East African Journal of Engineering

An ICT-Integrated Predictive Maintenance Model for Enhancing Plant Availability in Thermal Power Plants: A Case Study of TANESCO, Tanzania

2026-01-01T17:24:35+00:00

The thermal power sector in Tanzania faces increasing operational complexities and maintenance challenges that undermine plant reliability and efficiency. This paper focuses on the TANESCO Ubungo II Gas Plant, where recurring issues highlight the urgent need for advanced and sustainable maintenance strategies. The paper proposes a predictive maintenance model that integrates Process Control System 7 (PCS 7) with a Computerised Maintenance Management System. A mixed-methods approach was employed, combining qualitative insights from literature and field studies with quantitative techniques, including regression analysis. Key variables influencing plant availability, uptime, downtime, overhaul frequency, operational expertise, and environmental conditions were analysed using multiple regression and the Relative Importance Index to determine their relative contribution to plant performance. The findings indicate that strategic integration of ICT within maintenance frameworks significantly improves the accuracy of failure prediction, reduces downtime, and enhances operational efficiency. The model demonstrates the potential to optimise maintenance schedules, extend asset life, and lower overall operational costs. This paper contributes to the growing body of knowledge on predictive maintenance in the energy sector and provides practical insights for enhancing power plant performance in Tanzania and other developing economies

Exploring Paka Geothermal Reservoir through 3D Visualisation and Gravity Data Inversion Modelling in Northern Kenya Rift

2026-01-12T19:13:30+00:00

The Paka geothermal field, located in the Northern Kenya Rift segment, is influenced by tectonic extension and magmatic activity that drives crustal uplift and hydrothermal circulation. While most previous gravity studies in this region targeted depths beyond 6 km, shallow intrusive structures crucial for geothermal resources remain poorly resolved. This study applied regional Bouguer anomaly mapping and 3D gravity inversion to characterise density variations, intrusive heat sources, and favourable structural settings for resource development. Gravity data were processed with a Bouguer density of 2.0417 g/cm3, anomaly separation through upward continuation, and 3D VOXI inversion in Geosoft Oasis. Results reveal a broad negative Bouguer anomaly (–126 to –103 mGal) about 20 km wide, with superimposed narrower anomalies (~5 km wide) in the northern caldera. These align with NW–SE, NE–SW, and N–S fault trends, consistent with regional tectonic structures. Near-surface pyroclastic sediments (0–250 m, 2.1–2.3 g/cm3) overlie a denser caprock (250–700 m, 2.25–2.45 g/cm3) interpreted as hydrothermally altered tuffs. At ~2.5 km depth, low-density zones (1.75–1.8 g/cm3) suggest water reservoirs or altered tuffs. A high-density mafic intrusion, likely of trachytic to basaltic magma origin, was identified between 2.0 and 3.1 km depth (volume ~475 ±10 % km3; 2.50–2.90 g/cm3), serving as the primary heat source. The associated reservoir beneath the summit lies at ~2.2 km depth with an estimated volume of 120 ±10 % km3. Structural continuity links Paka to Silale and Korosi volcanoes along the rift axis. The findings of this study highlight the summit region as the most promising drilling target for sustainable geothermal development.

Computational Modelling and Numerical Simulation of a Lead-free Perovskite Photovoltaic Solar Cell, Optimised for the Specific Climatological Profile of Zimbabwe

2026-01-19T11:09:05+00:00

This study entails the computational design and numerical simulation of a lead-free perovskite photovoltaic solar cell, optimised for the specific climatological profile of Zimbabwe. The investigation addresses the critical limitations of conventional perovskite solar cells, namely Pb-toxicity and thermo-environmental instability, by proposing a novel heterostructure NiO/CsSn₀.₅Ge₀.₅I₃/ZnO/FTO in the context of the Zimbabwean climatic conditions. The core of the design is the all-inorganic halide perovskite absorber layer, CsSn₀.₅Ge₀.₅I₃, where the isovalent cation substitution of Sn²⁺ and Ge²⁺ for Pb²⁺ constitutes an eco-friendly alternative. The device architecture employs a hole transport layer of NiO and an electron transport layer of ZnO, deposited on an FTO substrate, forming a conventional n-i-p configuration. Using the Solar Cell Capacitance Simulator software, the device's performance metrics were evaluated under a temperature gradient (8°C to 35°C) reflective of the operational environment. The results demonstrate exceptional thermal resilience. In addition, the analysis reveals a minor degradation in open-circuit voltage from 1.2376 V to 1.2045 V, attributable to increased intrinsic carrier concentration and enhanced Shockley-Read-Hall recombination at elevated temperatures. Notably, the short-circuit current density remained invariant at ~27.24 mA/cm², indicating stable photogeneration and charge collection efficiency. Consequently, the fill factor and power conversion efficiency exhibited only marginal declines from 90.39% to 89.52% and 30.48% to 29.38%, respectively. The simulation confirms the viability of the proposed multi-cation perovskite composition and device stack, achieving a stabilised PCE exceeding 29% across the specified thermal range. This work underscores the efficacy of computational modelling with SCAPS-1D for the a priori optimisation of PV device architectures, thereby de-risking the R&D pipeline by minimising empirical iteration. The findings contribute to the development of regionally tailored, high-performance, and sustainable third-generation photovoltaics.

