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Performance of Porous-Venturi Microbubble Generator for Aeration Process Afisna, Lathifa Putri; Juwana, Wibawa Endra; Indarto, Indarto; Deendarlianto, Deendarlianto; Nugroho, Fellando Martino
Journal of Energy, Mechanical, Material and Manufacturing Engineering Vol 2, No 2 (2017)
Publisher : University of Muhammadiyah Malang

Qualified and preserved water is declining due to metal, waste, and hazardous chemicals contamination. Demand on fresh water raises and leads to the efforts on processing waste water with effective and efficient technology. Microbubble generator technology developed lately to result dissolved oxygen for raising microorganisms to decompose waste in waste water. This research used porous-ventury microbubble generator with 30Â° inlet angle and 20Â° outlet angle, placed in the center of 280 cm x 60 cm x 40 cm aquarium for experiment. This research aimed to find out bubble distribution and microbubble generator (MBG) performance. Measurement on bubble distribution conducted using Phantom Control Camera. Obtained data analyzed using MATLAB R2016a, while MBG performance measured using pressure transducer. Analysis conducted on variations of gas debit (0,1 lpm; 0,4 lpm., and 1 lpm) and water debit (30- 80 lpm) effects toward performance parameters, such as hydraulic power (Lw) and bubble generating efficiency (Î·B). Results show that the greatest microbubblesâ diameter is 150- 500 Î¼m, hydraulic power (Lw) increases with the inclining water debit (QL), effect of gas debit variation exert low effect towards Lw, and declining number of bubble generating efficiency (Î·B) parameter with the inclining number of the water debit (QL).

STUDI EKSPERIMENTAL PENINGKATAN PERPINDAHAN PANAS ALIRAN TURBULEN PADA PENUKAR KALOR PIPA KONSENTRIK DENGAN PERFORATED TWISTED TAPE INSERT WITH PARALLEL WINGS Yaningsih, Indri; Istanto, Tri; Juwana, Wibawa Endra
ROTASI Vol 17, No 3 (2015): VOLUME 17, NOMOR 3, JULI 2015
Publisher : Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro

Heat transfer, flow friction and thermal performance factor characteristics in a concentric pipe heat exchanger fitted perforated twisted tape insert with parallel wings (PTPW), using water as working fluid are investigated experimentally. The design of PTPW involves the following concepts: (1) wings induce an extra turbulence near tube wall and thus efficiently disrupt a thermal boundary layer (2) holes existing along a core tube, diminish pressure loss within the tube. The experiments are conducted using the PTPW with the three wing depth ratio (w/W = 0.16, 0.24 and 0.32) and constant the hole diameter ratio (d/W) of 0.24 over a Reynolds number range of 5800â€“18,500. A typical twisted tape insert (TT) was also tested for a comparison. The results show that both mean Nusselt number and mean friction factor associated by all twisted tape are consistently higher than those without twisted tape (plain tube). It is also found that Nusselt number, friction factor and thermal performance factor increase with increasing wing depth ratio. Over the range considered, Nusselt number and friction factor in a concentric pipe heat exchanger with the PTPW are, respectively, 1.14â€“1.42 and 1.12â€“1.40 times of those in the tube with typical twisted tape (TT).

SIMULATION-BASED ASSESSMENT KINERJA TERMAL PADA CONCENTRIC TUBE HEAT EXCHANGER Kristiawan, Budi; Wijayanta, Agung Tri; Juwana, Wibawa Endra; Rachmanto, Rendy Adhi; Enoki, Koji; Prasojo, Arfi Singgih
Jurnal Rekayasa Mesin Vol. 14 No. 3 (2023)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/jrm.v14i3.1372

The double-pipe heat exchanger is one of the most popular heat exchanger devices. In this study, the concentric tube heat exchanger as the double pipe heat exchanger device was simulated with ANSYS code FLUENT. The simulation was done by based on the Reynolds number variation from 400010.000 using the method of co-current and counter flow. The hydrodynamic and thermal simulation results agree with the empirical correlation of the Pethukov and Dittus-Bolter equations, respectively. The friction factors of the water base fluid and nanofluid f TiO2/water f (0.1 vol.%) do not result in a significant difference in the turbulent flow regime for both co-current and counter flow. The thermal performance of TiO2/water (0.1% vol) nanofluid as indicated by the value of the heat transfer coefficient results in an increase of 6.9% for counter low flow and 6.0% for co-current flow. Meanwhile, the direction of fluid flow in the heat exchanger does not have a significant effect on its thermal performance.

