Despite the exciting potential of microgrids in future smart energy systems, they encounter significant challenges, including fluctuations in energy demand and output, as well as the unpredictable behavior of electric vehicles. This article examines the ability of microgrids to enhance the integration of renewable energy sources to achieve Zero-Energy Buildings (ZEBs) and facilitate the deployment of Vehicle-to-Grid (V2G) technologies. The designed microgrid comprises vehicles utilizing V2G technology for daily energy storage and a hydrogen cycle featuring electrolyzers and fuel cells for seasonal storage. Probability functions based on uncertainty for distance, arrival, and departure periods from charging stations are formulated to mitigate uncertainties associated with electric vehicles (EVs). A genetic algorithm is employed to optimally regulate EVs' charging and discharging range and the hydrogen cycle's dynamic configuration. The system's feasibility is evaluated for a district in Tehran, characterized by a hot semi-arid climate per the Köppen climate classification, comprising 600 EVs and 3000 residential and 55 commercial buildings. The performance of the suggested smart system is compared with traditional scenarios from techno-ecological, economic, and environmental perspectives. The findings indicate that 62.6 % of the overall energy demand is met by renewable sources (wind and solar), and the microgrid can independently fulfill the need for over 50 % of the year, owing to the implemented hybrid optimum controllers. The findings indicate that 41 % and 16 % of total renewable electricity generation are stored in hydrogen systems and electric vehicles, respectively, highlighting their significant potential for both short-term and long-term storage. Compared to the same traditional scenarios, the suggested system, with an annual energy gain of 8.9 GWh, exhibits superior performance due to its little reliance on the grid while simultaneously ensuring the happiness of electric vehicle owners and the stability of energy storage systems. The intelligent microgrid demonstrates significant efficiency, conserving over 12,600 MWh of energy and decreasing more than 8800 tons of CO<inf>2</inf> emissions. Furthermore, this system generates a substantial financial benefit of approximately USD 468,000, highlighting its notable environmental and economic merits.

This study presents a comprehensive investigation into CO<inf>2</inf> absorption in a pilot-scale, multi-nozzle spray tower operating under industrial conditions. Through the integration of pilot-scale experimentation and reactive CFD modeling, this work advances the quantitative understanding of coupled hydrodynamic behavior and mass transfer phenomena in conditions representative of full-scale operations. A modular carbon capture unit was built and deployed at a Swedish waste-to-energy facility to experimentally investigate gas–liquid flow behavior and CO<inf>2</inf> absorption performance using a 15 wt% NaOH solution as the absorbent. The experimental data provided the basis for validating a reactive Euler–Lagrange multiphase CFD model, which elucidated gas–liquid interactions, including droplet dispersion, turbulent flow structures, mixing, and interphase mass transfer. Sensitivity analyses across a range of gas (50–200 m³/h) and liquid flow rates demonstrate how operating conditions influence droplet trajectories, residence time, and CO<inf>2</inf> absorption efficiency. Flow segmentation identifies two distinct zones where turbulence and recirculation enhance mixing and mass transfer, with side gas inlet configurations providing more effective radial mixing compared to axial inlet designs. Results demonstrate that tuning the liquid-to-gas (L/G) ratio, droplet characteristics, and gas inlet design significantly influences CO<inf>2</inf> capture, offering practical guidance for the next generation of spray-based carbon capture systems. The study investigated L/G ratios ranging from 2.3 to 7.0 kg/kg and examined the effects of droplet sizes between 200 and 3000 μm, observing that droplets predominantly in the lower size range exhibited improved dispersion and extended residence times, which are favorable for effective CO<inf>2</inf> absorption. The findings provide a direct basis for optimizing hydrodynamics and scaling spray tower absorbers for effective CO<inf>2</inf> capture in real-world systems.

Spray towers have proven to be efficient in capturing gases and vapours, finding widespread use across various applications including CO₂ capture. As there is scarce reference material regarding spray tower performances with different flow configurations other than the conventional counter-current flow, as well as the use of substitute solvents to MEA, there is a need to study different configurations and setup designs, including different placements of gas and liquid inlets in the absorber tower, to find the optimal configuration. In this study, the capture of CO₂ from a CO₂/N₂ mixture using unpromoted potassium carbonate as the absorbent in a lab-scale spray tower was experimentally measured in four different flow configurations over a wide range of operating conditions, including gas and liquid flow rates, CO₂ concentration, K₂CO₃ concentration and solvent temperature. Among four different configurations, the two sides co-current configuration, with gas nozzles positioned on opposite sides of the column and liquid coming from above, was found to be the most effective setup for enhancing CO₂ capture efficiency by promoting better mixing and contact between gas and liquid.

