scholarly journals Effect of Machine Smoking Intensity and Filter Ventilation Level on Gas-Phase Temperature Distribution Inside a Burning Cigarette

2015 ◽  
Vol 26 (4) ◽  
Author(s):  
Bin Li ◽  
Lucan Zhao ◽  
Chuanfang Yu ◽  
Chuan Liu ◽  
Yi Jing ◽  
...  
Keyword(s):  
Gas Phase ◽  
Medium Temperature ◽  
Smoking Intensity ◽  
Contour Maps ◽  
Distribution Parameters ◽  
Temperature Ranges ◽  
Phase Temperature ◽  
Burning Coal ◽  
Complex Temperature ◽  
Data Extracting

AbstractAccurate measurements of cigarette coal temperature are essential to understand the thermophysical and thermo-chemical processes in a burning cigarette. The last system-atic studies of cigarette burning temperature measurements were conducted in the mid-1970s. Contemporary cigarettes have evolved in design features and multiple standard machine-smoking regimes have also become available, hence there is a need to re-examine cigarette combustion. In this work, we performed systematic measurements on gas-phase temperature of burning cigarettes using an improved fine thermocouple technique. The effects of machine-smoking parameters (puff volume and puff duration) and filter ventilation levels were studied with high spatial and time resolutions during single puffs. The experimental results were presented in a number of differ-ent ways to highlight the dynamic and complex thermal processes inside a burning coal. A mathematical distribution equation was used to fit the experimental temperature data. Extracting and plotting the distribution parameters against puffing time revealed complex temperature profiles under different coal volume as a function of puffing intensities or filter ventilation levels. By dividing the coal volume prior to puffing into three temperature ranges (low-temperature from 200 to 400 °C, medium-temperature from 400 to 600 °C, and high-temperature volume above 600 °C) by following their development at different smoking regimes, useful mechanistic details were obtained. Finally, direct visualisation of the gas-phase temperature through detailed temperature and temperature gradient contour maps provided further insights into the complex thermo-physics of the burning coal. [Beitr. Tabakforsch. Int. 26 (2014) 191-203]

Thermal Properties of Fullerene С56

2021 ◽  
Vol 1040 ◽  
pp. 15-20
Author(s):  
Nikolay M. Barbin ◽  
Lydia V. Yakupova ◽  
Dmitriy I. Terentev ◽  
Valery T. Kuanyshev
Keyword(s):  
Thermal Properties ◽  
Gas Phase ◽  
Least Squares Method ◽  
Equilibrium Constants ◽  
Calculated Data ◽  
Nitrogen Atmosphere ◽  
Higher Fullerenes ◽  
Temperature Ranges ◽  
Gas Phase Dissociation ◽  
Phase Temperature

The behavior of С56 fullerene when heated in a nitrogen atmosphere at a pressure of 105 Pa was studied using computer thermodynamic modeling. The modeling consisted in a complete thermodynamic analysis of the system using the TERRA software package, which is one of the most developed and efficient ones that implements such thermodynamic calculations. Experiment temperature ranges are from 273 to 3373 К. Based on the calculated data, a graph of the carbon balance in the С56-N2 system was constructed, the ongoing physicochemical processes were described, divided into four classes: sublimation, dissociation in the gas phase, chemical reactions occurring in the gas phase, dissociation and chemical reaction in the gas phase. Temperature intervals of reactions are identified. The equilibrium constants of the reactions are calculated and described, as well as the coefficients of these constants are found using the least squares method. The temperature interval of thermal stability of the condensed C56 fullerene and C56 vapors is defined. This work is one of the series of works on the properties of nanoparticles, in the future it is planned to study the thermal properties of higher fullerenes. The data obtained can be used to determine the explosive and fire hazardous properties of fullerenes as a dispersed solid.

