Spreading wood particles and attached colored materials in work places can cause many problems for woodwork industry workers. The aim of this study is to design and implement a local exhaust ventilation system to control wood dust and isocyanates simultaneously.
The study was conducted on 18 workers in the paint workroom of a wood door industry. At first, an overview of the workplace indoor air was done in 18 workstations. The National Institute for Occupational Safety and Health (NIOSH) method was used to measure the concentration of wood dust and TDI(2,4-toluenediisocyanate). In order to control the worker exposure to the pollutants, a semi-downdraft spray chamber was chosen and implemented on the basis of American Conference of Government Industrial Hygienists (ACGIH) control air pollution method. Orifice scrubber was used to avoid entry of pollutants into the environment. Finally, after the establishment of a new ventilation system, the emissions were remeasured and the results were evaluated.
Before design and implementation of local exhaust ventilation system, the emissions in workstations were measured as 0.0015 ± 0.0074 ppm for TDI and 0.01 ± 0.42 mg/m3 for total dust. Then, the pollution concentrations were measured after implementing the local exhaust ventilation system. The concentration of TDI and total dust were measured respectively as 0.007 ± 0.003 ppm and0.07 ± 0.15 which had a significant (p˂0.05) lower concentration than before the implementation. Also, the measured concentrations after the implementation had met the National Institute of Occupational Safety and Health limits: (TLVTWA = 0.005ppm for TDI and TLWTWA = 0.5 mg/m3 for total dust).
The result shows that the current ventilation system (before implementing and spray chamber) was suitable for dusts, but not for the TDI. So, the workers were exposed to non-standard levels of isocyanate. After design and implementation of the spray chamber, the pollutants were clearly decreased (P

The use of diesel engines day by day increased because of their low fuel consumption and high performances. Common rail diesel engines with electronic fuel injection can accurately meter the fuel injection quantity and fuel injection pressure. Injection spray pressures in diesel engines play an important role for engine performance and emissions obtaining treatment of combustion. In this paper, effects of fuel injection pressure and spray cone angle on the exhaust emissions of a national diesel engine have been numerically investigated using a model verified by experimental data. In this study, four fuel injection pressures of 1000, 1400, 1600 and 1800 bar and three spray cone angle of 15, 25 and 35 degrees at 1400 bar injection pressure were investigated. The simulation results showed that by increasing the fuel injection pressure, the maximum pressure inside the combustion chamber increased from 144 to 162 bar and the temperature inside the combustion chamber increased by 8.2% and changed from 1607 to 1740 K. Subsequently, the amount of NOx produced also increased. But the amount of soot decreases with increasing fuel injection pressure due to better mixing of fuel and air. Changing the spray cone angle from 15 ° to 35 ° decreased the pressure inside the combustion chamber from 157 to 152 bar. One of the reasons for this decrease was the impact of fuel droplets against the walls of the combustion chamber at higher spray cone angles, this causes the fuel to not completely vaporize. An increase in the temperature of the combustion chamber was observed at a cone angle of 15 ° C relative to 35 ° C from 1654 to 1718 ° C. An increase in the temperature of the combustion chamber was observed at spray cone angle of 15 ° relative to 35 ° from 1654 to 1718 K.

