Year:2007 | Volume:41 | Issue:2 (104)|Papers Count:16

This study is about the non-uniform electric field for splitting of water in oil emulsion. If the process occurs in an inhomogeneous electrical field, the drops are polarized and then their mobility is increased.The emulsion drops will be charged and move toward the central point of splitter where the maximum intensity of electrical field has been concentrated. In this process, the drops encounter and form bigger and heavier drops, which are settled down due to gravity. Using the non-uniform electric method with 10500 Volt intensity, 50 Hertz frequency and 1 degree Celsius temperature, the 99 % splitting of emulsion was observed.

Up to now, the heat transfer coefficient for a number of non-Newtonian fluids in various combinations of vessel/agitator has been investigated. These types of fluids have a wide variety of applications and uses in the industry. Among these applications, exothermic polymerization reactions, production of resins and lacquers and many other applications require heat transfer to non-Newtonian fluids either for chemical reaction or for reduction of viscosity in the process. Therefore, knowledge of heat transfer coefficient in these systems is important in the design and operation of such systems. In the present investigation, using an experimental set up consisting of a jacketed vessel, a pitched turbine agitator with variable speed motor, a 2000 W electric heater situated in the middle of the vessel as the source of heat for the system and instrumentation, systems for the measurement of cooling water flow rate and local and bulk temperatures, heat transfer coefficient for non-Newtonian fluids has been measured. All thermocouples have bean calibrated according to BSEN 60751- 1996 standards and proved to have an error of ±0.1°C. Parameters such as the concentration of Zanthan gum in water (non-Newtonian fluid solution of 0.2, 0.3 and 0.5%) and the speed of rotation of the agitator (200, 300, 400, 500 and 600 rpm) have been varied and the findings of various experiments were noted giving special attention to the viscosity of the solution and its effects. A power law relation was derived for the apparent viscosity of the non-Newtonian fluid as a function of the rotation speed and the temperature. By the use of dimensional analysis, an empirical equation was derived relating Reynolds, Prandtl and viscosity numbers to the Nusselt number and hence the variation of heat transfer coefficient was indicated as a function of the most important operating parameters. The investigation included Reynolds number in the range 300 - 66000. Correlation is in the usual form of Nusselt number as a function of multiplications of Reynolds, Prandtl and viscosity number. The power of Prandtl number has been taken as 0.33 which is according to what has been indicated in most of the literature for similar cases. However, the power for Reynolds and viscosity numbers as well as the correlation constant was determined from the experimental data. The final from of this experimental correlation is Nu=0.935 Re 0.62 Pr 0.33 vi 182 This correlation shows a good agreement (over 90%) with the experimental data.

In the present article an energy distribution function of heterogeneous solid was estimated. Energy distribution function is an important characterization for heterogeneous adsorbent. An overall adsorption quantity for a heterogeneous solid is usually expressed by a first kind of Fredholm equation, which contains unknown distribution function and local adsorption isotherm as a kernel. The calculation of this distribution function is an ill-posed problem. The current article shows that the difficulties arising from the ill-posed nature of an adsorption equation can be overcome with the linear regularization method and inverse theory. Performance of the regularization method for calculation multipeak energy distribution functions' was examined in the present work. The results expressed with different charts and several random errors. The results showed that linear regularization method is very convenient for prediction of energy distribution function of heterogeneous solids. Furthermore, if a large amount of data at low pressure is available, the performance of this method would be very suitable.Therefore, in the most cases that some data have a large random error (about 50%), regularization method can predict the energy distribution function satisfactorily.

The Tagouchi method was used for providing the instruction of ultra-filter dairy membrane cleaning. The goal function with using of four undimentionalized parameter, i.e., water and milk serum flux, percent of protein and dry mass of permeate, as quality indicator of cleaning of cleaned membrane, was defined. As a result, basic cleaning solution was found as follows: 0.8% NaOH, 1.0% EDTA, 1.0% Sodium di Hydrogen Phosphate, 0.1% Sodium Carbonate and 0.2% SDS. Cleaning with this solution at first step for 90 min and at second step for 20 min in 50°C was found suitable. The optimum acidic solution was obtained as 0.3% Nitric Acid, 0.01% Phosphoric Acid and 0.15% Marlophen. Cleaning with this solution for 60 min at 30°C has serious effect on membrane cleaning. In addition, using of lipase and protease in cleaning operation was studied. The results showed that protease is 4.39% stronger than lipase. It is shown that the serious effect of protein components is more than oily components on fouling of dairy membrane.

