Engineering Mechanics Commons^™

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.

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.

Application Of Improved Pressure Transducers For Pressure Measurements, P Mtui

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

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 …

Quality Problems Facing Tanzanian Industrial Firms, M Msafiri

Tanzania Journal of Engineering and Technology (TJET)

This paper reports on the results of a study of quality problems facing Tanzanian industrial firms. The results show that Tanzanian firms do not set goals with respect to quality and quality management, thus their qual- ity performance is generally poor. A Ithough there are a number of opera- tional problems constraining the companies, the main problems lie with the internal management of the quality function. Extensive ideas and sug- gestions for improving the performance of the quality function are given.

Influence Of Turbulence On Methane-Air Flame Speed, E Mushi

Tanzania Journal of Engineering and Technology (TJET)

Experimental study Of the influence qfturbulence on flame speed for meth- ane-air mixtures has been conducted in afan stirred bomb using schlieren photography. It has been observed that turbulence increases flame speed but above KLe=O. 18 (KLe is the product Of the dimensionless Karlovitz flame stretch factor and the Lewis number) turbulence quenches the flame. Inminarflame kernel is observed to prevail in the early stages of flame development in a turbulent mixture. Further, the laminar burning velocity plays a significant role in turbulent combustion. It is proposed that the increase in flame speed is a result of flame wrinkling.

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, …

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 …

Practical Aspects In Sensing Vrm Magneti- Sation Characteristics For Rotor Position Detection, N Mvungi

Tanzania Journal of Engineering and Technology (TJET)

The detection of rotor position (stator/roror poles overlap) in a variable reluc- tance motor using the dependence of permeance on rotor position is the core of the effort to eliminate the need of a physical position sensor in the rotor shaft in the positional feedback operation of the motor. The reliability of the whole proc- ess Of eliminating the need of a physical sensor rests squarely On the ability to measure the instantaneous permeance ofa phase when the motor is in operation and at stand still. This paper presents an experimental investigation on the in- triguing problems of obtaining repeatable …

Optimum Design For Spring With Orthogonal Design Method, Han Fu - Jie

Tanzania Journal of Engineering and Technology (TJET)

Orthogonal design method is a sort of direct optimum method, by which the op- timal result may be obtained through simple computation and analysis. This method has gained increasingly extensive interest in scientific research, engineering design, end production management as well. The orthogonal table is the basic instrument for carrying out optimum design with orthogonal design method. It is a mathernatical table established On the basis Of the idea of isostatic distribution. As various levels may appear in any column, it makes a partial experiment contain levels of all factors furthermore. RII combina- tions of any two columns may appear …

Theoretical And Experimental Study Of Inlet Manifold Pressure Profiles Using Compensated Transducers, P Mtui

Tanzania Journal of Engineering and Technology (TJET)

Computer simulation and experimental findings on single cylinder four-stroke cycle engine were done with a view of getting more realistic inlet manifold pressures. Since there is a direct relationship between the inlet pressure profiles and the volumetric efficiency of the engine, then there is a possibility of utilizing the knowledge of these profiles to enhance better engine air flow characteristics and hence improvement of engine performance.

The simulation program is based on hometropic process with constant specific heats where the results were validated using experimental findings of the engine with varying engine speeds.

Experimental results are obtained by measuring manifold …

Comparative Study Of Inlet Manifold Tuning To Enhance Supercharge, Mtui L

Tanzania Journal of Engineering and Technology (TJET)

Computer model ing and experimental results on a single cylinder, four-stroke cycle engine for best air flow characteristic is The modeling analysis is based on hornet ropie fluid di scussed . The model n g resul s is flow w it. h constant: specific heats. included to val idat.e the s imulation program against experimental results with widely vary ing manifold lengths and engine speeds. ExperimenLal results are obtained by measuring air f low rates Lo the inlet valve during steady g Late speed Of Lhe engine. Manifold tuned lengths are Obtained for a range Of speeds by exper and …

Electrical Equivalent Method For The Calculation Of Vibrations In Transformers, D Chambega

Tanzania Journal of Engineering and Technology (TJET)

Noiselevel calculations may be done using an electrical equivalent method. So far a single mass and a double mass vibrating system may easily be represented by equivalent electrical circuits which are in turn useful for analysis. Multimass vibrating systems like transformers do not have straightforward methods which can enable analysis of noiselevels. This paper attempts to develop such a method by extending the method applicable to a double mass vibrating system. Then the validity of the method is tested using a transforme

Numerical Investigation Of A Non-Newtonian Material Through A Sudden Pipe Expansion, V. G. Masanja

Tanzania Journal of Engineering and Technology (TJET)

A numerical method for solving two dimensional elliptic boundary-value problems of fourth order is used for finding stationary solutions of the equations of motion for a laminar flow through a sudden pipe expansion of an incompressible non-Newtonian fluid with a constitutive equation of the Reiner-Rivlin (R-R) type. Results for the Newtonian fluid, which is a special case, are in excellent agreement with those by previous investigators and they demonstrate the reliability, superiority and accuracy of the method. Results for the non-Newtonian cases could be of value for fixing ideas about visco-elastic behaviour although the R-R fluid allows only inelasticity: this …

Simulation Of Fluid Flow In Packed Beds Using A Simplified Model And Network Analysis Technique, Haggai W.K. Sarakikya

Tanzania Journal of Engineering and Technology (TJET)

Abstract

A Reiner-Rivlin Fluid Flow Through Entrance Region Of A Circular Pipe, V. G. Masanja

Tanzania Journal of Engineering and Technology (TJET)

The flow of a Reiner-Rivlin fluid with two viscosity coefficients through the entrance region of a circular pipe has been studied numerically. In particular the growth of the entrance length as a function of the Reynolds number and the non-Newtonian parameters has been examined. Where comparison could be made, the results have been compared with existing experimental -and numerical data as well as the limited theoretical work available.

