Jurnal Teknik Indonesia

The Effect of Valve Opening on the Performance of an Archimedes Screw Turbine in a Micro-Hydro Power Generation System

Sulanjari Sulanjari, Joko Setiyono, Muhamad Miftahul Yamin — Sat, 12 Sep 2026 00:00:00 +0000

Water energy is one of the renewable energy resources with considerable potential for development in Indonesia. Micro-Hydro Power Plants (MHPPs) utilize the potential and kinetic energy of water from rivers, irrigation channels, or natural waterfalls to generate electricity based on the available head and water discharge. This study aims to analyze the effect of water discharge, regulated through variations in valve opening, on the performance of an Archimedes screw turbine in order to determine the operating conditions that produce the highest shaft rotational speed, generator output power, and turbine efficiency. An experimental method was employed using five valve-opening variations of 25°, 40°, 55°, 70°, and 85°, corresponding to water discharge rates of 0.00115, 0.00311, 0.00429, 0.00528, and 0.00802 m³/s, respectively. The results show that the maximum shaft rotational speed of 180.3 rpm was achieved at an 85° valve opening with a water discharge of 0.00802 m³/s. The highest generator output power of 5.35 W was obtained at a 70° valve opening with a discharge of 0.00528 m³/s. Meanwhile, the maximum turbine efficiency of 27.34% was achieved at a 40° valve opening with a water discharge of 0.00311 m³/s. These findings indicate that increasing water discharge does not necessarily result in simultaneous improvements in all turbine performance parameters.

Production of Lubricating Grease Using Non-Edible Soybean Sludge and Polypropylene as Complex Thickener

Wed, 07 Oct 2026 00:00:00 +0000

Conventional lubricating greases rely heavily on petroleum-derived thickeners and edible vegetable oils, raising sustainability and food security concerns. Sodium-based greases are cost-effective but suffer from poor water resistance, limiting their industrial application. This study aimed to formulate and evaluate a sustainable sodium-based multipurpose grease using non-edible soybean oil as base saponifiable feedstock and polypropylene as a performance-enhancing additive. : Sodium soap was produced via saponification of pre-treated non-edible soybean oil with 26% NaOH solution. Six formulations (F1-F6) were prepared by varying sodium soap content (100-600 g) at constant polypropylene (20 g) and base oil 900N (200 g). Physicochemical properties were evaluated according to ASTM standards: worked penetration (ASTM D217), dropping point (ASTM D2265), water washout (ASTM D1264), free acidity/alkalinity (IP 37), and water content (ASTM D95). Worked penetration decreased from 295 to 265 dmm, placing all formulations in NLGI Grade 2. Dropping point increased from 162°C to 195°C, exceeding the 150°C ASTM minimum. Water washout decreased significantly from 35% to 15% with increasing soap content, with formulations F2-F6 meeting the <25% requirement. Free alkalinity (0.03-0.05%) and free acidity (0.70-0.85%) remained within acceptable limits. Formulation F4 (400 g soap) exhibited optimal balance with 270 dmm penetration, 185°C dropping point, 20% water washout, and good adhesiveness.

Design of a Polyethylene Terephthalate (PET) Plant (SSP Unit) with a capacity of 270 tonnes Per Day

Wed, 07 Oct 2026 00:00:00 +0000

Demand for bottle-grade polyethylene terephthalate (PET) continues to grow, requiring energy-efficient solid-state polymerization (SSP) designs that reliably achieve high intrinsic viscosity (IV). This study presents the process design of a 270 tonnes per day PET SSP plant to produce bottle-grade resin from amorphous chip. Steady-state mass and energy balances, equipment sizing, and polymer property tracking were performed using established design correlations, kinetic models, and industrial operating data from Zimmer and Buhler technologies. The SSP train comprising pre-crystallizer, crystallizer, SSP reactor, chip cooler and nitrogen recycle was evaluated at 210°C and 10 h residence time. The design delivers 268.8 tonnes per day with 99.8% mass closure; 0.44 wt% loss corresponds to water, ethylene glycol and acetaldehyde removed. Net energy demand is 2.09 MW (0.185 kWh/kg), with the SSP reactor accounting for 46.7% of duty. IV increased from 0.60 to 0.80 ± 0.02 dL/g, while crystallinity rose from <5% to 48% in staged fashion, preventing agglomeration. Product moisture was <30 ppm and acetaldehyde <1.0 ppm. The selected conditions lie within proven commercial windows and meet all bottle-grade specifications. The design is technically feasible and provides a robust basis for economic evaluation and implementation.

