scholarly journals Exploring alternative combustion control strategies for low-load exhaust gas temperature management of a heavy-duty diesel engine

2018 ◽  
Vol 20 (4) ◽  
pp. 381-392 ◽  
Author(s):  
Wei Guan ◽  
Hua Zhao ◽  
Zhibo Ban ◽  
Tiejian Lin
Keyword(s):  
Fuel Consumption ◽  
Control Strategies ◽  
Fuel Efficiency ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Valve Closure ◽  
Intake Valve ◽  
Gas Temperature ◽  
Exhaust Gas Temperature ◽  
Gas Recirculation

The employment of aftertreatment systems in modern diesel engines has become indispensable to meet the stringent emissions regulations. However, a minimum exhaust gas temperature of approximately 200 °C must be reached to initiate the emissions control operations. Low-load engine operations usually result in relatively low exhaust gas temperature, which lead to reduced or no exhaust emissions conversion. In this context, this study investigated the use of different combustion control strategies to explore the trade-off between exhaust gas temperature, fuel efficiency, and exhaust emissions. The experiments were performed on a single-cylinder heavy-duty diesel engine at a light load of 2.2 bar indicated mean effective pressure. Strategies including the late intake valve closing timing, intake throttling, late injection timing (Tinj), lower injection pressure (Pinj), and internal exhaust gas recirculation and external exhaust gas recirculation were investigated. The results showed that the use of external exhaust gas recirculation and lower Pinj was not effective in increasing exhaust gas temperature. Although the use of late Tinj could result in higher exhaust gas temperature, the delayed combustion phase led to the highest fuel efficiency penalty. Intake throttling and internal exhaust gas recirculation allowed for an increase in exhaust gas temperature at the expense of higher fuel consumption. In comparison, late intake valve closure strategy achieved the best trade-off between exhaust gas temperature and net indicated specific fuel consumption, increasing the exhaust gas temperature by 52 °C and the fuel consumption penalty by 5.3% while reducing nitrogen oxide and soot emissions simultaneously. When the intake valve closing timing was delayed to after −107 crank angle degree after top dead centre, however, the combustion efficiency deteriorated and the HC and CO emissions were significantly increased. This could be overcome by combining internal exhaust gas recirculation with late intake valve closure to increase the in-cylinder combustion temperature for a more complete combustion. The results demonstrated that the ‘late intake valve closure + internal exhaust gas recirculation’ strategy can be the most effective means, increasing the exhaust gas temperature by 62 °C with 4.6% fuel consumption penalty. Meanwhile, maintaining high combustion efficiency as well as low HC and CO emissions of diesel engines.

scholarly journals Miller cycle combined with exhaust gas recirculation and post–fuel injection for emissions and exhaust gas temperature control of a heavy-duty diesel engine

2019 ◽  
Vol 21 (8) ◽  
pp. 1381-1397 ◽  
Author(s):  
Wei Guan ◽  
Vinícius B Pedrozo ◽  
Hua Zhao ◽  
Zhibo Ban ◽  
Tiejian Lin
Keyword(s):  
Control Strategies ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Post Injection ◽  
Miller Cycle ◽  
Gas Temperature ◽  
Heavy Duty Diesel ◽  
Exhaust Gas Temperature ◽  
Gas Recirculation ◽  
Total Fluid