The novel diesel engines with advanced fuel injection systems are equipped with solenoid injectors comprising multiple small nozzle orifices which makes considerable improvement in fuel spray characteristics and engine performance along with providing high pressure fuel injection system. On the other hand, poor fuel quality, impurities and heavy metal elements in the diesel fuel, and high temperature medium in the diesel engines combustion chamber lead to remarkable deposits formation in the small holes of the nozzle. In addition, it results in partial or complete nozzle hole obstruction which is called injector nozzle coking having detrimental effects on discharged spray ideal behavior and proper engine performance. In this work, the analysis of coking phenomenon influences on diesel spray macroscopic characteristics have been done. Initially, the coked injectors with different time operation and deposit amounts are prepared under experimental and specific operating conditions. Then, the images recorded from the spatial and temporal evolution of a diesel spray in various injection and chamber pressures, are processed through the extended code in MATLAB software in order to analyze discharged fuel spray characteristics. The SCHLIEREN Imaging Method with high speed camera has been utilized in a CVC (constant volume chamber) without combustion. Non-Destructive Electron Microscopy Method of SEM (Scanning Electron Microscope) imaging was utilized in order to analyze sediments quantity and construction changes during injector working in the real engine conditions. The results show that, sediments occupy 20, 40, 75 and 90% of the total hole opening surface, respectively in the injectors with 300, 700, 800 and 900 hours operating time. By increasing the injector operation time and accumulated sediment amount on the nozzle, the discharged injector spray exhibits a more inappropriate behavior. Moreover, The Results revealed that coking has considerable effects on the spray tip penetration at low injection pressures. As injection pressure increases, the decreasing rate of the penetration length alleviates gently. In other words, at high injection pressures (1500 bar and higher) the penetration length has minor drop compared with non-utilized injectors even at 900 hours operating time, but the spray projected area can be reduced up to 28% in high chamber pressures.

In the present work, the injector of a gas turbine is simulated using computational fluid dynamics. The penetration length of the injector under certain conditions has been validated by the results of laboratory tests. Then, the effects of turbulence model type, spray parameters on fuel penetration length due to change of spray pressure, spray cone angle, pressure, and temperature of the combustion chamber are investigated. The amount of evaporated fuel at different temperatures and the jet width of the fuel at different spray pressures is presented as an innovation of the paper. The results showed that increasing the injection pressure increased the penetration length and jet width of the fuel and also with increasing the spray cone angle and increasing the combustion chamber pressure, the penetration length decreased. With increasing ambient temperature from 300 to 450 K, evaporated mass of the fuel has increased. The jet width of the fuel is increased by 2, 3, and 4 times the spray pressure.

Better performance and the regulatory requirements concerning combustion emissions have caused downsized GDI engines and consideration of strategies for improving in-cylinder mixture preparation. The sprays characteristics of the fuel injectors of GDI engines have been widely investigated by researchers. The interest in studying the characteristics of the spray is due to a strong relationship with the subsequent combustion reaction and thus with the engine's thermal efficiency. This paper analyzes the mixture formation of the spray employing an experimental laser apparatus that was used to measure the spray penetration in a constant volume chamber (CVC) and simulations performed by the fast response CFD CONVERGE software. The fuel injector used in the tests was a six-hole direct injection injector with iso-octane fuel. The measurements were taken 100 mm downstream from the injector tip along the axis with 20 MPa injection pressure. During experiments, it was observed that spray development is not symmetrical with the vertical axis, and with decreasing chamber pressure, it develops faster. Moreover, the average spray development velocities in simulations are in good agreement with experimental results.

Clopyralid is an important herbicide for controlling the broadleaf weeds in sugar beet fields, but the effect of spray volume and soil settled on the shoot of weeds on its efficacy has not been studied yet. Therefore, a greenhouse study in factorial design (3×2×5) based on completely randomized design was conducted. The first factor included the amount of soil settled on jimsonweed foliage (0, 20 kgha-1 via a dust chamber, and 20 kg ha-1 via muddy rain), the second factor composed of airflow before spraying (0 and 6 kmh-1) and the third factor included spray volume (120, 240, 360, 480, and 600 lha-1). In the absence of soil on the shoot, the highest level of jimsonweed control (> 94%) was obtained with the use of clopyralid at 120 l ha-1. Under the same condition, the efficacy of clopyralid decreased with increasing the spray volume. In the presence of soil on the shoot via both methods, the lowest level of jimsonweed control (25%) was obtained with the use of clopyralid at 120 lha-1. Under the same condition, the efficacy of clopyralid increased with increasing the spray volume. At all spray volumes (except at 120 lha-1), the negative effect of soil settled on the shoot of jimsonweed via muddy rain was greater than dust chamber. Flowing air before spraying was only useful when the source of soil settled on the shoot of jimsonweed was dust chamber. In the presence of soil on the shoot of weed, more spraying volume, but in the absence of soil, low spraying volume is recommended for the use of clopyralid.

