Deterioration Of Emissions Research Articles

Gasoline and diesel passenger car emissions deterioration using on-road emission measurements and measured mileage

Modern gasoline and diesel vehicles are equipped with highly effective emission control systems that result in low emissions of pollutants such as nitrogen oxides (NO x ) when new. However, with increasing age or mileage, the emissions performance of vehicles can deteriorate over time, leading to increased emissions. In this work we use comprehensive vehicle emission remote sensing measurements collected over a wide range of conditions, together with individual vehicle measured mileage to quantify vehicle emissions deterioration. A quantile regression modelling approach is used to provide a more complete understanding of the distribution of deterioration effects that is not captured by considering mean changes over time. The approach accounts for factors such as driving conditions and ambient temperature, as well as determining whether deterioration affects whole populations of vehicles or a smaller subset of them. Accounting for these factors, we find that for most pollutants the rate of deterioration of emissions from pre-Euro 5 gasoline passenger cars is highly skewed. Between 5% and 10% of pre-Euro 5 gasoline passenger cars have emissions similar to a Euro 5 diesel car, suggesting that policies should be developed to accelerate their removal from the fleet. Furthermore, we find evidence that there are differences between vehicle manufacturers in the way emissions of NO x deteriorate. • 197,000 vehicle emission remote sensing measurements coupled with individual measured mileage data from vehicle inspections. • Quantile regression framework used to examine distribution of deterioration effects of passenger car NO x and PM emissions. • Rate of deterioration for gasoline NO x emission controlled by small proportion of vehicles. • Large fleet coverage of remote sensing is exploited to examine manufacturer-specific NO x emission deterioration.

Study of durability of diesel vehicle emissions performance based on real driving emission measurement

Diesel vehicle emissions generally deteriorate with vehicle mileage due to the wear and deterioration of vehicle parts. Most of the experimental studies on vehicle emission durability were carried out based on the standard operation cycles of engine or vehicle, few research investigated vehicle emission deterioration characteristics under real driving conditions. In this research, the real driving emission (RDE) test method was used to investigate and evaluate the emission deterioration characteristics of two China-V diesel vehicles equipped with DOC and SCR systems. The experimental results show the emissions of CO and NOx from the N2 and N3 diesel vehicles increase with the vehicle mileage, showing the tendency of emission deterioration. The calculated deterioration factors of N2 and N3 diesel vehicle CO and NOx emissions are greater than the recommended values in China standard HJ 438–2008, which means experimental study on the vehicle emissions durability is necessary. The vehicle emissions deterioration depends on real driving conditions and the vehicle usage over vehicle lifetime.

Engineered nanocomposites in asphalt binders

Abstract Recently, nanotechnology has been effectively used in the field of road pavement. Oxidation and aging of asphalt cause deterioration of road pavements and increase asphalt-related emissions. We propose an anti-aging strategy to interrupt the asphalt deterioration by using engineered clay/fumed silica nanocomposites. In this research, the morphological, chemical, thermal, mechanical, and rheological properties of nano-modified asphalt binders are meticulously analyzed in various conditions. The experiment results proved that this composite efficiently disrupts the chemical oxidation and decomposition in the mixture and reduces the aging rate. Remarkably, asphalt binder rheology experiments revealed that the addition of 0.2–0.3 wt% of nano-reinforced materials maximized their rheological resistance after short- and long-term aging. Moreover, nanoparticles improve the moisture resistance efficiency and in turn overcome the critical issue of moisture in low production temperature within the framework of warm mix asphalt technology. This cost-effective, facile, and scalable approach in warm mix asphalt mixtures can contribute to increased sustainability and lifespan of pavements and a reduction in greenhouse gas emissions.

Utah Wintertime Measurements of Heavy-Duty Vehicle Nitrogen Oxide Emission Factors.

