Emission Control System- How It Works

by Petra CameronOctober 13, 2022,
Emission Control System- How It Works

Do you recall the three-month period when the nation was under lockdown? The roads were blocked, automobiles were parked in garages, and businesses were closed. Within one month of the lockdown, the AQI fell significantly, the trees turned greener, and the rivers became cleaner; it was a unique experience. We might live in such a pure environment if we reduce emissions and polluting sources. Our automobiles are one source of hazardous pollutants, and emission control technologies are designed to reduce their impact. Today, we will discuss what an emission control system is, how it operates, and the many types available.

What is an Emission Control System?

The vehicle's emission control system consists of a variety of functions that maintain emissions as low as feasible. Carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxide (NOx) emissions are reduced with the use of an emission control system. We may commonly divide emission control methods into two categories: active prevention and passive destruction. New technologies have lowered the pollution output of automobile engines, which have gotten significantly more sophisticated in recent years. Among the innovations include the use of the right air-to-fuel ratio, better combustion processes, and variable air-to-fuel ratio. However, we describe more effective and essential emission control strategies that are required to meet increasingly rigorous emission standards.

Catalytic Converters

The catalytic converter is a common piece of equipment utilized by all automobiles to reduce exhaust emissions. Even though catalytic converters have been in use since 1970, there have been several improvements to their operation. The two-way catalytic converter could only regulate CO and HC. However, the three-way system can additionally control oxides of Nitrogen (NOx) and is thus utilized in all current vehicles. Modern catalytic converters transform hazardous gases and toxins into carbon dioxide (CO2) and water (H2o). A cylindrical canister is attached to the exhaust pipe to house the catalytic converter. It contains precious metals such as platinum (Pt), palladium (Pd), and rhodium (Rh), which perform oxidation and transform hazardous gases into carbon dioxide (CO2) and water.

The catalytic converter operates under the influence of heat, and a deficiency of heat might reduce its overall effectiveness. As a result, when the engine is cold, the catalytic converter cannot operate at peak efficiency, and to reduce emissions, many automakers use a secondary battery to pre-heat the catalytic converter as soon as the vehicle is started. The catalytic converter is the most crucial emission control equipment for eliminating hazardous pollutants.

Evaporative Emission Control

In addition to reducing pollutants, evaporative emission control saves fuel and improves the overall economy of cars. In technical terms, an evaporative emission control system prevents hydrocarbons from evaporating from the fuel tank and recirculates them into the combustion chamber. The carbon canister that stores hydrocarbons are the primary mechanical component of this emission control device. The carbon canister captures gasoline vapors through weak chemical interactions and releases them through a purge solenoid operated by an onboard computer module.

The flammable fuel vapors are sent into the combustion chamber for burning. When refueling, the evaporation of gasoline vapors via the fuel tank lid conserves fuel and regulates pollutants. The PCV valve injects the vapors into the intake manifold of the engine.

Exhaust Gas Recirculation (EGR)

Exhaust Gas Recirculation is particularly effective for reducing emissions and maintaining the lowest feasible engine temperatures. EGR is typically available in turbocharged gasoline and diesel engines, with gasoline engines adopting the technology far earlier than diesel engines. Construction-wise, the exhaust manifold directs part of the exhaust gases into the intake manifold, which helps to reduce engine temperature and emissions overall. EGR is utilized in diesel engines to minimize NOx emissions, whilst it is utilized in petrol engines to boost efficiency.

Exhaust gases are already very hot, so you must be wondering how anything much hotter might lower the temperature. The exhaust gases are inert, which means they have already been burned. Consequently, they reduce the combustion capacity of each cylinder, which reduces the amount of heat generated; fewer heat results in fewer emissions. Notably, EGR decreases power to some degree. Thus, this approach is ineffective when absolute power is required. If the engine is not functioning at its optimal operating temperature, EGR will not operate until the engine reaches that temperature.

Diesel Particulate Filter (DPF)

The Diesel Particulate Filter (DPF) is a honeycomb filter that captures soot from the exhaust manifold after combustion. It captures all solid particles and accumulates them at a particular capacity, after which they are burned. Regeneration is the burning of soot that occurs while a car is driving in a controlled environment at specific engine RPMs.

Car manufacturers propose a regeneration cycle that should be adhered to in order to maximize the health of the engine, as driving at low speeds might hinder the regeneration process. The regeneration process requires a specific exhaust temperature and a high oxygen concentration. Modern automobiles advise the driver of the amount of DPF clogging activity, and the regeneration procedure is flawless.

Selective Catalyst Reduction (SCR)

Selective Catalyst Reduction (SCR) is another sophisticated pollution control approach that is typically employed in diesel engines with greater displacement. SCR technology, often known as Adblue, is essential for large diesel engines to meet severe BS6 standards. Adblue is a liquid form of urea that is also known as Diesel Exhaust Fluid (DEF). SCR functions in tandem with the DPF, and Adblue fluid is injected into the exhaust. The fluid interacts with NOx to produce nitrogen, water, and carbon dioxide. The transformed gases are far less hazardous than NOx and are expelled through the exhaust pipe. The SCR system may lower NOx emissions by up to 90 percent and contributes to BS6 compliance.

Frequently Asked Question

The emission control system is a broad topic; here are some of the most often-asked questions about the system.

Q1: Does catalytic converter affect emissions?

The catalytic converter is the primary pollution control equipment of a vehicle, converting the most dangerous gases into nitrogen, water, and carbon dioxide. Without a catalytic converter, a vehicle would produce significantly more hazardous pollutants and harm the environment.

Q2: How does the emission control system work?

Ans. The emission control system operates in concert with a number of other systems. The system can be broadly classified as preventative or destructive. The primary objective of the emission control system is to minimize emissions without sacrificing the vehicle's economy and performance.

Q3: Fault with emission control system

Ans. The emission control system is quite sophisticated, and current vehicles are fitted with computers that alert the driver to any malfunction. DPF blockage is the most frequent issue with the emission control system of a new automobile, as shown by the instrument cluster. If this message appears, you may either perform the regeneration procedure or take your vehicle to repair.

Q4: How to fix the emission control system?

Ans. The emission control system is quite sophisticated, and its components are concealed within the engine compartment or beneath the vehicle. Therefore, if you encounter any troubles, you should always get your vehicle inspected by a professional technician.

Q5: When the emission control system is not ready?

Ans. Most emission control systems require optimal temperature and a high oxygen concentration to function. When the engine's temperature is low, components like the catalytic converter and EGR do not function. Consequently, automakers also deal with the aftermath and modify these systems to function in all environments.

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