Research Articles

Permanent URI for this collectionhttps://atuspace.atu.edu.gh/handle/123456789/41

Browse

Now showing 1 - 20 of 36

Assessing the Performance of Liquid Waste Disposal Systems in West Africa: A Case Study in Ghana and Nigeria.
(Engineering Proceedings, 2022) Omani, J.; Acakpovi, A.
This research is an assessment of existing liquid waste disposal systems in West Africa and their performances over the years, using systems in Ghana and Nigeria as a case study. The main purpose of the study was to improve upon the sustainability of the systems, which according to earlier research activities, have been failing and resulting in health hazards. Ghana and Nigeria were selected because, from occurrences, especially in the West African sub-region, the two countries dictate the pace in contributions to the body of knowledge. Many portable liquid waste disposal systems were identified as part of the research process, as earlier researchers called for a paradigm shift from the practice of Europeanized systems that had not been successful in the entire sub-region. Many reasons have been attributed to the failures, and more worryingly, the systems continue to be operational despite their states of malfunctioning. Frequent power cuts and ineffective revenue generation contribute to numerous problems. West Africans have been enduring these occurrences for a long time with no solution in place. In a few instances, raw sewage is piped into a central biogas system for the future generation of electrical power; this system was found to be right on point because it was determined from the initial stages of development that by-products could be used to mitigate the high costs of maintenance. Another system that combines a biofil digester with its treated wastewater being channeled into a saturation pond was found to be a success because the outflow from the biofil was not meant to be channeled into main drains, as it did not wholly meet EPA approvals. The centralized sewage treatment systems have been functioning well in advanced countries; however, they are found to be ineffective in developing countries. The reasons included lack of availability for spare parts and coagulants, etc., which were normally imported. Additionally, when a larger community is targeted, revenue generation becomes a problem, thereby affecting return on investments (ROI) and operating and maintenance (O&M). None of the available central sewerage systems harvest by-products, making revenue generation a difficult task. The portable systems have been discussed in this research study, with examples and a record of performance over the years that could contribute to the body of knowledge in the field of sustainability for sewage treatment processes suitable for West Africa and for the whole of sub-Saharan Africa.
The characteristics of pure heterogeneous reaction for H2/Air mixture in the micro-combustors with different thermophysical properties.
(Applied Thermal Engineering, 2018) Zhang, Y.; Pan, J.; Lu, Z.; Tang, A.; Zhu, Y.; Bani, S.
This paper investigated the characteristics of pure heterogeneous reaction for H2/Air mixture under different wall thermophysical conditions namely; thermal conductivity, convective heat transfer and thermal capacity. The phenomena of pure heterogeneous reaction were observed by OH Planar Laser induced Fluorescence (OH-PLIF) to determine the working conditions. (3D)-models were built to numerically study the effects of different wall thermophysical conditions. The results show that lower thermal conductivity and convective heat transfer coefficient is beneficial to enhancing heterogeneous reaction and improve conversion rate of H2 as less heat is dissipated. The greater thermal capacity has beneficial impact on the reaction stability when the boundary condition changes, but no effect under the steady state. The performance of thermal conduction and convection were comprehensively considered to study the influence and proportion of each on the heterogeneous reaction. Higher thermal resistance can improve the reaction efficiency, reaction stability and reduce application cost. The influence of thermal conduction is greater than that of convective heat transfer.
Combined effect of injection timing and injection angle on mixture formation and combustion process in a direct injection (DI) natural gas rotary engine
(Energy, 2017) Fan, B.; Pan, J.; Yang, W.; Pan, Z.; Bani, S.; Chen, W.; He, R.
The application of direct injection (DI) technology is considered as a key solution to the problems of combustion efficiency and emissions on the rotary engine. This work aimed to numerically study the combined effect of injection timing (IT) and injection angle (IA) on mixture formation and combustion process in the 3D flow field of a DI natural gas rotary engine. On the basis of the 3D dynamic simulation model which was established in our previous work [29, 30], some critical information was obtained which was difficult to acquire through experiment. Simulation results showed that to satisfy the ideal fuel distribution for high combustion rate, a small IA should be used when the IT was at the early stages of intake stroke, and a big IA should be used when the IT was at the early stages of compression stroke. However, when the IT was at the middle and later stages of intake stroke, the IA which could satisfy the ideal fuel distribution, was difficult to determine with the changed IT in the middle and later stage of intake stroke. For the above reason, the middle and late stage of intake stroke was not recommended as injection timing in engineering application.
