Exhaust valve profile modulation for improved diesel engine curb idle aftertreatment thermal management

2021 ◽  
pp. 146808742096910
Author(s):  
Mrunal C Joshi ◽  
Dheeraj Gosala ◽  
Gregory M Shaver ◽  
James McCarthy ◽  
Lisa Farrell
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Thermal Management ◽  
Exhaust Valve ◽  
Outlet Temperature ◽  
Exhaust Manifold ◽  
Warm Up ◽  
Valve Opening ◽  
Active Regeneration ◽  
Negative Valve Overlap

Rapid warm-up of a diesel engine aftertreatment system (ATS) is a challenge at low loads. Modulating exhaust manifold pressure (EMP) to increase engine pumping work, fuel consumption, and as a result, engine-outlet temperature, is a commonly used technique for ATS thermal management at low loads. This paper introduces exhaust valve profile modulation as a technique to increase engine-outlet temperature for ATS thermal management, without requiring modulation of exhaust manifold pressure. Experimental steady state results at 800 RPM/1.3 bar BMEP (curb idle) demonstrate that early exhaust valve opening with negative valve overlap (EEVO+NVO) can achieve engine-outlet temperature in excess of 255°C with 5.7% lower fuel consumption, 12% lower engine out NOx and 20% lower engine-out soot than the conventional thermal management strategy. Late exhaust valve opening with internal EGR via reinduction (LEVO+Reinduction) resulted in engine-outlet temperature in excess of 280°C, while meeting emission constraints at no fuel consumption penalty. This work also demonstrates that LEVO in conjunction with modulation of exhaust manifold pressure results in engine-outlet temperature in excess of 340°C while satisfying desired emission constraints. Aggressive use of LEVO can result in engine-outlet temperatures of 460°C, capable of active regeneration of DPF at curb idle, without the significant increase in engine-out soot emissions seen in previously studied strategies.

Diesel engine aftertreatment warm-up through early exhaust valve opening and internal exhaust gas recirculation during idle operation

2017 ◽  
Vol 19 (7) ◽  
pp. 758-773 ◽  
Author(s):  
Dheeraj B Gosala ◽  
Aswin K Ramesh ◽  
Cody M Allen ◽  
Mrunal C Joshi ◽  
Alexander H Taylor ◽  
...  
Keyword(s):  
Steady State ◽  
Diesel Engine ◽  
Large Fraction ◽  
Test Procedure ◽  
Exhaust Gas Recirculation ◽  
Exhaust Valve ◽  
Exhaust Gas ◽  
Warm Up ◽  
Valve Opening ◽  
Gas Recirculation

A large fraction of diesel engine tailpipe NOx emissions are emitted before the aftertreatment components reach effective operating temperatures. As a result, it is essential to develop technologies to accelerate initial aftertreatment system warm-up. This study investigates the use of early exhaust valve opening (EEVO) and its combination with negative valve overlap to achieve internal exhaust gas recirculation (iEGR), for aftertreatment thermal management, both at steady state loaded idle operation and over a heavy-duty federal test procedure (HD-FTP) drive cycle. The results demonstrate that implementing EEVO with iEGR during steady state loaded idle conditions enables engine outlet temperatures above 400 °C, and when implemented over the HD-FTP, is expected to result in a 7.9% reduction in tailpipe-out NOx.

Optimal Exhaust Valve Opening Control for Fast Aftertreatment Warm Up in Diesel Engines

2018 ◽  
Author(s):  
Rasoul Salehi ◽  
Anna G. Stefanopoulou
Keyword(s):  
Fuel Consumption ◽  
Catalytic Reduction ◽  
Test Procedure ◽  
Careful Consideration ◽  
Exhaust Valve ◽  
Power Stroke ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Warm Up ◽  
Valve Opening

