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Purnami
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Aerospace Engineering Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Control & Systems Engineering Electrical & Electronics Engineering Energy Materials Science & Nanotechnology Mechanical Engineering

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THE EFFECT OF AIR FLOW RATE ON THE CHARACTERISTICS OF PULVERIZED CATALYTIC COMBUSTION OF RICE HUSK WASTE BIOMASS Hamidi, Nurkholis; Yuliati, Lilis; Purnami; Maulana , Syahrizal
Jurnal Rekayasa Mesin Vol. 16 No. 2 (2025)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/jrm.v16i2.1856

Abstract

The purpose of this study was to determine the effect of airflow rate on the characteristics of catalytic combustion of pulverized rice husk biomass. Natural zeolite was used as the catalyst in this study. The combustion characteristics included the value of Initiation Temperature of Volatile Matter (ITVM), Initiation Temperature of Fixed Carbon (ITFC), peak of weight loss rate temperature (PT), Burning out Temperature (BT), mass reduction graph (TGA), mass reduction rate (DTG), heating value, and activation energy were measured. The sample used was 45-200 µm in size, and the percentage of catalyst was 7%. The research was carried out using 4 variations, including 2.9 ml/min, 5.8 ml/min, 9.0 ml/min, and 14.8 ml/min, each of which contains the same air composition, namely 80% nitrogen and 20% oxygen. The results showed that the greater the airflow contained in the pulverized biomass catalytic combustion process could increase the combustion characteristics including reducing the value of ITFC, PT, and BT. In addition, it also accelerates the rate of mass reduction and decreases its activation energy due to increasing pressure along with increasing temperature in the combustion chamber, besides that excess air also causes the combustion that occurs in more perfect combustion.
THERMODYNAMIC ANALYSIS OF ALKALINE ELECTROLYSIS UNDER VISIBLE LIGHT ILLUMINATION: COMPARATIVE ASSESSMENT OF GREEN AND BLUE LED EXPOSURE Santoso, Mardi; Ahmad, Anton Royanto; Sinurat, David Fernando; Hamidi, Nurkholis; Purnami
Jurnal Rekayasa Mesin Vol. 16 No. 3 (2025)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/

Abstract

This study explores the thermodynamic behavior of alkaline electrolysis under visible light illumination, focusing on the effects of green and blue wavelengths in the absence of chemical additives. Through a series of controlled experiments, temperature evolution, energy input, and thermal efficiency were analyzed over a 20-minute electrolysis period. Results show that both green and blue light enhance the system's thermal response compared to dark (control) conditions, with blue light achieving the highest temperature rise and energy conversion efficiency. Arrhenius analysis revealed a clear temperature dependence of the rate constant, and strong correlations were observed between temperature rise (ΔT), heat energy (Q), and system efficiency. These findings suggest that visible light particularly blue light can significantly improve the thermal dynamics of electrolysis systems, paving the way for low-cost, passive solar-assisted hydrogen production.
Probabilistic Performance Prediction of a Hydrogen-Converted SI Engine Using a Markov-Chain-Wiebe Framework Purnami; Nugroho, Willy Satrio; Yuliati, Lilis; Alamsyah, Fikrul Akbar; Wardana, ING; Wahid, Abdul Mudjib Sulaiman
Automotive Experiences Vol. 9 No. 1 (2026): Issue in Progress
Publisher : Universitas Muhammadiyah Magelang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31603/ae.15544

Abstract

This study employs a novel Markov-chain modeling framework to analyze the combustion-performance interaction in a hydrogen-fueled spark-ignition engine. The methodology integrates a Wiebe heat-release model within a Markov-chain state-transition framework, where each discrete engine state defines combustion parameters and probabilistic transitions capture cycle-to-cycle variability. Results demonstrate that engine behavior is dominantly governed by combustion phasing, with spark timing exerting primary control over torque, efficiency, and brake-specific fuel consumption (BSFC). Sensitivity analysis confirms spark timing produces the steepest performance gradients, while ignition voltage offers secondary benefits and engine speed exhibits minimal influence. The model reveals a highly nonlinear torque response to spark advance, characterized by a rapid rise culminating in a narrow maximum brake torque (MBT) plateau at 8°–10° BTDC, corresponding to a distinct BSFC minimum. Significant data scatter underscores the stochastic nature of hydrogen combustion, arising from multidomain interactions between air-fuel ratio, ignition strength, and phasing. The Markov-chain approach successfully captures this coupled deterministic-probabilistic behavior, highlighting the critical need for precise spark-timing control to optimize performance in hydrogen applications.
Co-Authors Anton Royanto Ahmad Fikrul Akbar Alamsyah ING Wardana Lilis Yuliati Mardi Santoso Maulana , Syahrizal Nurkholis Hamidi Sinurat, David Fernando Wahid, Abdul Mudjib Sulaiman Willy Satrio Nugroho