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.

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.

A Comparison of Hand Washing Techniques To Remove Escherichia coli and Caliciviruses under Natural or Artificial Fingernails

2003 ◽  
Vol 66 (12) ◽  
pp. 2296-2301 ◽  
Author(s):  
CHIA-MIN LIN ◽  
FONE-MAO WU ◽  
HOI-KYUNG KIM ◽  
MICHAEL P. DOYLE ◽  
BARRY S. MICHAELS ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Tap Water ◽  
Hand Washing ◽  
Microbial Populations ◽  
Liquid Soap ◽  
E Coli ◽  
Hand Sanitizer ◽  
Before And After ◽  
Escherichia Coli Jm109 ◽  
Viral Indicators

Compared with other parts of the hand, the area beneath fingernails harbors the most microorganisms and is most difficult to clean. Artificial fingernails, which are usually long and polished, reportedly harbor higher microbial populations than natural nails. Hence, the efficacy of different hand washing methods for removing microbes from natural and artificial fingernails was evaluated. Strains of nonpathogenic Escherichia coli JM109 and feline calicivirus (FCV) strain F9 were used as bacterial and viral indicators, respectively. Volunteers with artificial or natural nails were artificially contaminated with ground beef containing E. coli JM109 or artificial feces containing FCV. Volunteers washed their hands with tap water, regular liquid soap, antibacterial liquid soap, alcohol-based hand sanitizer gel, regular liquid soap followed by alcohol gel, or regular liquid soap plus a nailbrush. The greatest reduction of inoculated microbial populations was obtained by washing with liquid soap plus a nailbrush, and the least reduction was obtained by rubbing hands with alcohol gel. Lower but not significantly different (P &gt; 0.05) reductions of E. coli and FCV counts were obtained from beneath artificial than from natural fingernails. However, significantly (P ≤ 0.05) higher E. coli and FCV counts were recovered from hands with artificial nails than from natural nails before and after hand washing. In addition, microbial cell numbers were correlated with fingernail length, with greater numbers beneath fingernails with longer nails. These results indicate that best practices for fingernail sanitation of food handlers are to maintain short fingernails and scrub fingernails with soap and a nailbrush when washing hands.

scholarly journals Possibilities of heat energy recovery from greywater systems

2018 ◽  
Vol 30 ◽  
pp. 03003 ◽  
Author(s):  
Kaja Niewitecka
Keyword(s):  
Waste Water ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Tap Water ◽  
Residential Building ◽  
Heat Energy ◽  
Alternative Source ◽  
Recovery System ◽  
Heat Recovery System ◽  
Sewage Systems

Waste water contains a large amount of heat energy which is irretrievably lost, so it is worth thinking about the possibilities of its recovery. It is estimated that in a residential building with full sanitary fittings, about 70% of the total tap water supplied is discharged as greywater and could be reused. The subject of the work is the opportunity to reuse waste water as an alternative source of heat for buildings. For this purpose, the design of heat exchangers used in the process of greywater heat recovery in indoor sewage systems, public buildings as well as in industrial plants has been reviewed. The possibility of recovering heat from waste water transported in outdoor sewage systems was also taken into consideration. An exemplary waste water heat recovery system was proposed, and the amount of heat that could be obtained using a greywater heat recovery system in a residential building was presented. The work shows that greywater heat recovery systems allow for significant savings in preheating hot tap water, and the rate of cost reimbursement depends on the purpose of the building and the type of installation. At the same time, the work shows that one should adjust the construction solutions of heat exchangers and indoor installations in buildings to the quality of the medium flowing, which is greywater.

scholarly journals Impact of cleaning regimes on dental water unit contamination

2011 ◽  
Vol 9 (4) ◽  
pp. 647-652 ◽  
Author(s):  
Soad A. Abdallah ◽  
Ahmed I. Khalil
Keyword(s):  
High Speed ◽  
Tap Water ◽  
Daily Basis ◽  
Dental Chair ◽  
Dental Clinics ◽  
Significant Difference ◽  
Before And After ◽  
Hand Piece ◽  
Viable Bacteria ◽  
Dental Unit Waterlines