This paper proposes to optimally adjust the exhaust valve opening (EVO) timing for faster selective catalytic reduction (SCR) aftertreatment system warm-up during the cold start phase of the federal test procedure (FTP). Early termination of the power stroke by EVO timing advance increases the engine exhaust gas temperature. It, on the other hand, causes exhaust flow rate reduction that decreases the coefficient of the heat transfer from the exhaust gas to the catalyst. The competing effects along with the fuel consumption increase associated with early EVO need careful consideration and the optimal EVO timing is a load-dependent balance of all these effects. This careful balance is achieved in this paper by dynamic programing (DP). Specifically, the minimum time to light-off (TTL) is formulated and applied to the cold phase of the FTP. A high fidelity detailed and verified engine and aftertreatment model is effectively simplified to enable utilizing computationally expensive DP optimization algorithm. Optimization results indicate that advancing the EVO reduces the TTL for the SCR catalyst from 659 s to 500 s, a 24% reduction. This fastest possible increase in the SCR temperature is shown to be with an expense of 4.1% increase in the fuel consumption. The results are dependent to the target light-off temperature and the load profile. Assuming a specific light-off temperature and the FTP, possible rule-based scenarios for online optimization are discussed.

Internal exhaust gas recirculation via reinduction and negative valve overlap for fuel-efficient aftertreatment thermal management at curb idle in a diesel engine

2021 ◽  
pp. 146808742098459
Author(s):  
Mrunal C Joshi ◽  
Gregory M Shaver ◽  
Kalen Vos ◽  
James McCarthy ◽  
Lisa Farrell
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Thermal Management ◽  
Lower Fuel Consumption ◽  
Low Load ◽  
Negative Valve Overlap ◽  
Valve Overlap ◽  
Gas Recirculation ◽  
Cycle Efficiency ◽  
Management Operation

Low air-flow diesel engine strategies are advantageous during low load operation to maintain temperatures of a warmed-up aftertreatment system (ATS) while reducing fuel consumption and engine-out emissions. This paper presents results at curb idle for internal EGR (iEGR) that demonstrate low airflow and reduced engine-out emissions during fuel-efficient ATS temperature maintenance operation. Internal EGR via reinduction and trapping using negative valve overlap (NVO) are compared to each other, conventional operation and to other low airflow approaches including cylinder deactivation (CDA). At 800 RPM/1.3 bar BMEP (curb idle) iEGR via reinduction enables 200°C engine-out temperature combined with 70% lower NO X, 35% lower fuel consumption, and 40% lower exhaust flow rate than conventional thermal management operation. Internal EGR via trapping using NVO resulted in an engine-out temperature of 185°C, with 56% lower NO X and 25% lower fuel consumption than conventional thermal management operation. Both iEGR strategies have lower engine-out temperatures and higher exhaust flow rates than CDA. No external EGR is required for either iEGR strategy. “iEGR via reinduction” outperforms “iEGR via NVO” as a result of higher open cycle efficiency (via less pumping work) and higher closed-cycle efficiency (via higher specific heat ratio).

scholarly journals Thermal Management Opportunity on Lubricant Oil to Reduce Fuel Consumption and Emissions of a Light-Duty Diesel Engine

2021 ◽  
Vol 312 ◽  
pp. 07023
Author(s):  
Davide Di Battista ◽  
Fabio Fatigati ◽  
Marco Di Bartolomeo ◽  
Diego Vittorini ◽  
Roberto Cipollone
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Thermal Management ◽  
Internal Combustion Engines ◽  
Thermal Stabilization ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Warm Up ◽  
Lubricant Oil ◽  
Light Duty

