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In this study, molecular-dynamics simulations were used to evaluate the nano-bubbles/droplets generated in water by CO2 hydrate dissociation. Two different simulation sets of NVT (isothermal) and NPT (isobaric/isothermal) were conducted for different CO2 concentrations and compared. The results could confirm that the CO2 agglomeration behavior changed during the simulation and observed the coexistence of CO2 nano-bubbles and nano-droplets in both systems. At first, the nano-bubbles could only be observed in the system, but some of them were turned into nano-droplets as the simulation proceeded. The NVT system is feasible to generate nano-bubbles/droplets, and the local CO2 densities are higher for the NVT system, and it can also generate slightly larger CO2 agglomeration. A higher concentration of CO2 in the solution caused more nano-droplets in both sets, while a lower concentration may only produce nano-bubbles. [ABSTRACT FROM AUTHOR]

The oxygenation of calorific fuels for use in internal combustion engines is an area of increasing research, not only in terms of thermodynamic-cycle efficiency, but also with a view towards realising reductions in emissions of environmentally harmful chemicals, e.g., CO and NOx gases. In the present work, notable progress has been achieved in the combustion efficiency of petroleum-containing air nanobubbles in an internal combustion engine, with 14% improvement achieved for combustion time on a constant-load basis in comparison to the status quo of regular petroleum. This was done by single-pass passage of atmospheric air through a tubular pipe-flow nanobubble generator based on the principle of electrostrictive capture therefrom. [ABSTRACT FROM AUTHOR]

This study aims to provide critical knowledge by investigating the dynamics of CO2 nanobubbles generated by a sustained external electric field. The evolution of the CO2 nanobubble size, population as well as the zeta potential were analysed from DLS measurements. Following a transient decay in the first few hours after NB generation, it was found that the number of NBs stabilised within 3-4 days after generation to the order of 108 per ml, whilst Ostwald ripening and expansion took place into the 100-150 nm diameter range over the same timescale. Zeta-potential measurements also indicated that this metastability was consistent with these bubble developments over the intermediate relaxation period of 3-4 days. We anticipate that the findings from this study will support the development of efficient and sustainable strategies for various technologies associated with CO2 gas. [ABSTRACT FROM AUTHOR]

The CO2-bubble-based carbonation of water using established methods is very energy-intensive with the status quo of mechanical bubble generation, and there is rapid loss of CO2 from the dispersed (bubble) phase in water, due to larger bubbles sizes in the micro-, meso- and macro-range and their associated instability. Instead, the "nano-carbonation" of water, by CO2 fine bubbles (including CO2 nanobubbles) provides for longer-lived levels of dissolved CO2. The present research details how the use of both submersible and continuous-flow nanobubble generators can boost levels of dissolved CO2 far above Henry's-Law level, and tracks longevity and decay of the dissolved-CO2 levels in the water. In particular, in the case of the submersible fine-bubble generators, both mechanical and novel electrostriction (electric-field) approaches are used, whilst in the case of pipe-based generators, hydrodynamic approaches are used for fine-bubble carbonation, with optional application of electric field to boost longer-time dissolved-CO2 levels. The decay times for the dissolved CO2 were assessed, which were a great deal longer – magnitudes – than without nano-carbonation, owing to the nanoscale CO2 keeping the overall dissolved-CO2 concentration higher with slower Fick's-Law release. [ABSTRACT FROM AUTHOR]

The bubble-based aeration of water is very energy-intensive, and there is often rapid loss of oxygen from the dispersed (bubble) phase in water, owing to larger bubble sizes in the micro-, meso- and macro-range and their associated instability. This "nano-oxygenation" of water, in contrast, by air nanobubbles offers longer-lived levels of dissolved oxygen (both in traditional- and "nano"-dissolved senses). The present research details how the use of both submersible and continuous-flow air-nanobubble generators based on an electrostriction-generation principle can boost levels of total (i.e., traditionally- and nano-) dissolved air on a sustained and long-time basis. [ABSTRACT FROM AUTHOR]