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Heat Balance Analysis in Cement Rotary Kiln
Shihab Ali Khalifa,
Doha Yahia Alsadig
Issue:
Volume 4, Issue 2, April 2019
Pages:
26-32
Received:
7 October 2018
Accepted:
3 December 2018
Published:
26 May 2019
Abstract: The purpose of this study is optimizing the air and fuel quantities at kiln considering design parameters of the cement plant by keeping adequate safety factors at each level of calculations to assure that neither production rate nor quality of the clinker vary. Analysis of Heat balance was used to determine the sources of heat loss from the kiln system. Based on the collected data, an energy balance is applied to the kiln system. The physical properties and equations can be found in Perry’s handbook. The reference enthalpy is considered to be zero at 0°C for the calculations. The kiln has a capacity of 1000 ton-clinker per day. It found that the major heat loss is Heat losses by the kiln exhaust gas (2.33%), hot air from the cooler stack (7.28%), Radiation from kiln surfaces (11.71%). Some possible ways to recover the heat losses are introduced and discussed and they are Electricity generation, Heat recovery from kiln surface and Pre-heating raw material before the clinkering process.
Abstract: The purpose of this study is optimizing the air and fuel quantities at kiln considering design parameters of the cement plant by keeping adequate safety factors at each level of calculations to assure that neither production rate nor quality of the clinker vary. Analysis of Heat balance was used to determine the sources of heat loss from the kiln s...
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Electrical and Exergy Analysis of a Simple Pass Photovoltaic–Thermal (PV/T) Air Heater with Slats Under Weather Conditions of the Far Nord Region, Cameroon
Paiguy Armand Ngouateu Wouagfack,
Ariane Laurelle Ngankou,
Noël Djongyang,
Réné Tchinda
Issue:
Volume 4, Issue 2, April 2019
Pages:
33-43
Received:
23 March 2019
Accepted:
23 April 2019
Published:
26 May 2019
Abstract: In this paper, a simple pass photovoltaic-thermal air heater system with slats has been considered to study its electrical and exergy performance by theoretical and numerical analysis. The collector has been modeled in such a way that the absorber plate is totally covered by photovoltaic modules. The climatic data (solar irradiation, ambient temperature) of the Far Nord region of Cameroon have been used. Thin metallic strips called slats have been attached longitudinally at the bottom side of the absorber plate of the system. The first and second laws of thermodynamics have been applied to write the equations describing the functioning of the system. These equations have been solved by numerical computation using the gradient conjugate method. The influences of some operating parameters on the electrical and overall exergy efficiencies were investigated. It was found that (i) it is of great importance to use slats as an integral part of the absorber surface in order to achieve better efficiencies of single pass photovoltaic-thermal systems and (ii) the instantaneous overall electrical and overall exergy efficiencies of a simple pass hybrid (PV/T) solar air heater varies between 9-12% and 11,5-18,5% respectively.
Abstract: In this paper, a simple pass photovoltaic-thermal air heater system with slats has been considered to study its electrical and exergy performance by theoretical and numerical analysis. The collector has been modeled in such a way that the absorber plate is totally covered by photovoltaic modules. The climatic data (solar irradiation, ambient temper...
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Effects of Varieties and Intra Row Spacing on Yield of Maize (Zea mays L) Under Supplementary Irrigation in an Arid Region of Western Ethiopia
Issue:
Volume 4, Issue 2, April 2019
Pages:
44-50
Received:
16 March 2019
Accepted:
6 May 2019
Published:
31 May 2019
Abstract: Determination of optimum plant population and the use of improved varieties in combination with appropriate agronomic practices are important components of maize production package for maximizing productivity. The study was conducted 2017- 2018 under supplementary irrigation at 9o 10' 00'' N' latitude and 35o22' 00′′ E longitude, Western Ethiopia, to determining the effects of variety and intra-row spacing on yield of maize (Zea mays L.), the same application of irrigation water. The experiment was conducted in factorial arrangement of four intra-row spacing (20, 25, 30 and 35cm) with three maize varieties (BH546, Shone and BHQPY-545) in RCBD. The interaction of variety and intra-row spacing was highly significant (P<0.01) on yield components and yield of maize. The highest (1.75) average number of ears per plant was recorded from varieties BH546 and BHQPY-545 at 35cm intra-row spacing. The highest (35cm) ear length was recorded from BH546 at 35cm intra-row spacing. Generally, leaf area, stand count, ears per plant, ear length, and ear diameter showed a decreasing trend with decreasing intra-row spacing. Based on these results, it can be tentatively concluded that the variety BH546 could be used at plant density of 53,333 plants ha-1 and (25cm) intra-row spacing is best to get the highest green cob yield of maize under supplemental irrigation during the off-season in the study area.