The high viscosity of the lubricant oil in internal combustion engines at cold starts is responsible for poor friction reduction and inadequate thermal stabilization of metallic masses and represents a major bottleneck in the efforts to reduce specific fuel consumption and pollutant emissions. Consequently, the possibility of integrating techniques for proper thermal management of the lubricant oil on internal combustion engines is of utmost importance to both homologation and daily on-road operation. Main options for reducing the warm-up time for the engine lubricant are the upgrade of the engine cooling and lubricating circuits, dedicated heating, different flow management of the oil/coolant heat exchanger, a renewed design of the oil sump or a thermal storage section to increase the oil temperature in the early phases of the warm up. The paper presents a new opportunity, using a hot storage medium to heat up the oil in the early phase of a driving cycle. A certain quantity of hot water, so, is stored in a tank, which can be used to warm up the lubricating oil when the engine is started up. The heating of this service water can be done by using exhaust gas heat, which is always wasted in the atmosphere. The activity is realized on an IVECO 3.0 L light-duty diesel engine, during a transient cycle (NEDC) on a dynamometric test bench. The benefits in terms of both fuel consumption and CO2 emissions reduction. The characterization of the backpressure associated with an eventual additional heat exchangers and the more complex layout of the oil circuit is assessed, as well as the transient effects produced by the faster oil warm-up and oil-coolant interaction on the engine thermal stabilization.

Implementing variable valve actuation on a diesel engine at high-speed idle operation for improved aftertreatment warm-up

2019 ◽  
Vol 21 (7) ◽  
pp. 1134-1146
Author(s):  
Kalen R Vos ◽  
Gregory M Shaver ◽  
Mrunal C Joshi ◽  
James McCarthy
Keyword(s):  
Particulate Matter ◽  
High Speed ◽  
Exhaust Valve ◽  
Exhaust Gas ◽  
Warm Up ◽  
Aftertreatment System ◽  
Idle Speed ◽  
Variable Valve Actuation ◽  
Brake Mean Effective Pressure ◽  
Valve Opening

Aftertreatment thermal management is critical for regulating emissions in modern diesel engines. Elevated engine-out temperatures and mass flows are effective at increasing the temperature of an aftertreatment system to enable efficient emission reduction. In this effort, experiments and analysis demonstrated that increasing the idle speed, while maintaining the same idle load, enables improved aftertreatment “warm-up” performance with engine-out NOx and particulate matter levels no higher than a state-of-the-art thermal calibration at conventional idle operation (800 rpm and 1.3 bar brake mean effective pressure). Elevated idle speeds of 1000 and 1200 rpm, compared to conventional idle at 800 rpm, realized 31%–51% increase in exhaust flow and 25 °C–40 °C increase in engine-out temperature, respectively. This study also demonstrated additional engine-out temperature benefits at all three idle speeds considered (800, 1000, and 1200 rpm, without compromising the exhaust flow rates or emissions, by modulating the exhaust valve opening timing. Early exhaust valve opening realizes up to ~51% increase in exhaust flow and 50 °C increase in engine-out temperature relative to conventional idle operation by forcing the engine to work harder via an early blowdown of the exhaust gas. This early blowdown of exhaust gas also reduces the time available for particulate matter oxidization, effectively limiting the ability to elevate engine-out temperatures for the early exhaust valve opening strategy. Alternatively, late exhaust valve opening realizes up to ~51% increase in exhaust flow and 91 °C increase in engine-out temperature relative to conventional idle operation by forcing the engine to work harder to pump in-cylinder gases across a smaller exhaust valve opening. In short, this study demonstrates how increased idle speeds, and exhaust valve opening modulation, individually or combined, can be used to significantly increase the “warm-up” rate of an aftertreatment system.

scholarly journals Optimization of Inlet and Exhaust Manifold on a Single Cylinder Diesel Engine to Enhance the Combustion

2019 ◽  
Vol 8 (10) ◽  
pp. 1408-1411
Keyword(s):  
Diesel Engine ◽  
Direct Injection ◽  
Combustion Process ◽  
Fuel Mixture ◽  
Exhaust Valve ◽  
Intake Manifold ◽  
Power Stroke ◽  
Depth Of Cut ◽  
Exhaust Manifold ◽  
Single Cylinder

