Calcium Carbonate Formation on Cross-Linked Polyethylene (PEX) and Polypropylene Random Copolymer (PP-r)

2005 ◽  
Vol 128 (2) ◽  
pp. 251-254 ◽  
Author(s):  
Patricia Sanft ◽  
Lorraine F. Francis ◽  
Jane H. Davidson
Keyword(s):  
Calcium Carbonate ◽  
Random Copolymer ◽  
Reynolds Numbers ◽  
Unit Surface Area ◽  
Carbonate Concentration ◽  
Carbonate Formation ◽  
Unit Surface ◽  
Before And After ◽  
Polymer Tubes ◽  
Polypropylene Random Copolymer

The accumulation of calcium carbonate (referred to as scale) on the surface of cross-linked polyethylene and polypropylene random copolymer tubes is compared to that on copper. Water with total calcium and carbonate concentration of 3×10−3M and a pH of approximately 9.1, yielding a supersaturation of 7.8, was pumped through the tubes at a velocity of 0.07m∕s for 2.5, 5, and 7.5h. Flow was laminar with Reynolds numbers of <1000. Sections of the tubes were analyzed at the designated time points to determine the extent of scaling. Results include scanning electron microscope images of the tube surfaces before and after exposure to the supersaturated water and chemical analysis to determine the mass of calcium carbonate per unit surface area. Measured scaling rates of the two polymer tubes are similar to that of copper.

Scaling in Polymer Tubes Used in Solar Water Heating Systems

Solar Energy ◽  
2004 ◽  
Author(s):  
Yana Wang ◽  
Jane H. Davidson ◽  
Lorraine F. Francis
Keyword(s):  
Calcium Carbonate ◽  
Heat Exchangers ◽  
Tap Water ◽  
Hard Water ◽  
Unit Surface Area ◽  
Solar Absorbers ◽  
Nylon 6,6 ◽  
Before And After ◽  
Glycol Solution ◽  
Polymer Tubes

An experimental study of the growth of calcium carbonate (commonly termed scaling) on copper, nylon 6,6, semiaromatic high temperature nylon, polypropylene, polybutylene, and Teflon tubes exposed to hard water is presented. The objective of the study is to gain qualitative information on the scaling of polymer tubes in nonisothermal, flowing conditions expected in heat exchangers and solar absorbers. The 89-cm long tubes were placed in tube-in-shell heat exchangers. Water prepared from 10 °C tap water with a total calcium concentration of 4×10−3 M, and a pH of 9.0 was pumped through the tubes at 4 cm/s. A 50 percent propylene glycol solution at 60 °C was maintained on the shell-side of the heat exchanger. The experiment was carried out for 540 hours with these conditions. Sections of the tubes were removed periodically to determine the extent of scaling. Results include scanning electron microscope images of the tube surfaces before and after exposure to the flowing water, X-ray diffraction to determine the crystalline phase content of the observed deposits, and chemical analysis to determine the mass of calcium carbonate per unit surface area and to estimate the scaling rate. A model of the scaling process is presented to help interpret the data. The data show conclusively that polymer tubes are prone to scaling. With the exception of nylon 6,6, the scaling rate on the polymers is about the same as that on copper. The nylon 6,6 substrate appears to enhance scaling.

Scaling in Polymer Tubes and Interpretation for Use in Solar Water Heating Systems

2005 ◽  
Vol 127 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Yana Wang ◽  
Jane Davidson ◽  
Lorraine Francis
Keyword(s):  
Heat Exchangers ◽  
Tap Water ◽  
Hard Water ◽  
Unit Surface Area ◽  
Flowing Water ◽  
Nylon 6,6 ◽  
Before And After ◽  
Pretreatment Phase ◽  
Glycol Solution ◽  
Polymer Tubes

An experimental study of the growth of scale on copper, nylon 6,6, semiaromatic high temperature nylon, polypropylene, polybutylene, and Teflon tubes exposed to hard water is presented. Results provide qualitative information on the scaling of polymer tubes in nonisothermal, flowing conditions expected in heat exchangers and solar absorbers. The 89-cm-long tubes were placed in tube-in-shell heat exchangers. The tubes were exposed to flowing water for 1660 h, a 1120-h pretreatment phase using tap water adjusted to supersaturation of about 2 and pH of 8, followed by a 540-h acceleration phase using tap water with an adjusted total calcium concentration of 4×10−3M, and a pH of 9. Flow rate was 4 cm/s. A 50% propylene glycol solution at 60°C was maintained on the shell side of the heat exchanger. Sections of the tubes were removed periodically to determine the extent of scaling. Results include scanning electron microscope images of the tube surfaces before and after exposure to the flowing water, x-ray diffraction to determine the crystalline phase content of the observed deposits, and chemical analysis to estimate the mass of calcium carbonate per unit surface area. A model of the scaling process is presented to help interpret the data. The data show conclusively that polymer tubes are prone to scaling. With the exception of nylon 6,6, the scaling rate on the polymers is about the same as that on copper. The nylon 6,6 substrate appears to enhance scaling. The enhancement is attributed to hydrolysis of the substrate.

