The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Tiefeng Chen - One of the best experts on this subject based on the ideXlab platform.
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thermal characteristics of dry Cooling Tower reconstructed from obsolete natural draft wet Cooling Tower and the relevant thermal system coupling optimization
Applied Thermal Engineering, 2020Co-Authors: Wenjing Ge, Yuanbin Zhao, Wendong Li, Shiwei Song, Tiefeng ChenAbstract:Abstract Natural draft dry Cooling Tower is attractive in recent decades with its superiority of zero water loss. Some old thermal power plants are under high pressure of waste water reducing emission, thus the natural draft wet Cooling Tower is obsoleted. Reconstructing natural draft wet Cooling Tower into natural draft dry Cooling Tower is attractive for the saving of capital expenditure. But it has not been researched before, this study aims to fill this gap. Based on an actual reconstruction case, the operation mode of reconstructed dry Cooling system is established and relevant MATLAB programming is realized, which was validated by literature data. The reconstructed system consists of two reconstructed natural draft dry Cooling Towers, a usual natural draft dry Cooling Tower and two 660 MW power units. The Cooling capacity of reconstructed natural draft dry Cooling Tower is lower through thermal characteristic comparison with the usual natural draft dry Cooling Tower. In order to realize the optimal operation, different water distribution schemes are presented and several operation parameters are analyzed. Under the optimized reconstruction design, the annual water saving and annual cost are discussed. The annual water saving is about14.49 million metric tons that is about 8.86 million dollars and the minimum annual cost is about 181.47 million dollars, which brings great economic and environmental benefits.
Mantheerapol Kuansathan - One of the best experts on this subject based on the ideXlab platform.
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comparative evaluation of hybrid dry wet Cooling Tower performance
Applied Thermal Engineering, 2014Co-Authors: Wanchai Asvapoositkul, Mantheerapol KuansathanAbstract:Abstract The performance of hybrid Cooling Tower is analyzed using experiments and numerical simulations on a wide variety of working conditions. A computational model for predicting the behavior of dry, wet and hybrid Cooling systems has been developed. The hybrid Cooling Tower model is expressed as a combination of a dry Cooling model and a wet Cooling model. The effectiveness-NTU equation and the Merkel equation, fundamental equation of heat transfer in dry and wet Cooling Towers, are presented and discussed. The Cooling Tower characteristics are a function of water-to-air ratio for each Cooling mode. Comparison of the model Tower test results with those of a computer simulation has demonstrated the validity of that simulation and its use as a design tool. Using the information presented in this paper, it will be possible to incorporate dry and wet Cooling Tower design, and simulation into a procedure to evaluate and optimize hybrid Cooling Tower performance.
Wenjing Ge - One of the best experts on this subject based on the ideXlab platform.
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thermal characteristics of dry Cooling Tower reconstructed from obsolete natural draft wet Cooling Tower and the relevant thermal system coupling optimization
Applied Thermal Engineering, 2020Co-Authors: Wenjing Ge, Yuanbin Zhao, Wendong Li, Shiwei Song, Tiefeng ChenAbstract:Abstract Natural draft dry Cooling Tower is attractive in recent decades with its superiority of zero water loss. Some old thermal power plants are under high pressure of waste water reducing emission, thus the natural draft wet Cooling Tower is obsoleted. Reconstructing natural draft wet Cooling Tower into natural draft dry Cooling Tower is attractive for the saving of capital expenditure. But it has not been researched before, this study aims to fill this gap. Based on an actual reconstruction case, the operation mode of reconstructed dry Cooling system is established and relevant MATLAB programming is realized, which was validated by literature data. The reconstructed system consists of two reconstructed natural draft dry Cooling Towers, a usual natural draft dry Cooling Tower and two 660 MW power units. The Cooling capacity of reconstructed natural draft dry Cooling Tower is lower through thermal characteristic comparison with the usual natural draft dry Cooling Tower. In order to realize the optimal operation, different water distribution schemes are presented and several operation parameters are analyzed. Under the optimized reconstruction design, the annual water saving and annual cost are discussed. The annual water saving is about14.49 million metric tons that is about 8.86 million dollars and the minimum annual cost is about 181.47 million dollars, which brings great economic and environmental benefits.
