Influence region theory of the evaporating droplet. (February 2019)

• Record Type: Journal Article
• Authors: Zhao, Fulong; Liu, Qianfeng; Zhao, Chenru; Bo, Hanliang
• Is Part Of: International journal of heat and mass transfer. Volume 129(2019)
• Page Start: 827
• Page End: 841
• Publication Date: 2019-02
• Subjects: Influence region -- Droplet evaporation -- Two-way coupling -- Source terms -- Euler-Lagrange approach; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2018.09.124
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: The influence region concept of the evaporating droplet is put forward. Numerical simulation of water droplet evaporation in hot air is conducted. The dimensionless radius of influence region on Condition No. 2 is about 30. The expression of influence region radius is obtained by curve fitting. Abstract: The coupling mechanism between the evaporating droplet and surrounding gas is a challenging topic for heat and mass transfer of two phase flow. Generally, the mass, momentum and heat source terms are added to gas conservation equations to describe the action of the droplet on gas phase. However, usually, the source terms are only imposed to just the fluid mesh where the droplet is located, which can lead to the computation divergence. Therefore, this research tries to study the influence of the droplet on the fluid field to figure out the two-way coupling mechanism. The numerical simulation of the water droplet evaporation in hot air under is conducted based on VOF model, which reveals that only the specific fluid field region surrounding the droplet can be influenced by the droplet. The concept of influence region of the evaporating droplet is proposed based on theoretical analysis. Within influence region, parameters of the gas surrounding the droplet change dramatically due to the effects of the droplet. However, outside influence region, the effect can be neglected. In addition, numerous simulations are conducted to analyze the influence factors of influence region. The analysis reveals that the influence region has a radius about 30 times the droplet radius under condition No. 2. The influence region radius increases with increasing droplet radius, temperature difference and with decreasing operating pressure, the air humidity. Finally, the expression of the influence region radius is obtained by data fitting.