A Study of the Mathematical Aspects of Some Selected Conformal Mapping Airfoil Design Theories and Their Applications

2026-01-28T11:28:09+00:00

This paper discusses the mathematical aspects that undergird two conformal mappings that are commonly used in airfoil design and well-known to most aeronautical engineering practitioners, namely, the Joukowski and Schwarz-Christoffel transformations. It orients the reader with the necessary analytical complex-analysis tools required in the derivation and application of these mappings. The paper explores how the Schwartz Christoffel theorem transforms a unit circle into an airfoil that is envisaged as a polygon divided into n linear segments called panels. Both transformations are well catalogued, with more emphasis being placed on the Joukowski mapping, which is more commonly used. To accomplish this, the generalisation of the Joukowski transformation is progressively developed from the simple mapping of the circle into an ellipse. Subsequently, the desirable cambering effect, which is attained both by varying the parameter of transformation λ and offsetting the centre of the transformation, is explored and validated for a circle of radius 1.24 centred alternatively at -0.24+0i, and -0.22+0.28i. This transformation is presented diagrammatically to enhance the visualisation of how the Joukowski transformation maps a cylinder (or circle) into an airfoil. In the end, the Joukowski transformation in particular is reaffirmed as an important framework for the achievement of optimal characteristics in the preliminary design phase of wings and airfoils. Throughout the paper, the fluid flow is assumed to be two-dimensional, irrotational under gravitational influence, incompressible, steady, and inviscid, and to have negligible dissipative viscous forces. All boundary layers and wakes are assumed to be vanishingly thin.

Synthesis of Microgrid Model for Scalable Hybrid Renewable Energy Power Generation

2026-02-03T15:02:44+00:00

Renewable Energy Sources (RESs) such as solar, wind, and biodiesel are considered clean energy sources for power stations. However, the difficulty in extracting power from these RESs is due to dynamic fluctuations in weather parameters, especially in wind and solar PV systems. Besides, using solar PV-wind power generation in stand-alone mode would require larger storage devices to compensate for the fluctuating nature, which would make the overall system more expensive. Hence, a proposed hybrid system of solar PV, wind, and biodiesel is suitable to enhance reliability and reduce the Battery Energy Storage System (BESS) requirements. In the proposed system, power generated from solar PV and wind was controlled using a modified Maximum Power Point Tracking (MPPT) controller due to the stochastic nature of these sources. The former direct MPPT controller using the Perturb and Observe (P&O) algorithm provide duty cycle that is compared with the carrier signal to control the boost converter. Therefore, it cannot regulate the DC bus voltage to the desired value. In order to regulate the DC bus voltage, the duty cycle of the direct MPPT controller is corrected through Proportional-Integral (PI) controllers. The biodiesel source was controlled by using a PI controller due to the production of a constant generated output voltage. The output voltages from the three sources were integrated at a common DC link with the BESS to control the voltage variation of the DC bus for dynamic DC loads. Thereafter, the DC bus was connected to the voltage source converter (VSC) operated as an inverter using voltage and frequency control at the Point of Common Coupling (PCC), where the AC loads are connected. The proposed design of a hybrid Solar PV-wind and biodiesel system was modelled and simulated using MATLAB/Simulink software. On testing the performance of the system, it was observed that the voltage and frequency at the AC load were maintained constant at 1 pu and 50 Hz, respectively. This type of energy source is feasible for use in rural areas of most Sub-Saharan African countries, including Tanzania, either under isolated or as grid-connected.

Quantitative Assessment of Key Performance Indicators Influencing the Pavement Condition Index for Cold Mix Asphalt Pavement in Low Volume Roads

2026-02-03T15:03:11+00:00

This study quantitatively examines the factors affecting the performance of low-volume cold mix asphalt pavements using a data-driven analytical framework. Documented field records and historical pavement performance data from costal region were used to evaluate seven Key Performance Indicators (KPIs): Rutting Depth (RD), International Roughness Index (IRI), Crack Density (CD), Moisture in Subgrade (MS), Traffic Load (TL), Rainfall (RF), and Binder Content (BC). Descriptive statistics, Stability Index (SI), correlation analysis, and a combined weighting method were applied to assess deterioration patterns and the relative influence of each KPI on the Pavement Condition Index (PCI). Correlation analysis showed strong negative relationships between PCI and RD (-0.99), IRI (-0.995), CD (-0.985), MS (-0.997), TL (-0.995), and RF (-0.992), indicating declining pavement condition with increasing distress, loading, and environmental factors. BC demonstrated a strong positive correlation (0.991), highlighting its significance in maintaining pavement durability. Stability Index results identified BC (SI = 16.953) as the most stable and reliable parameter, while CD (SI = 1.017) and RD (SI = 1.339) were the most variable. The combined weighting analysis ranked BC (23%), RF (19%), and MS (18%) as the most influential KPIs, followed by TL (17%) and IRI (14%), with RD (7%) and CD (2%) having lower impacts. Min–max normalization ensured comparability across variables with different units and scales, and radar plots were used to visualise overall KPI contributions. The study provides a comprehensive evidence base for predictive modeling of PCI and recommends improved binder design, moisture control, traffic regulation, and timely maintenance to enhance pavement service life and performance

