Effect of Engine Operating Conditions and Coolant Temperature on the Physical and Chemical Properties of Deposits From an Automotive Exhaust Gas Recirculation Cooler

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Bhaskar Prabhakar ◽  
André L. Boehman
Keyword(s):  
Heat Exchanger ◽  
Load Condition ◽  
Exhaust Gas Recirculation ◽  
Control Flow ◽  
Operating Conditions ◽  
Coolant Temperature ◽  
Exhaust Gas ◽  
Low Load ◽  
Egr Cooler ◽  
Gas Recirculation

The effect of engine operating conditions on exhaust gas recirculation (EGR) cooler fouling was studied using a 6.4 L V-8 common rail turbodiesel engine. An experimental setup, which included a custom-made shell and tube heat exchanger (EGR cooler) with six surrogate tubes, was designed to control flow variables independently. The engine was operated at 2150 rpm, 203 Nm and 1400 rpm, 81 Nm, representing medium and low load conditions, respectively, and the coolant to the heat exchanger was circulated at 85 °C and 40 °C. Heat exchanger effectiveness and pressure drop was monitored throughout the tests. Deposits from the EGR cooler were collected every 1.5 h for a total of 9 h, and their microstructure was analyzed using a scanning electron microscope while their chemical composition was analyzed using a pyrolysis GC-MS apparatus, and the elemental weight percentages were obtained using a CHN analyzer. The results of these analyses showed that the effectiveness of the EGR cooler drops rapidly initially and asymptotes in a few hours. The medium load condition had a higher effectiveness loss due to a greater accumulation of deposits inside the EGR cooler, mostly due to increased thermophoresis, and produced smaller and coarse particles. The low load condition had lower effectiveness loss but produced bigger particles mostly due to excess hydrocarbons. Coolant temperature played a significant role in altering the deposit microstructure and in increasing the amount of condensed hydrocarbons. More deposits were produced for the cold coolant condition, indicating that lower coolant temperature promotes greater hydrocarbon condensation and thermophoresis. These results indicate the complex nature of fouling in automotive heat exchangers.

Development and performance estimation of an exhaust gas recirculation cooler with dimpled rectangular tubes

2011 ◽  
Vol 225 (3) ◽  
pp. 384-397
Author(s):  
Y-H Seo ◽  
S-C Heo ◽  
T-W Ku ◽  
J Kim ◽  
B-S Kang
Keyword(s):  
Heat Exchange ◽  
Structural Integrity ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Performance Estimation ◽  
Exhaust Gas ◽  
Core Tube ◽  
Egr Cooler ◽  
Gas Recirculation ◽  
Rectangular Tubes

In this study, an exhaust gas recirculation (EGR) cooler with dimpled rectangular tubes, whose heat exchange effectiveness is higher than that of a conventional cooler, is developed. To maximize the heat transfer between the exhaust gas and coolant, the dimples are formed on the surface of the heat exchange tubes. A dimpled-tube manufacturing process is established that comprises: dimple shape forming, edge bending, centre v-notch bending, compression, and plasma welding. The high effectiveness of the dimple-type EGR cooler is confirmed by the effectiveness-NTU method and experimental approaches under normal operating conditions. It is also important to verify the structural integrity, in view of the practical uses of the dimple-type EGR cooler. In order to confirm the safety of the EGR cooler, finite element analyses are carried out for each component, such as the oval core tube with a dimpled shape. The structural integrity under thermal stress and pressure, which are caused by gas and coolant flows in the shell and tubes, is evaluated through thermal and structural analyses.