A comparative study of antibacterial activity of CuO/Ag and ZnO/Ag nanocomposites.
(Advances in Materials Science and Engineering, 2020) Asamoah, R. B.; Annan, E.; Mensah, B.; Nbelayim, P.; Apalangya, V.; Onwona-Agyeman, B.; Yaya, A.
The synergistic effects of transition metal based nanocomposites are known to possess enhanced antibacterial activities. However, in-depth analysis of the relative antibacterial performance of some of the prominent nanocomposites remains unavailable. This study compares the antibacterial activity of two separate nanocomposites, which are copper oxide with silver (CuO/Ag) and zinc oxide with silver (ZnO/Ag). The individual CuO/Ag and ZnO/Ag nanocomposites were synthesised by a mixed wet-chemical method. The resulting particles were analysed by XRD, XRF, TEM, UV-Vis spectrophotometer, BET, and FTIR. The antibacterial activity of the nanoparticles were tested on Gram-negative and Gram-positive bacteria, Escherichia coli (ATCC25922) and Staphylococcus aureus (ATCC25923), respectively, using the Kirby–Bauer disc diffusion and the microdilution methods. The Kirby–Bauer disc diffusion test results had the same minimum inhibition concentration (MIC) value for both CuO/Ag and ZnO/Ag against E. coli and S. aureus, which was 0.25 mg/ml. The applied nanocomposites using microdilution showed that CuO/Ag had approximately 98.8% and 98.7% efficiency on the respective Gram-positive and Gram-negative bacterial species, while ZnO/Ag achieved 91.7% and 89.3% efficiency, respectively, against the Gram-positive and Gram-negative bacterial species. This study presents a novel approach for relative analysis of the performance efficiency of transition metal based nanocomposites.
Convolutional neural networks for solid waste segregation and prospects of waste-to-energy in ghana
(IEOM Society, 2020) Abubakar, R.; Kumar, K. M. S.; Acakpovi, A.; Ayinga, U. W.; Prempeh, N. A.; Tetteh, J.; Kumassah, E. S.
Waste management and practices is a pervasive world problem. This is mainly due to the continuous rise in urbanization which comes along with a rise in waste generation. Even though proper waste management has a vital role to play in the ecological environment by greening through the recovery of energy from waste, its management is a menace. Reports in Ghana indicate that about 5 million tons of Municipal Solid Waste (MSW) is generated annually and about 60% is organic. Out of this, the non-recyclable components constitutes about 20%, which indicates that 80% can be recovered and recycled, technically. Further, about 25% of the organic waste received at the material recovery and compost facility remains as compost for use in agricultural and other purposes. Considering the population of Ghana pegged at 30 million in 2019, and daily solid waste production of about 0.45 kg per person (Amoah, 2006). Proper management and greening of MSW is very much essential with increasing demand of energy and that is what this paper seeks to tackle. This paper mainly emphases on analyzing and classifying (segregating) solid waste using Convolutional Neural Networks (CNN) to productively process solid waste materials to enhance the separation process of converting waste to energy. Also, the potentials and prospects of organic waste to energy is exploited to reveal the technologies, socio-economic benefits as well as the challenges of implementing waste to energy plants in Ghana. Raspberry Pi Board, a camera, LEDs, an LCD screen and a buzzer are major components used. Results indicate that, the system can effectively segregate solid waste that is recyclable and can be converted to energy. Feasibility studies of waste to energy also indicates that, combustion and anaerobic process of conversion ia mostly applied in Ghana, which has improved the greening and advocacy for clean environment. Again, the prospects of waste to energy was analysed using SmartPLS 3.0 and results indicate that, jobs, socio-economic, tourism, environmental cleanliness and reduction of communicable diseases are the benefits of installation of waste to energy plants in Ghana.
Development and characterization of clay–nanocomposites for water purification.
(Materials, 2020) Asamoah, R. B.; Yaya, A.; Nbelayim, P.; Annan, E.; Onwona-Agyeman, B.
