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.
Two-stroke (2S) engines still play a key role in the global internal combustion engine (ICE) market when high power density, low production costs, and limited size and weight are required. However, they suffer from low efficiency and high levels of pollutant emissions, both linked to the short circuit of fuel and lubricating oil. Low- and high-pressure direct injection systems have proved to be effective in the reduction of fuel short circuiting, thus decreasing unburnt hydrocarbons and improving engine efficiency. However, the narrow time window available for fuel to be injected and homogenized with air, limited to few crank-angles, leads to insufficiently homogenized fuel-air mixtures and, as a consequence, to incomplete combustions. The use of prechambers can be a well-suited solution to avoid these issues.
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.
In recent years, the supercharged spark ignition engine (SI engine) is spread out in the field of passenger vehicle. However, it has a problem of abnormal combustion which is called Low Speed Pre-ignition (LSPI). It is cleared gradually that the character of lubricating oil effects on LSPI behavior. The lubricating oil which has a tolerance for LSPI has been introduced already in the market nowadays. However, cause and mechanism of LSPI occurrence does not clear sufficiently. In previous conference SETC 2018, it was reported that the peculiar behavior of LSPI corresponded with behavior of lubricating oil from piston crown. This paper focuses on frequency of lubricating oil scattering from piston crown.
Owing to the combined merits of Spark ignition (SI) and compression ignition (CI) engines, homogeneous charge compression ignition (HCCI) engine technology has been receiving a greater attention in the last three decades. HCCI is a promising concept for combustion engines to reduce both emissions and fuel consumption. Utilization of different alternative fuels for HCCI engines is yet to be explored more. In this investigation, an attempt was made to use acetylene as a fuel in an HCCI engine. For this purpose, a single cylinder, four stroke, air-cooled CI engine was converted into HCCI mode. Acetylene was inducted into the intake manifold by using manifold injection technique. Air at different densities was supplied to the HCCI engine. The effects of varying air density on the performance and emission characteristics of the HCCI engine were assessed and the results are presented in this paper
In industrial processes, combustion engines and co-generation plants, large amounts of waste heat are generated, which are often lost to the environment. The conversion of this thermal energy into mechanical work and ultimately into electrical power promises a significant improvement in energy utilization, the efficiency of the overall system and, consequently, cost-effectiveness. Therefore, the use of a Rankine Cycle is a well-established technical process. A recent research project investigates a novel expansion machine to be integrated into an RC-process to convert the heat energy into mechanical work. Primarily, the present work deals with the fluid dynamic simulation of this expander, which is based on the principle of a rotary piston engine. The aim is to develop, analyze and optimize the process and the corresponding components. Hence, a CFD model has to be built up, which should correspond as closely as possible to the requirements and geometries of the physical engine.
For improving the thermal efficiency and the reduction of hazardous gas emission from IC engines, it is crucial to model the heat transfer phenomenon starting from the intake system and predict the intake air’s mass and temperature as precise as possible. Previously the authors developed an empirical equation based on an experimental setup of an intake port model of an ICE in order to be implemented into the engine control unit and numerical simulation software for heat transfer calculations. The authors developed an empirical equation based on the conventional Colburn analogy with the addition of Graetz and Strouhal numbers. Introduced dimensionless numbers were used to characterize the entrance region, and intermittent flow effects, respectively.
The oxidation of raw materials, such as phenolic resin, in the pad during the braking depends on the temperature but also on the oxygen diffusion capability through the brake pad. Determination of oxygen diffusion is a key point in knowing how deep from the surface tribochemistry can take place. In previous work from RIMSA, it was observed that iron sulphide had been reacted below the surface of the brake pad, suggesting that tribochemistry does not only take place on the surface. The diffusion of oxygen through the pad is a drawback because it induces the matrix decomposition that contributes to intra-stop CoF instability and consequently worsens NVH. This study is focused on determining the oxygen diffusion through brake pads using oxidized iron sulphide particles as indicator parameter. Iron sulphide has a peculiar microstructure (rough microstructure) when it becomes oxide that can be recognized easily, making it a good marker.
Gray cast iron brake rotor experiences substantial wear during the braking and contributes largely to the wear debris emissions. Surface coating on the gray cast iron rotor represents a trending approach dealing with the problems. In this research, a new plasma electrolytic aluminating (PEA) process was used for preparing an alumina-based ceramic coating with metallurgical bonding to the gray cast iron. Three different types of brake pads (ceramic, semi-metallic and non asbestos organic (NAO)) were used for tribotests. Performances of PEA coatings vs. different brake pad materials were comparatively investigated with respect to their coefficients of friction (COFs) and wear. The PEA-coated brake rotor has a dimple-like surface which promotes the formation of a thin transferred film to protect the rotor from wear. The transferred film materials come from the wear debris of the pads. The secondary plateaus are regenerated on the brake pads through compacting wear debris of the pads.
