Two cloud-scale experiments with two different ice-phase schemes were carried out for a precipitation event that occurred in eastern China in 2005.The results were analyzed to examine the influences of the change of i...Two cloud-scale experiments with two different ice-phase schemes were carried out for a precipitation event that occurred in eastern China in 2005.The results were analyzed to examine the influences of the change of ice-particle mass and radius on hydrometeors,internal energy,and kinetic energy,as well as the primary factors responsible.It was found that the ice content increases notably and the snow content decreases due to the change.This is the consequence of the modulation of cloud microphysical processes.In particular,the Bergeron process and the accretion of snow and cloud ice are markedly influenced.The differences of internal energy and kinetic energy between the two experiments are caused by adjustments to pressure-flux divergence,the coupling of temperature and divergence,and gravitational work,and the reason is that these three factors result in differences of local changes of internal and kinetic energy.展开更多
Numerical models of trajectories of small aerosol spheres relative to oblate spheroids were used to determine ice crystal scavenging efficiencies. The models included the effects of aerodynamic flow about the ice part...Numerical models of trajectories of small aerosol spheres relative to oblate spheroids were used to determine ice crystal scavenging efficiencies. The models included the effects of aerodynamic flow about the ice particle, gravity, aerosol particle inertia and drag and electrostatic effects. Two electric configurations of the ice particle were investigated in detail. The first applied a net charge to the ice particle, of magnitude equal to the mean thunderstorm charge distribution, while the second applied a charge distribution, with no net charge, to the ice particle to model the electric multipole charge distribution. The results show that growing ice crystals with electric multipoles are better scavengers than single ice crystals with net thunderstorm charges, especially in the Greenfield gap (0.1 to 1.0 um), and that larger single crystals are better scavengers than smaller single crystals. The results also show that the low density ice crystals are more effective scavengers with net charges than they are with charge distribution.展开更多
In order to understand the dominant factors of the physical properties of ice in ice thermodynamics and mechanics, in-situ observations of ice growth and decay processes were carried out. Two samplings were conducted ...In order to understand the dominant factors of the physical properties of ice in ice thermodynamics and mechanics, in-situ observations of ice growth and decay processes were carried out. Two samplings were conducted in the fast and steady ice growth stages. Ice pieces were used to observe ice crystals and gas bubbles in ice, and to measure the ice density. Vertical profiles of the type and size of ice crystals, shape and size of gas bubbles, and gas bubble content, as well as the ice density, were obtained. The results show that the upper layer of the ice pieces is granular ice and the lower layer is columnar ice; the average crystal size increases with the ice depth and remains steady in the fast and steady ice growth stages; the shape of gas bubbles in the upper layer of ice pieces is spherical with higher total content, and the shape in the middle and lower layers is cylinder with lower total content; the gas bubble size and content vary with the ice growth stage; and the ice density decreases with the increase of the gas bubble content.展开更多
This paper investigates the coupling characteristics of motion and heat transfer between airflow and ice crystals in a single-stage compressor.The motion and phase transition process of ice crystal particles were mode...This paper investigates the coupling characteristics of motion and heat transfer between airflow and ice crystals in a single-stage compressor.The motion and phase transition process of ice crystal particles were modeled using the Eulerian trajectory method and validated.The heat and mass transfer processes between airflows in compressor and ice crystals were simulated and analyzed.The melting ratio,catching efficiency,and sticking efficiency of ice crystals were obtained,as well as variations in temperature and humidity ratio in the airflow due to ice crystal phase change.The results show that the ice crystals sticking to blades in the single-stage compressor account for 10.35%of the impact mass flow rate.Additionally,the presence of ice crystals causes a 0.466 K decrease in the airflow temperature and a 0.114 g/kg(a)increase in the humidity ratio.The theoretical model and calculation method provide strong support for future ice crystal icing simulations and engine operation research.展开更多
The melting process of ice crystal particles has a significant effect on weather forecasting and global climate.Millimeter waveband is an excellent frequency range for exploring the optical characteristics of ice crys...The melting process of ice crystal particles has a significant effect on weather forecasting and global climate.Millimeter waveband is an excellent frequency range for exploring the optical characteristics of ice crystal particles.In this study,a new nonspherical and inhomogeneous ice crystal particle model is built based on the melting process of ice crystal particles.The single-scattering characteristics of ice crystal particles with different frequencies,sizes,shapes and ice crystal content(ICC)are investigated using the discrete dipole approximation(DDA)method.The results show that the single-scattering characteristics of ice crystal particles are closely related to the equivalent radius,frequency,morphology and mixing state.The single-scattering properties of the particles change regularly with the melting process of the ice crystal particles.Specifically,in the early stage of the ice crystal particle melting process,the single-scattering characteristics of ice crystal particles change significantly.With further melting,the change in the single-scattering characteristics of ice crystal particles gradually slows down when the ICC is less than 0.5.The results also show that in the early stage of the melting process,the shape of the ice crystal particles has a huge influence on the single-scattering characteristics of the particles,and in the late stage of the melting process,the single-scattering characteristics of the ice crystal particles are basically independent of the morphology of the ice crystal nuclei.This means that the influence of the morphology of the ice crystal nuclei needs to be considered in phases when simulating the scattering characteristics of the melting ice crystal particles.In summary,the results of this study should improve our understanding of the effect of size parameter,morphology and mixing state on the millimeter-wave scattering characteristics of ice clouds during the melting process and provide a reference for the remote sensing inversion of ice cloud microphysical characteristics.展开更多
