Circulating Water Systems

1996 ◽  
pp. 353-384
Author(s):  
David J. Brill
Keyword(s):  
Water Systems ◽  
Circulating Water

Effect of heat flushing on the concentrations of Legionella pneumophila and other heterotrophic microbes in hot water systems of apartment buildings

1996 ◽  
Vol 42 (8) ◽  
pp. 811-818 ◽  
Author(s):  
Outi M. Zacheus ◽  
Pertti J. Martikainen
Keyword(s):  
Water Temperature ◽  
Legionella Pneumophila ◽  
Heterotrophic Bacteria ◽  
Water System ◽  
Water Systems ◽  
Hot Water ◽  
Circulating Water ◽  
Heterotrophic Microbes ◽  
Before And After ◽  
Circulating Water System

The decontamination of Legionella pneumophila and other heterotrophic microbes by heat flushing in four legionellae-positive hot water systems was studied. Before the decontamination procedure, the concentration of legionellae varied from 3.0 × 10−3 to 3.5 × 10−5 cfu/L and the hot water temperature from 43.6 to 51.5 °C. During the contamination the temperature was raised to 60–70 °C. All taps and showers were cleaned from sediments and flushed with hot water twice a day for several minutes. The decontamination lasted for 2–4 weeks. In a few weeks the heat-flushing method reduced the concentration of legionellae below the detection limit (50 cfu/L) in the hot circulating water system just before and after the heat exchanger. The high hot water temperature also decreased the viable counts of heterotrophic bacteria, fungi, and total microbial cells determined by the epifluorescent microscopy. However, the eradication of legionellae failed in a water system where the water temperature remained below 60 °C in some parts of the system. After the decontamination, the temperature of hot water was lowered to 55 °C. Thereafter, all the studied hot water systems were recolonized by legionellae within a few months, showing that the decontamination by heat flushing was temporary. Also, the contamination of other bacteria increased in a few months to the level before decontamination.Key words: legionellae, hot water system, decontamination, water temperature, heterotrophic bacteria.

Maintenance of Simulium Wilhelmia lineatum Meigen and Simulium erythrocephalum de Geer through successive generations in the laboratory

1984 ◽  
Vol 62 (5) ◽  
pp. 870-877 ◽  
Author(s):  
P. J. Ham ◽  
A. E. Bianco
Keyword(s):  
Egg Production ◽  
Blood Feeding ◽  
Water Systems ◽  
Feeding Rates ◽  
Fertility Rates ◽  
Bovine Blood ◽  
Circulating Water ◽  
Development Period ◽  
Successive Generations ◽  
Egg Fertility

With the use of circulating water systems to rear larvae, Simulium erythrocephalum and S. lineatum have been continuously maintained through to the F7 and F3 generations, respectively. Insemination rates of 100% were obtained for both species by the F2 generation. Using chick skin membranes and bovine blood, mean blood-feeding rates of 56 and 87% were achieved for S. lineatum and S. erythrocephalum, respectively. Mean egg production and egg fertility rates increased after the parental generation was produced. Mating trials were peformed to assess conditions for optimum insemination rates. A significant correlation between temperature and complete generation development period was observed.

Circulating Water Systems without Valves

1972 ◽  
Vol 98 (2) ◽  
pp. 187-199
Author(s):  
Rudolf J. Wahanik
Keyword(s):  
Water Systems ◽  
Circulating Water

Nonionic Surfactants as Drag Reducing Additives to Circulating Water Systems

1993 ◽  
Vol 30 (3) ◽  
pp. 174-178
Author(s):  
I. Harwigsson ◽  
A. Khan ◽  
M. Hellsten
Keyword(s):  
Nonionic Surfactants ◽  
Water Systems ◽  
Circulating Water

Circulating Water Systems

2015 ◽  
pp. 443-454
Author(s):  
Bahman Zohuri ◽  
Patrick McDaniel
Keyword(s):  
Water Systems ◽  
Circulating Water

Prospects for improvement of refinery circulating water systems

1974 ◽  
Vol 10 (9) ◽  
pp. 668-671
Author(s):  
K. Z. Saifutdinov ◽  
�. G. Ioakimis ◽  
A. K. Efimova
Keyword(s):  
Water Systems ◽  
Circulating Water

Surface Vortex Simulation at Selected Water Temperatures

2011 ◽  
Author(s):  
Aljazˇ Sˇkerlavaj ◽  
Andrej Lipej ◽  
Jure Ravnik ◽  
Leopold Sˇkerget
Keyword(s):  
Turbulence Model ◽  
Power Plants ◽  
Experimental Testing ◽  
Turbulence Models ◽  
Water Systems ◽  
Mean Value ◽  
Circulating Water ◽  
Strong Surface ◽  
Intake Structure ◽  
Surface Vortex

Circulating water systems (CW) and safety water systems (SW) in various power plants use vertical pumps to pump water from pump intakes. A properly designed pump intake structure prevents the occurrence of strong surface vortices, which might inhibit the proper functioning of the pump. Although several standards for experimental testing of pump intake structure suitability exist, our goal is to find a way to predict such vortices numerically, from a single-phase simulation. In such a process, we had already eliminated some of the turbulence models. In the current paper we confirm that Scale Adaptive Simulation (SAS) turbulence model with the curvature correction (CC) factor applied is well suited for such flows. By using a methodology for determining the vortex air core length, the SAS-CC turbulence model results were compared to the experimental data for two selected temperatures. The results show better agreement than the laminar simulations in terms of higher mean value accuracy and lower scattering.

scholarly journals Experimental study on thermal performance in three-flow cooling tower

2020 ◽  
Vol 329 ◽  
pp. 03007
Author(s):  
Ilnur Madyshev ◽  
Ildar Sabanaev ◽  
Vitaly Kharkov ◽  
Lenar Ganiev ◽  
Andrey Dmitriev
Keyword(s):  
Experimental Study ◽  
Thermal Performance ◽  
High Performance ◽  
Cooling Tower ◽  
Water Systems ◽  
Cooling Towers ◽  
Industrial Water ◽  
Cross Sectional ◽  
Circulating Water ◽  
Wetting Rate

Biofouling can significantly deteriorate the efficiency of cooling towers. A cooling tower with a three-flow cooling circuit has been developed. The fill pack consists of inclined-corrugated contact elements with perforation. One of the advantages of the proposed cooling tower is the possibility of uniform distribution of liquid over the cross-sectional area. The paper represents the results of an experimental study of the thermal performance of the three-flow cooling tower. It was found that when the wetting rate of the liquid increases, the thermal performance of the cooling tower can reach 47.8%. The developed three-flow cooling tower allows excluding the propagation of microorganisms and reducing the biofouling of industrial water systems along with the high performance for circulating water.

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