Mechanical Engineering

Ductile iron castings with 2 and 10 mm thickness with varying chemical composition were cast in sand molds to identify the effect of sample thickness on microstructural changes and tensile properties. The effect of melt chemistry and molten metal processing variables (i.e., pre-conditioning of the base iron, inoculation type and practice, and pouring temperature, etc.) on the tensile properties of thin-wall ductile iron castings has been investigated. Comparison of 2 and 10 mm sections within the same casting showed that section size was the main factor influencing tensile properties of ductile irons. While many samples from 2 mm sections showed low elongation values, likely caused by a high pearlite content or presence of carbides, many others showed higher elongations and superior strengths well above those required in ASTM A536 grades. At moderate to high elongations, the thin-wall samples were significantly stronger than samples from identical irons of 10 mm section.

This project design is embodied on a motorized tricycle for disabled Persons. The tricycle was specifically designed to suit wheelchair occupants of healthy Upper torso with pelvic to foot restraint. It is also designed to suit a commonly available Wheel chair. The level of relationship between the disabled people in the society has highly being jeopardized; therefore this project was designed to correct the difficulties in mobility of the wheelchair users. The main aim of the project design is to ease mobility for the physically challenged and also provide adequate comfort they desire. Existing tricycles for the disables requires the disabled person to dismount from the wheelchair onto the tricycle. The motorized tricycle in this project is designed to overcome this problem by allowing the disabled person to wheel up or down his wheelchair onto or down the tricycle. This is achieved using a specially designed platform that allows the wheel chair to be wheeled up or down. The prototype of this tricycle has been fabricated. The anthropometrics data that need to be considered in the design of the platform and frame of the tricycle have been taken into consideration at the design stage of the tricycle.

A design point simulation and adaptation of anindustrial GE LM2500+ gas turbine engine is presented. The design point is chosen when the engine runs steadily at operating point and close to the nominal design condition at 29MW power output. The targeted performance parameters are the fuel flow rate (FF), the compressor exit total pressure (P3), the compressor turbine total exit temperature (T8) and the total exit temperature from the compressor (T3). The values obtained from simulation using PYTHIA for the targeted performance parameters are 2.57%,-0.5%,-0.52% and 1.11% for gas path pressure deviations at thecompressor turbine, pressure deviations at the compressor, temperature deviations at thecompressor turbine, and temperature deviations at the compressor respectively. The average percentage deviation of the design valuesis over 1%. To achieve a better result, adaptation was carried out and the values obtained from simulation of the adapted values were-0.000035%, 0%,-0.00009%, and 0%. These values match reasonably with the targeted overall percentage deviation of 1%.

We present an off-design point analysis of a power generating gas turbine based on a reference location in Isle of Man. The off design simulation is carried out at, up to, an altitude of 2km for ambient temperatures range of 1 to 19 o C. A parametric analysis for the altitude simulations shows that power output and cycle efficiency reduced with an increasing ambient temperature while fuel consumption increased. The altitude simulation also shows that power output and mass flow rate reduce as altitudes increase, while the cycle efficiency reduces with increasing altitude. Degradation simulation was attempted by using a reduced fraction of the clean engine data and results show that power output was lower even at a higher shaft speed for a constant turbine entry temperature.

The continuous firing of a gas turbine engine make it become fouled with airborne contaminants like sand, dust, oil, salt and smoke which encrust the compressor and turbine components. Generally, the deterioration of axial flow compressors is a major cause of loss in gas turbine output and efficiency. The cleaning of the gas turbine compressor is the most effective method of preventing fouling. Cleaning maximises fuel efficiency, the life of the machine and recovers majority of lost power output. The most effective technique of cleaning the compressor and the air-filter of a gas turbine is the offline method. The technique includes injecting water into the compressor when the turbine is turned at cranking speed and requires the turbine to be shut down. This paper presents the performance evaluation of Geregu power plant gas turbine after a biannual maintenance operation. The performance parameters such as compressor pressure ratio, compressor discharge temperatures, turbine exit temperatures and power output improved significantly after the biannual maintenance operation. The generation utilization index increased from 0.55 to 0.90 andthe capacity utilization Index increased from 0.51 to 0.85 after the biannual maintenance operation. The station reliability index was 0.47 two months before the biannual maintenance operation but increased to 0.99 two months after maintenance, resulting to a total power generation increase from 66,000MWh two months prior to the biannual maintenance operation to 140,000MWh two months after the maintenance.

Refrigeration is the applied science which deals with reducing the temperature of a confined space and its content to a predetermined level that is below the ambient temperature. The design of a cooling table is presented. The cooling table is an innovative application in refrigeration system design. The table is a multipurpose table for maintaining a low product temperature whilst still being able to carry out other activities on the table like a conventional table. The design covers thecompressor, condenser, evaporator, table frame, table top, cabinet volume and the covers. The prototype design requires a 70W compressor for three participants.

Deep saline aquifers provide a large storage for CO 2. To ensure for long timescale storage, CO 2 is usually injected into the saline aquifers. It is important to understand how a storage will behave based on the injection rate of the CO 2 , such as knowledge of the gas migration pattern, saturation pattern among others. Selection of simulation tools usually depends partly on software capabilities. In this work, three computational applications (Eclipse 300, CO2STORE module, and Front Sim) were used with flow simulation of a ten year period at an injection rate of over 140,000 sm 3 /day. A recommendation is made of the application suitable for an oil field with likelihood of large pressure variation, gas breakout, hysteresis and imbibition.