The work presented previously by the authors(Cai and Liou,1982)has been extended in this paper. By making use of our improved model the calculations on scattering phase matrices of hexagonal prism ice crystals(HPIC)ha...The work presented previously by the authors(Cai and Liou,1982)has been extended in this paper. By making use of our improved model the calculations on scattering phase matrices of hexagonal prism ice crystals(HPIC)have been conducted for monodisperse and polydisperse systems.Compared with the model of Cai and Liou,the required computational quantity is decreased by about two orders of magni- tude and the errors of results are less for the new model.Meanwhile,the scattering phase matrices of triangular pyramid ice crystals(TPIC)are also computed in the paper,and the comparison between the scatterings of the two forms of ice crystals is performed.展开更多
The role of phoretic forces in the identification of particles acting as ice nuclei in mixed phase cloud is discussed. A method used to identify the effective ice nucleating particles is to sample ice crystals, which ...The role of phoretic forces in the identification of particles acting as ice nuclei in mixed phase cloud is discussed. A method used to identify the effective ice nucleating particles is to sample ice crystals, which are afterwards sublimated, and to examine the particles remaining after evaporation. The procedure takes into account only crystal with a maximum diameter of 20 μm, by assuming that small crystals do not scavenge aerosol during growth, and therefore that crystals contain only the effective nucleating particles. This assumption is questionable, however, as experiments have shown that even small ice crystals can scavenge aerosol. Another approach has been to compare the number and elemental composition of residual particles in small ice crystals and of aerosol near the cloud. By considering as example soot and black carbon aerosol, contradictory conclusions on their importance in the processes of ice nucleation have been reported in the literature. We suggest that, in addition to physico-chemical properties of soot/carbon aerosol particles, even the microphysical and environmental parameters involved in the transition of aerosol from gas phase to ice crystals in cloud should be considered. The contribution of phoretic forces should also be considered. After initial growth ice crystals can continue to grow by water vapour diffusion. Laboratory experiments confirm the contribution of diffusiophoresis with Stefan flow in the scavenging by snow crystals up to 3 mm in diameter. The particle scavenging efficiency of snow crystals is related to crystalline shape and depends on air relative humidity and temperature.展开更多
A new technique for ice slurry production was explored. Multiple small water-drops were formed in another immiscible chilled liquid by a single-nozzled atomizer and frozen in the fluidized bed by direct contact heat t...A new technique for ice slurry production was explored. Multiple small water-drops were formed in another immiscible chilled liquid by a single-nozzled atomizer and frozen in the fluidized bed by direct contact heat transfer. Experiments were conducted to investigate the dynamic behaviors of the ice crystal making system. The results demonstrate that the ice crystals could be produced continuously and stably in the vertical bed with the circulating coolant of initial temperature below -5℃. The size distribution of the ice crystals appears non-uniform, but is more similar and more uniform at lower oil flow rate. The mean ice crystal size rests seriously with the jet velocity and the oil flow rate. It decreases with decreasing the oil flow rate, and reaches the maximum at an intermediate jet velocity at about 16.5 m.s y. The ice crystal size is also closely related to the phenomenon of drop-coalescing, which can be alleviated considerably by reducing the flow rate or lowering the temperature of the carrier oil. However, optimization of liquid-liquid atomization is a more effective approach to produce fine ice crystals of desired size.展开更多
Freeze concentration has great potential in treating wastewaters containing soluble pollutions. It is important for freeze concentration process to produce ice crystals with large size and high purity. In this work ra...Freeze concentration has great potential in treating wastewaters containing soluble pollutions. It is important for freeze concentration process to produce ice crystals with large size and high purity. In this work raw urines of 4660 -7914 mg/L in COD, 512. 71 -872. 41 mg/L in NH3 -N and 22600 -28800 μs/cm in electric conductivity were studied. Urines were frozen by a digital refrigerated circulator bath. Ice crystals were purified by ice-water steep and vacuum filtration. The COD, NH3 - N, and electric conductivity levels of the melted ices were measured to reflect ice crystal purity. Effects of coolant temperature, ice crystal shape, initial solution temperature, solution concentration, ice seeding, re-crystallization process and crystallization time on ice crystal purity were analyzed. The results show that an appropriate coolant temperature, suspended ice crystals, an initial solution temperature of about 6 ℃, introduction of seed ice, addition of re-crystallization process, and crystallization time of less than 30 min axe in favor of producing ice crystals with high purity. Under such conditions, more than 99 percent of inorganic salts, COD and NH3 - N sources in raw urine could he removed.展开更多
In this study, the effects of key ice microphysical processes on the pre-summer heavy rainfall over southern China during 3-8 June 2008 were investigated. A series of two-dimensional sensitivity cloud-resolving model ...In this study, the effects of key ice microphysical processes on the pre-summer heavy rainfall over southern China during 3-8 June 2008 were investigated. A series of two-dimensional sensitivity cloud-resolving model simulations were forced with zonally uniform vertical velocity, zonal wind, horizontal temperature, and water vapor advection data from the National Centers for Environmental Prediction （NCEP）/Global Data Assimilation System （GDAS）. The effects of key ice microphysical processes on the responses of rainfall to large-scale forcing were analyzed by comparing two sensitivity experiments with a control experiment. In one sensitivity experiment, ice crystal radius, associated with depositional growth of snow from cloud ice, was reduced from 100 #m in the control experiment to 50 #m, and in the other sensitivity experiment the efficiency of the growth of graupel from the accretion of snow was reduced to 50~ from 100% in the control experiment. The results show that the domain-mean rainfall responses to these ice microphysical processes are stronger during the decay phase than during the onset and mature phases. During the decay phase, the increased mean rain rate resulting from the decrease in ice crystal radius is associated with the enhanced mean local atmospheric drying, the increased mean local hydrometeor loss, and the suppressed mean water vapor divergence. The increased mean rain rate caused by the reduction in accretion efficiency is related to the reduced mean water vapor divergence and the enhanced mean local hydrometeor loss.展开更多
