An experimental and numerical study on effects of exhaust gas temperature and flow rate on deposit formation in Urea-Selective Catalytic Reduction (SCR) system of modern automobiles

2017 ◽  
Vol 111 ◽  
pp. 1211-1231 ◽  
Author(s):  
S Sadashiva Prabhu ◽  
Nagaraj S Nayak ◽  
N Kapilan ◽  
Vijaykumar Hindasageri
Keyword(s):  
Selective Catalytic Reduction ◽  
Flow Rate ◽  
Catalytic Reduction ◽  
Numerical Study ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Deposit Formation ◽  
Exhaust Gas Temperature ◽  
Scr System

scholarly journals The Experimental and Simulation Study of Selective Catalytic Reduction System in a Single Cylinder Diesel Engine Using NH3as a Reducing Agent

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Manoj Kumar Athrashalil Phaily ◽  
Sreekumar Jayachandra Sreekala ◽  
Padmanabha Mohanan
Keyword(s):  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Mass Flow ◽  
Catalytic Reduction ◽  
Pt Catalyst ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Single Cylinder ◽  
Induction Rate ◽  
Exhaust Gas Temperature

Selective catalytic reduction (SCR) technology has been widely used in automotive applications in order to meet the stringent limits on emission standards. The maximum NOxconversion efficiency of an SCR depends on temperature and mass flow rate of an exhaust gas. In order to assess the suitability of Cordierite/Pt catalyst for low temperature application, an experimental work is carried out using single cylinder diesel engine for different load conditions by varying ammonia induction rate from 0.2 kg/hr to 0.8 kg/hr. The simulation is carried out using AVL FIRE for the validation of experimental results. From the study, it has been found that for 0.6 kg/hr ammonia induction rate the maximum conversion is achieved, whereas, for 0.8 kg/hr, conversion is reduced due to desorption of ammonia. Also it has been found that, at 75% of load, for all mass flow rates of ammonia the conversion was drastically reduced due to higher exhaust gas temperature and higher emission of unburnt hydrocarbons. More than 55% of NOxconversion was achieved using Cordierite/Pt catalyst at a temperature of 320°C.

Modeling and simulation of marine SCR system based on Modelica

2022 ◽  
pp. 146808742110722
Author(s):  
Jie Shi ◽  
Yuanqing Zhu ◽  
Hui Peng ◽  
Haoyu Yan ◽  
Tinghui Li ◽  
...  
Keyword(s):  
Flow Rate ◽  
Great Influence ◽  
Slip Rate ◽  
Urea Solution ◽  
Bench Test ◽  
Stoichiometric Ratio ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Exhaust Gas Temperature ◽  
Scr System

With the increasing awareness of global marine environmental protection, the emission of ship exhaust pollutants is strictly restricted. Selective catalytic reduction (SCR) technology is the mainstream technology to reduce ship NOx emission and make it meet IMO tier III regulations. A SCR reaction kinetic model based on Modelica language was established by Dymola software to predict the denitration efficiency, ammonia slip rate, and other parameters of SCR system. According to the functional structure of marine SCR system, the SCR system model is divided into urea injection module, mixer module, and SCR reactor module. The model was verified by SCR system bench test of WD10 diesel engine, which proved that the model can preferably reflect the actual situation. Using the established model, the effects of temperature, flow rate, NH3/NOx Stoichiometric Ratio (NSR), and cell density on the denitration performance of SCR system were analyzed. The results showed that the exhaust gas temperature and NSR have a great influence on the denitration efficiency. The injection amount of urea solution in marine SCR system should be based on the exhaust gas temperature and exhaust flow rate.

