scholarly journals A numerical study of aerosol influence on mixed-phase stratiform clouds through modulation of the liquid phase

2013 ◽  
Vol 13 (4) ◽  
pp. 1733-1749 ◽  
Author(s):  
G. de Boer ◽  
T. Hashino ◽  
G. J. Tripoli ◽  
E. W. Eloranta
Keyword(s):  
Liquid Phase ◽  
Mass Fraction ◽  
Freezing Point ◽  
Numerical Study ◽  
Liquid Droplet ◽  
Number Concentration ◽  
Mixed Phase ◽  
Large Variability ◽  
Stratiform Clouds ◽  
Aerosol Properties

Abstract. Numerical simulations were carried out in a high-resolution two-dimensional framework to increase our understanding of aerosol indirect effects in mixed-phase stratiform clouds. Aerosol characteristics explored include insoluble particle type, soluble mass fraction, influence of aerosol-induced freezing point depression and influence of aerosol number concentration. Simulations were analyzed with a focus on the processes related to liquid phase microphysics, and ice formation was limited to droplet freezing. Of the aerosol properties investigated, aerosol insoluble mass type and its associated freezing efficiency was found to be most relevant to cloud lifetime. Secondary effects from aerosol soluble mass fraction and number concentration also alter cloud characteristics and lifetime. These alterations occur via various mechanisms, including changes to the amount of nucleated ice, influence on liquid phase precipitation and ice riming rates, and changes to liquid droplet nucleation and growth rates. Alteration of the aerosol properties in simulations with identical initial and boundary conditions results in large variability in simulated cloud thickness and lifetime, ranging from rapid and complete glaciation of liquid to the production of long-lived, thick stratiform mixed-phase cloud.

scholarly journals A numerical study of aerosol influence on mixed-phase stratiform clouds through modulation of the liquid phase

2012 ◽  
Vol 12 (8) ◽  
pp. 22059-22101
Author(s):  
G. de Boer ◽  
T. Hashino ◽  
G. J. Tripoli ◽  
E. W. Eloranta
Keyword(s):  
Liquid Phase ◽  
Mass Fraction ◽  
Freezing Point ◽  
Numerical Study ◽  
Liquid Droplet ◽  
Number Concentration ◽  
Mixed Phase ◽  
Droplet Growth ◽  
Large Variability ◽  
Stratiform Clouds

Abstract. Numerical simulations were carried out in a high-resolution two dimensional framework to increase our understanding of aerosol indirect effects in mixed-phase stratiform clouds. Aerosol characteristics explored include insoluble particle type, soluble mass fraction, the influence of aerosol-induced freezing point depression and the influence of aerosol number concentration. These experiments were completed with an emphasis on the liquid phase, with droplet freezing the mechanism for ice production. Of the aerosol properties investigated, aerosol insoluble mass type and its associated freezing efficiency was found to be most relevant to cloud lifetime. Secondary effects from aerosol soluble mass fraction and number concentration also alter cloud characteristics and lifetime. These alterations occur via various mechanisms, including changes to the amount of nucleated ice, influence on liquid phase precipitation and ice riming rates, and changes to liquid droplet growth rates. Simulation of the same environment leads to large variability of cloud thickness and lifetime, ranging from rapid and complete glaciation of the cloud to the production of a long-lived, thick stratiform mixed-phase cloud. In the end, these processes are summarized into a diagram that includes internal feedback loops that act within the cloud system.

The influence of different types of milking units on milk quality and safety

2019 ◽  
pp. 118-125
Author(s):  
A. Vovkohon ◽  
V. Nadtochiy ◽  
G. Kalinina ◽  
O. Hrebelnyk ◽  
N. Fedoruk ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Dry Matter ◽  
Freezing Point ◽  
Titratable Acidity ◽  
Petri Dish ◽  
Milk Quality ◽  
Quality And Safety ◽  
Protein Mass ◽  
Seeding Method ◽  
Conductivity Increase