Microorganisms that have been identified in dental unit waterlines (DUWLs) are of concern because they can cause infections, especially in immunocompromised patients. This study aimed to assess the incidence of microbial contamination in DUWLs before and after intervention to reduce contamination, and to investigate the presence of coliforms, Escherichia coli and Pseudomonas aeruginosa. Water samples were collected aseptically from the waterlines. The high-speed hand-piece and dental chair units were served by one distillation apparatus, which was fed by the potable tap water of four dental clinics. Different interventions were used: chlorination, flushing before clinics and between patients, draining at the end of the day, and freshly distilled water on a daily basis. There was a significant difference between the level of contamination in the high-speed hand-piece (1.5–2.7 log CFU/ml) and dental chair unit water (2.0–3.5 log CFU/ml). Coliforms (0.9%) E. coli (0.9%) and Pseudomonas (1.8%) were detected during 2008. This study indicates the need to monitor water quality regularly and prevent stagnation in DUWLs to reduce the number of viable bacteria to &lt;100 CFU/ml. We recommend flushing the DUWL for 2 min before the first patient and for 10–20 s between patients, flushing the dental unit at the end of the day and draining it overnight to reduce the development of biofilms, and chlorination of the DUWLs.

scholarly journals Bowel preparation for performing a colonoscopy: prospective randomized comparison study between a low-volume solution of polyethylene glycol and bisacodyl versus bisacodyl and a mannitol solution

2012 ◽  
Vol 49 (2) ◽  
pp. 162-168 ◽  
Author(s):  
Manoel Carlos Vieira ◽  
Claudio Lyoiti Hashimoto ◽  
Flair José Carrilho
Keyword(s):  
Polyethylene Glycol ◽  
Vital Signs ◽  
Abdominal Distension ◽  
Similar Efficacy ◽  
Preparation Methods ◽  
Gold Standard Method ◽  
Mannitol Solution ◽  
Before And After ◽  
Glycol Solution

CONTEXT: Colonoscopy is currently the gold standard method to examine the colon, the rectum and the terminal ileum. In order to perform the colonoscopy, it is necessary to clean the bowel and use medications that are generally poorly tolerated by the patients. OBJECTIVE: Compare the tolerability, acceptability, safety and efficacy of two solutions used for intestinal preparation for a colonoscopy. METHODS: One hundred patients matched for sex and age were prospective randomized into two groups. Polyethylene glycol group received bisacodyl 10 mg plus 1 L of polyethylene glycol the night before and 1 L on the day of the exam. Mannitol group received bisacodyl 20 mg the day before and 1 L of a 10% mannitol solution on the day of the exam. The diet was the same for both groups. Tolerability and acceptability were measured using previously validated questionnaires. In terms of safety, variations in vital signs before and after the preparation were recorded, in addition to any complications. The quality of the preparation was graded based on the Boston and Ottawa scales. RESULTS: Ninety-six percent (96%) completed the study. As for tolerability, the mannitol preparation group exhibited a significantly higher frequency of nausea, vomiting, abdominal pain, and abdominal distension than polyethylene glycol group (P < 0.05). Acceptability was significantly better in polyethylene glycol group. The polyethylene glycol solution has also previously been shown to be safer than mannitol. No difference was observed in the quality of the preparation between the two preparation methods. CONCLUSIONS: The following conclusions can be made: polyethylene glycol solution had higher tolerability, acceptability, and safety than the mannitol and should be used instead of mannitol. Both preparation solutions have similar efficacy.

scholarly journals Insecticidal effects of insecticide, fungicide, complex fertilizer and wetting agent combinations depending on water hardness

2009 ◽  
Vol 24 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Slavica Vukovic ◽  
Dusanka Indjic ◽  
Vojislava Bursic ◽  
Dragana Sunjka ◽  
Mila Grahovac
Keyword(s):  
Colorado Potato Beetle ◽  
Tap Water ◽  
Biological Effects ◽  
Water Hardness ◽  
Hard Water ◽  
Wetting Agent ◽  
Simultaneous Occurrence ◽  
Agricultural Practice ◽  
Potato Beetle ◽  
Novi Sad

