Free convection and vapor diffusion of droplet aqueous solutions

This paper presents the results of experimental studies of nonisothermal desorption at nucleate boiling of layers of aqueous salt solutions of LiBr and CaCl 2 . The height of the layers is 2.8 mm. The wall temperature is 120 °C. The drop in the temperature of the interfacial surface (T s ) for salt solutions and distillate is associated with low thermal conductivity of the metal wall (titanium) and intense heat flow at nucleate boiling. A heat balance for a free liquid interface has been worked out. In 75 seconds after the beginning of evaporation, the heat flux for aqueous becomes quasi-permanent, and for aqueous salt solutions of CaCl 2 and LiBr, the heat flux continuously decreases with time. This is due to the increase in the salt concentration in the solution and the drop in the equilibrium partial pressure of the vapor.

Section: Experimental Datamentioning

confidence: 99%

“…Phase transformations in heat pumps depend on the heat flux [1,2]. The nonisothermal desorption of aqueous salt solutions at a temperature below boiling was studied in [3][4][5]. Evaporation of pure liquids differs significantly from solutions [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Nonisothermal desorption at nucleate boiling in a layer of aqueous salt solution

Морозов

Elistratov

2019

“…Experimental and theoretical complexity significantly increases in the presence of non-isothermal conditions. Evaporation of liquids was studied in [1][2][3][4], and non-isothermal desorption of saline solutions was considered in [5][6][7]. Evaporation of water-salt solutions of salts is accompanied by an increase in the concentration of salt in solution.…”

Section: Introductionmentioning

confidence: 99%

The dynamics of nucleate boiling of salt solutions at a high heat flux

Морозов

Elistratov

2019

In this paper, experimental results are obtained for the desorption of layers of aqueous salt solutions of LiBr and CaCl 2 at a temperature of nucleate boiling on a horizontal heating surface. The wall temperature is 130 °C. The required volume of the solution with a given mass concentration is placed on the working surface using the Thermo Scientific dispensers. After that, the desorption rate continuously decreases over time. A decrease in the wall temperature leads to a drop in the intensity of the bubbling boiling. The effect of gas convection during evaporation and thermal radiation is small in comparison with the heat of evaporation.

“…Modern technologies commonly use the droplet evaporation. Evaporation of a drop and liquids were studied in [4][5][6][7][8][9][10][11][12][13][14]. Gas-droplet-particles flows are used in an energy sector and allow to solve environmental issues [6].…”

Section: Introductionmentioning

confidence: 99%

Droplet desorption modes at high heat flux

Misyura

Meleshkin

2019

Nonisothermal droplet desorption of aqueous salt solution H 2 O/LiBr during nucleate boiling was studied experimentally. A droplet was placed on a horizontal heated wall. The initial concentration of salt C 0 = 25 %. The wall temperature T w = 120 ºC and ambient air pressure is 1 bar. Thermal images of the temperature field on the droplet surface show an extremely non-uniform temperature field. At nucleate boiling in LiBr salt solution it is incorrect to predict the desorption behavior in stationary approximation. It was previously believed that the rate of evaporation does not vary with time. For the first time it is shown that the desorption rate is divided into several characteristic time intervals. These intervals is characterized by a significant change in the desorption rate.