Comparative Study of GaN Growth Process by MOVPE

1999 ◽  
Vol 572 ◽  
Author(s):  
Jingxi Sun ◽  
J. M. Redwing ◽  
T. F. Kuech
Keyword(s):  
High Temperature ◽  
Comparative Study ◽  
Gas Phase ◽  
Residence Time ◽  
Gas Flow ◽  
Flow Sheet ◽  
Flow Zone ◽  
High Quality ◽  
Phase Temperature ◽  
High Temperature Gas

ABSTRACTA comparative study of two different MOVPE reactors used for GaN growth is presented. Computational fluid dynamics (CFD) was used to determine common gas phase and fluid flow behaviors within these reactors. This paper focuses on the common thermal fluid features of these two MOVPE reactors with different geometries and operating pressures that can grow device-quality GaN-based materials. Our study clearly shows that several growth conditions must be achieved in order to grow high quality GaN materials. The high-temperature gas flow zone must be limited to a very thin flow sheet above the susceptor, while the bulk gas phase temperature must be very low to prevent extensive pre-deposition reactions. These conditions lead to higher growth rates and improved material quality. A certain range of gas flow velocity inside the high-temperature gas flow zone is also required in order to minimize the residence time and improve the growth uniformity. These conditions can be achieved by the use of either a novel reactor structure such as a two-flow approach or by specific flow conditions. The quantitative ranges of flow velocities, gas phase temperature, and residence time required in these reactors to achieve high quality material and uniform growth are given.

scholarly journals Rapid compressions in a captive bubble apparatus are isothermal

2003 ◽  
Vol 95 (5) ◽  
pp. 1896-1900
Author(s):  
Wenfei Yan ◽  
Stephen B. Hall
Keyword(s):  
Hydrostatic Pressure ◽  
Gas Phase ◽  
Pulmonary Surfactant ◽  
First Order ◽  
First Order Kinetics ◽  
Gas Phase Molecules ◽  
Actual Change ◽  
Phase Temperature ◽  
Two Phases ◽  
Interfacial Films

Captive bubbles are commonly used to determine how interfacial films of pulmonary surfactant respond to changes in surface area, achieved by varying hydrostatic pressure. Although assumed to be isothermal, the gas phase temperature (Tg) would increase by >100°C during compression from 1 to 3 atm if the process were adiabatic. To determine the actual change in temperature, we monitored pressure (P) and volume (V) during compressions lasting <1 s for bubbles with and without interfacial films and used P · V to evaluate Tg. P · V fell during and after the rapid compressions, consistent with reductions in n, the moles of gas phase molecules, because of increasing solubility in the subphase at higher P. As expected for a process with first-order kinetics, during 1 h after the rapid compression P · V decreased along a simple exponential curve. The temporal variation of n moles of gas was determined from P · V >10 min after the compression when the two phases should be isothermal. Back extrapolation of n then allowed calculation of Tg from P · V immediately after the compression. Our results indicate that for bubbles with or without interfacial films compressed to >3 atm within 1 s, the change in Tg is <2°C.

Hydrogen Production via the Iron/Iron Oxide Looping Cycle

2011 ◽  
Author(s):  
A. Singh ◽  
F. Al-Raqom ◽  
J. Klausner ◽  
J. Petrasch
Keyword(s):  
Iron Oxide ◽  
Hydrogen Production ◽  
Gas Phase ◽  
Energy Content ◽  
Operation Conditions ◽  
Iron Oxide Reduction ◽  
Temperature Ranges ◽  
Iron Iron ◽  
Gas Phase Separation ◽  
Distinct Temperature

The iron/iron-oxide looping cycle has the potential to produce high purity hydrogen from coal or natural gas without the need for gas phase separation: Hydrogen is produced from steam oxidation of iron or Wustite yielding primarily Magnetite; Magnetite is then reduced back to iron/Wustite using syngas (CO+H2). A system model has been developed to identify favorable operation conditions and process configurations. Process configurations for three distinct temperature ranges, (i) 500–950 K, (ii) 950–1100 K, and (iii) 1100–1200 K have been developed. The energy content of high temperature syngas from conventional coal gasifiers is sufficient to drive the looping process throughout the temperature range considered. Temperatures around 1000 K are advantageous for both the hydrogen production step and the iron oxide reduction step. Simulations of a large number of subsequent cycles indicate that quasi-steady operation is reached after approximately 5 cycles. Comparison of simulations and experiments indicate that the process is currently limited by chemical kinetics at lower temperatures. Therefore, product recirculation should be used for a scaled-up process to increase reactant residence times while maintaining sufficient fluidization velocity.

