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Tanzir Masykar
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Vocatech : Vocational Education and Technology Journal
Published by Akademi Komunitas Negeri Aceh Barat
ISSN : 26864770     EISSN : 27165183     DOI : DOI: https://doi.org/10.38038/vocatech.v2i1
Core Subject : Science, Education, Engineering,
Civil Engineering, Building, Construction & Architecture Computer Science & IT Education Electrical & Electronics Engineering Mechanical Engineering
1. Vocational Studies 2. Civil Engineering 3. Electrical Engineering 4. Mechanical Engineering 5. Classroom Instruction in Vocational Context 6. English for Vocational Purposes 7. Innovation in Vocational Education
Arjuna Subject : Teknik (semua kategori) - Teknik (Lain-Lain)
Articles 102 Documents
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Analysis of Thermal Efficiency of the Honda GK5 Engine Fueled with Young Coconut Waste Bioethanol Using a Thermodynamic Approach Wahyudi, Retno; Ibrahim, Fauzi; Sembiring, Alexander; Apriyanto, Agus; Murti, Adam Wisnu; Putri, Novia Utami
VOCATECH: Vocational Education and Technology Journal Vol 7, No 1 (2025): August
Publisher : Akademi Komunitas Negeri Aceh Barat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.38038/vocatech.v7i1.214

Abstract

The global energy crisis and increasing awareness of the negative environmental impacts of fossil fuels have driven the development of sustainable alternative energy sources. One promising renewable fuel is bioethanol, especially when produced from agricultural waste such as young coconut waste. This study aims to evaluate the effect of using bioethanol derived from young coconut waste on the thermal efficiency of the Honda GK5 engine through thermodynamic analysis based on the Otto cycle model and verification using experimental data. The research method includes laboratory testing of the Honda GK5 engine with variations in fuel mixtures: E0, E10, E20, and E30. The test results show a significant increase in thermal efficiency up to the E20 mixture, with an experimental efficiency of 31.8% and a theoretical efficiency of 32.0%. This improvement is attributed to the high octane number of bioethanol, which supports more complete combustion. However, at the E30 mixture, a decrease in efficiency is observed due to the lower heating value of bioethanol. The Otto cycle model successfully represents the trend of thermal efficiency with an average deviation of 1–1.5% compared to experimental results. Therefore, bioethanol from young coconut waste proves not only to be environmentally friendly but also capable of enhancing engine energy performance optimally without requiring significant modifications.
Optimisasi Desain Heat Exchanger Shell dan Tube Menggunakan Helical Baffles dan Twisted Tape Inserts Sebagai Teknologi untuk Meningkatkan Heat Transfer Coefficient Syafi'i, Ahmad; WimbangWicaksono, Muhammad Jaka; Darmoyono, Aditya Gautama; Lubis, Eka Mutia; Oktani, Dessy; Kamarudin, Kamarudin; Mahdaliza, Rahmi; Gusnam, Mu'thiana; Biyanto, Totok Ruki; Utami, Intan Tri
VOCATECH: Vocational Education and Technology Journal Vol 7, No 1 (2025): August
Publisher : Akademi Komunitas Negeri Aceh Barat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.38038/vocatech.v7i1.217

Abstract

Abstract Heat exchanger is a device used to transfer thermal energy between two or more fluids at different temperatures. This study aims to develop an efficient shell and tube heat exchanger design that is accompanied by an increase in the overall heat transfer coefficient on the shell and tube sides simultaneously. This study focuses on the impact of using helical baffles and twisted tape inserts technology on the total heat transfer coefficient (U) and pressure drop (ΔP). This study analyzes the effect of employing helical baffles on the shell side and twisted tape inserts on the tube side, with optimization using the Genetic Algorithm (GA) method. The independent variables considered include the helical baffles angle (β), the spacing between baffles (Lbc), the thickness of the twisted tape (δ), and the half-pitch of the twisted tape (H). The optimization objective function for both the shell side and tube side is to maximize the overall heat transfer coefficient, while the restriction is that the pressure drop must not surpass the starting design data value. In this study, the E-1-06 heat exchanger was successfully modeled. The modeling data showed only slight differences between the modeling results and the initial data sheet. The deviation value of the overrall heat transfer coefficient (U) = 0.06%, ∆Ps = 0.00%, and ∆Pt = 0.06%. Optimization of the E-1-06 heat exchanger was also successful. Optimization in this study was able to increase the U value by 3.97%, while the ∆Ps value decreased by -2.01% and ∆Pt by -19.11%. The findings indicate that the modified design is capable of enhancing thermal performance without compromising hydraulic efficiency, thereby demonstrating its potential for application in energy processing systems and industrial cooling.AbstrakHeat exchanger adalah perangkat yang digunakan untuk menyalurkan energi termal antara dua atau lebih fluida pada suhu yang berbeda-beda. Penelitian ini bertujuan untuk mengembangkan desain heat exchanger shell dan tube yang efesien yang disertai dengan peningkatan koefisien perpindahan kalor secara keseluruhan pada sisi shell dan tube secara bersamaan. Penelitian ini berfokus pada dampak penggunaan teknologi helical baffles dan twisted tape insert pada koefisien perpindahan kalor total (U) dan penurunan tekanan/ Pressure drop (ΔP). Pada awalnya heat exchanger ini menggunakan teknologi segmental baffle pada sisi shell dan plain tube pada sisi tube, kemudian desainnya dimodifikasi dengan teknologi yang berbeda, desain pada sisi shell digunakan teknologi helical baffle sedangkan pada sisi tube digunakan teknologi twisted tape. Metode optimisasi yang digunakan adalah Genetic Algoritm (GA). Variabel bebas yang digunakan untuk melakukan optimisasi pada sisi shell adalah sudut helical baffle (ß) dan jarak antar baffle (Lbc) yang ada dalam heat exchanger. Sedangkan variabel bebas yang digunakan pada sisi tube adalah thickness of twisted tape (?), dan half pitch of twisted tape (H). Fungsi tujuan (objective function) optimisasi pada sisi shell dan sisi tube yaitu koefisien perpindahan panas secara keseluruhan (overrall heat transfer coefficient) yang maksimal dan constraint pada optimisasi ini yaitu penurunan tekanan (pressure drop) yang besar nilainya tidak boleh melampaui nilai dari data awal design. Pada penelitian ini heat exchanger E-1-06 berhasil dimodelkan. Data permodelan menunjukkan hanya sedikit perbedaan antara hasil permodelan dengan data sheet awal. Nilai deviasi overrall heat transfer coefficient (U) = 0.06%, ∆Ps=0.00%, dan ∆Pt= 0.06%. Optimisasi Heat exchanger E-1-06 juga berhasil dilakukan. Optimisasi pada penelitian ini mampu menaikan nilai U sebesar 3.97%, sementara nilai ∆Ps mengalami penurunan sebesar -2.01% dan ∆Pt sebesar -19.11%.

Page 11 of 11 | Total Record : 102

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