Wanchai Asvapoositkul - One of the best experts on this subject based on the ideXlab platform.
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comparative evaluation of hybrid dry wet Cooling Tower performance
Applied Thermal Engineering, 2014Co-Authors: Wanchai Asvapoositkul, Mantheerapol KuansathanAbstract:Abstract The performance of hybrid Cooling Tower is analyzed using experiments and numerical simulations on a wide variety of working conditions. A computational model for predicting the behavior of dry, wet and hybrid Cooling systems has been developed. The hybrid Cooling Tower model is expressed as a combination of a dry Cooling model and a wet Cooling model. The effectiveness-NTU equation and the Merkel equation, fundamental equation of heat transfer in dry and wet Cooling Towers, are presented and discussed. The Cooling Tower characteristics are a function of water-to-air ratio for each Cooling mode. Comparison of the model Tower test results with those of a computer simulation has demonstrated the validity of that simulation and its use as a design tool. Using the information presented in this paper, it will be possible to incorporate dry and wet Cooling Tower design, and simulation into a procedure to evaluate and optimize hybrid Cooling Tower performance.
Sharon G. Berk - One of the best experts on this subject based on the ideXlab platform.
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Aspects of Cooling Tower Biocides and Protozoa
Corrosion, 1998Co-Authors: Sharon G. Berk, R.j. Ashburn, Rebecca S. TingAbstract:Previous work has shown that certain Cooling Tower amoebae and ciliated protozoa are resistant to several Cooling Tower biocides, even at the manufacturer`s recommended dosages. For the present study, an Acunthumoeba species was isolated from a Cooling Tower in Australia. Suspensions of the trophozoites (feeding stages) were exposed to isothiazolones. Cysts were tested separately. The minimum lethal concentration (MLC) for trophozoites was between 31-62 ppm of the biocide product, which is slightly less than the MLC for an amoebae species from the United States; and cyst forms were twofold more resistant than those of the US species, with a MLC of 62,500 ppm. A ciliate and an amoeba species were also exposed to bromochlorodimethylhydantoin. The MLC for the ciliate species was 1 ppm of the biocide product, and the MLC was 30--40 ppm for the amoeba trophozoites. Since amoebae can expel vesicles containing live Legionella, experiments were conducted to determine whether exposure of Acunthamoebu polyphugu to biocides influenced release of such potentially infectious particles. Vesicle release was not inhibited by any of the three biocides: quaternary ammonium compounds (QACs), isothiazolones, and a thiocarbamate compound. These results suggest that amoebae from various sources are resistant to recommended levels of biocides, andmore » the amoebae may continue to release potentially infectious vesicles in the presence of biocides.« less
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Survival of protozoa in Cooling Tower biocides
Journal of Industrial Microbiology & Biotechnology, 1996Co-Authors: E E Sutherland, Sharon G. BerkAbstract:Protozoa from Cooling Towers may serve as hosts for legionellae, but such protozoa have not been examined with respect to effects of Cooling Tower biocides. In this study, two ciliate species,Tetrahymena sp andColpoda sp, and two amoebae species,Vannella miroides andAcanthamoeba hatchetti, were isolated from a Cooling Tower and tested for survival in the presence of four Cooling Tower biocides. The protozoa were exposed for 24 h to a thiocarbamate compound, an isothiazolone compound, quaternary ammonium compounds (QAC), and tributyltin neodecanoate with quarternary ammonium compounds (TBT/QAC). After exposure, cells were examined for viability. The highest concentration of each biocide in which cells could survive was compared to the manufacturers' recommended maintenance dosage (MRMD) of the biocides.Tetrahymena andColpoda survived concentrations within the range of the MRMD of thiocarbamate and QAC.Vannella andAcanthamoeba survived concentrations within the MRMD of thiocarbamate, isothiazolone, and QAC.Colpoda cysts andAcanthamoebae cysts remained viable after exposure to concentrations much greater than the MRMD of thiocarbamate, isothiazolone, and QAC. None of the protozoa in any stage could survive the MRMD of TBT/QAC. These results show that protozoa indigenous to Cooling Towers may survive the recommended concentration of certain biocides, and this information may be important in devising procedures for eradicating hosts for legionellae.