The history of the well production rate is a useful source of data not only for the well production potential in the future but also for the reservoir characterization. The reservoir average permeability, reserve, drainage area and well skin factor can be estimated using decline curve analysis technique which is based on the Fetkowich method. The decline curve can be generated by analytical solution of flow equations in porous media. In order to use the Fetkowich method, several assumptions should be made such as constant bottom- hole well pressure, no acidization, no aquifer effect in the reservoir and the reservoir should be homogeneous. Since fluid flow equations in the fractured reservoirs are different than homogeneous reservoir, we need to know if the Fetkowich method can be applied in the fractured reservoirs as well.First, a hypothetical reservoir with real data was constructed having several production wells with constant bottom- hole well pressure and the decline curves were generated for the reservoir. Then, this decline curve was compared with the Fetkowich decline curve. In the present work, it was shown that a good estimation for the fracture permeability could be obtained by using the Fetkowich method. Finally, using a real heterogeneous reservoir data (Cheshmeh Khosh oil field), the reservoir permeability was determined with the Fetkowich method. Cheshmeh Khosh oil field is one of the Iranian carbonate fractured reservoirs in south-west Iran. Although this reservoir does not have the same conditions for using decline curve analysis, using some periods that the production rate is declining, a good estimation for some reservoir properties University College of Engineering, University of Tehran 3 can be made. Therefore, we need to determine the time decline period for each well and the data should be smooth. Since there was a good agreement between the calculated permeability and the permeability from well test data, it was concluded that the Fetkowich method can be applied in the fractured reservoir as well. However, these results are not trustable for skin factor determination.

This paper presents a study on estimation of heat transfer coefficient and thermal diffusivity parameters by use of analytical solutions and experimental data for regular geometries (infinite slab, infinite cylinder and sphere). Analytical solutions have a broad use in experimentally determining these parameters. These solutions, with use of experimental data, might give a greater advantage over use of other methods, e.g., the lumped system approach or empirical equations. In the present work, the method of finite integral transform (FIT) was used for solutions of governing differential equations.The temperature change at centerline location of cylindrical objects (Aluminum and Brass) were recorded to determine both the thermal diffusivity in a highly agitated water medium and heat transfer coefficient in air and water mediums. Then, with the known slop of the temperature ratio vs. time curve and radius of the cylindrical material, thermal diffusivity value or heat trartsfer coefficient may be determined. For all experiments, excellent agreement was obtained between the experimental results and the actual data. This method may also be used to find out the precise geometric location of the thermocouples placed in the samples to measure the temperature change. In this research, thermocouple location for a spherical object was determined. This technique would be much faster and easier compared to the other methods used for this objective.

Analysis of reservoir performance using material balance is a reliable method for the determination of original hydrocarbon in-place (OHIP) and the recovery factor using pressure and production history of the reservoir. In this study, first, different material balance methods in oil and gas reservoirs were investigated and their applications were described. Then, different production mechanisms were reviewed and some aquifer models which were applied in this work were presented. In the van Everdingen-Hurst model of aquifer, instead of using the table look-up, which is a cumbersome work, some polynomials were used with having negligible difference comparing to the values of tables. In order to perform all material balance calculations with high accuracy, user-friendly software was developed. The software has the capability to perform the history matching of reservoir pressure versus hydrocarbon and water production and also, the existence of water drive and abnormal pressure behavior can be detected. In the case' of abnormal pressure behavior, appropriate methods were applied. OHlP and aquifer parameters can be determined using nonlinear and linear regression. Production mechanisms are also determined using the calculation of drive indices. In order to validate the software, the data of both oil and gas reservoirs from Iranian fields were considered. The original oil in place for the oil reservoir was calculated to be 29200 MMSTB by our software compare to 29250 MMSTB by Mbal (commercial software). The original gas in place for the gas reservoir was calculated by the p/z and the modified p/z methods to be 20.95 TCF and 12.5 TCF while by Mbal were 21.15 TCF and 12.8 TCF, respectively. There are good agreements between the results from our software and other related software.

In this research paper, an experimental breakthrough curve for citric acid in an adsorption recovery process was determined by an ion-exchange resin in 20, 35, 55°C. Also, a mathematical model for breakthrough curve was presented. Among ion exchange resins that have been experienced, many weak and strong basic anionic resins are available such as, IRA-92, IRA-93, IRA-420 and IRA- 458 and all of them were experienced in this work. It was shown that IRI-93 has good performance and compatibility. To obtain concentration of citric acid in the outlet stream from the resin glass column, spectrophotometer DV-VIS, Cary 1E/ Cary 3E from Varian Company was used. The results indicated weak basic kinds are '"suitable for organic acids recovery, especially for citric acid. Also, the results showed that Amberlite IRA-93 is one of the best resins for recovery of citric acid. In the transient state adsorption, the breakthrough isothermal adsorption curve was obtained in different temperatures. Generally, although an increase in temperature causes an increase in diffusion coefficient of particles, the saturation capacity of resin (or the effective adsorption of acid in the bed) decreases. Several models in different forms, such as fractional, polynomial and exponential, were developed and with analyzing these models a new mathematical model in the form of C=at/b+c° and modified form of c at were developed for C/CF=at/b+(c/cf)n prediction of the breakthrough curve with low error. Also, if the model is to be used for the break through curve between start and terminal rapture points, the situation of fitting is in the best condition and error less than 1% could be achieved. In this way, least square method in Eviews software was applied. With using these models, the variation of similar breakthrough curves could be fitted, appropriately.

