THE JOURNAL OF ENGINE RESEARCH
Year:2020 | Volume:- | Issue:57 |Papers Count:7

The main objective of this research is to study the effects of JP-4-biodiesel-diesel fuel blends and operating parameters on the emission characteristics of a CI engine. The experimental tests were performed on a four-cylinder DI diesel engine. The Mixture-RSM method was used to develop mathematical models based on experimental data. The results showed that with the increase of the biodiesel proportion in the fuel blend, the emission of hydrocarbon and carbon monoxide in the exhaust decreases due to oxygen contents in the molecular structure of biodiesel that leads to effective combustion. According to the results, HC and CO emissions boosted up significantly with the use of jet fuel JP-4 in fuel mixture due to the lower cetane index of jet fuel in comparison with diesel and biodiesel. Results also indicated that the NOx formation is highly related to biodiesel proportion in fuel mixture due to less compressibility and its higher cetane number. On the other hand, the results indicated that NOx emissions reduced by using JP-4 as a result of retarded combustion of jet fuel that reduces combustion temperature. According to the results, CO and HC emission decreased at higher engine loads due to a more complete combustion condition. However, the NOx emission continuously intensifies at the higher levels of engine load due to the arising temperature of combustion gas. Generally, the results indicated that the use of JP4 fuel can improve NOx emissions of the engine but it does not have a desirable effect on other emission characteristics of the engine.

This research proposes the combination of a dual-loop non-organic Rankine cycle (DNORC) with an internal combustion engine to increase the output power of the recovery system by focusing on the increase in the energy input and system efficiency. In doing so, it investigates the strategy of increasing the mean effective temperature of heat addition in the high-temperature Rankine cycle (HTRC) (to improve the system efficiency and the strategy of increasing the waste heat entering the low-temperature Rankine cycle (LTRC) (to increase the energy input. In this recovery system, by focusing on the recovery of the waste heat from the engine cooling system and exhaust, the radiator can be removed from the engine cooling system, and by mounting fewer parts on the engine, not only can extra power be generated but also the engine can be cooled down faster and more efficiently. By using a thermodynamic analysis, the appropriate matching conditions between the DNORC with the engine are determined. The results showed that as the input energy increased, the recovery rate and system efficiency also increased. The output power of the recovery system exceeded 20kW and the efficiency of the whole engine and the recovery system increased to 33%.

The work involved a fundamental study of auto-ignition under unusually high knock intensities for an optical spark ignition engine. The single-cylinder research engine adopted included full bore overhead optical access capable of withstanding continuous peak in-cylinder pressures of up to 150bar. A heavy knock was deliberately induced under relatively low loads using inlet air heating and a primary reference fuel blend of reduced octane rating. High-speed chemiluminescence natural light imaging was used together with simultaneous heat release analysis to evaluate the combustion events. Multiple centered auto-ignition events were regularly observed to lead into violent knocking events, with knock intensities above 140 bar observed. The ability to directly image the events associated with such a high magnitude of knock is believed to be a world-first in an optical engine. The multiple centered events were in good agreement with the developing detonation theory proposed elsewhere to be the key mechanism leading to heavy knock in modern downsized SI engines. The accompanying thermodynamic analysis indicated a lack of relation between knock intensity and the remaining unburned mass fraction burned at the onset of the auto-ignition. Spatial analysis of the full series of images captured demonstrated the random location of the initial auto-ignition sites, with new flame kernels forming at these sites and initially growing steadily and suppressing further growth of the main flame front before violent detonation at speeds well over the imaging frequency of the camera.

To meet consumer and legislation requirements, various technologies have been used worldwide to achieve optimal fuel consumption and to reduce greenhouse gas emissions. One of the proposed technologies is cylinder deactivation using various methods, including, injectors cutting off, closing the intake and exhaust valves and crankshaft decoupling. In this paper, a GT-Power model is created to investigate the engine performance of a 1. 7L bi-fuel natural-gas engine. The model is also evaluated to predict performance differences between cylinder deactivation and nominal four-cylinder operation, including torque, power, brake specific fuel consumption and exhaust gas temperature. The results showed that cylinder deactivation (CDA) capable of increasing exhaust gas temperature until 40° C, also brake specific fuel consumption (BSFC) reduced by 21%. Comparisons are made between periods of 1500 to 5500 rpm.

Nobody escapes the importance of the air/fuel mixture preparation in internal combustion engines, whatever is the thermodynamic cycle they work on and the adopted fuel. The short time between the fueling and the start of the combustion is crucial for the best mixture formation and its burning for energy optimization and the pollutant production. The always stringent vehicle emissions rules led engine research toward the use of high-pressures and direct-injection systems for allowing a best atomization/vaporization of the fuel while, as drawback, the downsizing of the combustion system results in increasing of fuel impact on the combustion chamber and cylinder line with HC and particulate matter increase at the exhaust. A complete description of the injected fuel, its spread in the chamber with primary and secondary breakups, the vaporization, the mixture with the air and the combustion are of basic importance to govern the process and help new design architectures. Optical characterization has shown it’ s powerful in describing these processes without interfering with their evolution both in stationary and reciprocating devices. Imaging and spectroscopic techniques allow us to follow the physic-chemical transformations of the initial bulk of fuel in the mixture, production of primary and secondary species and individuate the potential sites of pollutant production. Furthermore, the results constitute a data set for initializing and calibrating numerical codes for provisional, results and behavior of diverse injecting systems and at different ambient conditions, and last but not the least inside the engine. In this paper, a tracking shot of optical techniques adopted to depict the fuel spread in a quiescent optical accessible vessel at engine-like conditions is reported for practices of fuel direct injection in engines.

Under the crisis of global warming and drastic climate changing, carbon-neutral renewable energy is considerably proposed as a feasible clean alternative energy to fractionally replace fossilized fuel. To cop up with ever stringent emission regulations, researchers have investigated different types of renewable fuels like biodiesel and water emulsion. The fuel physical characteristics are among the most important parameter to determine the quality of each fuel before it being tested in the engine. This study aims to evaluate the stability period and mean droplet size of the particles and to characterize the physicochemical properties of emulsified biodiesel blend B20 in terms of kinematic viscosity, density and calorific value with different percentage of water; 5%, 10%, 20%, and 30%. The tested fuel samples were compared with diesel fuel and blended palm biodiesel (B20). The experimental results show that when the proportion of water was increased in diesel-biodiesel blends, the dispersed water droplets become larger. The stability period in terms of days for emulsion fuels becomes lower when the amount of water was increased to the blends. The least stability period for emulsion obtained by emulsion with 20% and 30% water content which is 2 days. The kinematic viscosity and density of biodiesel emulsions were larger than those of the neat biodiesel. The calorific value for emulsion with 5% water content is comparable to blended fuel and conventional diesel even though there was a slight reduction.

Recently, environmental concern and demand for a catalyst’ s high performance have increased and many research activities focused on the operation of a three-way catalyst (TWC) at the end of its lifetime. Catalyst aging is the loss of catalytic activity over time that has crucial importance in emission of three-way catalyst. The aim of this paper is, investigating experimentally the performance of a fresh and aged three-way catalytic converter (TWC) in legislative driving cycle. For this, vehicle emission test with fresh and aged catalyst was carried out. In this study a commercial catalyst was used, and was aged in a motor-rig, with SBC cycle (Standard Bench Cycle). The total conversions of HC, CO and NOx were decreased over the lean-rich cycles in transient conditions. In the real driving condition, almost in the all-time, the engine has transient condition and in this condition, the non-aged catalyst, achieves higher conversion for times with lambda variations.