Wastewater and Agricultural Aeration Efficiency
Treatment of drinking and wastewater consumes an estimated 3-4% of all energy use in the United States, and a large portion of this is devoted to aerating the wastewater stream, allowing micro-organisms to digest organic matter using cellular respiration. In order to accomplish this, an adequate supply of oxygen is required, and the best way to do this, currently, is using bubble diffusers. Here, air is forced through a membrane, creating tiny bubbles which increase surface-area and hence, oxygen transfer from air to water. There are inherent problems with this practice, first and foremost the fact that blowers or compressors must supply the air, which are fundamentally inefficient. There are two distinct projects underway in this research area: First, we are performing numerical simulations to prove that there exists an optimal bubble size and diffuser depth for wastewater aeration, which can hopefully set a standard practice for aeration operations. Secondly, ACELab members have developed a novel, patented aeration device, called a Confined Tube Aerator or CTA, which incorporates a Venturi aspirator to a coiled tube in which bubbles are naturally drawn in. Here, oxygen is transferred inside the tube, which increases bubble residence time simultaneously eliminating the need for air compressors. The CTA device is expected to be especially useful for aquaculture aeration, where bubble diffusers are not possible due to pond dredging practices.
Adaptive Airfoil Design for Improved Aerodynamic Performance
Bio-mimicry, a practice where complex problems are solved using naturally found systems or elements, is a fascinating subject which has given rise to many recent engineering feats, from common aerodynamic forms to the shape of treads on automobile tires. One astonishingly effective biological system is the means by which fish and ceatacians swim, where propulsive efficiencies are often far greater than any propellors constructed by humans. Using inspiration from this motion, the morphing or adaptive airfoil concept is being studied for improved aerodynamic performance. Recent studies indicate that these passively flexible airfoils help to reduce stall as well as increase operational range and lift-drag ratio, with possible implications in small Reynolds number flight such as micro-air or unmanned aerial vehicles.
Flexible blade design for wind and wave energy conversion
Many engineering devices are designed to operate optimally at a specific set of conditions, termed the "design point". As an unfortunate side effect of this design practice, wind turbine efficiency can drop drastically in varying wind loads, especially so when speeds fall outside the operational envelope. This project involves flexible blade design for wind turbines, wherein the blade acts as a passive pitch control mechanism, effectively adjusting its geometry in response to varying loading. This adaptability has proven to offer two major advantages over rigid blade designs: 1) higher efficiency, especially away from the design point, and 2) an increased operational envelope, allowing for greater energy capture especially in locations experiencing high wind variance.
Thermal Energy Storage
Electricity is produced mainly from power-plants operating at steady state. When demand spikes other means must be used to provide the additional supply with little notice, usually coming from the burning of fossil fuels at low efficiency. In hot climates, these spikes are often the result of air conditioners working to provide space cooling. Thermal Energy Storage (TES) is an effective strategy in these locations to save energy costs and decrease greenhouse gas emissions. This research involves design and analysis of ice TES systems, which can be used to create cooling storage at night using low cost electricity. This TES storage can later be used during high energy demand times, reducing operational costs and overall peak demand. We are also looking at using the same thermodynamic principles applied to Concentrated Solar Power (CSP) systems, where storage of high temperature thermal energy is essential for providing base electricity loads.
Computational Continuum Mechanics
Many problems of interest in engineering involve the interaction of fluids and solids. When simulating Fluid-Structure interaction (FSI) problems it is often convenient to segregate solvers, often leading to difficulty in coupling and/or convergence. This is due to the inherent strengths of the Finite-Volume (FV) method in fluid solvers and the Finite-Element (FE) method in solid solvers. This research involves employing and augmenting open-source codes to simulate problems of interest using both FE and FV methods for "mostly solid" and "mostly fluid" applications, respectively. Our main goal is reducing both design and computational costs when compared to commercially available codes.
We are also interested in all areas involving renewable and clean energy conversion, as well as various other topics in fluid and solid mechanics, thermodynamics, heat transfer and system optimization.