Future Energy

Effect of piston bowl geometry on combustion, performance, and emission characteristics of a dual-fuel engine

Abdullah Al Rifat, Md. Mizanur Rahman, Md. Arafat Rahman — Wed, 01 Oct 2025 00:00:00 +0000

The piston bowl shape plays a crucial role in turbulence, swirl, and subsequent fuel-air mixing, which in turn affect combustion, emissions, and performance attributes. A cylinder stepped and modified re-entrant combustion chamber was investigated through Ansys Forte 2023 R1 CFD software to analyze combustion, emission, and performance characteristics in a diesel-methane dual-fuel engine. Numerical investigation is performed under 0.44 MPa load, 50% methane energy contribution, 7° start of injection bTDC, and with a 120° spray angle. Methane is injected into the inlet manifold to be premixed with air. The maximum thermal efficiency was found to be 34.11%, and a specific fuel consumption of 270.44 g/kW-h was indicated by the modified re-entrant bowl shape. The combustion duration for a modified re-entrant is 6.73% and 14.38% higher than that of a cylinder and stepped bowl. Higher combustion efficiency, combustion duration, and total apparent heat release demonstrate sustained combustion in the modified re-entrant bowl. Strong early premixed combustion in a cylinder-shaped bowl gives the highest percentage of NOx. The stepped bowl has fuel-rich zones near the center after 19° CA, with lower temperatures near the center, giving higher amounts of UHC and VOC emissions. The amount of O and OH radical formation in the modified re-entrant bowl was lower, and delayed oxidation resulted in a higher amount of CO emission. The modified re-entrant bowl offered the best combustion, performance, and emission attributes among the bowl shapes.

The expansion of BRICS and its impact on the use of renewable energy sources: a case study of hydrogen energy

Rahamat Hajimineh, Parisa Sabri, Ebrahim Rezaei Rad — Mon, 20 Oct 2025 00:00:00 +0000

Considering the increasing energy needs and environmental challenges in the world, BRICS members have also put in place a policy of reducing dependence on fossil fuels and moving towards more sustainable energy sources. This study aims to investigate the role and impact of the expansion of this bloc on the development and use of renewable energies, with a special focus on hydrogen energy. In this article, the combined method (quantitative and qualitative) and the theoretical framework of sustainable development and energy transition have been employed. Based on the results, BRICS can play an important role in accelerating the development of hydrogen energy by using policies such as knowledge and technology exchange between member countries, increasing investment in research and development of hydrogen energy, and financing hydrogen energy production infrastructure projects by the new BRICS Development Bank.

Advanced passive heat transfer enhancement: numerical analysis of TiO₂-water nanofluid flow in tubes fitted with twisted tape and conical ring inserts

Itquan Hossen, Prasanjit Das, Ashraful Zannat Akhi — Sun, 09 Nov 2025 00:00:00 +0000

The primary objective of this study is to investigate the heat transfer enhancement, friction factor, and thermal performance factor of a plain tube with single and double twisted tapes, combined with a semicircular cut with and without dimples, a perforated V-cut, and conical rings, using a TiO2-water nanofluid. Numerical simulations of tube flow and heat transfer were conducted. The nanofluid used in the simulations contains TiO₂ nanoparticles at concentrations of 0.5% and 1.5% by volume. The nanofluid inlet temperature was set at 300 K, and boundary conditions were applied. The maximum heat transfer coefficient increases from plain tube to 88.2% and 71.42% at double twisted tape with perforated V-cut and semi-circular cut, respectively, with dimples in 0.5% and 1.5% TiO₂ concentrations. The maximum Nusselt number increased by 115.53% and 100.9% at double twisted tape with perforated v-cut and semi-circular cut with dimples compared to the plain tube in 0.5% and 1.5% TiO₂ concentrations, respectively. The simple tube with a perforated V-cut and a conical ring insert exhibits a 94.44% higher friction factor at a 1.5% TiO₂ concentration. The maximum thermal performance factor was found to be 2.04 for double twisted tapes at a 0.5% TiO₂ concentration. Additionally, this study presents contour plots of the velocity distribution, pressure distribution, temperature distribution, and turbulent kinetic energy.

Numerical study of MHD mixed convection in an oriented elliptic geometry under the influence of some selected geometrical variables and fluid flow properties saturated with Al2O3-water nanofluid

T. Adekeye, P.O. Okekunle, I.K. Adegun — Tue, 09 Dec 2025 00:00:00 +0000

This study numerically investigated the effects of some selected geometrical parameters, such as inclination angles, eccentricity, and some fluid flow properties, such as nanoparticle volume fractions, Grashof, Hartmann, Reynolds, Prandtl, and Richardson numbers, on fluid flow pattern (velocity profiles), temperature history, and heat transfer rate in an inclined elliptic configuration filled with Al₂O₃-H₂O nanofluid. The non-dimensional governing equations were developed for the elliptic geometry. The lower wall of the configuration was subjected to continual heat flux, and the top wall was retained at a persistent cold temperature (T_c) while the cross-sectional ends of the configuration were presumed to be insulated. The normalized controlling equations were explained using a 4^th order Alternating Direction Implicit (ADI) scheme with the Gauss-Seidel iteration technique. A computer code was written with Python 3.X version to simulate the fluid flow and heat transfer in the enclosure. The numerical results obtained exhibited that fluid flow circulation deteriorated with increasing Hartmann number and increasing nanoparticle volume fraction individually. The rate of heat transfer (Nu) augmented with fluid flow circulation for the range of Grashof at 10⁴-10⁶ and φ=0.0-0.045, respectively. The temperature field decreased with increasing nanoparticle volume fractions (0.00, 0.025, and 0.045). It was revealed from the outcomes that the optimum heat transfer rates were attained in the configuration for eccentricity, e value at 0.866, and inclination angle in the range , correspondingly. The average rate of heat transfer is elevated with increasing Reynolds number under laminar conditions. The results obtained could be applied in metallurgical industries where a magnetic field is used to regulate the flow of hot fluid. It could also be useful in the development of a model for designing a compact MHD heat exchanger for industrial applications.

Ammonia as a hydrogen carrier: LES of ammonia-solid fuel firing at varying air staging ratios

Mon, 15 Dec 2025 00:00:00 +0000

Hydrogen carriers, such as Ammonia (NH₃), is anticipated to be used as a carbon-free alternative for solid fuels, such as coal. Hence, the effect of air staging ratio (ASR) on emissions from NH₃ co-firing with sub-bituminous coal was numerically investigated in a small-scale coal combustor via a Large Eddy Simulation (LES) method. The validation with experimental data demonstrated a difference in nitrogen oxides (NO_x) and temperature profiles of less than 10 %. Carbon dioxide (CO₂) and sulphur dioxide (SO₂) levels are decreasing as the NH3 percentage rises, but ASR has minimal influence. Increasing the ASR from 20 to 60 % resulted in NO_x reduction, except for 60 calorific (cal.) % NH₃, where NO_x began to grow at ASR 60 %. In the said case, peak temperature was recorded in the over-fire Air (OFA) zone due to considerable unburned carbon (UC) oxidation, resulting in an increase in thermal NO_x. Due to oxygen deficiency, coal volatiles and NH₃ are thought to burn in the firing zone due to dominant devolatilization, resulting in significant UC/char oxidation in the OFA zone. Overall, with proper ASR tuning, NH₃ co-firing can produce low CO₂, SO₂, and NO_x, and existing coal-fired utility ASR technology can be used.