Development and performance evaluation of a natural draft mixed-type solar dryer for agricultural products

Reduced moisture content enhances storage properties of agricultural products and reduces post-harvest losses. Effective drying can be achieved using solar dryers in regions with abundant solar radiation. In this study, a natural draft mixed-type solar dryer suitable for rural communities of developing countries was developed. The performance of the solar dryer was also investigated using pepper, okra and tomato. The temperature taken at different points of the drying chamber and the auxiliary collector show that the temperature within the drying chamber is higher than the ambient temperature. The temperature within the drying chamber was also found to depend on the atmospheric conditions. The maximum drying rate was obtained at periods between 1200 and 1400 hrs Nigeria local time during which the temperature within the solar dryer is also maximum. Temperature within the solar dryer reached up to 62°C. The solar collector efficiency was 52.0% while the drying efficiency was 21.9%.Peer reviewe

Rheological characteristics of aluminium oxide (AL2O3) based nanolubricant

This paper presents the rheological measurement of aluminium oxide (Al2O3) nanolubricant. The nanolubricant was prepared using the two-step method from dry Al2O3 nanoparticles and Capella D lubricant as base fluid. The dynamic viscosity of the Al2O3 nanolubricant at constant shear rate was measured at atmospheric pressure in the temperature range of 278 K to 323 K for pure based lubricant along with nanolubricant mass concentration of 1%, 2% and 4% with nanoparticle size of 10 nm, 20-30 nm and 80 nm. The measured data was analysed using the linear fit and exponential function fit. The result showed that at constant particle size and concentration, the dynamic viscosity reduces with increase in temperature while at constant temperature, the viscosity increased with nanoparticle concentration. The exponential function fit regression best describe the relationship between the viscosity and temperature when compared with the linear fit regression while the polynomial function fit best describe the relationship between the viscosity and mass concentration. Keywords: Dynamic viscosity, nanolubricant, shear rate, regression, concentration, temperatur

Modeling and simulation of the effect of moisture content and ambient temperature on gas turbine power plant performance in Ughelli, Nigeria

The influence of ambient temperature and moisture content on the performance of Transcorp Power Plant, Ughelli, Delta State, Nigeria was investigated with the aid of a digital psychrometer. The simulation was done using codes developed on MATLAB R2017a and the results show that compressor power consumption increased by 1.65% for 0.7% rise in temperature, and 0.50% for 71.4% rise in moisture content. The specific fuel consumption also increased with increase in temperature where a 1.71% rise in ambient temperature resulted in a 0.15% rise in specific fuel consumption but it decreased by 0.49% for a 41.7% rise in moisture content. A 1.62% rise in temperature led to a 0.13% drop in net power output and a 29.4% rise in moisture content resulted in a 0.48% drop in net power output. Thus gas turbine plant operates optimally in areas with low ambient temperatures and high moisture content. Keywords: Work ratio, net power, efficiency, moisture content, specific fuel consumption, heat rate

Experimental Investigation of Cutting Parameters on a Turning Tool Flank Wear (Industrial and Production Engineering)

Tool life has been a major source of concern to manufacturers, the extent of usefulness of any tool depends on it. The major cause of tool failure is tool wear and the most important aspect of wear to a machinist is the flank wear as it is the flank that is in direct contact with the work piece. This research investigates various cutting parameters and how they contribute to tool wear. The model used is the new wear model proposed by Palmai. The research involved the experimental investigation of turning on the Sumore SP 2110 lathe machine using ISOP Tungsten Carbide and High Speed Steel (HSS) as tools and Bright Mild Steel and Stainless Steel as work piece. The experimental data were used to calibrate the Palmai model for the various cutting tool and work piece pair, at different cutting parameters of spindle speeds depth of cut and feed rate. Experimental and Paimai wear results show good correlation, with about 1.5% to 5.4% deviation

FSA Direct Farm Loan Program Graduation Rates and Reasons for Exiting

Farm Service Agency (FSA) direct loans are intended to provide transitory credit to creditworthy borrowers unable to obtain conventional credit at reasonable terms. Farm loan program (FLP) effectiveness is measured in part by how readily direct loan borrowers graduate to conventional credit. A survey of FSA borrowers originating direct loans during fiscal years 1994-1996 is utilized to estimate graduation rates. A majority of 1994-1996 loan originators did exit the direct FLP by November 2004. A multinomial logit model indicates financial strength at origination resulted in greater likelihood of farming without direct loans approximately nine years after loan origination.Agricultural Finance,