In this work we propose a facile method of preparing cost-effective clay-metaloxide/metal (CuO/Ag and ZnO/Ag) composite pellets for an efficient water purification technique. Clay, with intrinsic antibacterial activity, served as a membrane support for different metaloxide/Ag nanoparticles (NPs) concentrations (2.5, 5 and 10 wt.%), as the active fillers. The effect of time (24 and 48 h) on the bactericidal activity of these pellets was also monitored. The clay–nanocomposite pellets were characterized using: X-ray diffraction, X-ray fluorescence, scanning electron microscopy, transmission electron microscopy, ultraviolet–visible (UV–Vis) spectrophotometry and nitrogen desorption analysis. The antibacterial activity performance was tested using E. coli and S. aureus strains of ATCC25922 and ATCC25923, respectively, in two aqueous media (nutrient broth and nutrient-free) by the colony-forming unit method. The results showed that the clay-CuO/Ag composite with a bandgap (1.24 eV) exhibited overall best performance under all conditions and time factors of ~100% efficiency in nutrient-free medium for all concentrations and times and 20–40% efficiency in nutrient broth for 24 h. The clay-ZnO/Ag with a bandgap of 2.88 eV showed no bactericidal activity in both media, except for that with 10 wt.% ZnO/Ag which showed 100% efficiency in nutrient-free medium after 24 h. All the synthesized composites showed 100% bactericidal efficiency in nutrient free medium after 48 h. These results indicate that, the clay/metaloxide/Ag could serve as efficient water purification technique, with a potential for large-scale commercialization.
The effect of embedded high thermal conductivity material on combustion performance of catalytic micro combustor.
(Energy Conversion and Management, 2018) Zhang, Y.; Pan, J.; Zhu, Y.; Bani, S.; Lu, Q.; Zhu, J.; Ren, H.
A novel micro combustor embedded with high thermal conductivity material has been proposed for micro-thermophotovoltaic system application. The effect of the materials, which is graphite and nickel with widths 1 mm and 3 mm on the thermal and radiant performance of the new micro combustor, was experimentally and numerically investigated. It was found that high and uniform temperature distribution along the walls of the combustor was obtained by embedding graphite with width of 1 mm because of the enhanced heat transfer, which is desirable for the micro-thermophotovoltaic system. The available radiation energy increased from 4.6 W for the conventional combustor to 5.2 W for the novel combustor when the inlet velocity was 1.0 m/s and the hydrogen/oxygen equivalence ratio was 0.5 under the experimental conditions. The available radiation efficiency increased from 8.9% to 9.8% and the effect of the embedded material could be enhanced by increasing the chemical energy input. Based on the combustor and fuel in this study, the conditions for good thermal performance are graphite with width of 1 mm, inlet velocity of 1.0 m/s and 0.5 equivalence ratio of hydrogen/oxygen by considering the reliability and durability of the combustor.
Effects of inlet parameters on combustion characteristics of premixed CH4/Air in micro channels.
(Journal of the Energy Institute, 2019) Zhang, Y.; Pan, J.; Tang, A.; Lu, Q.; Zha, Z.; & Bani, S.
In order to improve the stability of combustion and the working performance of the micro-combustor, this paper focuses on the effects of inlet parameters such as inlet temperature, mass flow rate and equivalence ratio. Three micro-combustors with different channel-heights are fabricated, and the three-dimensional calculation model is built to research on the combustion characteristics of premixed CH4/Air mixture. It was found that with inlet gas mixture temperature increasing, the flammability limits of the combustion under micro-scale conditions were expanded, and the channel height under which the flame can exist in the combustor reduced from 3.0 mm to 2.0 mm after preheating. On the preheating basis, increasing the equivalence ratio of the gas mixture Ф improved the intensity of gas-phase reaction due to the simulation of the important free radical like OH. Furthermore, when the inlet mass flow rate of methane mch4•was increased and between m1ch4•and m5ch4•, it shows that the external wall temperature was higher in the micro-combustor of H = 2.5 mm compared with that of H = 3.0 mm. When in the micro-combustor of H = 3.0 mm, more fuel could be burned and mmaxch4• = 2.85 × 10⁻⁶ kg/s.
Electronic properties of bulk and single-layer mos2 using ab initio dft: Application of spin-orbit coupling (soc) parameters
(Karazin Kharkiv National University, 2020) Gyan, M.; Botchway, F. E; Parbey, J.
