BSFC Improvement Research Articles

Improvements of performance and emission characteristics of a diesel engine fueled with diesel/PODE3/n-butanol blended fuels by RSM-NSGA III in plateau environment

In order to reduce the pollutant emission and improve the performance characteristics, the RSM-NSGA III-TOPSIS optimization method was used to optimize a diesel engine fueled with different diesel/PODE3/n-butanol blended fuels in plateau environment. Firstly, a numerical model was developed and verified by the experimental results. An improved chemical reaction mechanism containing 164 species and 643 reactions was then employed to predict the combustion process. Secondly, a numerical model of the target parameters was obtained by using the Response Surface Method (RSM). Then, the mathematical model was optimized by Non-Dominated Sorting Genetic Algorithm III (NSGA III). Finally, the optimal solution was selected by Entropy Weight Method (EWM) and Technique for order preference by similarity to an ideal solution (TOPSIS). The optimized results showed a 5.14% improvement in BTE, a 52.12% decrease in soot, and a 20.6% improvement in BSFC compared with the original results at 2000 m. The optimized results showed a 11.9% improvement in BTE, a 37.7% decrease in soot, and a 0.5% improvement in BSFC compared with the original results at 4000 m. The results showed that the optimal solutions were different for different altitudes. Therefore, it is necessary to optimize the CI engine specifically for different altitudes.

Development of a virtual methodology based on physical and data-driven models to optimize engine calibration

Virtual engine calibration exploiting fully-physical plant models is the most promising solution for the reduction of time and cost of the traditional calibration process based on experimental testing. However, accuracy issues on the estimation of pollutant emissions are still unresolved. In this context, the paper shows how a virtual test rig can be built by combining a fully-physical engine model, featuring predictive combustion and NOx sub-models, with data-driven soot and particle number models. To this aim, a dedicated experimental campaign was carried out on a 1.6 liter EU6 diesel engine. A limited subset of the measured data was used to calibrate the predictive combustion and NOx sub-models. The measured data were also used to develop data-driven models to estimate soot and particulate emissions in terms of Filter Smoke Number (FSN) and Particle Number (PN), respectively. Inputs from engine calibration parameters (e.g., fuel injection timing and pressure) and combustion-related quantities computed by the physical model (e.g., combustion duration), were then merged. In this way, thanks to the combination of the two different datasets, the accuracy of the abovementioned models was improved by 20% for the FSN and 25% for the PN. The coupled physical and data-driven model was then used to optimize the engine calibration (fuel injection, air management) exploiting the Non-dominated Sorting genetic algorithm. The calibration obtained with the virtual methodology was then adopted on the engine test bench. A BSFC improvement of 10 g/kWh and a combustion reduction of 3.0 dB in comparison with the starting calibration was achieved.

Design, size estimation, and thermodynamic analysis of a realizable organic Rankine cycle system for waste heat recovery in commercial truck engines

The application of the ORC system for WHR in truck engines is a promising tool that minimizes the rate of CO2 released by the automobile industry and reduces specific fuel consumption by the sector. This article describes the development of a high-performance energy reuse module and size estimation for application in highway truck engines. The concept was performed on GT-Suite (vs. 2019) platform using R245fa as working fluid, and the evaluation of the module size was done using details from supplier specifications. Interestingly, the ORC system simulations were all performed at vehicle speeds of 66–119 km/hr to achieve realizable vehicle speed conditions. The modelling accomplished 2.99 kW of net power output, 3.27% BSFC improvement, and 6.36% ORC system efficiency, respectively. The ORC module's total estimated weight is approximately 100 kg, roughly giving a 32.3 kg/kW weight-to-power ratio.