Condensation Analysis of Exhaust Gas Recirculation System for Heavy-Duty Trucks

2011 ◽  
Vol 3 (4) ◽  
Author(s):  
Bing-Jian Yang ◽  
Shaolin Mao ◽  
Orhan Altin ◽  
Zhi-Gang Feng ◽  
Efstathios E. Michaelides
Keyword(s):  
Heat Exchanger ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Condensation Process ◽  
Transfer Model ◽  
Exhaust Gas ◽  
Heavy Duty ◽  
Gas Recirculation

The exhaust gas recirculation (EGR) system has been widely used in the automotive and heavy-duty trucks to reduce NOx, SOx, and other controlled emissions. A liquid-cooled or air-cooled heat exchanger is the main constituent of the EGR system. The heat exchanger decreases the temperature of the exhaust gases mixture that flows through the EGR channels and the lower temperatures reduce the content of the controlled gas emissions. Condensation of water vapor is an undesirable by-product of the EGR systems because, in combination with the emission gases, it forms the corrosive sulfuric and nitric acids. The U.S. EPA has suggested that engine makers should turn off their EGR systems periodically to avoid the formation of the corrosive sulfuric and nitric acids. In order to accurately predict the corrosion process, a condensation model has been developed to investigate the rates of formation and diffusion of nitric acid and sulfuric acid to the cold tube surface. A three-dimensional computational fluid dynamics (CFD) simulation has been conducted for a typical EGR cooler during normal operating conditions of Tier 4 heavy-duty trucks. A lumped, 1D heat and mass transfer model has also been developed to study the most important physical aspects of the condensation process. The CFD and the analytical results of the rate of condensation and local fluid properties are an important and inexpensive complement to more expensive experimental measurements and testing. Such models may be used to improve the design and to optimize the operating conditions of the EGR systems and may become valuable tools in the design and manufacturing of the next generation of EGR systems for diesel engines. The model developed is general and the techniques and numerical results of this study may be extended to engine reliability, corrosion reduction, and damage prevention of other industrial engines.

Propensity of Soot Deposition in a Rectangular Exhaust Gas Recirculation Cooler Using Kalman Filter

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Alireza Mirsadraee ◽  
M. Reza Malayeri
Keyword(s):  
Kalman Filter ◽  
Diesel Engines ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Process Noise ◽  
Soot Deposition ◽  
Noise Covariance ◽  
Egr Cooler ◽  
Gas Recirculation

The detection of fouling in exhaust gas recirculation (EGR) coolers of diesel engines should be fast and accurate. This would facilitate deciding an effective strategy to combat fouling and to prolong the lifetime of EGR coolers. In the present study, the propensity of soot deposition in a rectangular EGR cooler is modeled using Kalman filters. Noises, coherent feature of many deposition processes which can be resulted from measurement sensors such as thermocouples or incidental deposit flake-off, are also considered in the model. The Kalman filter minimizes the estimation error covariance by considering the measurement and process noise covariance matrices while it can simultaneously handle the noisy data. The results are characterized with measurement process noise covariance. The relation between these two defines the smoothness and shape of the estimated trend of fouling resistance. Comparisons of the experimental data and the resultant model confirmed the usefulness of the applied method for various operating conditions of an EGR cooler prone to particulate deposition of soot particles. The paper proceeds with the impact of such models in monitoring fouling and taking an appropriate mitigation approach in diesel engines.

scholarly journals Learning reference governor for cycle-to-cycle combustion control with misfire avoidance in spark-ignition engines at high exhaust gas recirculation–diluted conditions

2020 ◽  
Vol 21 (10) ◽  
pp. 1819-1834
Author(s):  
Bryan P Maldonado ◽  
Nan Li ◽  
Ilya Kolmanovsky ◽  
Anna G Stefanopoulou
Keyword(s):  
Combustion Process ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Intake Manifold ◽  
Exhaust Gas ◽  
Model Free ◽  
Recirculation Rate ◽  
Valve Position ◽  
Gas Recirculation ◽  
Reference Governor

