Achieving stable combustion without misfire and knocking is challenging in premixed charge compression ignition (PCCI) especially in small bore, air cooled diesel engines owing to lower power output and inefficient cooling system. In the present study, a single cylinder, air cooled diesel engine used for agricultural water pumping applications is modified to run in PCCI by replacing an existing mechanical fuel injection system with a flexible common rail direct injection system. An advanced start of fuel injection (SOI) and exhaust gas recirculation (EGR) are required to achieve PCCI in the test engine. Parametric investigations on SOI, EGR and fuel injection pressure are carried out to identify optimum parameters for achieving maximum brake thermal efficiency. An SOI sweep of 12 to 50 deg. CA bTDC is done and for each SOI, EGR is varied from 0 to 50% to identify maximum efficiency points. It was found that EGR helps in extending the load range from 20 to 40% of rated load.
The fuel economy of recent small size DI diesel engines has become more and more efficient. However, heat loss is still one of the major factors contributing to a substantial amount of energy loss in engines. In order to a full understanding of the heat loss mechanism from combustion gas to cylinder wall, the effect of hole size and rail pressure under similar injection rate conditions on transient heat flux to the wall were investigated. Using a constant volume vessel with a fixed impingement wall, the study measured the surface heat flux of the wall at the locations of spray flame impingement using three thin-film thermocouple heat-flux sensors. The results showed that the characteristic of local heat flux and soot distribution was almost similar by controlling similar injection rate except for the small nozzle hole size with increasing injection pressure.
In the present work, a relative comparison of addition of water to diesel through emulsion and fumigation methods is explored for reducing oxides of nitrogen (NOx) and smoke emissions in a production small bore diesel engine. The water to diesel ratio was kept the same in both the methods at a lower concentration of 3% by mass to avoid any adverse effects on the engine system components. The experiments were conducted at a rated engine speed of 1500 rpm under varying load conditions. A stable water-diesel emulsion was prepared using a combination of equal proportions (1:1 by volume) of Span 80 and Tween 80. The mixture of Span 80 in diesel and Tween 80 in water was homogenized using an IKA Ultra Turrax homogenizer with tip stator diameter 18mm at 5000 rpm for 2 minutes. The water-in-diesel emulsions thus formulated were kinetically stable and appeared translucent. No phase separation was observed on storage for approximately 105 days.
Measuring brake emission is still a challenging non-standardized task. Extensive research is ongoing. Updates of work in progress are presented at SAE Brake Colloquium and PMP meetings. However, open items include how to achieve lower background concentration and how to design the brake enclosure. A low background concentration is essential as brake events are short and some emit in the range of reported background levels. Hence these emissions are difficult to distinguished from the background level. Even more critical, a high background concentration can result in a wrong particle number emissions value, either overestimated, background counted as emissions, or underestimated, background level subtracted, and low emission events no longer detected and counted. However, reducing the background level to less than 100 #/cm³ appeared to be quite challenging.
Raising demands towards lightweight design paired with a loss of originally predominant engine noise pose significant challenges for NVH engineers in the automotive industry. From an aeroacoustic point of view, low frequency buffeting ranks among the most frequently encountered issues. The phenomenon typically arises due to structural transmission of aerodynamic wall pressure fluctuations and/or, as indicated in this work, through rear vent excitation. A possible workflow to simulate structure-excited buffeting contains a strongly coupled vibro-acoustic model for structure and interior cavity excited by a spatial pressure distribution obtained from a CFD simulation. In the case of rear vent buffeting no validated workflow has been published yet. While approaches have been made to simulate the problem for a real-car geometry such attempts suffer from tremendous computation costs, meshing effort and lack of flexibility.
This work focuses on the effects of cooled Low Pressure EGR and Water Injection observed by conducting experimental tests consisting mainly of Spark Advance sweeps at different cooled LP-EGR and WI rates. The implications on combustion and main engine performance indexes are then analysed and modelled with a control-oriented approach, showing that combustion duration and phase and exhaust gas temperature are the main affected parameters. Results show that cooled LP-EGR and WI have similar effects, being the associated combustion speed decrease the main cause of exhaust gas temperature reduction. Experimental data is used to identify control-oriented polynomial models able to capture the effects of LP-EGR and WI on both these aspects. The limitations of LP-EGR are also explored, identifying maximum compressor volumetric flow and combustion stability as the main ones.
