6 research outputs found
EVALUASI DAMPAK SISTEM CONTINUOUS BLOWDOWN BOILER DARI SEGI TEKNIS DAN EKONOMI DI LINGKUNGAN PT PLN SEKTOR PEMBANGKITAN KERAMASAN
No full textBlowdown merupakan suatu operasi pemeliharaan yang dilakukan pada boiler untuk membuang semua kotoran berupa campuran air dengan zat kimia dan partikel di dalam air yang bisa menimbulkan kerak/lumpur, tetapi bila berlebihan bisa menimbulkan kerugian termal. Oleh karena itu, jumlah pengoperasian blowdown perlu diantisipasi guna mengurangi kerugian termal, khususnya pada kinerja boiler. Berdasarkan hasil analisis dan perhitungan, sistem continuous blowdown yang ada sekarang ini pada PLTU Unit 2 PT PLN Sektor Pembangkitan Keramasan, dari segi teknis telah terjadi penurunan efisiensi boiler sekitar 2,2 %, dengan rata–rata efisiensi boiler sebesar 60,43 %. Kerugian lain akibat blowdown dalam satu hari yaitu kehilangan sejumlah panas sebesar 1200,43MJ/jam dan bahan bakar rata-rata sebesar 22,61 kg/jam. Dengan biaya produksi sebesar $ 4,85,-/MMBTU, bila diakumulasikan dalam satu bulan atau lebih, dari segi ekonomi sistem blowdown yang ada sekarang ini, menimbulkan kerugian ekonomi sebesar Rp. 40 juta/bulan. Jika pada saat sekarang ini diterapkan sistem continuous blowdown sebelum tahun 1995, dapat diketahui bahwa penghematan biaya bahan bakar dapat mencapai 28,5 juta/bulan dengan pemanfaatan panas air blowdown mencapai 72,97 %
Effects of Battery State of Charge on Fuel Economy of Hybrid Electric Vehicles: An Analysis Using the UN ECE R101 Method
No full textIndonesia is currently embracing electric vehicle technology for widespread use and mass production, with hybrid vehicles serving as a crucial intermediary in the transition towards full electric vehicle adoption, as outlined in the roadmap established by the Indonesian Government through the Ministry of Industry. Hybrid vehicles integrate an internal combustion engine and an electric motor as the powertrain system, enabling the charging of the battery through the combustion engine while also serving as the primary mover, with charging and discharging cycles contingent upon the vehicle's operational conditions. This research investigates the impact of battery conditions on the fuel economy of two hybrid vehicles during a UN ECE R101 test cycle. This research focusing on two specific battery conditions: a state of charge (SoC) of 50% and 100%. Remarkably, the results indicate that vehicles with a SoC of 100% exhibit a noteworthy enhancement in fuel economy, achieving an improvement of up to 16% compared to those with a SoC of 50%. These findings shed light on the significant role that battery conditions play in optimizing fuel efficiency within hybrid vehicles, ultimately contributing to the ongoing advancements in sustainable transportation and the realization of the Indonesian Government's electric vehicle roadmap
Numerical Modelling Co-Firing Combustion in the Existing Coal-Fired Power Plant: Case Study in Paiton 9 Power Plant
No full textBiomass cofiring, a technique that involves combusting biomass alongside fossil fuels in power generation, presents a promising pathway toward achieving net-zero emissions. As an alternative solution, biomass co-firing is planned to be implemented to reduce emissions of the existing coal-fired power plant (CFPP) in Indonesia. This paper presents a numerical study using the computational fluid dynamics (CFD) approach. A Paiton 9’s power plant was selected as the object domain, and five cases related to fuel composition were prepared i.e., 100% coal, 100% biomass and three cases of mixture ratio of coal and biomass. Sawdust, a source of biomass, is mixed with coal and varies in ratios namely 5%, 10% and 15%. The combination of the species transport model, realizable k-ε turbulence model, combustion model and dual heat exchanger model was used to analyze combustion characteristics such as the average temperature profiles, velocity profiles and mass fractions of pollutants, including NOx, CO2, and HCn. The results report the highest average furnace gas exit temperature is about 1300oC by using 100% coal. By increasing the ratio of sawdust in the coal, the furnace gas exit temperature reduces close to recommended optimum range of gas exit temperature. Furthermore, the NOx and CO2 emissions trend to decline due to effects of decreasing furnace temperature and low carbon levels in fuel. Hence, selecting an appropriate sawdust ratio in the coal and fuel composition is the key point to maintaining the stability of furnace exit gas temperature. Later, observations of co-firing combustion are required to ensure the accuracy of the model in this study
Numerical Investigation of Heat Production in the Two-Wheeler Electric Vehicle Battery via Torque Load Variation Test