Simultaneous occurrence of different harmful species in agricultural practice necessitates that different plant protection chemicals be applied at the same time (tank mix). Mix components differ in purpose, mode of action and/or formulation, while addition of no pesticide components (complex fertilizers, adjuvant and wetting agents) is widely practiced today. However, data concerning the effects of water quality used for preparation of working liquids on the biological effects of pesticides is still scarce. Therefore, the objective of this study was to determine insecticidal effects as depending on components used in mixes and water hardness. The effects of mixtures of thiametoxam (Actara 25-WG 0,07kg/ha) with azoxystrobin (Quadris 0.75 l/ha), mancozeb (Dithane M-70 2.5 kg/ha), a complex fertilizer (Mortonijc plus 3 kg/ha) and a wetting agent (Silwet L-77), depending on the components and water hardness (slightly hard (15.4 d?) - tap water from Novi Sad, and very hard (34.7 d?) - well water from Adica, a Novi Sad suburb), were determined in a bioassay based on adult mortality rate of the first generation of Colorado potato beetle (Leptinotarsa decemlineata Say). The mixtures were applied by a flooding method. The trial was set up to include four replications. Insecticidal effects were determined 24 h and 48 h after exposure. Thiametoxam effectiveness 24 h and 48 h after application in slightly hard water was 100% when the insecticide was applied alone and in double and triple mixes with the fungicides, complex fertilizer and wetting agent, showing no dependency on mix components. The tested adult population of Colorado potato beetle demonstrated high susceptibility to thiametoxam, while the other components had no impact in slightly hard water. In very hard water, 24 h after application, the insecticidal effect had the same level of significance to thiametoxam in double and triple mixes, with an exception of thiametoxam+mancozeb+Mortonijc plus and thiametoxam+mancozeb+wetting agent combinations, which showed significantly lower efficacy. After 48 h, substantially lower effectiveness, in comparison with the sole insecticide and other combinations, was only observed in thiametoksam+mancozeb+Mortonjic plus combination. Significantly lower efficacy of that combination is probably due to an incompatibility of the macozeb preparation and the complex fertilizer containing boron (B), which was evidenced only in very hard water.

Pseudomonacidal Activity of Phenolic Disinfectants in Hard Water

1974 ◽  
Vol 57 (4) ◽  
pp. 880-884
Author(s):  
Murray Winicov ◽  
William Schmidt ◽  
Muriel Palochak
Keyword(s):  
High Activity ◽  
Active Ingredient ◽  
Total Phenolics ◽  
Tap Water ◽  
Hard Water ◽  
Total Phenolic ◽  
Magnesium Ions ◽  
Testing Laboratories ◽  
Confirmation Test ◽  
Test Organisms

Abstract Claims for pseudomonacidal activity under use conditions must be validated by hard water performance. Effective phenolic products can be formulated by using o-phenylphenol (OPP) as the principal active ingredient. In tap water containing calcium or magnesium ions, OPP is more effective than any high phenol coefficient phenolic ingredient. Such OPP compositions as are properly formulated with high activity phenolics require a use-dilution concentration providing at least 450 ppm OPP and not less than 750 ppm total phenolics to pass the AOAC use-dilution confirmation test, 4.011, against the 3 principal test organisms in the presence of 400 ppm hard water. Phenolic-based disinfectant products, providing use-dilution OPP concentrations up to 600 ppm and total phenolic concentrations up to 900 ppm, with validated hard water claims are now commercially available. An OPP standard formula is proposed which can be diluted to provide pass/fail usedilutions–a step in the direction of achieving uniformity among different testing laboratories.

Acid dissolution of synthetic aluminous goethite before and after transformation to hematite by heating

Clay Minerals ◽  
1995 ◽  
Vol 30 (1) ◽  
pp. 55-65 ◽  
Author(s):  
H. D. Ruan ◽  
R. J. Gilkes
Keyword(s):  
Surface Area ◽  
Heating Temperature ◽  
Dissolution Kinetics ◽  
Frequency Factor ◽  
Dissolution Time ◽  
Unit Surface Area ◽  
Acid Dissolution ◽  
Al Substitution ◽  
Before And After ◽  
Kinetics Of

AbstractMeasurements of the kinetics of acid dissolution of synthetic aluminous goethites and corresponding hematites produced by heating of parent Al-goethites at various temperatures were carried out in 1 M HC1 at 30, 40 and 50°C. Dissolution-time curves show sigmoidal shapes for the goethites (110°C), whereas deceleratory shapes were obtained for most of the partly and fully dehydroxylated samples. The dissolution rate for all materials decreased with increasing Al substitution and increased with increasing dissolution temperature, specific surface area and heating temperature. On a unit surface area basis, hematite dissolved ∼ 2–8 times faster than goethite. Dissolution kinetics of most heated goethite samples (200–260°C) were quite well described (R2 > 0.96) by the modified first-order Kabai equation. The activation energy and frequency factor for dissolution increased with increasing Al substitution.

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