In the internal combustion engines geometry of the injector orifice has significant effect on the improving of the fuel spray characteristics. In the present paper, effect of a conical annulus injector with three different aspect ratios and three different divergence angles of the annulus orifice on the hydrodynamic behavior of a fuel spray have been investigated numerically. The conical annulus injector aspect ratio is the ratio of the height of the annulus cone to the diameter of its circular base. The geometry of the annulus conical injectors inspires this idea that this type of injectors could inject possible large amount of liquid fuel into a combustion chamber symmetrically and homogeneously. The CFD software AVL Fire has been employed for numerical simulation of diesel fuel spray evolution. Numerical results show that the annulus conical injectors inject liquid fuel with an approximately homogenous distribution of droplets in the combustion chamber in comparison with the conventional injectors. In this kind of injector, fuel has been uniformly distributed in the cylinder. Numerical results also show that the annulus injectors significantly increase the cone angle of the liquid fuel spray and decrease its penetration length.

This article discusses the importance of using different turbulence modulation models in simulation of evaporating sprays. An in-house CFD code has been modified to take into account the effect of considering turbulence modulation by standard or consistent models. These models may predict an augmentation (consistent model) or a reduction (standard model) in the turbulence kinetic energy of continuous phase. Calculations are done in a Eulerian-Lagrangian framework and the effect of injected droplets on turbulent kinetic energy and its rate of dissipation is included in the equations of the continuous phase. Results are shown to be valid by comparing them to Sandia spray A configuration experimental data. Results show that considering the effect of existing droplets in a turbulent combustion chamber can play a major role in having a more accurate CFD simulation. These models can alter the velocity field drastically when droplets are injected into the chamber with a high velocity. As a result, spray characteristics such as evaporation rate is also altered. It can be concluded that modulation models should be used in the simulation of evaporating sprays in order to attain more accurate and realistic results.

High pressure amount of fuel in new generation diesel engines’ injector equipped with multiple and small nozzle holes has created significant improvement in the outgoing spray behavior and engine performance. On the other hand, poor fuel quality and injector nozzle embedded in high temperature combustion chamber form fundamental deposits on the nozzle leading to fuel spray inappropriate behavior. Regarding the engine functional characteristics close correlation with fuel outlet spray behavior, in this study, the destructive effects of the fuel flow interaction with injectors nozzle sediment have been analyzed in terms of injector different operating time. The deposition process of injectors is carried out with standard fuel under specified experimental circumstances. Non-destructive electron microscopy methods have been used to analyze the sediment characteristics formed on the injectors nozzle. In order to analyze the outlet fuel spray characteristics, the spray evolution images of injectors with different operating time are processed by the code provided in MATLAB software at different pressures of the constant volume chamber and fuel injection. The imaging process was carried out in a constant volume chamber with a high speed camera. the injector deposits intensification increases the fuel injection delay and deteriorates the injector outlet spray behavior. The spray deposit destructive effects are alleviated through increasing the fuel injection pressure.

with developing of optical technologies, using of different imaging methods to study various properties of gasoline direct injection spray is under development. Scope of this article is  to study the effect of overall spray angle and spray projected area for determination of spray propagation and investigate the effectiveness of this criterion.  The injector was a multi-hole direct injection injector and for producing of the required injection pressure the accumulator type fuel injection system was designed and built and employed in the experiments. According to empirical study, it was found that the spray overall angle characteristic is not an appropriate criterion for measuring the spray propagation. the spray projected area also was investigated and it was found that this characteristic is a correct criterion for measuring the spray propagation especially for the multi hole GDI injectors spray. The Schlieren method was used for spray imaging and the spray projected area of image was extracted using image  processing technique. The propagation of the spray was also investigated for different chamber and injection pressures, which resulted a decreasing and increasing procedure in propagation with increasing environmental and injection pressures respectively. Also, investigation of the spray for chamber pressures less than the atmosphere pressure comparing with higher than atmosphere pressures, showed that at pressures less than the atmospheric pressure, the speed of spray propagation increases with increase of injection pressure, while at pressures More than the atmosphere pressure, this speed is almost constant.