José Ricardo Sodré

Fluid flow pressure drop through an annular bed of spheres with wall effects

A model has been developed to predict the pressure drop for flow through an annular packed bed of spheres at random distribution. Erguns equation, with a corrected flow velocity, is used. To consider the wall effect in the flow distribution, the annular section was divided into three regions: the external and internal wall regions, and an intermediate one, called transition. To find an average flow velocity, to be used in Erguns equation, a different treatment has been applied to the wall regions, with respect to the transition region. That was necessary due to the presence of a further wetted area and the distortion on the porosity distribution. Model prediction showed good agreement with experimental data. Experiments were carried out for fully developed turbulent flow of air, at steady state condition, through an annular bed with a radius ratio of 1.369 and a bed to particle diameter ratio of 8.258.

Exhaust emissions from a diesel power generator fuelled by waste cooking oil biodiesel.

The exhaust emissions from a diesel power generator operating with waste cooking oil biodiesel blends have been studied. Fuel blends with 25%, 50% and 75% of biodiesel concentration in diesel oil were tested, varying engine load from 0 to 25 kW. The original engine settings for diesel oil operation were kept the same during the experiments with the biodiesel blends. The main physical-chemical characteristics of the fuel blends used were measured to help with the analysis of the emission results. The results show that the addition of biodiesel to the fuel increases oxides of nitrogen (NO(X)), carbon monoxide (CO) and hydrocarbon (HC) emissions. Carbon dioxide (CO(2)) and exhaust gas opacity were also increased with the use of biodiesel. Major increase of NO(X) was observed at low loads, while CO and HC were mainly increased at high loads. Using 50% of biodiesel in diesel oil, the average increase of CO(2), CO, HC and NO(X) throughout the load range investigated was 8.5%, 20.1%, 23.5% and 4.8%, respectively.

Friction Factor Determination for Flow Through Finite Wire-Mesh Woven-Screen Matrices

Experiments were carried out to determine the pressure drop through an annular conduit filled with a plain square wire-mesh woven-screen matrix. The tests involved turbulent fully developed flow of air at steady-state conditions, with the modified Reynolds number (M(1−e )/Re), based on the hydraulic radius of the packed bed, ranging from 5 × 10−4 to 5 × 10−3 . The test section was built according to the geometry of a Stirling engine, simulating an annular regenerator with a radius ratio of 1.369 and a screen of mesh size 10. A corrected Ergun equation was used to correlate the experimental data, considering the wall effects. Comparisons with results obtained by other authors extended the validation of the correlation obtained to a wider range of modified Reynolds numbers (1 × 10−4 ≤ M(1 − e )/Re ≤ 1) and to different screen mesh sizes. The correlation has been found to work for annular and circular cross-section beds.

Comparison of engine power correction factors for varying atmospheric conditions

This work evaluates proposed methods to correct engine power output as a function of atmospheric conditions. The analysis was made through experiments carried out in a vehicle on the road, under different temperature, pressure and air humidity conditions. The vehicle had a four-cylinder gasoline-fuelled engine, with multi-point fuel injection system, variable intake pipe length and variable intake valve camshaft position. The vehicle was tested at sea level and at 827 m above sea level, corresponding to atmospheric pressures between 1027 and 926 mbar. Air temperature varied from 22,8 to 33,8 °C at the test locations. The measured performance parameter in the tests was the vehicle acceleration time. The acceleration times from 0 to 400 m, 0 to 1000 m, 40 to 100 km/h and 80 to 120 km/h were all recorded, leaving from an initial vehicle speed of 40 km/h. The engine power curve obtained in laboratory under a standard ambient condition was corrected to the conditions of the road tests by the correction factors proposed by the methods under evaluation, and the corresponding acceleration times were calculated and compared with the measurements from the road tests. The evaluated methods for power correction were the following: DIN 70020, SAE J 1349, JIS D 1001 and ISO 1585. The SAE J 1349 method provided the best approach between the experimental and calculated acceleration times.