scholarly journals CHARACTERISTICS OF WAVES BROKEN BY A LONGSHORE BAR

1970 ◽  
Vol 1 (12) ◽  
pp. 26 ◽  
Author(s):  
E. Clark McNair ◽  
Robert M. Sorenson
Keyword(s):  
Wave Height ◽  
Unit Surface Area ◽  
Dimensional Model ◽  
Surface Time ◽  
Unit Surface ◽  
Before And After ◽  
Equivalent Wave ◽  
Time Histories ◽  
Different Depths ◽  
Incident Waves

A two-dimensional model submerged offshore bar was installed in a Texas A&M Hydrodynamics Laboratory wave tank Monochromatic waves with a range of heights and periods were generated at this bar for three different depths of water over the bar For each wave, water surface time-histories were measured at points before and after the bar and spectral analyses of these measurements were performed The analysis of each wave record yielded an equivalent wave height which is proportional to the square root of the wave energy per unit surface area The ratio of the reformed to incident equivalent wave height is shown to relate to the ratio of incident wave height to water depth over the bar The predominant periods of the reformed waves are found to be the same as for the incident waves but the presence of energy at higher frequencies is also observed The cause of these higher frequency waves is discussed.

The Cylindrical Electrostatic Liquid Film Radiator for Heat Rejection in Space

1994 ◽  
Vol 116 (4) ◽  
pp. 986-992 ◽  
Author(s):  
H. Kim ◽  
S. G. Bankoff ◽  
M. J. Miksis
Keyword(s):  
Waste Heat ◽  
Heat Pipes ◽  
Reynolds Numbers ◽  
Viscous Drag ◽  
Unit Surface Area ◽  
Unit Surface ◽  
Micrometeorite Impact ◽  
Present Design ◽  
New Space ◽  
Liquid Flows

A new space radiator concept has been proposed (Kim et al., 1991, 1992a, b, 1993) in which a thin film of hot liquid, flowing along the inside of a closed membrane, rejects waste heat by radiation to the surroundings. In previous versions, the radiator rotates, supplying most of the driving force for the liquid flow. In the present design, the cylinder is stationary, and the liquid flows circumferentially under its initial momentum. Moderately large Reynolds numbers are required to overcome viscous drag, and prevent excessive thickening of the film. The major design consideration involves the application of an internal electrostatic field to pull the liquid away from the site of a membrane puncture due to micrometeorite impact. Calculations are presented that show that leaks can be stopped with a safety factor of two or more, while the surface wave thus produced is washed harmlessly out of the system. Some preliminary heat transfer performance characteristics are presented. The advantages of this concept include the absence of moving parts and the ease of deployment, compared to rotating units, and a factor of at least three for the reduction of the weight per unit surface area compared to heat pipes.

NON-DESTRUCTIVE EXPERIMENTS AND MODELING OF CALCIUM CARBONATE FORMATION IN SOILS

2020 ◽  
Author(s):  
Carolyn D. Bland ◽  
◽  
Timothy M. Gallagher ◽  
Daniel O. Breecker
Keyword(s):  
Calcium Carbonate ◽  
Carbonate Formation ◽  
Non Destructive

scholarly journals The Influence of Finely Ground Mineral Admixture (FGMA) on Efflorescence

2013 ◽  
Vol 4 (1) ◽  
pp. 50-55 ◽  
Author(s):  
Ong Ming Wei ◽  
Norsuzailina Mohamed Sutan
Keyword(s):  
Calcium Carbonate ◽  
Chemical Analysis ◽  
Mineral Admixture ◽  
Partial Replacement ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Cement Replacement ◽  
Carbonate Formation

Efflorescence phenomenon on concrete is not new and found in the form of white deposits on surfaces of concrete. Incorporation of Finely Ground Mineral Admixture (FGMA) in concrete to prevent occurrence of efflorescence is based on reduction of portlandite, densified microstructure and thus enhanced watertightness. The magnitude of efflorescence in term of percentage of calcium carbonate formation of FGMA modified mortar were evaluated at water-cement ratio of 0.3, 0.4 and 0.5 with 10%, 20%, and 30% of cement replacement by weight. The samples were tested with chemical analysis at 7, 14, 21, 28, 60 and 90 days. The FGMA additions into mortar were comparing with ordinary mortar to evaluate enhanced performance of FGMA modified mortar toward efflorescence. The results of this experiment showed that addition of FGMA into mortar caused less formation of calcium carbonate as partial replacement of cement with certain w/c ratio and percentage of cement replacement.