Cycle-to-cycle feedback control is employed to achieve optimal combustion phasing while maintaining high levels of exhaust gas recirculation by adjusting the spark advance and the exhaust gas recirculation valve position. The control development is based on a control-oriented model that captures the effects of throttle position, exhaust gas recirculation valve position, and spark timing on the combustion phasing. Under the assumption that in-cylinder pressure information is available, an adaptive extended Kalman filter approach is used to estimate the exhaust gas recirculation rate into the intake manifold based on combustion phasing measurements. The estimation algorithm is adaptive since the cycle-to-cycle combustion variability (output covariance) is not known a priori and changes with operating conditions. A linear quadratic regulator controller is designed to maintain optimal combustion phasing while maximizing exhaust gas recirculation levels during load transients coming from throttle tip-in and tip-out commands from the driver. During throttle tip-outs, however, a combination of a high exhaust gas recirculation rate and an overly advanced spark, product of the dynamic response of the system, generates a sequence of misfire events. In this work, an explicit reference governor is used as an add-on scheme to the closed-loop system in order to avoid the violation of the misfire limit. The reference governor is enhanced with model-free learning which enables it to avoid misfires after a learning phase. Experimental results are reported which illustrate the potential of the proposed control strategy for achieving an optimal combustion process during highly diluted conditions for improving fuel efficiency.

A comparative study into the effects of pre and post catalyst exhaust gas recirculation on the onset of knock

2020 ◽  
pp. 146808742096229
Author(s):  
Dominic Parsons ◽  
Simon Orchard ◽  
Nick Evans ◽  
Umud Ozturk ◽  
Richard Burke ◽  
...  
Keyword(s):  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Engine Combustion ◽  
Low Load ◽  
Fine Control ◽  
Novel Method ◽  
Gdi Engine ◽  
Stochastic Phenomena ◽  
Gas Recirculation ◽  
Onset Angle

Exhaust gas recirculation (EGR) is proven as a valuable technology for controlling knock whilst maintaining lambda one operation, and is also capable of providing efficiency gains at low load. Despite this few studies in the literature address the question of EGR composition effects, namely whether the EGR gas is sourced from before or after the catalyst, and this remains an area which is often overlooked whilst investigating EGR performance. This paper demonstrates a novel method combining experiment air-path emulation and in-depth data processes to compare the effect of EGR catalysis on the angle of knock onset in a 1L GDI engine. Since initial temperature and pressure have a significant impact on knocking behaviour, an artificial boosting rig replaced the turbomachinery. This enabled fine control over the engine boundary conditions to ensure parity between the catalysed and un-catalysed cases. To overcome the difficulty of comparing stochastic phenomena in an inherently variable dataset, a pairing method was combined with Shahlari and Ghandhi’s angle of knock onset determination method to assess the effects of EGR composition on knock onset for EGR rates ranging from 9% to 18%. The air path emulation system stabilised the engine combustion to provide a suitably rich dataset for analysing knock using the pairing method. Catalysed EGR improved the mean knock onset angle by 0.55 CAD, but due to the inherent variability in cylinder pressure data this only equated to a 58.3% chance of a later knock onset angle for catalysed EGR in any given pair of comparative cycles.

Analysis of the Exhaust Gas Recirculation System Performance in Modern Diesel Engines

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Stefano d'Ambrosio ◽  
Alessandro Ferrari ◽  
Ezio Spessa
Keyword(s):  
Control Valve ◽  
Experimental Tests ◽  
Detailed Comparison ◽  
Exhaust Gas Recirculation ◽  
Valve Lift ◽  
Exhaust Gas ◽  
Flow Area ◽  
Tube Type ◽  
Egr Cooler ◽  
Gas Recirculation

Exhaust gas recirculation (EGR) is extensively employed in diesel combustion engines to achieve nitrogen oxides emission targets. The EGR is often cooled in order to increase the effectiveness of the strategy, even though this leads to a further undesired impact on particulate matter and hydrocarbons. Experimental tests were carried out on a diesel engine at a dynamometer rig under steady-state speed and load working conditions that were considered relevant for the New European Driving Cycle. Two different shell and tube-type EGR coolers were compared, in terms of the pressure and temperature of the exhaust and intake lines, to evaluate thermal effectiveness and induced pumping losses. All the relevant engine parameters were acquired along EGR trade-off curves, in order to perform a detailed comparison of the two coolers. The effect of intake throttling operation on increasing the EGR ratio was also investigated. A purposely designed aging procedure was run in order to characterize the deterioration of the thermal effectiveness and verify whether clogging of the EGR cooler occurred. The EGR mass flow-rate dependence on the pressure and temperature upstream of the turbine as well as the pressure downstream of the EGR control valve was modeled by means of the expression for convergent nozzles. The restricted flow-area at the valve-seat passage and the discharge coefficient were accurately determined as functions of the valve lift.

