Search Results (2)

Material treatment in pulsation reactors (PRs) offers the potential to synthesize powdery products with desirable properties, such as nano-sized particles and high specific surface areas, on an industrial scale. These exceptional material characteristics arise from specific process parameters within PRs, characterized by the periodically varying conditions and the resulting enhanced heat and mass transfer between the medium and the particulate material. Understanding flame behavior and the re-ignition mechanism is crucial to controlling the efficiency and stability of the pulse combustion process. In order to accomplish this objective, an investigation was conducted into flame behavior within the combustion chamber of a Helmholtz-type pulsation reactor. The study was focused on primarily analyzing the flame propagation process and examining flame velocity throughout the operational cycle of the reactor. Two optical methods—natural flame luminosity (NFL) and particle image velocimetry (PIV)—were applied in related experiments. An analysis of the NFL measurement data revealed a correlation between the intensity of light emitted by the pulsed flame and the air-fuel equivalence ratio (range from 0.89 to 2.08 in this study). It is observed that a lower air-fuel equivalence ratio leads to higher flame luminosity in the PR. In addition, in order to study the parameters related to system stability and energy transfer efficiency, this study also focuses on the local velocity field measurement method and an example of a fluid flow result in a combustion chamber by using a phase-locked PIV measurement system upgraded from a classic PIV system. The presented results herein contribute to the characterization of flame propagation within a pulsation reactor, as well as in pulsatile flows over one working cycle in a broader context, with flow velocity in the center of the combustion chamber ranging from 1.5 m/s to 5 m/s. Furthermore, this study offers insights into the applicable experimental methodologies for investigating the intricate interplay between flames and flows within combustion processes. Full article

Considerable efforts have been spent on environmentally friendly particles for the encapsulation of essential oils. Polymeric particles were developed to encapsulate the essential oil from Piper nigrum based on gelatin and poly–ε–caprolactone (PCL) carriers. Gas Chromatography ((Flame Ionization Detection (GC/FID) and Mass Spectrometry (GC/MS)), Atomic Force Microscopy (AFM), Nanoparticle Tracking Analysis (NTA), Confocal Laser Scanning Microscopy (CLSM), Attenuated Total Reflectance–Fourier-transform Infrared Spectroscopy (ATR–FTIR), and Ultraviolet–Visible (UV–VIS) spectroscopy were used for the full colloidal system characterization. The essential oil was mainly composed of β-caryophyllene (~35%). The stability of the encapsulated systems was evaluated by Encapsulation Efficiency (EE%), electrical conductivity, turbidity, pH, and organoleptic properties (color and odor) after adding different preservatives. The mixture of phenoxyethanol/isotialzoni-3-one (PNE system) resulted in enhanced stability of approximately 120 and 210 days under constant handling and shelf-life tests, respectively. The developed polymeric system presented a similar controlled release in acidic, neutral, or basic pH, and the release curves suggested a pulsatile release mechanism due to a complexation of essential oil in the PCL matrix. Our results showed that the developed system has potential as an alternative stable product and as a controlling agent, due to the pronounced bioactivity of the encapsulated essential oil. Full article