Aerogels are special porous materials with low thermal conductivity,light weight,high energy absorption rate and large surface area,which have been applied in many fields.However,controlling the aerogel microstructure...Aerogels are special porous materials with low thermal conductivity,light weight,high energy absorption rate and large surface area,which have been applied in many fields.However,controlling the aerogel microstructure remains an academic challenge.Herein,by employing graphene oxide(GO)as the aerogel skeleton and utilizing poly(vinyl alcohol)(PVA)to regulate the ice crystal growth,we elucidate the relationships between the physicochemical properties of GO/PVA aerogel precursors and the nucleation and growth of ice crystals by using an ice-templating method.We demonstrate that due to the hydrogen bond formed between PVA and water molecules,resulting in the initial crystallization temperature being reduced from-12.60℃(GO/PVA-0.01)to-16.21℃(GO/PVA-0.1).Meanwhile,the strong hydrogen bond between PVA and GO limits the diffusion of water molecules,thereby inhibiting the growth of ice crystals,decreasing the pore size of the GO/PVA aerogel from 9.96 nm(GO/PVA-0.01)to 7.19 nm(GO/PVA-0.3),and thus the compressive strength of the aerogel increases from 0.045 MPa to 0.13MPa.Overall,the finding of this study can be extended to other aerogel precursors,and exhibit important scientific value and practical significance for the preparation of aerogel materials with highly controllable structures and performances.展开更多
In winter, spring and summer, the rhizome of wild Elytrzgia repens of Heilongjiang Province was selected to extract the soluble which whole protein and the apoplastic protein, and analyzed by SDS-PAGE. The result indi...In winter, spring and summer, the rhizome of wild Elytrzgia repens of Heilongjiang Province was selected to extract the soluble which whole protein and the apoplastic protein, and analyzed by SDS-PAGE. The result indicated that there were two specific polypeptides in two types protein from winter; their relative molecular weight were identified as 52 ku and 26 ku by analyzing software; the apoplastic protein from winter had the ability of modifing the growth of ice crystal which appeared hexagonal in shape observed with the phase-contrast photomicroscope. So the apoplastic protein from winter has the antifreeze characters and the 52 ku protein is more likely the antifreeze protein展开更多
During the winter and spring of 2006, we investigated the sea ice physics and marine biology in the northwest Weddell Sea, Antarctica aboard R/V Polarstern. We determined the texture of each ice core and 71 ice crysta...During the winter and spring of 2006, we investigated the sea ice physics and marine biology in the northwest Weddell Sea, Antarctica aboard R/V Polarstern. We determined the texture of each ice core and 71 ice crystal thin sections from 27 ice cores. We analyzed 393 ice cores, their temperatures, 348 block density and salinity samples,and 311 chlorophyll a（Chl a） and phaeophytin samples along the cruise route during the investigation. Based on the vertical distributions of 302 groups of data for the ice porosity and Chl a content in the ice at the same position, we obtained new evidence that ice physical parameters influence the Chl a content in ice. We collected snow and ice thickness data, and established the effects of the snow and ice thickness on the Chl a blooms under the ice, as well as the relationships between the activity of ice algae cells and the brine volume in ice according to the principle of environmental control of the ecological balance. We determined the upper limits for Chl a in the brine volume of granular and columnar ice in the Antarctica, thereby demonstrating the effects of ice crystals on brine drainage, and the contributions of the physical properties of sea ice to Chl a blooms near the ice bottom and on the ice-water interface in the austral spring. Moreover, we found that the physical properties of sea ice affect ice algae and they are key control elements that modulate marine phytoplankton blooms in the ice-covered waters around Antarctica.展开更多
Depositional growth of ice crystal is one of the major processes for development of precipitation systems and can be represented by depositional growth of cloud ice from cloud water(P_(IDW)) and depositional growth of...Depositional growth of ice crystal is one of the major processes for development of precipitation systems and can be represented by depositional growth of cloud ice from cloud water(P_(IDW)) and depositional growth of snow from cloud ice(P_(SFI)) in cloud-resolving model. Four parameterization schemes are analyzed in the cloud-resolving model simulations of four rainfall cases over the tropics and midlatitudes. The comparison of time and model domain mean data shows that Shen's scheme produces the closest rainfall simulation to the observation. Compared to Zeng's scheme,Shen's scheme improves the mean rain-rate simulation significantly through the dramatic decrease in depositional growth of cloud ice from cloud water. Compared to other schemes, Shen's scheme produces the better rainfall simulation via the reduction in the mean rain rate associated with the enhanced gain of cloud water and ice.展开更多
The diffraction angular distributions are calculated for different ice crystals (e.g,solid and hollow hexagonal columns,solid plates and single hexagonal bullet) randomly oriented in space,based on the theory of Cai a...The diffraction angular distributions are calculated for different ice crystals (e.g,solid and hollow hexagonal columns,solid plates and single hexagonal bullet) randomly oriented in space,based on the theory of Cai and Liou.Results of solid column and plate are compared with those from formulas of Wendling et al and Liou.The resull comparison shows that all three procedures discussed in this paper have good agreement.After considering the coin putation time and comparison results,it is suggested that the formula of Wendling et al.can be used to calculate the solid column diffraction,and the formula of Liou can be used to calculate the plate diffraction.The comparison also shows that the diffraction results of solid columu,hollow column and single bullet ice particles randomly oriented in space are very close.展开更多
aquatic product, known as one of the good resources for white meat, has been widely accepted by the consumers due to its high protein, low fat, especially low cholesterol. With the fast development of living standards...aquatic product, known as one of the good resources for white meat, has been widely accepted by the consumers due to its high protein, low fat, especially low cholesterol. With the fast development of living standards around the world, the consumer demands for high quality, nutrition, safety and freshness of ifshery food are increasing. Thus, high efifcient preservation technologies for aquatic products become particularly important. Superchilling is one of the controlled-temperature preservation technologies for seafood. Aquatic products can be kept in better quality under superchilling conditions. This review introduced the principle and development of superchilling process, mainly focusing on research progresses and technical dififculties of superchilling. The growth mechanism of ice crystals and the feasibility of application of computational lfuid dynamics in analyzing the temperatures variation and ice crystals during superchilling progress were also discussed, which will provide theoretical foundation for its improvement and application.展开更多
