Mechanical and Industrial Engineering

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    Feasibility Study and Energy Management System of Mini Grid Hybrid Systems for Energy Intensive Industries: A Case Study of Industries in Mekelle
    (Mekelle University, 2025-05-30) Hiwot Nigusie
    Hybrid systems integrate renewable energy sources with battery storage to supply energy in offgrid or on-grid setups. Many studies on hybrid power generation focus primarily on rural electrification, the socio economic benefits for households and local communities and remote areas, often overlooking the impact on industrial development. This literature gap limits our understanding of how reliable electricity access could drive industrial growth, enhance productivity, and foster economic diversification. This study focused on the techno-economic feasibility of a mini hybrid power generation system for electrification of three energy intensive manufacturing industries that are located in Mekelle city of Tigray namely Mesfin Industrial Engineering, MOHA soft drinks industry, and Desta Alcohol & Liquor Factory. The aim was to study the feasibility of a hybrid renewable energy solution to make industries energy independent and provide sufficient power and tied them with reliable power system by avoiding their grid dependency. The software packages utilized is used to design, analyze, and optimize the hybrid power system were HOMER Pro modeling tool. The mini grid has a peak capacity of 230 kW requires 3005 kWh/day. The Generic PV system has a nominal capacity of 720 kW. The annual production is 1,321,381 kWh per year for Mesfin Industrial Engineering. The electric needs for MOHA soft drinks industry are met with 720 kW of PV, 320 kW of generator capacity, 330 kW of wind generation capacity with operating costs for energy of $388,003 per year without battery storage. An addition of 1,000 kWh of battery capacity is proposed. This will reduce the operating costs to $458,636 per year. A 50 kW of generator capacity, 1,000 kWh of battery capacity and for Desta Alcohol & Liquor Factory 50 kW of wind generation capacity, with operating costs of $154,451 per year. It is proposed that adding 110 kW of hydropower generation capacity would reduce operating costs to $154,421/yr.
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    Design and Experimental Evaluation of passive Solar Still under hottest and driest climate condition of Ethiopia: A case of lake-Afdera saline water
    (Mekelle University, 2024-12-25) Mohammed Ahmed Yasin
    Access to potable water remains a critical challenge globally, particularly in arid regions such as Ethiopia's Afar Region, where groundwater is often limited or contaminated with high levels of fluoride and salinity. This study investigates the design and performance of passive solar stills for desalinating saline water from Lake Afdera under extreme climatic conditions. The objective was to enhance the productivity of conventional single-slope, single-basin solar stills by incorporating black volcanic rocks as thermal energy-absorbing materials. Two solar still configurations a conventional design and a modified design with black volcanic rocks were constructed and experimentally evaluated over two days in Afdera. Parameters such as ambient temperature, water temperature, and hourly yield were recorded. To validate the results, the modified still was later tested under different environmental conditions at Mekelle University using thermocouples, PicoLog software, a pyranometer, and measuring jars for precise data collection. Results showed that the modified solar still significantly outperformed the conventional still in water yield, producing 3,482 ml and 3,800 ml over two days compared to 1,920 ml and 1,780 ml, respectively. It also demonstrated improved night-time performance, yielding 890 ml versus 340ml, due to better heat retention from the black rocks. Correlation analysis from the Mekelle validation indicated strong relationships between water yield and solar radiation (r = 0.60), rock temperature (r = 0.96), internal temperature (r = 0.85), and ambient temperature (r = 0.83). The modified system achieved 32.87% higher efficiency in Afdera than in Mekelle, highlighting the role of environmental conditions. The findings confirm that integrating black volcanic rocks into solar still design enhances efficiency and output, offering a cost-effective and sustainable desalination solution for arid, high radiation regions like Afar.
