The influence of characteristic scales of convection on non-isothermal evaporation of a thin liquid layer

Abstract

Here, the effect of convection in liquid on non-isothermal evaporation of a horizontal thin layer on a hot wall is investigated. It is considered that the evaporation rate of salts always decreases with the growth of salt concentration. Depending on the nature of evaporation rate, the aqueous salt solutions can be classified into two different types: (1) the equilibrium partial pressure of water vapor ps varies slightly with time; (2) with an increase in salt mass concentration, ps decreases many times, which leads to a sharp drop in evaporation rate j. The criteria for attributing the salt to characteristic types are proposed, and relation between j and thermodynamic properties of salt solutions is determined. Different approaches to modeling are proposed for each group. For the first time, a simple calculation method linking the Peclet and Marangoni criteria with convection in a liquid and non-stationary heat exchange is proposed. The analysis shows that it is impossible to simulate the heat transfer without knowing the local characteristics of the velocity field in the liquid phase and without clearly distinguishing the characteristic convective scales of the velocity and temperature fields. So far, it has been believed that the surface Marangoni flow can be neglected due to the negative impact of surfactants. However, the studies of this paper show that a noticeable increase in free convection relates to the thermal and solutal Marangoni flows. A strong influence of the Marangoni flow on liquid convection at high heat fluxes is extremely important for reliable simulation of layer evaporation in a wide range of modern technologies.

Modeling of Freon 134a Gas Hydrate Synthesis via Boiling and Condensation of Gas in a Volume of Water

“…Many works study the synthesis of gas hydrates under various conditions including the addition of promoters [10][11][12][13][14][15][16], as well as their dissociation, e.g., during combustion [17][18][19][20]. In this case, a very important aspect is the study of the thermal and convective processes [21,22]. A team of authors is currently developing several original methods for the synthesis of gas hydrates, which are based on the boiling of liquefied gas in a volume of water [23][24][25][26].…”

Study of Enhancement of Synthesis of Freon 134a Gas Hydrate During Boiling of Liquefied Gas with Its Simultaneous Stirring with Water

“…The reason is that the synthesis process itself is nontrivial and complex, effective intensification of which requires taking a set of measures. There are many studies on synthesis of gas hydrates under various conditions [5][6][7][8][9][10][11][12]; it is important to analyze thermal and convective processes [13,14]. The process of gas hydrate decomposition is also complex; there are many respective studies, including those with combustion of the gas released during the dissociation of hydrate [15][16][17][18].…”

Spatiotemporal distribution of the temperature field inside the thin heated foil during impacting liquid spray

“…Over the past few years, one concludes that the effective solution to this challenge is to use a spray liquid cooling system [1]. Several heat transfer mechanisms are important for drop evaporation, namely, convection [2] and evaporation in the contact line. Previous studies showed an extremely high heat flux of 1,2 kW/cm 2 with water spray cooling, which is anticipated to be a key in solving thermal management problems of high-power electronic components because of its efficient heat removal.…”