Cryopreservation is a promising technique for the long-term storage of skin.However,the formation of ice crystals during cryopreservation unavoidably damages skin structure and functionality.Currently,the lack of thor...Cryopreservation is a promising technique for the long-term storage of skin.However,the formation of ice crystals during cryopreservation unavoidably damages skin structure and functionality.Currently,the lack of thorough and systematic investigation into the internal mechanisms of skin cryoinjury obstructs the advancement of cryopreservation technology.In this study,we identified 3 primary contributors to skin cryoinjury:interfacial ice nucleation,stress accumulation,and thermal stress escalation.We emphasized the paramount role of interfacial ice nucleation in provoking ice growth within the skin during the cooling process.This progress subsequently leads to stress accumulation within the skin.During the rewarming process,the brittleness of skin,previously subjected to freezing,experienced a marked increase in thermal stress due to ice recrystallization.Based on these insights,we developed a novel zwitterionic betaine-based solution formulation designed for cryopreservation skin.This cryoprotective agent formulation exhibited superior capability in lowering ice nucleation temperatures and inhibiting ice formation at interfaces,while also facilitating the growth of smooth and rounded ice crystals compared to sharp-edged and cornered crystals formed in aqueous solutions.As a result,we successfully achieved prolonged cryopreservation of the skin for at least 6 months,while preserving 98.7%of structural integrity and 94.7%of Young’s modulus.This work provides valuable insights into the mechanisms of ice crystal damage during organ cryopreservation and profoundly impacts the field of organ transplantation and regenerative medicine.展开更多
This study presents a novel design for a spiral finned crystallizer which is the primary element of progressive freeze concentration(PFC) system, which simplifies the setup of the conventional system. After the crysta...This study presents a novel design for a spiral finned crystallizer which is the primary element of progressive freeze concentration(PFC) system, which simplifies the setup of the conventional system. After the crystallizer has been designed, the research experiments have been conducted and evaluated through a thorough analysis of its performance by developing a mathematical model that can be used to predict the productivity of ice crystal at a range of coolant temperature. The model is developed based on the basic heat transfer equation, and by considering the solution's and the coolant's convective heat transfer coefficient(h) under the forced flow condition.The model's accuracy is verified by making comparison between the ice crystal mass' experimental value and the values predicted by the model. Consequently, the study found that the model helps in enhancing the PFC system.展开更多
The low temperature is an effective method for postharvest fruits preservation.However,the ice crystal nucleation caused by low temperature significantly decreases the quality of fruits.in this paper,the effects of al...The low temperature is an effective method for postharvest fruits preservation.However,the ice crystal nucleation caused by low temperature significantly decreases the quality of fruits.in this paper,the effects of alternating magnetic field(aMF)on the ice nucleation temperature of grape were investigated,and the aMF continued treatment and aMF intermittent treatment(20 Gs,60 Hz)assisted near-freezing temperature(aMct/aMit-NFt)were used to store grapes at(−2.5±0.2)℃.compared with the untreated group,aMF decreased the ice nucleation temperature of grape 1℃.Meanwhile,results demonstrated that aMct/aMit-NFt storage improved sensory properties and antioxidant capacity of grapes,with the overall effect of aMit treatment being the most favorable.after 9 days of storage,the color difference and polyphenol oxidase(PPo)activity of aMit treatment were reduced by 17%and 12%,respectively,compared with the untreated group,and it effectively slowed down malonaldehyde(MDa)accumulation.these conclusions show that aMct/aMit-NFt storage is an effective tool for prolonging the shelf life of grapes.展开更多
The ice forming rates p_i produced by supersonic flow have been measured in supercooled fog suspended in a cold chamber at temperatures of 0 to-12℃.It has been shown that the ice-forming rates are 10^(11)to 10^(12)cr...The ice forming rates p_i produced by supersonic flow have been measured in supercooled fog suspended in a cold chamber at temperatures of 0 to-12℃.It has been shown that the ice-forming rates are 10^(11)to 10^(12)crystals per gram of air at Mach numbers of 1.1 to 1.84 and total pressures below 6 atm,and that the ice-forming rates slowly increase with increasing Mach numbers and total pressures and with decreasing ambient temperatures.These results are theoretically consistent with the rules for expansion in supersonic flow. In review of mechanisms of ice crystal generation,authors propose that the homogeneous nucleation-freezing (condensation-freezing)of water vapor in supersonic flow be the dominant mechanism.In our opinion,supersonic flow, for artificial precipitation,could be expected to provide an economical,non-polluting and convenient technology,and suitable for the long-distance operation.The data obtained from our experiments indicate that it is feasible to develop a new technique for weather modification.展开更多
基金supported by the National Basic Research Program of China (Grant No.2013CB430105)the Key Program of the Chinese Academy of Sciences (Grant No.KZZD-EW-05)+2 种基金the Project of Chinese Academy of Meteorological Sciences (Grant No.2011LASW-B15)the Special Scientific Research Fund of Meteorological Public Welfare of the Ministry of Sciences and Technology (Grant No.GYHY200906004)and the National Natural Science Foundation of China (Grant Nos.41175060,41075098,and 41005005)
文摘Two cloud-scale experiments with two different ice-phase schemes were carried out for a precipitation event that occurred in eastern China in 2005.The results were analyzed to examine the influences of the change of ice-particle mass and radius on hydrometeors,internal energy,and kinetic energy,as well as the primary factors responsible.It was found that the ice content increases notably and the snow content decreases due to the change.This is the consequence of the modulation of cloud microphysical processes.In particular,the Bergeron process and the accretion of snow and cloud ice are markedly influenced.The differences of internal energy and kinetic energy between the two experiments are caused by adjustments to pressure-flux divergence,the coupling of temperature and divergence,and gravitational work,and the reason is that these three factors result in differences of local changes of internal and kinetic energy.
