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Articles 121 - 150 of 157
Full-Text Articles in Chemical Engineering
Application Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Arton Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Art, Silas Kajuna
Tanzania Journal of Engineering and Technology (TJET)
Vibration is one of the techniques employed in the determination of dynamic properties of fruits and vegetables. It entails generation of a mechanical or acoustic vibrational signal which is propagated through the flesh of the agricultural material. A transducer is either attached or held close to the specimen to monitor the propagation of the signal through the specimen. The manner in which the signal is transmitted through the material is analyzed, and the dynamic properties of the specimen which relate to its firmness or its internal being are derived. The technique has been around for the past 30 years or …
Estimation Of Volatile Cloud Density For Single Coal Particles Using Microgravity Condition, H. Katalambula
Estimation Of Volatile Cloud Density For Single Coal Particles Using Microgravity Condition, H. Katalambula
Tanzania Journal of Engineering and Technology (TJET)
Single coal particle’s volatile cloud density has been estimated by employing a microgravity condition. The volatile yield was found to decrease with pressure while the density was found to increase, indicating that volatiles occupies less space when under pressure and hence causing some volatiles to be retained within the particle. The volatile cloud density was also found to increase with volatile yield suggesting volatile composition changes with yield. The effect of heating rate on volatile yield was found to be the same as reported by other investigators where the yield increased with heating rate.
The Effect Of System And Oxygen Partial Pressure On Single Coal Particle Heterogeneous Ignition Temperature Under Conditions Of Negligible Convection; Experimental Observation, H. Katalambula
Tanzania Journal of Engineering and Technology (TJET)
Abstract Under conditions of high volatile concentrations, the influence of oxygen concentration on single coal particle ignition becomes more significant. The high volatile concentration conditions have been simulated by employing a microgravity environment. Results show that under these conditions, the heterogeneous ignition temperature decreases faster with increasing oxygen concentration than under normal conditions. The ignition temperature also decreases with increasing system and oxygen partial pressure under both conditions. Generally, the system and oxygen partial pressure show similar and complimenting effects on ignition temperature.
Measurement Of Markstein Lengths In Laminar Spherical Explosion Flames, E .M.J Mushi
Measurement Of Markstein Lengths In Laminar Spherical Explosion Flames, E .M.J Mushi
Tanzania Journal of Engineering and Technology (TJET)
Schlieren photography was used to record the development of spherical flames in a combustion bomb. Flame speed and flame stretch were evaluated from the data and used to evaluate Markstein lengths and numbers. The results indicate a strong influence of both the spark discharge energy and equivalence ratio. Low spark discharge energy is observed to give rise to more unstable flames compared to high energy sparks. It is observed that for the range of energy tested, 80 and 400 mJ gave the best stability for the flames. For equivalence ratio less or equal to 1.225 an 80 mJ discharge results …
Production Of Fermentable Sugars From Waterhyacinth By High-Temperature Dilute-Acid Hydrolysis Method, J. H. Y. Katima
Production Of Fermentable Sugars From Waterhyacinth By High-Temperature Dilute-Acid Hydrolysis Method, J. H. Y. Katima
Tanzania Journal of Engineering and Technology (TJET)
A study on acid-catalyzed hydrolysis of Waterhyacinth (WH) biomass for production of monomeric sugars has been done. Waterhyacinth (Eichhornia Crassipes) plants were obtained from Lake Victoria. A yield of 18.5% w/w fermentable sugars was achieved during hydrolysis of oven-dried Waterhyacinth (ODWH) biomass at 220°C and 1.5% w/w H₂SO₄ acid. The waterhyacinth (WH) hydrolysates obtained from a high-temperature dilute-acid hydrolysis were rich in six-carbon (C₆) sugars (glucose) which could be fermented to ethanol. The production of fermentable sugars from waterhyacinth biomass is a promising new opportunity for its economic value which can in turn accelerate its rate of harvest and utilization.