Enhancing Biogas Production through the Co-Digestion of Indigofera and Cow Manure for Electricity Generation Suyitno, Suyitno; Juwana, Wibawa Endra; Muqoffa, Mohamad
Journal of Engineering and Technological Sciences Vol. 57 No. 3 (2025): Vol. 57 No. 3 (2025): June
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.3.1

The research examines the augmentation of biogas generation through the co-digestion of Indigofera tinctoria waste and cow manure, emphasising the optimization of parameters for enhanced efficiency. Anaerobic digestion presents potential for sustainable waste management and renewable energy generation. The initial discussion underscores the significance of Indigofera tinctoria, alongside challenges in managing agricultural and organic waste. The methodology encompasses substrate preparation, reactor design, and biogas utilization for electricity generation. Results indicate that substrate feeding rates and pH levels significantly influence biogas production, with optimal efficiency observed when pH is maintained between 6 and 7. Feeding rates are identified as a critical factor, highlighting the necessity for precise optimization. Additionally, managing hydrogen sulfide content is vital to mitigate corrosion risks, which can be addressed through adjustments to substrate composition. An interaction analysis between substrate feeding rates and pH revealed no significant combined effects, emphasizing the importance of understanding individual parameter dynamics to maximize production efficiency. Optimal load conditions were identified, with diminishing returns observed beyond a specific threshold. This study provides valuable insights into improving biogas production efficiency from Indigofera tinctoria waste and cow manure. Key recommendations include the optimization of substrate composition and stringent pH regulation to promote sustainable biogas production practices. Future research is encouraged to further refine biogas technology and advance its application in renewable energy systems.

Effect of Freshwater and Seawater Immersion on Mechanical Properties and Pre-Immersion Magnetic Response of Silicone Rubber–Magnetite Composite Magnets Wibowo, Wibowo; Santoso, Nehemia Herbert; Ramadhan, Brilliano Wahyu; Juwana, Wibawa Endra; Kaavessina, Mujtahid
Jurnal Ilmu Fisika Vol 18 No 1 (2026): March 2026
Publisher : Jurusan Fisika FMIPA Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jif.18.1.25-34.2026

Magnetite (Fe₃O₄) and RTV 48 silicone rubber-based magnetic composites have potential for outdoor applications due to their flexible and tunable magnetic properties. This study investigates the effect of immersion for 14 days in fresh water and seawater on its mechanical, magnetic, and thermal properties. Specimens were made by mixing 70 wt% Fe₃O₄ powder into RTV 48 matrix, then tested for hardness using Shore A durometer, magnetic properties using Vibrating Sample Magnetometer (VSM), and thermal stability using Thermogravimetric Analysis (TGA). Results showed a decrease in surface hardness due to matrix degradation by water penetration. The magnetic properties continued to exhibit soft magnetic characteristics with low coercivity and remanence. TGA analysis revealed changes in thermal degradation patterns, signaling chemical interactions between the material and the wet environment. These findings suggest that exposure to water can affect the long-term performance of Fe₃O₄-RTV 48 composites, making moisture resistance an important aspect for their outdoor applications.

SIMULATION-BASED ASSESSMENT KINERJA TERMAL PADA CONCENTRIC TUBE HEAT EXCHANGER Kristiawan, Budi; Wijayanta, Agung Tri; Juwana, Wibawa Endra; Rachmanto, Rendy Adhi; Enoki, Koji; Prasojo, Arfi Singgih
Jurnal Rekayasa Mesin Vol. 14 No. 3 (2023)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/jrm.v14i3.1372

The double-pipe heat exchanger is one of the most popular heat exchanger devices. In this study, the concentric tube heat exchanger as the double pipe heat exchanger device was simulated with ANSYS code FLUENT. The simulation was done by based on the Reynolds number variation from 400010.000 using the method of co-current and counter flow. The hydrodynamic and thermal simulation results agree with the empirical correlation of the Pethukov and Dittus-Bolter equations, respectively. The friction factors of the water base fluid and nanofluid f TiO2/water f (0.1 vol.%) do not result in a significant difference in the turbulent flow regime for both co-current and counter flow. The thermal performance of TiO2/water (0.1% vol) nanofluid as indicated by the value of the heat transfer coefficient results in an increase of 6.9% for counter low flow and 6.0% for co-current flow. Meanwhile, the direction of fluid flow in the heat exchanger does not have a significant effect on its thermal performance.

Design, Production Cost, and Air Flow Distribution of Biomass Pellet Furnace Sutanto, Heru; Suyitno, Suyitno; Juwana, Wibawa Endra; Nurrohim, Tito Gusti
Mekanika: Majalah Ilmiah Mekanika Vol 20, No 2 (2021): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v20i2.49232

Biomass attracts a great deal of attention because it is converted into green fuels in the form of pellets. The furnace is needed to burn pellets to generate up to 300 kW of heat. In addition to meeting the heat capacity needs of small and medium-sized industries, furnaces must also be competitive in terms of price. Therefore, the purpose of this study is to obtain details of the cost of manufacturing the furnace and the airflow model that occurs in the furnace. This study employs a forward and reverses engineering approach, beginning with determining load and capacity, drawing, determining the bill of materials and manufacturing, numerical modeling of airflow with ANSYS FLUENT, fabrication, and final testing. The outcome revealed that the furnace's production cost included manufacturing costs, assembly costs, machining, and repair costs. The findings revealed that the critical portion of the cost of the furnace was the material cost of 77%. The simulation findings showed that the total pressure difference of up to 850 Pa had to be resolved by air-supplying blowers. The gas velocity ranged from 2 to 10 m/s and increased significantly near the exit to 42 m/s.

