Vapor Pressure Of Gasoline Research Articles

Effect of diesel/gasoline/HCB blends and temperature on string cavitating flow in common-rail injector nozzle

Renewable clean fuel such as biodiesel, alcohol-based fuel blended with fossil fuel has been widely studied for applications in engines aiming at partial solution of fuel consumption and environment emission issues. These blending fuels have also shown advantages in new combustion modes like GCI and LTC. However, the fuel injector nozzle internal flow and spray behaviors of these blending fuels are still not well understood, which may largely influence the subsequent fuel–air mixture, combustion, and emission characteristics. The investigation of cavitation flow in the high-pressure common-rail injector nozzle and spray characteristics with blending fuels of gasoline, diesel, and hydrogenated catalytic biodiesel (HCB) was conducted in the present work. The real-size optical nozzle was used to visualize the nozzle internal cavitating flow and spray. It was found that, by adding gasoline into diesel and HCB, the string cavitation increased significantly, and the spray cone angle expanded, especially under low needle lift. This behavior can be interpreted as the lower viscosity and higher saturation vapor pressure of gasoline enhanced vortex and cavitation. It can be concluded that increasing fuel temperature significantly impacted the cavitation and affected the vortex lightly, suggesting that with higher temperatures, blended fuels show better performance. As the fraction of HCB of gasoline/HCB blends increased, the cavitation inside nozzles was restrained due to its high viscosity. String cavitation can be interrupted by the needle tip, and the spray cone angle fluctuated enormously under this situation, which may cause uneven mixing of fuels and air.

Evaluation of Gasoline Evaporative Emissions from Fuel-Cap Removal after a Real-World Driving Event

This study evaluated gasoline evaporative emissions from fuel-cap removal during the refueling process (or “puff loss”) for one gasoline vehicle in the Japanese market. Specifically, the puff loss emissions were measured after a real-world driving event in urban Tokyo, Japan for different seasons and gasoline types. The experimental results indicated higher puff loss emissions during summer than in winter and spring despite using low vapor pressure gasoline during summer. These higher puff loss emissions accounted maximally for more than 4 g of the emissions from the tested vehicle. The irregular emission trends could be attributed to the complex relationships between physical parameters such as fuel-tank filling, ambient temperature, ambient pressure, and gasoline vapor pressure. Furthermore, an estimation model was developed based on the theory of thermodynamics to determine puff loss emissions under arbitrary environmental conditions. The estimation model included no fitting parameter and was in good agreement with the measured puff loss emissions. Finally, a sensitivity analysis was conducted to elucidate the effects of three physical parameters, i.e., fuel tank-filling, ambient pressure, and gasoline type, on puff loss emissions. The results indicated that fuel tank-filling was the most important parameter affecting the quantity of puff loss emissions. Further, the proposed puff loss estimation model is likely to aid the evaluation of future volatile organic compound emission inventories.

Effect of Environmental Components On the characteristic of Al-Daura Gasoline

An evaluation was conducted by adding two chemical blends to gasoline produced form Al Dorra refinery to studyIctane number of octans and Reid gasoline vapor pressure with different volume compositions. The two mixtures are Di-isopropylether/olive oil (DO) and Di-isopropylether/isopropanol (DI). The gasoline had been mixed with volume percentages of 8, 10 and 15. It was discovered that by adding the two blends of Di-isopropyl Ether/Olive Oil and Di-isopropyl Ether/Isopropanol, the octane number of gasoline risen continuously and linearly. The DI-gasoline blends developed greater gasoline octane number. Compared to the plain gasoline, the two additions observed a substantial reduction in Reid vapor pressure and calorific levels. Reid vapor pressure is shown to rise in the two blends.

Recent Trend in Ozone Levels in the Metropolitan zone of Mexico City

Ozone concentration in the atmosphere of Mexico City is analyzed for the period 2000-2006, finding an average reduction of 24%, in spite of not meeting the norm of 110 ppb in more than 42% of the days in Pedregal. The maximum ozone levels in the last three years were 250 ppb well above the norm of 110 ppb. The number ofvehicles registered in the Federal District has increased in the period by an average of 35%. Notwithstanding the increase in vehicular fleet, improvement of air quality is ascribed to the replacement of old cars by more efficient and less contaminating new cars. To decrease even more the ozone concentration, it is suggested to decrease furtherthe Reid Vapor Pressure of gasoline to 7.0 psia to reduce the evaporation of light olefins.

