Ice Mass Fraction Research Articles

Investigating the performance of ice slurry system and the growth of ice crystals using seawater

This study investigates ice slurry systems, their transport characteristics, and seawater ice crystal formation through microscopy. Here, the salinity of seawater was set to vary between 10 and 30 ppt (part per thousand) and was used to form ice slurries. Pump flow rates were adjusted to be in between 5 and 30 L/min, while the scraper speed was set to vary at 350-550 RPM in positive correlation with the speed. It was discovered that ice slurries generated with a salinity of 10 ppt seawater had a significantly positive effect on ice production rate. Additionally, such ice slurries resulted in an intended reduction on the formation time of the ice slurries, while the flow and stirring rates were maintained between 10 to 15 L/min and 400 to 450 RPM, respectively. Additionally, the transport characteristics of the ice slurry were affected in terms of the increase in flow rate, salinity, and ice mass fraction. As an interesting threshold, the diameter of the ice crystals increased as storage time increased, and seawater concentration decreased, which was followed by agglomeration and the Ostwald ripening phenomenon. For cold storage applications, therefore, a low salinity of seawater (10-20 ppt) and 60 % ice mass fraction were recommended to deliver the best intended performance in an ice slurry system.

Time evolution of dust deposits in the Hapi region of comet 67P/Churyumov-Gerasimenko

Aims. We provide a measurement of the seasonal evolution of the dust deposit erosion and accretion in the Hapi region of comet 67P/Churyumov-Gerasimenko with a vertical accuracy of 0.2–0.9 m. Methods. We used OSIRIS Narrow Angle Camera images with a spatial scale of lower than 1.30 m px−1 and developed a tool to monitor the time evolution of 22 boulder heights with respect to the surrounding dust deposit. The tool is based on the measurement of the shadow length projected by the boulder on the surrounding pebble deposit. Assuming the position of the boulders does not change during the observational period, boulder height variations provide an indication of how the thickness of the surrounding dust layer varies over time through erosion and accretion phenomena. Results. We measured an erosion of the dust deposit of 1.7 ± 0.2 m during the inbound orbit until 12 December, 2014. This value nearly balances the fallout from the southern hemisphere during perihelion cometary activity. During the perihelion phase, the dust deposit then increased by 1.4 ± 0.8 m. This is interpreted as a direct measurement of the fallout thickness. By comparing the erosion rate and dust volume loss rate at the Hapi region measured in the coma, the fallout represents ~96% in volume of the ejecta. The amount of the eroded pristine material from the southern hemisphere, together with its subsequent transport and fallout on the nucleus, led us to discuss the pristine water ice abundance in comet 67P. We determine that the refractory-to-ice mass ratio ranges from 6 to 110 in the perihelion-eroded pristine nucleus, providing a pristine ice mass fraction of (8 ± 7)% in mass.

Analysis of Entropy Generation Rate During Non-Adiabatic Ice Slurry Flow in Pipes

The paper focuses on the entropy generation rate minimization during the flow of ethanol-based ice slurry through straight pipes with a circular and rectangular cross-section. The authors’ original equations for calculating ice slurry flow resistances and heat transfer coefficients were used to determine the impact of the mass fraction of ice, ice slurry flow velocity and heat flux density on the entropy generation rate values observed during flow through pipes. A dimensionless relationship was proposed to determine the interdependency between flow velocity and mass share of ice for which the entropy values were at the minimum level.

Effect of ice mass fraction on ice slurry flow for cold energy storage application

The characteristics of ice slurry flows in a pipe are critical due to the potential consequence of pressure drops. This work attempted to conduct an experimental study on ice slurry flow in a horizontally posited circular pipe. This study was conducted on glycol-added (20%) ice slurry with varied ice mass fractions (10%, 15% 20%, 25%, 30%). During experiments, the flow tests were conducted by covering both laminar and turbulent flows. Results of the investigation discovered ice slurry to behave as a Newtonian fluid at mass fraction below 10%, while it also behaved as a non-Newtonian fluid at mass fraction up to 15%. Then, pressure drop was revealed to increase significantly at low-speed settings and high ice mass fractions. To maximize the use of ice slurry as a cold energy storage, therefore, ice mass fraction must be kept at below 20% in a laminar flow.

