On the Local Heat Transfer Behavior or Supercritical Carbon Dioxide

A detailed study of the local heat transfer behavior of supercritical carbon dioxide (sCO2) is performed. Flows relevant to heat transfer devices, such as sCO2 heaters, recuperators, and internally cooled turbine blades are studied, with particular attention paid to data reduction methodology, and the use of appropriate reference quantities, nondimensionalizations, and correlations. Additionally, a semi-intrusive temperature measurement technique capable of obtaining highly spatially resolved temperature distributions is adapted for use in the challenging conditions of supercritical (SC) flow. SC fluids have proven difficult to study both experimentally and numerically due to dramatically changing thermodynamic and transport properties near the critical point. It is clear from the existing literature that the heat transfer processes within a SC flow vary from those of a subcritical flow, particularly near the pseudo-critical line. Poor predictions of heat transfer rates may lead to unexpected pinch-points in heat exchangers or heat transfer degradation. Existing experimental research of SC flow heat transfer has largely been limited to spatially averaged trends and/or simplified geometries. There remains a gap between the techniques used in the subcritical regime, and the needs of the supercritical fluids industries and sciences. Numerical simulations that are benchmarked against experimental sCO2 heat transfer data evaluate the ability of existing correlations to predict heat transfer in the SC regime, both away from and very near the critical point and pseudocritical line. As it is desired to harness the advantages arising from the peaks in K and Ср along this line, a study is performed assessing the applicability of a reducedorder model to this effect. Semi-intrusive temperature measurement is achieved, using proper calibration and coating, with accuracy approximating (uncalibrated) type-T thermocouple uncertainty. The benchmarked numerical simulations give good agreement with experimental HTC data, suggesting the use of commercial RANS code is suitable as a building block for the study of the physics of these flows. New, modified heat transfer correlations are obtained for sCO2 turbine blade cooling geometry. Additionally, experimental uncertainty for calculated heat transfer quantities is quantified for the first time in the near-critical region, where fluid properties see very large gradients

Numerical Study of Mixing of a Supercritical Jet in a Supercritical Environment

A numerical simulation campaign is conducted to better elucidate flow physics and modeling requirements of a supercritical (SC) nitrogen jet injected into a tank of quiescent SC nitrogen. The goals of this work are twofold: to inform the design of injectors and combustion chambers for use in the direct-fired supercritical CO2 (s-CO2) power generation cycle and cryogenic liquid propellant rockets, and to investigate the extent to which meaningful flow characterization can be achieved with computationally expedient methods, using commercial software. Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approaches are used in STAR-CCM+ versions 10.06.010 and 12.02.011. Jet disintegration is evaluated with velocity, density and temperature profiles, potential core penetration and identification of turbulent length scales. These data are compared with experimental data and evaluated against other modeling approaches. Mixing behavior is expected to mimic that of a single-phase jet, and be diffusion-driven, as there will be no droplet formation in the supercritical phase. Challenges are encountered in high computational requirements inherent to unsteady LES. Challenges are also encountered in simulation stability and convergence given large flow gradients near jet exit, large fluid property gradients near the critical point, and the small length scale of energetic flow features unique to this high-pressure thermodynamic regime. Simulation results over-predict core penetration compared to experiment and previous numerical efforts and show an overall slower transition to ambient conditions. It is shown however that commercial code can correctly synthesize the overall flow physics and trends of the single-phase gas jet behavior expected in purely supercritical turbulent mixing flow

The Prometheus Bomb

During World War II, the lives of millions of Americans lay precariously in the hands of a few brilliant scientists who raced to develop the first weapon of mass destruction. Elected officials gave the scientists free rein in the Manhattan Project without understanding the complexities and dangers involved in splitting the atom. The Manhattan Project was the first example of a new type of choice for congressmen, presidents, and other government officials: life and death on a national scale. From that moment, our government began fashioning public policy for issues of scientific development, discoveries, and inventions that could secure or threaten our existence and our future. But those same men and women had no training in such fields, did not understand the ramifications of the research, and relied on incomplete information to form potentially life-changing decisions. Through the story of the Manhattan Project, Neil J. Sullivan asks by what criteria the people in charge at the time made such critical decisions. He also ponders how similar judgments are reached today with similar incomprehension from those at the top as our society dives down the potential rabbit hole of bioengineering, nanotechnology, and scientific developments yet to come

Christine Hartman Sullivan and Russell Neil Sullivan in a Joint Senior Recital

This is the program for the joint senior recital of clarinetist Christine Hartman Sullivan and baritone Russell Neil Sullivan. Pianist Jamie Coffelt assisted Sullivan; pianist Faron Wilson assisted Sullivan. The recital took place on March 1, 1988, in the Mabee Fine Arts Recital Hall