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    Feasibility Study of Integrated Hybrid Energy System for off-Grid Rural Electrification: Case of Three Village
    (Mekelle University, 2024-09-28) Yeshareg Yrgalem
    This research presents a feasibility study of an integrated hybrid energy system designed for off grid rural electrification in three villages in Ethiopia's Tigray region. With over 56% of Ethiopia's population lacking access to electricity, the National Electrification Program (NEP) aims to achieve universal electricity access by 2025, promoting a mix of grid and off-grid solutions. This study explores the potential of combining wind, solar, and biogas to create a sustainable energy model that aligns with the NEP's objectives. The objectives of this study are threefold: to assess the renewable energy resources available in the selected villages, to design and size the components of a hybrid energy system, and to evaluate the technical and economic feasibility of the proposed solution. The methodology involves data collection through site assessments, resource evaluations, load estimations, and modeling using the HOMER Pro software. The study evaluates the energy demands of Felege Mayat, May Shih, and Mayderhu villages, revealing daily energy requirements of 1673 kWh, 1215 kWh, and 785 kWh, respectively. The findings indicate that a hybrid system—combining wind, solar, and biogas—can deliver a sustainable, reliable, and cost-effective electricity supply, with levelized costs of electricity (COE) at $0.0139/kWh, $0.0158/kWh, and $0.0167/kWh for each village. This approach not only addresses the immediate energy needs in these rural communities but also promotes environmental sustainability by reducing dependence on traditional biomass. In conclusion, this thesis highlights the potential of integrated hybrid energy systems to bridge the energy gap in rural Ethiopia, promoting sustainable development and improving human wellbeing. Recommendations for future research and implementation strategies are provided to facilitate the adoption of such systems in similar contexts.
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    Experimental Study on the Effect of Operating Parameters on Hydrogen Production from Alkaline Wastewater Electrolysis
    (Mekelle University, 2024-12-28) Yibrah Gebrecherkos
    This study investigated the influence of three principal operating parameters on hydrogen production from alkaline wastewater electrolysis. Hence the primary objective of this study was to examine the effects of specific operating conditions on hydrogen yield, employing alkaline wastewater as electrolyte. The key parameters examined included temperature variation, effect of electrolyte concentration variation, and applied current variability. The findings indicated that electrolysis performance was significantly influenced by these parameters. Specifically, the volume of hydrogen produced rose with rising current. At the tested currents of 0.3A, 0.5A, 0.7A, and 0.8A, the time needed to reach 10 ml of hydrogen was 664.88s, 349.24s, 244.21s, and 230.08s, In addition efficiency rose with each added current, 41.122%, 46.973%, 50.322%, 47.982%, and 44.562%. Higher applied currents initially enhanced the yield. However, beyond a certain threshold, further increases in current lead to a decline in efficiency owing to limitations in mass transport and bubble formation in and around the cell. Regarding the effect of temperature and electrolyte concentration on the rate of hydrogen production, as the temperature raised at 10 K intervals (303.15, 313.15, 323.15, 333.15, and 343.15 K), the time needed to reach 10 ml of hydrogen by volume reduced in higher order of magnitude (312.61, 267.61, 233.96, 189.72, and 184.18 s, respectively). In addition, the efficiency of the hydrogen production rate improved at each added current: 45.173%, 51.84%, 56.623%, 62.31%, and 67.735%. Although high temperatures improve efficiency, they are not favored because of the higher operating costs. The effect of the electrolyte concentration was also significant in terms of the hydrogen rate. At a current of 0.25 A for all ranges of concentration tested (5, 10 g/l; 15g/l and 20 g/l NaOH), the time(s) to reach 10 ml by volume of hydrogen was 341.58s, 276s, 236.18, and 209.57 s, respectively. This was due to the higher ionic mobility with an enhanced concentration of the electrolyte. Generally, the hydrogen production yield reached approximately 57% efficiency at a temperature of 323.15 K, current of 0.6A, and concentration of 10 g/NaOH from the alkaline wastewater, highlighting the potential of this method for generating hydrogen from an abundant and environmentally friendly resource. Future research should focus on further optimization strategies, long-term stability of electrodes in wastewater electrolysis, and economic feasibility of scaling up this process for practical applications.