There have only been a few wintertime studies of heavy-duty vehicle (HDV) NOx emissions in the United States, and while they have observed increased emissions, fleet characterization to identify the cause has been lacking. We have collected wintertime measurements of NOx emission factors from 1591 HDVs at a Utah Port of Entry in December 2020 that includes individual vehicle identification. In general, NOx emission factors for 2011 and newer chassis model year HDV are significantly higher than those for 2017 spring measurements from California. The newest chassis model year HDV (2017-2021) NOx emission factors are similar, indicating no significant emission deterioration over the 5 year period, though they are still approximately a factor of 3 higher than the portable emission measurement on-road enforcement standard. We estimate that ambient temperature increases NOx emissions no more than 25% in the newer HDV, likely through reductions in catalyst efficiencies. NOx emissions increase to a significantly higher level for the 2011-2013 chassis model year vehicles, where within the uncertainties, they have emissions similar to older precontrol vehicles, indicating that they have lost their NOx control capabilities within 8 years. MOVES3 modeling of the Utah fleet underpredicted mean NOx emissions by a factor of 1.8 but the MOVES3 estimate is helped by including a larger fraction of high-emitting glider kit trucks (new chassis with pre-emission control engines) than found in the observations.

Experimental study on the high load extension of PODE/methanol RCCI combustion mode with optimized injection strategy

The polyoxymethylene dimethyl ethers (PODE)/methanol reactivity controlled compression ignition (RCCI) mode was realized by direct injection of PODE as high-reactivity fuel to ignite pre-mixed methanol as low-reactivity fuel in a high-pressure common-rail diesel engine. The effects of load extension ratio (LER) on in-cylinder combustion, emission characteristics and fuel economy of RCCI engine were investigated, and the influences of PODE injection strategy on the high-load extension of PODE/methanol RCCI mode were also systematically studied, including the start of main-injection (SOImain), start of pilot-injection (SOIpilot) and pilot-injection quantity (PIQ). The results show that with the increase of LER, the peak values of in-cylinder pressure and heat release rate of RCCI mode increase, the brake thermal efficiency (BTE) and the hydrocarbons (HC), carbon monoxide (CO) and unregulated emissions also increase, but the increase of the ringing intensity (RI), the coefficient of variation of IMEP (COVIMEP) and nitrogen oxides (NOx) limit the further increase of LER. The delay of SOImain can effectively reduce RI, but it will lead to the deterioration of CO and HC emissions and fuel economy. The pilot-injection strategy can weaken the trade-off relationship between NOx and soot emissions and improve combustion stability. With the advance of SOIpilot, the RCCI combustion process evolves from two-stage heat release to single-stage heat release, and the emissions of HC, CO, NOx and soot are reduced. With the increase of PIQ, the combustion phase of PODE/methanol RCCI mode advances, and the RI, COVIMEP and IMEP increase. At 59.5 mg/cycle condition, when PIQ is increased from 2 mg to 10 mg, CO and HC emissions decrease by 19.57% and 6.97% respectively, while NOx emissions increase by 7.93%. With the appropriate LER combined with the optimized PODE injection strategy, the BTE of PODE/methanol RCCI engine reaches 48.68%, and the IMEP is extended from 0.77 MPa to 1.08 MPa.

Environmental analysis of the traffic closure on Piotrowo and Berdychowo streets in Poznań

The article deals with the ecological assessment of the potential road investment, which is the closure of Piotrowo and Berdychowo streets within the campus of the Poznań University of Technology. The research was carried out on a simulation model of the city of Poznań with the use of the PTV software. Research has shown that the closure of these streets has virtually no impact on city wide emissions. However, the emissions deterioration takes place on a local scale, i.e. in the vicinity of the campus of the Poznań University of Technology and on most of the streets leading to it.

Research on a China 6b heavy-duty diesel vehicle real-world engine out NOx emission deterioration and ambient correction using big data approach.

