the dominant type of oil filter installed by the world's automakers. Conversion kits were offered for vehicles originally equipped with cartridge-type filters. [12] In the 1990s, European and Asian automakers in particular began to shift back in favour of replaceable-element filter construction, because it generates less waste with each filter change. American automakers have likewise begun to shift to replaceable-cartridge filters, and retrofit kits to convert from spin-on to cartridge-type filters are offered for popular applications. [13] Commercially available automotive oil filters vary in their design, materials, and construction details. These variables affect the efficacy, durability, and cost of the filter. [14]
2.4.3 Magnetic:
Magnetic filters use a permanent magnet or an electromagnet to capture ferromagnetic particles. An advantage of magnetic filtration is that maintaining the filter simply requires cleaning the particles from the surface of the magnet. [15] Automatic transmissions in vehicles frequently have a magnet in the fluid pan to sequester magnetic particles and prolong the life of the media-type fluid filter. Some companies are manufacturing magnets that attach to the outside of an oil filter or magnetic drain plugs -- first invented and offered for cars and motorcycles in the mid-1930s[16] -- to aid in capturing these metallic particles, though there is ongoing debate as to the effectiveness of such devices.[17]
2.4.4 Centrifugal:
A centrifugal oil cleaner is a rotary sedimentation device using centrifugal force rather than gravity to separate contaminants from the oil, in the same manner as any other centrifuge. Pressurized oil enters the center of the housing and passes into a drum rotor free to spin on a bearing and seal. The rotor has two jet nozzles arranged to direct a stream of oil at the inner housing to rotate the drum. The oil then slides to the bottom of the housing wall, leaving particulate oil contaminants stuck to the housing walls. The housing must periodically be cleaned, or the particles will accumulate to such a thickness as to stop the drum rotating. In this condition, unfiltered oil will be recirculated.
2.4.5 High Efficiency:
High efficiency oil filters are a type of bypass filter that are claimed to allow extended oil drain intervals.[11] HE oil filters typically have pore sizes of 3 micrometres, which studies have shown reduce engine wear.[18] Some fleets have been able to increase their drain intervals up to 5-10 times.[19]
2.4.6 Filter placement in an oil system:
Deciding how clean the oil needs to be is important as cost increases rapidly with cleanliness. Having determined the optimum target cleanliness level for a contamination control programme, many engineers are then challenged by the process of optimizing the location of the filter. To ensure effective solid particle ingression balance, the engineer must consider various elements such as whether the filter will be for protection or for contamination control, ease of access for maintenance, and the performance of the unit being considered to meet the challenges of the target set. [20]
Chapter 3:
Research Methodology:
In this section, we discuss about the research that was done regarding the different aspects of the project to be applied.
3.1 Particulates:
Atmospheric particulate matter - also known as particulates or particulate matter (PM) - are tiny pieces of solid or liquid matter associated with the Earth's atmosphere. They are suspended in the atmosphere as atmospheric aerosol, a term which refers to the particulate/air mixture, as opposed to the particulate matter alone. However, it is common to use the term aerosol to refer to the particulate component alone. Sources of particulate matter can be manmade or natural. They can adversely affect human health and also have impacts on climate and precipitation. Subtypes of atmospheric particle matter include suspended particulate matter (SPM), respirable suspended particle (RSP; particles with diameter of 10 micrometres or less), fine particles, and soot. [20]
3.1.1 Sources of atmospheric particulate matter:
Some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray. Human activities, such as the burning of fossil fuels in vehicles, power plants and various industrial processes also generate significant amounts of particulates. Coal combustion in developing countries is the primary method for heating homes and supplying energy. Because salt spray over the oceans is the overwhelmingly most common form of particulate in the atmosphere, anthropogenic aerosol, those made by human activities currently account for about 10 percent of the total mass of aerosols in our atmosphere. [21]
http://upload.wikimedia.org/wikipedia/commons/4/47/Airborne-particulate-size-chart.jpg
Figure 1: Particulate Distribution
This diagram shows the size distribution in micrometres of various types of atmospheric particulate matter. It also shows the different types of particulates in the atmosphere [20]
3.1.2 Composition:
The composition of aerosols and particles depends on their source. Wind-blown mineral dust [22] tends to be made of mineral oxides and other material blown from the Earth's crust; this particulate is light-absorbing. Sea salt [23] is considered the second-largest contributor in the global aerosol budget, and consists mainly of sodium chloride originated from sea spray; other constituents of atmospheric sea salt reflect the composition of sea water, and thus include magnesium, sulfate, calcium, potassium, etc. In addition, sea spray aerosols may contain organic compounds, which influence their chemistry. Sea salt does not absorb light.
