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International Heat Transfer Conference 16

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

EVAPORATION FROM THIN POROUS MEDIA WITH MIXED WETTABILITY

Rui Wu
Shanghai Jiao Tong University, 800 Dongchuan Rd. Minhang District, Shanghai 200240, China

Changying Zhao
Research Center of New Energy and Energy Storage, China-UK Low Carbon College, Shanghai Jiao Tong University, Shanghai 200240, China; Institute of Engineering Thermophysics, Shanghai Jiao Tong University, Shanghai 200240, China

DOI: 10.1615/IHTC16.pma.022414
pages 8009-8021


KEY WORDS: Boiling and evaporation, Porous media, gas diffusion layer, capillary valve effect, pore network model

Abstract

A pore network model is developed to understand the evaporation processes in the thin porous media with mixed wettability. The pore network is composed of cubic pore bodies connected by cylindrical pore throats. The vapor transport in the pore network is controlled by the mass diffusion; the liquid flow is taken as the fully developed laminar flow. The capillary valve effect induced by the sudden geometrical expansion at the interface between the pore throat and the pore body is considered. Because of the capillary valve effect, two types of invasion into the pore body is revealed. One is bursting invasion, and the other is merging invasion. In the case of dominant bursting invasion, there are two types of gas invasion patterns during the two-phase transport processes in the pore network. The first is the throat to body type, i.e., once a pore throat is invaded, its neighboring pore body will be invaded immediately. The second is the body to throat type, i.e., once a pore body is invaded, its neighboring pore throats will be invaded in the following steps. The gas invasion pattern is controlled by both the wettability and structure of the pore network. The effects of the mixed wettability are explored in detail on the evaporation processes in different structural pore networks.

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