The Mechanical Studies of Special Concrete with Pozzolan Subjected to Elevated Temperatures

2026-02-06T18:08:44+00:00

Concrete is a fundamental building material, but its performance under high temperatures raises concerns about structural safety and resistance, particularly in fire scenarios. Standard concrete experiences significant strength and integrity loss or compromise when exposed to elevated temperatures. This is a critical concern for structures like chimneys, industrial facilities, bakeries and fire-resistant buildings. Traditional concrete experiences a decline in strength, cracking, and spalling (flaking) upon heating. Sand and pozzolan samples were collected from Wum, Menchum Division in the North West Region of Cameroon and were analysed using standard methods, according to the Cameroonian prescribed standards. The plain concrete was mixed with sand, gravel and normal Portland cement CIMAF 42.5R. The concrete was then stabilised with pozzolan as a partial replacement for sand. For the partial replacement, 10% and 20% were used. Curing was done for 7days, 14days and 28days and later subjected to controlled temperatures of 20℃, 120℃, 250℃ and 300℃, before crushing. The compressive strength showed that concrete of 20% pozzolan in the partial replacement of sand gives a compressive strength of 25.67MPa when subjected to a temperature of 300℃ after 28days of curing. Also, as the temperature increased from 250℃ to 300℃, the compressive strength of concrete increased, which can be explained by the fact that pozzolan is a volcanic ash and is formed under extreme temperature and thus has fire resistance properties, due to high temperature stability. Concrete made with 20% pozzolan replacement with the strength of 23MPa at room temperature and 25.67Mpa at elevated temperature of 300℃ can be used for all structural elements with the same specifications but higher resistance to fire and elevated temperatures. Pozzolan in small percentages can be very good for fire-resistant structures like chimneys, fireways, and local baking ovens.

Development of an Optimisation Model of Air-Cooled Chiller Maintenance Management to Improve Availability Performance

2026-02-06T18:08:44+00:00

Air-cooled chillers remain important to climate control in many industries. However, ensuring high availability of such systems has remained a big challenge to their operations, especially in developing countries like Tanzania. The maintenance practices currently adopted are mainly reactive, translating to a frequent occurrence of failures that result in shortened equipment life and energy wastage. In this paper, an optimum data-driven model is developed and validated for managing the maintenance of air-cooled chillers to advance the performance of their availability. Quantitative and qualitative data were collected from seven chillers at Julius Nyerere International Airport using a mixed-methods methodology approach at Dar es Salaam, including operations records, performance indicators, and interviews with experts. Multiple regression analysis highlighted preventive maintenance frequency (β = 0.312), compressor performance (β = 0.241), control system reliability (β = 0.225), and energy performance (β = 0.202) as the strongest positive determinants of availability. Contrary to findings in other studies performed under more extreme climates, environmental factors such as ambient temperature and dust had low significance. This can be explained by the stable coastal climate of Dar es Salaam and the relatively controlled infrastructure at JNIA. The model was then validated with an average prediction accuracy of about 98%. This was indicative of its efficiency in predicting the availability of chillers.

Development of a Maintenance Management Model for the Water Distribution Network to Enhance Water Availability

2026-02-09T14:21:51+00:00

The majority of water distribution networks in developing countries suffer from chronic water scarcity and high non-revenue water (NRW), largely due to inefficient maintenance processes. This study addresses this critical issue by developing and testing a proactive Maintenance Management Model for the North Mwika, Tanzania water supply network, which, despite sufficient raw water capacity, has a 47% NRW level. With an explanatory sequential mixed-methods design, questionnaires, focus group discussions, and document reviews were employed in data gathering from 50 stakeholders, engineers, technicians, and members of the community. The Relative Importance Index (RII) analysis indicated that the leading technical factors impeding performance were sediment blockages (RII=1.000), valve faults (RII=0.996), and network design deficiencies (RII=0.984), while tight budgets and slow response times were the foremost operational constraints. Regression analysis testified to the strong negative impact of these technical conditions (e.g., sediment clogging, B=-0.210, p=0.000) and positive contribution of adequate resources (e.g., budget, B=+0.095, p=0.010) on water availability. The predictive model developed was highly accurate, with 96% agreement between predicted and actual water reliability in five network zones. The study concludes that a paradigm shift is needed from reactive to proactive, data-driven maintenance. It suggests an integrated model of prioritised infrastructure rehabilitation, guaranteed funding for preventive maintenance, institutional capacity building, and greater community participation to successfully reduce NRW, improve water availability, and ensure the long-term sustainability of the water supply system.