Effects of atmospheric temperature and pressure on the performance of a vehicle

Abstract This paper describes the influence of the atmospheric conditions on the performance of a vehicle. Tests were carried out on the road, under different conditions of ambient temperature, pressure and humidity, measuring the acceleration time. The tested vehicle featured a gasoline-fuelled four-cylinder engine, with variable intake manifold length and multipoint fuel injection. The vehicle was tested at sea level and at an altitude of 827 m above sea level, with the ambient temperature ranging from 20 to 30°C. The times required for the vehicle to go from 80 to 120 km/h, from 40 to 100 km/h and to reach distances of 400 and 1000 m leaving from an initial speed of 40 km/h at full acceleration were recorded. The results showed the vehicle performance to be more affected by changes in the atmospheric pressure than in the temperature. An average difference of 3 per cent in the time to reach 1000 m, leaving from the speed of 40 km/h at full acceleration, was found between the atmospheric pressures tested, for a fixed temperature.

Potential vegetable sources for biodiesel production: cashew, coconut and cotton

This work presents a study on crude oil and biodiesel obtained from the seeds of the tropical plants Anacardium occidentale L (cashew), Cocos nucifera (coconut palm) and Gossypium hirsutum (upland cotton). The following crude oil and biodiesel physical–chemical properties were determined: acid number, iodine value, copper corrosivity, density and viscosity at different temperatures. Also, the chemical composition of the fatty acid methyl esters was measured using gas chromatography and a comparison was made with biodiesel from other sources reported in the literature. The analysis pointed out that cashew, coconut palm and upland cotton are potential sources for biodiesel production. Among the biodiesel types tested, cashew showed the highest oxidation stability.

INFLUENCE OF ENGINE OPERATING PARAMETERS ON ALDEHYDE EMISSIONS FROM AN ETHANOL-FUELED VEHICLE

Abstract This work presents results and analysis of experiments on aldehyde and the regulated pollutants CO, HC, and NOA emissions, with varying engine-running parameters. An ethanol-fueled vehicle was tested in a chassis dynamometer, following a standard urban cycle test procedure. The test simulated a medium-distance trip in an urban area, of approximately 5.8 km, with a warmed-up engine. The running parameters tested in the experiments were mixture equivalence ratio, the additional air flow used in decelerations (dash pot), the fuel interruption function in decelerations (cutoff), and gear-change speed. The results pointed to a reduction on aldehyde emissions for lower gear-change speeds and for richer fuel mixtures.

Cold start and drivability characteristics of an ethanol-methyl-t-butyl ether blend fuelled vehicle

Abstract An ethanol-methyl-t-butyl ether (MTBE) fuel blend was used as a substitute for hydrated ethanol to improve the vehicle cold start and drivability characteristics during the warm-up period. The vehicle was tested in a cold box, reaching a lower ambient temperature limit of -6deg;C, which represents the most severe weather condition experienced in Brazil. Different concentrations of MTBE in ethanol were investigated. The results show satisfactory drivability characteristics for the tested conditions, comparable with those found in gasoline-fuelled vehicles, thus overcoming the existing cold start difficulties in production ethanol-fuelled vehicles.

Influence of Friction Modifier Additives on the Tribology of Lubricating Oils

Current ambient and technological demands on automotive emissions and oil consumption motivate the development of basic lubricant oils of high thermal and chemical stability and use of highly specified additives. This work evaluates some types of friction modifier additives present in spark ignition and compression ignition engine oils, using a four-balls measuring device. The tribology of conventional lubricating oils were evaluated and compared to those of lubricating oils with friction modifier agents. The test results allowed for determination of the effects of utilization of friction modifiers in automotive lubricating oils.

Chromatograph determination of total and speciated hydrocarbons in the exhaust of a spark ignition engine

Abstract Gas chromatography tests have been applied to the exhaust gases of a spark ignition engine to determine the concentration of unburned fuel among the total hydrocarbons. The contribution of unburned fuel was determined with variation in several engine parameters. The fuel tested was isooctane. The varied parameters were the air-fuel ratio, engine speed, ignition timing, compression ratio and coolant and lubricant temperature. The results have shown that the unburned fuel is responsible for most of the HC emitted, 50-73 per cent, depending on the engine working conditions. Methane, acetylene, ethylene, ethane, propylene and isobutylene were also analysed, as well as isooctane. The total contribution of the lighter species remained practically unaltered when the parameters were varied, though their individual concentrations did change. Thus, the unburned HC was seen to determine all trends of exhaust hydrocarbons.