Bioremediation of Oil-Contaminated Soil Using a Blend of Goat Manure and Cassava Peel

Wed, 07 Oct 2026 00:00:00 +0000

This study assessed the effectiveness of a blend of goat manure and cassava peel for the bioremediation of loamy soil artificially contaminated with Bonny Light crude oil. The experiment was conducted under laboratory conditions at the Department of Chemical Engineering, Imo State Polytechnic, Omuma, over a 60-day period. Loamy soil was spiked with 10% (w/w) crude oil and treated in three bioreactors: Reactor A (10% w/w cassava peel), Reactor B (10% w/w goat manure), and Reactor C (10% w/w 1:1 blend of goat manure and cassava peel). Soil samples were collected at 10-day intervals and analyzed for pH, total petroleum hydrocarbons (TPH), zinc (Zn), chromium (Cr), and microbial counts. Results showed that TPH decreased from an initial concentration of 18,500 mg/kg to 6,475 mg/kg, 5,180 mg/kg, and 1,850 mg/kg in Reactors A, B, and C, corresponding to 65.0%, 72.0%, and 90.0% reduction, respectively. Reactor C also achieved the highest reductions of Zn (51.5%) and Cr (62.5%), the greatest pH improvement from 4.85 to 7.55, and the highest proliferation of total heterotrophic and hydrocarbon-utilizing bacteria. Two-way ANOVA confirmed that treatment type, time, and their interaction significantly affected TPH reduction (p < 0.05). A multiple linear regression model developed for TPH prediction demonstrated excellent fit (R² = 0.942, R²adj = 0.939, RMSE = 420). The findings demonstrate that the synergistic blend of goat manure and cassava peel is a highly effective, low-cost, and eco-friendly biostimulant for enhanced remediation of crude oil-contaminated soils

Job Hazard Analysis as a Practical Tool for Process Safety Management: Methodology, Application and Performance Evaluation in High-Risk Industries

Wed, 07 Oct 2026 00:00:00 +0000

Process Hazard Analysis is central to Process Safety Management, yet system techniques like HAZOP are resource-intensive for task-level risks. Job Hazard Analysis (JHA) offers a practical alternative but lacks standardized evaluation. To develop, apply and evaluate a standardized JHA methodology for high-risk industries. A mixed-method study was conducted on 12 high-risk jobs involving 68 workers. A six-step JHA procedure based on OSHA 3071 was applied over 6 months. Performance was measured via risk reduction, JHA quality scores, TRIR and compliance rates. Data were analyzed with SPSS v26. 187 hazards were identified from 94 steps. High-risk hazards reduced by 83.8% after hierarchy-based controls. Mean JHA quality was 17.2/20. TRIR decreased from 4.85 to 1.92 (60.4% reduction, p=0.007). Permit compliance improved from 61% to 94%. Standardized JHA is an effective, low-resource tool for PSM, complementing HAZOP at task level.

Modeling Corrosion Progression and Optimizing Predictive Maintenance Strategies for Marine Vessel Hulls: An Engineering Case Study of Coastal Operations in Nigeria