In the internal combustion Diesel engines the most important subsystem is Intake manifold and Exhaust manifold. In the intake manifold which supplies fresh air –fuel mixture in to the cylinders where combustion takes place at high temperature and high pressure. After exhaust gases scavenged through valves from the cylinders, these gases past exhaust manifold an outlet, through which the gases flow into exhaust pipes from there to the emission control equipment of engine which consists of catalytic and thermal converters. The development of swirl can be enhanced by re-designing of inlet port of an Engine. There is further development in the swirl due to combustion process to another maximum part way in to the power stroke. Swirl can promotes the combustion process in a better way and causes efficiency increase. Better mixing of air – fuel there is a little bit changing the inlet and exhaust valve. Valve stem diameter is 9.5mm, Inlet valve diameter is 36mm, Exhaust Valve diameter is 28mm by varying the pitch 1.0mm to 2mm and thread depth of cut as 4mm and three thread per inch from this arrangement to investigate the performance by enhancing the swirl of air flow to get betterment in the performance and decrease in emissions in a (DI) direct injection diesel engine with single cylinder when compared with normal engine.

scholarly journals Pengaruh perubahan sudut camshaft terhadap performa mesin sepeda motor sebagai upaya efisiensi energi

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Lukito Dwi Yuono ◽  
Eko Budiyanto
Keyword(s):  
Combustion Chamber ◽  
Fuel Consumption ◽  
Engine Performance ◽  
Exhaust Valve ◽  
Compression Pressure ◽  
A Value ◽  
Valve Opening ◽  
Motorcycle Engine

The role of the camshaft (noken as) is very important, including determining the time to open the valve, regulating the length of the valve opening duration, determining the overlap inlet and exhaust valve duration, as well as being a major component of the engine's working system. Modification of the camshaft angle is expected to be able to increase the efficiency of the combustion of fuel entering the combustion chamber and increase compression pressure in the combustion chamber so that it can improve volume quality of fuel entering the combustion chamber and can provide greater power to the engine rotation when in use. The purpose of this study was to determine the effect of camshaft angle changes on motorcycle engine performance and determine the effect of the camshaft duration on fuel consumption. The method that will be used in this research is to provide variations in angular changes on the camshaft of 20, 40, 60.Then test the dyno test on each variable. The result, the highest torque is the camshaft 40 variation with a value of 8.25 Nm. The highest power is in variation 40 with the highest number of 8.76 PS. Acceleration with the fastest time is obtained in camshaft 40 variations with a time of 14.2 seconds at a speed of 100 km/h. As well as the most efficient fuel consumption is at variation 20 with 150 ml fuel consumption.Keywords: Angle, camshaft, and engine performance.

Strategies for using valvetrain flexibility instead of exhaust manifold pressure modulation for diesel engine gas exchange and thermal management control

2019 ◽  
pp. 146808741988063 ◽  
Author(s):  
Kalen R Vos ◽  
Gregory M Shaver ◽  
Mrunal C Joshi ◽  
Aswin K Ramesh ◽  
James McCarthy
Keyword(s):  
Thermal Management ◽  
Pressure Control ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Valve Closure ◽  
Exhaust Manifold ◽  
Intake Valve ◽  
Cylinder Deactivation ◽  
Valve Opening ◽  
Gas Recirculation

At low-to-moderate loads, modern diesel engines manipulate exhaust manifold pressure to drive exhaust gas recirculation and thermally manage the aftertreatment. In these engines, exhaust manifold pressure control is typically achieved via either a valve after the turbine, a variable geometry turbine, or wastegating. The study described here demonstrates how valvetrain flexibility enables engine operation without requiring exhaust manifold pressure control. Specifically, intake valve closure modulation and cylinder deactivation at elevated engine speeds, along with exhaust valve opening modulation at low engine speeds, can match, or improve, efficiency and thermal management compared to a stock thermal calibration that requires exhaust manifold pressure control. During low-speed, low-load operation, the stock engine uses elevated exhaust manifold pressures to increase the required fueling (for thermal management) and to drive exhaust gas recirculation. Exhaust valve opening modulation can instead be implemented to enable similar aftertreatment warm-up, while cylinder deactivation allows aftertreatment temperature maintenance with a 40% reduction in fuel consumption. During high-speed, low-to-moderate loads, the stock engine implements thermal management operation by decreasing exhaust manifold pressure. Intake valve closure modulation together with cylinder deactivation can instead be implemented to enable fuel-efficient thermal management improvements via charge flow control.

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