Turbulent Burning Model For Premixed Gaseous Mixtures, E Mushi
Turbulent Burning Model For Premixed Gaseous Mixtures, E Mushi
Tanzania Journal of Engineering and Technology (TJET)
A turbulent burning model for premixed gaseous mixtures has been successfully developed. The model assumes instant burning of vortex Tubes of the order of Kolmogorov scale followed by burning of larger eddies of the order of Taylor micro scale. These eddies burn ar a rate dependent On the stretch rate. The influence of turbulence on the burning rate is introduced in the form of probability density function which gives the probability that a given mixture under turbulence will undergo burning rather than being quenched. The model has been validated againsi experiments involving turbulent explosions in a fan stirred bomb. Model …
New Technologies For Thermal Disposal Of Sewage Sludge, T Ogada
New Technologies For Thermal Disposal Of Sewage Sludge, T Ogada
Tanzania Journal of Engineering and Technology (TJET)
The traditional methods for the disposal of sewage sludge are landfilling, recycling as fertilisers in agricultural lands, dumping into sea and incineration. In thc recent past, Sludge incineration has been rapidly gaining ground duc to environmental constraints facing the Other methods. However, the cost of pollution control during sewage sludge incineration is currently very high due to the expensive flue gas treatment facility required. Futhermore, large quantity Of ash is produced which is highly contaminated with heavy metals and must be disposed off in special landfilling sites in order to avoid ground water pollution. To reduce the cost Of pollution …
The Significance And Effects Of Oil Injection On The Performance Of Sliding Vane Compressors., M Mkumbwa
The Significance And Effects Of Oil Injection On The Performance Of Sliding Vane Compressors., M Mkumbwa
Tanzania Journal of Engineering and Technology (TJET)
A computer model of a sliding vane air compressor was used to predict the behaviour of machines having different geometries operating at different conditions. The performance parameters which were calculated by the model were the free air delivery, power input and specific capacity which is defined as the free air delivery per unit of power input.The model also included the study of the effects of Oil injection on these mentioned compressor performance parameters. The paper describes the simulation model developed incorporating an analysis Of the effects of the oil injected into the compressor on lhe thermodynamic processes taking place in …
Experimental Study Of Domestic Charcoal Stoves, Simbo Kimario
Experimental Study Of Domestic Charcoal Stoves, Simbo Kimario
Tanzania Journal of Engineering and Technology (TJET)
The demand of fuelwood for domestic cooking especially the charcoal fuel is increasing in the urban settlements due to the increase in population of low income class earners who are the main consumers Of this type of fuel. This paper is presenting rhe results Of experiments conducted on the popularly used domestic charcoal stoves in Tanzania. The results revealed some significant differences on stoves performances. The type of insulation materials and some design features incorporated into the combustion chambers of the stoves had positive impacts in relative charcoal fuel saving. About two tons of charcoal fuel could be saved by …
Oxygen Transfer In A Three-Phase Fluidised Bed Bioreactor With Novel Biomass Support When Used In Industrial Wastewater Treatment, S Manyele,
Tanzania Journal of Engineering and Technology (TJET)
The effect of support mass and liquid height on the oxygen transfer in the three- phase fluidised bed were experi/nenta/ly investigated. Novel biomass support, rhe KMT*, with density of 850 kg/n/ and an equivalent size, dp 8.3 mm, has been used in this work. The oxygen transfer rate was expressed in terms of rhe volumetric oxygen transfer coefficient, kca. It has been found out that the* a values increased with increasing support mass up to a critical solids load of 4.0 kg, above which the kca decreased and that kca decreased with increasing liquid height. It has been recommended that …
A Study On Ring Pack Lubrication In Internal Combustion Engine, I Mshoro
A Study On Ring Pack Lubrication In Internal Combustion Engine, I Mshoro
Tanzania Journal of Engineering and Technology (TJET)
Most efthe lubricating oil from Internal Combustion Engine (ICE) is lost through piston rings. Hence, in order to optimally reduce ICE oil consumption, a better insight into tribology of the ring pack is required. This can only be achieved by an inwroved characterization of the lubricant behaviour within the opelating environment of the engine. In The present ieork, an optical tcchnique using laser- induced fluorescence was employed to measure oil film thickness within the ring pack. The experiment was conducted on a Phaser 1000 Series engine, whereby optical access to the ring pack was achieved by a fused silica-window positioned …