Secondary particles derive from the oxidation of primary gases such as sulfur and nitrogen oxides into sulfuric acid (liquid) and nitric acid (gaseous). The precursors for these aerosols-i.e. the gases from which they originate-may have an anthropogenic origin (from fossil fuel or coal combustion) and a natural biogenic origin. In the presence of ammonia, secondary aerosols often take the form of ammonium salts; i.e. ammonium sulfate and ammonium nitrate (both can be dry or in aqueous solution); in the absence of ammonia, secondary compounds take an acidic form as sulfuric acid (liquid aerosol droplets) and nitric acid (atmospheric gas). Secondary sulfate and nitrate aerosols are strong light-scatterers. [24] This is mainly because the presence of sulfate and nitrate causes the aerosols to increase to a size that scatters light effectively.
Organic matter (OM) can be either primary or secondary, the latter part deriving from the oxidation of VOCs; organic material in the atmosphere may either be biogenic or anthropogenic. Organic matter influences the atmospheric radiation field by both scattering and absorption. Another important aerosol type is constitute of elemental carbon (EC, also known as black carbon, BC): this aerosol type includes strongly light-absorbing material and is thought to yield large positive radiative forcing. Organic matter and elemental carbon together constitute the carbonaceous fraction of aerosols. [25] Secondary organic aerosols, tiny "tar balls" resulting from combustion products of internal combustion engines, have been identified as a danger to health. [26]
The chemical composition of the aerosol directly affects how it interacts with solar radiation. The chemical constituents within the aerosol change the overall refractive index. The refractive index will determine how much light is scattered and absorbed.
The composition of particulate matter that generally causes visual effects such as smog consists of sulphur dioxide, nitrogen oxides, carbon monoxide, mineral dust, organic matter, and elemental carbon also known as black carbon or soot. The particles are hydroscopic due to the presence of sulphur, and SO2 is converted to sulphate when high humidity and low temperatures are present. This causes the reduced visibility and yellow colour. [27]
3.1.3 Deposition processes:
In general, the smaller and lighter a particle is, the longer it will stay in the air. Larger particles (greater than 10 micrometers in diameter) tend to settle to the ground by gravity in a matter of hours whereas the smallest particles (less than 1 micrometer) can stay in the atmosphere for weeks and are mostly removed by precipitation. Diesel particulate matter is highest near the source of emission. Any info regarding DPM and the atmosphere, flora, height, and distance from major sources would be useful to determine health effects.
3.1.4 Control technologies:
Particulate matter emissions are highly regulated in most industrialized countries. Due to environmental concerns, most industries are required to operate some kind of dust collection system to control particulate emissions. These systems include inertial collectors (cyclone collectors), fabric filter collectors (baghouses), wet scrubbers, and electrostatic precipitators.