Miller cycle has been shown as a promising engine strategy to reduce in-cylinder nitrogen oxide (NOx) formation during the combustion process and facilitate its removal in the aftertreatment systems by increasing the exhaust gas temperature. However, the level of NOx reduction and the increase in exhaust gas temperature achieved by Miller cycle alone is limited. Therefore, research was carried out to investigate the combined use of Miller cycle with other advanced combustion control strategies in order to minimise the NOx emissions and the total cost of ownership. In this article, the effects of Miller cycle, exhaust gas recirculation, and post-injection were studied and analysed on the performance and exhaust emissions of a single cylinder heavy-duty diesel engine. A cost–benefit analysis was carried out using the corrected total fluid efficiency, which includes the estimated urea solution consumption in the NOx aftertreatment system as well as the fuel consumption. The experiments were performed at a low load of 6 bar net indicated mean effective pressure. The results showed that the application of a Miller cycle–only strategy with a retarded intake valve closing at −95 crank angle degree after top dead centre decreased NOx emissions by 21% to 6.0 g/kW h and increased exhaust gas temperature by 30% to 633 K when compared to the baseline engine operation. This was attributed to a reduction in compressed gas temperature by the lower effective compression ratio and the in-cylinder mass trapped due to the retarded intake valve closing. These improvements, however, were accompanied by a fuel-efficiency penalty of 1%. A further reduction in the level of NOx from 6.0 to 3.0 g/kW h was achieved through the addition of exhaust gas recirculation, but soot emissions were more than doubled to 0.022 g/kW h. The introduction of a post-injection was found to counteract this effect, resulting in simultaneous low NOx and soot emissions of 2.5 and 0.012 g/kW h, respectively. When taking into account the urea consumption, the combined use of Miller cycle, exhaust gas recirculation, and post-injection combustion control strategies were found to have relatively higher corrected total fluid efficiency than the baseline case. Thus, the combined ‘Miller cycle + exhaust gas recirculation + post-injection’ strategy was the most effective means of achieving simultaneous low exhaust emissions, high exhaust gas temperature, and increased corrected total fluid efficiency.

Reduction in Exhaust Gas Temperature of Biodiesel Fueled Engine by Exhaust Gas Recirculation

2008 ◽  
Vol 36 (12) ◽  
pp. 978-983 ◽  
Author(s):  
Arumugam Sakunthalai Ramadhas ◽  
Chandrasekaran Muraleedharan ◽  
Simon Jayaraj
Keyword(s):  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Exhaust Gas Temperature ◽  
Gas Recirculation

Performance Evaluation of EGR in Two Stroke I.C. Engine

2015 ◽  
Vol 812 ◽  
pp. 60-63
Author(s):  
V. Ramakrishnan ◽  
R. Thamilarasan ◽  
K. Purushothaman
Keyword(s):  
Low Cost ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Engine Cylinder ◽  
Pass Through ◽  
Exhaust Gas Temperature ◽  
Gas Recirculation ◽  
Stroke Engine ◽  
Fresh Charge

Petrol engines are known for their simplicity, low cost and maintenance. However nowadays use of two stroke petrol engines are fading away from the market. An attempt has been made here to revive the use of these old engines by using Exhaust Gas Recirculation (EGR) to improve performances.Short circuiting of fresh charge is an important contributing factor for reduction in performance in two stroke engines. Our project is aimed to reduce short circuiting of fresh charge by admitting cooled exhaust gas to pass through reed valves fitted at the upper end of the transfer passage, in a crank case scavenged two stroke engine. Reed valves were provided at the upper end of the transfer passage using a flange arrangement. Exhaust gas temperature at around 4000 was cooled using a heat exchanger to avoid pre-ignition inside the engine cylinder. The performance of the engine is tested using eddy current dynamometer. The study indicates an appreciable decrease in specific fuel consumption and in HC/CO emissions in a crank case scavenged two stroke engine.

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.

Improving diesel engine efficiency at high speeds and loads through improved breathing via delayed intake valve closure timing

2017 ◽  
Vol 20 (2) ◽  
pp. 194-202 ◽  
Author(s):  
Kalen R Vos ◽  
Gregory M Shaver ◽  
Xueting Lu ◽  
Cody M Allen ◽  
James McCarthy ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Exhaust Gas ◽  
Valve Closure ◽  
Effective Pressure ◽  
Intake Valve ◽  
Brake Mean Effective Pressure ◽  
Gas Recirculation