文摘Numerical models of trajectories of small aerosol spheres relative to oblate spheroids were used to determine ice crystal scavenging efficiencies. The models included the effects of aerodynamic flow about the ice particle, gravity, aerosol particle inertia and drag and electrostatic effects. Two electric configurations of the ice particle were investigated in detail. The first applied a net charge to the ice particle, of magnitude equal to the mean thunderstorm charge distribution, while the second applied a charge distribution, with no net charge, to the ice particle to model the electric multipole charge distribution. The results show that growing ice crystals with electric multipoles are better scavengers than single ice crystals with net thunderstorm charges, especially in the Greenfield gap (0.1 to 1.0 um), and that larger single crystals are better scavengers than smaller single crystals. The results also show that the low density ice crystals are more effective scavengers with net charges than they are with charge distribution.
基金supported by the National Natural Science Foundation of China (Grant No.50879008)the Open Fund of State Key Laboratory of Frozen Soil Engineering (Grant No. SKLFSE200904)+1 种基金the Vilho,Yrj and Kalle Visl Fund of the Finnish Academy of Sciences and Lettersthe Norwegian Research Council Project AMORA (Grant No.193592/S30)
文摘In order to understand the dominant factors of the physical properties of ice in ice thermodynamics and mechanics, in-situ observations of ice growth and decay processes were carried out. Two samplings were conducted in the fast and steady ice growth stages. Ice pieces were used to observe ice crystals and gas bubbles in ice, and to measure the ice density. Vertical profiles of the type and size of ice crystals, shape and size of gas bubbles, and gas bubble content, as well as the ice density, were obtained. The results show that the upper layer of the ice pieces is granular ice and the lower layer is columnar ice; the average crystal size increases with the ice depth and remains steady in the fast and steady ice growth stages; the shape of gas bubbles in the upper layer of ice pieces is spherical with higher total content, and the shape in the middle and lower layers is cylinder with lower total content; the gas bubble size and content vary with the ice growth stage; and the ice density decreases with the increase of the gas bubble content.
基金the Key Laboratory of Icing and Anti/De-icing of CARDC(IADL20210102)the National Natural Science Foundation of China(52272428)+1 种基金the Fundamental Research Funds for the Central Universities(YWF-22-L-732,YWF-23-SDHK-L-003)111 Center(B18002)for financial supports of this work.
文摘This paper investigates the coupling characteristics of motion and heat transfer between airflow and ice crystals in a single-stage compressor.The motion and phase transition process of ice crystal particles were modeled using the Eulerian trajectory method and validated.The heat and mass transfer processes between airflows in compressor and ice crystals were simulated and analyzed.The melting ratio,catching efficiency,and sticking efficiency of ice crystals were obtained,as well as variations in temperature and humidity ratio in the airflow due to ice crystal phase change.The results show that the ice crystals sticking to blades in the single-stage compressor account for 10.35%of the impact mass flow rate.Additionally,the presence of ice crystals causes a 0.466 K decrease in the airflow temperature and a 0.114 g/kg(a)increase in the humidity ratio.The theoretical model and calculation method provide strong support for future ice crystal icing simulations and engine operation research.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0706004)the Key Projects of Science and Technology Research of Henan Province(Grant No.222102320087)the Key Scientific Research Project of Colleges and Universities in Henan Province(Grant No.25B170004).
文摘The melting process of ice crystal particles has a significant effect on weather forecasting and global climate.Millimeter waveband is an excellent frequency range for exploring the optical characteristics of ice crystal particles.In this study,a new nonspherical and inhomogeneous ice crystal particle model is built based on the melting process of ice crystal particles.The single-scattering characteristics of ice crystal particles with different frequencies,sizes,shapes and ice crystal content(ICC)are investigated using the discrete dipole approximation(DDA)method.The results show that the single-scattering characteristics of ice crystal particles are closely related to the equivalent radius,frequency,morphology and mixing state.The single-scattering properties of the particles change regularly with the melting process of the ice crystal particles.Specifically,in the early stage of the ice crystal particle melting process,the single-scattering characteristics of ice crystal particles change significantly.With further melting,the change in the single-scattering characteristics of ice crystal particles gradually slows down when the ICC is less than 0.5.The results also show that in the early stage of the melting process,the shape of the ice crystal particles has a huge influence on the single-scattering characteristics of the particles,and in the late stage of the melting process,the single-scattering characteristics of the ice crystal particles are basically independent of the morphology of the ice crystal nuclei.This means that the influence of the morphology of the ice crystal nuclei needs to be considered in phases when simulating the scattering characteristics of the melting ice crystal particles.In summary,the results of this study should improve our understanding of the effect of size parameter,morphology and mixing state on the millimeter-wave scattering characteristics of ice clouds during the melting process and provide a reference for the remote sensing inversion of ice cloud microphysical characteristics.
