PC-based low-cost CNC automation of plasma profile cutting of pipes

James N. Keraita and Kyo-Hyoung Kim

In modern fabrication shops, it is important to invest in affordable, state-of-the-art technology; including material handling systems, computerized motion control, advanced cutting systems and dedicated software programs in order to compete effectively in the market. In pipe profile cutting operations using plasma arc, CNC automation introduces higher precision, repeatability and speed. One method of simplifying the automation and hence improving the profit margins is the reduction of the number of controlled axes. Further by simplifying the design, the CNC machine is made more compliant to the technique of error modeling and compensation. This research investigated the suitability of a PC-based CNC pipe cutting machine by simultaneous control of only two axes. The developed machine competes well with similar machines having higher number of axes. The shortcomings arising from such simplification of the machine and the plasma arc cutting (PAC) process in general; are pointed out and possible improvements suggested.

Effect of microbial growth on biogas generation using carrier material in the self circulating biogas plant

N. Stalin and H. J. Prabhu

A modified three stage methane fermentation system was developed to digest animal manure effectively. The digester having an effective volume of 200 liter is constructed with central tube filled with burnt bricks. The burnt brick in the central portion of the digester increase the microbial concentration by immobilizing the bacteria on the surface of the burnt brick. The size of brick materials is not more than 3 to 5 mm size. The carrier materials used in the digester are 5%, 10%, 15%, and 20% of the total volume of the digester and also for each percentage 3.5kg of cow dung and 3.5kg of water (1:1) is well mixed and added daily. The readings were taken between biogas generations versus time for each percentage continuously up to 90 days. It was observed that 10 to 15 percentage of carrier material from the total volume for microbial growth gave more gas generation. Operational temperature was from 30°C to 50°C. In this study we examined the effect of microbe growth, temperature on biogas generation and hydraulic retention time.

MHD unsteady free convective Walter’s memory flow with constant suction and heat sink

M.V Ramana Murthy, G. Noushima Humera, Rafiuddin and M. Chenna Krishan Reddy

The study of unsteady hydromagnetic free convective memory flow of incompressible and electrically conducting fluids past an infinite vertical porous plate in the presence of constant suction and heat absorbing sinks have been made. Approximate solutions have been derived for the mean velocity, mean temperature, mean skin-friction and mean rate of heat transfer using multi-parameter perturbation technique. It is observed that magnetic field strength decreases the mean velocity of the fluid. Also the mean skin-friction and mean rate of heat transfer of the conducting fluid decreases with the increase in magnetic field strength.

The targeting problem for S-type quality characteristics

K. Tahera, R. N. Ibrahim and P. B. Lochert

The targeting problem generally identifies the process parameters such as the initial process means of a production process. The joint determination of the initial process means and the production run has been reported in the literature. Most of these studies considered a process with multiple independent nominal-the-better type (N-Type) of quality characteristics. In a real industrial situation, the quality characteristics may depend on each other. In addition, the process could have other types of quality characteristics. In this paper, a mathematical model is developed that jointly determines the optimum initial process means and production run of a process with multiple dependent smaller-the-better type (S-Type) of quality characteristics. A Numerical example is also provided to demonstrate the application of the proposed model.

Transient mathematical model of both side single pass photovoltaic thermal air collector

Ebrahim M. Ali Alfegi, Kamaruzzaman Sopian, Mohd Yusof Hj Othman and Baharudin Bin Yatim

A mathematical model and solution procedure of a single pass photovoltaic thermal air collector (PVT) with Compound Parabolic Concentrator (CPC) and fins with both sides of the absorber for predicting the thermal and combined photovoltaic thermal performance of the system is presented. The air which is the working fluid flows between top glass and absorber plate and between absorber and bottom plates. The mathematical model is composed of five couple unsteady nonlinear partial equations which are solved by using Gear implicit numerical scheme. The temperatures of the circulated air as a function of distance in the flow direction for both sides are predicted. Results at solar irradiance of 400 W/m2 show that the combined pv/t efficiency is increasing from 26.6 % to 39.13 % at mass flow rates varies from 0.0316 to 0.09 kg/s.

Characterization and frequency analysis of one day annual maximum and two to five consecutive days’ maximum rainfall of Accra, Ghana

Xeflide Seth Kwaku and Ophori Duke

Abstract:

Annual one day maximum rainfall and two to five consecutive day’s maximum rainfall corresponding to a return period of 2 to 100 years has been conducted for Accra, Ghana. Three commonly used probability distributions; normal, lognormal and gamma distribution have been tested to determine the best fit probability distribution that describes the annual one day maximum and two to five consecutive days’ maximum rainfall series by comparing with the Chi-square value. The results revealed that the log-normal distribution was the best fit probability distribution for one day annual maximum as well as two to five consecutive days’ maximum rainfall for the region. Based on the best fit probability distribution a maximum of 84.05 mm in 1 day, 91.60 mm in 2 days, 100.40 mm in 3 days, 105.67 mm in 4 days and 109.47 mm in 5 days is expected to occur at Accra every two years. Similarly a maximum rainfall of 230.97 mm, 240.49, 272.77 mm, 292.07 mm and 296.54 mm is expected to occur in 1 day, 2, 3, 4 and 5 days respectively every 100 years. The results from the study could be used as a rough guide by engineers and hydrologists during the design and construction of drainage systems in the Accra metropolis as poor drainage has been identified as one of the major factors causing flooding in Accra.