The article highlights comparative research results of milk quality indices obtained from the milking in specialized milking halls with such milking units as «Parallel», «Carousel» or in stalls with the milking unit «Molokoprovid». The fat and protein mass fraction, dry matter and fat-free dry matter, density, titratable and active acidity, heat resistance and freezing point have been determined according to the accepted techniques. The electrical conductivity of milk has been determined by using the analytical device MD-20 MAS-D-TEC. The total amount of milk bacteria has been determined by reductase reduction test and by seeding method in Petri dish. The milk quality has been investigated by the fermentation and rennet fermentation tests. The higher indices of the fat mass fraction, the protein mass fraction and the dry substance concentration of milk, obtained in specialized milking halls, have been established. This is not statistically significant. Milk, obtained from the milking unit «Molokoprovid», has higher index of titratable acidity, lower thermal stability in comparison with milk, obtained from specialized milking halls with milking units «Parallel» and «Carousel». It has been determined that there is the bacteria insemination increase in milk received from milking cows in stalls in comparison with milk, obtained from milking in specialized halls. Milk, obtained from the milking unit «Carousel», indicates the subclinical form of mastitis in cows or «Carousel» operation violationif there is in 1,8 mS/cm conductivity increase above average index 4,6 mS/cm. Key words: technology, quality and safety of milk, milking, milking unit, milking hall, bacterial insemination.

A Numerical Study of the Development of Convective Motion in a Bottom Heated Square Enclosure Containing Ice and Water

1999 ◽  
Author(s):  
P. H. Oosthuizen
Keyword(s):  
Wall Temperature ◽  
Freezing Point ◽  
Numerical Study ◽  
Convective Motion ◽  
Lower Surface ◽  
Uniform Temperature ◽  
Density Maximum ◽  
Square Enclosure ◽  
Finite Element Procedure ◽  
Lower Surface Temperature

Abstract A numerical study of the steady state flow in a square enclosure with two vertical walls which are adiabatic and with two horizontal isothermal walls has been undertaken. The enclosure contains water and the upper wall is maintained at a uniform temperature that is below the freezing point of water while the lower wall is maintained at a uniform temperature that is above the freezing point of water. The upper portion of the enclosure is thus filled with ice and the lower portion is filled with water. The conditions considered in the present study are such there can be significant natural convection in the water and the effect of the density maximum that exists in the water at approximately 4°C can have a significant effect on this flow. The main aim of the study was to determine how far above 4°C the hot wall temperature can be before significant convective motion develops in the water. The governing equations have been expressed in dimensionless form and solved using a finite element procedure. The effect of the various governing parameters on the mean Nusselt number has mainly been considered and the effect of the lower surface temperature has, in particular, been studied. The results obtained, which indicate that convective motion does not occur until the lower hot wall temperature is well above the maximum density temperature, can be used to determine the actual hot wall temperature at which significant convective motion develops.

The ice nucleating ability of macromolecules in immersion freezing decreases in the presence of salts: Implications for freezing point depression calculations

2021 ◽  
Author(s):  
Jon F. Went ◽  
Jeanette D. Wheeler ◽  
François J. Peaudecerf ◽  
Nadine Borduas-Dedekind
Keyword(s):  
Sea Water ◽  
Freezing Point ◽  
Pure Water ◽  
Salt Content ◽  
Mixed Phase ◽  
Cloud Formation ◽  
Sea Spray ◽  
Freezing Point Depression ◽  
Immersion Freezing ◽  
Mixed Phase Clouds

<p>Cloud formation represents a large uncertainty in current climate predictions. In particular, ice in mixed-phase clouds requires the presence of ice nucleating particles (INPs) or ice nucleating macromolecules (INMs). An influential population of INPs has been proposed to be organic sea spray aerosols in otherwise pristine ocean air. However, the interactions between INMs present in sea water and their freezing behavior under atmospheric immersion freezing conditions warrants further research to constrain the role of sea spray aerosols on cloud formation. Indeed, salt is known to lower the freezing temperature of water, through a process called freezing point depression (FPD). Yet, current FPD corrections are solely based on the salt content and assume that the INMs’ ice nucleation abilities are identical with and without salt. Thus, we measured the effect of salt content on the ice nucleating ability of INMs, known to be associated with marine phytoplankton, in immersion freezing experiments in the Freezing Ice Nuclei Counter (FINC) (Miller et al., AMTD, 2020). We measured eight INMs, namely taurine, isethionate, xylose, mannitol, dextran, laminarin, and xanthan as INMs in pure water at temperatures relevant for mixed-phase clouds (e.g. 50% activated fraction at temperatures above –23 °C at 10 mM concentration). Subsequently, INMs were analyzed in artificial sea water containing 36 g salt L<sup>-1</sup>. Most INMs, except laminarin and xanthan, showed a loss of ice activity in artificial sea water compared to pure water, even after FPD correction. Based on our results, we hypothesize sea salt has an inhibitory effect on the ice activity of INMs. This effect influences our understanding of how INMs nucleate ice as well as challenges our use of FPD correction and subsequent extrapolation to ice activity under mixed-phase cloud conditions.</p>