Wed, 07 Oct 2026 00:00:00 +0000

Hull structural degradation due to marine corrosion remains a leading cause of unplanned dry-docking, cost overrun and safety risk for vessels operating in the aggressive tropical waters of West Africa. Conventional corrective maintenance often results in emergency steel renewal at excessive cost. This study develops and validates a predictive maintenance framework for hull steel renewal based on corrosion rate modelling, non-destructive testing (NDT) mapping and lifecycle cost optimization for operation in Nigerian coastal waters. AH36 hull steel (15 mm nominal thickness) was modelled using a uniform corrosion rate of 550 μm/year derived from tropical immersion data, supplemented by pitting analysis with Pitting Factor 3.5. Ultrasonic thickness gauging on a 500 mm grid was simulated for a 4,400 m² wetted hull area. Corrective renewal at critical loss (4,350 μm, 71% remaining thickness) was compared with a two-stage predictive strategy (interventions at 5.0 and 7.5 years, 20% thickness-loss trigger). Critical thickness was intercepted at t = 7.91 years under corrective strategy, requiring 414.4 tonnes effective steel renewal (530 standard plates) at ₦1.512 billion and 45 days downtime. The predictive strategy reduced steel renewal by 35-40%, cost to ₦1.20 billion (20.6% saving) and downtime to 28 days. Predictive corrosion modelling integrated with NDT enables timely, cost-effective hull renewal and is recommended for fleet operators in tropical marine environments.

Functional characterization of Detarium microcarpum seed proteins and polysaccharides as sustainable coagulant precursors for wastewater treatment

Wed, 07 Oct 2026 00:00:00 +0000

Chemical coagulants pose health and environmental concerns, driving search for plant-based alternatives for wastewater treatment. Detarium microcarpum seed, an underutilized leguminous plant in Nigeria, has potential as a natural coagulant but remains uncharacterized. This study characterized the physical properties, proximate composition and functional groups of Detarium microcarpum seed powder to assess its suitability as a bio-coagulant. Seeds were processed into powder and analyzed for yield, apparent density and proximate composition (moisture, ash, crude protein, crude fat, crude fibre, carbohydrate) using standard AOAC methods. Functional groups were identified by Fourier Transform Infrared (FTIR) spectroscopy in the range 4000–400 cm⁻¹. Powder yield was 28.31% with apparent density of 0.235 g/mL. Proximate analysis showed carbohydrate 56.76%, crude protein 19.77%, crude fat 10.53%, moisture 7.25%, ash 3.48% and crude fibre 2.20%. FTIR revealed nine bands, notably broad O–H/N–H stretching at 3272.6 cm⁻¹, aliphatic C–H at 2914.8 cm⁻¹, C=O/amide at 1636.3 cm⁻¹, and C–O/C–O–C stretching at 1148.0 and 1043.7 cm⁻¹, indicating hydroxyl-rich polysaccharides and proteinaceous matter. : The high carbohydrate and protein contents coupled with O–H, N–H, C=O and C–O functional groups confirm D. microcarpum seed possesses the chemical features required for charge neutralization and inter-particle bridging, supporting its potential as an eco-friendly bio-coagulant.

Enhancing CNG Cascade Refueling Efficiency for Heavy-Duty Transport Using Thermodynamic Management Techniques: Modeling and Optimization

Wed, 07 Oct 2026 00:00:00 +0000

Compressed Natural Gas refueling for heavy-duty transport suffers from severe under-filling due to temperature rise during fast-fill, which elevates cylinder pressure and triggers premature dispenser cut-off. This study enhances cascade refueling efficiency through thermodynamic management and optimization of reservoir volume distribution. A thermodynamic model was developed for a three-bank cascade system supplying a 350 L heavy-duty cylinder rated at 200 bar. The model integrated real gas behavior with compressibility factor, mass and energy conservation principles, and convective heat transfer between gas and cylinder wall. Reservoir volume ratio was optimized, and a temperature-compensated target pressure strategy was introduced to account for heat-induced pressure elevation and prevent early termination. The coupled differential equations were solved numerically using fourth-order Runge-Kutta method with 0.1 second time step. Results demonstrated that the optimal volume distribution of 0.20:0.30:0.50 for Low, Medium and High banks achieved superior performance. Final charged mass increased from 36.8 kg to 42.5 kg, fill ratio improved from 82.3% to 96.2%, representing 13.9% enhancement and 15.5% mass increase. Peak gas temperature reduced from 67 to 55.2 degrees Celsius, refueling time decreased from 340 to 300 seconds, and energy consumption reduced by 18.5% from 8.20 to 6.68 megajoules. Residual gas decreased to 12.5 kg, yielding an additional 43 km driving range. The framework improves filling completeness, maintains safety below ISO 11439 limit, and offers practical design guidelines for CNG stations in hot climates like Nigeria.