Energy and Thermofluids Engineering

Extraction and characterization of biodiesel from waste cooking oil: An investigative approach based on the number of times used

Sat, 17 Aug 2024 00:00:00 +0000

In the era of rising atmospheric pollution and carbon dioxide emissions, environmentally sustainable energy sources are essential. This study seeks to address this challenge by examining the potential of biofuels, namely biodiesel derived from discarded waste cooking oil. The primary objective was to employ substantial quantities of wasted cooking oil, often generated by households and companies, in order to produce a biodiesel substitute that has a diminished environmental footprint in comparison to conventional diesel fuel. The procedure involved the synthesis of biodiesel through the transesterification of waste cooking oil samples, utilizing Methyl alcohol (CH₃OH) and Sodium hydroxide (NaOH) as a catalyst. The collected biodiesel samples were analyzed for important parameters, such as kinematic viscosity, flash point, and density. The kinematic viscosity values for the 10th, 20th, and 30th samples were 5.59 centistokes, 5.46 centistokes, and 4.91 centistokes, respectively. The flash points were determined to be 164.4 °C, 165.4 °C, and 148.4 °C, with densities of 0.8889 g/cc, 0.8891 g/cc, and 0.8891 g/cc, respectively. This study conducts a comprehensive examination and comparison of the characteristics of several biodiesel samples to ascertain the most advantageous choice. Moreover, a comparative assessment is carried out to determine the environmental benefits of the biofuel produced, as compared to conventional diesel. The findings offer crucial perspectives for the discourse on sustainable energy sources, emphasizing the potential of utilizing waste cooking oil-derived biodiesel as a viable and eco-friendly alternative to fossil fuels. By transforming waste cooking oil into biodiesel and carefully assessing its properties during synthesis, this research takes an innovative method.

Heat transfer performance analysis through inline and staggered grooved microchannel using lattice Boltzmann method

RUNU BISWAS, M. M. Rahman, A. Khanom, M. A. Taher — Sun, 22 Sep 2024 00:00:00 +0000

The D2Q9 Bhatnagar-Gross-Krook (BGK) model, utilizing the Thermal Lattice Boltzmann Method (TLBM) to examine the temperature and mass transfer numerically across inline and staggered grooved microchannels. The conditions are (a) cold fluid at inlet and outlet, (b) walls are heated (c) relative roughness height is rh=4%, 8% and 12% according to channel height and (d) parabolic velocity profile at inlet and outlet section with slip flow at the walls for different Knudsen numbers from Kn=0.02 to 0.10. The study goals to examine the impact of temperature profiles, Nusselt number, average friction coefficients and performance analysis of smooth, inline and staggered grooved microchannels. The friction coefficient is defined as the ratio of the Poiseuille number (Pn) and Reynolds number (Re) and the dimensionless heat transfer recognized by the Nusselt number (Nu) has been studied to investigate the roughness effects of the surface. The result presented that the average friction increased gradually with the height of relative roughness and reduced significantly with growing Kn for both inclined and staggered grooved microchannels. In addition, compared to smooth, inline and staggered microchannels, the lowest friction occurred for smooth and the highest friction showed for inline grooved channels. The maximum average friction factor is depicted as 107.053 for inline grooved microchannels when rh=12% and Kn is 0.02. The extreme heat transfer rate is found to be 9.015 when the microchannel is smooth and Kn=0.02. The highest performance PE=1.013248 is exhibited by the staggered microchannel when Kn=0.02 and with rh=12%. Compared to the inline grooved channel, the staggered grooved microchannel has demonstrated better performance.

Techno-economic feasibility analysis for gas turbine and reciprocating engine-based power generation using biogas: A case study of Karachi, Pakistan

Mon, 21 Jul 2025 00:00:00 +0000

The dependency on imported fossil fuels increases cost and environmental issues. Karachi the biggest and most densely populated city of Pakistan is experiencing severe energy shortage issues. This feasibility study evaluates the biogas transformation of Karachi city waste-to-energy utilizing conventional systems with few emissions. An estimation of energy potential was carried out to determine the potential generated in Karachi city for power generation using municipal waste. A modified energy model was used to determine the cooling load for a 100 kW power generation plant. The measurement of mathematical formulations was observed to monitor the affectivity of biogas generation. This study utilizes a biogas digester with anaerobic treatment technology to convert organic waste to energy. Feasibility analysis of this data is conducted in RETScreen Clean Energy Analysis software to compare different clean energy techniques. This feasibility is conducted for a 100 kW Power plant. Two options for power generation using biogas were selected i.e. reciprocating engine and gas turbine. The proposed reciprocating engine-based cooling system initial total cost of the biogas system is US 415,000 $ while gas turbine cost is 120,000 $ with payback period of 15 years. The proposed reciprocating engine produces 305 t CO? with 87.1% and gas turbine produces 16,600 t CO? with 38.4%. Results showed a cumulative comparative analysis among gas turbine and reciprocating engines that examines that reciprocating engine is recommended for high power efficiency with few emissions. The reciprocating engine has a better predicting ability for power generation with less carbon emissions, which is one of the key findings of the present study.

Optimizing Proton Conductivity in Sulfonated Polystyrene Membranes via Phosphorous Pentoxide Doping

Mosiur Rahaman, Khurshida Sharmin — Sat, 02 Aug 2025 00:00:00 +0000

Recently, Proton conducting membrane fuel cells (PCMFCs) have been recognized as a potential future and excellent medium for efficient power sources. In this present work, Polystyrene has been used to make a proton conductive membrane, mixing with phosphorus pentoxide (P₂O₅), targeting to achieve low cost and high proton conductivity under low humidity conditions. Several membranes are studied with varying amounts (three compositions: 5 wt.%, 10 wt.%, and 20 wt.%) of P₂O₅ concerning polystyrene weight and doped in 20% diluted sulfuric acid. It is expected that a new proton transport pathway is provided between the phosphoric acid and sulfuric acid in dry conditions. Results of conductivity, obtained by Electrochemical Impedance Spectroscopy (EIS), have shown excellent proton conductivity at room temperature. The 10 wt.% modified P₂O₅ membrane exhibited a higher order of proton conductivity, approximately two orders of magnitude compared to pure PS membrane at dry conditions (approximately 10^-2 S/cm), which is the highest value among the fabricated membranes. The Fourier transform infrared spectrometer (FTIR) analysis confirmed the sulfonation of the modified membranes. These membranes are also characterized by scanning electron microscopy (SEM) and tensile test. The tensile test showed the highest strength of 1.8 MPa; while the SEM images proved the porous structure of the membranes, which is helpful to improve the proton conducting membrane (PCM) structure. So, the 10 wt.% P₂O₅ modified membrane Is a promising candidate as a novel PCM and have potential applications for use in fuel cells.