Two dimensional (2D) materials are currently gaining a lot of interest due to excellent properties that are different from their bulk structures. Single and few-layered of Transition metal dichalcogenides (TMDCs) have a bandgap that ranges between 1-2 eV, which is used for FET devices or any optoelectronic devices. Within TMDCs, a ton of consideration is focused on Molybdenum Disulfide (MoS2) because of its promising band gap-tuning and transition between direct to indirect bandgap properties relies upon its thickness. The density functional theory (DFT) calculations with different functionals and spin-orbit coupling (SOC) parameters were carried out to study the electronic properties of bulk and monolayer MoS2. The addition of SOC brought about a noteworthy change in the profile of the band energy, explicitly the splitting of the valence band maximum (VBM) into two sub-bands. The indirect bandgap in bulk MoS2 ranges from 1.17-1.71 eV and that of the monolayer bandgap was 1.6-1.71 eV. The calculated parameters were compared to the obtained experimental and theoretical results. The obtained density of states (DOS) can be used in explaining the nature of bandgap in both the bulk and monolayer MoS2. These electronic characteristics are important for applications in material devices and energy-saving applications.
Entrepreneurship and the Need for Sustainable new technologies in power generation
(Energy and Power Engineering, 2020) Bani, S.; Abbey, S.; Quaynor, N.; Essel, E. A.
The increase of micro and nano devices has led to the miniaturization and multi-functionalization of micro-mechanical, communication, imaging, sensing, chemical analytical and biomedical devices. The devices so mentioned above need power sources that are portable, have short charging time, longevity, high energy density and are environmentally friendly. Chemical batteries hitherto used to be the major power source for these devices but have a drawback of having low energy density. The energy density of the most improved lithium-ion battery was in the region of 0.2 kWh/kg. Micro-combustor is one of the most important components of the micro thermophotovoltaic (MTPV) conversion device. This work used numerical simulation to investigate the effect of Micro pin fin arrays on combustion. Using a micro combustor with micro pin-fin arrays inserted, it was observed the fins widened the region of combustion and extended the blow-off limit in the combustor. The fins exerted great influence on combustion as flow rate increased and thus improved the temperature distribution of the wall. The combustor with fins possessed higher heat flux in comparison with combustor without fins. There was combustion stability at inlet velocity of 4 m/s making the micro pin-fin array configuration ideal for MTPV application. The results obtained will be useful in designing a MTPV.
Experimental investigation on the combustion characteristics of premixed CH4/O2 flame in a micro plate channel.
(Energy Procedia, 2017) Zha, Z.; Pan, J.; Yang, W.; Lu, Q.; Bani, S.; Shao, X.
The combustion characteristics of premixed rich CH4/O2 in micro channel was investigated experimentally via the visual micro-scale combustion test bench. The flammability limits, flame behaviors, stability limits and flame propagation speed were researched by changing the combustor sizes and inlet flow rates. The results show that there are three flame behaviors observed in the experiment, respectively external flame at the exit, stable flame in the channel, flame with repetitive extinction and ignition (FREI). Stable combustion zone increases with the increase of CH4 inlet flow rate. But the stability of the flame at high velocity may not be increased when the inlet flow rate is increased. The flammability limit was greater when the channel height was larger. Meanwhile, the increasing height and the decreasing length of the channel were also beneficial to stability limits in the channel with a certain range of equivalence ratios of 1.25 - 1.80. This experimental study on the combustion characteristics of premixed rich CH4/O2 in micro planar channels provides support for micro combustion in the future.
Experimental study on premixed methane-air catalytic combustion in rectangular micro channel
(Applied Thermal Engineering,, 2017)
The catalytic combustion process of pre-mixed methane-air in a rectangular micro channel was studied experimentally. Infrared thermal imager and flue gas analyzer were used to measure the temperature distribution of the outer wall and main components of exhaust gas respectively. Flammability limits of premixed methane-air in catalytic and non-catalytic micro channel were obtained by changing flow rates of methane, and the effects of equivalence ratio, inlet velocity and channel height on combustion characteristics were analyzed. Results showed that the flammability limits improved significantly when platinum was added into the micro channel. The highest centerline temperature of the outer wall was obtained at an equivalent ratio of 0.9 at the same inlet velocity with or without catalyst in the micro channel. Addition of catalyst in the channel not only gave a uniform temperature distribution on the outer wall of the channel but also improved methane conversion. With the increase of inlet velocity, the centerline temperature of the outer wall increased and the highest points of the temperature shifted to downstream of the channel gradually. Combustion intensity in the channel increased with the increase of channel height at the same inlet velocity.
