This article investigates the in-tube, superheated, saturated, and subcooled condensation of zeotropic refrigerant mixture R454C. R454C is proposed to replace R404A for commercial refrigeration applications. Quasi-local heat transfer coefficients were measured in a 4.7 mm horizontal tube at mass fluxes ranging from 100 to 500 kg m−2 s−1 at three different saturation...
In the second chapter, a foam-core meniscus coating process was developed for retrofitting 100 nm-scale sol-gel anti-reflective coatings onto in-field solar panels through the deposition, evaporation, and curing of wet films.Advantages of this technique include the means to control fluid flow relative to substrate motion and the ability to conform...
Cephalopod-inspired soft robot arms have been studied as a new type of manipulator. These arms have been proposed for reach and grab tasks, underwater locomotion via swimming and walking, and robotic surgery. However, the capabilities of existing soft arms are limited to simple motions and light loads. Arm design has...
Hydrogen is an increasingly attractive low-carbon energy carrier for a variety of stationary and mobile applications. Currently, the vast majority of hydrogen in the United States is produced via the energy intensive steam reforming of natural gas. The cost and carbon emissions associated with hydrogen production can be reduced by...
Increasing interest in hydrogen as a clean and efficient energy carrier has driven the need to improve its production and distribution methods. Of particular interest is the natural gas reforming process which currently accounts for 48% of hydrogen production in the United States. Existing natural gas delivery infrastructure and challenges...
The objective of this paper was to measure and compare the heat transfer coefficient and pressure drop of R404A and two potential replacement candidate refrigerants with a lower global warming potential, R448A and R452A. Experiments were conducted inside a 4.7 mm horizontal tube at mass fluxes ranging from 100 to...
In the event of a mid-flight flameout of a gas turbine engine, reignition is paramount to occupant safety. Ignition at high altitude can be challenging, due in part to the potentially lower ambient pressures. An understanding of the effects of sub-atmospheric pressures on the temperature evolution of spark kernels is...
Oxide dispersion strengthened (ODS) alloys exhibit superior mechanical properties due to the presence of nano-sized thermally stable oxide particles. However, manufacturing of ODS alloys is very complex and composed of numerous time consuming steps such as mechanical alloying, which is one of the main barriers toward the widespread application of...
The recyclability of 316L stainless steel powder in the binder jetting process has been determined. The powder characterization results demonstrated a 22% increase in the number of coarse particles (> 30 µm) and an 18.2% reduction in the number of small particles (< 10 µm) after recycling up to 16 times. A...
This paper discusses the fundamentals of a novel hybrid method to synthesize oxide dispersion strengthened (ODS) 304 L stainless steel (SS) alloy using a modified laser powder bed fusion (LPBF) machine. Previously, ODS metal matrix composites have been produced by LPBF via ball-milling, which is expensive to scale. Here, we selectively...