Droplet dynamics of DI spray from sub-atmospheric to elevated ambient pressure

In this study, one of the five jets issued from a 5-hole Direct Injection (DI) injector was studied in detail using Phase Doppler Particle Analyzer (PDPA) and high speed imaging techniques. The tests were carried out in a constant volume vessel with absolute ambient pressures ranging from 0.05 to 0.5MPa and injection pressures ranging from 6.0 to 15.0MPa. Throughout the test conditions, the jet trajectory deviation of the target jet is observed due to the gas pressure imbalance between the inner and outer sides of the target jet. Both the results from spray morphology and the time-resolved droplet velocity have demonstrated the bifurcation of the target jet during the spray process at sub-atmospheric and atmospheric ambient pressures. It is attributed to the joint effects of the pressure imbalance between the two sides of the target jet and the velocity distribution change at the nozzle exit which relates to the vapor pressure of gasoline. The increase in injection pressure advances and enhances the deviation of the jet trajectory due to the larger jet speed. The deviation and/or bifurcation of the target jet also changed the size distribution.

Flashboiling-induced targeting changes in gasoline direct injection sprays

By definition, flashboiling is referred to as superheated injections. The sudden occurrence of boiling inside the fuel can change the spray structure dramatically. Up to 99% of all injection processes during the New European Driving Cycle and 95% during ‘Real Driving Emissions’ tests are, with respect to mid-range cars, in a state of thermodynamic non-equilibrium below the specific vapor pressure of gasoline. Considering this fact, the scientific question is not the appearance of flashboiling during the operation of stoichiometric homogeneous charge direct injection gasoline engines but the intensity of occurring spray processes and their influence on nominal spray designs. As a consequence of induced targeting changes, the positive influence of flashboiling on the droplet size distribution and the penetration depth can be counteracted. As main driving factors for targeting changes, jet-to-jet interactions can be identified. By applying appropriate nozzle design features, the potential of flashboiling can be exploited and the targeting changes of the nominal spray designs, considered negatively, are avoided mostly. This work focuses on flashboiling-induced targeting changes, the so-called phenomenon of “spray collapse”: its root cause, development and avoidance.

Tuning of PI–PD controller using extended non-minimal state space model predictive control for the stabilized gasoline vapor pressure in a stabilized tower

Nonlinearities, uncertainties and large time delay widely exist in the industrial processes, which pose great difficulty to traditional proportional-integral-derivative (PID) control. Proportional-integral–proportional-derivative (PI–PD) controller, which is a modified form of PID controller, can get a better performance than PID control. However, due to the fact that PI–PD controller has an extra parameter, the difficulty of parameter adjustment is a major problem. In this paper, a new PI–PD method optimized by the extended non-minimal state space model predictive control (ENMSSMPC) is proposed to get the optimal parameters of PI–PD controller for dealing with the process complexity. The proposed PI–PD controller combines the advantage of ENMSSMPC and the simple structure of the PID controller and is tested on the stabilized gasoline vapor pressure in a stabilized tower. Results show that it outperforms traditional controllers such as PID controller, PI–PD controller, traditional model predictive control based PID and PIPD controllers (TPFC-PID and TPFC-PIPD) and IMC based Robust PID controller (Robust IMC-PID).

Impact of Higher Alcohols Blended in Gasoline on Light-Duty Vehicle Exhaust Emissions

Certification gasoline was splash blended with alcohols to produce four blends: ethanol (16 vol%), n-butanol (17 vol%), i-butanol (21 vol%), and an i-butanol (12 vol%)/ethanol (7 vol%) mixture; these fuels were tested in a 2009 Honda Odyssey (a Tier 2 Bin 5 vehicle) over triplicate LA92 cycles. Emissions of oxides of nitrogen, carbon monoxide, non-methane organic gases (NMOG), unburned alcohols, carbonyls, and C1-C8 hydrocarbons (particularly 1,3-butadiene and benzene) were determined. Large, statistically significant fuel effects on regulated emissions were a 29% reduction in CO from E16 and a 60% increase in formaldehyde emissions from i-butanol, compared to certification gasoline. Ethanol produced the highest unburned alcohol emissions of 1.38 mg/mile ethanol, while butanols produced much lower unburned alcohol emissions (0.17 mg/mile n-butanol, and 0.30 mg/mile i-butanol); these reductions were offset by higher emissions of carbonyls. Formaldehyde, acetaldehyde, and butyraldehyde were the most significant carbonyls from the n-butanol blend, while formaldehyde, acetone, and 2-methylpropanal were the most significant from the i-butanol blend. The 12% i-butanol/7% ethanol blend was designed to produce no increase in gasoline vapor pressure. This fuel's exhaust emissions contained the lowest total oxygenates among the alcohol blends and the lowest NMOG of all fuels tested.