Optimization of Diesel Engine Performance by Taguchi Grey Relational Analysis using Fuel Blends

In this present investigation an attempt was made to exp1ore the effect of fue1 injection timing (FIT), fue1 injection pressure (FIP), Load and exhaust gas recircu1ation (EGR) for various fue1 blends (Pa1m Oil, cotton Seed oi1, n-Butano1) as input parameters on SFC, BTE, CO, HC, NOx and with a minimum number of experiments. In order to reduce the experimenta1 efforts, Taguchi’s L27 orthogona1 array was emp1oyed for design of experiments. An a1gorithm invo1ving the combination of grey reationa1 ana1ysis with Taguchi technique was proposed for the optimization of engine emission and performance. The optimum combination for more brake therma1 efficiency is obtained for n-butanol-IT of 270 bTDC-IP of 200 bar- EGR of 10% load percentage of 100. At the same time optimum combination for minimum nitrogen oxide emission is obtained for CSO-IT of 190 bTDC-IP of 220 bar-EGR of 20 percentage- load percentage of 50. The optimum combination considering all the output parameters was obtained using grey relational analysis and output values for optimum combination was also calculated experimentally. Based on ANOVA, engine load be the most influencing factor (Contribution of load was 57.8 %) for the selected objective of improvement in BSFC and BTE with 1esser pena1ty on emissions (HC, CO, NOx) based on equal weight ages.

Enhancement in combustion, performance, and emission characteristics of a biodiesel-fueled diesel engine by using water emulsion and nanoadditive

The present study details the enhancement in combustion, performance, and emission characteristics of SB fueled diesel engine by using water emulsion (10% and 20%) and CNT nanoparticle (100 ppm). The biodiesel was prepared from soybean crude oil by trans-esterification process, and the fuel properties were measured. Experiments were performed in a single cylinder, four-stroke, and natural aspirated stationary diesel engine under varying BMEP conditions. The measured fuel properties of SB, 10WSB, and 100CNT10WSB are at par with standard limits, whereas 20WSB and 100CNT20WSB viscosity values are not par with standard limits. Studies in the engine revealed that the combustion starts later for water/biodiesel blends, and ICP, NHR, and RPR are higher compared to pure SB. The nanoparticle inclusion with emulsion fuels reduces the peak ICP and NHR values. Emulsion fuels show a good improvement in BSFC, BSEC, and EGT when compared to pure SB, and the nanoparticle inclusion further improves the performance parameters. The emission characteristics of test fuels show that the water/biodiesel blends have a lower magnitude of NOx and smoke emissions, and 10WSB shows better HC and CO emissions when compared to SB and 20WSB. An inclusion of CNT nanoparticle further reduces the emissions level.

Experimental investigations on the influence of compression ratio and piston crown geometry on the performance of biogas fuelled small spark ignition engine

The present research work is an attempt to develop a dedicated biogas fuelled SI engine technology from a 100 cc motor cycle. Such a small engine is coupled with alternator especially suitable in remote rural electrification which is still not connected to grid line or has a limited access. The experimental work presents the performance results of a small 98 cc, single-cylinder, four stroke cycle gasoline engine which is optimized to run on scrubbed biogas (CH4 93.8%) and raw biogas (CH4 56.6%) with successive modifications to the engine and its components. The work is carried out in stages to develop a dedicated biogas engine technology. The various aspects like piston crown geometry and compression ratio (CR), is investigated in this research work to evaluate the performances using biogas as fuel and comparing the same with gasoline is also made with the results obtained during experimental tests. The tests were conducted at 3000 rpm using three pistons having different crown geometries and cleavage on its crown. The selected three pistons enable to study the significance of CR (in the range of 6–9) and piston crown geometry to achieve the optimal configuration. The experimental results have revealed that increase in CR in a close range of 8:1 with larger cleavage on piston crown geometry enhances engine performance for Biogas fuelled small S.I. engine 100 cc category. It has been observed during comparative analysis that the maximum power produced by the biogas fuelled engine has improved by 13.4%, BSEC has increased by 23.30% and there is an 18.18% improvement in BSFC.