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    Development Of Solar Absorption Refrigeration System for Off-Grid Application
    (Mekelle University, 2025-07-02) Merhawit G/medhin
    Electricity has a vital role in improving the quality of life as it is used in activities such as lighting, heating, air conditioning, refrigeration, transportation, health, communication, entertainment, etc. Lack of electricity can affect the health and agricultural sectors as many of vaccines and agricultural products go to waste to the absence of proper preservation facilities. To minimize cold preservation problem, a vapor absorption refrigeration system which operates by solar energy was developed, manufactured and experimentally tested. The system use dammonia -water refrigerant absorbent combination. From the cooling load analysis capacity of the system was computed as 55W which is relatively low but enough for the prototype. The system uses 0.39 m² area of the flat plate collector and the solar radiation intensity on inclined surface of the location obtained was about 784 W/m². The calculated COP of the system was 0.45, with a generator heat input of 120.9 W. This result is favorable when compared to prior studies, which reported COPs in the range of 0.1 to 0.4. The experimental tests recorded absorber plate and generator temperatures of 100°C and 80°C,n respectively. While the generator performance yielded favorable results, further system evaluation was hindered by ammonia leakage. Despite the inability to conduct additional tests due to limited ammonia solution availability, the overall findings indicate with improvements in system sealing and ammonia supply, the proposed system shows promise for rural healthcare and agricultural preservation
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    DETERMINATION OF SPECIFIC HEAT CAPACITY FOR FOOD ITEMS
    (Mekelle University, 2025-02-25) Goitom Zeberhe Gebeya
    The primary objective of this study was to determine the specific heat capacity of various food items experimentally. The study involved the development of the experimental setup and the execution of the experiment on some selected food items. An indirect calorimetric method of mixture experimental setup has been developed to determine the specific heats of some selected foods and prepared traditional foods mainly found in Ethiopia, which is commonly known as Injera. This method involved the modification of a heat preservation portable food storage container, purchased from a local market, to serve as a calorimeter. The calorimeter utilized in this study was a 1.9-liter wide-mouth, vacuum flask designed to keep food at a desired temperature for an extended period by minimizing heat transfer with its surroundings. Initially, four runs were conducted for the determination of the calorimeter’s specific heat capacity by employing hot water, which is found to be an average 1.003 kJ/oC. It is important to note that the plastic pouch is considered to be an integral component of the calorimeter, as both the calorimeter and plastic pouch were acquired from the local market. To prevent direct contact between the food sample and the heat exchange medium within the calorimeter, the food sample was placed within the plastic pouches. Consequently; the assessment of heat solution for dissolved chemicals in food was eliminated. The specific heat values of carrots, potatoes, onions, cabbage and Injera using predictive models at an average temperature were determined as 4.365, 4.086,4.423, 4.505 and 3.433 kJ/(kg oC), and the experimental results of these foods were found to be 4.671, 4.290, 4.688, 4.820 and 3.710 kJ/(kg oC) respectively, here the same amount of mass of samples and water, materials and methodology, by the indirect method of a mixture of calorimetry is used. Also four trials are were conducted for the determination of the specific heat capacity of potatoes, carrots, onions, cabbage and Injera. The comparison between the experimental and the predictive models exhibited an excellent level of agreement with percentage error of 5% to 10% for the above foods. This indicates that experimental specific heat capacity measurement is consistent and validate with the predictive value within an acceptable range of error.