Production Of Blanking Circles And Dies - An Appropriate Method, V Bhandari

Tanzania Journal of Engineering and Technology (TJET)

A large important blanking die for production of multiwick stoves oil tanks was damaged beyond repair during normal maintenance. A replacement die could not be made available immediately. Initially an alternative blank production system based upon the adaptation of the inhouse and locally available tools was set up. Subsequently a temporary low cost and a permanent replacement blanking die was designed, developed and manufactured out of pad welding of mild steel plate. Recommendations have been drawn in light of the experiences gained in the deployment of these appropriate methods.

Towards The Development Of A Seed Minimum Tillage Planting, G Mutoizi

Tanzania Journal of Engineering and Technology (TJET)

Some advantages of minimum tillage compared to conventional tillage. systems are given. An evaluation of current minimum tillage planters is then made identifying two major problems namely the handling of trash. which detracts from making a continuous furrow of uniform depth, and unnecessary power Consumption When making this continuous furrow in spaced planting of seeds. Then the design, manufacture and development of a rig type of a seed injector for use in precision-drilling of a typical tropical geed is presented. It is to inject the Seed using rotary sleeve Valve in which is tractor drawn. Preliminary field testing of the …

Distributive Mixing Performance Of Rubber Internal Mixers, B Mutagahywa

Tanzania Journal of Engineering and Technology (TJET)

Results of experiments to study the distributive mixing performance of Internal mixers are reported in this paper. Distributive mixing was assessed by monitoring the uniformity of sulphur distribution throughout rubber mixes subjected to a range of rotor revolutions. The results indicate that distributive mixing in a well controlled Internal mixer is rapid and unlikely to be a source of mix variability.

An Electro Hydrodynamic Study Of The Negative Corona Electric Wind, Henry Thadei Kadete

Tanzania Journal of Engineering and Technology (TJET)

The velocity of corona generated electric wind is measured. From the velocity profile mass movement and electrokinetic conversion efficiencies are deduced. High speed schlieren photographs illustrate the form of the velocity distribution function as well as its high degree of turbulence.

Negative Corona Current Characteristics Of An Electric Wind System, Aviti Kadete

Tanzania Journal of Engineering and Technology (TJET)

The corona current characteristics of an electric wind system are investigated. First a brief summary of the negative point to plate corona mechanism and characteristics are presented. Then empirical equations for corona currents of an electric wind system are derived. Current waveform characteristics are also discussed. The effects of placing parallel rods in between a point-plate electrode gap to the corona currents are highlighted.

The Eccentric Disc Pitter Planter-A Soil Conservation Tillage Tool For Mechanized Farming., J Dumelow

Tanzania Journal of Engineering and Technology (TJET)

A planting technique which could enhance agricultural production is presented. The Edip planting technique which is discussed has low capital and operating costs. It also has reasonable and reliable yields as well as providing effective moisture and soil conservation.

Hydraulic Rams For Rural Water Supply Schemes In Selected Areas In Tanzania, T Mbwette

Tanzania Journal of Engineering and Technology (TJET)

This paper presents one of the many efforts made by the Faculty of Engineering and the Institute of Production Innovation of the University of Dar es Salaam towards the realization of the International Water Supply and Sanitation Decade. Special reference is made to the use of hydraulic rams along with some simple water treatment methods. Besides the account of theoretical and practical work done to-date in the field of water supply, a further evaluation of the theoretical model presented is recommended so as to enable a judgement of the present hydraulic ram designs to be done. Tests on a typical …

The Efficiency Of A Two-Edged Tool And Its Improvement, J. R. Masuha

Tanzania Journal of Engineering and Technology (TJET)

Abstract

Steel Making In Port Talbot Works Of British Steel Corporation, S. P. Mosha

Tanzania Journal of Engineering and Technology (TJET)

Abstract

Industrial Projects Recommended By The Faculty Of Engineering Udsm, W Kreuser

Tanzania Journal of Engineering and Technology (TJET)

During the assessment of the manuscript, it was observed that the paper does not include an abstract. The document proceeds directry to the main content without providing a separate abstract that summarize the study's objectives, methodology, key findings and conclusions

Plough Parts Production At Ubungo Farm Implements, F Kavishe

Tanzania Journal of Engineering and Technology (TJET)

During the assessment of the manuscript, it was observed that the paper does not include an abstract. The document proceeds directry to the main content without providing a separate abstract that summarize the study's objectives, methodology, key findings and conclusions