Computational Fluid Dynamics based numerical simulations for achieving Energy-Performance optimization of Large-Scale Outdoor Air Cleaning Systems.

The rising levels of urban air pollution are a matter of serious concern in various parts of the world including India. Airborne Particulate Matter, particularly its component, PM2.5 is the cause of greatest harm to humans. Source control, regulatory compliance and mitigation technologies are the main approaches available to combat urban air pollution. In this regard, Medium Scale Air Cleaning Systems (MSACS) have been installed in two outdoor locations in Delhi to study the feasibility of creating clean air zones in places of higher population density for mitigating PM2.5 levels. These are based on Minnesota design following the initiatives taken by IIT Bombay. The studies are in progress to establish the performance of these systems.

The available design is based on a high throughput downdraft concept in which powerful fans suck the air from a tower top making it pass through charged-fiber filters of large area to filter to remove the PM2.5 and deliver clean air jet at ground level. This jet traverses considerable distance along the downstream direction of the ambient wind flow before being degraded, thereby providing clean air to people going about their daily lives in this zone. CFD based simulations are in progress to establish the range of this zone in the complex urban ecosystem and experimental studies are in progress to compare with model.

In the meantime, a close look at the design of the ACS indicates that this system could be improved significantly in terms of its optimality with respect to the cost-energy-performance. First is the consideration with respect to optimization of power consumed versus flow of the air. A beginning has been made to establish the basic equations to address these questions through an ongoing M.Tech project.

The proposed M. Tech Project for the semester in 2022 intends to take the study forward to include realistic designs, hybridization of power delivery mechanisms, passage through resisting elements such as filters and optimization of clean air delivery arrangements at the exit. Various heating mechanisms will be considered along with the use of solar power to generate air flow. Energy, momentum and mass conservation equations will be solved together using softwares such as Ansys-Fluent. Axi-symmetric and general dimension problems will be addressed in turbulent regimes. The characteristics of the flow generated will be examined systematically with respect to the geometrical, power, and filtration resistance considerations to come-up with an optimal design strategy for future Large Scale Air Cleaners.

In this project, the student will gain experience in applying CFD models to address a very topical, high impact technological approach to a problem of considerable societal relevance.