scholarly journals Fuel and oxygen harvesting from Martian regolithic brine

2020 ◽  
Vol 117 (50) ◽  
pp. 31685-31689
Author(s):  
Pralay Gayen ◽  
Shrihari Sankarasubramanian ◽  
Vijay K. Ramani
Keyword(s):  
Liquid Phase ◽  
Production Rate ◽  
Resource Utilization ◽  
Life Support ◽  
Water Cycle ◽  
Freezing Point ◽  
Input Power ◽  
Fuel Production ◽  
The Phoenix

NASA’s current mandate is to land humans on Mars by 2033. Here, we demonstrate an approach to produce ultrapure H2 and O2 from liquid-phase Martian regolithic brine at ∼−36 °C. Utilizing a Pb2Ru2O7−δ pyrochlore O2-evolution electrocatalyst and a Pt/C H2-evolution electrocatalyst, we demonstrate a brine electrolyzer with >25× the O2 production rate of the Mars Oxygen In Situ Resource Utilization Experiment (MOXIE) from NASA’s Mars 2020 mission for the same input power under Martian terrestrial conditions. Given the Phoenix lander’s observation of an active water cycle on Mars and the extensive presence of perchlorate salts that depress water’s freezing point to ∼−60 °C, our approach provides a unique pathway to life-support and fuel production for future human missions to Mars.

scholarly journals Long-lifetime ice particles in mixed-phase stratiform clouds: Quasi-steady and recycled growth

2015 ◽  
Vol 120 (22) ◽  
pp. 11,617-11,635 ◽  
Author(s):  
Fan Yang ◽  
Mikhail Ovchinnikov ◽  
Raymond A. Shaw
Keyword(s):  
Mixed Phase ◽  
Ice Particles ◽  
Stratiform Clouds ◽  
Long Lifetime

scholarly journals Numerical study of the greenhouse solar drying of olive mill wastewater under different conditions

2020 ◽  
Vol 12 (4) ◽  
pp. 168781401988974 ◽  
Author(s):  
Chaima Bouraoui ◽  
Fayçal Ben Nejma
Keyword(s):  
Mass Fraction ◽  
Numerical Study ◽  
Meteorological Conditions ◽  
Olive Mill Wastewater ◽  
Comsol Multiphysics ◽  
Solar Drying ◽  
Drying Process ◽  
After Hours ◽  
Vapor Mass ◽  
Olive Mill

The aim of this work is to develop thermal modeling of the olive mill wastewater drying process in a greenhouse solar dryer. A configuration was thus proposed and simulated using the commercial software COMSOL Multiphysics in order to solve the conservation equations governing our problem. The resulting simulations are used to evaluate the temperature, velocity, and vapor mass fraction distributions after hours of sunshine and to provide a quantification of the drying process. The influence of the greenhouse effect on the drying kinetics is highlighted by comparing to open sun-drying results. The effect of some greenhouse geometric characteristics and external meteorological conditions are studied.

Three-Dimensional Numerical Study on Pool Stratification Behavior in Molten Corium-Concrete Interaction (MCCI) With MPS Method

2018 ◽  
Author(s):  
Xin Li ◽  
Ikken Sato ◽  
Akifumi Yamaji ◽  
Guangtao Duan
Keyword(s):  
Liquid Phase ◽  
Phase Change ◽  
Molten Pool ◽  
Numerical Study ◽  
Three Dimensional ◽  
Metallic Phase ◽  
Severe Accident ◽  
Mps Method ◽  
Solid Liquid ◽  
Concrete Interface

