Effect of Prewetting Brines and Mixing on Ice-Melting Rate of Salt at Cold Temperatures: New Tracer Dilution Method

2017 ◽  
Vol 2613 (1) ◽  
pp. 71-78 ◽  
Author(s):  
Scott Koefod
Keyword(s):  
Freezing Point ◽  
Melting Rate ◽  
Test Method ◽  
Dilution Method ◽  
Ice Melting ◽  
Cold Temperatures ◽  
Ice Melt ◽  
Solid Salt ◽  
Different Temperatures ◽  
Tracer Dilution

A novel test method has been developed to measure the ice-melting rate of deicers. The ice-melting rates of prewetted salt were determined by measuring the change in the concentration of chloride (Cl−) or magnesium or calcium cations (Mg2+ or Ca2+, respectively) in the ice melt as tracers. The method is substantially more precise than the SHRP H205.1 standard and has the further advantage of measuring ice-melting and salt dissolution rates simultaneously. Brines were preequilibrated with ice at −19.3°C (−2.7°F) and blended with solid salt to determine the effect of different prewetting brines on the ice-melting rate of the solid salt component only. The measured equilibrium ice-melting capacity of sodium chloride (NaCl) agreed well with the theoretical value calculated from the NaCl freezing point curve. Under a condition of no mixing, solid salt yielded 0.87% of its total available ice-melting capacity after 60 min when wetted with NaCl brine and 9.7% when wetted with calcium chloride (CaCl2) brine. Mixing raised the yield of ice melt to 27.1% and 50.5% after 60 min when wet with NaCl and CaCl2 brines, respectively. The CaCl2 brine was slightly more effective than the magnesium chloride (MgCl2) brine at enhancing the ice-melting rate of salt. The test method promises to be a useful tool for permitting a more precise optimization of prewetting brine composition, concentration, and brine-to-salt ratio at different temperatures. The method may also permit better determination of the cost-effectiveness of different prewetting strategies and provide deeper insights into the mechanism of chemical ice melting.

Mechanical and tribological properties of ice-bonded abrasive polishing tools

2017 ◽  
Vol 233 (1) ◽  
pp. 132-144 ◽  
Author(s):  
S Rambabu ◽  
N Ramesh Babu
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Melting Rate ◽  
Wear Behaviour ◽  
Mechanical And Tribological Properties ◽  
Different Temperatures ◽  
Long Time ◽  
Polishing Tool ◽  
Hardness Coefficient

This article covers the efforts on characterising ice-bonded abrasive polishing tool in terms of the mechanical and tribological properties such as hardness, coefficient of friction, and wear rate. These studies were attempted on the tools prepared at different temperatures ranging from −10 °C to 0 °C with a view to identify the condition suitable to prepare ice-bonded abrasive polishing tool for effective polishing of Ti–6Al–4V alloy specimen. It also presents the methods adopted to determine various properties of ice-bonded abrasive polishing tool. Hardness was estimated from the measured penetration depth of cone shape indenter into the tool, coefficient of friction was determined from the change in power drawn by the motor rotating the tool mould, and wear behaviour of tool was assessed from the melting rate of the tool determined from the change in height of ice-bonded abrasive polishing tool at different stages of polishing. From the results of this study, it is clear that ice-bonded abrasive polishing tool prepared at −4 °C has possessed sufficient hardness, coefficient of friction, and reasonable wear rate suitable for polishing of Ti–6Al–4V specimens. This article also covers the details of low-temperature coolant supply unit developed to prepare the ice-bonded abrasive polishing tool at any desired temperature between 0 °C and −40 °C and thus to maintain it for a long time. Polishing studies with such ice-bonded abrasive polishing tool showed 72% improvement in finish after 90 min of polishing of Ti–6Al–4V specimen with tool, prepared at −4 °C.