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Adaptation of Amoebae to Cooling Tower Biocides
Microbial Ecology, 1994Co-Authors: Santhanam Srikanth, Sharon G. BerkAbstract:Adaptation of amoebae to four Cooling Tower biocides, which included a thiocarbamate compound, tributyltin neodecanoate mixed with qua- ternary ammonium compounds (TBT/QAC), another QAC alone, and an isothiazolin derivative, was studied. Previously we found that amoebae iso- lated from waters of Cooling Towers were more resistant to Cooling Tower biocides than amoebae from other habitats. Acanthamoeba hatchetti and Coch- liopodium bilimbosum, obtained from American Type Culture Collection and used in the previous studies, were tested to determine whether they could adapt to Cooling Tower biocides. A. hatchetti was preexposed to subinhibitory con- centrations of the four biocides for 72h, after which they were tested for their resistance to the same and other biocides. C. bilimbosum was exposed to only two biocides, as exposure to the other two was lethal after 72 h. Preexposure to the subinhibitory concentrations of the biocides increased the resistance of the amoebae, as indicated by a significant increase in the minimum inhibitory concentration (up to 30-fold). In addition, cross-resistance was also observed, i.e., exposure to one biocide caused resistance to other biocides. These results show that amoebae can adapt to biocides in a short time. The phenomenon of cross-resistance indicates that regularly alternating biocides, as is done to control microbial growth in Cooling Towers, may not be effective in keeping amoeba populations in check. On the contrary, exposure to one biocide may boost the amoebae's resistance to a second biocide before the second biocide is used in the Cooling Tower. Since amoebae may harbor Legionella, or alone cause human diseases, these results may be important in designing effective strategies for controlling pathogens in Cooling Towers.
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Stimulatory effect of Cooling Tower biocides on amoebae.
Applied and Environmental Microbiology, 1993Co-Authors: Santhanam Srikanth, Sharon G. BerkAbstract:Two species of amoebae were isolated from the Cooling Tower of an air-conditioning system and examined for effects of exposure to four Cooling Tower biocides, a thiocarbamate compound, tributyltin neodecanoate mixed with quaternary ammonium compounds, another quaternary ammonium compound alone, and an isothiazolin derivative. The amoebae isolated were Acanthamoeba hatchetti and a Cochliopodium species. Two other amoeba cultures, an A. hatchetti culture and Cochliopodium bilimbosum, were obtained from the American Type Culture Collection (ATCC) and were also tested. The Cooling Tower isolates were more resistant to most of the biocides than the ATCC isolates were. The isothiazolin derivative was the least inhibitory to all four amoeba isolates, and tributyltin neodecanoate mixed with quaternary ammonium compounds was the most inhibitory to three of the four isolates. After exposure to lower concentrations of the biocides, including for one strain the manufacturer's recommended concentration of one biocide, the Cooling Tower amoeba populations increased significantly compared with unexposed controls, whereas the ATCC isolates were not stimulated at any of the concentrations tested. In some cases, concentrations which stimulated Cooling Tower amoebae inhibited the growth of the ATCC isolates. These results suggest that Cooling Tower amoebae may adapt to biocides, underscoring the need to use freshly isolated Cooling Tower organisms rather than organisms from culture collections for testing the efficacy of such biocides. The stimulatory effect of biocides on amoeba populations is an alarming observation, since these organisms may be reservoirs for legionellae. Biocides used to control microbial growth may actually enhance populations of host organisms for pathogenic bacteria.