Design Considerations For A Three-Phase Fluidized-Bed Bioreactor, S Manyele
Design Considerations For A Three-Phase Fluidized-Bed Bioreactor, S Manyele
Tanzania Journal of Engineering and Technology (TJET)
The design Of a three-phase fluidized bed bioreactor using novel biomass support for industrial wastewater treatment is reported in this paper. A column of 0.20 m diameter with variable height up to 6.60 m equipped with a foam breaker tank was designed, commissioned and operated. A novel biomass support, KMTR support, has been used Separate gas and liquid feeding systems were designed to facilitate proper bioreactor operation. A flat distriburor plate with 4 mm holes- diameter was desined A study on the hydrodynamic properties of the three-phase fluidized bed bioreactor revealed high values of bed expansion and air hold-ups. Purification …
Use Of Dissolved Oxygen Concentration Probes In Biological Wastewater Treatment Plants, S Manyele
Use Of Dissolved Oxygen Concentration Probes In Biological Wastewater Treatment Plants, S Manyele
Tanzania Journal of Engineering and Technology (TJET)
A study on use Of dissolved oxygen probes (DOP) for measurement Of oxygen concentration in warer and wastewater treatment is presented. The principles Of operation, design considerations and selection criteria for Two types of probes, viz. galvanic and polarographic, are discussed Use of polarographic probes in n rhree-phase fluidized bed bioreactor and in laboratory experiments is presented and discussed. The effect of airflow rate and treatment time on dissolved oxygen concentration was found to be significant. It was found that polarographic probes are important equipment in determining the pollution of the industrial effluents. Finally, the use of the DOC probes …
Design Approach For Small Scale Continuous, Steady State Plants, O Kaunde
Design Approach For Small Scale Continuous, Steady State Plants, O Kaunde
Tanzania Journal of Engineering and Technology (TJET)
One of the major steps in the design of a process plant is development of an appiopriate flowsheet. At this step, the technical solutions may be con- sidered in relation to the social and economic factors. In this paper, guide- lines for developing a flowsheet for continuous, steady State process in a developing country environment have been proposed. To illustrate the pro- posed guidelines, a case study involving design of an ethanol distillation plant has been used.
Polymer Supported Z-N Catalysts For C2h4-Polymerization,I: Development Catalyst Preparation Method, S Mteza
Polymer Supported Z-N Catalysts For C2h4-Polymerization,I: Development Catalyst Preparation Method, S Mteza
Tanzania Journal of Engineering and Technology (TJET)
Substantial improvement of low sensitivity pressure transducers aiming at obtaining a more realistic output signal is discussed. The output signal direct from these transducers has deficiencies of amplitude attenuation and phase lag, thus the measured values are not necessarily the true in- stantaneous values. In order to correct for such shortcomings the unit step response of these transducers is also studied experimentally. A math- ematical model is established based on the experimental results to build up a compensation circuit which is then included in the instrumentation setup to eliminate these deficiencies. The effectiveness of the compensated transducer is demonstrated by …
Influence Of Arc Discharge Duration On Turbulent Mass Burning Rate, E Mushi
Influence Of Arc Discharge Duration On Turbulent Mass Burning Rate, E Mushi
Tanzania Journal of Engineering and Technology (TJET)
The influence of arc discharge duration on turbulent mass burning rate was investigated for turbulent r.m.s vglocities of u '=1.73 m/s and u'=4.5 nfs. Methane air mixtures were used at equivalence ratios ranging from 0.83 to / .25. Flame size was obtained through schiieren photography while the intensity Of CH chemiluminescence emissions was used to measure mass burning rate. A variable spark duration unit was used for ignition sparks and all the experiments were done in a fan stirred bomb. Discharge duration has no effect when the equivalence ratio is I. For higher values longer duration inoeases the burning rate …
Improved Heat Transfer By Means Of Steam Injection In A Shell & Tube Heat Exchanger, O Kaunde
Improved Heat Transfer By Means Of Steam Injection In A Shell & Tube Heat Exchanger, O Kaunde
Tanzania Journal of Engineering and Technology (TJET)
When designing a heat exchanger; one aims at attaining high heat transfer rates SO as to minimise heat transfer area and therefore the overall cost. This paper presents a method of improving the overall heat travsfer coef- ficient of a conventional shell and tube heal exchanger. The method in- volves injecting steam into the process fluid as it enters the heat exchanger thus effecting mixing of fluid as it travels along the exchanger Tests car- • ried out using this technique showed a significant increase in the overall heat transfer coefficient values.