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    Design and Numerical Analysis of a Solar-Based Thermal Energy Storage System for Industrial Hot Water: A Case Study at Addis Pharmaceutical Factory (APF)
    (Mekelle University, 2025-07-01) Eyob Kahsay
    Solar thermal energy storage (TES) provides a sustainable solution to growing energy demands by storing excess solar energy for later use, particularly in regions with high solar availability. With rising fuel costs and increasing greenhouse gas emissions, adopting energy efficiency improvements and integrating renewable energy sources are crucial in our country, Ethiopia. At APF, furnace oil consumption for process heating is substantial. Additionally, air conditioning (HVAC) systems and process heating rely on hot water produced by an indirect furnace oil system. In this setup, steam is generated in a boiler and then used to produce hot water through a heat exchanger. This is due to water being preferred over steam for certain applications it is easier to control. At APF, 32.5% of the total furnace oil consumption is allocated for hot water production, resulting in an annual cost of approximately 2.88 million birr. This study focuses on the design, analysis, and modeling of a solar-powered TES system for hot water consumption at APF, aiming to enhance system efficiency by selecting the optimal heat transfer fluid (HTF) and energy storage material based on thermal performance and cost-effectiveness. The research evaluates three TES methods: sensible, latent, and thermochemical storage. While phase change materials (PCMs) offer high energy storage density, they have material limitations. Sensible heat storage, despite being cost-effective, has a low heat capacity, making storage units impractically large. Chemical heat storage, though providing high storage density, is hindered by complex reactor designs and stability concerns. Key parameters such as HTF mass flow rate, heat transfer coefficient, flow velocity, and Reynolds number were calculated. The study also includes thermal design analysis, Computational modeling, and performance simulations. The results include calculations of boiler power, total energy consumption, water mass flow rate, energy storage capacity, and trough area. Additionally, SolidWorks geometric modeling was utilized to visualize the concept and aid in solution development. The findings demonstrate the potential of the designed TES system to improve energy efficiency, reduce operational costs, and lower greenhouse gas emissions, contributing to the advancement of sustainable thermal energy storage solutions. Based on comprehensive thermal analysis and ANSYS computational simulations, Shell Heat Transfer Oil S2 was identified as the most effective HTF, while Sodium Thiosulfate Pentahydrate was determined to be the optimal storage material for low- to medium temperature applications. Additionally, an optimal insulation thickness of 16 mm was found to minimize energy loss and cost. To mitigate the intermittent nature of solar energy, the TES system addresses the annual operating cost saving of 0.58 million birrs for the eight-hour operating period, which is 58.2 kW.
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    Enhancing Labor Productivity of Garment Firms by Mixed Arena Simulation and Taguchi Design of Experiments (Case Company: MAA Garment and Textile Factory)
    (Mekelle University, 2025-09-08) Medhin Haleslase
    This study presented a mixed Arena simulation and Taguchi experimental design approach to improve productivity in garment factory, with a focus on the round neck T-shirt production line at MAA Garment and Textile Factory. This production line was observed to influence the overall performance of the company highly for its low operator output, longer idle times and lower average resource utilizations. Realistic modeling of the production environment was ensured by fitting appropriate statistical distributions (e.g., normal, triangular, exponential and etc.) to each operation’s processing time, based on data collected through time studies. These distributions were selected using Arena Input Analyzer, which applies goodness-of-fit tests with the Kolmogorov Smirnov test method to determine the best fit for the observed data. Informal interviews with operators and line supervisors were conducted as well to gain an understanding of the variability and operational arrangements. The development of a verified simulation model and the development of dependable Taguchi experiments were made feasible with these inputs. Discrete-event simulation was used to model the existing production system using Arena software, enabling detailed analysis of flow dynamics, bottlenecks, and resource utilization. Two key operational factors; batch size and operator skill level were selected for experimental analysis using the Taguchi method with an L9 orthogonal array. Performance was evaluated based on three response parameters: throughput, average waiting time, and resource utilization. Signal-to-Noise (S/N) ratio analysis and main effects plots were employed to identify optimal factor settings that deliver stable and improved system performance. The results revealed that a batch size of 20 and high operator skill level yielded the most consistent gains in throughput and utilization while reducing delays. The optimized scenario, when re-simulated, showed notable improvements; 835-860, 779-743 and 68.3-70.8 (i.e., +3% throughput, -4.6% Average Waiting Time and +2.5% utilization) respectively, compared to the existing system model. This study demonstrated the effectiveness of integrating Arena Rockwell simulation and Taguchi design of experiments (DOE) in identifying data-driven productivity strategies, offering a practical framework for performance enhancement in garment production lines. However, points such as estimated input distributions due to lack of secondary data sets, limited factor analysis because of the limitations of Taguchi method were seen as the basic limitations of this study.
