Engineering Commons^™

Research Experiences Instrument: Validation Evidence For An Instrument To Assess The Research Experiences Of Engineering Ph.D. Students’ Professional Practice Opportunities, Eric A. Holloway, Kerrie A. Douglas, David F. Radcliffe, William C. Oakes

School of Mechanical Engineering Faculty Publications

Background. There are long-held concerns about how graduate research programs prepare engineering Ph.D. students for professional practice. Suitable instruments are lacking to effectively assess how research experiences contribute to the success of graduate students becoming professionals.

Purpose. The purpose of this work is to examine evidence of internal reliability and validity of using the Research Experiences Instrument (REI) scores as a measure of engineering Ph.D. students’ professional practice opportunities in their research experiences.

Method. REI was constructed using an ontological framework. REI was administered twice to engineering Ph.D. students, once to a single university (n = 236) and …

Nanofluids Improve Energy Efficiency Of Membrane Distillation, Harsharaj B. Parmar, Hamid Fattahi Juybari, Yashwant S. Yogi, Sina Nejati, Ryan M. Jacob, Prashant S. Menon, David M. Warsinger

School of Mechanical Engineering Faculty Publications

Thermal desalination of high salinity water resources is crucial for increasing freshwater supply, but efficiency enhancements are badly needed. Nanomaterial enhancements offer enormous potential for improving promising technologies like membrane distillation (MD). However, while many approaches have been tried, such as nanoparticle solar absorbers or nanomaterial membranes, there have not been studies to directly enhance the fluid properties in MD; via nanofluids. In this work, we examine nanofluids for gap-based MD systems, including the role of nanoscale physics and system-level energy efficiency enhancements. Our model includes the dominant micro-mixing from Brownian motion in fine particle nanofluids (copper oxide) and the …

Stable Thermally-Modulated Nanodroplet Ultrasound Contrast Agents, Anastasiia Vasiukhina, Javad Estraghi, Adib Ahmadzadegan, Craig J. Goergen, Pavlov P. Vlachos, Luis Solorio

School of Mechanical Engineering Faculty Publications

Liquid perfluorocarbon-based nanodroplets are stable enough to be used in extravascular imaging, but provide limited contrast enhancement due to their small size, incompressible core, and small acoustic impedance mismatch with biological fluids. Here we show a novel approach to overcoming this limitation by using a heating–cooling cycle, which we will refer to as thermal modulation (TM), to induce echogenicity of otherwise stable but poorly echogenic nanodroplets without triggering a transient phase shift. We apply thermal modulation to high-boiling point tetradecafluorohexane (TDFH) nanodroplets stabilized with a bovine serum albumin (BSA) shell. BSA-TDFH nanodroplets with an average diameter under 300 nanometers showed …

Vapor-Selective Active Membrane Energy Exchanger For High Efficiency Outdoor Air Treatment, Andrew J. Fix, James E. Braun, David M. Warsinger

School of Mechanical Engineering Faculty Publications

As much as 40% of the total load on air conditioning systems can be attributed to condensation dehumidification. However, new water vapor-selective membranes present a unique opportunity to greatly reduce the power requirements for moisture removal by avoiding phase change and have thus been ranked as a top alternative to traditional HVAC systems. To date, however, all such systems have relied on the assumption of constant temperature, even terming the technology “isothermal dehumidification.” This work proposes a membrane-based air cooling and dehumidification approach, referred to as the Active Membrane Energy Exchanger (AMX), which is the first to provide simultaneous, yet …

Double-Acting Batch Reverse Osmosis Configuration For Best-In-Class Efficiency And Low Downtime, Sandra Cordoba, Abhimanyu Das, Jorge Leon, Jose M. Garcia, David M. Warsinger

School of Mechanical Engineering Faculty Publications

Energy consumption in reverse osmosis has decreased substantially over the last few decades thanks to the implementation of energy recovery devices, high efficiency pumps, and improved membranes. However, to further increase the adoption of the technology, its energy needs must still be reduced. Batch and semi-batch reverse osmosis configurations have shown potential to be the most energy efficient reverse osmosis variants, but have remaining inefficiencies from brine mixing and high downtime. In this study, we modeled in new detail a further improved double-acting batch reverse osmosis system that uses a high-pressure tank with a reciprocating piston. A high-pressure pump is …