Forecast of impacts of climate change on hydropower potential of Ouémé River at the 2040’s horizon in Benin
(International Journal of Energy and Power Engineering, 2018) Nounangnonhou, T. C.; Fifatin, F. X. N.; Aza-Gnandji, R. M.; Acakpovi, A.; Sanya, E. A.
Water is the most essential element for hydropower energy production. However, it has been well established that climate change will negatively globally impact water resources and in Sub-Saharan Africa particularly. It is therefore important to take this into account when assessing the potential hydropower energy of rivers to avoid overestimating their production’s capacity. This article firstly deals with the impacts of climate change on the forecast of potential hydropower energy of the Ouémé River Basin by 2040 and secondly develops the best equations for its exploitation. The data collected on three representative sites of the Ouémé River Basin (Bétérou, Savè, Kétou) from 1989 to 2016 and those derived from simulation of its flows from 2017 to 2040 by the Rural Engineering model (GR2M), made it possible to determine, first the monthly mean flow and, with the classified flow rate method, then evaluate the associated operating times. Using the obtained two parameters (mean flow-rate, production’s time), the hydropower energy was estimated as well, for period of 1989 to 2016, as for that of 2017 to 2040, and this in each of the retained three sites. The results show that the exploitable nominal flow-rates by hydro-electrical equipment set that can be installed are respectively 50 m3/s at Bétérou, 90 m3/s at Savè and 145 m3/s at Kétou. These results showed Kétou as the best site capable of hosting the largest hydropower energy plant on the Ouémé river basin. In Bétérou and Savè, the two-machines option (respectively 25 m3/s and 45 m3/s) is the most profitable, in terms of potential hydropower energy and its production duration, whereas in Kétou, the three-machines option of 50 m3/s each is the best.
Grid connected hybrid solar and diesel generator set: A cost optimization with HOMER
(ASTES Publishers, 2017) Acakpovi, A.; Michael, M. B.; Majeed, I. B.
Extensive increases in electricity cost added to the numerous power outages encountered in developing countries has led to the deployment of hybrid energy supplies that mainly ensure continuity of power supply while attempting a reduction of electricity generation cost. This paper, specifically deals with the cost optimization of electricity generation from a grid connected hybrid solar and diesel generator. An electrical audit was first conducted on a selected building: the Electrical Block of Accra Technical University. The load estimate led to a total energy of 234 kWh for all electrical gadgets with the exception of the air-condition systems. The estimate was used to design the hybrid system with HOMER software that resulted in a total capacity of 115 kW and a levelized cost of electricity of 0.472 $/kWh taking into consideration no power outage in the year. Furthermore, the proposed hybrid system was made of a grid connected solar system that supplies the full load with the exception of the air-condition systems generation from a grid connected hybrid solar and diesel generator. An electrical audit was first conducted on a selected building: the Electrical Block of Accra Technical University. The load estimate led to a total energy of 234 kWh for all electrical gadgets with the exception of the air-condition systems. The estimate was used to design the hybrid system with HOMER software that resulted in a total capacity of 115 kW and a levelized cost of electricity of 0.472 $/kWh taking into consideration no power outage in the year. Furthermore, the proposed hybrid system was made of a grid connected solar system that supplies the full load with the exception of the air-condition systems while the National Grid is used to cover the rest. In situation of power outages, the Generator Set takes over the National grid while the solar is still connected to the Grid. This mechanism was simulated and the cost of electricity in absence of the grid was estimated at 1.496 $/kWh. A general cost of electricity taking into consideration 90% ON period of the grid against 10% Off period of the grid per year, was estimated to 0.574 $/kWh. Besides, the proposed system produced savings in emission of carbon dioxide, 26.42 kg/year, sulfur dioxide, 115 kg/year and Nitrogen oxides, 56 kg/year. Finally, the system yielded a very good payback period of 10.43 years with regard to a lifetime of 25 years.
Harmonics of CF and LED lamps-maximum penetration perspective on power quality in distribution systems.