文摘The work presented previously by the authors(Cai and Liou,1982)has been extended in this paper. By making use of our improved model the calculations on scattering phase matrices of hexagonal prism ice crystals(HPIC)have been conducted for monodisperse and polydisperse systems.Compared with the model of Cai and Liou,the required computational quantity is decreased by about two orders of magni- tude and the errors of results are less for the new model.Meanwhile,the scattering phase matrices of triangular pyramid ice crystals(TPIC)are also computed in the paper,and the comparison between the scatterings of the two forms of ice crystals is performed.
文摘The role of phoretic forces in the identification of particles acting as ice nuclei in mixed phase cloud is discussed. A method used to identify the effective ice nucleating particles is to sample ice crystals, which are afterwards sublimated, and to examine the particles remaining after evaporation. The procedure takes into account only crystal with a maximum diameter of 20 μm, by assuming that small crystals do not scavenge aerosol during growth, and therefore that crystals contain only the effective nucleating particles. This assumption is questionable, however, as experiments have shown that even small ice crystals can scavenge aerosol. Another approach has been to compare the number and elemental composition of residual particles in small ice crystals and of aerosol near the cloud. By considering as example soot and black carbon aerosol, contradictory conclusions on their importance in the processes of ice nucleation have been reported in the literature. We suggest that, in addition to physico-chemical properties of soot/carbon aerosol particles, even the microphysical and environmental parameters involved in the transition of aerosol from gas phase to ice crystals in cloud should be considered. The contribution of phoretic forces should also be considered. After initial growth ice crystals can continue to grow by water vapour diffusion. Laboratory experiments confirm the contribution of diffusiophoresis with Stefan flow in the scavenging by snow crystals up to 3 mm in diameter. The particle scavenging efficiency of snow crystals is related to crystalline shape and depends on air relative humidity and temperature.
基金the Specialized Research Fund for the Doctoral Program of Higher Education of China(20060286034)
文摘A new technique for ice slurry production was explored. Multiple small water-drops were formed in another immiscible chilled liquid by a single-nozzled atomizer and frozen in the fluidized bed by direct contact heat transfer. Experiments were conducted to investigate the dynamic behaviors of the ice crystal making system. The results demonstrate that the ice crystals could be produced continuously and stably in the vertical bed with the circulating coolant of initial temperature below -5℃. The size distribution of the ice crystals appears non-uniform, but is more similar and more uniform at lower oil flow rate. The mean ice crystal size rests seriously with the jet velocity and the oil flow rate. It decreases with decreasing the oil flow rate, and reaches the maximum at an intermediate jet velocity at about 16.5 m.s y. The ice crystal size is also closely related to the phenomenon of drop-coalescing, which can be alleviated considerably by reducing the flow rate or lowering the temperature of the carrier oil. However, optimization of liquid-liquid atomization is a more effective approach to produce fine ice crystals of desired size.
基金Sponsored by the High Technology Research and Development Programm of China(Grant No.2002AA743022).
文摘Freeze concentration has great potential in treating wastewaters containing soluble pollutions. It is important for freeze concentration process to produce ice crystals with large size and high purity. In this work raw urines of 4660 -7914 mg/L in COD, 512. 71 -872. 41 mg/L in NH3 -N and 22600 -28800 μs/cm in electric conductivity were studied. Urines were frozen by a digital refrigerated circulator bath. Ice crystals were purified by ice-water steep and vacuum filtration. The COD, NH3 - N, and electric conductivity levels of the melted ices were measured to reflect ice crystal purity. Effects of coolant temperature, ice crystal shape, initial solution temperature, solution concentration, ice seeding, re-crystallization process and crystallization time on ice crystal purity were analyzed. The results show that an appropriate coolant temperature, suspended ice crystals, an initial solution temperature of about 6 ℃, introduction of seed ice, addition of re-crystallization process, and crystallization time of less than 30 min axe in favor of producing ice crystals with high purity. Under such conditions, more than 99 percent of inorganic salts, COD and NH3 - N sources in raw urine could he removed.
基金supported by the National Key Basic Research and Development Project of China (Grant No. 2011CB403405)the National Natural Science Foundation of China (Grant Nos. 41075039 and 41175065)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘In this study, the effects of key ice microphysical processes on the pre-summer heavy rainfall over southern China during 3-8 June 2008 were investigated. A series of two-dimensional sensitivity cloud-resolving model simulations were forced with zonally uniform vertical velocity, zonal wind, horizontal temperature, and water vapor advection data from the National Centers for Environmental Prediction （NCEP）/Global Data Assimilation System （GDAS）. The effects of key ice microphysical processes on the responses of rainfall to large-scale forcing were analyzed by comparing two sensitivity experiments with a control experiment. In one sensitivity experiment, ice crystal radius, associated with depositional growth of snow from cloud ice, was reduced from 100 #m in the control experiment to 50 #m, and in the other sensitivity experiment the efficiency of the growth of graupel from the accretion of snow was reduced to 50~ from 100% in the control experiment. The results show that the domain-mean rainfall responses to these ice microphysical processes are stronger during the decay phase than during the onset and mature phases. During the decay phase, the increased mean rain rate resulting from the decrease in ice crystal radius is associated with the enhanced mean local atmospheric drying, the increased mean local hydrometeor loss, and the suppressed mean water vapor divergence. The increased mean rain rate caused by the reduction in accretion efficiency is related to the reduced mean water vapor divergence and the enhanced mean local hydrometeor loss.