Compound Control Strategy Based on Active Disturbance Rejection for Selected Catalytic Reduction systems

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Jinbiao Ning ◽  
Fengjun Yan
Keyword(s):  
Control Strategy ◽  
Disturbance Rejection ◽  
Catalytic Reduction ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Model Uncertainties ◽  
Compound Control ◽  
Active Disturbance Rejection ◽  
Exhaust Gas Temperature ◽  
Scr System

Urea-based selected catalytic reduction (SCR) systems are effective ways in diesel engine after-treatment systems to meet increasingly stringent emission regulations. To achieve high NOx reduction efficiency and low NH3 slip, the control of the SCR system becomes more challenging, especially in transient operating conditions with model uncertainties. To effectively address this issue, this paper proposed a compound control strategy with a switching mechanism between an active disturbance rejection (ADR) controller and a zero-input controller. The ADR controller estimates and rejects the total (internal and external) disturbances from the SCR system when the exhaust gas temperature is high and its variation is small. The zero-input controller is used to lower ammonia surface coverage ratio to avoid high ammonia slip when exhaust gas temperature suddenly rises. The proposed control strategy is validated through a high-fidelity GT-Power simulation for a light-duty diesel engine over steady states and federal test procedure (FTP-75) test cycle. Its effectiveness is demonstrated especially in rapidly transient conditions with model uncertainties.

Modelling and parametric investigation of NOx reduction by oxidation precatalyst-assisted ammonia-selective catalytic reduction

2009 ◽  
Vol 223 (9) ◽  
pp. 1193-1206 ◽  
Author(s):  
S-C Jung ◽  
W-S Yoon
Keyword(s):  
Selective Catalytic Reduction ◽  
Low Temperatures ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Volume Ratio ◽  
Kinetic Scheme ◽  
Space Velocity ◽  
Gas Temperature ◽  
Scr System ◽  
Very High

Nitrogen oxide (NO x) reduction by the selective catalytic reduction (SCR) system assisted by an oxidation precatalyst is modelled and analytically investigated. The Langmuir—Hinshelwood SCR kinetic scheme with vanadium-based catalyst and ammonia (NH3) reductant in conjunction with the NO—NO2 conversion reaction over a platinum-based catalyst is used. The effects of the ratio of the oxidation precatalyst to the SCR monolith volume, the gas temperature, the space velocity, and the NH3-to-NO x concentration ratio on the de-NO x performance are parametrically examined. The oxidation precatalyst promotes NO x conversion at low temperatures. At intermediate temperatures, the NO x reduction is either activated or deactivated with increase in the space velocity. A higher oxidation precatalyst-to-SCR monolith volume ratio tends to promote the NO x reduction of higher space velocities. At high temperatures, the de-NO x efficiency is very high and insensitive to the space velocity. The NO x conversion efficiency depends on the NH3-to-NO x ratio at low temperatures.

Large Two-Stroke Marine Diesel Engine Operation with a High-Pressure SCR System in Heavy Weather Conditions

2020 ◽  
pp. 1-15 ◽  
Author(s):  
Michael I. Foteinos ◽  
George I. Christofilis ◽  
Nikolaos P. Kyrtatos
Keyword(s):  
High Pressure ◽  
Weather Conditions ◽  
Irregular Waves ◽  
Ship Motions ◽  
Exhaust Gas ◽  
Time Varying ◽  
Gas Temperature ◽  
Marine Diesel ◽  
Exhaust Gas Temperature ◽  
Scr System

The transient performance of a direct-drive large two-stroke marine diesel engine, installed in a vessel operating in a seaway with heavy weather, is investigated via simulation. The main engine of the ship is equipped with a selective catalytic reduction (SCR) after treatment system for compliance with the latest International Maritime Organization (IMO) rules for NOx reduction, IMO Tier III. Because of limitations of exhaust gas temperature at the inlet of SCR systems and the low temperature exhaust gases produced by marine diesel engines, in marine applications, the SCR system is installed on the high-pressure side of the turbine. When a ship sails in heavy weather, it experiences a resistance increase, wave-induced motions, and a time-varying flow field in the propeller, induced by ship motions. This results in a fluctuation of the propeller torque demand and, thus, a fluctuation in engine power and exhaust gas temperature, which can affect engine and SCR performance. To investigate this phenomenon and take into account the engine–propeller interaction, the entire propulsion plant was modeled, namely, the slow-speed diesel propulsion engine, the high-pressure SCR system, the directly driven propeller, and the ship's hull. To simulate the transient propeller torque demand, a propeller model was used, and torque variations due to ship motions were taken into account. Ship motions in waves and wave-added resistance were calculated for regular and irregular waves using a 3D panel code. The coupled model was validated against available measured data from a shipboard propulsion system in good weather conditions. The model was then used to simulate the behavior of a Tier III marine propulsion plant during acceleration from low to medium load, in the presence of regular and irregular waves. The effect of the time-varying propeller demand on the engine and the SCR system was investigated. 1. Introduction The effect of waves on a marine propulsion system is a complex phenomenon involving interactions between different subsystems of the propulsion plant, i.e., the prime mover, the propeller, and the ship's hull. Ships sailing in heavy weather conditions experience a resistance increase, wave-induced motions, and a time-varying flow field in the propeller. This leads to a fluctuation of the propeller torque demand which results in a fluctuation in engine-produced power and exhaust gas temperature.