scholarly journals Cyclic NO2:NOx ratio from a diesel engine undergoing transient load steps

2019 ◽  
Vol 22 (1) ◽  
pp. 284-294 ◽  
Author(s):  
FCP Leach ◽  
MH Davy ◽  
MS Peckham
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Formation Mechanisms ◽  
Exhaust Gas ◽  
Work Cycle ◽  
Wide Range ◽  
Gas Recirculation ◽  
Aftertreatment Systems

As the control of real driving emissions continues to increase in importance, the importance of understanding emission formation mechanisms during engine transients similarly increases. Knowledge of the NO2/NOx ratio emitted from a diesel engine is necessary, particularly for ensuring optimum performance of NOx aftertreatment systems. In this work, cycle-to-cycle NO and NOx emissions have been measured using a Cambustion CLD500, and the cyclic NO2/NOx ratio calculated as a high-speed light-duty diesel engine undergoes transient steps in load, while all other engine parameters are held constant across a wide range of operating conditions with and without exhaust gas recirculation. The results show that changes in NO and NOx, and hence NO2/NOx ratio, are instantaneous upon a step change in engine load. NO2/NOx ratios have been observed in line with previously reported results, although at the lightest engine loads and at high levels of exhaust gas recirculation, higher levels of NO2 than have been previously reported in the literature are observed.

Optimization of a diesel engine calibration for operating with a residual glycerol-derived biofuel

2019 ◽  
pp. 146808741989153 ◽  
Author(s):  
Magín Lapuerta ◽  
Ángel Ramos ◽  
Sara Rubio ◽  
Carles Estévez
Keyword(s):  
Particulate Matter ◽  
Fatty Acid ◽  
Diesel Fuel ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Transport Sector ◽  
Exhaust Gas ◽  
Engine Calibration ◽  
Particulate Matter Emissions ◽  
Gas Recirculation

The new European directive for the promotion of renewable energy mandates an increase in the share of advanced and waste-based biofuels in the transport sector. In this study, an advanced glycerol-derived biofuel was used as a component of a ternary blend, denoted as o·bio®. This blend included 27.4 %v/v of fatty acid glycerol formal ester, 69.6 %v/v of fatty acid methyl ester and 3 %v/v of acetals obtained as a by-product of the fatty acid glycerol formal ester production process (which were proved to improve cold-flow properties). Finally, o·bio® was blended with diesel fuel at a content of 20 %v/v. Two operating conditions based on usual driving modes were selected, where the engine calibration could be re-optimized after the change of fuel, corresponding to vehicle velocities of 50 and 70 km/h. Since the main effect of the blend used is to reduce particulate matter emissions, exhaust gas recirculation was increased and injection was delayed, so that the initial benefits in particulate matter emissions could be re-distributed into benefits in both particulate matter and nitrogen oxides (NOx) emissions. From a combined analysis of the particulate matter–NOx trade-off and trying to limit the negative effect of delaying injection on fuel consumption, the final proposal was to set an additional 6% exhaust gas recirculation at 50 km/h and an additional 3% exhaust gas recirculation at 70 km/h, while delaying injection 2 °CA after top dead center at both vehicle operating conditions with respect to the original calibration. The use of the blend along with the optimization of the engine calibration is expected to reduce particulate matter and NOx emissions by around 50% with a vehicle speed condition of 50 km/h and to reduce particulate matter and NOx emissions by around 30% and 40% at 70 km/h with respect to diesel fuel emissions.

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