China VI standard proposed higher requirements for durability of heavy-duty diesel vehicles emissions. Previous research which took advantages of both on-board sensors and big data approach to get the NOx deterioration factor was rather scarce. This paper used big data approach to study the deterioration of engine out NOx emission based on 254,622 km operation data getting from the on-board sensors or ECUs (Electronic Control Unit). Meanwhile, a formula for on-board NOx correction for ambient humidity and temperature had been fitted. The analyses revealed that the engine out NOx deterioration factor (DF) of the maximum weight steady-state condition was about 1.005 after 254,622 km durability test; as for transient conditions, the DF was not more than 1.092 during 254,622 km durability test. For a same steady working condition, the engine out NOx mass flow (g/h) was negatively linearly correlated with absolute humidity (Ha) (R2 = 0.997). If Ha was lower than 12 g/kg, Ha almost had no effect on engine out NOx concentration (ppm). Otherwise, there was also a negatively linear relationship between them (R2 = 0.978). It is hoped that the methods and conclusions of this paper could provide some enlightenment for future NOx emission deterioration research.

Is carbon neutrality feasible for Korean manufacturing firms?: The CO2 emissions performance of the Metafrontier Malmquist–Luenberger index

To achieve carbon neutrality, the Korean government has promoted regulatory policies on the transition toward a carbon free economy in 2050. Unfortunately, these policies face strong complaints from industries with respect to losing international competitiveness owing to extra cost burdens. Is it feasible to achieve a carbon neutral economy with these regulatory policies? This study tries answering the question by evaluating the CO2 emissions performances of the Korean manufacturing industry for feasible solutions toward a carbon neutral economy. For this purpose, we adopted the metafrontier Malmquist–Luenberger (MML) index to reflect group heterogeneity at the technology level. Forty subsectors of manufacturing industrial data were collected from 2012 to 2017, which were classified under four technological levels: high, middle-high, middle-low, and low. The CO2 emissions performance showed a poor effect from the policies, with an overall 0.8% deterioration (−0.8%) in the CO2 emissions. Under the group heterogeneity, the middle-high and middle-low technology groups showed a significantly slower upward trend, implying that the environmental regulatory regime did not have a strong effect on these groups. To obtain a feasible solution for this fine tuning, MML decomposition was implemented in the second stage. As the efficiency change is the main driver that influences the CO2 emissions performance, the Korean government should encourage the catching-up effect in industries via a green cultural revolution, as well as provide strong incentives to avoid negligible performance in the innovation effect, supported by more market-oriented emissions trading schemes (ETSs).

Does California’s EMFAC2017 vehicle emissions model underpredict California light-duty gasoline vehicle NO x emissions?

ABSTRACT On-road remote sensing measurements of light and medium-duty gasoline vehicles collected within California’s South Coast Air Basin since 1999 generally fall within the range of observed summer ambient molar NO x /CO measurements collected during morning rush hours. Compared with ambient and on-road emissions, the California Air Resources Board EMFAC model underpredicts 2018 gasoline vehicle NO x emission factors by more than a factor of 2.6. Contributing to these differences is that vehicles older than model year 2006 have NO x emission deterioration rates that are up to four times higher on-road than predicted by the EMFAC model. A fuel-based inventory using the 2018 on-road gasoline emission factors for CO and NOx results in total CO emissions similar to the basin inventory but NOx emissions that are 74% higher than the inventory. The higher NO x emission estimates from on-road gasoline vehicle measurements make their contribution to the inventory slightly larger than heavy-duty diesel vehicles. We have found LEV I (1994–2003) gasoline vehicles are a major source of these on-road emissions and that significant NOx reductions in the South Coast Air Basin are being overlooked by not targeting the high emitters for removal. Implications: A comparison of ambient and on-road vehicle molar NOx/CO ratios collected in California’s South Coast Air Basin with those predicted by California’s EMFAC2017 vehicle emissions model shows that the model significantly underpredicts NOx emission factors for gasoline vehicles. This results in a 74% underestimate of the contribution of gasoline vehicles to the basin’s NOx inventory, with the contribution from gasoline vehicles comparable to that from heavy-duty diesel trucks. This likely means that current projections for future NOx emission reductions from mobile sources in the basin will not be realized unless additional NOx reductions are obtained from older gasoline vehicles.