Molten corium-concrete interaction (MCCI) is an important ex-vessel phenomenon that could happen during the late phase of a hypothetical severe accident in a light water reactor. When the molten corium, which is generally comprised of UO2, ZrO2 and metals such as zircalloy and stainless steel, is discharged into a dry reactor cavity, a stratified molten pool configuration with two immiscible oxidic and metallic phases can be expected to form and lead to MCCI. Compared to a homogenous oxidic molten pool configuration, the metallic phase in the stratified molten pool might influence the crust formation on the corium-concrete interface and consequently cause different concrete ablation behavior to evaluate MCCI progression concerning containment failure. In terms of this issue, past experimental studies, such as COMET-L, VULCANO VBS and MOCKA test series, have been carried out to investigate the influence of such oxidic and metallic stratified pool configuration on MCCI. The experimental results have shown that the metallic phase can have a significant impact on the axial and radial ablation kinetics that could influence the ablation patterns of reactor pit. As regards numerical studies, past numerical modeling of MCCI was generally based on Eulerian methods and simplified empirical approach to simulate solid/liquid phase change and evolving of corium/crust/concrete interface. Such modeling might be efficient but have shown deficiencies and inadequacies due to its Eulerian and empirical nature, which has suggested a necessity to seek for a more mechanistic approach for modeling of MCCI. In this sense, Moving Particle Semi-implicit (MPS) method is considered suitable for MCCI analysis for its advantages of tracking interfaces and modeling phase change accurately as a Lagrangian particle method. In the present study, a three-dimensional (3-D) numerical study has been performed to simulate COMET-L3 test carried out by KIT with a stratified molten pool configuration of simulant materials with improved MPS method. Solid/liquid phase change was simulated with types of solid and liquid particles with thermal and physical properties including temperature and solid fraction, which enabled tracking of the solid/liquid status of each particle to achieve accurate free surface and corium/crust/concrete interface capturing. The heat transfer between corium/crust/concrete was modeled with heat conduction between particles. Moreover, the potential influence of the siliceous aggregates was also investigated by setting up two different case studies since there was previous study indicating that siliceous aggregates in siliceous concrete might contribute to different axial and radial concrete ablation rates. The simulation results have indicated that metal melt as corium in MCCI can have completely different characteristics regarding concrete ablation pattern from that of oxidic corium, which needs to be taken into consideration when assessing the containment melt-through time in severe accident management.

Prediction of ash flow temperature based on liquid phase mass fraction by FactSage

2020 ◽  
Vol 93 (6) ◽  
pp. 2228-2231
Author(s):  
Yang Li ◽  
Fenghai Li ◽  
Mingjie Ma ◽  
Bing Yu ◽  
Chaoyue Zhao ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Mass Fraction ◽  
Flow Temperature

Numerical and Experimental Study of the Evaporation and Solid Layer Formation of a Bi-Component Droplet Under Various Drying Conditions

2014 ◽  
Author(s):  
Holger Grosshans ◽  
Matthias Griesing ◽  
Srikanth R. Gopireddy ◽  
Werner Pauer ◽  
Hans-Ulrich Moritz ◽  
...  
Keyword(s):  
Droplet Size ◽  
Mass Fraction ◽  
Numerical Study ◽  
Droplet Evaporation ◽  
Droplet Surface ◽  
Parameter Study ◽  
Layer Formation ◽  
Gas Temperature ◽  
Solid Layer ◽  
Initial Droplet

This paper presents a combined experimental and numerical study of the evaporation and solid layer formation of a single bi-component mannitol-water droplet in air. For spherically symmetric droplets, the problem is described mathematically by the unsteady, one-dimensional conservation equations of mass and energy. The effect of the formation of a solid layer at the droplet surface on the droplet evaporation and thermal diffusion rate is included in the present approach. The simulations are validated by comparison with experiments using acoustically levitated droplets. The study includes initial droplet diameters varying from 350 to 450 μm, gas temperatures ranging from 80 to 120 °C, and the initial mannitol mass fraction inside the droplet varies from 0.05 to 0.15. The numerical results are analyzed to identify the occurrence of solid layer formation, and the temporal evolutions of both the droplet size and mass are presented. A parameter study of the initial gas temperature, the initial droplet size, and the initial mannitol mass fraction inside the droplet on droplet evaporation and solid layer formation is presented. The present model accurately captures the initial stages of droplet drying under all conditions investigated.

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