This paper deals with the use of gasoline-methanol and gasoline-ethanol mixtures in a small four-stroke engine of internal combustion that is used for the movement of a small alternative generator. It was observed that CO and HC emissions decrease compared to gasoline when the percentage of methanol, ethanol in the fuel was increased, under different load conditions (without load conditions and under full electrical load conditions). The use of gasoline-methanol mixtures showed a higher decrease of emissions. When the mixtures of gasoline-70%methanol and gasoline-90%ethanol and 100%ethanol for which the engine malfunctioned, the rpm of the engine were not constant and the emissions were increased. It is also important that (with the existing regulation of the fuel/air ratio that refers to gasoline) the engine functioned for the case of gasoline-methanol mixtures up to a concentration of -70%methanol mixture, while for the case of gasoline-ethanol mixtures until the use of 100%ethanol. Furthermore, during the use of the mixtures of gasoline-methanol and gasoline-ethanol there was a small increase of fuel consumption when the percentage of the methanol or ethanol in the fuel was increased.
This paper presents and discusses experimental data obtained during driving tests simulating the test cycle, ECE 15, and relates exhaust gas levels of hydrocarbon (HC) and carbon monoxide (CO) to catalyst outlet±inlet temperature differences. It also presents the preliminary results from the operation of a microcontrolled on-board diagnostics (OBD) II catalyst efficiency assessment system based on a statistical analysis of the catalyst outlet±inlet temperature difference thermocouple signal. There are indications that this system performs satisfactorily after an adequate warm-up period, if a sampling period in the order of 300±400 s is allowed.Although this operating principle is supported by considerable experimental evidence, there are several technical problems that must be overcome before it can comply to the OBD II requirements. Firstly, as engine loads increase, the efficiency of all catalysts tested is improved considerably by the high exhaust gas temperatures. Furthermore, as the catalyst outlet±inlet temperature difference tends to decrease, so does the sensitivity of the measurements. During driving, catalyst outlet±inlet temperature differences could also be affected by other external factors such as the car speed, rain or snow etc., or long-term temperature sensor drift. Present results indicate that catalyst outlet±inlet temperature difference is also influenced by the ambient temperature. A preliminary analysis of the data indicates that a linear relationship may exist between these two quantities, however, more tests are required for a statistical proof of this assertion.In spite of these problems, the results presented here tend to support the idea that a catalyst performance assessment system using temperature probes is technically feasible. However, further tests are required under various engine operating conditions and environments before a final conclusion can be drawn.
This article addresses a construction prepared to allow the function of an outboard engine in conditions similar to the factual. An outboard gasoline engine with max power 4HP was placed on the referred construction. In order to measure the performance of the entire powertrain, a prototype measurement procedure was developed. According to this procedure the measurement of the force is made by a direct connection between the engine's rpm and applied load. During the measurements operating characteristics of the engine, as well as the exhaust gases, were recorded. For the measurement of the emitted pollutants, a laboratory protocol and measurement standards defined by 40 CFR 1045 were used.
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