Cost Effective BS-VI Solution - A Combined Low Temperature Combustion and Conventional Diesel Combustion Concepts

<div class="section abstract"><div class="htmlview paragraph">Air pollution in India and also global warming are two major concern in the country. To address this situation, India is moving from BS-IV to BS-VI for on-road applications with 90% reduction in NOx and 50% in PM with limit on particulate number. Also moving to Trem-IV and Trem-V for off-road applications subsequently. It needs higher efficiency after-treatment systems like SCR and DPF to achieve such lower emission levels. Addition of these complex after-treatment system, severely increase the cost of diesel power plant with heavy penalty on fuel economy. Hence, it is challenge to auto industry to reduce the complexity and cost, so that it requires an alternate solution to reduce NOx and PM emissions at source to reduce cost and system complexity. Low Temperature Combustion (LTC) is a potential concept to reduce the NOx and PM emissions simultaneously. LTC concept was experimentally demonstrated on engines of passenger car and light commercial segments, but not much work carried out for heavy duty engines.</div><div class="htmlview paragraph">The current research work focused on development of LTC concept to reduce both NOx and PM emissions to a required low levels with fuel efficiency improvement so that aftertreatment system cost and complexity will be reduced to a great extent for BS-VI norms. Extensive simulation work carried out in this research for selecting the combustion system including fuel injection system (nozzle configuration, injection pressures and multiple injection), air handling system (air-fuel ratio, EGR%, and swirl) and piston bowl (combustion bowl geometry, compression ratio) suitable to run the engine on both LTC and conventional modes. Engine was built with all modified features and experiments were performed as per BS-VI cycles (WHSC and WHTC).</div><div class="htmlview paragraph">Experiments carried out over entire engine operating zone with smooth transition between LTC modes in part loads and conventional combustion mode in high load zone. Cycle engine out emissions reduced up to 2.1 g/kWh NOx and ~0.03 g/kWh PM with ~5% overall cycle BSFC improvement in steady state WHSC cycle. Encouraging results have been achieved on transient WHTC cycle also. The lowest BSFC noticed during experiments was close to 191 g/kWh at optimized engine out NOx levels. Utmost important is reduced engine out emissions and improved fuel economy which reduces after-treatment system cost & complexity, operating, maintenance cost and improved field performance with increased regeneration intervals. This result in lower urea and fuel consumption. In summary, LTC is a cost effective solution for BS-VI.</div></div>

Effective utilization of waste plastic oil in a direct injection diesel engine using high carbon alcohols as oxygenated additives for cleaner emissions

Waste plastic in municipal solid wastes degrade very slowly over several years and poses a serious challenge for sustainable environment. Hydrocarbons embodied in waste plastic could be converted into liquid fuel. Recycling waste plastic oil (WPO) in diesel engines offers a sustainable solution for ecological safety and energy security. However WPO produces carcinogenic smoke emissions in diesel engines that have to be controlled. This study attempts to minimize these emissions with the aid of oxygenated three high-carbon alcohols and also provides a comparative analysis on the effects of their addition to WPO individually on emissions and performance of a single cylinder diesel engine. A response surface methodology (RSM) based optimization using a 3-factor × 3-level full factorial experimental design was employed to find the optimum combination of exhaust gas recirculation (EGR), injection timing and alcohol with an objective to minimize NOx and smoke emissions with minimum BSFC. Three injection timings (21°, 23° and 25°CA bTDC) and three EGR rates (10, 20 and 30%) were used. Multiple regression models developed using RSM for NOx, smoke density and BSFC were found to be statistically significant. Interactive effects between injection timing and EGR on responses for all blends were compared. From desirability approach, WPO70P30 injected at 21° CA bTDC with 10% EGR delivered optimum emission and performance characteristics with a maximum desirability of 0.968. Pentanol was found to be the best among n-hexanol and n-octanol for this purpose. Confirmatory tests validated the models to be adequate with an error in prediction within 6%. With reference to diesel, n-pentanol with WPO injected at 21° CA bTDC with 10% EGR reduced smoke emissions by 76.8% and increased NOx emissions by 32% with an improvement in BSFC by 17.8%. With respect to neat WPO, the same blend reduced smoke emissions by 74.2% and increased NOx emissions by 9.7% with an improvement in BSFC by 3.2%.