A new type of electric brake booster, which can control brake pedal feeling completely with software, has been developed to explore how a brake system can be used to differentiate and personalize vehicles. In the future, vehicles may share an increasing amount of hardware and rely more heavily on software to differentiate between models. Car sharing, vehicle subscriptions, and other new business models may create a new emphasis on personalization of vehicles that may be achieved most cost effectively using software. This new brake booster controls brake pedal force and brake pressure independently based on the brake pedal stroke so that the pedal feeling is completely defined by software. The booster uses two electric motors and one master cylinder. One electric motor controls pedal force and provides an assist force that amplifies the force that the driver applies to the brake pedal.
In order to keep the coefficient of friction stable, some additives such as metal sulphides, are included in the brake pads formulation. Previous work from RIMSA has shown that oxidation temperature range of the metal sulphides can be one of the key properties to explain their contribution to the performance and wear of a PAD. This new work is a step forward in the interpretation of the mechanism of sulphides as chemically active additives in the brake pads. Phenolic resin is the matrix of the brake pads and starts to decompose around 300 ºC in presence of oxygen and temperature. In order to establish a connection on between sulphide oxidation and phenolic resin degradation, several studies based on heat treatment of blends of different metal sulphides (Iron sulphide, Tin sulphide and Composite sulphide) with phenolic resin have been done. Then the material evolution was studied with techniques such as TGA - DSC, XRD, IR and SEM - EDS.
A study was performed to compare the performance of automotive friction elements, each manufactured with one of two different coke fillers. Coke #1 is a conventional calcined petroleum coke, and coke #2 a proprietary, calcined coke manufactured from a non-petrochemical feedstock. Subject coke materials were fully characterized, physically and chemically. Both coke materials are similar in their respective physical properties, including morphology, hardness, and crush strength. However, there is a significant difference in the trace metal content of the two materials, with coke #1 containing a higher content of sulfur, calcium, iron, nickel, and vanadium than coke #2. Nickel and vanadium are considered potential environmental hazards. Initial friction element evaluation was performed using the J661 Brake Lining Quality Test Procedure (Chase Test). Ultimately each coke material was formulated into two different automotive brake elements.
Design and Simulation Analysis of Braking system for ATV is carried out with the assistance of Ansys and MATLAB. Heat generated increases the temperature of the disc brake at the rubbing surface resulting in thermal stresses in the components of the braking system. Static, Structural, Thermal, Dynamic, Computational Flow Dynamics, Vibrational & Fatigue Behaviour of Ventilated brake disc Rotor, Hub and Brake Caliper are analysed. Stainless Steel, SS-410 material configuration has been considered for disc brake rotor and results obtained are analysed in terms of performance, longevity and efficiency. Braking efficiency and stopping distance curve are analysed from their characteristics plot. Vibrational Behaviour, Static and Structural Behaviour, Thermal Behaviour, Performance Efficiency, Flow Behaviour of Ventilated Disc Brake Rotor can be easily depicted with respect to Bump and Droop during Acceleration, High Climb and manoeuvrability.
In the last decade, the increasing electrification of road transports has stimulated the look for new braking systems with a high corrosion resistance. This resulted in a fervent research activity behind the development of disc brakes with a reduced corrodibility under demanding tribocorrosive environments. Despite of this, a significant reduction of the cast iron disc corrodibility can be achieved not only by developing variously coated rotors, but also by modulating the intrinsic corrodibility of iron. This can be done by and ad-hoc refining of the cast iron: a) alloying elements concentration; b) microstructure; and c) carbon content and morphology. At this regard, in this contribution, the corrosion properties of a representative ensemble of cast iron specimens are reviewed.
Brake calipers for high-end cars are typically realized using Aluminum alloys, with Silicon being the most common alloying element. Despite the excellent castability and machinability of AlSix alloys, anodization is often necessary in order to provide to AlSix components the required corrosion resistance or when the braking system has to withstand to severe chloride-rich environments . Even if the anodization process is known for almost 100 years, a continuous research and process optimization can lead to the development of anodic layers with enhanced morphological and electrochemical properties, which enable a prolonged resistance of calipers under endurance corrosive tests (e.g. >1000hours Neutral Spray Tests).