Cyclone collectors are useful for removing large, coarse particles and are often employed as a first step or "pre-cleaner" to other more efficient collectors. Fabric filters or baghouses are the most commonly employed in general industry. They work by forcing dust laden air through a bag shaped fabric filter leaving the particulate to collect on the outer surface of the bag and allowing the now clean air to pass through to either be exhausted into the atmosphere or in some cases recirculated into the facility. Common fabrics include polyester and fiberglass and common fabric coatings include PTFE (commonly known as Teflon©). The excess dust buildup is then cleaned from the bags and removed from the collector. Wet scrubbers pass the dirty air through a scrubbing solution (usually a mixture of water and other compounds) allowing the particulate to attach to the liquid molecules. Electrostatic precipitators electrically charge the dirty air as it passes through. The now charged air then passes by large electromagnetic plates which attract the charged particle in the airstream collecting them and leaving the now clean air to be exhausted or recirculated. [28]
3.1.5 Climate effects:
Atmospheric aerosols affect the climate of the earth by changing the amount of incoming solar radiation and outgoing terrestrial long wave radiation retained in the earth's system. This occurs through several distinct mechanisms which are split into direct, indirect [29] [30] and semi-direct aerosol effects. The aerosol climate effects are the biggest source of uncertainty in future climate predictions.[31] The Intergovernmental Panel on Climate Change, Third Assessment Report, says: While the radiative forcing due to greenhouse gases may be determined to a reasonably high degree of accuracy. The uncertainties relating to aerosol radiative forcings remain large, and rely to a large extent on the estimates from global modelling studies that are difficult to verify at the present time. [32]
3.1.5.1 Direct effect:
The Direct aerosol effect consists of any direct interaction of radiation with atmospheric aerosol, such as absorption or scattering. It affects both short and longwave radiation to produce a net negative radiative forcing. [33] The magnitude of the resultant radiative forcing due to the direct effect of an aerosol is dependent on the albedo of the underlying surface, as this affects the net amount of radiation absorbed or scattered to space. e.g. if a highly scattering aerosol is above a surface of low albedo it has a greater radiative forcing than if it was above a surface of high albedo. The converse is true of absorbing aerosol, with the greatest radiative forcing arising from a highly absorbing aerosol over a surface of high albedo. [29] The Direct aerosol effect is a first order effect and is therefore classified as a radiative forcing by the IPCC. [31] The interaction of an aerosol with radiation is quantified by the Single Scattering Albedo (SSA), the ratio of scattering alone to scattering plus absorption (extinction) of radiation by a particle. The SSA tends to unity if scattering dominates, with relatively little absorption, and decreases as absorption increases, becoming zero for infinite absorption. For example, sea-salt aerosol has an SSA of 1, as a sea-salt particle only scatters, whereas soot has an SSA of 0.23, showing that it is a major atmospheric aerosol absorber.
3.1.5.2 Indirect effect:
The Indirect aerosol effect consists of any change to the earth's radiative budget due to the modification of clouds by atmospheric aerosols, and consists of several distinct effects. Cloud droplets form onto pre-existing aerosol particles, known as cloud condensation nuclei (CCN).
For any given meteorological conditions, an increase in CCN leads to an increase in the number of cloud droplets. This leads to more scattering of shortwave radiation i.e. an increase in the albedo of the cloud, known as the Cloud albedo effect, First indirect effect or Twomey effect.[30] Evidence supporting the cloud albedo effect has been observed from the effects of ship exhaust plumes[34] and biomass burning [35] on cloud albedo compared to ambient clouds. The Cloud albedo aerosol effect is a first order effect and is therefore is classified as a radiative forcing by the IPCC. [31]
An increase in cloud droplet number due to the introduction of aerosol acts to reduce the cloud droplet size, as the same amount of water is divided between more droplets. This has the effect of suppressing precipitation, increasing the cloud lifetime, known as the cloud lifetime aerosol effect, second indirect effect or Albrecht effect.[31] This is been observed as the suppression of drizzle in ship exhaust plume compared to ambient clouds,[36] and inhibited precipitation in biomass burning plumes.[37] This cloud lifetime effect is classified as a climate feedback (rather than a radiative forcing) by the IPCC due to the interdependence between it and the hydrological cycle.[31] However, it has previously been classified as a negative radiative forcing.[38]
3.1.5.3 Semi-Direct effect:
The Semi-direct effect concerns any radiative effect of caused by absorbing atmospheric aerosol such as soot, apart from direct scattering and absorption, which is classified as the direct effect. It encompasses many individual mechanisms, and in general is more poorly defined and understood than the direct and indirect aerosol effects. For instance, if absorbing aerosols are present in a layer aloft in the atmosphere, they can heat surrounding air which inhibits the condensation of water vapour, resulting in less cloud formation. [39] Additionally, heating a layer of the atmosphere relative to the surface results in a more stable atmosphere due to the inhibition of atmospheric convection. This inhibits the convective uplift of moisture, [40] which in turn reduces cloud formation. The heating of the atmosphere aloft also leads to a cooling of the surface, resulting in less evaporation of surface water. The effects described here all lead to a reduction in cloud cover i.e. an increase in planetary albedo. The semi-direct effect classified as a climate feedback) by the IPCC due to the interdependence between it and the hydrological cycle. [31] However, it has previously been classified as a negative radiative forcing.[38].