The rising global warming concerns make it inevitable to phase out fossil fuels sooner rather than later, as they contribute to about 60% of the greenhouse gas emissions in the world. One alternative to fossil fuels in heavy industry is green hydrogen. However, hydrogen combustion in air is known to emit the oxides of nitrogen (NOx) which are harmful to health. An improved comprehension of these NOx emissions and their formation pathways is the first step towards their mitigation. This paper intends to improve the methodology to understand the NO formation pathways in a non-premixed, swirl-stabilised, hydrogen/air gas-turbine combustor. To do so, high-fidelity large-eddy simulations (LESs), extended proper orthogonal decomposition (EPOD) technique and zero-dimensional (0D) perfectly stirred reactor (PSR) analyses are combined to utilise the merits of each of these techniques. While the LES ensures that the flow-field and reactions are well captured, EPOD is applied to identify two points featuring high positive and high negative fluctuations of the rate of production of NO, i.e. ROPNO, respectively. The 0D PSR provides a platform for a cost-effective yet detailed chemical pathway analysis at these identified points. Although both NO production and consumption reactions are prevalent at the chosen points, the net effect is that of NO production as was evidenced by the positive value of ROPNO at these points. However, the rate of production of NO differed between the two points. While the major NO formation and consumption reactions were found to be the same at both the points, their contributions to overall ROPNO varied. The major NO production reaction at both the points was NNH+O NH+NO, contributing to 37% and 26% at the points with high positive and high negative ROPNO fluctuations, respectively. Moreover, the species composition was different at the chosen points, which is expected in a non-premixed combustion configuration. For instance, the mass fractions of NNH and O, i.e. the reactants in the major NO production reaction, were respectively 18.28% and 8.77% higher at the point with high positive ROPNO fluctuation compared to the point with high negative ROPNO fluctuation. The above-mentioned differences in the reactions' contributions to ROPNO at the chosen points could be attributed to such variation in local composition, which is highly likely in non- premixed combustion. The methodology proposed in this paper enables a detailed chemical pathway analysis emphasising the points featuring high ROPNO fluctuations. This technique, which conducts a focused analysis of the NO formation pathways in a combustor, can be a useful tool in the effort towards designing cleaner hydrogen combustors.

To achieve intensified and uniform heat transfer particularly in low-temperature environments, this work investigates using reversible reactive fluid N2O4/NO2 in a multi-jet impingement cooling configuration for low-grade waste heat recovery. Five impinging jets arranged in an equilateral staggered pattern are analyzed by high-fidelity large eddy simulations to reveal flow dynamics, temperature distribution, species concentration, and chemical reactive behaviors. Time-mean results indicate that the combination of near-wall heat-absorbing and far-wall heat-releasing reactions significantly amplifies the wall-normal temperature gradient, resulting in up to 300% Nusselt number enhancements compared to the case without reaction. The reaction exhibits a limited impact on vortical structures from the opposing influences of viscosity increasing and molecular expansion. Instantaneous Nusselt number peaks migrate radially outward from the different jet centers and merge in the middle between adjacent jets, driven by the movement and break-up of unsteady vortex-rings. Proper Orthogonal Decomposition (POD) analysis further confirms that the vortex-ring structures are key contributors to the turbulent energy in the multi-jet impinging system. These small-scale eddies disrupt the local chemical equilibrium, triggering unsteady alternating shifts between endothermic and exothermic behaviors. Moreover, the instantaneous Nusselt number in the reactive case consistently remains 200% to 300% higher than that in the non-reactive cases.

In accordance with the United Nations Sustainable Development goal #7 – affordable and clean energy, the concept of reversible reactive flow (N2O4/NO2) inside ribbed channel is proposed for low-temperature waste heat recovery. Quasi direct numerical simulations are performed to reveal the relationship between flow, heat/mass transfer, and chemical characteristics with different rib inclined angles (90° and 45°). The analyses indicate that the reaction of N2O4 ⇌ 2NO2 has limited influence on flow patterns inside the ribbed channel, but intensifies the heat transfer considerably. For the 90° reactive case, the enhancement of Nusselt number reaches 112.7 % when Reynolds number is 2000. Although non-equilibrium thermal-chemical phenomenon is observed by instantaneous snapshots, time-averaged results show that the forward endothermic reaction is concentrated close to the heated wall. The flow structures transport fluid pocket consisting of “overheated” gas and triggers local backward exothermic reaction, which decreases the thickness of thermal boundary layer and thereby intensifies the overall heat transfer. For the 45° inclined reactive case, a flow circulation at local equilibrium between heat release and absorption is formed by the rib-induced large-scale vortices. The comprehensive thermal performance is further improved by 24.6 % compared to the 90° reactive case, which attributes to higher Nusselt number and lower friction loss.

The trend toward thinner and lighter electronic devices necessitates developing advanced thermal management solutions to address modern microprocessors’ escalating heat dissipation demands. This study introduces an advanced thermal solution incorporating a gyroid TPMS structure with remarkable physical properties for microprocessor cooling. Detailed investigations were conducted using a full-scale heat sink model to understand the inner geometric structure, flow, and heat transfer characteristics within a gyroid heat sink (GHS). The thermo-hydraulic performance of the GHS design was systematically assessed against that of a pinfin heat sink (PHS) across different porosities and flow rates. Both heat sinks were evaluated under non-uniform heating conditions, considering three heating schemes, each with eleven randomly distributed hotspots. The thermohydraulic performance was assessed by calculating temperature non-uniformity, thermal resistance, and pumping power. A correlation was established using the cell size and cell wall thickness of a unit cell of gyroid TPMS to calculate its hydraulic diameter. The analysis revealed that the enhanced thermal performance of the GHS design can be attributed to its intricate and convoluted flow structure, along with a significantly large heat transfer surface area. However, these same factors contribute to a notably high-pressure drop. Compared to the PHS design, the GHS design showed better thermal performance at all the selected porosities and flow rates, albeit with higher pumping powers. The GHS design showed improvement in the thermal performance as the porosity decreased. Investigation under heterogeneous heating conditions showed substantially lower temperatures at the hotspots in the GHS design, along with reduced temperature variation among them. The study's findings provide valuable insight into the advantages and drawbacks of gyroid TPMS structure for their application in electronic cooling.