The Prometheus Bomb

During World War II, the lives of millions of Americans lay precariously in the hands of a few brilliant scientists who raced to develop the first weapon of mass destruction. Elected officials gave the scientists free rein in the Manhattan Project without understanding the complexities and dangers involved in splitting the atom. The Manhattan Project was the first example of a new type of choice for congressmen, presidents, and other government officials: life and death on a national scale. From that moment, our government began fashioning public policy for issues of scientific development, discoveries, and inventions that could secure or threaten our existence and our future. But those same men and women had no training in such fields, did not understand the ramifications of the research, and relied on incomplete information to form potentially life-changing decisions. Through the story of the Manhattan Project, Neil J. Sullivan asks by what criteria the people in charge at the time made such critical decisions. He also ponders how similar judgments are reached today with similar incomprehension from those at the top as our society dives down the potential rabbit hole of bioengineering, nanotechnology, and scientific developments yet to come

IMPACT OF MEAT IMPORTS ON LEAST-COST UNITED STATES BEEF PRODUCTION

International Relations/Trade,

Reaching for the Cap and Gown: Progress Toward Success Boston's College Completion Goals for Graduates of the Boston Public Schools

A new report, prepared for Mayor Martin J. Walsh and the Success Boston college completion initiative, shows a remarkable increase in both the percentage and the number of Boston Public Schools graduates who complete college within six years. The report also examines college completion for students with Success Boston coaches, a major intervention launched by the Boston Foundation and its partners, including the Boston Public Schools, in 2009. Success Boston, a citywide multi-sector college completion initiative, was launched in 2008 in response to a report that found that only 35% of the BPS Class of 2000 graduates who enrolled in college earned a degree within seven years of graduating high school. The initiative is guided by the Boston Public Schools, the Boston Foundation, UMass Boston, Bunker Hill Community College, and the Boston Private Industry Council, along with dozens of colleges, universities, and nonprofit organizations. Among the initiative's ambitious goals was pushing members of the BPS Class of 2009 to a 52%six-year college completion rate. Today's report, "Reaching for the Cap and Gown: Progress Toward Success Boston's College Completion Goals for Graduates of the Boston Public Schools," finds that the six-year college completion rate of first-year college enrollees from the BPS Class of 2009 was 51.3%--within one percentage point of the 52% goal set in 2008. Equally impressive is the gain in the number of BPS graduates completing college within six years of high school graduation--1,314 from the Class of 2009, compared to 735 from the Class of 2000, the equivalent of a 79% increase. The study also finds that college completion, at 54.7%, is even higher than the goal for students who enrolled in the fall immediately after graduating from high school

Leukemia and Retroviral Disease

Two human retroviruses, identified as the human T-cell leukemia virus type 1 (HTLV-1) and human immunodeficiency virus type 1 (HIV-1), have been shown to affect millions of people worldwide. In the context of coinfection, the impact of their interactions with respect to HTLV-1-induced adult T-cell leukemia and neurologic disease as well as HIV-1 disease progression has been an understudied area of investigation. HTLV-1/HIV-1 coinfections occur frequently, particularly in large metropolitan areas of the Americas, Africa, Europe, and Japan. The retroviruses HTLV-1 and HIV-1 share some similarities with regard to their genetic structure, general mechanisms of replication, modes of transmission, and cellular tropism; however, there are also significant differences in the details of these properties as well, and they also differ significantly with respect to the etiology of their pathogenic and disease outcomes. Both viruses impair the host immune system with HIV-1 demonstrated to cause the hallmark lethal disease known as the acquired immune deficiency syndrome (AIDS), while HTLV-1 infection has been shown to cause several different forms of T-cell leukemia. In addition, both viruses have also been shown to cause a spectrum of neurologic disorders with HIV-1 shown to cause an array of neurologic syndromes referred to as HIV-1-associated neurologic disorders or HAND, while HTLV-1 has been shown to be the etiologic agent of HTLV-1-associated myelopathy/tropical spastic paraparesis or HAM/TSP. The natural history of the coinfection, however, is different from that observed in monoinfections. Several studies have demonstrated utilizing a number of in vitro models of HTLV-1/HIV-1 coinfection that the two viruses interact in a manner that results in enhanced expression of both viral genomes. Nevertheless, there remains unresolved controversy regarding the overall impact of each virus on progression of disease caused by both viruses during the course of coinfection. Although combination antiretroviral therapy has been shown to work very effectively with respect to maintaining HIV-1 viral loads in the undetectable range, these therapeutic strategies exhibit no benefit for HTLV-1-infected individuals, unless administered immediately after exposure. Furthermore, the treatment options for HTLV-1/HIV-1-coinfected patients are very limited. In recent years, allogeneic stem cell transplantation (alloSCT) has been used for the treatment of leukemia. In this regard, the case of a leukemic patient positive for HIV-1 who was cured of their HIV-1 infection while treated with alloSCT for acute myeloid leukemia has also been examined with regard to impact on HIV-1 disease