(Jurnal Nasional Teknik Elektro, 2020) Effah, F. B.; Gasu, P.; Okyere, P.; Acakpovi, A.
Global energy saving efforts have led to replacement of incandescent lamps with energy-efficient ones like light-emitting diode (LED) and compact fluorescent lamps (CFLs). These lamps, being non-linear loads, have the potential of injecting harmonics into distribution networks. In this paper, harmonics injection of common CFL and LED lamps at a facility point of common coupling is investigated. To gain insight into large scale penetration effects on power quality, field measurement results of popular lamps used in Ghana were replicated in MATLAB/Simulink through simulation. The field results showed that LED lamps exhibit more harmonics compared to CFL lamps. Maximum possible loading on a 100-kVA, 11kV/0.433kV distribution transformer was found to be 24.02% for CFL, 27.14% for LED, and 40.91% for a mixture of the two lamps, respectively, in order not to violate IEEE 519-2014 standard. The influence of other common loads such as ceiling fans on the lamps’ harmonics were assessed in the field measurement. The use of ceiling fans with the lamps in the facility reduced the harmonics and improved the power factor of the facility. Since the lamps exist in residential and commercial facilities with other loads, more penetration of energy-saving lamps in the distribution system will have little influence on power quality.
HCBST: An efficient hybrid sampling technique for class imbalance problems.
(ACM Transactions on Knowledge Discovery from Data, 2021) Sowah, R. A.; Kuditchar, B.; Mills, G.; Acakpovi, A.; Twum, R.; Osei, G.; Agboyi, R.
Class imbalance problem is prevalent in many real-world domains. It has become an active area of research. In binary classification problems, imbalance learning refers to learning from a dataset with a high degree of skewness to the negative class. This phenomenon causes classification algorithms to perform woefully when predicting positive classes with new examples. Data resampling, which involves manipulating the training data before applying standard classification techniques, is among the most commonly used techniques to deal with the class imbalance problem. This article presents a new hybrid sampling technique that improves the overall performance of classification algorithms for solving the class imbalance problem significantly. The proposed method called the Hybrid Cluster-Based Undersampling Technique (HCBST) uses a combination of the cluster undersampling technique to under-sample the majority instances and an oversampling technique derived from Sigma Nearest Oversampling based on Convex Combination, to oversample the minority instances to solve the class imbalance problem with a high degree of accuracy and reliability. The performance of the proposed algorithm was tested using 11 datasets from the National Aeronautics and Space Administration Metric Data Program data repository and University of California Irvine Machine Learning data repository with varying degrees of imbalance. Results were compared with classification algorithms such as the K-nearest neighbours, support vector machines, decision tree, random forest, neural network, AdaBoost, naïve Bayes, and quadratic discriminant analysis. Tests results revealed that for the same datasets, the HCBST performed better with average performances of 0.73, 0.67, and 0.35 in terms of performance measures of area under curve, geometric mean, and Matthews Correlation Coefficient, respectively, across all the classifiers used for this study. The HCBST has the potential of improving the performance of the class imbalance problem, which by extension, will improve on the various applications that rely on the concept for a solution.
Hetero-/homogeneous combustion characteristics of premixed hydrogen-air mixture in a planar micro-reactor with catalyst segmentation
(Chemical Engineering Science, 2017) Pan, J.; Lu, Q.; Bani, S.; Tang, A.; Yang, W.; Shao, X.
Numerical simulation of stoichiometric hydrogen-air premixed flame in a platinum-coated micro channel was performed to investigate hetero-/homogeneous combustion characteristics. An elliptical two-dimensional (2D) Computational Fluid Dynamics (CFD) model with detailed reaction mechanisms for homogeneous (gas phase) and heterogeneous (catalytic) reactions was adopted. The hetero-/homogeneous reaction characteristics with different inlet flow velocities and flame speeds were used to evaluate the effect of heterogeneous reaction on homogeneous reaction in the combustor with 2 mm length of catalyst segmentation. The effect of heat generation of the heterogeneous reaction was also analyzed. The numerical results indicated that the highest temperature in the catalytic combustor was lower than that in the combustor without catalyst. In the presence of heterogeneous reaction, the species (OH) concentration near the catalytic surface decreased significantly due to the dominated heterogeneous reaction at that region. The homogeneous ignition distance increased with increasing inlet flow velocity. The heat transfer from the catalytic surface to the gaseous mixture in the catalytic zone exhibited a high intensity under the large flow velocity, and the preheated incoming flow improved the heterogeneous reaction to inhibit the homogeneous reaction. The decreased flame speed in the catalytic combustor further demonstrated that the homogeneous reaction was suppressed by the heterogeneous reaction.
