Bibliography - Zhong Zheng

1. Al-Housseiny, Talal, Peichun Tsai, Zhong Zheng, and Howard Stone, 2011: The effect of permeability gradients on immiscible displacement in Hele-Shaw flows. American Physical Society,
   [ Abstract ]

   In heterogeneous media, it is well known that when a fluid of high viscosity displaces a less viscous fluid, the interface can still be unstable and exhibit finger-like patterns due to capillary fingering. Motivated by porous media flows in natural geological formations, we consider homogeneous displacement in a Hele-Shaw cell subjected to a permeability gradient. The permeability gradient is introduced by linearly varying the Hele-Shaw cell depth. We study how capillary forces can affect interfacial stability in the presence of the gradient via linear stability analysis. Depending on the system, we find that surface tension can either have a stabilizing or a destabilizing role. We report the emergence of an important dimensionless parameter--the ratio of the permeability gradient to the capillary number--that determines the stability of the interface along with the well-studied viscosity ratio. Experiments testing the theoretical findings will also be presented.

2. Zheng, Zhong, Eric Larson, Z. Li, Guangjian Liu, and Robert H. Williams, 2010: Near-term mega-scale CO₂ capture and storage demonstration opportunities in China. Energy and Environmental Science, The Royal Society of Chemistry, 3(9), doi:10.1039/B924243K 1153-1169
   [ Abstract ]

   China is unique in the large number (nearly 400) of existing and planned projects for making ammonia, methanol, and other fuels and chemicals from coal. A natural by-product of these processes is a nearly pure CO₂ stream. Collectively, these facilities will emit (once all are operating) some 270 million tonnes of CO₂ per year. Taking advantage of the relatively low cost of capturing these CO₂ streams (as compared with capturing CO₂ from power plant flue gases), some of the 20 large-scale CO₂ capture and storage (CCS) demonstration projects called for by the leaders from the G8 to be deployed during the next decade might be expeditiously located in China. Our analysis identifies 18 coal-chemicals/fuels facilities, each emitting one million tonnes/year or more of CO₂, that are within 10 km of prospective deep saline aquifer CO₂ storage sites and an additional 8 facilities within 100 km. The potential CO₂ storage basins are identified based on work by others. We adapted two published cost models for CO₂ compression and transport to develop preliminary estimates of prospective costs for potential CCS projects in China. Our "N^th plant" cost estimates for the 18 projects where the CO₂ source is within 10 km of a sink, are between $9 and $13/tonne of CO₂. (The highest cost estimate among all evaluated projects was less than $21/tonne of CO₂.) The 10-year net-present value cost for projects ranged from $89 million to $1.15 billion, with more than 75% of the projects having net present value costs of $200 million or less. These relatively modest CCS costs suggest that there would be mutual value in international cooperation to support CCS demonstrations in China.

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