Experimental study on the emission influence of the fuel system faults for light-duty vehicle

The fuel system is a very important system in light-duty vehicles. The faults of the system will cause serious deterioration of vehicle emissions and other performance. In order to study the influence of different types of faults on emissions, this paper studies the faults of several OBDII vehicles. The results show that: the fault of rich mixture in fuel system will increase the emissions of CO and NMHC by 3-5 times and the emissions of NOx by 1-2 times; the fault of lean mixture in fuel system will increase the emissions of NOx by 4-5 times and the emissions of CO and NMHC by 0.7-2.5 times; there are two kinds of imbalance faults, one is imbalance lean and the other is imbalance rich. Imbalance lean mainly causes NOx deterioration, which is increased by 7.5 times. Imbalance rich mainly causes CO and NMHC emissions deterioration, which is increased by about 3 times. There are many kinds of faults in the fuel system which cause serious deterioration of emissions. It is necessary to focus on monitoring the faults of the fuel system.

Influence and strategy optimization of fuel injection timing on PN and fuel consumption

During the development of a CN Ⅵ light vehicle equipped with a GDI gasoline engine, the phenomenon of high PN appeared. In response to the operating conditions of the engine running in the WLTC cycle, a corresponding SOI sweep was performed on the dyno bench. The PN emissions of the engine has reduced by optimizing of SOI. The results show that when the SOI is sufficiently advanced, the oil film formed by the collision of the spray and the piston causes the PN emissions to increase significantly. In order to avoid the deterioration of the PN emissions, the SOI should be appropriately postponed. In the low load conditions, it is more appropriate to calibrate the SOI at 295°CA and 290°CA. In the medium speed area, it is more suitable to set it at 300°CA or later. The SOI in the higher speed area can be slightly advanced if necessary. And the impact of SOI on fuel consumption is more obvious at low speeds, but it is not obvious at the conditions of medium to high loads and speeds.

Eco-adaptive cruise control of diesel commercial vehicle in the intelligent network environment

Abstract Vehicle intelligent network is a huge interactive network composed of vehicle location, speed and trajectory information. Vehicle can collect surrounding environment information and send its own information through the vehicle intelligent network. These widely advanced information can be analyzed and processed, timely report road conditions, arrange traffic lights phase, so as to optimize the best trajectory for different vehicles. Commercial vehicle accounts for a large proportion of road fuel consumption and emissions, which combined with the intelligent network can be reduced a lot. Therefore, for the integrated control of fuel consumption and emission of commercial vehicle in the intelligent network environment, proposing environment friendly adaptive cruise control (eco friendly ACC) which can provides real time suggestions for vehicle driving, such as slow acceleration, smooth driving, etc. to reduce fuel consumption and emissions. There are few studies on the vehicle control based on the information of vehicle intelligent network and combine the information of engine and post processing system. In this paper, the information of the vehicle in front, traffic lights and the post processing system are provided to the controlled vehicle, so that the vehicle can follow the front car safely and achieve the optimal performance speed through the traffic lights, avoid the rapid acceleration, start up and other fuel consumption or emissions deterioration conditions, and create the optimal conditions for the post processing system.

Research of Post Injection Strategy of an EGR Diesel Engine to Improve Combustion and Particulate Emissions Performance: Application on the Transient Operation