3.2 Health effects of particulates:
Increased levels of fine particles in the air as a result of anthropogenic particulate air pollution "is consistently and independently related to the most serious effects, including lung cancer and other cardiopulmonary mortality."[41] The large number of deaths [42] and other health problems associated with particulate pollution was first demonstrated in the early 1970s [43] and has been reproduced many times since. PM pollution is estimated to cause 22,000-52,000 deaths per year in the United States (from 2000) [44] and 200,000 deaths per year in Europe[citation needed].
The effects of inhaling particulate matter that have been widely studied in humans and animals now include asthma, lung cancer, cardiovascular issues, respiratory diseases, birth defects, and premature death. The size of the particle is a main determinant of where in the respiratory tract the particle will come to rest when inhaled. Because of their small size, particles on the order of ~10 micrometers or less (PM10) can penetrate the deepest part of the lungs such as the bronchioles or alveoli. [45] Larger particles are generally filtered in the nose and throat via cilia and mucus, but particulate matter smaller than about 10 micrometers, referred to as PM10, can settle in the bronchi and lungs and cause health problems. The 10 micrometer size does not represent a strict boundary between respirable and non-respirable particles, but has been agreed upon for monitoring of airborne particulate matter by most regulatory agencies. Similarly, particles smaller than 2.5 micrometers, PM2.5, tend to penetrate into the gas exchange regions of the lung, and very small particles (< 100 nanometers) may pass through the lungs to affect other organs. Penetration of particles in not wholly dependent on their size; shape and chemical composition also play a part. Therefore simple nomenclature can be used to distinguish between the relative penetrations of a PM particle into the cardiovascular system. Inhalable particles penetrate no further than the bronchi as they are filtered out by the cilia, Thoracic particles can penetrate right into terminal bronchioles whereas PM which can penetrate to alveoli and hence the circulatory system are termed Respirable particles. A study published in the Journal of the American Medical Association indicates that PM2.5 leads to high plaque deposits in arteries, causing vascular inflammation and atherosclerosis - a hardening of the arteries that reduces elasticity, which can lead to heart attacks and other cardiovascular problems.[46] The World Health Organization (WHO) estimates that "... fine particulate air pollution (PM(2.5)), causes about 3% of mortality from cardiopulmonary disease, about 5% of mortality from cancer of the trachea, bronchus, and lung, and about 1% of mortality from acute respiratory infections in children under 5 yr, worldwide." PMID 16024504. Researchers suggest that even short-term exposure at elevated concentrations could significantly contribute to heart disease. A study in The Lancet concluded that traffic exhaust is the single most serious preventable cause of heart attack in the general public, the cause of 7.4% of all attacks. [47]
The smallest particles, less than 100 nanometers (nanoparticles), may be even more damaging to the cardiovascular system. [48]
There is evidence that particle smaller than 100 nanometers can pass through cell membranes and migrate into other organs, including the brain. It has been suggested that particulate matter can cause similar brain damage as that found in Alzheimer patients. Particles emitted from modern diesel engines (commonly referred to as Diesel Particulate Matter, or DPM) are typically in the size range of 100 nanometers (0.1 micrometer). In addition, these soot particles also carry carcinogenic components like benzopyrenes adsorbed on their surface. It is becoming increasingly clear that the legislative limits for engines, which are in terms of emitted mass, are not a proper measure of the health hazard. One particle of 10 µm diameter has approximately the same mass as 1 million particles of 100 nm diameter, but it is clearly much less hazardous, as it probably never enters the human body - and if it does, it is quickly removed. Proposals for new regulations exist in some countries, with suggestions to limit the particle surface area or the particle number.
A further complexity that is not entirely documented is how the shape of PM can affect health. Of course the dangerous feathery shape of asbestos is widely recognised to lodge itself in the lungs with often dire consequences. Geometrically angular shapes have more surface area than rounder shapes, which in turn affects the binding capacity of the particle to other, possibly more dangerous substances.
