Surface solar cooling through water vapor desorption from photo-responsive sepiolite nanocomposites

Karamanis, D.; Vardoulakis, Ε.; Kyritsi, E.; Okte, Neren

doi:10.1016/j.enconman.2012.01.035

Cited by 10 publications

(4 citation statements)

References 4 publications

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“…porous pillared heterostructures, mesoporous molecular sieves, etc. ), are laboratory prototypes realized in very small quantities due to structure complexity [7]. Thence, the studies regarding building evaporation cooling are mainly focused on natural porous materials with high water uptake capacity, more suitable for large-scale applications on building surfaces.…”

Section: Introductionmentioning

confidence: 99%

Effect of pore modulating additives-sepiolite and colloidal nano silica-on physical, mechanical and durability properties of lime-based renders

et al. 2022

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In hot-humid climates, porous external surfaces of the buildings with high water sorption capabilities could contribute to the surface temperatures reduction through the release of latent heat by evaporative cooling. On the other hand, compact and low permeable finishing materials could have mechanical and durability benefits respect to the underlying supports, for example reducing the permeability to degrading agents. In this paper, the properties of lime base coat renders with pore modulating additives (sepiolite and colloidal nano silica) have been surveyed to evaluate their effectiveness in water absorption, thermal performance, and the fulfilment of mechanical requirements for the application on the external side of the walls. A traditional lime–sand formulation was taken as reference. After preliminary tests on workability and shrinkage, the optimal mix designs were selected and the samples were subjected to several mechanical and thermo-hygrometric tests, before and after accelerated aging. The results allowed demonstrating that the use of sepiolite in substitution of sand, enhances the render ductility, thermal resistance and water uptake but worsens its mechanical stability, increasing the shrinkage effects and slightly reducing the ultimate strength values. The addition of colloidal nano silica, either to lime–sepiolite or to lime–sand renders, fails to produce any improvement in their either physical or mechanical behavior. Mixed formulations (lime–sand with sepiolite and nano silica) behave as simple lime–sand solutions, showing optimal compressive and flexural strength but reduced water uptake capabilities. This demonstrates that the presence of sand prevails in the performance of the render, and that the adoption of other additives doesn’t worth the cost for the benefit presented.

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Section: Introductionmentioning

confidence: 99%

Effect of pore modulating additives-sepiolite and colloidal nano silica-on physical, mechanical and durability properties of lime-based renders

et al. 2022

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“…Some of the studies have reported that moss-greening materials do not exhibit much temperature reducing ability, if they do not contain enough water [23,24]. It is believed to be because the sample’s apparent physical properties, such as specific heat and thermal conductivity, change due to water included in the sample [25], or the sample is deprived of the heat necessary for evaporating water [26,27,28,29]. The influence of moss transpiration may also be included in other factors.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Analyses of Temperature-Reducing-Effect by Heat of Water Evaporation on a Moss-Greening Ceramic Utilizing Waste Silica

et al. 2018

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To recycle silica byproducts and to moderate the heat-island phenomenon, a porous ceramic was prepared by mixing waste silica powder with clay, and then firing the resultant mixture. By exploiting the high water-absorption capacity of the resulting ceramic, a greening material in which the porous ceramic was covered with moss was produced. The suppression effect of the temperature increase caused by solar-radiant heat on the moss-covered ceramic, was investigated quantitatively using the following procedure. First, the surface temperature change of the water-absorbing moss-covered sample during solar-radiant heat reception, and the amount of water that evaporated from the sample were measured simultaneously. Then, the heat of evaporation was estimated from measurements of the rate of water evaporation. Next, to investigate how much the sample temperature was reduced by heat of water evaporation, the temperature change of the sample when the heat of water evaporation was absorbed from the sample, was simulated by performing Finite Element Method (FEM) analysis. The summary of the results was as follows. (1) The primary factor of the temperature-reduction-effects on the moss-covered sample was action of heat of water evaporation. Therefore, the moss-covered sample did not exhibit much of the suppression ability of the temperature increase caused by solar-radiant heat, when the sample did not contain sufficient water. (2) This analytical method enabled us to simulate with a relatively high accuracy, the temperature change of a water-absorbing sample during solar-radiant-heat reception. Especially, the method enabled us to investigate visibly the influence of water evaporation-heat on the sample temperature, in addition to the influences of the emissivity of the sample, and the apparent specific heat and thermal conductivity changes due to water content in the sample.

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“…The principle has been validated with the addition of liquid water in natural porous materials [2], synthetic and aluminum pillared clays [15], modified lignite fly ash [16] and organic polymers [17]. Recently, the principle was applied to moisture sorption on highly hydrophilic natural sepiolite without the addition of liquid water [18]. With moisture adsorption during the night on multiporous sepiolite at 70% relative humidity (RH) (to resemble the outdoor conditions at night), lower surface temperatures were observed under irradiation compared to concrete due to heat absorption for water evaporation and desorption with the accompanied mass reduction [18].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, the principle was applied to moisture sorption on highly hydrophilic natural sepiolite without the addition of liquid water [18]. With moisture adsorption during the night on multiporous sepiolite at 70% relative humidity (RH) (to resemble the outdoor conditions at night), lower surface temperatures were observed under irradiation compared to concrete due to heat absorption for water evaporation and desorption with the accompanied mass reduction [18]. However, the intensity of the applied radiation in these experiments was low.…”

Section: Introductionmentioning

confidence: 99%

Well-ordered nanoporous materials for low-temperature water phase changes and solar evaporative cooling

Karamanis

Kyritsi

Krimpalis

2015

Solar Energy Materials and Solar Cells

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Surface solar cooling through water vapor desorption from photo-responsive sepiolite nanocomposites

Cited by 10 publications

References 4 publications

Effect of pore modulating additives-sepiolite and colloidal nano silica-on physical, mechanical and durability properties of lime-based renders

Effect of pore modulating additives-sepiolite and colloidal nano silica-on physical, mechanical and durability properties of lime-based renders

Experimental and Numerical Analyses of Temperature-Reducing-Effect by Heat of Water Evaporation on a Moss-Greening Ceramic Utilizing Waste Silica

Well-ordered nanoporous materials for low-temperature water phase changes and solar evaporative cooling

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