Experimental Investigation On The Use Of Native Biomass As Biosorbents For Metal Pollutant Removal, R Litto
Experimental Investigation On The Use Of Native Biomass As Biosorbents For Metal Pollutant Removal, R Litto
Tanzania Journal of Engineering and Technology (TJET)
Waste water treatment is a perrnunent task. Many novel techniques have emerge in recent years and one of them is using biomass in removing heavy- metals. In this research screening and preliminary optimization experi- ments have identified different types of abundant biomass which can accu- mulate heavy metals such as Fe3*, C03•, Cu2+ and ftvm effluent. Cystoseira Myrica has a high uptake ofCr3+ while Sargassum Polycystum has been found to have a high uptake 0fFe3+. Observed biosorption kinet- ics shows rapid initial stage, followed by slower second stage and the amount of material adsorbed increases linearly as its concentration in …
An Alternative Method Of Interfacing A Dc Motor To A Microprocessor For Mo- Tion Control, M Selekwa
An Alternative Method Of Interfacing A Dc Motor To A Microprocessor For Mo- Tion Control, M Selekwa
Tanzania Journal of Engineering and Technology (TJET)
A Simple and cheap alternative method Of interfacing a permanent mag- net dc motor to a motion control using switch- ing transistor motor drivers is presented. This method involves the use Of very few transistor-transistor logic (TTL) devices and a 555 timer to pro- duce a pulse width modulated (P WM) signal which is required by the mo- ror driver. The motor driver in this case should be of an H-bridge type. Like other methods currently in use, it relieves the MPU of all timing func- tions which are necessary in the generation of P WM signals. The present method, …
Pulping Of Sisal Fibres: Effects Of Chemical Concentration, Na-Zs03/Na2c03 Ratio And Fibre To Chemical Ratio, J Katima
Tanzania Journal of Engineering and Technology (TJET)
This paper reports on pulping of hard fibres extracted from the leaves Of agave sisalana using sodium sulphite buffered with sodium carbonate as pulping chemical. The cooking was carried Out at 1680Cfor a cooking period of 6 hours, with varying chemical concentration, sodium sulphite to sodium carbonate ratio and fibre to chemical ratio. The results show thar boll! the pulp yield and pulp viscosity decæase with increasing chemi- cal concentration, whereas Kappa number of pulp decreases to a limit of about 16.45. Brightness increases significantly with an increase in the ra- rio of Na2S03/Na2C03. The pulp yield obtained indicated the …
Thermodynamics And Transport Proper- Ties Analysis Of Natural Gas From Songosongo In Kilwa- Tanzania, G Mrema
Thermodynamics And Transport Proper- Ties Analysis Of Natural Gas From Songosongo In Kilwa- Tanzania, G Mrema
Tanzania Journal of Engineering and Technology (TJET)
Analysis ofthermodynamics and transport properties was carried outfor six natu- ral gas samples from Songosongofield in Kilwa - Tanzania using PRO/II simula- for. Properties of most interest in gas processing (due to their influence on the sales value) such as density, specific gravity, critical parameters, bubble point and dew point, enthalpy, latent heat of vaporisation, molecular weight, boiling point and phase were investigated. In addition composition of the gas was com- pared with that from elsewhere. The gas was assumed to be at a temperature of 30C and a pressme of 150 bar before pressure let down station. Results indicated …
Improvement Of Solar Salt Works Performance, J Katima
Improvement Of Solar Salt Works Performance, J Katima
Tanzania Journal of Engineering and Technology (TJET)
Coal, asphalt, black oil paint, naphthol green b and alkali blue 6b were testedfor improvement Of solar energy utilisation in solar salt manufacture. It was found that the use of alkali blue 6b dye dissolved in raw seawater improves efficiency by 3.6 percent. Both modifications could increase solar salt works with a coal coated surface than one employing raw seawater dyed with alkali blue 6b.
Development And Testing Of Locally Produced Natural Rubber (Nr) And Pvc Blends, B Mutagahywa
Development And Testing Of Locally Produced Natural Rubber (Nr) And Pvc Blends, B Mutagahywa
Tanzania Journal of Engineering and Technology (TJET)
The mechanical properties of natural rubber - poly(vinyl chloride) blends have been studied. Tensile and tear strengths of the vulcanizates has been shown to increase with increasing proportions of PVC up to about 20 pphr. Abrasion loss and hardness decreases slightly with increasing concentration of PVC. Increased loading Of carbon black lowers the tensile and tear strength while increasing the abrasion loss and hardness values. This may be explained by the fact that PVC exists as a discontinuous rigid phase in the polymer compound. At normal loading of black (37 pphr) PVC improves processability and acts in the same way …
Energy From Biomass: Combustion And Gasification, G John
Energy From Biomass: Combustion And Gasification, G John
Tanzania Journal of Engineering and Technology (TJET)
Some fundamental facts of the combustion Of BIOMAS are outlined and di scussed . It is suggested that these provide guidelines for rhe development Of successful practical combustors. Furthemore, a realisation Of energy conversion from the same in gasfier is presented.