The inhalable dust fraction is the fraction of dust that enters the nose and mouth and may be deposited anywhere in the respiratory tract. The thoracic fraction is the fraction that enters the thorax and is deposited within the lung airways and the gas-exchange regions. The respiratory fraction is what is deposited in the gas exchange regions (alveoli). [49]
The site and extent of absorption of inhaled gases and vapors are determined by their solubility in water. Absorption is also dependent upon air flow rates and the partial pressure of the gases in the inspired air. The fate of a specific contaminant is dependent upon the form in which it exists (aerosol or particulate). Inhalation also depends upon the breathing rate of the subject. [50]
Researchers at the Johns Hopkins Bloomberg School of Public Health have conducted the largest nationwide study on the acute health effects of coarse particle pollution. Coarse particles are airborne pollutants that fall between 2.5 and 10 micrometers in diameter.[51] The study, published in the May 14, 2008, edition of JAMA, found evidence of an association with hospital admissions for cardiovascular diseases but no evidence of an association with the number of hospital admissions for respiratory diseases. After taking into account fine particle levels, the association with coarse particles remained but was no longer statistically significant.
Particulate matter studies in Bangkok Thailand indicated a 1.9% increased risk of dying from cardiovascular disease, and 1.0% risk of all disease for every 10 micrograms per cubic meter. Levels averaged 65 in 1996, 68 in 2002, and 52 in 2004. Decreasing levels may be attributed to conversions of diesel to natural gas combustion as well as improved regulations.[52]
The Mongolian government agency has recorded a 45% increase in the rate of respiratory illness in the past five years. Bronchial asthma, chronic obstructive pulmonary disease and interstitial pneumonia are the most common ailments treated by area hospitals. Levels of premature death, chronic bronchitis, and cardiovascular disease are increasing at a rapid rate. [27]
3.2.1 Effect on vegetation:
Particulate matter can clog stomata openings of plants and interfere with photosynthesis functions. In this manner high particulate matter concentrations in the atmosphere can lead to growth stunting or mortality in some plant species. [53]
3.3 Regulation:
Due to the health effects of particulate matter, various governments have created regulations both for the emissions allowed from certain types of pollution sources (motor vehicles, industrial emissions etc.) and for the ambient concentration of particulates. Many urban areas in the U.S. and Europe still frequently violate the particulate standards, though urban air on these continents has become cleaner, on average, with respect to particulates over the last quarter of the 20th century. Much of the developing world, especially Asia, exceeds standards by such a wide margin that even brief visits to these places may be unhealthy.
3.3.1 EU legislation:
In directives 1999/30/EC and 96/62/EC, the European Commission has set limits for PM10 in the air:
Phase 1
from 1 January 2005
Phase 2¹
from 1 January 2010
Yearly average
40 µg/m³
20 µg/m³
Daily average (24-hour)
allowed number of exceedences per year.
50 µg/m³
35
50 µg/m³
7
3.3.2 Canada:
In Canada the standard for particulate matter is set nationally by the federal-provincial Canadian Council of Ministers of the Environment (CCME). Jurisdictions (provinces) may set more stringent standards. The CCME standard for particulate matter is 30 μg/m3 (daily average, i.e. 24-hour period, 3 year average, 98th percentile). [54]
3.4 Environmental Standards Saudi Arabia:
These environmental standards have been taken from the government official document. Since the focus was on Middle East, this is the chosen country as an example of research.
The following part of the document is the official government document and has been taken from reference [55] is cited as the Standard for Control of Emissions from Mobile Sources. This standard revises the current General Standards for the Environment (specifically document number 1409-01) issued by the Presidency of Meteorology and Environment (PME). The effective date of this standard is 01/05/1433H corresponds to 24/03/2012G.
Preliminary:
3.4.1 Definitions:
'Competent Agency' Refers to the Presidency of Meteorology and Environment (PME), previously the Meteorology and Environmental Protection Administration (MEPA);
'emission-related maintenance' refers to maintenance that substantially affects emissions or is likely to substantially affect emission deterioration;
'GER' Refers to the General Environmental regulation;
'KSA' Refers to the Kingdom of Saudi Arabia;
'Level' shall mean the concentration of a pollutant in ambient air or the deposition thereof on surfaces in a given time;
'Large sites' shall refer to those sites that have 5 or more engines, equipment and/or vehicles that have the potential to be operational at the same time;
'Limit value' shall mean a level fixed on the basis of scientific knowledge, with the aim of avoiding, preventing or reducing harmful effects on human health and/or the environment as a whole, to be attained within a given period and not to be exceeded once attained;
'Normal cubic metre (Nm3)' means that volume of dry gas which occupies a cubic metre at a temperature of zero degrees Celsius and at an absolute pressure equivalent to one atmosphere;
'oxides of nitrogen' shall mean the sum of nitric oxide and nitrogen dioxide added as particles per billion and expressed as nitrogen dioxide in micrograms per cubic meter;
'PM2.5' is particulate matter with an aerodynamic diameter of up to 2.5 µm, referred to as the fine particle fraction;
'PM10' is particulate matter with an aerodynamic diameter of up to 10 µm, the fine and coarse particle fractions combined;
'PME' Refers to the Presidency of Meteorology and Environment who are designated as the responsible authority for the protection of the environment andthe development of environmental protection standards in the Kingdom of Saudi Arabia;
'Pollutant' shall mean any substance introduced directly or indirectly by man into the ambient air and likely to have harmful effects on human health and/or the environment as a whole.
