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Design and Analysis of Venturi Microbubble Generator Using Computational Fluid Dynamics Thoharudin, Thoharudin; Sunardi, Sunardi; Yudha, Fitroh Anugrah Kusuma; Nadjib, Muhammad; Nugroho, Arif Setyo
Eksergi Vol. 19 No. 2 (2023): MAY 2023
Publisher : Politeknik Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32497/eksergi.v19i2.4305

Abstract

The necessity for dissolved oxygen in water is crucial for the survival and growth of aquatic organisms, particularly tilapia. Seventy-five percent of tilapia will die if there is insufficient dissolved oxygen in the water. This work seeks to develop a venturi bubble-generating technique to combat the scarcity of dissolved oxygen in the water. A floating pump with a capacity of 12 m3/hour was selected as the medium for distributing water and generating vacuum pressure to draw in air for mixing with the water flow in the venturi. Ansys Fluent was used to model piping and venturi systems. The piping system was modeled with a single-phase (water) flow at a steady state, whereas the flow in the venturi was modeled with a multiphase (air and water) flow under transient situations. The simulation findings revealed that the pressure drop at the 90-degree elbow was much greater (27.17 kPa) than that at the 45-degree elbow (16.53 kPa). A 1-inch input diameter venturi produced bubbles with an average diameter of 105 µm, whereas a ½  inch venturi bubble generator produced bubbles with an average diameter of 83 µm. Owing to the numerous advantages of adopting a six-outlet piping system with a ½ inch venturi, this design is recommended for floating pumps with a capacity of 12 m3/h.
Physical property analysis of biodiesel from nyamplung and used cooking oil: density, viscosity, calorific value, and flash point Wahyudi, Wahyudi; Nadjib, Muhammad; Faizi, Achmad
Jurnal Polimesin Vol 22, No 2 (2024): April
Publisher : Politeknik Negeri Lhokseumawe

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30811/jpl.v22i2.4565

Abstract

The increasing dem and for energy and the depletion of fossil fuel shas led to the exploration of alternative fuels like biodiesel, which require sref inement tomatch diesel oil properties. This study investigates the combination of nyamplung oil, a non-edible potential source, with waste cooking oil for biodiesel production, aiming to improve its physical properties. Through a method ological approachin volving degumming, esterification, and transesterification, biodiesel was produce dfrom these oils in 11 different blend compositions. The physical properties of these blends, including density, viscosity, flashpoint, and calorific value, were rigorously tested. Results indicate that incorporating waste cooking oil into nyamplung biodiesel significantly reduces viscosity, density, and flashpoint while increasing the calorific value. Specifically, the addition of waste cooking oil altered the density from 912.74 kg/m³ in pure nyamplung biodiesel to 857.27 kg/m³, decreased the viscosity from 28.02 cStto 4.58 cSt, reduced the flash point from 223°C to 197°C, and increased the heating value from 7,626.59 cal/g to 8,348.94 cal/g.