Humid air is a mixture of dry air and water vapor and is widely used in various power and technical devices. Most theoretical studies of the properties of humid air are based on Mendeleev-Clapeyron ideal gas equa-tion, which doesn’t take into account the association, intermolecular interaction, and particularities of the thermodynamic behavior of humid air as a mixture of gases. The use of this equation leads to inaccuracy in determining the parameters of the state of humid air, which can reach up to 55 %. Therefore, the issues con-cerning the actual properties of humid air determining remain poorly understood. The ideal gas model is based on Mendeleev-Clapeyron equation. To study the actual parameters of the humid air state and its properties, Vukalovich-Novikov’s and Molie’s real gas state equations have been used.Several equations of the state of real gas, taking into account the interaction of water vapor molecules have been considered. The actual physical properties of humid air are determined, and their influence on the coupled heat and mass transfer processes for various conditions is evaluated. The actual values of the thermophysical properties of humid air have been derived. The thermodynamic limits for humid air have been determined using Mendeleev-Clapeyron’s, Vukalovich-Novikov’s and Molie’s state equations. It has been proved Vukalovich-Novikov’s state equation to be the best to represent the quantitative relations between the pressure, specific volume, and the temperature of saturated water vapor. Its application reduces the error of calculations by 39–50 %. The results obtained allow to improve the accuracy of calculating heat and mass transfer when designing contact heat exchangers, convective drying units and hygroscopic desalination plants, compression processes with water or water vapor injection, as well as the processes of mixing flue gases with water vapor in the combustion chambers of gas-steam installations.
The desalination of sea and salty water is one of the alternatives in solving the problem of freshwater recourses shortage. Reverse osmosis and distillation desalination methods are widely used for industrial, household and potable water supply. Each method requires definite energy and material costs. That’s why the problem of developing and researching the most effective energy and financial desalination plants is up to date. The aim of our research is the analysis of self-sufficient hygroscopic desalination plant operation efficiency. The comparative analysis of the most popular desalination methods has been carried out. The authors describe the desalination plant components and its operation principle. The main factors that influence plant intensity are determined. The plant developed efficiency is to increase the performance due to additional steam generation on the basis of steam-gas-liquid balanced condition law. Energy effectiveness increase is reached thanks to heat energy recycling in a condenser-separator and in a fresh water coil. The authors state that one of the best ways to accelerate the hygroscopic desalination process is to increase the initial temperature of water in barbotage area. The plant developed is characterized with high energy effectiveness, low costs and high quality of fresh water obtained.
The growing global shortage of freshwater resources can be partially offset by the desalination of mineralized ocean and marine waters. The most common methods of desalination today are distillation, based on phase transformations of water, and reverse-osmosis, which consists in passing sea water through semipermeable membranes. The distillation method of desalination is characterized by significant thermal energy needs. In the process of desalination by the reverse-osmotic method, there is a need for the periodic replacement of expensive membranes, the creation of high pressure, which leads to significant energy consumption. In this regard, the actual problem is the study of vapor-air desalination method, based on the law of equilibrium state of vapor-gas-liquid mixtures. The efficiency of devices based on the vapor-air method is a significant increase in productivity due to the additional generation of steam, which reduces the energy costs for heating water in the installation. The purpose of this work is to determine the main factors affecting the performance of the vapor-air type installations. As a result of an experimental study of the operation of aself-sufficient steam-type desalination setup, it was found out that the initial water and air temperatures in the bubbling zone have a key impact on the performance. The high energy efficiency of devices implementing this method, with the quality of the condensate that complies with regulatory requirements, makes the vapor-air desalination method very future-oriented.
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