Impact Of Power Density Research Articles

Impact of power density on the drying kinetics, quality profiles, and microstructure of pork chip snacks dried by microwave vacuum drying

This study aimed to investigate how microwave vacuum drying (MVD) affects the drying kinetics, quality profiles, and microstructure of pork chip snacks (PCS). Fresh pork longissimus lumborum was sliced and dried under different power densities (4, 6, and 8 W/g) in a microwave vacuum oven. Five classical thin-layer drying models were used to evaluate the nonlinear fitting of the experimental data. The results indicated that the Midilli et al. model was the optimal model for describing the drying kinetics of PCS. Moreover, as the temperature increased during MVD, the surface of PCS gradually browned. Meanwhile, temperatures of 130.2 °C and 139.9 °C were critical for preventing severe browning and scorching of PCS. Furthermore, power densities induced accelerated drying of PCS, which led to microstructural damage and the formation of a porous structure. However, higher power density led to more pronounced drying non-uniformity of PCS, as well as severe lipid oxidation (P < 0.05), which notably altered the flavor of PCS. In summary, employing 4 W/g for 22 min in MVD emerged as the optimal parameter for PCS preparation. This study provides a novel strategy for the application of MVD in the processing of meat snacks.

Sonochemical degradation of the artificial sweetener acesulfame in aqueous medium and identification of transformation products

The sonochemical degradation of acesulfame (ACE), a widely used artificial sweetener, was investigated. The impact of power density (40 and 71 W/L), initial ACE concentration (1.5–30.6 μΜ), and initial solution pH (3–9) for the elimination of the target pollutant from water was studied. It was found that nearly complete degradation of ACE was achieved within 120 min of treatment under conditions suitable for high production of free radicals. Degradation follows a pseudo-first order kinetic model. Coupling sonochemical degradation at optimal conditions with sodium persulfate (0.2–1.0 mM) enhanced the rate of ACE oxidation by six times. The influence of water complexity was also examined; the natural occurrence of humic acid in the water matrix reduced the degradation rate, despite the fact that at least 42 % of ACE removal was achieved. Finally, LC-QToF-MS was used to evaluate the generated transformation products (TPs). Using HRMS suspect and non-target screening, seven ACE TPs were identified, and their time-trend formation profiles showed a rising trend throughout the experiment. According to the ECOSAR model, most of the identified transformation products exhibited lower toxicity than acesulfame, with one notable exception that was classified as harmful due to its acute toxicity on fish and green algae.

Characterizing the dominant ions in low-temperature argon plasmas in the range of 1–800 Torr

The dominant ions in low-temperature rare gas plasmas can be either molecular ions or atomic ions depending on the discharge regime. In this paper, the dominant ions in low-temperature argon plasmas are characterized in a wide range of gas pressure (1–800 Torr). The channels for creation of molecular ions include atom assisted association, dissociative recombination, dissociation by atom impact (DAI), and dissociation by electron impact (DEI). The latter two were previously less often considered. It is found that the DEI reaction has a significant impact on the ion fractions, while the effect of the DAI reaction is much less important in the whole investigated gas pressure regime. As the gas pressure increases from 1 to 800 Torr, the atomic ion fraction drops rapidly in conjunction with an increase of the molecular ion fraction. This phenomenon confirms that in low-temperature argon plasmas the dominant ion will be the atomic ion in the low pressure regime but the molecular ion in the high pressure regime. The impact of power density is also investigated in combination with the DEI reaction. The results show that both the DEI reaction and the power density serve to delay the transition trend of the ion fraction, shifting the dominance of molecular ions to a higher pressure.

Impacts of Power Density on Heavy Metal Release During Ultrasonic Sludge Treatment Process

The impact of ultrasonic power density on changes of heavy metals during sludge sonication was investigated. Results showed that ultrasound could release heavy metals from sludge into the supernatant. There existed an effective power density range of 0.8–1.6 W·ml−1 for the release of the total heavy metal; there was little release below 0.8 W·ml−1 and too high power density was adverse to the release. Furthermore, sonication showed selective release of heavy metal from sludge to the supernatant; copper, cadmium and lead were not released by sonication, while arsenic and nickel were released easily and their release ratio could reach 40%. The effective energy range for each heavy metal was also different that 0.8–1.2 W·ml−1 for arsenic, 0.5–1.6 W·ml−1 for nickel, and 0.8–1.6 W·ml−1 for mercury and chrome. The differences among heavy metal release during sonication might be explained by the different distribution of chemical fractions of each metal in sludge. Such selectivity could be used to control heavy metal release during sludge treatment.

A consideration of power density and hydrogen production and utilization technologies

The development of hydrogen (H 2) production systems and equipment utilizing hydrogen fuel is a key factor in the creation of a worldwide hydrogen energy network. The World Energy Network (WE-NET) project made significant progress in its development work in FY2002, especially in the critical area of hydrogen fueling stations. This report will examine some of the highlights of the FY2002 WE-NET project, and will also consider the impact of power density on fuel cell cost. Hydrogen production method also evaluated by scale merit (kW/m 3).