Abstract
Heat transfer, temperature and velocity fields of droplets of water and aqueous salt solutions have been studied. The initial concentration of salt solutions C01 = 30% in accordance with advanced technological applications. It is shown that the heat flux q for a water droplet is several times higher than for salt solutions. During the droplet evaporation, this difference increases, since q for aqueous salt solutions is many times reduced. While maintaining the wall temperature under the drop quasi-constant (Tw = 83 °C), the heat transfer coefficient α (for the time t < 150 s) for a drop of water 1.5–2 times exceeds α for the salt solution, and is 7 times higher for water than for the salt solution at t = 280 s. Using PIV measurements the liquid velocity fields have been obtained; and for the first time it has been shown that only for very small times and at high ΔT, the important role is played by thermo-gravitational convection in the droplet (the Rayleigh number Ra). But already for t > 10 s, the thermal and solutal Marangoni flows have a greater influence on the flow in a drop of the salt solution.
Original language | English |
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Pages (from-to) | 59-70 |
Number of pages | 12 |
Journal | Experimental Thermal and Fluid Science |
Volume | 99 |
DOIs | |
Publication status | Published - 1 Dec 2018 |
Keywords
- Heat transfer coefficient
- PIV measurements
- Salt solution
ASJC Scopus subject areas
- Chemical Engineering(all)
- Nuclear Energy and Engineering
- Aerospace Engineering
- Mechanical Engineering
- Fluid Flow and Transfer Processes