Rheology of Ice Slurry in Circular Pipe at Different Freezing-Point Depressants

The utilization of ice slurry as a pumpable phase-change material has been getting a lot of attention in research and development discourses. This study attempted to investigate the rheological characteristics of ice slurry at different freezing-point depressants through experiments. Ice slurry was formed by mixing water and different freezing-point depressants (monoethylene glycol, ethanol, and sodium chloride) at a 20% initial concentration. Rheology tests were conducted on the transition from laminar to turbulent flows in a circular pipe. The inner dimension of the pipe was 12.7[Formula: see text]mm in diameter, while the ice mass fraction varied in between 0–28% depending on storage time of ice slurry. Experimental results showed sodium chloride ice slurry to have a higher pressure drop and friction factor compared to those of monoethylene glycol and ethanol ice slurry ones at the same initial concentration and ice mass fraction level. In general, ice slurry was discovered to behave as a Newtonian fluid at 10–15% ice mass fractions, as a shear thinning fluid at 15–20% ice mass fractions, and a shear thickening fluid at 20–28% ice mass fractions. Later, experimental data of shear stress were compared to Ostwald–deWaele and Herschel–Bulkley models based on Mellari method. In fact, a modified Herschel–Bulkley model for monoethylene glycol ice slurry showed a close agreement with experimental data with 4.7% mean deviation. In addition, the experimental viscosity data were compared to the Einstein, Jeffrey, Kunitz, Guth, Steimour, Vand, Mooney, Simha, Happel, Ford, Thomas dan Morio–Ototake models. The best fit was only produced with Morio model for values at low ice mass fraction ([Formula: see text]%).

Thermo-Fluidic Characteristics of Two-Phase Ice Slurry Flows Based on Comparative Numerical Methods

Ice slurry is a potential secondary refrigerant for commercial refrigeration systems because of its remarkable thermal properties. It is necessary to optimize the heat transfer process of ice slurry to reduce the energy consumption of the refrigeration system. Thus, this study investigates the heat transfer performance of single-phase (aqueous solution) and two-phase (ice slurry) refrigerants in a straight horizontal tube. The numerical simulations for ice slurry were performed with ice mass fraction ranging from 5% to 20%. The effects of flow velocity and ice concentration on the heat transfer coefficient were examined. The results showed that heat transfer coefficient of ice slurry is considerably higher than those of single-phase flow, particularly at high flow velocity and ice content, where increase in heat transfer with a factor of two was observed. The present results confirmed that ice slurry heat transfer ability is considerably affected by flow velocity and ice concentration in laminar range. Moreover, the second part of this paper reports on the credibility three distinct two-phase Eulerian–Eulerian models (volume of fluid (VOF), mixture, and Eulerian) for the experimental conditions reported in the literature. All two-phase models accurately predict the thermal field at low ice mass fraction but underestimate that at high ice mass fractions. Regardless of the thermal discrepancies, the Eulerian–Eulerian models provide quite reasonable estimation of pressure drop with reference to experimental data. The numerical predictions from the VOF model are more accordant with the experimental results and the maximum percentage error is limited to ~20% and ~13% for thermal and pressure drop predictions, respectively.

The Galilean Satellites Formed Slowly from Pebbles

Abstract It is generally accepted that the four major (Galilean) satellites formed out of the gas disk that accompanied Jupiter’s formation. However, understanding the specifics of the formation process is challenging, as both small particles (pebbles) and the satellites are subject to fast migration processes. Here we hypothesize a new scenario for the origin of the Galilean system, based on the capture of several planetesimal seeds and subsequent slow accretion of pebbles. To halt migration, we invoke an inner disk truncation radius, and other parameters are tuned for the model to match physical, dynamical, compositional, and structural constraints. In our scenario it is natural that Ganymede’s mass is determined by pebble isolation. Our slow pebble accretion scenario then reproduces the following characteristics: (1) the mass of all the Galilean satellites; (2) the orbits of Io, Europa, and Ganymede captured in mutual 2:1 mean motion resonances; (3) the ice mass fractions of all the Galilean satellites; and (4) the unique ice-rock partially differentiated Callisto and the complete differentiation of the other satellites. Our scenario is unique to simultaneously reproduce these disparate properties.