Valve train flexibility enables optimization of the cylinder-manifold gas exchange process across an engine’s torque/speed operating space. This study focuses on the diesel engine fuel economy improvements possible through delayed intake valve closure timing as a means to improve volumetric efficiency at elevated engine speeds via dynamic charging. It is experimentally and analytically demonstrated that intake valve modulation can be employed at high-speed (2200 r/min) and medium-to-high load conditions (12.7 and 7.6 bar brake mean effective pressure) to increase volumetric efficiency. The resulting increase in inducted charge enables higher exhaust gas recirculation fractions without penalizing the air-to-fuel ratio. Higher exhaust gas recirculation fractions allow efficiency improving injection advances without sacrificing NOx. Fuel savings of 1.2% and 1.9% are experimentally demonstrated at 2200 r/min for 12.7 and 7.6 bar brake mean effective pressure operating conditions via this combined strategy of delayed intake valve closure, higher exhaust gas recirculation fractions, and earlier injections.

scholarly journals Ensuring Requirements for Emissions of Harmful Substances of Diesel Engines

2020 ◽  
Vol 19 (4) ◽  
pp. 305-310
Author(s):  
G. M. Kuharonak ◽  
D. V. Kapskiy ◽  
V. I. Berezun
Keyword(s):  
Diesel Engine ◽  
Nitrogen Oxides ◽  
Fuel Consumption ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Average Temperature ◽  
Dispersed Particles ◽  
Harmful Substances ◽  
Gas Recirculation ◽  
Emissions Of Harmful Substances

The purpose of this work is to consider the requirements for emissions of harmful substances of diesel engines by selecting design and adjustment parameters that determine the organization of the workflow, and the exhaust gas cleaning system, taking into account the reduction of fuel consumption. Design elements and geometric characteristics of structures for a turbocharged diesel engine of Д-245 series produced by JSC HMC Minsk Motor Plant (4ЧН11/12.5) with a capacity of 90 kW equipped with an electronically controlled battery fuel injection have been developed: exhaust gas recirculation along the high pressure circuit, shape and dimensions of the combustion chamber, the number and angular arrangement of the nozzle openings in a nozzle atomizer, and inlet channels of the cylinder head. Methods for organizing a workflow are proposed that take into account the shape of the indicator diagrams and affect the emissions of nitrogen oxides and dispersed particles differently. Their implementation allows us to determine the boundary ranges of changes in the control parameters of the fuel supply and exhaust gas recirculation systems when determining the area of minimizing the specific effective fuel consumption and the range of studies for the environmental performance of a diesel engine. The paper presents results of the study on the ways to meet  the requirements for emissions of harmful substances, obtained by considering options for the organization of working processes, taking into account the reduction in specific effective fuel consumption, changes in the average temperature of the exhaust gases and diesel equipment. To evaluate these methods, the following indicators have been identified: changes in specific fuel consumption and average temperature of the toxicity cycle relative to the base cycle, the necessary degree of conversion of the purification system for dispersed particles and NOx. Recommendations are given on choosing a diesel engine to meet Stage 4 emission standards for nitrogen oxides and dispersed particles.

Emission reduction through internal and low-pressure loop exhaust gas recirculation configuration with negative valve overlap and late intake valve closing strategy in a compression ignition engine

2017 ◽  
Vol 18 (10) ◽  
pp. 973-990 ◽  
Author(s):  
Jaeheun Kim ◽  
Choongsik Bae
Keyword(s):  
High Pressure ◽  
Nitrogen Oxides ◽  
Exhaust Gas Recirculation ◽  
Low Pressure ◽  
Exhaust Gas ◽  
Effective Pressure ◽  
Intake Valve ◽  
Trade Off ◽  
Indicated Mean Effective Pressure ◽  
Gas Recirculation