Fasteners at Low Temperatures: Characterization and Methods for Design

2011 ◽  
Author(s):  
Melanie Stephan ◽  
Jens O. Weber ◽  
Ulrich Wuttke ◽  
Christina Berger
Keyword(s):  
Impact Test ◽  
Freezing Point ◽  
Lattice Structure ◽  
Detailed Examination ◽  
Test Methods ◽  
Climatic Conditions ◽  
Test Method ◽  
Design Concepts ◽  
Ductile Behavior ◽  
Pendulum Impact

Bolted joints are a major part of wind energy plants. Due to climatic conditions, they are often exposed to temperatures far below the freezing point. Together with the multiaxial state of stress, which results from the notch effect of the thread, and possible dynamic overloads during operation, sufficient ductility of the material is needed. The state of the art method to investigate the ductile behavior of fasteners is the Charpy pendulum impact test with a V-notched specimen. According to international standard DIN EN ISO 898-1 [1] respectively ASTM F568M-07 [2], fasteners made of carbon steel and alloy steel with a body centered cubic lattice structure can be used for temperatures down to 223 K (−50°C, −58°F) as long as a minimum impact energy of 27 J at 253 K (−20°C, −4°F) is met. As there are several disadvantages in using this test method for fasteners, a detailed examination of existing test methods and design concepts is necessary to find alternatives to the Charpy pendulum impact test. Extensive quasi-static and dynamic material tests were conducted on fasteners with property classes 5.6, 10.9 and 12.9 in a temperature range between 203 K (−70°C, −94°F) and room temperature 293 K (20°C, 68°F). Both mechanical properties and the influence of different specimen geometries were evaluated. Analytical concepts for the description of the low temperature applicability of different steels were analyzed.

scholarly journals Investigations on the Effects of Seasonal Temperature Changes on the Electrical Resistance of Living Trees

Forests ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 550 ◽  
Author(s):  
Xiaoquan Yue ◽  
Lihai Wang ◽  
Xiaolong Shi ◽  
Mingxian Xu ◽  
Zhiming Zhu
Keyword(s):  
Moisture Content ◽  
Regression Model ◽  
Cross Sections ◽  
Electrical Resistance ◽  
Freezing Point ◽  
Seasonal Temperature ◽  
Populus Simonii ◽  
Standing Trees ◽  
Different Temperatures ◽  
The Cross

In order to use the electrical resistance method to accurately and timely detect and evaluate the internal decay defects of living trees, the effects of the seasonal temperature and moisture content on the electrical resistance of standing trees were investigated. At the Northeast Forestry University Experimental Forest Farm, Harbin, Heilongjiang Province of China, Populus simonii Populus simonii Carr. and Larix gmelinii (Rupr.) Rupr. were selected as the objects and the electrical resistance of standing trees was tested through different seasons from December 2016 to December 2017. Meanwhile, the effects of changes in the seasonal temperatures (−20 to −10 °C, −10 to −5 °C, −5 to 0 °C, 0 to 5 °C, 5 to 10 °C, 10 to 15 °C, 15 to 25 °C) as well as changes in the moisture content (MC) (Populus simonii, MC ≥ 103%; Larix gmelinii, MC ≥ 77.5%) on the electrical resistance in the cross-sections of living trees were studied. The influence of temperature at different moisture contents, the moisture content at different temperatures, and their combined effects on electrical resistance were analyzed, following which a regression model was also established. The obtained results indicated that ambient temperature had a significant effect on the average value of electrical resistance in the cross-section of living trees when temperatures were below the freezing point. There was a sudden discontinuity near the freezing point, and logR (logarithm value of electrical resistance) in the cross-sections of sound trees and decayed trees changed in a similar trend with variations in the temperature. While the effect of moisture content on logR in the cross-sections of threes was insignificant at different temperatures because of the moisture content above FSP (fiber saturation point). It indicated that the temperature and moisture content had interactive effects on logR in the cross-sections. The binary linear regression model between moisture content, temperature, and logR was highly fitted with a correlation coefficient (R2) higher than 0.8. The outcome of this investigation indicates that when non-destructive testing is performed on living trees using electrical resistance at different seasonal temperatures, the measured results need to consider both the temperature and moisture content. For practical work, it is not recommended to consider testing living trees near the freezing point temperature using the electrical resistive tomography. Below the freezing point, the electrical resistance changes with temperature greatly relative to the normal temperature. Therefore, when performing the detection of electrical resistance, it is necessary to calibrate the effects of temperature