Experimental Test of Ignition Timing with Programable CDI on Performance Single Cylinder Otto Engine Rachmanto, Rendy Adhi; Wijayanto, Martinus Darmawan Bagas; Juwana, Wibawa Endra; Kataraki, Pramodkumar Siddappa
Mekanika: Majalah Ilmiah Mekanika Vol 21, No 2 (2022): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v21i2.58951

Ignition timing is sparking from the spark plug based on the ignition angle during the compression stroke in the combustion chamber relative to the piston position and the crankshaft angular speed. Adjusting the ignition angle is one method to optimize the combustion process in the engine. An optimal combustion process can improve engine performance and reduce fuel consumption. This study investigates optimal data from ignition angle changes using a programmable Capacitive Discharge Ignition (CDI). The test was performed on a single-cylinder four-stroke Otto engine with standard ignition angle variations, +3°, +6°, and +9° before Top Dead Centre (TDC). The test results show that torque and power have increased while brake-specific fuel consumption has decreased. Optimal data acquisition at ignition angle of +9° with peak torque value of 6.91 Nm and peak power value of 4.80 kW, while the lowest value of specific fuel consumption is 0.234 kg/kWh, and the highest value of thermal efficiency is 36%. From this study, it was concluded that the ignition timing could affect the engine performance.

Experimental Study Influences Changes In Compression Ratio To Performance Of Single Cylinder Otto Engine Juwana, Wibawa Endra; Rachmanto, Rendy Adhi; Wiyono, Mugi; Istanto, Iwan
Mekanika: Majalah Ilmiah Mekanika Vol 21, No 2 (2022): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v21i2.59487

Increasing the compression ratio is an attempt to increase the efficiency and performance of the engine. The purpose of the study was to analyze the effect of changes in the compression ratio on engine performance. Tests using a single-cylinder Otto engine by comparing the performance of an enlarged compression ratio of 9.7:1 and 10.4:1 with a standard compression ratio of 9.0:1. The result of the research is that the compression ratio of 9.7:1 produces a peak torque of 7.51 Nm at 6000 rpm, a peak power of 5.30 kW at 8000 rpm, and the lowest Brake-Specific Fuel Consumption (BSFC) is 0.146 kg/kWh at 6000 rpm. Torque and power increased by 0.09 Nm and 0.28 kW, and Brake-Specific Fuel Consumption (BSFC) decreased by 0.018 kg/kWh compared to the standard compression ratio of 9.0:1. Using a compression ratio of 10.4:1 produces a peak torque of 7.69 Nm at 6000 rpm, a peak power of 5.38 kW at 8000 rpm, and the lowest Brake-Specific Fuel Consumption (BSFC) is 0.116 kg/kWh at 6000 rpm. Torque and power increased by 0.27 Nm and 0.36 kW, and Brake-Specific Fuel Consumption (BSFC) decreased by 0.030 kg/kWh compared to the standard compression ratio of 9.0:1.

Implementation of Solar-Powered Water Purification Technology to Enhance Quality of Life in Rural Areas Suyitno, Suyitno; Arifin, Zainal; Tjahyana, Dominicus Danardono Dwi Prija; Juwana, Wibawa Endra; Rachmanto, Rendy Adhi; Yaningsih, Indri
SEMAR (Jurnal Ilmu Pengetahuan, Teknologi, dan Seni bagi Masyarakat) Vol 13, No 2 (2024): November
Publisher : LPPM UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/semar.v13i2.90334

This study presents the development and implementation of a solar-powered reverse osmosis (RO) water purification system at Pondok Pesantren Tijarotul Qur’aniyah, Sub-district of Bulu, District of Sukoharjo, Indonesia. The project aimed to provide a sustainable solution to the urgent need for clean drinking water in the community. The implementation process was divided into four main phases: comprehensive survey and needs analysis, prototype development and testing, system implementation, and long-term monitoring and evaluation. The initial survey identified significant issues with water quality and accessibility, leading to the design of a tailored RO system powered by solar energy. The prototype was rigorously tested and adjusted based on user feedback to ensure it met community requirements. The system was implemented on a small scale, involving the construction of necessary infrastructure and integration of solar panels for reliable power. Post-implementation water quality tests showed substantial improvements in key parameters. Results included a pH level of 7.20, hardness (CaCO₃) at 252.87 mg/L, total dissolved solids (TDS) at 0.023 mg/L, and iron (Fe) at 0.2639 mg/L. Chlorine and chromium levels were 0.00 mg/L, manganese (Mn) was 0.1001 mg/L, ammonia (NH₃) was 1.14 mg/L, and sulfate (SO₄) was 11.26 mg/L. All parameters met the quality standards set by the Indonesian Ministry of Health and Government Regulation on Water Quality Management. Continuous monitoring and educational programs were incorporated to ensure local engagement and long-term sustainability. This study demonstrates that the solar-powered RO system effectively meets the community’s need for clean water and offers a scalable model for similar regions, highlighting the potential of combining renewable energy with advanced water purification technologies. Keywords: Water Purification, Reverse Osmosis, Solar Energy, Water Quality, Sustainability

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