Evaluating the Influence of Biogas Flow Rate and Addition of Cerium Oxide Nanoparticles on the Performance of a Dual Fuel Engine Using Taguchi Method

2017 ◽  
Vol 17 ◽  
pp. 179-193
Author(s):  
M. Feroskhan ◽  
Ismail Saleel
Keyword(s):  
Cerium Oxide ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Equivalence Ratio ◽  
Volumetric Efficiency ◽  
Dual Fuel ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Brake Thermal Efficiency ◽  
Exhaust Gas Temperature

Biogas is a promising alternative fuel for compression ignition (CI) engines owing to its renewability and carbon neutrality. In this study, biogas was used along with diesel in a CI engine in dual fuel mode, i.e. biogas is inducted along with air and this mixture is ignited by the in-cylinder injection of diesel. The viability of using cerium oxide (CeO2) nanoparticles as an additive to diesel was also explored. The effects of three parameters, viz. biogas flow rate and concentration of CeO2 nanoparticles and applied load on engine performance were investigated under constant speed operation. These parameters were varied in the ranges of 0 - 12 litre/min, 0 - 35 mg/litre and 5 - 22 N.m respectively. The experimental test matrix was reduced to 16 trials using Taguchi’s approach. Performance was quantified in terms of brake thermal efficiency, volumetric efficiency, diesel consumption, exhaust gas temperature and overall equivalence ratio. The criteria for optimum performance were defined as maximum brake thermal and volumetric efficiencies and minimum diesel consumption, exhaust gas temperature and overall equivalence ratio. Optimum operating conditions were identified by evaluating the signal to noise ratio (SNR) for each performance parameter and using the higher-the-better (HTB) or lower-the-better (LTB) condition as applicable. Contributions of individual parameters towards the performance indices were found using ANOVA. Load was found to be the main contributing factor for brake thermal efficiency, exhaust gas temperature and overall equivalence ratio. Biogas flow rate showed significant contribution towards volumetric efficiency. Biogas flow rate and load had comparable influences on diesel consumption. Addition of nanoparticles showed minor contribution towards all the performance parameters.

Model Predictive Control of Integrated Hybrid Electric Powertrains Coupled With Aftertreatment Systems

2014 ◽  
Author(s):  
Junfeng Zhao ◽  
Junmin Wang
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Fuel Economy ◽  
Catalytic Reduction ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
System Temperature ◽  
Hybrid Electric ◽  
Exhaust Gas Temperature ◽  
Aftertreatment Systems

For hybrid electric vehicles (HEVs), especially for diesel-electric hybrid vehicles, the low exhaust gas temperature induced by the hybridization and fuel economy optimization will bring significant impact on the performance of the exhaust gas aftertreatment systems, and may consequently lead to violation of the tailpipe emission constraints. To investigate the influence of diesel powertrain hybridization on the aftertreatment system and tailpipe emissions, an integrated HEV model is established by incorporating the thermodynamics models of the aftertreatment systems. This comprehensive model is able to predict engine-out nitrogen oxides (NOx) concentration, exhaust gas temperature, and to describe the temperature dynamics in the aftertreatment systems. A static map of selective catalytic reduction (SCR) system temperature-dependent de-NOx efficiency is utilized, so that the tailpipe NOx can be predicted. To investigate the tradeoff between fuel consumption and emissions for diesel HEV with aftertreatment systems, a preliminary study is carried out on optimally balancing both aspects via a model predictive control scheme. This controller is designed with an explicit consideration of HEV tailpipe NOx emission constraint. The simulation results show that the HEV tailpipe NOx emissions can be regulated by slightly sacrificing the fuel economy.

