Present study reports the effects of Operating conditions on the mixing of two co-axial streams. Produced mixing layers between the co-axial streams are investigated numerically in the developing regions. Closed form governing equations of the mixing layer flow are solved using Fully Implicit Numerical Scheme (FINS) and Tridiagonal Matrix Algorithm (TDMA). Calculations are made for the mean and turbulence properties, and spatial mixing deficiency (SMD). Obtained results show that increase in flow width does not correspond to increase in spatial mixing while increased level of centerline velocity, centerline concentration, mean vorticity, turbulent shear stress and turbulent kinetic energy (TKE) corresponds to increase in spatial mixing.

A method is presented to predict the onset of knock and associated performance of a spark ignition engine when primarily fuelled with gaseous fuels such as methane. It gives guidelines for choosing the best Operating conditions to obtain maximum power just before the onset of knock. A two-zone predictive combustion model was developed based on an estimate of the effective duration of the combustion period and the mass burning rate for any set of Operating conditions. The unburned end gas preignition chemical reaction activity is described by a detailed chemical reaction kinetic scheme. The variation with time of the value of a formulated dimensionless knock parameter K is calculated. This parameter relates the total energy released within the end gas due to autoignition reaction activity per unit of corresponding instantaneous volume relative to total energy release per cylinder volume that would take place normally due to regular flame propagation. When knocking is encountered, the value of K builds up to a sufficiently high value that exceeds an acceptable limit. Under normal Operating conditions, the value remains throughout the combustion period at comparatively low levels.

The essential role of surge arresters is equipment protection against overvoltages to increase system reliability. Different monitoring techniques have been used to diagnose surge arrester condition. Leakage current analysis methods by the extraction resistive and capacitive components of leakage current are a conventional method for surge arrester monitoring. Insufficient appropriate thresholds are most important restriction of these kinds of methods. In this paper, the impact of pollution, ultraviolet aging and varistors fault on harmonic spectrum of leakage current have been evaluated experimentally. Real tests and examinations have been done on different metal oxide surge arresters to investigate effects of mentioned factors on leakage current harmonics. To show results performance, bees-adaptive network based fuzzy inference system has been applied.

In this paper, results obtained from investigations on a polysulfon ultrafiltration membrane fouled by precipitation of milk components have been presented. Operating conditions such as temperature, pressure and crossflow velocity, which could play an important role in the fouling processes, were selected for the studies. Results show that dimensionless fouling resistance increase with increasing temperature and pressure and decreases cleaning agents on recovery of the fouled membrane has also been studied. Results show that a combination of sodium dodecyl sulfate and sodium hydroxide can be used as a cleaning material to reach the optimum recovery of the polysulfon membrane used in milk concentration industries. A mixture of sodium hypocholorite and sodium hydroxide shows acceptable results, while washing with any acidic material has no considerable result.

Diehylbenzene (DEB) dehydrogenation reaction was conducted to produce divinylbenzene (DVB) and ethylvinylbenzene (EVB). The effects of temperature, catalyst weight, and time factor on the performance of the dehydrogenation reactor were investigated experimentally. Temperature varied from 550 º C to 600 º C. Temperature affects the conversion of DEB to DVB significantly. By increasing the temperature from 550 º C to 580 º C, the mole fraction of DEB at the outlet of the reactor is decreasing; however, a further increase in temperature up to 600 º C does not decrease the mole fraction of DEB at the outlet of the reactor. Catalyst weight varied from 10 g to 40 g. The results showed that the trends of EVB+DVB production and DEB consumption were identical at various catalyst weights. To obtain an optimum time factor for the DEB dehydrogenation process, experiments were conducted at various time factors. The results showed that the optimum time factor for DVB as the desired product was 825 g/h. mol. The data and information provided in this research can be used for scale-up and optimization purposes.

This work attempted to determine the optimum conditions required for the coagulation and flocculation process as an essential stage of the ceramic wastewater treatment. Coagulation and flocculation is a very necessary step in industries as it lessens turbidity, color, and odor of wastewater. The experimental work was performed in several runs. The volume of wastewater used in each run was 200 mL and was kept at this value throughout. In certain runs, the speed of the mixer was varied while keeping the quantity of coagulant and flocculant constant in order to determine the optimum speed that resulted in the least turbidity. A speed of 5% was chosen as the ideal process speed according to the results obtained. Next, experiments were operated at this optimum speed while changing the dosage of coagulant and flocculant in order to decide the optimum dosage. Coagulant and flocculent amounts of 0.4 g (without booster) and 0.2 g (with booster) selected after the readings were taken. For all the readings, a turbidity meter was used providing results in Nephelometric Turbidity Units (NTU). Lowest turbidity was achieved when using 5% speed with 0.4 grams of coagulant and 0.4 grams of flocculant, or 5% speed with 0.2 grams of coagulant, 0.2 grams of flocculant and 0.25 g/L of booster coagulant. According to factorial design analysis, such as parameters as impeller speed and dosage have an influential impact on the turbidity; while the booster has insignificant influence and other interactions between parameters are important.

Flow behavior through a gas turbine double-container fuel valve is numerically studied. Normally the gas fuel supply pressure of the gas turbine sites is over 20+ barg while the combustion chamber pressure is around 12 barg in base load operation and slightly more than atmospheric during start-up. Therefore, the flow control through this high range of pressure ratios is a very difficult and costly task with a single-container control valve. The double-container valve is an innovative design which consists of two parts, SRV (Stop Ratio Valve) followed by GCV (Gas Control Valve), in a compact unit. SRV maintains a significantly low pressure upstream of the GCV during gas turbine firing to establish flame and control fuel flow during acceleration. It opens the GCV to a position where it is much easier to control the flow through the valve. The same situation exists in base load operation when the turbine load is changing. The obtained results prove the special design of the valve to maintain linear characteristics of flow with stroke position in GCV. The results of the mass flow are given for various GCV stroke openings at various valve pressure ratios. Also, the range of pressure ratios for a proper operation of GCV is determined. SRV regulates the middle pressure between the two parts based on rotor speed. Therefore, a sensitive combination of globes position takes place during gas turbine operation.