EGR Systems Employment to Reduce the Fuel Consumption of a Downsized Turbocharged Engine at High-load Operations

In this work, a promising technique, consisting in an introduction of the external low pressure cooled EGR system, is analyzed by means of a 1D numerical approach with reference to a downsized spark-ignition turbocharged engine. The effects of various EGR amounts are investigated in terms of fuel consumption at full load operations. The proposed results highlight that EGR allows for increasing the knock safety margin. Fuel economy improvements however depend on the overall engine recalibration, consisting in proper settings of the A/F ratio and spark advance, compatible with knock occurrence. The numerical recalibration also accounts for additional limitations on the turbocharger speed, boost level, and turbine inlet temperature. The maximum BSFC improvement by the proposed solution is 5.9%.

A New De-throttling Concept in a Twin-Charged Gasoline Engine System

Throttling loss of downsized gasoline engines is significantly smaller than that of naturally aspirated counterparts. However, even under extremely downsizing condition, the downsized engine could still suffer a relatively large throttling loss when operating under part load. Various de-throttling concepts have been proposed recently, such as using a conventional turbine on the intake as a de-throttling mechanism or applying variable valve timing to control the charge airflow. Although they all can adjust the mass air flow without a throttle in regular use, an extra component or complicated control strategies have to be adopted. This paper will, for the first time, propose a de-throttling concept in a twin-charged gasoline engine with minimum modification of the existing system. The research engine model which this paper is based on is a 60% downsized 2.0L four cylinder gasoline demonstrator engine with both supercharger and turbocharger on the intake. The idea is to use a CVT controlled supercharger to ‘throttle’ the intake mass flow. By the adoption of a CVT, the supercharger outlet pressure could be controllable. Depending on whether the outlet pressure is larger than the inlet, the supercharger could supply boost at high load consuming engine power or behave like an expander under part load presenting a means to recover the throttling loss to provide all the necessary need. A 1-D simulation model was used for this research with the experimental data on the supercharger as an expander from the test rig. The results showed that at part load, by recovering some throttling loss through the supercharger, up to 5% BSFC improvement could be achieved compared to the throttled counterpart depending on the engine operating points. The effect of the reduced supercharger outlet temperature on the combustion efficiency was also discussed. It shows in the end that by the speed control, extended working range of the supercharger can be achievable which could push the fuel efficiency of the downsized engine further.

Development of 2-Stage Turbocharging Technology on a Medium Speed Diesel Engine

This study aims to investigate the potential of a 2-stage turbocharging system to reduce NOx emission. First, 1D cycle simulation model implementing high boost pressure, which imitates 2-stage turbocharging system, was calculated, and it was confirmed that with the combination of early intake valve closing, there is a potential to reduce NOx from conventional single turbocharging engine model without any fuel consumption penalty. Then, the 2-stage turbocharging system was coupled to a medium speed 6-cylinder experimental diesel engine, and test runs were carried out to confirm the potential. Results of the test run show that 2-stage turbocharging system has the potential to reduce NOx as estimated, and as a co-product, BSFC improvement was confirmed when allowing Tier II level NOx emission. Furthermore, engine output increment was possible, without deteriorating BSFC-NOx trade-off relationship. Further development is planned to meet IMO NOx Tier III regulation.