scholarly journals A CFD Study on Flow Control of Ammonia Injection for Denitrification Processes of SCR Systems in Coal-Fired Power Plants

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1352
Author(s):  
Min-Gyu Kim ◽  
Deok-Cheol Seo ◽  
Hee-Taeg Chung
Keyword(s):  
Selective Catalytic Reduction ◽  
Flow Rate ◽  
Power Plants ◽  
Catalytic Reduction ◽  
Molar Ratio ◽  
Exhaust Gas ◽  
Two Dimensional ◽  
Inlet Conditions ◽  
Denitrification Process ◽  
Ammonia Injection

The selective catalytic reduction method is a useful method for the denitrification process of exhaust gas emitted from industrial facilities. The distribution of the ammonia–nitrogen oxide mixing ratio at the inlet of the catalyst layers is important in the denitrification process. In this study, a computational analysis technique was used to improve the uniformity of the NH3/NO molar ratio by controlling the flow rate of the ammonia injection nozzle according to the flow distribution of nitrogen oxides in the inlet exhaust gas of the denitrification facility. The application model was simplified to the two-dimensional array adopted from the existing selective catalytic reduction (SCR) process in the large-scaled coal-fired power plant. As the inlet conditions, four (4) types of flow pattern were simulated, i.e., parabolic, upper-skewed, lower-skewed, and random. The flow rate of the eight (8) nozzles installed in the ammonia injection grid was controlled by Design Xplorer as the optimization tool. In order to solve the two-dimensional steady, incompressible, and viscous flow fields, the commercial software named ANSYS Fluent was used with the κ-ε turbulence model. The root mean square of NH3/NO molar ratio at the inlet of the catalyst layer has been improved from 84.6% to 90.1% by controlling the flow rate of the ammonia injection nozzles. From the present numerical simulation, the operation guide could be drawn for the ammonia injection nozzles in SCR DeNOx facilities.

scholarly journals Experimental Study of Direct Water Injection Effect on NOx Reduction from The Gas Fuel

2020 ◽  
Vol 76 (3) ◽  
pp. 92-108
Author(s):  
Mostafa Raafat Kotob ◽  
Tianfeng Lu ◽  
Seddik S. Wahid
Keyword(s):  
Chemical Reaction ◽  
Flow Rate ◽  
Nox Reduction ◽  
Water Injection ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Direct Water Injection ◽  
Gas Fuel ◽  
Injection Effect ◽  
Exhaust Gas Temperature

Direct Water Injection (DWI) is commonly used in many nitrogen oxides (NOx) emissions control applications due to its effect to reduce the adiabatic flame temperature. In this paper an experimental test rig is designed to study the effect of water injection spray inside a simulated gas turbine combustor from the gas fuel. The practical work introduced by the chemical reaction methodology followed by the experiment which was presented and discussed carefully. Results are obtained in term of the exhaust gas temperature and different injection parameters including position, direction and fuel mass flow rate on the nitrogen oxide emission value in PPM (Parts per Million) at different conditions. The results showed that the best water injection effect was obtained at 45° degree inside the primary air zone. Injection location has a major effect on the NOx reduction as the best injected location is the Primary air zone compared with the direct fuel nozzle tip due to the increase of the water droplets residence time inside the combustor and perform a vortex that will affect the reduction of exhaust gas temperature and NOx emission respectively. The huge impact was observed at LPG (Liquefied Petroleum gas) flowrate 2.7L/min and water to fuel ratio about 0.4 as the NOx value was decreased about 73% from almost 381 PPM to 73 PPM. The chemical reaction arrangement order methodology presented good agreement with the experimental results at different fuel flow rate and equivalence ratio. The chemical Reaction equations were implemented to calculate the different adiabatic flame temperatures which is experimentally known as the exhaust gas temperature and impacted directly the NOx emission results.

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