Mobile source emissions have already accounted for a large proportion of environmental pollution, which seriously affect the symmetric characteristics of atmosphere, and automobile emissions have extremely serious deterioration of emissions under transient operation, especially particulate emissions. These factors exacerbate the asymmetry of the environment. So, the paper reports an experiment about the improvement of post injection strategy on combustion, regulated emissions (HC, CO, and NOx), and particle number emissions especially the emissions of different size particles in the transient process of an EGR diesel engine, meanwhile, the effects of post injection on the combustion of mixture are further analyzed by numerical simulation method. The test speed was 1600 r/min, and the torque increased from 5% of the maximum torque to 100%. The results indicated that the shorter the instantaneous loading time, the more severe the deterioration of particulate emissions, HC and CO emissions, but loading time has little effect on NOx emissions. The particles with the size range of 50–100 nm, 23–50 nm, and >100 nm are greatly affected by the loading process and post injection. In comparison, it has little effect on ultrafine particles with particle size of 15–23 nm and <15 nm. With the amount of post injection increased, the in-cylinder disturbance increased, and the oxygen-rich area in cylinder increased, the particle number concentration first decreased and then slightly increased. When the amount of post injection fuel is 2 mg and the main-post injection interval is 2000 us, the effects of suppressing particulate emissions are the best, for the 50–100 nm and >100 nm particles, the peak number concentration can be reduced by 25% and 50%, respectively. Due to the turbo charging lag, the peak of NOx emissions during the unloading process were slightly larger than the loading process.

Impact of Exhaust Gas Recirculation on Gaseous Emissions of Turbocharged Spark-Ignition Engines

Exhaust gas recirculation is one of the technologies that can be used to improve the efficiency of spark-ignition engines. However, apart from fuel consumption reduction, this technology has a significant impact on exhaust gaseous emissions, inducing a significant reduction in nitrogen oxides and an increase in unburned hydrocarbons and carbon monoxide, which can affect operation of the aftertreatment system. In order to evaluate these effects, data extracted from design of experiments done on a multi-cylinder 1.3 L turbocharged spark-ignition engine with variable valve timing and low-pressure exhaust gas recirculation (EGR) are used. The test campaign covers the area of interest for the engine to be used in new-generation hybrid electric platforms. In general, external EGR provides an approximately linear decrease of nitrogen oxides and deterioration of unburned hydrocarbon emissions due to thermal and flame quenching effects. At low load, the impact on emissions is directly linked to actuation of the variable valve timing system due to the interaction of EGR with internal residuals. For the same external EGR rate, running with high valve overlap increases the amount of internal residuals trapped inside the cylinder, slowing down combustion and increasing Unburnt hydrocarbon (HC) emissions. However, low valve overlap (i.e., low internal residuals) operation implies a decrease in oxygen concentration in the exhaust line for the same air–fuel ratio inside the cylinders. At high load, interaction with the variable valve timing system is reduced, and general trends of HC increase and of oxygen and carbon monoxide decrease appear as EGR is introduced. Finally, a simple stoichiometric model evaluates the potential performance of a catalyst targeted for EGR operation. The results highlight that the decrease of nitrogen oxides and oxygen availability together with the increase of unburned hydrocarbons results in a huge reduction of the margin in oxygen availability to achieve a complete oxidation from a theoretical perspective. This implies the need to rely on the oxygen storage capability of the catalyst or the possibility to control at slightly lean conditions, taking advantage of the nitrogen oxide reduction at engine-out with EGR.

Bright silicon vacancy centers in diamond/SiC composite films synthesized by a MPCVD method

SiC is always produced forming diamond/SiC composite films owing to the oversaturated doping of Si atoms during the preparation of high emission SiV centers. As a higher refractive index material (n = 2.72), the presence of SiC could possibly lead to inefficient photo-luminescent (PL) collection of SiV centers with total internal reflection. In order to understand such effect, different diamond/SiC films were deposited in a 915 MHz microwave plasma CVD (MPCVD) using the reactive gas of tetramethylsilane (TMS). The microstructure and photoluminescence of SiV centers were systematically investigated. It is found that the addition of TMS gas leads to the formation of cubic β-SiC and the refinement of diamond crystals. At the TMS gas flow of 5 sccm, the concentration of β-SiC is about 10% and the average diamond size is about 98 nm. The film exhibits the optimized PL emission of SiV centers, with the ratio of SiV PL to diamond Raman peak being 21.4. Increasing TMS gas flow leads to the increase of the concentration of β-SiC and the deterioration of PL emission of SiV centers. These results reveal that the introduction of TMS gas at a low flow advances the formation of diamond/SiC film containing high-brightness SiV centers.