Changes in evaporation rate and vapor pressure of gasoline with progress of evaporation

The evaporation properties of motor gasoline are expected to change markedly with the progress of evaporation because gasoline is a multi-component fuel. The aim of this paper was to develop a prediction model of the amount of vapor generated from gasoline spill. The risks associated with gasoline spills can be accurately evaluated by the models. Degraded samples of regular gasoline and high-octane gasoline were prepared by leaving them under conditions of no wind at 20 °C, and their vapor pressures and flash points were measured. The evaporation rate was measured by determining weight loss using an electronic balance, and the relation between the weight loss fraction and the evaporation rate was investigated. “Weight loss fraction” was used as a parameter signifying the progress of evaporation and expressed the changes in vapor pressure and evaporation rate as a function of the weight loss fraction. The vapor pressure and the evaporation rate could be shown by exponential functions of the weight loss fraction, and a prediction model of the amount of gasoline vapor was obtained. Furthermore, the prediction model of the flash point of degraded gasoline was derived from the relational expression of temperature and vapor pressure, and the predicted flash points were compared with the measured values.

Effect of additives on the antiknock properties and Reid vapor pressure of gasoline

An evaluation was made of the effect produced by the addition of oxygenates such as ethanol, ETBE and MTBE and nonoxygenates such as isooctane and toluene on the Reid vapor pressure (RVP) and octane number of two types of gasoline with different chemical compositions. Locally produced gasoline was blended with five different percentages (v/v) of the additives, i.e. 5, 10, 15, 20 and 25%. Ethanol and MTBE increased significantly the RVP of the mixtures, but ETBE, and particularly toluene and isooctane, decreased the RVP of the original fractions when mixed with gasoline. The octane rating of gasoline was found to increase continuously and linearly with the addition of the oxygenated compounds toluene and isooctane. Moreover, the mixture octane number of the oxygenated compounds was superior to the octane number of the same compounds of high purity grade.

Mobile Source Emission Inventories—Monthly or Annual Average Inputs to MOBILE6?

In many urban areas, on-road vehicles are the biggest contributing source category of volatile organic compounds (VOCs) and nitrogen oxides (NOx). Based on a recently completed emission inventory study for three counties in central Florida, the major source by far of anthropogenic VOCs and NOx was on-road mobile sources, even though other sources (such as construction equipment, lawn and garden equipment, and various point sources) were also significant. Although there is specific guidance for conducting an ozone-season inventory for mobile sources, there is a lack of detailed guidance as to how to employ the U.S. Environmental Protection Agency's (EPA) latest mobile source emission factor program, MOBILE6, for an annual inventory. Several of the MOBILE6 inputs that significantly influence emission factors (e.g., temperature) can vary widely throughout the year, and the annual average value may not be appropriate. Rather, it may be better to utilize monthly values of these parameters. This paper investigated the sensitivity of the annual emission inventory results to using annual or monthly values of temperature, Reid Vapor Pressure of gasoline, and humidity. The results show that, for a three-county area in central Florida representing metropolitan Orlando, the annual emission inventory based on the sum of individual monthly averages is not significantly different from that calculated using one set of annual average inputs to MOBILE6.

Robust predictive control of a gasoline debutanizer column

This paper studies the application of Model Predictive Control to moderately nonlinear processes. The system used in this work is an industrial gasoline debutanizer column. The paper presents two new formulations of MPC: MMPC (Multi-Model Predictive Controller) and RSMPC (Robust Stable MPC). The approach is based on the concepts of Linear Matrix Inequalities (LMI), which have been recently introduced in the MPC field. Model uncertainty is considered by assuming that the true process model belongs to a convex set (polytope) of possible plants. The controller has guaranteed stability when a Lyapunov type inequality constraint is included in the MPC problem. In the debutanizer column, several nonlinearities are present in the advanced control level when the manipulated inputs are the reflux flow and the reboiler heat duty. In most cases the controlled outputs are the contents of C5+ (pentane and heavier hydrocarbons) in the LPG (Liquefied Petroleum Gas) and the gasoline vapor pressure (PVR). In this case the QDMC algorithm which is usually applied to the debutanizer column has a poor performance and stability problems reflected in an oscillatory behavior of the process. The new approach considers several process models representing different operating conditions where linear models are identified. The results presented here show that the multimodel controller is capable of controlling the process in the entire operating window while the conventional MPC has a limited operating range.