Transportation system is at the brink of revolution and many new ways of mobility are arising in the market to ease the pressure on the established transportation infrastructure. Many companies and governments around the world are exploring innovative options in the space of shared mobility to reduce the overall carbon footprint. To expedite the adoption of shared mobility in India, it is necessary to make such options comfortable and cost-effective. One of the most effective way to make shared mobility options cost effective is to comfortably increase occupancy per vehicle footprint. This paper aims to evaluate a novel method of occupant seating to identify the maximum number of passengers a vehicle can accommodate without significant impact on occupant comfort. It is assumed that shared mobility options are used for a short duration of commute, and hence the comfort of the seat can be marginally compromised to increase the total number of occupants.
The pattern of utilizing the water/diesel emulsion fuels in engines had been given great importance due to its ecological and exhaustion of petroleum reserves. This investigation displays the impact of 1,4-dioxane emulsified fuel on performance and emissions at various operating pressures. 1,4-dioxane emulsified fuel (DWSD10) was prepared with 10% 1,4-dioxane, 10% water, 0.2% surfactant and 79.8% diesel. To estimate the engine performance and emissions, the engine was operated with 180 bar, 200 bar and 220 bar operating pressures and the output was equated with diesel fuel operating on normal pressure of 200 bar. BTE of 1,4-dioxane emulsified fuel at 220 bar was higher when compare with diesel fuel. CO, HC and BSEC were lower at 220 bar on par with diesel fuel. However, NOx was increases for the higher operating pressure. Overall, except NOx, at higher injection pressure (@220 bar) the 1,4-dioxane emulsified fuel outperforms the diesel fuel in terms of emission and performance.
Automotive manufacturers are constantly working towards enhancing the driving experience of the customers. In this context, improving the static and dynamic gear shift quality plays a major role in ensuring a pleasant and comfortable driving experience. Moreover, the gear shift quality of any manual transmission is mainly defined by the design of the synchronizer system. The synchronizer sleeve strut detent groove profile plays a vital role in defining the performance of the synchronizer system by generating the minimum required pre-synchronization force. This force is important to move the outer synchronizer ring (blocker ring) to the required index position and to wipe-out the oil from the conical friction surfaces to build rapid high cone torque. Both these functional requirements are extremely critical to have a smooth and quick synchronization of the rotating parts under dynamic shift conditions.
To tackle the problem arising due to emissions and to reduce them, complex after-treatment system is used. For efficient working of the after-treatment system it must operate at enough high temperature even at low loads for better conversion efficiency. Also, there is different temperature requirements for different catalyst used in SCR (Selective catalyst reduction) system. For this, various on engine strategies are implemented on modern diesel engines such as multiple fuel injection, late fuel injection, high fuel injection pressure and exhaust gas recirculation. Thermal management of exhaust gasses is an operating condition which must be triggered when there is need of elevated temperatures for efficient functioning of the after-treatment system. Thermal management includes SCR thermal management and regeneration.
Sealing is one of the important components in the automotive and aerospace industry. The primary function of the lip seal is to protect contamination and retaining the lubricant. This investigation relates to a study of contact pressure existence on sealing structure between there mating region. Sealing for steering intermediate shaft should sustain sliding motion between shaft and seal as well as protection of lubricant from contamination and retention. Contact pressure analysis of Steering intermediate shaft with hyper elastic rubber seal is done at static condition using ABAQUS. Experiments were also conducted to check contact pressure between seal and shaft by using Fuji-pressure film sensor. The result from CAE analysis was compared with experimental data with 75% of the correlation with respect to CAE. This analysis of contact pressure helps to support on giving enough interference between seal and shaft which satisfies the need of sealing for an intermediate shaft.
According to the latest emission standards, NOx and PM emission from on road heavy duty diesel engines need to have a dramatic reduction. To limit these emissions, an aftertreatment system consist of Diesel Oxidation Catalyst, Diesel Particulate Filter, Selective Catalytic Reduction and Ammonia Slip Catalyst is installed downstream of the engine. The aim of this paper is to analyze performance of Diesel Oxidation Catalyst (DOC) for light off, HC oxidation and NO to NO2 oxidation. The focus is on the effectiveness of Diesel Oxidation Catalyst by varying the parameters such as space velocity, HC dosing, exhaust flow rate and inlet temperature of catalyst. Usage of diesel oxidation catalyst in aftertreatment system results into lowered HC, CO and NO emissions which is helpful in meeting BS-VI legislation limits.
