Research

Flow characterization of milled biomass and waste materials

Municipal solid wastes and biomass materials like trees and crops can be converted to energy products and have been considered as one of the most promising alternatives for energy and fuels due to their abundance and easy access. However, the commercialization of bioenergy and waste-to-energy has been significantly constrained by severe issues during the handling of particulate biomass and waste materials, manifested as unstable flow and jamming in handling equipment such as hoppers, feeders, or conveyors. Solving these issues centers on the mechanistic understanding of the flowability of milled biomass and waste materials and their rheological and constitutive behaviors in various industrial equipment.

This project investigates the flow behavior of biomass and solid waste particles across different scales: 1) particle porous structure and its effects on flowability, 2) meso-scale flow behavior, 3) granular flow in handling equipment like hoppers and screw feeders.

This project improves fundamental understanding of the flow physics of biomass and solid waste materials and enables the development of the next-generation high-efficiency handling equipment to reduce the cost and increase the safety of feedstock processing.

Constitutive modeling for granular flow in quasi-static and dense-flow regimes

Granular materials can behave like solids (e.g., sand pile at rest) or liquids (e.g., slurry and dense particle flow) depending on their shear rate. In fast flow applications like landslides and material handling, the behavior of granular materials often shifts between the two regimes. Particles interact by both friction and collision and shear responses depend on both shear strain and shear rate.

This project studies the multi-regime flow behavior of loblolly pine chips. Inclined plane experiments were conducted to evaluate the flow behavior, and a cross-regime constitutive model was developed and validated against the experiments. The scaling law of biomass flowing on an inclined plane was explored. 

Enhanced shallow geothermal systems with microencapsulated phase change materials

The efficiency of shallow geothermal energy recovery has been constrained by both the short-term temperature anomaly around heat exchangers and the long-term ground heat depletion.

This study numerically investigates the thermal performance of energy piles enhanced by micro-encapsulated phase change materials (mPCM). The results show that thermal performance can be evidently improved by mixing small proportions of mPCM in the ground to utilize its latent heat, and the temperature influence zone is significantly shrunk.