基金financially supported by the National Natural Science Foundation of China(No.51873133)。
文摘Aerogels are special porous materials with low thermal conductivity,light weight,high energy absorption rate and large surface area,which have been applied in many fields.However,controlling the aerogel microstructure remains an academic challenge.Herein,by employing graphene oxide(GO)as the aerogel skeleton and utilizing poly(vinyl alcohol)(PVA)to regulate the ice crystal growth,we elucidate the relationships between the physicochemical properties of GO/PVA aerogel precursors and the nucleation and growth of ice crystals by using an ice-templating method.We demonstrate that due to the hydrogen bond formed between PVA and water molecules,resulting in the initial crystallization temperature being reduced from-12.60℃(GO/PVA-0.01)to-16.21℃(GO/PVA-0.1).Meanwhile,the strong hydrogen bond between PVA and GO limits the diffusion of water molecules,thereby inhibiting the growth of ice crystals,decreasing the pore size of the GO/PVA aerogel from 9.96 nm(GO/PVA-0.01)to 7.19 nm(GO/PVA-0.3),and thus the compressive strength of the aerogel increases from 0.045 MPa to 0.13MPa.Overall,the finding of this study can be extended to other aerogel precursors,and exhibit important scientific value and practical significance for the preparation of aerogel materials with highly controllable structures and performances.
基金Supported by Heilongjiang Province Science and Technology Key Project(GC04B115)
文摘In winter, spring and summer, the rhizome of wild Elytrzgia repens of Heilongjiang Province was selected to extract the soluble which whole protein and the apoplastic protein, and analyzed by SDS-PAGE. The result indicated that there were two specific polypeptides in two types protein from winter; their relative molecular weight were identified as 52 ku and 26 ku by analyzing software; the apoplastic protein from winter had the ability of modifing the growth of ice crystal which appeared hexagonal in shape observed with the phase-contrast photomicroscope. So the apoplastic protein from winter has the antifreeze characters and the 52 ku protein is more likely the antifreeze protein
基金The National Natural Science Foundation of China under contract Nos 51221961 and 41376186Chinese Arctic and Antarctic Administration for expedition and external cooperation foundations under contract No.IC201209the foundation of State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology,China under contract No.SL14-5-3
文摘During the winter and spring of 2006, we investigated the sea ice physics and marine biology in the northwest Weddell Sea, Antarctica aboard R/V Polarstern. We determined the texture of each ice core and 71 ice crystal thin sections from 27 ice cores. We analyzed 393 ice cores, their temperatures, 348 block density and salinity samples,and 311 chlorophyll a（Chl a） and phaeophytin samples along the cruise route during the investigation. Based on the vertical distributions of 302 groups of data for the ice porosity and Chl a content in the ice at the same position, we obtained new evidence that ice physical parameters influence the Chl a content in ice. We collected snow and ice thickness data, and established the effects of the snow and ice thickness on the Chl a blooms under the ice, as well as the relationships between the activity of ice algae cells and the brine volume in ice according to the principle of environmental control of the ecological balance. We determined the upper limits for Chl a in the brine volume of granular and columnar ice in the Antarctica, thereby demonstrating the effects of ice crystals on brine drainage, and the contributions of the physical properties of sea ice to Chl a blooms near the ice bottom and on the ice-water interface in the austral spring. Moreover, we found that the physical properties of sea ice affect ice algae and they are key control elements that modulate marine phytoplankton blooms in the ice-covered waters around Antarctica.
基金National Natural Science Foundation of China(41475039)National Key Basic Research and Development Project of China(2015CB953601)
文摘Depositional growth of ice crystal is one of the major processes for development of precipitation systems and can be represented by depositional growth of cloud ice from cloud water(P_(IDW)) and depositional growth of snow from cloud ice(P_(SFI)) in cloud-resolving model. Four parameterization schemes are analyzed in the cloud-resolving model simulations of four rainfall cases over the tropics and midlatitudes. The comparison of time and model domain mean data shows that Shen's scheme produces the closest rainfall simulation to the observation. Compared to Zeng's scheme,Shen's scheme improves the mean rain-rate simulation significantly through the dramatic decrease in depositional growth of cloud ice from cloud water. Compared to other schemes, Shen's scheme produces the better rainfall simulation via the reduction in the mean rain rate associated with the enhanced gain of cloud water and ice.
文摘The diffraction angular distributions are calculated for different ice crystals (e.g,solid and hollow hexagonal columns,solid plates and single hexagonal bullet) randomly oriented in space,based on the theory of Cai and Liou.Results of solid column and plate are compared with those from formulas of Wendling et al and Liou.The resull comparison shows that all three procedures discussed in this paper have good agreement.After considering the coin putation time and comparison results,it is suggested that the formula of Wendling et al.can be used to calculate the solid column diffraction,and the formula of Liou can be used to calculate the plate diffraction.The comparison also shows that the diffraction results of solid columu,hollow column and single bullet ice particles randomly oriented in space are very close.