A design point simulation and adaptation of anindustrial GE LM2500+ gas turbine engine is presented. The design point is chosen when the engine runs steadily at operating point and close to the nominal design condition at 29MW power output. The targeted performance parameters are the fuel flow rate (FF), the compressor exit total pressure (P3), the compressor turbine total exit temperature (T8) and the total exit temperature from the compressor (T3). The values obtained from simulation using PYTHIA for the targeted performance parameters are 2.57%,-0.5%,-0.52% and 1.11% for gas path pressure deviations at thecompressor turbine, pressure deviations at the compressor, temperature deviations at thecompressor turbine, and temperature deviations at the compressor respectively. The average percentage deviation of the design valuesis over 1%. To achieve a better result, adaptation was carried out and the values obtained from simulation of the adapted values were-0.000035%, 0%,-0.00009%, and 0%. These values match reasonably with the targeted overall percentage deviation of 1%.

This paper examines the application of Visual Basic Computer Programming Language to Simulate Numerical Iterations, the merit of Visual Basic as a Programming Language and the difficulties faced when solving numerical iterations analytically, this research paper encourage the uses of Computer Programming methods for the execution of numerical iterations and finally fashion out and develop a reliable solution using Visual Basic package to write a program for some selected iteration problems.

Department of Mechanical Engineering, Federal University of Technology, Minna, Niger State, Nigeria, [email protected], [email protected], [email protected] ... This work focuses on the design and construction of ...

Many farmers grow maize but could not afford the cost of acquiring some of the imported threshing machines because of their cost. Such people resort to manual means of threshing which results into low efficiency, high level of wastage and exerting of much labor. This machine was ...

Two similar solar drying units were designed, constructed and evaluated for drying basil leaves (Ocimum basilicum L.) as a medicinal and aromatic plant at initial moisture content of 590.73% (d.b) or 85.52% (w.b) under Fayoum conditions by using heated air. Each drying unit consists of a flat-plate solar collector, which oriented and tilted with an optimum tilt angle and attached with drying chamber. The drying experiments were carried out to examine the effect of basil leaves thicknesses (2, 4 and 6 cm) and airflow rate (0.015 and 0.025 m 3 .sec-1) on the basil leaves drying rate. The obtained results indicated that the daily average total solar radiation flux incident on the tilted solar collector surface (29.30 MJ. m-2 .day-1) was greater than that incident on the horizontal surface (24.30 MJ.m-2 .day-1) by 24.58%. The output higher air temperatures were obtained at the lower airflow rate whereas; the energy gained to the air from the solar collector was relatively higher at the higher airflow rate as compared with the lower airflow rate. Consequently, the solar collector with the higher airflow rate increased the overall thermal efficiency by 5.46% as compared to the lower airflow rate. The moisture content of dried basil leaves was strongly affected by the basil leaves thickness and the airflow rate. The final moisture content of dried basil leaves ranged from (11.52% to 14.58% d.b) depending on the drying temperature cycle. Very small changes were observed in the colour and shape of heated-air dried basil leaves as compared to that dried at direct sun rays. The essential oil contents of dried basil leaves were slightly higher for the drying unit with the higher airflow rate as compared with the corresponding values obtained from the drying unit with the lower airflow at all basil leaves thicknesses.

The effect of starch and gum arabic as binders in the combustion characteristics of briquette prepared from sawdust of different ratios was investigated. Briquettes of sawdust were produced by mixing with different binders and agglomerate using starch paste and gum arabic. The mixture was compressed at 110kN using manually operated hydraulic briquette machine and sun dried. Water boiling test was employed to obtain percentage heat uti- lized, specific fuel consumption and time spent to boil 1kg water. The calorific value, the volatile matter and flame temperature were determined. Results showed that the briquette formed using starch as a binder performed better in all aspect than the gum arabic.

The research work is on the possibility of producing lubricating oil from vegetable oil with palm olein as a case study. The sample analysed was obtained from Vandeikya Local Government Area of Benue State. Some of the physical and chemical properties such as viscosity, flash/fire point, pour point and specific gravity were analysed. This sample was bleached to remove the red colour (carotene) and gummy materials. The bleached sample was tested to determine the above mentioned properties. Comparison of the crude palm olein and the bleached sample with the conventional lubricants obtained from Elf Plc, Kaduna and Unipetrol Plc, Kaduna was made. Finally, it was discovered that the crude palm olein and the bleached sample exhibit a good base as a

Hydrocarbons are chemical compounds whose molecules are made of hydrogen and carbon. Heptane is an aliphatic hydrocarbon with good ignition quality and high cetane number, while Toluene is an aromatic hydrocarbon with a very poor ignition quality and very low cetane number. The two different compounds are blended in varying proportion and tested in a single cylinder 2.0L Ford Puma automotive diesel engine to investigate their effect on engine performance and emission. The cylinder pressure, heat release rate, exhaust gas emissions and particulate were measured. The results show that H70T30 blend has the highest specific NOX emission which was due to the high peak temperature and produces slightly more soot than pure heptane (H100T0). H50T50 attained the lowest heat release rate, peak cylinder pressure and temperature. These low values favour the formation of low NOx, high amount of unburned hydrocarbon and high amount of soot particles. Although heptane has a high cetane number, it ...

This study was carried out to design and fabricate a cost effective and efficient compression strength tester to carter for the needs of stakeholders in the blocks and bricks industries. In carrying out the project work a thorough study of the foreign testers and the requirements of the Nigerian industrial standards, NIS 87:2000 and NIS 74:1976 for blocks and clay bricks respectively was done. Design drawings and calculations were established and the machine was fabricated with well selected materials and components all sourced locally. The performance of the fabricated machine was finally evaluated against a standard foreign machine in the Standards Organisation of Nigeria using statistical methods and the result showed that the locally fabricated machine is 97 % effective.