scholarly journals Mpemba Effect- the Effect of Time

2021 ◽  
Author(s):  
Jianan Wang
Keyword(s):  
Gravitational Field ◽  
Surface Area ◽  
Time Effect ◽  
Light Quantum ◽  
Unit Surface Area ◽  
Heat Flows ◽  
Unit Surface ◽  
Average Wavelength ◽  
Nature Of Time ◽  
The Relationship

This paper draws the following conclusions on the nature of time by analyzing the relationship between time and speed, the relationship between time and gravitational field, the gravitational redshift of the photon, and the black-body radiation theorem: Time on an object is proportional to the amount of energy flowing out (or in) per unit time (observer’s time) per unit surface area of the object. When an object radiates energy outward: t'=μB(T) =μσT 4=μnhν/st Where t’ is the time on the object, μ is a constant, B(T) is the radiosity，the total energy radiated from the unit surface area of the object in unit time (observer’s time), σ is the Stefan-Boltzmann constant, T is the absolute temperature, n is the number of the photons radiated, ν is the average frequency of the photons radiated, s is the surface area of the object and t is the time on the observer. When the object radiates energy outward, the higher the energy density of the space (for example the stronger the gravitational field of the space), the smaller the radiosity B(T) of the object in the space, the longer the average wavelength of the light quantum emitted by the object, the slower the time on the object, the longer the life of the system. When the object radiates energy outward, the faster the object moves relative to the ether, the higher the energy density of the local space in which the object is located, the smaller the radiosity B(T) of the object, the longer the average wavelength of the light quantum radiated by the object, the slower the time on the object, and the longer the life of the system. When the object radiates energy outward, the higher the temperature of the object, the greater the object's radiosity B(T), the shorter the average wavelength of the light quantum radiated by the object, the faster the time on the object, and the shorter the life of the system. Applying the above conclusions about the nature of time, the author analyzes the Mpemba effect and the inverse Mpemba effect, and reaches the following conclusion: the Mpemba effect is the time effect produced when heat flows from objects into space, and the "inverse" Mpemba effect is the time effect produced when heat flows from space into objects.

Structural characterization of amorphous calcium carbonate-binding protein: an insight into the mechanism of amorphous calcium carbonate formation

2013 ◽  
Vol 453 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Jingtan Su ◽  
Xiao Liang ◽  
Qiang Zhou ◽  
Guiyou Zhang ◽  
Hongzhong Wang ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Binding Sites ◽  
Binding Protein ◽  
Homology Modelling ◽  
Size Exclusion ◽  
Structural Basis ◽  
Amorphous Calcium Carbonate ◽  
Carbonate Formation

ACC (amorphous calcium carbonate) plays an important role in biomineralization process for its function as a precursor for calcium carbonate biominerals. However, it is unclear how biomacromolecules regulate the formation of ACC precursor in vivo. In the present study, we used biochemical experiments coupled with bioinformatics approaches to explore the mechanisms of ACC formation controlled by ACCBP (ACC-binding protein). Size-exclusion chromatography, chemical cross-linking experiments and negative staining electron microscopy reveal that ACCBP is a decamer composed of two adjacent pentamers. Sequence analyses and fluorescence quenching results indicate that ACCBP contains two Ca2+-binding sites. The results of in vitro crystallization experiments suggest that one Ca2+-binding site is critical for ACC formation and the other site affects the ACC induction efficiency. Homology modelling demonstrates that the Ca2+-binding sites of pentameric ACCBP are arranged in a 5-fold symmetry, which is the structural basis for ACC formation. To the best of our knowledge, this is the first report on the structural basis for protein-induced ACC formation and it will significantly improve our understanding of the amorphous precursor pathway.

Long-term experimental study of the aquatic plant system for polluted river water

2002 ◽  
Vol 46 (11-12) ◽  
pp. 217-224 ◽  
Author(s):  
K. Sato ◽  
H. Sakui ◽  
Y. Sakai ◽  
S. Tanaka
Keyword(s):  
Surface Area ◽  
Aquatic Plant ◽  
Aquatic Macrophyte ◽  
Unit Surface Area ◽  
Artificial Wetlands ◽  
Polluted River ◽  
Plant System ◽  
Unit Surface ◽  
Experimental Facilities

Water purification using artificial wetlands and aquatic macrophyte is attracting attention as a purification technology that can create rich ecosystems while imposing a minimal load on the environment. Because an aquatic plant system requires a large surface area, design specifications and maintenance methods that can obtain the optimum purification effect per unit surface area must be established. Large experimental facilities have been constructed beside a polluted river flowing into Lake Kasumigaura and have been used for a three-year experiment using several kinds of aquatic plants. This report summarizes the characteristics and the design load of the aquatic plant system based on this study and results from other aquatic plant facilities.

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