Coal combustion models: a review

Abstract : Computational Fluid Dynamics has been used for optimisation of industrial applications with some level of success. The modest accuracy provided by some of the combustion models in use has left some room for research and improvement. Coal is presented as a fuel with complex chemical properties due to its fossil fuel nature. The devolatilization process of coal is investigated with special attention to the best models that can handle heavy and light volatiles found in coal. The heterogenous char combustion is also presented paying attention to the nature of the char particle during the combustion process. The other processes such as drying, homogenous volatile combustion, radiation models, particle tracking models and turbulent models are investigated in a general manner as they rarely vary with the type of fuel being investigated. A summary of the industrial applications that have successfully utilised the CFD models for optimisation of coal combustion are presented thus helping in drawing the final conclusion

Performance evaluation of a plate encapsulated salt hydrate PCM mixed with a gel

Abstract : An alternative method of cooling is required to meet cooling demands and simultaneously decrease conventional energy consumption. The current research aimed to investigate the feasibility of using a phase change material (PCM) in the form of a salt hydrate mixed with a CSIR-developed gel for PCM based cold storage that used nighttime cold to cool ambient air during the day. The experiments were conducted over a time period of three hours between 12:00 pm and 15:00 pm in the afternoon. The total temperature drops were found to be 3.8, 2.9 and 2.6 degrees for air flow rates of 0.03, 0.05 and 0.06kg/s respectively. The total energy transferred for each of the mass flow rates averaged 140.9, 144.4 and 158.9J for air flow rates of 0.03, 0.05 and 0.06kg/s respectively

Investigation of household refrigerator system with varied capillary tube length

Abstract : In this paper, the performance of R600a was investigated in a household refrigerator originally designed to work with R134a using varied capillary tube length (1.0, 1.15, 1.30 and 1.45 m). The refrigerator was instrumented with four thermocouples at the inlet and outlet of the major components. Also, two pressure gauges were connected to the compressor to measure the suction and discharge of the compressor. The experimental results were used to evaluate the performance of the system. The results showed that at optimal capillary tube length the COP and cooling capacity of R600a in the system increased with 45% and 4.2% respectively and the power consumption reduced with 25% using 1.30 m varied capillary tube length compared to R134a. Conclusively, R600a can serve as a retrofit in the household refrigerator systems originally designed to work with R134a refrigerant

ASSESSMENT OF CHEMICAL AND ANTINUTRITIONAL PROPERTIES OF BREAKFAST MEAL PREPARED FROM BLENDS OF BANANA AND AFRICAN YAM BEAN

Banana (Musa sapientus) and African yam bean (Sphenostylis stenocarpa) are nutritional food sources that are valuable industrially even in consideration for a balanced nutrition. This research work evaluates the production of breakfast meal from blends of Banana and African yam bean (AYB). Banana and AYB were mixed in the ratio 90:10, 80:20, 70:30 and 100:0 (control) for the production of breakfast meal. Crude protein, ash, crude fiber, fat and carbohydrate content of mixtures were determined using the AOAC methods. Vitamins, minerals and anti-nutrient composition of the breakfast meal were determined using standard methods and data were analyzed using Analysis of Variance (ANOVA). Sensory attributes were determined using 9-point hedonic scale by forty panelists. The results of the proximate analysis showed that protein ranged from 5.41-11.26%, fat content (1.97-4.56%), carbohydrate (72.71-79.89%), fiber (0.39-0.57%), ash (3.23-3.97%) and moisture content (7.86-8.20%). Oxalate (8.73-4.38%) decreased with increase in AYB inclusion. Tannin values ranged from 17.09-26.73% and phytate ranged from 11.59-46.77%. The sensory evaluation by the panelists shows that the product was widely accepted. Samples 100:0 and 90:10 were mostly preferred in terms of colour, texture, taste, crispiness, sweetness, flavour, appearance and general acceptability. Hence, the fortification of banana flakes with AYB can be encouraged as a breakfast meal

Dataset and ANN model prediction of performance of graphene nanolubricant with R600a in domestic refrigerator system

Abstract: This work evaluated the steady state performance of R600a in the base lubricant and graphene nanolubricant. The mea- suring instruments required and their uncertainties were provided, step by step method and procedures for prepara- tion of graphene nanolubricant concentration and substitut- ing it with the base lubricant in domestic refrigerator system are described. The system temperatures data was captured at the inlet and outlet of the system components. Also, the pressures data was recorded at the compressor inlet and out- let. The data was recorded for 3 h at 30 min interval at an ambient temperature of 27 °C. The experimental dataset, Ar- tificial Neural Network (ANN) training and testing dataset are provided. The artificial intelligence approach of ANN model to predict the performance of graphene nanolubricant in do- mestic refrigerator is explained. Also, the ANN model pre- diction statistical performance metrics such as Root Mean Square Error (RMSE) and Mean Absolute Deviation (MAD), Mean Absolute Percentage Error (MAPE) and coefficient of determination (R 2 ) are also provided. The data is useful to researchers in the field of refrigeration and energy efficiency materials, for replacing nanolubricant with the base lubricant

Effect of Capillary Tube Length and Refrigerant Charge on the Performance of Domestic Refrigerator with R12 and R600a