Production of Amino and Organic Acids from Protein Using Sub-Critical Water Technology

2013 ◽  
Vol 11 (1) ◽  
pp. 369-384 ◽  
Author(s):  
Wael Abdelmoez ◽  
Hiroyuki Yoshida
Keyword(s):  
Organic Acids ◽  
Gas Phase ◽  
Solid Phase ◽  
Water Soluble ◽  
Water Soluble Protein ◽  
Study Results ◽  
Temperature Ranges ◽  
Aggregation Step ◽  
Hydrolysis Of ◽  
Protein Bovine Serum Albumin

Abstract This work presents the hydrolysis of a water-soluble protein, bovine serum albumin (BSA), for the production of both amino and organic acids under the sub-critical water condition in the temperature range of 200–300°C. The products of the reaction were a water-insoluble solid phase, an aqueous phase, and an insignificant gas phase which was neglected in this study. Results have shown that BSA passes through an aggregation step, followed by a gel formation process which results in the formation of insoluble solid aggregates. Then, such formed solids unfolded with releasing polypeptides as an intermediate product then finally hydrolyzed to produce low molecular mass products such as amino and organic acids. It was found that there were insignificant amino acids produced in the temperature ranges of 200–225°C within 2 min and 275–300°C within 0.5 min. However, by extending the reaction time, the protein transferred to both amino and organic acids.

Comparative Thermodynamic Analysis of the Behavior of C60 and C28 Fullerenes when Heated in an Inert Medium

2020 ◽  
Vol 854 ◽  
pp. 151-157 ◽  
Author(s):  
Nikolay M. Barbin ◽  
Vasiliy P. Dan ◽  
Dmitriy I. Terentyev ◽  
Sergey G. Alexeev
Keyword(s):  
Gas Phase ◽  
Structural Changes ◽  
Molar Mass ◽  
Total Enthalpy ◽  
Thermophysical Parameters ◽  
Temperature Ranges ◽  
Volume Entropy ◽  
Energy Equilibrium ◽  
Scale Experiment ◽  
Increasing Temperature

The structural changes of condensed fullerenes C60 and C28 at a temperature increase from 200 K to 2000 K have been studied by computational methods using the TERRA software for carbon-argon systems. The processes of destruction of fullerenes C60 and C28 molecules are presented, and the temperature ranges of their thermal stability are determined: up to 1000 K and up to 400 K, respectively. The following thermophysical parameters of the C60-Ar and C28-Ar systems are considered: specific volume, entropy, total enthalpy, total internal energy, equilibrium specific heat, molar mass of the gas phase, gas constant, and mass fraction of the condensed phase. A comparative analysis of their changes with increasing temperature is carried out. The results obtained in the course of thermodynamic modeling are similar to the results of a full-scale experiment conducted under similar conditions. In the future, the obtained data can be used to determine the explosive and fire-hazardous properties of fullerenes as a dispersed solid.

scholarly journals Effect of a Lens Protein in Low-Temperature Culture of Novel Immortalized Human Lens Epithelial Cells (iHLEC-NY2)

Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2670
Author(s):  
Naoki Yamamoto ◽  
Shun Takeda ◽  
Natsuko Hatsusaka ◽  
Noriko Hiramatsu ◽  
Noriaki Nagai ◽  
...  
Keyword(s):  
Amyloid Β ◽  
Lens Epithelial Cell ◽  
Human Lens ◽  
Epithelial Cell Line ◽  
Lens Protein ◽  
Medium Temperature ◽  
Tropical Regions ◽  
Human Lens Epithelial Cell ◽  
In Silico Simulation ◽  
Temperature Ranges

The prevalence of nuclear cataracts was observed to be significantly higher among residents of tropical and subtropical regions compared to those of temperate and subarctic regions. We hypothesized that elevated environmental temperatures may pose a risk of nuclear cataract development. The results of our in silico simulation revealed that in temperate and tropical regions, the human lens temperature ranges from 35.0 °C to 37.5 °C depending on the environmental temperature. The medium temperature changes during the replacement regularly in the cell culture experiment were carefully monitored using a sensor connected to a thermometer and showed a decrease of 1.9 °C, 3.0 °C, 1.7 °C, and 0.1 °C, after 5 min when setting the temperature of the heat plate device at 35.0 °C, 37.5 °C, 40.0 °C, and 42.5 °C, respectively. In the newly created immortalized human lens epithelial cell line clone NY2 (iHLEC-NY2), the amounts of RNA synthesis of αA crystallin, protein expression, and amyloid β (Aβ)1-40 secreted into the medium were increased at the culture temperature of 37.5 °C compared to 35.0 °C. In short-term culture experiments, the secretion of Aβ1-40 observed in cataracts was increased at 37.5 °C compared to 35.0 °C, suggesting that the long-term exposure to a high-temperature environment may increase the risk of cataracts.

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