Seawater desalination using sunlight is a sustainable freshwater production, which contributes the solution of global water shortage. This solar desalination has generally three steps; conversion of ...solar energy to heat, vaporization of seawater by the heat and condensation of water vapor to form freshwater. We have studied a seawater desalination using two-ply membrane system, where a dye modified hydrophilic membrane is put on a hydrophobic one. When seawater loaded on the system is exposed to sunlight, desalinated water is obtained under the hydrophobic membrane by the membrane permeation of water vapor. This paper reports the improvement of the third step, condensation of water vapor, of our process, which is indispensable for the efficient production of freshwater. When Al petri dish, heatsink and cooling plate were equipped under the two-ply membrane system, the recovery of the vaporized water was remarkably improved by promoting the condensation of water vapor using those devices. Next, capillary action with hydrophilic membrane wick was applied for long term operation of the process with continuous supply of seawater. Finally, a three-ply membrane system, where black light-absorbing sheet, hydrophilic membrane wick and PTFE membrane were stacked, was found to be effective for the mass production of freshwater.
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•Condensation step of water vapor in solar desalination was improved.•The improvement was achieved using Al petri dish, heatsink and cooling plate.•The improved condensation remarkably increased recovered desalinated water.•Three-ply membrane system with capillary action was active for solar desalination.
Atmospheric water generation (AWG) is a technological innovation that facilitates the extraction of water from the atmosphere using various techniques. In response to mounting concerns regarding ...water scarcity in multiple regions globally, AWG has emerged as a promising solution for providing potable water in areas where conventional water sources are limited or contaminated. AWG systems can be implemented across diverse settings, ranging from individual households to large-scale industrial operations, and can be powered by renewable energy sources. Despite the inherent challenges associated with upscaling AWG technology to ensure its affordability and reliability, it possesses the potential to make a significant contribution towards meeting the water requirements of communities in both developed and developing nations. This study aimed to investigate the performance and limitations of a commercially available dehumidifier, namely, the Trotec TTK140S (Heinsberg, Germany), through experimental analysis. Additionally, the feasibility of integrating this dehumidifier with a photovoltaic energy source was explored. Initially, the dehumidifier’s water production and energy consumption were assessed under specific conditions. Subsequently, a comparison was conducted across three different locations (Lisbon, Pretoria, and Riyadh) to evaluate the dehumidifier’s operation and ascertain the photovoltaic module area necessary for it to function independently. This approach effectively addresses one of the main drawbacks of the technology, namely, its substantial energy consumption.
This article presents experimental research on hygrothermal conditions in a historic wooden church in southern Poland. The scope of the research included the continuous monitoring of temperature and ...relative humidity in several measuring plots in different areas inside and outside of the church. We also continuously monitored the number of people attending services. This study presents a detailed analysis of the development of heat and humidity conditions within the church. A model of the object was developed, and a computational analysis of the risk of condensation of water vapor on the inner surface of the partitions was carried out. An analysis of the results showed a large variation in the temperature and humidity conditions in the church. The internal temperature ranged from −9.7 to 25.9 °C, and the relative humidity of the indoor air ranged from 45.6% to 91.6%. The test results showed that the temperature and humidity of the indoor air periodically exceeded the accepted values of thermal comfort for historic buildings. The analysis of the obtained research results showed that the humidity and humidity conditions in the church mainly depend on the climatic zone and the number of people participating in the services. Moreover, an analysis of the results showed no risk of condensation on the wooden partitions of the church, but it should be noted that the temperature of the partitions was subject to rapid fluctuations (from −8.0 to 24.6 °C), which may have a negative impact on these historic wooden objects.
We consider a system of equations that describes the air motion inside tropical cyclones, including consequences of the condensation of water vapor. We examine the system of nonlinear ordinary ...differential equations on wind trajectories in the plane of radial and vertical variables. We prove the unique solvability of the system of differential equations on a segment suitable for modeling of tropical cyclones.
The article deals with comparison of three wall systems. One of the structural systems is conventional and the two others systems are among the Modern Methods of Construction (MMC). For comparison ...the endpoints were: thermal balance and condensation of water vapor. The thickness of the wall structures and the individual layers are modelled to meet the recommended amount of heat transfer coefficient Ur1. When this requirement is met, the condensation of water vapor in the wall structures is further analyzed. The aim is to determine whether, during the cycle of a year the balance of water vapor is negative and where is the location of condensation in the wall of the MMC wall construction used in Slovakia. The result of the investigation will be a comparison of selected structures and evaluating the most advantageous wall structure of selected construction systems.
An experimental design of a condensing economizer has been developed to increase the energy efficiency of traditional-type gas boilers. An experiment was conducted, as a result of which data were ...obtained that made it possible to draw a conclusion about the effectiveness of its use for individual heat supply of residential and public buildings. Technical solutions have been obtained that improve the efficiency of obtaining the latent heat of condensation of water vapor from flue gases. The presented results can be especially useful under real operating conditions of heat exchangers. This in turn ensures the safe and reliable operation of engineering systems as a whole.
Cloud droplets grow on cloud condensation nuclei (CCN) with condensing the ambient water vapor in the atmospheric air parcel. The size of the cloud droplet in the equilibrium state is estimated ...usually by Köhler Equation. However, Köhler Equation is based on the assumption that the cloud droplet grows in an infinitely large reservoir of water vapor at constant pressure, i. e., at constant saturation ratio. This assumption causes some erroneous results in the estimation of real size in the air parcel, although the assumption makes the calculation easy. There are two apparent deficiencies in Köhler Equation. One is that the equilibrium size cannot be decided in case of the larger saturation ratio than the critical ratio. The other is that the variation of the size with the number density of CCN, i. e., the competitive growth, cannot be considered in the estimation of the size. In order to improve these deficiencies, the conventional Köhler Equation has been modified using the mass conservation of the water contained in the air parcel.
In order to investigate the effect of the drop-phase oxidation due to rainout (in cloud scavenging) of gaseous air pollutants on the acidification of cloud droplets, the characteristics of the ...acidification of a growing cloud droplet by the rainout of SO2 (g) are simulated numerically with use of a mathematical model based on physicochemical consideration.(NH4) 2SO4is selected for the cloud condensation nucleus (CCN), which is a major aerosol and produced from NH3 (g) and SO2 (g) via gas-phase chemical reaction in the atmosphere. With use of the model the droplet radius and the concentrations of chemicals are simulated. It is shown that with lapse of time the hydrogen ion concentration continues to increase beyond the equilibrium concentration (obtained in the case without the oxidation) and that a plateau appears in the concentration profile.
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