In this work, the thermodynamic performance of a domestic refrigerator was experimentally studied by simultaneously varying the refrigerant charge (mr) and the capillary tube length (L). The potential of replacing R12 by R600a was also investigated. The test rig for the experiment was a vapor compression refrigerator designed to work with R12. The enthalpy of the refrigerants R600a and R12 for each data set for the experimental conditions were obtained by using REFPROP software (version 9.0). The results show that the design temperature of -120C (according to ISO - 8187 standard) and pull – down time of 135 minutes are achieved by using 60g of R600a with L= 1.2m and 1.5m. For R12, the design temperature is achieved at pull – down time of 165 minutes with mr = 40g and L = 0.9m. The appropriate combination of L and mr for R600a to be used as a drop-in refrigerant for R12 is found to be 1.5m and 60g on the basis of power consumption per day, pull-down time and COP, whereas by considering the cooling capacity, it is 0.9 m and 60g. The cooling capacity of R600a was about 9.18% higher than that of R12, the power consumed by R600a was about 24 % lower than that of R12 and the COP of R600a was about 6.3% higher than that of R12. In conclusion, the proposed R600a seems to be an appropriate long-term candidate to replace R-12 in the existing refrigerator in terms of power consumption, cooling capacity and COP

Preservation of Smoked African Catfish, Clarias gariepinus Burchell against Dermestes maculatus De Geer (Coleoptera: Dermestidae) using Neem Seed Oil-iodized Salt Mixtures

Dermestes maculatus is a major fish pest causing serious damage when left uncontrolled. This work identifies the fatty acids of Nigeria-obtained neem seed oil (NSO) and the potential of different mixtures of the NSO and iodized salt in the control of the pest. Seven fatty acids: palmitic acid (18.09%), linoleic acid (33.73%), stearic acid (14.37%), oleic acid (13.4%), octadecanoic acid (12.93%), 9, 12–octadecadienoic acid (1.47%) and arachidic acid (3.33%) were identified in the NSO. Percentage of D. maculatus adu1t mortality (100%) observed in fish treated with 0.00 μl NSO + 0.50 mg salt, 100 μl NSO + 0.125 mg salt and 0.00 μl NSO + 0.25 mg salt was significantly (p<0.05) different from mortality observed in untreated fish (31.25%). Percentage of live larvae (0.0%) in fish treated with 0.50 mg salt + 0.00 μl NSO, 100 μl NSO + 0.125 mg salt, 0.00 μ1 NSO + 0.25 mg salt and 50 μl NSO + 0.125 mg salt was lower than 63.97% observed in the control. Percentage of weight loss of untreated (75.10%) and 50 μl NSO-treated fish (69.65%) was significantly higher than values obtained from fish treated with 0.5 mg salt (26.93%), 100 μ1 NSO + 0.125 mg salt (25.73%) and 0.25 mg salt (23.63%). Application of NSO-iodized salt did not change the colour and odour of treated fish. Consumers significantly rejected fish treated with ≥ 50 μl NSO

Design and methods for a quasi-experimental pilot study to evaluate the impact of dual active ingredient insecticide-treated nets on malaria burden in five regions in sub-Saharan Africa

Background Vector control tools have contributed significantly to a reduction in malaria burden since 2000, primarily through insecticidal-treated bed nets (ITNs) and indoor residual spraying. In the face of increasing insecticide resistance in key malaria vector species, global progress in malaria control has stalled. Innovative tools, such as dual active ingredient (dual-AI) ITNs that are effective at killing insecticide-resistant mosquitoes have recently been introduced. However, large-scale uptake has been slow for several reasons, including higher costs and limited evidence on their incremental effectiveness and cost-effectiveness. The present report describes the design of several observational studies aimed to determine the effectiveness and cost-effectiveness of dual-AI ITNs, compared to standard pyrethroid-only ITNs, at reducing malaria transmission across a variety of transmission settings. Methods Observational pilot studies are ongoing in Burkina Faso, Mozambique, Nigeria, and Rwanda, leveraging dual-AI ITN rollouts nested within the 2019 and 2020 mass distribution campaigns in each country. Enhanced surveillance occurring in select study districts include annual cross-sectional surveys during peak transmission seasons, monthly entomological surveillance, passive case detection using routine health facility surveillance systems, and studies on human behaviour and ITN use patterns. Data will compare changes in malaria transmission and disease burden in districts receiving dual-AI ITNs to similar districts receiving standard pyrethroid-only ITNs over three years. The costs of net distribution will be calculated using the provider perspective including financial and economic costs, and a cost-effectiveness analysis will assess incremental cost-effectiveness ratios for Interceptor® G2, Royal Guard®, and piperonyl butoxide ITNs in comparison to standard pyrethroid-only ITNs, based on incidence rate ratios calculated from routine data. Conclusions Evidence of the effectiveness and cost-effectiveness of the dual-AI ITNs from these pilot studies will complement evidence from two contemporary cluster randomized control trials, one in Benin and one in Tanzania, to provide key information to malaria control programmes, policymakers, and donors to help guide decision-making and planning for local malaria control and elimination strategies. Understanding the breadth of contexts where these dual-AI ITNs are most effective and collecting robust information on factors influencing comparative effectiveness could improve uptake and availability and help maximize their impact