The REASONS Survey: Resolved Millimeter Observations of a Large Debris Disk around the Nearby F Star HD 170773

Abstract Debris disks are extrasolar analogs to our own Kuiper Belt and they are detected around at least 17% of nearby Sun-like stars. The morphology and dynamics of a disk encode information about its history, as well as that of any exoplanets within the system. We used the Atacama Large Millimeter/submillimeter Array (ALMA) to obtain 1.3 mm observations of the debris disk around the nearby F5V star HD 170773. We image the face-on ring and determine its fundamental parameters by forward-modeling the interferometric visibilities through a Markov Chain Monte Carlo approach. Using a symmetric Gaussian surface density profile, we find a 71 ± 4 au wide belt with a radius of au, a relatively large radius compared with most other millimeter-resolved belts around late A/early F type stars. This makes HD 170773 part of a group of four disks around A and F stars with radii larger than expected from the recently reported planetesimal belt radius—stellar luminosity relation. Two of these systems are known to host directly imaged giant planets, which may point to a connection between large belts and the presence of long-period giant planets. We also set upper limits on the presence of CO and CN gas in the system, which imply that the exocomets that constitute this belt have CO and HCN ice mass fractions of <77% and <3%, respectively. This is consistent with solar system comets and other exocometary belts.

Effect of the Mass Fraction of Ice on the Strain Rate Dependence of Strength under Dynamic Fracture of Frozen Soil

Experimental dependences of the strength of frozen sandy soil on strain rate are analyzed using a structural–temporal approach. Results of dynamic uniaxial compression tests at a temperature of −18°C and strain rates of 400 to 2600 s−1 of frozen sandy soil specimens of two types with an ice mass fraction of 10 and 18% measured at room temperature are presented. The strain rate dependence at different freezing temperatures of frozen sand with an ice mass fraction of 30% is studied using known experimental data.

Ice slurry flow through gate valves – local pressure loss coefficient

The paper presents the calculation results of local pressure loss coefficient in three different models of a gate valve in their two opening positions. The study was carried out on ice slurry with the mass fraction of ice particles of 30%, 25%, 20%, 15%, 10% and 5%. The slurry is considered to be the Bingham Plastic liquid within this study and the local loss coefficient data were provided thanks to the obtained results of the local resistance calculations in the fittings tested in the experimental investigation. The transitional behavior of ice slurry has been detected. The value of the local pressure loss coefficient decreases firstly up until transition point then it remains constant in the turbulent flow regime. The ice crystals content directly determines its value, as the larger ice mass fraction in the mixture, the greater value of the loss coefficient. Declining opening position of the gate valves results in decreasing the value of the loss coefficient data in relation to the Reynolds number for Bingham liquid.

A laboratory-based dielectric model for the radar sounding of the martian subsurface

For the last decade, the SHARAD radar on board NASA’s Mars Reconnaissance Orbiter, and the MARSIS radar on board ESA’s Mars Express, have sounded the surface and subsurface of Mars from orbit to search for and characterise water ice reservoirs. When associated with dielectric models, the regolith composition (in terms of dust, ice and voids) of the surface and subsurface can be extracted from these data. These models describe the electromagnetic properties of the material as a function of its chemical and physical properties. With the goal of improving the currently available dielectric models for Martian icy regolith, we conducted laboratory measurements of the dielectric properties of the JSC Mars-1 Martian soil simulant mixed with water ice, varying the water ice mass fraction from 0 to 76%. Our measurements were performed between 50 MHz and 2 GHz, at ambient temperature, and at 243 K. The samples had porosities between 40% and 72%. Based on these, we propose a model that relates the dielectric constant of the sounded material to its volume fraction of water ice and/or of JSC Mars-1, its porosity, and its temperature. Tuned to the relevant frequencies, our dielectric model can be used to estimate the volume fraction of water ice from the radar sounding data of SHARAD and MARSIS. It is similarly relevant for the interpretation of data from the WISDOM radar, which will be part of the science payload of the ExoMars 2020 rover.