An investigation was carried out to examine the feasibility of replacing the conventional high-pressure loop/low-pressure loop exhaust gas recirculation with a combination of internal and low-pressure loop exhaust gas recirculation. The main objective of this alternative exhaust gas recirculation path configuration is to extend the limits of the late intake valve closing strategy, without the concern of backpressure caused by the high-pressure loop exhaust gas recirculation. The late intake valve closing strategy improved the conventional trade-off relation between nitrogen oxides and smoke emissions. The gross indicated mean effective pressure was maintained at a similar level, as long as the intake boosting pressure kept changing with respect to the intake valve closing timing. Applying the high-pressure loop exhaust gas recirculation in the boosted conditions yielded concern of the exhaust backpressure increase. The presence of high-pressure loop exhaust gas recirculation limited further intake valve closing retardation when the negative effect of increased pumping work cancelled out the positive effect of improving the emissions’ trade-off. Replacing high-pressure loop exhaust gas recirculation with internal exhaust gas recirculation reduced the burden of such exhaust backpressure and the pumping loss. However, a simple feasibility analysis indicated that a high-efficiency turbocharger was required to make the pumping work close to zero. The internal exhaust gas recirculation strategy was able to control the nitrogen oxides emissions at a low level with much lower O2 concentration, even though the initial in-cylinder temperature was high due to hot residual gas. Retardation of intake valve closing timing and intake boosting contributed to increasing the charge density; therefore, the smoke emission reduced due to the higher air–fuel ratio value exceeding 25. The combination of internal and low pressure loop loop exhaust gas recirculation with late intake valve closing strategy exhibited an improvement on the trade-off relation between nitrogen oxides and smoke emissions, while maintaining the gross indicated mean effective pressure at a comparable level with that of the high-pressure loop exhaust gas recirculation configuration.

scholarly journals ЗАСТОСУВАННЯ ГАЗОДИНАМІЧНОГО ОХОЛОДЖЕННЯ В СИСТЕМАХ РЕЦИРКУЛЯЦІЇ ВІДХІДНИХ ГАЗІВ СУДНОВИХ ДИЗЕЛІВ

2019 ◽  
pp. 81-86
Author(s):  
Дмитро Вікторович Коновалов
Keyword(s):  
Fuel Consumption ◽  
Exhaust Gas Recirculation ◽  
Back Pressure ◽  
Specific Fuel Consumption ◽  
Design Solution ◽  
Exhaust Gas ◽  
Engine Fuel ◽  
Gas Dynamics Equations ◽  
Exhaust Gases ◽  
Gas Recirculation

There are many ways and methods to reduce exhaust gases emissions on modern ships. One of the most effective ways to reduce NOx and SOx emissions is to use of exhaust gas recirculation (EGR technology). The EGR system disadvantage is an increase in back pressure through additional pressure losses in the scrubber and heat ex-changer, which entails an engine fuel efficiency deterioration. Creating a reliable and efficient heat exchanger for cooling recirculation gases is a complex task due to deposits and pollution emitted by these gases. In the pre-sent work, the jet apparatus effectiveness named aerothermopressor is analyzed in the scheme with exhaust gases recirculation of the ship low-speed two-stroke engine. Aerothermopressor is a two-phase jet for contact disperse cooling, in which by increasing the heat from the gas stream the gas pressure and cooling are increased. The calculation of the characteristics of the engine was carried out, both in nominal, and in operating modes and in all possible range of partial loads. The installation of the aerothermopressor before the scrubber is pro-posed, which allows reducing engine thermal load. Increasing the pressure in the aerothermopressor by 0.2-0.4 ∙ 105 Pa (6-12 %) allows reducing the back pressure in the gas exhaust system and thus reducing the load on the exhaust gas recirculation fan and when the engine load is higher than 75% in the cold zone, the fan is not need-ed, which additionally allows to reduce the specific fuel consumption. The parameters of the exhaust gases that are going to be recirculated and the processes of their gas-dynamic cooling in the aerothermopressor are based on the developed technique and program using the thermodynamic and gas dynamics equations. The proposed scheme-design solution allows at a high environmental friendliness of the existing exhaust gas recirculation sys-tem to provide a certain reduction in specific fuel consumption. It was determined that the engine specific fuel consumption has been decreasing when the aerothermopressor is used to Dge = 2.5-3.0 g/(kW·h) (1.5-1.7%).

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