Computationally inexpensive reduced order models such as Chemical Reactor Networks (CRN) are encouraging tools to obtain fast numerical solutions. However, the accuracy of such models is usually compromised compared to experiments or high-fidelity numerical simulations. Therefore, continued improvement of such models is necessary to ensure reasonable accuracy and fill the need for computationally inexpensive tools. To that end, inputs from computational fluid dynamics simulations have been used to build CRNs in the last 25 years. This can be further improved by the application of data-driven techniques. The present work uses a novel data-driven analysis based on high-fidelity simulation results where the high-dimensional data is first reduced to a low-dimensional manifold and is then clustered into chemically coherent regions. These results along with the high-fidelity simulation results are used to construct a CRN for wet combustion simulations. Wet combustion is a novel clean combustion technique, where an increase in the level of steam dilution distributes the flame, with a risk for flame extinction. This phenomenon, i.e., humid blowout (HBO), was modelled using the above-mentioned CRN. The HBO predicted by the CRN was also tested for thermal power, equivalence ratio, and fuel conditions different from its design point. The error in HBO prediction was quantified by comparing the steam-dilution level at HBO obtained using CRN and that obtained experimentally. The CRN predicted the HBO with an error magnitude less than 5% when the thermal power was unchanged. The maximum error in all tested conditions was 16.65%. Furthermore, a sensitivity analysis revealed that the inclusion of hot gas recirculation through the central recirculation zone, quantified by the mass flow split between the post-flame region and the CRZ, is important in the prediction of HBO, although its accuracy is inconsequential.

Thermal hotspots cause excessive localized temperature rise, leading to significant temperature gradients across the microprocessor, which is the primary reason for its inadequate performance and early failure. This study proposes microchannel-pinfin hybrid heat sinks incorporating twisted and non-twisted pinfins of various cross-sectional shapes (hexagonal, pentagonal, square, and triangular) to demonstrate energy-efficient hotspot mitigation in a microprocessor with highly non-uniform power distribution. Microchannels and pinfins are positioned at low- and high-heat-flux zones, respectively, to reduce the temperature variations utilizing their unequal heat transfer capabilities. Here, high- and low-heat-flux zones represent the microprocessor-core area (hotspot) and remaining chip area (background zone), characterized by heat fluxes of 300 W/cm2 and 50 W/cm2, respectively. The pinfin twisting angle varies from 0° to 360° at a step of 45°. Conjugate heat transfer analyses are conducted through numerical solutions of the continuity, Navier-Stokes, and energy equations. The performance of the proposed hybrid heat sinks is compared with the non-hybrid (NH) and hybrid circular pinfins (HCP) heat sinks at Re = 120–440. The hybrid heat sink featuring triangular pinfins twisted at 225° angle (HTP-225) exhibits a remarkable reduction of 48.2 % in the total thermal resistance (Rth) and 58.4 % in the temperature non-uniformity (δT,bs) as compared to the NH heat sinks at Re = 440. Compared to the HCP design, the HTP-225 design shows 26.9 % and 35.8 % lower Rth and δT,bs, respectively. Moreover, the HTP-225 heat sink outperforms the NH heat sink with 46.0 % and 57.0 % lower Rth and δT,bs, respectively, at an equal pumping power of 18.6 mW. Furthermore, the HTP-225 heat sink demonstrates a 96.4 % and 38.5 % higher critical hotspot heat flux dissipating capacity than the NH and HCP heat sinks, respectively, making it a viable and effective solution for alleviating hotspots in high-power-density devices.

As part of global efforts to reduce greenhouse gas emissions, the automotive industry is moving towards the electrification of its fleet – including full electric and hybrid vehicles. Considering hybrid vehicles, the energy efficiency and thermal management of powertrains including IC engines remains an important contribution. In this regard, engineers need accurate tools to understand heat-transfer in engine bays. This work presents a flexible test rig design to be used for the validation of CFD simulations of an underhood environment. The test rig and measurement equipment are introduced in detail with experimental data (and CAD) being available. A possible test scenario presented in this research is when an engine is subjected to heavy loads (i.e., constant uphill driving) and the vehicle is subsequently stopped. The experimental results are analysed and, furthermore, the data in terms of flow and temperature fields is compared against the results of the numerical simulations. This sort of comparison is the main usage scenario for the constructed rig, and it demonstrates the value of this facility for research. The rig's geometry and the experimental data being available can additionally be used to facilitate development and validation of various CAE methodology as well as simulation techniques.