Thermo-Hydrodynamics of a Helical Coil Heat Exchanger Operated with a Phase-Change Ice Slurry as a Refrigerant

ABSTRACTThe thermal performance of helical-coil heat exchangers can be significantly enhanced when operated with ice slurry as a phase-change refrigerant. It is essential to also consider the hydrodynamics of ice slurry flow to determine the overall performance of the heat exchanger. This study presents a detailed numerical investigation of the thermo-hydrodynamic performance of a helical coil heat exchanger operated with a laminar and non-Newtonian flow of ethyl-alcohol ice slurry subject to phase change. The Bingham plastic model is used to reflect the non-Newtonian behavior of ice slurry. The phase change of ice slurry is modelled using the enthalpy-porosity method. The pressure drop and heat transfer of ice slurry in a double-turn helical coil are determined in terms of ice mass fraction and Dean number. The results show that an increase in the ice mass fraction and Dean number results in an increase of the heat transfer rate. This is, however, associated with an increase in pressure drop. The entropy generation analysis is introduced to evaluate the overall performance of the heat exchanger, taking into account the opposing effects of heat transfer and pressure drop. It is evident that, at certain ice mass fractions, there exists an optimal value of the Dean number that leads to minimum irreversibility and maximum overall performance.

Driven by excess? Climatic implications of new global mapping of near-surface water-equivalent hydrogen on Mars

We present improved Mars Odyssey Neutron Spectrometer (MONS) maps of near-surface Water-Equivalent Hydrogen (WEH) on Mars that have intriguing implications for the global distribution of “excess” ice, which occurs when the mass fraction of water ice exceeds the threshold amount needed to saturate the pore volume in normal soils. We have refined the crossover technique of Feldman et al. (2011) by using spatial deconvolution and Gaussian weighting to create the first globally self-consistent map of WEH. At low latitudes, our new maps indicate that WEH exceeds 15% in several near-equatorial regions, such as Arabia Terra, which has important implications for the types of hydrated minerals present at low latitudes. At high latitudes, we demonstrate that the disparate MONS and Phoenix Robotic Arm (RA) observations of near surface WEH can be reconciled by a three-layer model incorporating dry soil over fully saturated pore ice over pure excess ice: such a three-layer model can also potentially explain the strong anticorrelation of subsurface ice content and ice table depth observed at high latitudes. At moderate latitudes, we show that the distribution of recently formed impact craters is also consistent with our latest MONS results, as both the shallowest ice-exposing crater and deepest non-ice-exposing crater at each impact site are in good agreement with our predictions of near-surface WEH. Overall, we find that our new mapping is consistent with the widespread presence at mid-to-high Martian latitudes of recently deposited shallow excess ice reservoirs that are not yet in equilibrium with the atmosphere.

Thermal evolution of trans‐Neptunian objects, icy satellites, and minor icy planets in the early solar system

AbstractNumerical simulations are performed to understand the early thermal evolution and planetary scale differentiation of icy bodies with the radii in the range of 100–2500 km. These icy bodies include trans‐Neptunian objects, minor icy planets (e.g., Ceres, Pluto); the icy satellites of Jupiter, Saturn, Uranus, and Neptune; and probably the icy‐rocky cores of these planets. The decay energy of the radionuclides, 26Al, 60Fe, 40K, 235U, 238U, and 232Th, along with the impact‐induced heating during the accretion of icy bodies were taken into account to thermally evolve these planetary bodies. The simulations were performed for a wide range of initial ice and rock (dust) mass fractions of the icy bodies. Three distinct accretion scenarios were used. The sinking of the rock mass fraction in primitive water oceans produced by the substantial melting of ice could lead to planetary scale differentiation with the formation of a rocky core that is surrounded by a water ocean and an icy crust within the initial tens of millions of years of the solar system in case the planetary bodies accreted prior to the substantial decay of 26Al. However, over the course of billions of years, the heat produced due to 40K, 235U, 238U, and 232Th could have raised the temperature of the interiors of the icy bodies to the melting point of iron and silicates, thereby leading to the formation of an iron core. Our simulations indicate the presence of an iron core even at the center of icy bodies with radii ≥500 km for different ice mass fractions.