No full textExperimental studies were conducted to investigate the effect of varying torque loads on the temperature distribution on the surface of lithium-ion batteries (72 volts–20 Ah) in real commercial two-wheeler electric vehicles as part of our previous research. An electric vehicle engine was installed in a dyno testing laboratory and used as the main load for the battery. Ambient temperature and relative humidity were controlled using an air conditioning system. The test results are presented as surface temperature distributions on each side of the battery at various torque loads. The highest temperature on the battery’s surface was found to be approximately 40 °C at a torque load of 100%. Unfortunately, the heat generated by the battery during testing could not be measured for further research. This paper presents a numerical study of battery heat generation at 100% torque load using Ansys Fluent 2020 R1©. This tool is employed to calculate the heat flux from the battery surface to the ambient air. The CFD tool was initially validated against available experimental data and commonly used correlations for natural convection along a vertically heated wall. Good agreements between the current predictions and experimental data were observed for laminar flow regimes. Convective heat transfer between the battery surface and ambient air was simulated. The results indicate that the commonly used heat transfer correlation for vertical plates accurately predicts the heat transfer rate on the battery surface, and it was found that the heat generation rate is 1199 W/m3
Experimental study of flow characteristics in hydrodynamic and aerodynamic L-shaped and U-shaped oscillating water column chambers
No full textRecent research on oscillating water column (OWC) systems has primarily focused on chamber design, which serves as the main absorber for capturing wave energy. Geometric designs of L-shaped and U-shaped OWC chambers have been commissioned and constructed. However, studies addressing the comparative performance and optimization of L-shaped and U-shaped chambers remain limited. This study investigates the hydrodynamic and aerodynamic performance of OWC devices featuring innovatively designed L-shaped and U-shaped chambers, with adjustments made in laboratory settings. Experiments were conducted in a 2D wave flume laboratory equipped with a shallow-water piston-type wave generator. Four variations of wave heights, ranging from 0.0625 m to 0.25 m, and wave periods, from 1.77 s to 3.18 s, were tested, corresponding to sea conditions in the Arafura and Banda Seas, Indonesia. Key parameters, including free surface elevation, airflow velocity, and pressure differences, were measured to evaluate chamber performance. The results indicate that the geometry and design of OWC chambers significantly influence their ability to convert wave energy. The L-shaped chamber consistently outperformed the U-shaped chamber, achieving an optimal power output of 171 W under specific wave conditions, effectively converting incident wave energy into pneumatic power. In contrast, the U-shaped chamber exhibited lower efficiency due to suboptimal wave oscillations within the chamber. These findings highlight the advantages of the L-shaped chamber, particularly its superior ability to generate substantial free surface oscillations, velocity, and pressure in the chamber and airflow in the turbine duct. This study provides valuable insights into the optimization of OWC chamber designs, emphasizing the critical role of geometric configurations in enhancing energy capture efficiency under realistic sea conditions
Biomass fuel quality improvement using hydrogen peroxide and demineralized water pre-treatment and torrefaction
No full textBiomass is a neutral carbon-potential solid fuel and, hence, it is environmentally friendly. However, biomass is characteristically hygroscopic, has a high-moisture content, a low calorific value, low resistance to biological degradation, and several storage issues. Therefore, torrefaction has received much attention in the last decade from researchers to overcome the problem because it can potentially improve the quality of biomass for fuel. This study examined the biomass pre-treatment technique and torrefaction for producing high-quality solid fuel. The empty oil palm bunches (EFBs) were soaked in 10% wt, 18% wt, and 26% wt of acid peroxide solution and demineralized water for 15, 60, and 120 minutes, respectively. Next, the EFBs were torrefied at 300 °C for 60 minutes. The 18% wt acid peroxide solution pre-treatment for 120 minutes has shown the best result with an ash content of 3.94% wt, volatile matter of 32.42% wt, and fixed carbon of 64.08% wt. Furthermore, the 60-minute demineralized water pre-treatment achieved the best results, reducing the potassium content by 30% (from 1.650% wt. to 1.144% wt.) and the chlorination by 48% (from 0.031% wt. to 0.016% wt.). The quality of EFB after burning largely meets the standards set by SNI 8675:2018. It has a maximum density of 0.8 g/cm3, a maximum water content of 12% wt., a maximum ash content of 5% wt., and a volatile matter content of 80% wt