Customer Exposure to Gasoline Vapors During Refueling at Service Stations

Gasoline is a volatile complex mixture of hydrocarbon compounds that is easily vaporized during handling under normal conditions. Modern reformulated gasoline also contains oxygenates to enhance octane number and reduce ambient pollution. This study measured the difference in the exposure of customers to gasoline and oxygenate vapors during refueling in service stations with and without vapor recovery systems. Field measurements were carried out at two self-service stations. One was equipped with Stage I and the other with Stage II vapor recovery systems. At Stage I stations there is vapor recovery only during delivery from road tanker, and at Stage II stations additional vapor recovery during refueling. The exposure of 20 customers was measured at both stations by collecting air samples from their breathing zone into charcoal tubes during refueling with 95-octane reformulated gasoline. Each sample represented two consecutive refuelings. The samples were analyzed in the laboratory by gas chromatography using mass-selective detection for vapor components. The Raid vapor pressure of gasoline was 70 kPa and an oxygen content 2 wt%. Oxygenated gasoline contained 7 percent methyl tert-butyl ether (MtBE) and 5 percent methyl tert-amyl ether (MtAE). The geometric mean concentrations of hydrocarbons (C3-C11) in the customers' breathing zone was 85 mg/m3 (range 2.5-531 mg/m3) at the Stage I service station and 18 mg/m3 (range < 0.2-129 mg/m3) at the Stage II service station. The geometric mean of the exposure of customers to MtBE during refueling at the Stage I service station was 15.3 mg/m3 (range 1.8-74 mg/m3), and at the Stage II service station 3.4 mg/m3 (range 0.2-16 mg/m3). The differences in exposure were statistically significant (p < 0.05). The mean refueling times were 57 seconds (range 23-207) at the Stage I and 66 seconds (range 18-120) at the Stage II station. The measurements were done on consecutive days at the various service stations. The temperature ranged from 10 to 17 degrees C, and wind velocity was 2-4 m/s. The climatic conditions were very similar on the measurement days. Based on this study it was found that the Stage II vapor recovery system reduces gasoline emission considerably. The exposure level of customers at the Stage II station during refueling was circa 20-25 percent of the exposure at the Stage I service station when conditions were equal and no other confounding factors such as leaks or spills were present.

Measurement and Prediction of Reid Vapor Pressure of Gasoline in the Presence of Additives

Reid vapor-pressure (RVP) measurements of simulated gasoline with a variety of additives and fuel extenders, including alcohols, ethers, ketones, amides, amines, and esters, at different concentrations and 100 °F using a Setavap Vapor Pressure Tester 22420-3 are presented. Prediction of RVP of simulated gasoline in the presence of the different additives and fuel extenders has been performed using three UNIFAC-based models. Satisfactory predictions are obtained when nonassociating or weak associating additives are involved (average absolute errors in the prediction of RVP of the order of 1−2%), with the most satisfactory being the model of Gmehling et al. (Ind. Eng. Chem. Res. 1993, 32, 178−193). The results are poorer, however, for mixtures containing strongly associating additives such as methanol, ethanol, 2-propanol and 2-methyl-1-propanol (in many cases the absolute errors in the prediction of RVP were over 5%). UNIFAC models can be used for initial screening of potential additives, but actual effect...

Air Quality Model Evaluation Data for Organics. 4. C2−C36 Non-Aromatic Hydrocarbons

The concentrations of 143 non-aromatic hydrocarbons are quantified in 36 samples (32 urban and 4 background) collected during a severe Los Angeles area photochemical smog episode. Gas phase, semivolatile, and particle phase organic compounds are viewed simultaneously across the carbon number range from C_2 to C_(36). Compound classes studied include the n-alkanes, branched alkanes, n-alkenes, branched alkenes, diolefins, alkynes, saturated cyclic hydrocarbons, unsaturated cyclic hydrocarbons, biogenic hydrocarbons, petroleum biomarkers, and the unresolved complex mixture contained within the semivolatile and particle phase organics samples. The abundance of the n-alkanes falls almost exponentially with increasing n-alkane carbon number, and the distribution of the n-alkanes between the gas and particle phases follows vapor/particle partitioning theory. The concentrations of individual low molecular weight alkenes decline during transport across the urban area in about the order expected given their initial rates of reaction with the hydroxyl radical. Petroleum biomarker concentrations that act as tracers for particulate organics emitted from vehicle exhaust have declined substantially between 1982 and 1993, reflecting the increased penetration of catalyst-equipped cars into the vehicle fleet. The most pronounced change in vapor phase non-aromatic hydrocarbons concentrations between 1987 and 1993 is a reduction in the concentration of the lightest blending components of gasoline (e.g., butanes), reflecting new regulations that limit the Reid vapor pressure of gasoline.

Calculational method for determination of carburetor icing rate

This paper investigates the dependence of the carburetor icing rate on the density, distillation curve, and vapor pressure of gasoline. More than 100 gasoline samples, covering a range of volatility, were investigated. No clear-cut relationship can be observed between the carburetor icing rate and any specific property index of the gasoline. At the same time, there are certain variables that cannot be observed directly but can be interpreted readily through which the influence of gasoline quality on the carburetor icing rate can be explained. The conversion to these variables was accomplished with regard for the values of the variance and correlation of the carburetor icing rate. Equations are presented that may be used to predict the carburetor icing rate when using gasolines differing in quality. The equations can also determine the need for incorporating antiicing additives in the gasoline.

The determination of the vapor pressure of gasoline

The determination of the vapor pressure of gasoline