There has been serious interest in hydrogen as a source of energy in the United States due to its capability of delivering a sustainable, carbon-free energy future. Currently, most hydrogen in the United States is produced via the steam methane reforming of natural gas, which converts methane to hydrogen through...
Waste-heat-recovery Organic Rankine Cycle (ORC) systems use excess heat from industrial processes to produce electrical power. In many cases, the temperatures and mass flow rates of these excess-heat streams vary significantly over time, causing the ORC to often operate far from its design point. In this study, a control strategy...
This work compares the condensation heat transfer and pressure drop for zeotropic refrigerant R-454C and its individual components, R-32 and R-1234yf, in horizontal microfin tubes. One microfin tube has a 4 mm outer diameter, 0.18 mm wall thickness, and a surface area ratio of 1.56. The second tube has a...
With the continued decrease in size and subsequent increase in power of computer processors, thermal management in electronics is becoming more important than ever before. The chip heat densities are reaching new peaks (> 100 W cm-2) that current cooling methods are not able to keep up with. However, some...
This work investigates the in-tube condensation of low global warming potential (GWP) zeotropic refrigerant mixtures R448A, R450A, R452A, R454B and R454C. These refrigerants have been proposed for a wide range of commercial heating, ventilation, air-conditioning applications, but their heat and momentum transport phenomenon were not well understood. Thus, in this...
Seven decades of supercritical heat transfer research have not seen an attempt to characterize turbulent thermal transport in internal flows subject to asymmetric heating. Existing heat transfer models therefore do not account for phenomena that dictates thermal transport, in the proximity of the pseudo-critical point, for non-uniform heating. Additionally, past...
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...
Membrane based heat pumps systems have attracted the attention of many research groups as a potentially more environmentally friendly alternative to vapor compression systems that are being used for space cooling in 90\% of the buildings in the United States. Several prototypes systems have been developed, with reported claims of...
A significant source of energy consumption comes from maintaining desired indoor environment conditions in warehouses and other industrial facilities. In efforts to combat the raising energy costs, studies into more efficient heating and cooling strategies has been a topic of consideration for a number of years. One of the areas...