Evaporation Retardation by Monomolecular Layers: An Experimental Study at the Aji Reservoir (India)

Panjabi, Kishor; Rudra, R. P.; Goel, Pradeep K.

doi:10.4236/ojce.2016.63029

Cited by 12 publications

(6 citation statements)

References 30 publications

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“…Hence the authors attribute the formation of this thin lm layer for the slow evaporation in the case of AGH. Similar observations were also reported in [30][31][32][33][34] . However, some more rigorous experiments may be carried out to understand the formation of thin layer and is out of the scope of present work.…”

Section: Resultssupporting

confidence: 92%

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Cooling enhancement using acacia gum based hydrogel in roof ponds: model room experimental analysis.

Joshi

2022

Preprint

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In this paper we report the observations of outdoor experiments which were carried out to test the cooling effect inside a model room due to evaporation from an acacia gum based hydrogel placed in an aluminium sheet roof pond. Unlike the direct evaporation from roof ponds, the hydrogels resist the evaporation rate and hence the trapped water particles could still provide the cooling effect on the next consecutive day. The experiments had three model rooms with only difference in the roof component: (a) bare aluminium sheet roof – considered as reference, (b) roof pond which contained only water, and, (c) roof pond containing acacia gum based hydrogel which was watered periodically. Two different sets of experiments were carried out: (1) The roof ponds were watered each day around 12 noon and (2) The roof ponds were maintained dry (not watered). In the first set of experiments, no significant difference in the air temperature of the model rooms on the first day was observed. But on the next consecutive day, around 2°C – 4°C difference was observed during the morning hours until both the roof ponds were watered again. The acacia gum and water mixture was used as hydrogel in the present experiments. The dilute solution (around 1:10 ratio) was observed to be reusable for several days without any bio-degradation. The second set of experiments showed that the heat transfer from the edges of the dry roof pond can be significant. The dry roof pond could cause 0.7°C – 1.2°C drop in average room air temperature between 6pm – 6am as compared to that of bare sheet roof. On the other hand, the same was observed to be around 1.3°C to 1.7°C in the case of dry roof pond with dry acacia gum. However, during day time, the room air temperature in the case of dry roof ponds was observed to be higher. Based on the present set of experiments, we concluded that the acacia gum can be a cost effective material for building cooling with reduced evaporation rate and the heat transfer from the edges of the roof pond can be significant.

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Section: Resultssupporting

confidence: 92%

“…A blend of C18OH and C18E1 (50:50 ratio) was recommended by the authors to observe a relatively thick viscous lm formed over the free surface. A mixture of cetyl and stearyl alcohol (1:1 ratio) over the water surface was experimented by Panjabi et al 34 ; around 19.3% reduction in evaporation was observed.…”

Section: Introductionmentioning

confidence: 99%

Cooling enhancement using acacia gum based hydrogel in roof ponds: model room experimental analysis.

Joshi

2022

Preprint

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“…Verlee and Zetland (2015) examined powder monolayers, such as hexadecanol and octadecanol on the surface of Lake Arrowhead in United States, and achieved a water evaporation reduction of 15%. Panjabi et al (2016) spread the hybrid monolayer of Cetyl and Stearyl alcohol on the water surface and concluded that the utilized monolayer could prevent water evaporation by 19%.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of hydrophobic bentonite effects on reducing evaporation from water surfaces

Jajin

Feizi

Ghorbanpour

2022

Journal of Hydrology and Hydromechanics

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In recent years, due to the occurrence of water shortage and drought problems, particularly in arid and semi-arid regions of the world, new methods to reduce evaporation from the surface of dam reservoirs, lakes, and other water-free surfaces are investigated. This study aimed to use hydrophobic bentonite to reduce water evaporation from water surfaces, on a laboratory scale, and field conditions for the first time. Bentonite initially became hydrophobic by stearic acid (SA). Under such conditions, hydrophobic bentonite floats on the surface of water and forms a thin coating layer. The produced hydrophobic bentonite had a contact angle of 150°, indicating its superhydrophobicity. Evaporation reduction was measured under laboratory and field conditions and it was compared to hexadecanol as the reference material. The results demonstrated that the hydrophobic bentonite efficiency under laboratory conditions was similar to that of hexadecanol and prevented water evaporation by 36%. However, under field conditions, hydrophobic bentonite and hexadecanol efficiencies were 40% and 23% to reduce evaporation for 30 days, respectively. In terms of stability, hexadecanol needed to be re-injected after three days, while hydrophobic bentonite was stable and remained on the surface for more than 100 days under laboratory conditions and for more than 15 days under field conditions without needing re-injection. This coverage with method can be used to reduce evaporation from lakes, tanks, and reservoirs of small dams.

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“…Over the past 50 years, several chemical films and monolayers have been produced and commercialized. Many countries such as Brazil (Panjabi et al 2016), Australia (Roberts 1957), Singapore (Babu et al 2010), Turkey (Sophiane and Djamel 2012) and USA (Wixson 1967), have used monolayers to suppress the evaporation from their dams and water reservoirs.…”

Section: Introductionmentioning

confidence: 99%

Effect of Wind Flow and Solar Radiation on Functionality of Water Evaporation Suppression Monolayers

Mozafari

Mansouri

Chini

2019

Water Resour Manage

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The average evaporation in Iran is 3 times higher than the world average. Applying chemical monolayers on water surfaces is one of the promising methods for suppressing the evaporation. Literature studies have shown that the mixture of cetyl and stearyl (ratio of 1 to 9) is the state-of-the-art monolayer to minimize the evaporation. Adding calcium hydroxide increases the spreading rate and self-healing of the monolayer. Despite long study and investigation on monolayers, there are inconsistencies in explaining the mechanism by which monolayers decrease the evaporation. The mechanisms used to explain the evaporation reduction are: (i) increasing the reflected solar radiation, (ii) dampening the waves formed by winds and decreasing the water surface area, consequently, and (iii) limiting the escape of water molecules. In this paper, by design of experiments (DOE), we try to answer the above question. Evaporation rate from a container in absence of wind or low wind (~0.2 m/s) and at moderate temperature and relative humidity (~20 °C and 45%) is ~10 mm/day. Utilization of the monolayer can save 41% of the evaporated water. Also, in absence of radiation, a 9 m/s wind caused ~15 mm/day evaporation. By increasing the wind speed from 0 to 9 m/s, effectiveness of the monolayer deteriorated from 60 to 13%. Therefore, the main mechanism is neither reflecting the radiation (as in absence of radiation, monolayer was still effective) nor dampening the waves and decreasing the surface area (as in absence of wind, monolayer was effective; also, at higher wind speeds where the surface area increases, monolayer efficiency decreases). Therefore, the main mechanism by which monolayers decrease the evaporation rate is limiting the escape of water molecules. So, monolayers may be effective even during the nights even though radiation is at its lowest.

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Evaporation Retardation by Monomolecular Layers: An Experimental Study at the Aji Reservoir (India)

Cited by 12 publications

References 30 publications

Cooling enhancement using acacia gum based hydrogel in roof ponds: model room experimental analysis.

Cooling enhancement using acacia gum based hydrogel in roof ponds: model room experimental analysis.

Experimental investigation of hydrophobic bentonite effects on reducing evaporation from water surfaces

Effect of Wind Flow and Solar Radiation on Functionality of Water Evaporation Suppression Monolayers

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