Steady State Engine Test Demonstration of Performance Improvement With an Advanced Turbocharger

Heavy EGR required on diesel engines for future emission regulation compliance has posed a big challenge to conventional turbocharger technology for high efficiency and wide operation range. This study, as part of the U.S. Department of Energy sponsored research program, is focused on advanced turbocharger technologies that can improve turbocharger efficiency on customer driving cycles while extending the operation range significantly, compared to a production turbocharger. The production turbocharger for a medium-duty truck application was selected as a donor turbo. Design optimizations were focused on the compressor impeller and turbine wheel. On the compressor side, advanced impeller design with arbitrary surface can improve the efficiency and surge margin at the low end while extending the flow capacity, while a so-called active casing treatment can provide additional operation range extension without compromising compressor efficiency. On the turbine side, mixed flow turbine technology was revisited with renewed interest due to its performance characteristics, i.e., high efficiency at low-speed ratio, relative to the base conventional radial flow turbine, which is relevant to heavy EGR operation for future diesel applications. The engine dynamometer test shows that the advanced turbocharger technology enables over 3% BSFC improvement at part-load as well as full-load condition, in addition to an increase in rated power. The performance improvement demonstrated on an engine dynamometer seems to be more than what would typically be translated from the turbocharger flow bench data, indicating that mixed flow turbine may provide additional performance benefits under pulsed exhaust flow on an internal combustion engine and in the low-speed ratio areas that are typically not covered by steady state flow bench tests.

Simulation of a heavy-duty diesel engine with electrical turbocompounding system using operating charts for turbocharger components and power turbine

In diesel engines, approximately 30–40% of the energy supplied by the fuel is rejected to the ambience through exhaust gases. Therefore, there is a potentiality for further considerable increase of diesel engine efficiency with the utilization of exhaust gas heat and its conversion to mechanical or electrical energy. In the present study, the operational behavior of a heavy-duty (HD) diesel truck engine equipped with an electric turbocompounding system is examined on a theoretical basis. The electrical turbocompounding configuration comprised of a power turbine coupled to an electric generator, which is installed downstream to the turbocharger (T/C) turbine. A diesel engine simulation model has been developed using operating charts for both turbocharger and power turbine. A method for introducing the operating charts into the engine model is described thoroughly. A parametric analysis is conducted with the developed simulation tool, where the varying parameter is the rotational speed of power turbine shaft. In this study, the interaction between the power turbine and the turbocharged diesel engine is examined in detail. The effect of power turbine speed on T/C components efficiencies, power turbine efficiency, exhaust pressure and temperature, engine boost pressure and air to fuel ratio is evaluated. In addition, theoretical results for the potential impact of electrical turbocompounding on the generated electric power, net engine power and relative improvement of brake specific fuel consumption (bsfc) are provided. The critical evaluation of the theoretical findings led to the basic conclusion that there is a significant potential for bsfc improvement of HD diesel truck engines with the proposed electrical turbocompounding concept, which reaches up to 4% at full engine load. The improvement of bsfc with electric turbocompounding appears to be more attractive solution in terms of technical complexity and installation cost against other competitive heat recovery technologies such as Rankine cycle systems.

BSFC Improvement by Diesel-Rankine Combined Cycle in the High EGR Rate and High Boosted Diesel Engine

BSFC Improvement by Diesel-Rankine Combined Cycle in the High EGR Rate and High Boosted Diesel Engine

Study of available exhaust gas heat recovery technologies for HD diesel engine applications

Diesel engines reject a considerable amount of energy to the ambience through the exhaust gas. Significant reduction of engine brake-specific fuel consumption (bsfc) could be attained by recovering a significant part of exhaust gas heat. Various techniques have been proposed in the past to recover exhaust energy: mechanical, electrical turbocompounding and Rankine Bottoming Cycles. In the present it is examined the potential bsfc improvement of heavy-duty (HD) diesel engines using the aforementioned technologies. The analysis is performed on a HD Diesel engine. An engine simulation model is used to estimate exhaust gas characteristics and examine mechanical and electrical turbocompounding. For mechanical turbocompounding it is investigated the effect of power turbine pressure ratio and efficiency while for electric the effect of T/C efficiency and exhaust pressure increase. Finally, a parametric study has been conducted using a 'Rankine bottoming cycle'. The analysis includes the effect of evaporator pressure and expander efficiency.