In this research paper, the amount of lactic acid recovery with adsorption process by strongly-anionic resins at 25, 30, 35, 40, 45 and 50°C were studied and also the effect of parameters in adsorption were investigated.Usual artificial ion exchange resin, are made on matrix non soluble long polymer, usually poly styrene, but some of these resins are based on Methacrilic Acid. Generally, IRA- 400, PVP-24, IRA-420, IRA-92 and Dowex- 50w are some of the important anion-basic resins and all of them were experienced in this research work. It is determined that IRI-400 has good performance and compatibility.Amberlite IRA-92 is an appropriate selection for lactic acid recovery as a weak basic resin. On the other hand, Amberlite IRA-400 is suitable one among strongly-basic resins. In the present work, the lactic acid adsorption isotherm in different temperatures was analyzed, and the best situation for lactic acid adsorption was observed in 45°C. Also, the best volumetric flow rate for resin washing with distilled water and normal sulfuric acid was 0.25 ml/min, totally. In addition, the effect of volumetric flow rate on the yield of acid recovery in DIL (=12/50) chromatographic column was studied. It was determined that removal of lactic acid in elution by distilled water is a quick process with lactic acid removal from solid surfaces approximately 60%. Then, elution of remained lactic acid (~40%) by sulfuric acid could be obtained with higher volume than utilized distilled water. The elution process was done by different volume flow rates. The results showed that using high flow rate of washing fluid could University College of Engineering, University of Tehran 5 affect the amount of required washing fluid and it was determined that optimum condition would be at the minimum flow rate of the washing fluid. For the situations similar to this experimental work, using 0.25 ml/min could be recommended. Generally, in the above optimum conditions, the efficiency of the recovery was 96% and the amount of productivity was 1.1 gr lactic acid in 1.0 gr resin.

Performance of a pilot Biofiltration system in removing of Triethylamine (TEA) vapor from air stream was evaluated in this study. Experiments were conducted with two 6-L three section biofilters containing a mixture of compost (60%) and wood chips (40%). The systems were operated at 20±2 and 30±1° C. Municipal activated sludge was added initially to promote microbial growth and the systems were started after initial adaptation period of 40 days. Various loading rates (8-130 g/m3 hr) and detention times (40- 60 seconds) were studied to evaluate the effect on performance of biofilter for TEA removal.Results indicated significant decrease in EC for HRT < 48 s but negligible differences were observed between 60 and 48 s. TEA removal in section one was significant higher than the other two. Maximum E.C. of 61 g/m3 hr at HRT of 48 second, humidity of 50-55 %, and loading rate of 90.6 g/m3. hr was observed for the reactor A. Maximum E.C. of  72 g/m3 hrat HRT of 48 s, humidity of 50-55%, and loading rate of 114.4 g/m3. hr was observed for the reactor B having a higher temperature.

Holdup was measured at various frequencies, amplitudes, continuous and dispersed phase flow rates for binary systems in a pulsed plate column capable of providing samples at various heights. The binary systems were so selected as to cover a wide spectrum of interfacial tensions. Dispersed phase holdup was found to increase with height in a logarithmic fashion at conditions away from the flooding point and to become almost invariant with height near flooding conditions.The interfacial tension of the binary system has a large effect on the dispersed phase holdup. In systems having low interfacial tension, a small increase in any of the parameters can increase the holdup significantly and lead to flooding. In systems having high interfacial tension, on the other hand, variations in system parameters do not affect system performance significantly.

Process control of a spray dryer that is usually used as the last step of production is very crucial in obtaining a quality standard product. To this end, predicting the effect of various operating and environmental parameters on product properties is essential. Modeling was done in microscopic and macroscopic scales by modifying the mass and heat transfer equations used in investigating the drying mechanism. However, as far as momentum transfer is concerned, the equations are the same as the ones used in the available literature models. Unlike conventional models that take only the two streams of hot air and sprayed droplets into account, a third stream is considered in our proposed model and this modification improved the results significantly. The model equations were solved numerically and new simulation software was developed using Visual c++ 6.0. The model results are in good agreement with the industrial data obtained from a detergent producing plant.

Feasibility of using Cyanex 301, as the auxiliary agent, for supercritical extraction of Cupper and Manganese cations from solid matrix was studied statistically. The amount of extraction is influenced by several parameters, such as amount of ligand, pressure, temperature, SCCO2 flow rate, time of extraction and amount of acid. Recent researches showed that factorial design is an effective tool for optimization of the operational conditions. A 26-3 fractional factorial design was used to derive the most effective parameters affecting the yield of extraction. Using analysis of variance and pooling method, the significant parameters were determined and separated from insignificant factors, and then main effects and their binary interactions were obtained. It was concluded that at high pressure (above 200 bar), the amount of acid, temperature and CO2 flow rate have significant effect on Cu extraction. The amount of the ligand showed positive effect on Mn extraction. As a result, it is possible to separate CU2+ from Mn2+ by SCCO2 at appropriate conditions from solid matrix more than 95%.