3.4.2 Purpose:
a) The objective of this standard is to set the framework and activities required to enable sustainable management of mobile source emissions within the Kingdom of Saudi Arabia.
b) This standard introduces emission limits for individual pieces of equipment used outdoors and aims to protect, maintain and improve the Kingdom's quality of life, human health, occupational health and natural ecosystems including croplands, forests and deserts whilst maintaining appropriate economic and social development.
c) The Competent Agency shall liaise with relevant bodies responsible for the protection of nationally and internationally designated sites and species to ensure that mobile source emission standards are appropriate to maintain and improve air quality.
3.4.3Scope:
a) This standard refers to air emissions from non-road engines, equipment and vehicles. This includes sources such as mobile generators, agricultural machinery and large earth-moving equipment. b) This standard includes emission limits for diesel (compression-ignition) engines, small and large petrol (spark-ignition) engines, and other recreational vehicles not included in SASO standards.
c) This standard does not include emissions from road vehicles, marine vessels, locomotives, and aircrafts
d) This standard sets out emission limit values depending on engine type and capacity.
3.4.4 Exemptions:
a) Exemptions may be applied in circumstances where the enforcement of this standard impracticable or inappropriate.
b) Exemption may be made for the activities specified in, but not restricted to table 1. Only the Competent Agency will determine where these exemptions apply and which, if any, activities beyond this list are included.
Figure 2: Exempt Activities
3.4.5 Powers of authority:
a) Within the scope of these standards the Competent Agency may:
i) Prescribe specific requirements as to the concentrations of contaminants within emissions originating from non-road mobile sources within the Kingdom;
ii) Prescribe specific requirements as to other characteristics of non-road mobile source emissions; and
iii) Authorise a locally designated authority to exercise any power conferred by regulations made by virtue of paragraphs
(i) - (iii) above.
b) The Competent Agency may for the purposes of these Standards appoint persons to act on their behalf as technical assessors and monitors in relation to the powers and duties conferred on him by these standards and/or subsequent amendments.
c) In addition to the powers conferred by other sections contained within these standards, it shall be the duty of a relevant party;
i) To give the Competent Agency all such assistance; and
ii) Provide the Competent Agency with all such information, as may reasonably be required for the purpose of carrying out an investigation.
d) Any Competent Agency, for the purpose of Mobile source air quality regulation may;
i) Enter any site or premises for the purpose of carrying out any such investigation;
ii) Carry out such inspections, measurements and tests on engines, equipment or vehicles as that person considers appropriate for the purpose of enabling him to carry out any such investigation; or
iii) At any reasonable time require any relevant party to supply him with copies of, or of extracts from, the contents of any records kept for the purpose of complying with mobile source emission standards.
3.4.6 Enforcement procedures:
a) Failure to comply with the requirements of these standards may lead to prosecution by the Competent Agency and those convicted of such failure may be subject to fines or periods of imprisonment as laid out in the General Environmental Regulations.
b) It is anticipated that the requirements of this standard will be enforced nationally with inspections taking place to verify their implementation at a regional and local level.
3.4.7 Penalty fines:
a) Maximum fines that may be imposed for exceeding the applicable standard, breach of permit and failure to comply with an abatement notice are set out in the General Environmental Regulations.
3.4.8 Appeals:
a) A right of appeal exists for any organisation or individual who is required to take action as a consequence of the implementation of the revised standard.
b) The right of appeal against conviction or sentence is available through the appropriate judicial system as set out in the General Environmental Regulations.
c) All appeals should be fully supported with a documented case containing as a minimum, the information required under the appeals process of the General Environmental Regulations.