Impact of energy efficiency and conservation programs on the national grid in some selected households in Ghana.
(Energy Efficiency, 2022) Acakpovi, A.; Botwe-Ohenewaa, G.; Sackey, D. M.
This study evaluates the effect of energy efficiency and conservation on the Ghana National Grid. The motivation of this research study derives from the overwhelming lack of energy efficiency and conservation practices by consumers in Ghana while the existing generation continues to deplete with the increasing population and their growing energy needs. A survey was conducted on existing generation plants to assess their capacities and average power contributed to the national grid over a 6-month period. Energy efficiency and conservation awareness questionnaires was also administered to selected consumers to test their knowledge in energy efficiency and conservation. An energy audit and demand management program was established and implemented for a set of households, which were later audited, after a 3-month period to ascertain improvements in their energy consumption pattern. The study revealed that the implementation of energy efficiency and conservation measures led to a maximal reduction of energy consumed by 5.14% which is highly significant and subsequently led to positive economic and environmental implications. The study also found out that most of the respondents are unaware of energy efficiency and conservation measures; they make abusive use of non-efficient electrical appliances and do not implement any energy efficiency and conservation measures. The study recommended the development of policies and strategies to conduct mass education, to ensure the implementation of energy efficiency and conservation measures, and also to encourage the use of energy-efficient appliances. Successful implementation of the proposed recommendations contribute significantly to meeting the energy challenge in developing countries and subsequently sustain business while alleviating poverty.
Industrial applications of clay materials from Ghana-A review.
(Oriental Journal of Chemistry, 2018) Asamoah, R. B.; Nyankson, E.; Annan, E.; Agyei-Tuffour, B.; Efavi, J. K.; Kan-Dapaah, K.; Yaya, A.
Clay minerals are phyllosilicate groups naturally found in soils in all parts of the world. They have proven to be among the most essential industrial minerals because of their unique physicochemical properties and versatile applications within a wide range of fields including ceramics, construction, and environmental remediation, biomedical as well as cosmetics. Clay minerals are also primary to the production of other materials such as composite for secondary applications. In Ghana, clay mineral deposits are commonly found in several areas including soil horizons as well as geothermal fields and volcanic deposits, and are formed under certain geological conditions. This review seeks to explore the geographical occurrence and discusses the current uses of various local clay materials in Ghana in order to highlight opportunities for the utilization of these materials for other applications
The influence of injection strategy on mixture formation and combustion process in a direct injection natural gas rotary engine.
(Applied Energy, 2017) Fan, B.; Pan, J.; Yang, W.; Chen, W.; Bani, S.
The application of direct injection (DI) technology is considered as an effective way to improve the performance of the rotary engine. This work seeks to numerically dissect the influence of injection strategy on mixture formation and combustion process in a DI natural gas rotary engine. A 3D dynamic simulation model established in our previous work was used to acquire some critical information which was difficult to obtain through experimental investigations. These were the flow field, the fuel distribution, the temperature field and some intermediate concentration fields in the combustion chamber. Simulation results showed that for mixture formation, the motion mechanism of the fuel varies with the injection position. The mass of fuel located at the back of the combustion chamber for injection nozzles A, B and C, was determined by the intensity of vortex I, the coupling function between the value of the impact angle and the intensity of vortex I, and the value of the impact angle respectively. In addition, with retarded injection timing, the accumulation area of fuel for all injection nozzle positions moved from the back to the front of the combustion chamber at ignition timing. For combustion process, the overall combustion rate for the injection strategy (case A4) whose nozzle was 50 mm apart along the engine major axis and whose injection timing was 360°CA (BTDC), was the fastest. Compared with the out-cylinder premixed gas-filling method (case premix method), the improved combustion rate of case A4 had a 29.7% increase in peak pressure, but also a certain increase in NO emissions.

Browse

Browsing Research Articles by Title