Abstract: Determination of optimum plant population and the use of improved varieties in combination with appropriate agronomic practices are important components of maize production package for maximizing productivity. The study was conducted 2017- 2018 under supplementary irrigation at 9o 10' 00'' N' latitude and 35o22' 00′′ E longitude, Western Ethiopia, ...
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Design and Simulation of Photo-voltaic Water Pumping System for Irrigation
Issue:
Volume 4, Issue 2, April 2019
Pages:
51-63
Received:
19 March 2019
Accepted:
14 May 2019
Published:
12 June 2019
Abstract: In locations where electricity is not available, other means are necessary to pump water for different applications. Using a diesel pump to deliver water causes economic and environmental problems. The higher price of diesel increases operation costs of diesel water pumping system thereby reducing the incomes. In addition, the use of a diesel pump emits a considerable amount of CO2 which cause global warming. A possible solution to these problems is using renewable energy source like solar power, which is environmentally friend and available for free. This paper presents the design and simulation of a photovoltaic water pumping system for irrigation of a potato farm located at a place named Gerenbo in south-west Ethiopia. The system was designed by considering the site’s topography and local meteorological data. The PV system designing was made in such a way that, capable of irrigating a hectare area potato farm with daily water requirement of 7m3 and total dynamic head of 21m. To run simulations, different tools have been used. Those include CROPWAT, MatLab, and HOMER. Furthermore, after seizing all components and sub-systems, the entire system (from solar radiation to water production) was simulated by using PVsyst. The economic and environmental aspects of PV water pumping systems have been studied. Based on the projected system lifetime production, the equivalent cost of water for PVWPs and DWPs is $0.1187/m3 and $0.3526/m3 respectively. Replacement of diesel-powered water pumping system results in an annual reduction of CO2 emissions by 1500kg.
Abstract: In locations where electricity is not available, other means are necessary to pump water for different applications. Using a diesel pump to deliver water causes economic and environmental problems. The higher price of diesel increases operation costs of diesel water pumping system thereby reducing the incomes. In addition, the use of a diesel pump ...
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Challenges of Female Students Academic Achievement: The Case of Debre Markos University
Issue:
Volume 4, Issue 2, April 2019
Pages:
64-71
Received:
15 October 2018
Accepted:
28 December 2018
Published:
12 June 2019
Abstract: Females have their own contribution in economic, political and social aspects of a country. Educated females are taking a lion share in a country’s development. In Ethiopia female students’ participation at university level is growing time to time. But, the numbers of female students who graduate from the universities are low compared with male students because of different challenges. This study was conducted with the objectives of to investigate the challenges of female students’ academic achievement in the case of Debre Markos University. To meet this objective the researcher employed on qualitative research approach with case study design method. The participants selected by using non probability sampling technique specifically purposive sampling. The data sources were primary data. Semi-structured interview and FGDs were used as a tool for collecting primary data. The data were analyzed using thematic analysis methods. The findings from the study revealed that female students are facing different challenges. Such as, institutional challenges like lack of special support, problem of academic advisor, lack of orientation, low facilities, instructors lack of teaching skills, crowded classroom, drastic life change, sexual harassment and personal challenges such as, poor socialization, lack of interest, low self-confidence, stress, poor study habit, lack of money, gender related problem, low follows up, poor language ability, lack of commitment. The study has concluded that female students are faced with many institutional and personal challenges. Based on the conclusion, recommendations are forwarded in line with the major finding of the study.
Abstract: Females have their own contribution in economic, political and social aspects of a country. Educated females are taking a lion share in a country’s development. In Ethiopia female students’ participation at university level is growing time to time. But, the numbers of female students who graduate from the universities are low compared with male stu...
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