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All Journal Rotasi Rekayasa Mesin Journal of Energy, Mechanical, Material and Manufacturing Engineering Jurnal Ilmu Fisika Journal of Engineering and Technological Sciences
Wibawa Endra Juwana, Wibawa Endra
Jurusan Teknik Mesin, Fakultas Teknik, Universitas Sebelas Maret
Aerospace Engineering Astronomy Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Earth & Planetary Sciences Electrical & Electronics Engineering Materials Science & Nanotechnology Mechanical Engineering Physics

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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

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (698.696 KB) | DOI: 10.22219/jemmme.v2i2.5054

Abstract

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 30° inlet angle and 20° 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 (ηB). Results show that the greatest microbubbles’ diameter is 150- 500 μm, 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 (ηB) 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

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (463.21 KB) | DOI: 10.14710/rotasi.17.3.120-129

Abstract

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 5800–18,500. 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, 1.14–1.42 and 1.12–1.40 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

Abstract

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

Abstract

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 (Forthcoming Issue)
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

Abstract

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.
Co-Authors Afisna, Lathifa Putri Budi Kristiawan, Budi Deendarlianto Enoki, Koji Indarto Indarto Indri Yaningsih Mohamad Muqoffa Mujtahid Kaavessina, Mujtahid Nugroho, Fellando Martino Prasojo, Arfi Singgih Rachmanto, Rendy Adhi Ramadhan, Brilliano Wahyu Santoso, Nehemia Herbert Suyitno Suyitno Tri Istanto Ubaidillah Ubaidillah Wibowo Wibowo Wijayanta, Agung Tri