HEAT RECOVERY TECHNOLOGIES FROM INTERNAL COMBUSTION ENGINES

EXHAUST EMISSION REDUCTION TECHNOLOGIES FOR DIESEL ENGINESPankaj gupta142116517Stress and vibration

1Diesel engines have high thermal efficiency, lower fuel consumption, lower maintenance cost and lower CO2 emissions compared with equivalent gasoline engines.

Higher emissions of oxides of nitrogen (NOx) and particulate matter (PM) have been noticed as major problems.

These emissions cause environmental pollution and are potentially harmful to human health.

Undesirable emissions also include unburned hydrocarbons (HC) and carbon monoxide (CO).

INTRODUCTIONComposition of diesel engine Exhaust emissions [1]

ObjectivesTo review the major technologies being used for diesel engine emission reductions, recent developments in this area and future scope of these technologies.

To give an insight about the practical limitations and challenges in the application of emission reduction technologies.

To explore emission reduction strategies in order to comply with the stringent Euro norms.

To suggest some of the key parameters to be considered while arriving at right emission control strategy.Growing concern for human health and environment led to the formation of stringent emission standards such as Euro V and Euro VI.Engine manufacturers are forced to implement latest emission reduction technologies in order to comply with the Euro norms.There are various emission reduction technologies available for emission reduction.No common approach for emission control emerged from the literature review.It is likely that a combination of the emission reduction technologies would be able to comply with the Euro V and Euro VI norms.

Conclusions Drawn from literature reviewEmission standards for diesel engine passenger cars[2]

Major emission reduction technologiesEmission Reduction SystemEmissions ReducedExhaust Gas Recirculation(EGR)NOxDiesel Oxidation Catalysts (DOC)HC, CODiesel Particulate Filters (DPF)PMSelective Catalytic Reduction (SCR)NOxLean Nox Trap(LNT)NOx

Exhaust gas recirculation[3] The dilution or oxygen displacement effect

The thermal effect

The chemical effect

EGR is an effective method for NOx control. EGR has following effects :- Most of the NOx reduction is due to the dilution effect, with a small additional contribution due to the chemical effect and thermal effect.Types of Egr[4]

Experimental study on EGR[5]

results

Thermal efficiency was found to have slightly increased with EGR at lower engine loads. At higher engine loads, the thermal efficiency remains unaffected by EGR.These graphs show that HC and CO emissions increase with increasing EGR.

The degree of reduction in NOx at higher loads is higher.

Higher smoke opacity of the exhaust is observed when the engine is operated with EGR compared to without EGR. The variation in the smoke opacity level at high loads was higher compared to that at lower loads.

As the EGR rate is increased, volumetric efficiency decreases.Carbon deposits on the various parts of the engine operated with EGR system is significantly more than that of engine operated without EGR.

The higher carbon deposits in the EGR system seem to be because of higher soot formation.Diesel particulate filters[6] DPF is employed in diesel engines to physically trap the particulate matter (PM) in exhaust gas.A wall flow DPF is most common type. It consists of large number of channels, with alternate ends of channel matrix plugged.The walls are made up of ceramic filtering material such as silicon carbide or cordierite.

Problems associated with DpfsTraps are effective in controlling the solid fraction of PMs, but may have limited effectiveness, or be totally ineffective, in controlling the non-solid fractions of PM, such as the SOF or sulphate particulates.DPFs also causes an increase in exhaust back pressure which in turn increases the BSFC.

DPFs can achieve up to 90% PM reduction in certain conditions.

Selective catalytic reduction[7] The system uses a metallic or ceramic wash-coated catalyzed substrate.Least affected by sulphur content of fuel.In addition to Nox, SCR reduce HC emissions up to 80% and PM emissions up to 30%.On board requirement of urea reduces its utilization.

V SCR - Vanadium based catalyst Catalyst A Copper zeolite catalystCatalyst B Iron zeolite catalystBoth Zeolite based catalysts show better high temperature conversion than the conventional vanadium based catalyst.Lean Nox TRAP[9]

DesulphurizationThe durability of LNTs is directly linked to sulphur removal by regeneration.Sulphur is removed from the trap by periodic high temperature excursions under reducing conditions, a procedure called DeSOx.

Diesel oxidation catalyst[10]A diesel oxidation catalyst (DOC) functions by oxidising CO and any unburnt HC into CO2 & water over a platinum group metal.

DOCs are able to remove soluble organic fraction (SOF) of PM.

A diesel oxidation catalyst consists of a stainless steel canister that contains a honeycomb structure called a substrate. Substrate may be made of ceramic material or metal foil.The interior surfaces are coated with catalytic metals such as platinum and/or palladium.conclusionsEGR is an effective method of reducing NOx emissions but it aggravates the trade-off between NOX and particulate emissions, especially at high loads.Cooled EGR gives lower thermal efficiency than hot EGR but makes possible lower NOX emissions.The advantage of using EGR and DPF is that no special fuelling infrastructure is required, however the major disadvantage is the fuel consumption penalty (approx. 3%) incurred due to the incomplete combustion from EGR and exhaust gas back pressure in from DPF.SCR is the most promising technology and could be anticipated as a future technology for emission control. references[1]. Jaffar Hussain, K. Palaniradja, N. Alagumurthi and R. Manimaran Effect of Exhaust Gas Recirculation (EGR) on Performance and Emission characteristics of a Three Cylinder Direct Injection Compression Ignition Engine Alexandria Engineering Journal (2012) 51, 241247.[2].Emission Standards: Europe: Cars and Light Trucks :- https://www.dieselnet.com/standards/eu/ld.php 2/4[3]. Federico Millo, Paolo Ferrero Giacominetto and Marco Gianoglio Bernardi Analysis of different exhaust gas recirculation architectures for passenger car Diesel engines Applied Energy 98 (2012) 7991.[4].AVINASH KUMAR AGRAWAL, SHRAWAN KUMAR SINGH, SHAILENDRA SINHA and MRITUNJAY KUMAR SHUKLA1 Effect of EGR on the exhaust gas temperature and exhaust opacity in compression ignition engines Sadhana Vol. 29, Part 3, June 2004, pp. 275284.[5]. Deepak Agarwal, Shrawan Kumar Singh and Avinash Kumar Agarwal Effect of Exhaust Gas Recirculation (EGR) on performance, emissions, deposits and durability of a constant speed compression ignition engine Applied Energy 88 (2011) 29002907[6].Diesel Particulate Filters by W. Addy Majewski www.DieselNet.com. Ecopoint Inc. Revision 2001.07b.

references[7]. Exhaust Gas Emission Control Today and Tomorrow by MAN Diesel & turbo.[8]. Diesel Engine Emissions and Their Control : AN OVERVIEW By Tim Johnson Corning Environmental Technologies, Corning Incorporated, HP-CB-2-4, Corning, NY 14831, U.S.A.[9]. Ccile Favre, John May & Dirk Bosteels EMISSIONS CONTROL TECHNOLOGIES TO MEET CURRENT AND FUTURE EUROPEAN VEHICLE EMISSIONS LEGISLATION.[10]. PALLADIUM USE IN DIESEL OXIDATION CATALYSTS : Platinum 2009Thank you