3.4.9 Periodic Review:
a) There may be some requirement at a future date to adjust the standards included to recognise specific local conditions and or improved understanding of the effects of mobile source air emissions.
b) As a minimum, the Competent Agency shall undertake a periodic review of this standard every 5 years.
c) Where new information suggests that adjustments are required to this standard, all changes will be subject to the appropriate consultation and will be notified to facilities by the Competent Agency. Appropriate implementation time will be allowed.
General Provisions:
3.4.10 Units of measurement:
a) Air emission from traffic can be calculated by the use of emission factors usually expressed as emission in g/KW-hr or as a percentage of fuel used.
b) Where numerical values are stated in relation to mobile source air emission standards the units are also present, these may vary according to the parameter referenced.
c) Where an individual substance is prohibited the concentration limit may be specified as undetectable or '0'. In cases where there is no provision within the standard, at this time, for a particular parameter the limit may be specified as N/A.
Mobile source emission criteria:
3.4.11 Prescribed mobile air emission standards:
a) Tables 1, 2 and 3 outline the prescribed mobile air emission standards for:
i) Non-road diesel (compression-injection) engines;
ii) small and large petrol (spark-ignition) engines; and
iii) Non-road recreational vehicles and engines.
b) The standards prescribed in tables apply to all new engines produced after the date of transposition of these standards.
2) General operating conditions
a) The use of non-road engines, equipment and vehicles must not jeopardize achievement of the Kingdom's Ambient Air Quality Standards.
b) Where the Ambient Air Quality Standards are exceeded or a potential exists for them to be exceeded in future as a direct result of the use of non-road engines, equipment or vehicles, operational procedures must be developed to mitigate these impacts.
3.4.12 Emission related maintenance:
a) All owners or operators of non-road engines equipment and vehicles must ensure that they undertake appropriate emission-related maintenance.
b) Emission-related maintenance includes any adjustment, cleaning, repair, or replacement of emission-related components, which include the following:
i) Electronic control units, after treatment devices, fuel-metering components, EGRsystem components, crankcase-ventilation valves, all components related to chargeair compression and cooling, and all sensors and actuators associated with any of these components; and
ii) Any other component whose primary purpose is to reduce emissions.
c) Records of all emission-related maintenance must be held for a period of no less than 5 years.
3.4.13 Specific requirements for large sites:
a) The owner or operator of a large site or facility must develop an internal management program. For the purpose of this standard, large sites are those that have 5 or more engines, equipment and/or vehicles that have the potential to be operational at the same time.
b) This engine emission management programme will include the following:
i) A list of all applicable engines;
ii) Engine maintenance procedures;
iii) Procedures to ensure best available environmental technology are used where economically feasible; and
iv) Potential hazards and emergency response procedures.
c) It is the responsibility of the site owner or his designated site manager to ensure the implementation and maintenance of the engine emission management program;
d) All engine emission management program documentation should be organised carefully and made available to the Competent Agency when required;
e) Failure to submit internal management program documentation to the Competent Agency, within a 30 day period, will be deemed as a failure to comply with the standard.
3.4.14 Abatement notices:
a) Where the Competent Agency identifies activities that pose significant current or potential risk to the environment or human health, it may issue an abatement notice that will detail abatement actions. These may include the termination of activities which must be undertaken to reduce that risk.
b) Activities which are not in contravention of mobile source emission threshold values may still be subject to the conditions of an abatement notice.
c) The requirements of an abatement notice are legally enforceable by the Competent Agency.
