Effects of Pouring Temperature on Solidification Using Energy Profile Analysis on Aluminum Alloy

This work covered the study of energy profiles as influenced by solidification on sand cast 6063 aluminum alloy. Temperature is an important parameter, most especially in foundry technology that influences properties and morphology of cast products. Different pouring temperatures of 680oC, 740oC and 780oC were considered. Mechanical energy expended and the quantity of heat evolved was evaluated from results obtained from tensile test experiments carried on the three samples. Relationship between change in coefficient of thermal expansion and change in applied tensile load were derived; it was observed that the maximum energy expended before fracture for samples decreased with increasing pouring temperature. Increasing pouring temperature decreased the amount of energy to be expended during deformation. This also influenced the change in heat evolved per time

Thermodynamics Characterization of Density models for an Effective Solar Water Heater Sizing

The problem faced in Sizing of an effective Solar Water Heater (SWH) by engineers to meet certain design requirement is highly enormous. Using the thermodynamic characterization relation and the knowledge of Solar Water Heater (SWH) density’s model; various design were evaluated. The result shows that density model actually predicts adequately and providing alternative means of estimating these design parameters. Also, the properties of the system, such as entropy and enthalpy (specific heat capacities), which cannot be determined directly from experimental axiom, were evaluated. These evaluations therefore, give room to express the thermodynamics properties of the system and consequently improve the design performance. Further comparisons with experimental results reveal a better outfit. Therefore through the knowledge of thermodynamic relation an efficient Solar Water Heater is operated and empirical data is expanded

Dynamic Crystallization: An Influence on Degree of Prior Deformation and Mechanical Strength of 6063 Aluminum Alloy

This research is aimed at investigating the influence dynamic solidification of melts on degree of mechanical deformation and mechanical strength of 6063 aluminum alloy. Cylindrical samples of 14mm diameter and 140mm long were die cast following two techniques – vibration and static. Prior deformation via forging was imposed on each solidified sample to achieve 7%, 14%, 21% and 28% thickness reductions respectively for each casting technique. Average deformation load, average hammer velocities and the average energy absorbed were recorded. Tensile properties of each sample were studied via the use of Monsanto tensometer. Mechanical agitation of mould and its content increased the machinability of the alloy even at higer pre deformation. This was justified by the failure of the 28% reduction sample cast on static floor during machining to a tensile piece. The energy absorbed during deformation influences the tensile strength of the material. This increases with increase in percentage deformation except for 28% reduction whose magnitude was lower than that subjected to 21% reduction; vibrated samples possessed superior properties. From results obtained, vibrating a sample and subjecting to 21% pre-deformation possessed the best tensile strength