Effects of the Wegener–Bergeron–Findeisen process on global black carbon distribution

Abstract. We systematically investigate the effects of Wegener–Bergeron–Findeisen process (hereafter WBF) on black carbon (BC) scavenging efficiency, surface BCair, deposition flux, concentration in snow (BCsnow, ng g−1), and washout ratio using a global 3-D chemical transport model (GEOS-Chem). We differentiate riming- versus WBF-dominated in-cloud scavenging based on liquid water content (LWC) and temperature. Specifically, we implement an implied WBF parameterization using either temperature or ice mass fraction (IMF) in mixed-phase clouds based on field measurements. We find that at Jungfraujoch, Switzerland, and Abisko, Sweden, where WBF dominates in-cloud scavenging, including the WBF effect strongly reduces the discrepancies of simulated BC scavenging efficiency and washout ratio against observations (from a factor of 3 to 10 % and from a factor of 4–5 to a factor of 2). However, at Zeppelin, Norway, where riming dominates, simulation of BC scavenging efficiency, BCair, and washout ratio become worse (relative to observations) when WBF is included. There is thus an urgent need for extensive observations to distinguish and characterize riming- versus WBF-dominated aerosol scavenging in mixed-phase clouds and the associated BC scavenging efficiency. Our model results show that including the WBF effect lowers global BC scavenging efficiency, with a higher reduction at higher latitudes (8 % in the tropics and up to 76 % in the Arctic). The resulting annual mean BCair increases by up to 156 % at high altitudes and at northern high latitudes because of lower temperature and higher IMF. Overall, WBF halves the model–observation discrepancy (from −65 to −30 %) of BCair across North America, Europe, China and the Arctic. Globally WBF increases BC burden from 0.22 to 0.29–0.35 mg m−2 yr−1, which partially explains the gap between observed and previous model-simulated BC burdens over land. In addition, WBF significantly increases BC lifetime from 5.7 to ∼ 8 days. Additionally, WBF results in a significant redistribution of BC deposition in source and remote regions. Specifically, it lowers BC wet deposition (by 37–63 % at northern mid-latitudes and by 21–29 % in the Arctic), while it increases dry deposition (by 3–16 % at mid-latitudes and by 81–159 % in the Arctic). The resulting total BC deposition is lower at mid-latitudes (by 12–34 %) but higher in the Arctic (by 2–29 %). We find that WBF decreases BCsnow at mid-latitudes (by ∼ 15 %) but increases it in the Arctic (by 26 %) while improving model comparisons with observations. In addition, WBF dramatically reduces the model–observation discrepancy of washout ratios in winter (from a factor of 16 to 4). The remaining discrepancies in BCair, BCsnow and BC washout ratios suggest that in-cloud removal in mixed-phased clouds is likely still excessive over land.

Numerical and analytical investigations of heat transfer for a finned tube heat exchanger with ice slurry as cooling medium

Using ice slurry as cooling medium in HVAC systems has potential due to its high energy capacity. In order to investigate heat transfer characteristics in finned tube cross-flow heat exchangers with ice slurry as a cooling medium, a numerical method with volume of fluid model and an analytical method are applied. The composition of ice slurry considered for analysis is a carrier fluid (9 wt% sodium chloride solution) and ice crystals with mass fraction at 5%–35%. Results from the proposed methods are primarily validated via comparing with the experimental data from the published literature. Both the numerical and analytical results reveal that the ice crystals have a positive effect on heat transfer of the heat exchanger. Heat transfer rate of the heat exchanger increases with the inlet ice mass fraction rising, and then it will reach a relative stable value. It is also found that the heat transfer rate almost increases linearly with the air inlet temperature. In addition, the numerical results of the airflow temperature field reveal that extending the width of the fins at the downstream direction of the airflow is favorable to the heat exchanging performance of the ice slurry finned tube heat exchanger. Finally, it is beneficial for the analytical method to obtain reliable results when the ice mass fraction difference between the ice slurry inlet and outlet remains no more than 8%.

