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Mira Lestira Hariani
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INDONESIA
Journal of Green Science and Technology
Published by Universitas Swadaya Gunung Jati
ISSN : 25981277     EISSN : 26213966     DOI : https://doi.org/10.33603/jgst.v9i1
Core Subject : Engineering,
Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Electrical & Electronics Engineering Engineering Transportation
Journal of Green Science and Technology (JGST) published since 2017 by Faculty of Engineering Universitas Swadaya Gunung Jati Cirebon, Indonesia with p-ISSN 2598-1277 and e-ISSN 2621-3966. JGST publishes twice a year in March and September. Publications before 2023 can be seen here. Journal of Green Science and Technology (JGST) has been accredited by National Journal Accreditation (ARJUNA) Managed by Ministry of Research, Technology, and Higher Education, Republic Indonesia since year 2022 to 2022 according to the decree No. 230/E/KPT/2022. Journal of Green Science and Technology (JGST) accepts and publishes multidisciplinary research and critical review of issues that contains of all scientific works related to the field of following Sciences Engineering: - Civil Engineering - Architectural Engineering - Environmental Engineering - Chemical Engineering - Mechanical Engineering - Electrical Engineering - Industrial Engineering - Informatics Engineering, etc. All manuscripts must be written in English.
Arjuna Subject : Teknik (semua kategori) - Teknik (Lain-Lain)
Articles 142 Documents
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Natural Based Carbon Briquettes: The Effect of Coffee Ground Carbonization Temperatures as Renewable Energy Alternative Ramadhani, Fauziah; Sa’diyyah, Ghina Nabila Nur; Putri, Salsabila Azaliyah; Anggraeni, Danisa Dwi; Adhitasari, Alfiana; Saripudin, Saripudin
Journal of Green Science and Technology Vol 9 No 3 (2025): Journal of Green Science and Technology Vol. 9 No. 3 December 2025 Special Editio
Publisher : Faculty of Engineering, Universitas Swadaya Gunung Jati

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33603/jgst.v9i3.10677

Abstract

Coffee consumption in Indonesia has been increasing over time. As a result of the high consumption and production, coffee waste often ends up in landfills. One potential solution to this problem is converting coffee waste into reusable products. Coffee grounds waste can be utilized as renewable energy in the form of briquettes. In this research, coffee grounds are used as briquette material. Briquettes are made by the carbonization method. Temperature plays a crucial role in determining the quality of briquette. This study aims to identify the optimum carbonization temperature, with variations of 350°C, 400°C, and 450°C. Each briquette sample was analyzed according to the Indonesian National Standard SNI 01-6235-2000. The results show that all carbonization temperatures produced briquettes with high calorific values (>5000 cal/g), that is 6981 cal/g at 350°C, 7037 cal/g at 400°C, and 7043 cal/g at 450°C. However, the resulting briquettes did not meet the standard criteria for density, fixed carbon, and volatile matter.
Optimization Of Mixing Chamber Design on Steam Ejector at Geothermal Power Plant Based on CFD Simulation Rusdan, Sendi Salman; Suprianti, Yanti
Journal of Green Science and Technology Vol 9 No 3 (2025): Journal of Green Science and Technology Vol. 9 No. 3 December 2025 Special Editio
Publisher : Faculty of Engineering, Universitas Swadaya Gunung Jati

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33603/jgst.v9i3.10689

Abstract

The initial generation capacity of 30 MW at the Geothermal Power Plant (GPP) decreased to 11.88 MW due to reduced steam supply from production wells. This mismatch between the original system design and current operating conditions affected components such as the steam ejector, which experienced a reduction in motive steam flow from 1.96 kg/s to 1.66 kg/s. As a result, the mixing chamber became inefficient in entraining flow of non- condensable gases (NCG), causing suboptimal pressure ratios (P3/P5), turbulence, and backflow. This study aims to redesign the mixing chamber of the steam ejector to enhance the extraction NCG. Using compressible flow theory and CFD simulation with Ansys Fluent 2025R1, the redesigned geometry improved the entrainment ratio from 0.27 to 0.31 and increased the NCG suction rate from 0.45 kg/s to 0.52 kg/s. The pressure ratio P3/P5 rose from 0.04 to 0.07, approaching optimal conditions. Further analysis revealed that under increased motive flow (1.687 kg/s), the ejector achieved an entrainment ratio of 0.32, and under lowered condenser pressure (8.1 kPa), the entrainment reached 0.34. These two optimal conditions demonstrate the redesigned chamber’s adaptability under varied operational scenarios. The performance improvement contributed to an additional power output of 41.68 kWh, approaching the plant’s installed capacity and improving system reliability. From economic perspective, the optimization is also feasible, yielding a net present value (NPV) of Rp6.46 million and demonstrating high profitability and practical applicability.

Page 15 of 15 | Total Record : 142

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