Clinical Profiles of DFNA11 at Diverse Stages of Development and Aging in a Large Family Identified by Linkage Analysis.

The phenotype of DFNA11 consists of specific features at diverse developmental and age stages. Only eight mutations have been identified for autosomal dominant non-syndromic hearing loss related to MYO7A (DFNA11), and the onset and progression of DFNA11 are poorly understood. After linkage analysis and following Sanger sequencing in a family suspected to have autosomal dominant hereditary hearing loss, we analyzed the audiometric and vestibular functions and their long-term changes in the subjects carrying the variant. A reported variant of uncertain significance, NP_000251.3:p.Arg853His, in MYO7A was detected and cosegregation data of this large family provided evidence that the variant was likely pathogenic for DFNA11. Family members with the variant had no other symptoms associated with hearing loss and were confirmed to have autosomal dominant non-syndromic sensorineural hearing loss. Audiograms tended to show gently sloping configuration in childhood and flat configuration after the age of 30 years. Hearing loss at high frequencies progressed slowly, while hearing at low frequencies started to deteriorate later but progressed more rapidly. Some subjects showed partly abnormal results in the distortion products of otoacoustic emissions before the elevation of hearing thresholds. Vestibular function was within the normal range in all the subjects tested. We revealed that hearing loss at high frequencies was mainly noted in early developmental stages and that thresholds increased more rapidly in the low frequency range, resulting in changes in audiometric configuration. Deterioration of distortion product otoacoustic emissions (DPOAE) before the elevation of hearing thresholds was considered as a clinical feature of DFNA11.

Characteristics of the Spatio-Temporal Trends and Driving Factors of Industrial Development and Industrial SO2 Emissions Based on Niche Theory: Taking Henan Province as an Example

Industrial development is critical in improving a nation’s economy and in how it consumes energy resources. However, such development often causes environmental problems. Among others, the haze caused by industrial SO2 emissions is particularly prominent. Based on Niche theory and combined with Exploratory Spatial Data Analysis (ESDA, a decoupling index model, and a Logarithmic Mean Divisia Index (LMDI) factor decomposition model, this paper reports a study on the spatio-temporal distribution and the driving factors of industrial development and industrial SO2 emissions of cities in Henan, China between 2005 and 2014. The results showed that over the studied period in Henan: (1) SO2 emissions reduced by 4.56 × 105 tons and showed a slowly decreasing trend, which gradually transitioned to a “green health” industrial structure in Henan cities; (2) studied cities with high and low industrial niche values (0.038–0.139) showed an absolute decoupling relationship between industrial development and industrial SO2 emissions; (3) except for Zhengzhou city and Hebi city, other studied cities showed a trend of gradually increasing industrial output; (4) along with increases in the values of industrial output, studied cities showed increased levels of SO2 emissions but with energy intensity and energy structure showing a fluctuating trend of increases and decreases in their contributions to SO2 emissions; and (5) the energy consumption intensity and environmental technology were critical factors that were conducive to industrial SO2 emissions and the evolving industrial structure. These findings are important for the control of industrial SO2 emissions, though the levels of their influences are different in different cities. The scale of industrial production and the composition of energy structure in a region could lead to further deterioration of industrial SO2 emissions in the future.

Simulation of engine faults and their impact on emissions and vehicle performance for a liquefied petroleum gas taxi.