基金financial support of this study from the National Key Technologies R&D Program of China during the 12th Five-Year Plan period (2012BAD38B09)the National Natural Science Foundation of China (NSFC31301417)
文摘aquatic product, known as one of the good resources for white meat, has been widely accepted by the consumers due to its high protein, low fat, especially low cholesterol. With the fast development of living standards around the world, the consumer demands for high quality, nutrition, safety and freshness of ifshery food are increasing. Thus, high efifcient preservation technologies for aquatic products become particularly important. Superchilling is one of the controlled-temperature preservation technologies for seafood. Aquatic products can be kept in better quality under superchilling conditions. This review introduced the principle and development of superchilling process, mainly focusing on research progresses and technical dififculties of superchilling. The growth mechanism of ice crystals and the feasibility of application of computational lfuid dynamics in analyzing the temperatures variation and ice crystals during superchilling progress were also discussed, which will provide theoretical foundation for its improvement and application.
基金supported by the National Key Research and Development Program of China(2022YFC2100800)the National Natural Science Foundation of China(22078238,52373117,and U23B20121)+1 种基金the Haihe Laboratory of Sustainable Chemical Transformations(24HHWCSS00005)the Open Funding Project of the National Key Laboratory of Biochemical Engineering.
文摘Cryopreservation is a promising technique for the long-term storage of skin.However,the formation of ice crystals during cryopreservation unavoidably damages skin structure and functionality.Currently,the lack of thorough and systematic investigation into the internal mechanisms of skin cryoinjury obstructs the advancement of cryopreservation technology.In this study,we identified 3 primary contributors to skin cryoinjury:interfacial ice nucleation,stress accumulation,and thermal stress escalation.We emphasized the paramount role of interfacial ice nucleation in provoking ice growth within the skin during the cooling process.This progress subsequently leads to stress accumulation within the skin.During the rewarming process,the brittleness of skin,previously subjected to freezing,experienced a marked increase in thermal stress due to ice recrystallization.Based on these insights,we developed a novel zwitterionic betaine-based solution formulation designed for cryopreservation skin.This cryoprotective agent formulation exhibited superior capability in lowering ice nucleation temperatures and inhibiting ice formation at interfaces,while also facilitating the growth of smooth and rounded ice crystals compared to sharp-edged and cornered crystals formed in aqueous solutions.As a result,we successfully achieved prolonged cryopreservation of the skin for at least 6 months,while preserving 98.7%of structural integrity and 94.7%of Young’s modulus.This work provides valuable insights into the mechanisms of ice crystal damage during organ cryopreservation and profoundly impacts the field of organ transplantation and regenerative medicine.
基金the financial support through Research University Grant and Fundamental Research Grant Scheme(Vot nos.04H46 and 4F224)Chemical Engineering Department,Universiti Teknologi PETRONAS for its support
文摘This study presents a novel design for a spiral finned crystallizer which is the primary element of progressive freeze concentration(PFC) system, which simplifies the setup of the conventional system. After the crystallizer has been designed, the research experiments have been conducted and evaluated through a thorough analysis of its performance by developing a mathematical model that can be used to predict the productivity of ice crystal at a range of coolant temperature. The model is developed based on the basic heat transfer equation, and by considering the solution's and the coolant's convective heat transfer coefficient(h) under the forced flow condition.The model's accuracy is verified by making comparison between the ice crystal mass' experimental value and the values predicted by the model. Consequently, the study found that the model helps in enhancing the PFC system.
基金supported by the National Natural Science Foundation of china(51906178)Postdoctoral research Foundation of china(2022t150503).
文摘The low temperature is an effective method for postharvest fruits preservation.However,the ice crystal nucleation caused by low temperature significantly decreases the quality of fruits.in this paper,the effects of alternating magnetic field(aMF)on the ice nucleation temperature of grape were investigated,and the aMF continued treatment and aMF intermittent treatment(20 Gs,60 Hz)assisted near-freezing temperature(aMct/aMit-NFt)were used to store grapes at(−2.5±0.2)℃.compared with the untreated group,aMF decreased the ice nucleation temperature of grape 1℃.Meanwhile,results demonstrated that aMct/aMit-NFt storage improved sensory properties and antioxidant capacity of grapes,with the overall effect of aMit treatment being the most favorable.after 9 days of storage,the color difference and polyphenol oxidase(PPo)activity of aMit treatment were reduced by 17%and 12%,respectively,compared with the untreated group,and it effectively slowed down malonaldehyde(MDa)accumulation.these conclusions show that aMct/aMit-NFt storage is an effective tool for prolonging the shelf life of grapes.
基金This project was supported by National Natural Science Foundation of China.
文摘The ice forming rates p_i produced by supersonic flow have been measured in supercooled fog suspended in a cold chamber at temperatures of 0 to-12℃.It has been shown that the ice-forming rates are 10^(11)to 10^(12)crystals per gram of air at Mach numbers of 1.1 to 1.84 and total pressures below 6 atm,and that the ice-forming rates slowly increase with increasing Mach numbers and total pressures and with decreasing ambient temperatures.These results are theoretically consistent with the rules for expansion in supersonic flow. In review of mechanisms of ice crystal generation,authors propose that the homogeneous nucleation-freezing (condensation-freezing)of water vapor in supersonic flow be the dominant mechanism.In our opinion,supersonic flow, for artificial precipitation,could be expected to provide an economical,non-polluting and convenient technology,and suitable for the long-distance operation.The data obtained from our experiments indicate that it is feasible to develop a new technique for weather modification.