Controlled boiling on Enceladus. 1. Model of the vapor-driven jets

Plumes of water vapor and ice particles have been observed from the so-called tiger stripes at the south polar terrain (SPT) of Saturn’s satellite, Enceladus. The observed high salinity (∼0.5–2%) of the ice particles in the plumes may indicate that the plumes originate from a subsurface liquid ocean. Additionally, the SPT is the source of strong infrared radiation (∼4.2 GW), which is especially intense near (within tens of meters) the tiger stripes. This could indicate that the radiation is associated with plume activity, but the connection remains unclear. Here we investigate the constraints that plume observations place on the widths of the cracks, the depth to the liquid-vapor interface, and the mechanisms controlling plume variability. We solve the fluid dynamics of the flow in the crack and the interaction between the flow and ice walls assuming that the flows of water vapor and ice particles originate from a few kilometers deep liquid ocean. For a crack with a uniform width, we find that our model could explain the observed vapor mass flow rate of the plumes when the crack width is 0.05–0.075 m. A wider crack is not favorable because it would produce a higher vapor mass flow rate than the observed value, but it may be allowed if there are some flows that do not reach the surface of Enceladus either due to condensation on the icy walls or the tortuosity of the crack. The observed heat flow can be explained if the total crack length is approximately 1.7 × 500 km. A tapering crack (a crack which is ∼1 m wide at the bottom of the flow and sharply becomes 0.05–0.075 m at shallower depths) can also explain the observed vapor mass flow rate and heat flow. Widths of 1 m or more are necessary to avoid freezing at the liquid-vapor interface, as shown in our paired paper (Ingersoll and Nakajima [2016] Icarus). The observed intense heat flow along the tiger stripes can be explained by the latent heat release due to vapor condensation onto the ice walls near the surface. The resulting buildup of ice causes the vents to seal themselves on time scales less than a year. We also find that the ice to vapor ratio of the plumes is sensitive to the ice mass fraction at the bottom of the flow (liquid–vapor interface). We find that the total mass flow rate of the plumes becomes larger when the crack width is larger, which is consistent with the observation that the flow rate increases near the orbital apocenter, where the crack is expected to be widest.

Experimental investigations of ice slurry flows in horizontal pipe based on monopropylene glycol

In this paper, the pressure drop behavior of ice slurry based on MPG-water in a circular horizontal tube is experimentally investigated. The secondary fluid was prepared by mixing MPG and water to obtain initial MPG concentration varying from 5% to 24%. The pressure drop tests were conducted to cover laminar flow with ice mass fraction varying from 5% to 25% depending on test conditions. Results from test reveal that the ice slurry behaves as non-Newtonian: thickening flow (n > 1) or shear thinning flow (n < 1) and sometimes as Newtonian flow (n ≈ 1). The moving bed is observed in particular flow conditions.The experimental results for viscosities were compared to the analytical results. In addition, experimental results of the Darcy friction factor were compared to Poiseuille model who gives good agreement with experimental results.Furthermore, for transport purposes, it has been shown that 11% initial MPG concentration gives the best results.

CFD Study of Ice Slurry Heat Transfer Characteristics in a Straight Horizontal Tube

Ice slurry heat transfer characteristics in a straight horizontal tube were numerically studied in this paper. By using of CFD software, the VOF model in FLUENT 6.3, the simulation of ice slurry was performed to cover laminar and turbulent flow regimes with Cis varying from 0% to 20%. The obtained results were firstly validated by the published experimental values. It is found that the discrepancy between the measured and calculated Nuis number is mainly in the range of ±15%. Then the model was applied to analyze the impact of initial conditions on ice slurry heat transfer. The present work shows that, ice slurry heat transfer performance are strongly dependent on the flow velocity and ice mass fraction, and heat flux density only has a small influence on the value of Nuis when ice slurry flows in turbulence. This paper aimed to use this model as a design tool to analyze ice slurry flow in different operating conditions.

Mathematical Model of Heat Transfer for a Finned Tube Cross-flow Heat Exchanger with Ice Slurry as Cooling Medium

Using ice slurry as a secondary refrigerant in HVAC systems has many potential benefits for its high cooling capacity. In order to investigate heat transfer characteristics such as heat transfer rate and heat transfer coefficient in finned tube cross-flow heat exchangers with ice slurry as cooling medium, a mathematical model describing heat transfer process of the heat exchanger has been developed, which are based on three sets of partial differential equations (PDEs) of energy balance. Then an analytical solution has been obtained through solving the PDEs model. The analytical solution of the proposed model presents a reasonable agreement with the experimental data from the published literature when ice mass fraction is between 5% and 25%. In addition, the relationship between the heat transfer rate and the melting amount of ice crystals is also obtained.