EGR flow within individual cylinder as per requirement has a great importance which controls the performance and emissions of the diesel engine. The work presented here, elaborates the mixing process of EGR in the manifold with the fresh charge entering into intake manifold and then into cylinder. The study is carried on our three-cylinder diesel engine. For the simulation of such highly pulsating flow, the boundary conditions were generated from 1D model & in the back end the 3D CFD is used to solve the EGR mixing in a transient phase. The mixing at each cylinder port is evaluated using the Air and CO2 mass fraction at outlet of each intake port. Being a transient nature of valve operation, the EGR distribution within the manifold observed stabilized in 9 cycles. It was observed that the flow pulsations at the EGR inlet have large influence on the EGR distribution.
Vehicles are one of the main sources of pollution in India, which produce substantial amount of pollutants. Gaseous pollutants are reason for major health problems; hence emission legislations are becoming increasingly stringent all over the world. India is also following the global trend of migrating in the Off-highway segment from Trem IIIA to Stage V legislation by 2024. This legislation change is calling for technological upgrade of all existing engines. EGR has been successfully proved as a useful technology to reduce NOx by decreasing the oxygen concentration and the peak temperature of the combustion. Due to compact design and space restriction, the distance required for the homogeneous mixing of fresh air and EGR is not enough. Therefore, the mixing of the EGR and distribution of the EGR over the cylinders may not be equal.
The current research over the use of nano additive as a distinguishable thing on decelerating hazardous diesel engine emissions. The experiment was conducted with biofuel, there is no significance of engine modifications for using the biofuel. The surplus amount of oxygen integrated within the biofuel can able to generate higher combustion rate relatively it produces more NOx, the NOx burden can be reduced with the help of REGR (reformed exhaust gas recirculation). The reforming of exhaust gases causes the measurable generation of smoke, CO and HC. In order to reduce the formation of above emissions, the affordable and sustainable alternate identified from the present research, by citronella biofuel with 100ppm Cobalt Chromite nano additive. The scrutinized output enumerates that the substantial reduction in HC, CO, and BSFC with elevated EGT (exhaust gas temperature) achieved by CBN-REGR than the typical usage of the traditional CB-EGR system.
Diesel-powered engines are used worldwide for efficient transportation and stationary power generation. The significant drawback of a diesel engine is its harmful emissions. The stringent emission norms enforced by the different organization demands effective catalyst system to control the gaseous emissions. Diesel oxidation catalysts are the extensively used technique for diesel engines to control HC and CO emissions. Currently the catalyst in the diesel oxidation system employs precious metals such as Pt/Pd/Rh to reduce the emissions and makes the DOC system expensive. This paper presents a cost-effective catalyst prepared to employ non-noble mixed oxides of copper and nickel supported on non-conventional support (i.e.) ceria doped calcium borophosphates (Ce-SCaPB). Initially, ceramic beads (5mm X 5mm) were coated with (Ce-SCaPB) support material. Secondly, the copper and nickel salts were deposited on the Ce-SCaPB coated ceramic beads and subsequently reduced and calcined.
The SAE formula student car organization constrained a rule to place a restrictor of diameter 20mm in between the throttle body and the engine inlet. The restrictor is a component that reduces and regulates the mass flow of air into the engine inlet. For this, a venture nozzle will be used as a restrictor in a vehicle to decrease the air pressure and increase the velocity in the intake manifold. Our proposed work aims to minimize the pressure drop by changing the convergent and divergent angles in the restrictor. For this by using solidworks eight various combinations of models with convergent angle as 13, 15 degrees, and divergent angle as 5,7 degrees was designed and analyzed using CFD fluent in ansys work bench. In this, 13 degree as convergent and 5 degree as a divergent model was found to have laminar airflow throughout with optimum pressure drop. The plenum is a large duct that equalizes the pressure drop caused by the restrictor in order to improve the efficiency of the engine.
The Indian automotive industry has migrated from BS IV (Bharat stage IV) to BS VI (Bharat Stage VI) emission norms from 1st April 2020. This two-step migration of the emission regulations from BS IV to BS VI demands significant engineering efforts to design and integrate highly complex exhaust after-treatment system (EATS). In the present work, the methodology used to evaluate the EATS of a high power-density 1.5-liter diesel engine is discussed in detail. The EATS assembly of the engine consists of a diesel oxidation catalyst (DOC), a diesel particulate filter with selective catalytic reduction coating (sDPF), urea dosing module and urea mixer. Typically, all these components that are needed for emission control are integrated into a single canning of shell thickness ~1.5mm. Moreover, the complete EATS is directly mounted onto the engine with suitable mounting brackets on the cylinder block and cylinder head.