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    Impact of network embeddedness and Innovation Capability on the Innovation performance of SMEs through Innovation Openness
    (Mekelle University, 2025-09-10) Berey Halefom
    Small and medium-sized enterprises (SMEs) are essential for promoting innovation in economies. The process of developing novel concepts, procedures, goods, services, or solutions that significantly improve and add value is known as innovation. The idea of network embeddedness holds that social relationships impact an organization's economic behavior and that businesses can leverage their social networks to support their growth. The majority of empirical research on innovation focuses on high-tech, large-scale businesses in industrialized nations, and Ethiopia, the impact of network embeddedness and innovation capability on innovation performance has not been investigated before. The study aims to examine the impact of network embeddedness and innovation capability on innovation performance and the mediating role of innovation openness of SMEs. The study used an explanatory research methodology and a structured questionnaire to gather primary data from 222 manufacturing small and medium enterprises operating in Mekelle, Tigray, Ethiopia. The data was analyzed using IBM SPSS v20 and AMOS v20 and confirmed factor analysis (CFA) was employed to assess the validity and reliability of the results. The findings of the study revealed that network embeddedness has a significant impact on open innovation and innovation performance of SME firms. Furthermore, product innovation capability has a significant impact on open innovation. Although product innovation capability has an insignificant impact on the innovation performance of SMEs. Additionally, open innovation has a significant indirect effect between network embeddedness, and product capability on the innovation performance of SMEs. The findings of this study provide to maintain innovation performance based on the theoretical concept of social network theory and resource-based view and Firm owners/ managers, and policymakers should continuously enhance their innovation capabilities.
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    The Impact of Ergonomic Risk Factors on Musculoskeletal Disorders and Their Implication to Productivity Through Rapid Entire Body Assessment (REBA): A Case Study at ALMED Textiles Plc.
    (Mekelle University, 2025-08-25) Samuel G/her
    Musculoskeletal disorder (MSDs) is one of the most common occupational health conditions globally, especially in the labor-intensive sector like textile & garment manufacturing. This study examines the impact of ergonomic risk factors on the prevalence of MSDs & their implication for the operator’s productivity at ALMEDA Textiles., a major garment manufacturer in Ethiopia. The study employs a cross-sectional design, combining observational method, REBA posture analysis tool along with a validated instruments such as CMSDQ & WPAI questionnaire to comprehensively assess ergonomic risk, & productivity loss. Data were collected from 295 operators across the garment department with a response rate of 93.35%. A key finding revealed that 75.8% of operators have reported symptoms of MSDs, specifically in the lower back, neck, shoulder wrist & knee. MSDs were prevalent, with 34.9% experiencing neck pain and 37.6% experiencing lower back pain daily. productivity losses averaged 43.87%, driven by absenteeism & presenteeism linked to MSDs. The finding also shows 90.8% (REBA score 8-10) of workstations posed high ergonomic risks, primarily due to awkward posture, repetitive motions & prolonged static loading. Regression analysis identified demographic risk factors (β=1.058, P=0.001), job related risk factors (β=0.491, P=0.001), psychological risk factors (β=0.306, P=0.001), & physical risk factors (β=0.187, P=0.008) as significant predictors of MSDs. The study highlights critical gaps in ergonomic training & workstation design, with 95.6% of operators lacking ergonomic awareness. Recommendations include workstation redesign, mechanical aids & targeted training; such measures are vital for reducing MSD risks, improving operator well-being & enhancing productivity. This research contributes to the ergonomic literature in post-conflict industrial settings with a multidimensional view (utilizing a combination of REBA, CMDQ & WPAI) & offers actionable insights for improving worker health & productivity in Ethiopia’s garment industry. For further investigation, researcher should explore the economic return of ergonomics investments analyzing how redesigns, training, & health focused initiatives translate into cost saving & efficiency for manufacturing firms. Relaying solely on self-reported data my introduce response bias due to underreporting or over reporting of symptoms. furthermore, Cross sectional design capture data at a single point in time.