Performance test of IC engine using Karanja biodiesel blending with diesel

N. Stalin and H. J. Prabhu

Biodiesel production is a modern and technological area for researchers due to constant increase in the prices of petroleum diesel and environmental advantages. This paper presents a review of the alternative technological methods that could be used to produce this fuel. Biodiesel from karanja oil was produced by alkali catalyzed transesterification process. Performance of IC engine using karanja biodiesel blending with diesel and with various blending ratios has been evaluated. The engine performance studies were conducted with a prony brake-diesel engine set up. Parameters like speed of engine, fuel consumption and torque were measured at different loads for pure diesel and various combinations of dual fuel. Brake power, brake specific fuel consumption and brake thermal efficiency were calculated. The test results indicate that the dual fuel combination of B40 can be used in the diesel engines without making any engine modifications. Also the cost of dual fuel (B40) can be considerably reduced than pure diesel.

Mixing time estimation and analysis in a jet mixer

P. Kalaichelvi, Y. Swarnalatha and T. Raja

Abstract:

Mixing of reactants, catalysts, etc. in a chemical reactor may be achieved using jets which offer the advantage of having no moving parts inside the reactor. While there have been many experimental studies and thumb rules for the design of jets, the details of mixing process is not properly understood. An experiment was carried out to study the effects of various parameters such as nozzle diameter, angle of inclination, jet position and jet velocity on mixing time. Results show that, for a given geometric arrangement, the angle of the jet injection is significantly more important in determining the time required for 95% mixing than the length of the jet. The optimum angle was found to be an injection angle of 30º for jet located either at two-third of the volume of the tank or top and bottom of the tank, which gave the shortest mixing time. The optimum angle is not universal and varies with the location of the jet inlet. An increase in the nozzle diameter was found to reduce the mixing time at a given level of power consumption and in turn the energy efficiency can be improved.

Effects of variable viscosity, heat and mass transfer on nonlinear mixed convection flow over a porous wedge with heat radiation in the presence of homogenous chemical reaction

R. Kandasamy, I. Hashim, Muhaimin and Ruhaila

Abstract:

An analysis is carried out to study the variable viscosity and chemical reaction effects on flow, heat and mass transfer characteristics in a viscous fluid over a porous wedge in the presence of heat radiation. The wall of the wedge is embedded in a uniform Darcian porous medium in order to allow for possible fluid wall suction or injection. The governing boundary layer equations are written into a dimensionless form by similarity transformations. The transformed coupled nonlinear ordinary differential equations are solved numerically by using the R. K. Gill and shooting methods. The effects of different parameters on the dimensionless velocity, temperature and concentration profiles are shown graphically. Comparisons with previously published works are performed and excellent agreement between the results is obtained. The results are presented graphically and the conclusion is drawn that the flow field and other quantities of physical interest are significantly influenced by these parameters.

Study on strength and sorptivity characteristics of fly ash concrete

Anurag Misra, Rohit Ramteke and Madan Lal Bairwa

Abstract:

When fly ash is added in concrete, the reactive silica present in fly ash reacts with calcium hydroxide liberated during cement hydration and forms calcium silicate hydrate (C-S-H) gel. Compact C-S-H gel gives higher strength and lower permeability and absorption characteristics. They are indicators of durability of concrete. Therefore, a study was carried out on influence of fly ash on sorptivity of OPC-Fly Ash concrete. The experiments were conducted using a mix proportion of cement (1) : sand (1.57) : 10 mm aggregates (1.35) : 20 mm aggregates (2.03) with four water to cementitious material (Cement + Fly Ash) ratios (w/cm) (0.55, 0.475, 0.40 and 0.340). The cement replacement by fly ash was varied between 0 to 50%. Compressive strength and water absorption tests were conducted on each of the twenty-four mixes. The sorptivity of concrete was compared with that of the control concrete. The results indicated that higher volume of cement replacement and lower w/cm ratios have lower values of cumulative water absorption and sorptivity. There was a small reduction in 28 days compressive strength of concrete with increase in fly ash content. However, it was found to be almost the same or marginally higher than that of control mix at 90 days.

Characterisation and optimisation of deferration of Kankara clay

J. A. Lori, A. O. Lawal and E. J. Ekanem

Abstract:

The mineralogy of clay from the Kankara deposit in Katsina (Nigeria) has been studied by x-ray diffraction (XRD). Kaolinite is the dominant mineral phase with minor amounts of quartz, goethite and muscovite. The diffraction pattern of the glycolated clay sample did not indicate the presence of mixed layer clay (swelling clay such as smectites). Iron impurities (FeOOH), alumina (Al₂O₃) and silica (SiO₂) contents of untreated and beneficiated clays were monitored by Energy Dispersive X-ray Fluorescence (EDXRF). The total iron impurity (FeOOH) in the clay sample was 0.081%. Alumina (Al₂O₃) and silica (SiO₂) contents were 39.097% and 44.158%, respectively. The iron content of the oxalic acid-leached clay decreased with increase in oxalic acid concentration. The efficiency of the acid solution was more, when the iron/acid mole ratio was less than or equal to 0.045. Iron removal efficiency of the oxalic acid solutions was not dependent on the amount of iron present in the clay, but on the mole proportion of the acid used. The optimum conditions for about 99% deferration were temperature of 75°C, oxalic acid concentration of 1.8mol/dm3 and shearing time of 7hrs. The use of magnetic separator showed no improvement on iron removal from the clay.