Mechanical Behavior of Iron Boride Formed in the Surface of an AISI W2

2015 ◽  
Vol 365 ◽  
pp. 142-147 ◽  
Author(s):  
T. de la Mora-Ramírez ◽  
D. Sánchez Huerta ◽  
N. López-Perrusquia ◽  
M.A. Doñu Ruiz ◽  
E.A. Cerrillo-Moreno ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Steel Substrate ◽  
Boride Layer ◽  
Test Method ◽  
X Ray Diffraction ◽  
Iron Boride ◽  
Different Temperatures ◽  
Steel Aisi ◽  
Constant Distance ◽  
Boriding Process

The present study reports the growth of layers formed in the surface of the boride steel AISI W2; by the application of the dehydrated paste-pack boriding process and using three different temperatures at 1173, 1223 and 1273 K, with 2, 4, 6 and 8 h of exposure. The substrate and the boride Fe2B were analysed quantitatively and qualitatively. The growth of the boride layer Fe2B was examined using optical microscopy (OM), scanning electron microscopy (SEM-EDS) and X-ray diffraction (XRD). The properties were mechanically evaluated, using a Vickers indenter with loads of 0.5 and 1 N, with a constant distance of 15 μm and 30 μm. To determine the fracture toughness (Kc) and the adherence of the boride layer Fe2B, the Rockwell C test method (VDI 3198) was used. The morphology present in the boride Fe2B layer showed a smooth flat, whit ranged thickness from 13.96 ± 1.61 μm to 79.86 ± 4.13 μm. The presence of boride Fe2B layers of steel substrate was confirmed by XRD and the distribution of alloying elements by Energy Disperses for Spectroscopy (EDS). The hardness of the boride layers Fe2B ranged from 157 9± 17 to 1875 ± 25 HV. The fracture toughness of boride Fe2B layer observed ranged from 4.15 to 4.75 MPam1/2. The boride layer has a scale delamination H3 to H6. The boride layers formed in the surface have the function to increase the service life of W2 steels used in the industry.

The evolution of under-ice melt ponds, or double diffusion at the freezing point

1974 ◽  
Vol 64 (3) ◽  
pp. 507-528 ◽  
Author(s):  
Seelye Martin ◽  
Peter Kauffman
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Freezing Point ◽  
Salt Water ◽  
Ice Sheet ◽  
Water Layer ◽  
Double Diffusion ◽  
Theoretical Models ◽  
Interfacial Region ◽  
Ice Melt

In an experimental and theoretical study, we model a phenomenon observed in the summer Arctic, where a fresh-water layer at a temperature of 0°C floats both over a sea-water layer at its freezing point and under an ice layer. Our results show that the ice growth in this system takes place in three phases. First, because the fresh-water density decreases upon supercooling, the rapid diffusion of heat relative to salt from the fresh to the salt water causes a density inversion and thereby generates a high Rayleigh number convection in the fresh water. In this convection, supercooled water rises to the ice layer, where it nucleates into thin vertical interlocking ice crystals. When these sheets grow down to the interface, supercooling ceases. Second, the presence of the vertical ice sheets both constrains the temperatureTand salinitysto lie on the freezing curve and allows them to diffuse in the vertical. In the interfacial region, the combination of these processes generates a lateral crystal growth, which continues until a horizontal ice sheet forms. Third, because of theTandsgradients in the sea water below this ice sheet, the horizontal sheet both migrates upwards and increases in thickness. From one-dimensional theoretical models of the first two phases, we find that the heat-transfer rates are 5–10 times those calculated for classic thermal diffusion.

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