Carbondioxide Electricity Generation Prospect in Nigeria

The need to meet up with the present energy demand in Nigeria calls for urgent mediation. Using the carbon dioxide data obtained from IEA through the ministry of Environment in Nigeria and the knowledge of bottoming power generation; the ability of Carbon dioxides exhaust gas from the power plant is exploited. Qualitative amount of power is estimated from the nation industrial Carbon dioxide potential generation. The result shows that an optimum amount of 564.7MW of electricity per year could be estimated from this power source; this is equivalent to 10.8% of projected power required for year 2030. Therefore, using Carbon dioxide hybrid turbine a total amount of 1265MW of electricity could be spawned by year 2030. With these results it is concluded that Carbon dioxides powered turbine has better prospects in Nigeria energy needs. 1.0 Introduction The electricity demand in Nigeria is far outstrips its supply, this has been attributed to a number of causes Sambo, (2008). The little power available is epileptic in nature for few locations that is distributed. Its enormous needs in technological and socio-economic developments called for urgent attention; no substantial development could occur without it copiousness. Despites our huge resources and potential for power generation, this defect has made the development in the country to be so retrogressive. The fact that the first electricity installed in Nigeria is over a century, coupled with our potentials of having a stable power supply is enough to possess a developed steady economics. More so, literature had it that the electricity came to Nigeria just after fifteen years it was introduced in England. According to Sambo, (2008) various bodies were established in the process of regimenting this sector such blocs are; The Electricity Corporation of Nigeria (ECN) in 1950, Native Authorities and Nigeria Electricity Supply Company (NESCO), Niger Dams Authority (NDA), National Electric Power Authority (NEPA) and now Power Holding Company of Nigeria (PHCN), Energy Commission of Nigeria (ECN), with all the policies of these established bodies the power generation in the country is yet to be upright. In fact, Osueke and Ezeh, (2011) emphasized that instead for positive income elasticity demand Nigeria is having negative which show an in balance energy Furthermore, a capacity of about 5,600MW power generating station was installed in Nigeria but less than 2000MW is generated as at 2001 and even now less than 2,600MW is available as compared to a load demands of 6,000MW and 120000MW in 2005 and 2030 respectively IAEA/ECN, Osueke and Ezeh, (2011), IAEA/ECN, (2007). The mandate given by act 19 in 1989 gave strategic planning and co-ordination of national policies in the field of energy in all its ramifications. In all these power sources 31.3% and 68.3% Sambo, (2008) were for hydro and natural gas stations respectively and other occupied the remaining percentages. In spite of all these efforts the available power in the country now is less than 3000MW of electricity and the most of this power stations and other heavy duties industries give out huge emission of CO2, a green house gas, GHG, which has great effects on the environmental conduciveness. Sims et al (2007) studied the various sources of green houses gases and found out that over 70% of energy generation emit CO2 virtually in all parts of the world. Though most developed nations adopt different methods to control these like capturing methods but scientist still envisaged that greater measure is required to combat the release of this harmful gases. This means that all cost-effective means of reducing carbo

Techno-Economic Assessment of Renewable Electricity for Rural Electrification and IT Applications in Selected Sites Across the Geopolitical Zones of Nigeria

This study presents an energy resource assessment for six sites, one from each geo-political zone of Nigeria. It assessed the feasibility and economic viability of RE resources that can provide sustainable electricity and enhance ICT development for rural communities cut off from the national grid. Hypothetical rural communities made up of 200 homes, a school and health centre was conceived. Specific electrical load profile was developed to suite the rural communities. The required load was analyzed as 358 kWh per day, with 46 kW primary peak load and 20 kW deferrable peak load. The meteorological data utilized were obtained from the Nigeria Meteorological Department spanning 1987- 2010. Assessment of the design that will optimally meet the daily load demand with LOLP of 0.01 was carried out by considering standalone PV, Wind and Diesel, and a hybrid design of Wind-PV. The Diesel Standalone system was taken as the basis for comparison. The optimization tool employed after the feasibility analysis with RETScreen® software was the HOMER® software. The outcome showed that the most economically viable alternative for power generation at most of the sites is the wind standalone system. It proved to be the optimal means of producing renewable electricity in terms of life cycle cost and levelised cost of energy which ranged between $0.129/kWh for Jos and$0.327/kWh for Benin City. This is very much competitive with grid electricity. Renewable technologies could then become the subject of rigorous pursuit for rural electrification and ICT development in local communities around the sites

Detection of antibody-dependent complement mediated inactivation of both autologous and heterologous virus in primary HIV-1 infection

Specific CD8 T-cell responses to human immunodeficiency virus type 1 (HIV-1) are induced in primary infection and make an important contribution to the control of early viral replication. The importance of neutralizing antibodies in containing primary viremia is questioned because they usually arise much later. Nevertheless antienvelope antibodies develop simultaneously with, or even before, peak viremia. We determined whether such antibodies might control viremia by complement-mediated inactivation (CMI). In each of seven patients studied, antibodies capable of CMI appeared at or shortly after the peak in viremia, concomitantly with detection of virus-specific T-cell responses. The CMI was effective on both autologous and heterologous HIV-1 isolates. Activation of the classical pathway and direct viral lysis were at least partly responsible. Since immunoglobulin G (IgG)-antibodies triggered the CMI, specific memory B cells could also be induced by vaccination. Thus, consideration should be given to vaccination strategies that induce IgG antibodies capable of CMI