Nn Investigation Of Nitrogen Oxide Abscwption In Packed Columns, J Katima
Nn Investigation Of Nitrogen Oxide Abscwption In Packed Columns, J Katima
Tanzania Journal of Engineering and Technology (TJET)
An experimental study was carried out on the performance of a packed column to study the absorption mechanism of nitrogen oxides (NOx). Two packed columns were set up, one with wall wiper rings to reduce wall effects and one without. Both columns were packed with stainless steel lessing rings and operated at fixed gas and liquid flow rates (40 and 8 L/min, respectively), atmospheric pressure, temperature (25°C), and sodium hydroxide concentration (8% w/w). The NOx (NO₂ and N₂O₄) equilibrium concentration and feed concentrations of up to 7000 ppm were used. The results indicated improved performance in the column with wall …
Nitrogen Oxides Rbsorption Into Sodium Hydroxide Solution In A Packed Column Column: Effect Of Naoh Concentration, J Katima
Tanzania Journal of Engineering and Technology (TJET)
Experiments have been conducted to evaluate the ettect of sodium hydroxide (NaOH) concentration upon the absorption rate of nitrogen oxides (NO ) and packed column performance. The absorption process using was carried out at atmospheric pressure and 29B K, concentrations between zero and w/ w, NO/ NO ratio of 0.5 and NO concentrations between 150 and 10000 ppm in an air mixture. The performance of the calumn was enhanced by the presence of hydroxyl ions ( 0B - ) relative to the absorption into water, however, The absorption it was found to be independent of NaOH concentration. rate of NO …
Density Measurement For Corrosive Solutions At Elevated Temperatures, Kimweri, H
Density Measurement For Corrosive Solutions At Elevated Temperatures, Kimweri, H
Tanzania Journal of Engineering and Technology (TJET)
In this work, apparatus for measuring densities of corrosive solutions at high temperatures was developed and used. Densities of dilute aqueous sulphuric acid solutions, containing different amounts of zinc and iron salts were measured at temperatures up to 185°C. In view of the good agreement between consecutive measurements for each solution and the density of water obtained by using this apparatus with that given in literature, for all experiments, the apparatus is recommended to be used for measuring densities of corrosive solutions at high temperatures.
Effects Of Feed Solids Concentration On Dual Functionality Of A Hydrocyclone., Zanzu M
Effects Of Feed Solids Concentration On Dual Functionality Of A Hydrocyclone., Zanzu M
Tanzania Journal of Engineering and Technology (TJET)
The dual functionality, i.e. thickening and classification of a 50.8mm diameter hydrocyclone has been investigated. A metallurgical slime consisting of a 50% mixture of quartz and petroleum coke was used in the tests. It was found that in order to achieve both thickening and classification at the same time, the pressure drop across the hydrocyclone, the underflow diameter and the feed solids content have to be subtly controlled.
Absorption Of Nitrogen Oxides Into Sodium Hydroxide Solution In A Packed Column: Effect Of Gas Flowrate And Temperature, J Katima
Tanzania Journal of Engineering and Technology (TJET)
The effect of gas flow rate and temperature on the absorption rate of nitrogen oxides (NO ) and column absorption eff iciency has been studied using a 2M goåium hydroxide (NaOH) solution in a packed The absorpt ion process was carried out at atmospheric column. pressure, with NOV concentration ranging between 150 and 10000 pp:tt, NO/N02 ratio of O and 1 iquid flow rate of O .8 1/ min. The gas flow rate was varied from 20 to 60 1/17 in and the temperature from 25 to 45 c. It was found that Ehe column absorption efficiency increases with decreasing …
Investigation On The Use Of Ethyl Acetate As Solvent For Seed Oil Extraction, E. L. Rivera Porras
Investigation On The Use Of Ethyl Acetate As Solvent For Seed Oil Extraction, E. L. Rivera Porras
Tanzania Journal of Engineering and Technology (TJET)
An investigation on the use of ethyl acetate as a solvent for the seedoil industry was carried out. As hexane is the most used solvent in extraction of oil from seeds, the study focuses on the comparison of the two solvents. The parameters studied were: contact time between solvent and seed cake, temperature of the solvent, quantity of solvent used for extraction and type of solvent. The results are presented on a relative basis where hexane is given a factor of 100. From the results obtained it can be seen that ethyl acetate is in general a better solvent than …