3.5 Look at Cyclonic Separation:
Cyclonic separation is a method of removing particulates from an air, gas or liquid stream, without the use of filters, through vortex separation. Rotational effects and gravity are used to separate mixtures of solids and fluids. The method can also be used to separate fine droplets of liquid from a gaseous stream. A high speed rotating (air) flow is established within a cylindrical or conical container called a cyclone. Air flows in a helical pattern, beginning at the top (wide end) of the cyclone and ending at the bottom (narrow) end before exiting the cyclone in a straight stream through the centre of the cyclone and out the top. Larger (denser) particles in the rotating stream have too much inertia to follow the tight curve of the stream, and strike the outside wall, then falling to the bottom of the cyclone where they can be removed. In a conical system, as the rotating flow moves towards the narrow end of the cyclone, the rotational radius of the stream is reduced, thus separating smaller and smaller particles. The cyclone geometry, together with flow rate, defines the cut point of the cyclone. This is the size of particle that will be removed from the stream with 50% efficiency. Particles larger than the cut point will be removed with a greater efficiency and smaller particles with a lower efficiency. An alternative cyclone design uses a secondary air flow within the cyclone to keep the collected particles from striking the walls, to protect them from abrasion. The primary air flow containing the particulates enters from the bottom of the cyclone and is forced into spiral rotation by stationary spinner vanes. The secondary air flow enters from the top of the cyclone and moves downward toward the bottom, intercepting the particulate from the primary air. The secondary air flow also allows the collector to optionally be mounted horizontally, because it pushes the particulate toward the collection area, and does not rely solely on gravity to perform this function. Large scale cyclones are used in sawmills to remove sawdust from extracted air. Cyclones are also used in oil refineries to separate oils and gases, and in the cement industry as components of kiln preheaters. Cyclones are increasingly used in the household, as the core technology in bagless types of portable vacuum cleaners and central vacuum cleaners. Cyclones are also used in industrial and professional kitchen ventilation for separating the grease from the exhaust air in extraction hoods. Smaller cyclones are used to separate airborne particles for analysis. Some are small enough to be worn clipped to clothing, and are used to separate respirable particles for later analysis. Analogous devices for separating particles or solids from liquids are called hydrocyclones or hydroclones. These may be used to separate solid waste from water in wastewater and sewage treatment. [56]
File:Cyclone separator.svg
Figure 3: Cyclonic Separation
3.6 Air Filter Selection:
There are various factors that are taken into consideration, as shown throughout the documentation. But some of the very basic ones are:
3.6.1 Shapes:
If you've looked online for a replacement air filter for your car, you've noticed that there are several different shapes available. The most common shapes of air filters for cars are square, cylindrical and conical. The question you may have is, which one is for your car? The easiest way to determine this is to get under the hood of your car. Most modern cars will have the air filter housed in a box somewhere towards the front of the engine compartment. Look for a box towards the front with a lid you can remove. If you're uncertain, you can refer to your owner's manual. Your owner's manual may have specific information about the type of filter required for your car's engine. If it doesn't, you can look online, or buy a service manual online or from your local auto parts store. Older cars may have a cylindrical style filter mounted over the center of the engine. You'll most often find it housed in a cylindrical container over your engine, held down by a wing nut or some other type of retaining nut. If you have bought your car with aftermarket modifications to your intake system, you may find that there is a conical style air filter located somewhere in your engine compartment. One common type of aftermarket intake system is the cold air intake. With this, you'll most likely find your car's air filter mounted inside a box, similar to the OEM box, in the same location. Once open, you'll find a conical filter within. [57]
3.6.2 Sizes:
Sizing the air filter for your car should be a simply process. Once you've located and removed your car's air filter, it should have markings that indicate its size. Alternatively, you can look online, in your owner's manual or in a service manual, if you own one. For square style filters, fitment is very important. The correct size must be installed in order to ensure that all air entering into the engine is clean. For cylindrical style filters, the most important measurement is the height. The filter again needs to catch all the air entering into the engine. If the cylinder is slightly smaller than you're original, that may be okay, as long as there is a seal at the top of the housing. For the conical style air filters for cars, as long as the filter fits over the intake tube, you should not have any problems. Most conical style intakes come with various inserts that you can use to ensure the proper fit. Another consideration for conical style air filters is that of length. This doesn't make any difference to your engine. The only thing length will determine is proper fitment in the engine compartment, and frequency of cleaning/replacement. Purchase the air filter with the proper length to ensure that it does not come into contact with any moving parts inside your engine compartment. [57]
3.6.3 Material:
There are two common types of materials used in air filters for cars - paper and cotton. There are certainly other types of air filters, but these are the two most common types found in today's automobiles. Both will work in your car's engine, the difference is cost and upkeep. With paper filters, when the filter can no longer be cleaned by hand adequately, they can simply be discarded and replaced for very little cost. With cotton air filters, the cost is much greater, but they can be cleaned and reused indefinitely. There is one catch with cotton air filters, however. In order to clean them properly, you will need to use specialty products, else the cleaning will be ineffective.