Analysis of Farm Service Agency Direct Loan Loss Likelihoods and Loss Rates

The USDA's Farm Service Agency (FSA) serves as the nation's lender of last resort by providing direct loans to farmers unable to obtain credit at reasonable rates and terms. Annual loan losses have been substantial, averaging $576 million for fiscal 1994-2004. An econometric model using survey data from a sample of FSA loans originated in fiscal 1994-1996 is estimated to identify factors associated with loan losses. The results indicate previous debt settlement experience, loan type, farm type, farm size, and farm financial characteristics are important factors. This information may be used by FSA to adjust its underwriting standards in an effort to reduce loan losses and provide additional loans to farmers given its current funding.Agricultural Finance,

Experimental Investigation and FE Simulation of the Effect of Variable Control on Temperature Distribution in Orthogonal Metal Cutting Process

The study aimed at building a 3-Dimensional finite element simulation to monitor orthogonal machining process under a dry machining environment. The study was conducted in two stages of experimentation and finite element modelling and simulation (FEMS). The purpose of the experimentation was to obtain data which will be used to validate the FEMS result. The FEMS was carried out with a commercially available solver. The workpiece material employed for the study was mild steel in the form of round bar of solid shaft having 45 mm diameter and length of 500 mm. Mild steel was selected due to its wide range of applications in the fields of manufacturing tools and mould industry. The tool material used was tungsten carbide of DIN4980R 20 mm x 20 mm, with cutting angle of 80-degree tool steel, which was modelled in the FEMS as a rigid body. Various cutting conditions such as speed, feed rate and depth of cut were considered to obtain the tool chip temperature. Different values of temperature were recorded at interval of 10 seconds and ranged from 10 to 100 seconds. The FEMS was carried out by making one of the conditions vary while the others were constant. The temperature values measured with a digital thermocouple were used to validate the FEMS data obtained. The result show that the cutting temperature predicted by the FEMS is within 20% of the real experimental value and followed the same trend. It was discovered that the values of temperature obtained from simulation were also much higher than that of experimentation. Therefore, the experimental value might not be accurate, due to some experimental errors and environmental effects like partial contact between the measuring device and the cutting tools, fluctuation in the magnitude of air flow around the surrounding which may affect the cutting temperature, room temperature and pressure effect. Generally, with an increase in the cutting speed, feed rate and depth of cut, the tool temperature also increased and the cutting speed was found to be the most effective parameter when consideration is given to temperature effects, especially in high range of cutting conditions

Development of Thermomechanical Model for the Analysis of Effects of Friction and Cutting Speed on Temperature Distribution around AISI 316L During Orthogonal Machining

In metal cutting,severe deformation takes place in the vicinity of the cutting edge of the high strain-rate and an increase in temperature is observed. Deformation behaviour of the work material in the primary and secondary zones is highly sensitive to the cutting conditions. Also, the frictional conditions between the tool and the chip and tool and the workpiece are highly complex and sensitive to the cutting conditions. As a result, the stresses and temperatures at tool-chip interface and around the cutting edge can be critically high in some cutting conditions and can cause excessive tool wear or premature tool failure. This research work focuses on the accurate prediction of the distribution of the process variables such as stresses and temperatures with the Finite Element (FE) Analysis to identify optimum cutting conditions, tool material, edge geometry and coating in order to help improve productivity and quality of machining operations. Effects of work material flow stress and interfacial friction at chip-tool interface on the accuracy of the predicated process variables in FE simulations are also analyzed. Specifically, friction models and cutting speed are varied to predict the effect on the temperature distribution, stresses and strain on the workpiece and tool chip during orthogonal cutting process. The result showed that an increase in coefficient of friction will cause an increase in thermal, force and mechanical variables during machining. Thus, the higher the coefficient of friction, the higher, the cutting forces, temperature, stress, and strain

Modelling and Control of Flow Induced Vibration of Top–Tensioned Marine Risers Using Analytical Methods

For a riser array in deep waters, interference between individual risers in strong ocean current is of operational concern and thereby a key design issue. The lateral deflection is likely to be large, and the risers may experience collision with fatigue or coating damage as a consequence. In this paper, active control of flexible marine riser angle and the reduction of flow induced (forced) vibration under a time varying distributed load were considered using boundary control approach. A torque actuator was introduced in the upper riser package and a boundary control was designed to generate the required signal for riser angle control and vibration reduction with guaranteed closed-loop stability. The design is based on the partial differential equations of the system, which are developed using energy principle. Analytical method of solution was deployed with the aid of a program, developed within the framework of MATLAB, to predict the riser's behaviour by top tensioning. A sensitivity analysis for different values of the control variables was carried out. The results of this work showed that active control of flexible marine riser by top-tensioning reduced flow induced vibration