Impact force of melon seeds during shelling

Melon seeds are shelled in a rotating impeller – a type of machine to obtain the cotyledons.  The seeds exit the impeller and impact a cylindrical ring shelling the seeds.  Because of the impact force, some of the seeds are broken, which would deteriorate in storage and make lower market value.  An analytical method was used to determine the factors affecting the impact force on the ring.  Experimental compression tests were carried out to determine the static force for breaking melon seeds.  Some seeds were also shelled with an experimental shelling machine and the number of broken seeds was counted. Analysis results showed that the factors affecting the impact force were impeller speed, seed cross-section area at impact and mass ratio.  The mean forces for breaking melon seeds were 13.14×10-3 N, 19.62×10-3 N and 19.55×10-3 N for orientations of breadthwise, lengthwise with tip up and lengthwise with tip down respectively.Keywords: impact force, melon seeds, shelling, analysis Citation: Okokon F. B., E. Ekpenyong, C. Nwaukwa, N. Akpan, and F. I. Abam.  Impact force of melon seeds during shelling.  Agric Eng Int: CIGR Journal, 2010, 12(1): 182-188.&nbsp

Thermoeconomic and thermoenvironomic modeling and analysis of selected gas turbine power plants in Nigeria

This study presents comprehensive thermoeconomic and thermoenvironomic modeling and analysis of selected gas turbine power plants in Nigeria using the first and second laws of thermodynamics (exergy) concept. Exergetic analysis was conducted using operating data obtained from the power plants to determine the exergy destruction and exergy efficiency of each major component of the gas turbine in each power plant. The results of the study showed that the combustion chamber (CC) is the most exergy destructive component compared to other cycle components. The percentage of exergy destruction in CC varies between 86.05% and 94.6%. By increasing the gas turbine inlet temperature (GTIT), the exergy destruction of this component can be reduced. The total exergy improvement potential of the selected plants varies from 54.04 to 159.88 MW. The component with the highest exergy improvement potential is the CC, which has the value that varies from 30.21 to 88.86 MW. Thermoeconomic analysis showed that the cost of exergy destruction is high in the CC, and an increase in the GTIT effectively decreases this cost. The exergy costing analysis revealed that the unit cost of electricity produced in the plants ranged from cents 1.99/kWh (N3.16/ kWh) to cents 5.65 /kWh (N8.98/kWh). Thermoenvironomic analysis showed that the CO2 emissions varied between 100.18 and 408.78 kg CO2/MWh, while cost rate of environmental impact varied from 40.18 $/h (6, 388.62 N/h) to 276.97$/h (44, 038. 23 N/h). The results further showed that CO2 emissions and cost of environmental impact decrease with increasing GTIT. The sustainability index increase with increasing GTIT. Finally, this study will assist efforts to understand the thermodynamic losses in the gas turbine cycle, and to improve efficiency as well as provide future recommendations for better performance, sustainability, and lessening environmental impact of power plant

Analysis of the influence of outdoor surface heat flux on the inlet water and the exhaust air temperature of the wetting pad of a direct evaporative cooling system

© 2023 Elsevier Ltd. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1016/j.applthermaleng.2023.120292The study investigates the interconnectivity between the inlet water temperature, wind flow rate, and storage water heat flux with the performance of biomass wetting pads in direct evaporative cooling under the external ambient condition of Sub-Saharan Africa. Thus, a standalone direct, evaporative cooling system with an upper water storage tank exposed to wind flow was locally developed and evaluated with jute, palm fruit mesocarp and wood charcoal as biomass cooling pad at three air velocities and constant pad thickness and three different air flow rates. The results indicated that increasing the heat flux around the water tank and decreasing the relative humidity of the inlet air through the wetting pad will lower both the inlet water and pad exhaust temperatures. The water demand was higher in palm fruit mesocarp fibre at airflow rates of 3 m/s, while at 4 and 4.5 m/s, it was higher in wood charcoal, and the value ranged from 9.64 × 10 −4 to 1.46 × 10 −3 kg/s. Except for jute fibre at 4 m/s, higher humidity difference or low cold room temperature did not translate to higher evaporative cooling effectiveness or efficiency. However, the lower inlet water temperature significantly affected the evaporative effectiveness. This shows the possibility of free moisture transfer into the cold room from the pad materials at increased air flow rates that helped boost the exhaust air's humidity. The average evaporative efficiency for the three pads ranged from 56.4 % to 80.96 %. The values for the enlargement coefficient ranged from 5 to 6.82, while the temperature thermal stress ranged from 24.37 to 28.66 °C.Peer reviewe