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Cycle-to-cycle changes in diesel exhaust gas emissions were investigated under two transient operation patterns: One, “an interval step decreasing and increasing load”, where the fuel amount is rapidly decreased from high to low loads, and after an interval, Δtint the fuel amount is abruptly returned to the initial level. The other is “a ramp increasing load”, where the fuel amount is increased gradually. Except just after the step increase in fuel amounts, the THC emissions were almost completely determined by the piston wall temperature and fuel amount. However, the THC concentrations immediately after the step increase in fuel amounts were much higher than the value of the corresponding steady state operation with the same piston wall temperature. This overshoot concentration, ΔTHC, was almost constant at different intervals, Δtint and it can be suppressed by ramp increased loading.

An emissions programme has been undertaken to gain information on the effect of selected fuel parameters on gasoline direct injection (G-DI) vehicle technology(1) with respect to exhaust emissions. Seven fuel parameters, namely aromatic, methyl-tertiary-butyl ether (MTBE), sulphur and olefin content as well as 3 distillation parameters covering the whole boiling range, were independently investigated. It was found that, overall, the fuel effects on regulated (THC, CO, NOx), particulate (Pm), and CO2 emissions were relatively small.

The influence of the molecular structure of hydrocarbon fuels on soot, SOF, and NOx emissions from a diesel engine was analyzed while ignition delay and other physical fuel properties were kept constant. Mixtures of normal paraffin (n-tetradecane) and iso-paraffin (heptamethylnonane) were used as a base fuel and one of 5 kinds of hydrocarbons including mono-aromatic, di-aromatic, and non-aromatic was added. The aromatic content varied in the range of 0-60 vol % for the mono-aromatic fuels and 0-40 vol % for the di-aromatic fuels. The experimental results showed that regardless of the molecular structure of the fuel, both particulate and NOx emissions increased linearly with the C/H atomic ratio of the fuels under constant ignition lag. The increase in particulate emissions with C/H atomic ratio was caused by increases in dry soot. The SOF, THC, and BSEC were little affected by the C/H atomic ratio and molecular structure of the fuels.

Motorcycles account for almost 80% of private vehicles in Indonesia, with an annual growth rate of 12% per year. This paper aims to investigate the emission profiles of CO2, CO, HC and NOx based on typical fuel and motorcycle types in Indonesia. Questionnaire surveys were undertaken to gather fuel type, engine technology and capacity representing the motorcycle population in Bandung City, Indonesia. Emissions were measured based on six-speed variations on a chassis dynamometer. Questionnaire surveys from 290 respondent show that EURO II and EURO III technology with engine capacity less than 150cc is the most utilized type of motorcycle in Bandung. Most of the users’ chose RON 90 and RON 92 gasoline. Based on the results, four groups of 5 motorcycle of EUROII-RON90, EUROII-RON92, EUROIII-RON90, and EUROIII-RON92 were tested. Emission data showed that the higher the speed, the lower the emission, except for CO and NOx which have a different pattern.

Bioethanol is being used as an alternative fuel throughout the world based on considerations of reduction of CO2 emissions and sustainability. It is widely known that ethanol has an advantage of high anti-knock quality. In order to use the ethanol in ethanol-blended gasoline to control knocking, the research discussed in this paper sought to develop a fuel separation system that would separate ethanol-blended gasoline into a high-octane-number fuel (high-ethanol-concentration fuel) and a low-octane-number fuel (low-ethanol-concentration fuel) in the vehicle. The research developed a small fuel separation system, and employed a layout in which the system was fitted in the fuel tank based on considerations of reducing the effect on cabin space and maintaining safety in the event of a collision. The total volume of the components fitted in the fuel tank is 6.6 liters.

The Biodiesel is an alternative diesel fuel derived from vegetable oil or animal fat by chemical reaction termed transesterification. Comparing with diesel fuel, biodiesel has many advantage such as: It can supply new energy source; It is renewable fuel and can reduce net CO2 cycle; It helps reduce exhaust gas emission to meet the future legislation due to oxygen content and high cetane number; It decrease impact to the environment due to high biodegradable. Southeast Asia, located in tropical area, has potential source to produce biodiesel. In Indonesia, Physic Nut oil now is considered as one of the most advantage source to make biodiesel due to it is non-edible and in-commercially exploited. The using of biodiesel from Physic Nut oil on diesel engine can supply as a new energy source replaced for diesel fuel and substituted palm oil as biodiesel raw material during the periods of high food sector demand.

Diesel combustion and exhaust gas emissions under transient operation (when fuel amounts abruptly increased) were investigated under a wide range of operating conditions with a newly developed gas sampling system. The relation between gas emissions and piston wall temperatures was also investigated. The results indicated that after the start of acceleration NOx, THC and smoke showed transient behaviors before reaching the steady state condition. Of the three gases, THC was most affected by piston wall temperature; its concentration decreased as the wall temperature increased throughout the acceleration except immediately after the start of acceleration. The number of cycles, at which gas concentrations reach the steady-state value after the start of acceleration, were about 1.2 times the cycle constant of the piston wall temperature for THC, and 2.3 times for smoke.

Amidst the rising demand to reduce CO2 and other greenhouse gas emissions in recent years, gasoline homogeneous-charge compression ignition (HCCI) has gained attention as a technology that achieves both low NOx emissions and high thermal efficiency by means of lean combustion. However, gasoline HCCI has low robustness toward intracylinder temperature variations, therefore the problems of knocking and misfiring tend to occur during transient operation. The authors verified the transient operation control of HCCI by using a 4-stroke natural aspiration (NA) gasoline engine provided with direct injection (DI) and a variable valve timing and a lift electronic control system (VTEC) for intake air and exhaust optimized for HCCI combustion. This report describes stoichiometry spark ignition (SI) to which external exhaust gas recirculation (EGR) was introduced, HCCI ignition switch control, and changes in the load and number of engine revolutions in the HCCI region.