The deterioration of emissions control systems in a spark ignition engine is predominantly a gradual process of wear and tear occurring as vehicles accumulate mileage. As new innovations in engine and emissions technology have been progressively introduced to meet lower emissions targets, the impact of gradual deterioration of hardware has become more challenging to identify and quantify in the repair industry. When a pioneering emissions control programme utilising remote sensing to detect high emitting gasoline and liquefied petroleum gas (LPG) vehicles was to be introduced in Hong Kong, it became apparent the repair industry needed specialised training to assist with identifying the types of failures which would lead to high vehicle emissions. To identify the impact of hardware deterioration and failures, a Toyota Crown Comfort LPG taxi was used to demonstrate simulated failures of engine hardware systems to measure their impact on emissions, fuel consumption and drivability using a chassis dynamometer. This novel study simulated a broad range of deterioration and failures covering the intake, fuel supply, ignition, and exhaust systems. The results of the study showed significant THC and CO increases of up to 317% (0.604g/km) and 782% (5.351g/km) respectively for a simulated oxygen sensor high voltage fault and a sticky mixture control valve. The largest increase in NOx emissions was for restricted main fuel supply in the LPG vapouriser, producing an increase of 282% (1.41g/km). Fuel consumption varied with increases of up to 15.5%. Drivability was impacted with poor idle from a number of faults and especially by a worn throttlebody which produced rough acceleration characteristics as well. This study clearly highlights the importance of having properly maintained emissions and engine hardware systems to achieve optimal fuel economy and compliant emissions levels, which could be reproduced in other regions for prescribed emissions regulation.

Investigation of water injection benefits on downsized boosted direct injection spark ignition engine

Engine downsizing and boosting are key technologies to achieve the increasingly stringent emissions standards for spark ignition (SI) engines. However, knock is a major obstacle inhibiting further downsizing of SI engines. Water injection is a promising technology that has regained attention recently to solve the knock problem. In this paper, a 1.5L turbocharged gasoline direct injection (GDI) engine was modified by installing a water port injection (WPI) system on the intake manifold. The WPI system was modified from a GDI system and deionized water was pressured to 50 bar in a water tank by compressed nitrogen. The effect of WPI on engine combustion and emissions performance were experimentally investigated under different water/gasoline volume percentages and WPI timings. The results show that WPI has great potential in suppressing engine knock. At original engine setting (without adjustment of spark timing), all the combustion indexes related to knock are decreased by WPI, including maximum in-cylinder pressure (Pmax) and maximum pressure rise rate (Rmax). The flame kernel formation process (CA0-5), initiation combustion duration (CA0-10), early combustion duration (CA0-50) and major combustion duration (CA0-90) are deteriorated, resulting in decreased indicated mean effective pressure (IMEP) and thermal efficiency. By properly advancing spark timing, the combustion process can be improved, allowing the engine to achieve higher Pmax and better combustion phases without occurrence of knock. It is also found that the water/gasoline volume percentage should be kept within a proper range (30% in this study) because over WPI can lead to deterioration of combustion and pollutant emissions. WPI can effectively reduce the production of NO and CO emissions, while HC emissions are increased with the rise of water/gasoline volume percentage.

Lubrication, emissions, and performance analyses of LPG and petrol in a motorbike engine: a comparative study

ABSTRACTThe increased level of air pollution has caused the automobile industry to investigate alternate greener fuels to make vehicles more environmentally friendly. This study focuses on the performance, emission, and lubrication oil deterioration of 125cc motorbike engines, operated using petrol and LPG. Performance tests were conducted for a constant load using a water brake absorber using both fuels with fresh ((L.O.)F) and deteriorated lubrication oil ((L.O.)Det). Lubrication oil was deteriorated by running motorbike for both fuels. Emission testing was performed by applying three different loads and five different representative speeds. Moreover, NOx, HC, CO, and CO2 emissions levels were obtained using exhaust gas analyzer. For both fuels with (L.O.)F and (L.O.)Det, emission data was fitted to Weibull distribution and ascertained for 95% confidence interval for means. Flash point, ash, water content, total acid number (TAN), kinematic viscosity, and viscosity index tests were performed for analyzing both (L.O.)F and (L.O.)Det. Brake power, torque, and maximum speed of LPG fueled motorbike lowered by 17.4%, 10%, and 6.9% as compared to petrol using (L.O.)F, and 21%, 10.6%, and 7.7% using (L.O.)Det respectively. The average specific NOx decreased by 11.5% for LPG. The lubrication oil TAN increased by 65.2% and 21.7% for petrol and LPG respectively.