Thermal modeling and experimental evaluation of five different photovoltaic modules integrated on prototype test cells with and without water flow

An analytical model of temperature dependent electrical and thermal efficiency of mono-crystalline (m-Si), polycrystalline (p-Si), amorphous silicon thin film (a-Si), cadmium telluride thin film (CdTe) and copper indium gallium selenide (CIGS) photovoltaic modules integrated on five prototypes identical insulted test cells is developed with and without surface water flow. This model helps in ascertaining the influence of temperature on their performance of building integrated photovoltaic-thermal (BiPVT) system. The theoretically calculated results are experimentally validated in outdoor ambient environment. The electrical & thermal efficiencies are calculated for both high and low mass flow rate of water, ṁw. Daily average electrical efficiency of photovoltaic modules; m-Si, p-Si, a-Si, CdTe and CIGS with and without water flow are found to be 12.30%, 10.98%, 6.08%, 6.60% and 7.71%, and 11.41%, 10.30%, 5.86%, 6.26% and 6.99% respectively. In constant room temperature mode, variation in mass flow rate of water, ṁw is also evaluated. Overall thermal efficiency and overall exergy for all photovoltaic modules in both cases are also calculated. The characteristic equations of photovoltaic modules integrated on test cells are also developed for both cases

FLUENT simulations of the Westinghouse Multi-Annular Swirl Burner for design optimization

The FLUENT computational fluid dynamics code is being used to aid the design of the Westinghouse Multi-Annular Swirl Burner (MASB). The MASB is being designed by Westinghouse for use as a topping combustor in a Pressurized Fluidized-Bed Combustion System as part of the U.S. Department of Energy`s Clean Coal Technology Program. The MASB will primarily burn low-energy, coal-derived gaseous fuel (syngas) with vitiated air, at elevated pressure, to supply a gas turbine for power generation. MASB operation will require dual fuel capability, i.e., the ability to burn a high heating value fuel as well as the lower energy syngas. Firing a high heating value gas, such as methane or propane, is required during plant start-up and other off-design conditions. The goal of the current study was to devise a method for introducing dilution air into the MASB to produce an optimum pattern factor without significantly changing the existing design. This design modification must not adversely affect MASB performance when firing syngas

A reduced mechanism for low-heating-value gas combustion in a perfectly stirred reactor

We have begun an effort to accurately model NO{sub x} formation from the combustion of coal-derived fuels in turbine combustors. Both turbulent mixing and the chemical kinetics of ammonia oxidation are expected to have important influences upon NO{sub x} formation rates. This paper concentrates upon the development of a model for the kinetics. Previous empirical, kinetic mechanisms have inaccurately assumed equilibrium OH concentrations and ignored the chemistry of HCN, an important intermediate. We have developed a reduced mechanism by applying simplifying assumptions to a full, detailed mechanism for methane combustion with nitrogen chemistry. The mechanism contains 7 rates for 10 non-steady-state species, a single partial equilibrium assumption, and steady-state relations for 18 species. The Zeldovich and Fenimore mechanisms of NO formation are modeled, as is the NO recycle mechanism by which NO is converted to HCN. Nitric oxide formation from N{sub 2}O is also included. Two oxidation routes for NH{sub 3} are included: the first describes NH{sub 3} conversion to N, and then to NO; the second describes HNO formation, and final conversion of HNO to NO. Stirred reactor calculations were performed for three cases: (1) methane-air combustion with no nitrogenated species in the reactants, (2) methane-air combustion with 1000 ppmV NO in the reactants, and (3) methane-air combustion with 1000 ppmV NH{sub 3} in the reactants. The reactor temperature (1300 to 2000 K) and residence time (10{sup -4} to 10 {sup -1} s) were varied. Both the reduced and skeletal mechanism calculations agree very well with calculations using the detailed mechanism of Miller and Bowman, except for fuel-rich combustion at low temperatures (less than 1500 K), where results from the skeletal mechanism begin to deviate due to neglect of C{sub 2} chemistry

Low Emissions Combustor Test and Research Facility

The Morgantown Energy Technology Center (METC) recently built and began operation of a Low Emissions Combustor Test and Research (LECTR) facility with the primary objective of providing test facilities and engineering support to METC customers through programs such as the Advanced Turbine Systems (ATS) University-Industry Consortium and through CRADA participation with industrial partners. The LECTR is a versatile test facility with capabilities for evaluating a variety of low emissions combustion concepts at temperatures and pressures representative of gas turbine applications. The LECTR design incorporates a set of flanged sections or modules including an inlet plelnum, combustor test sections, a gas sampling section, and a quench section. The high pressure and mass flow capabilities of the LECTR facility make it uniquely suited for evaluation of advanced combustion concepts at combustion scales up to 3 MW (10 MMBtu/h)

CXCR5(+)CD8(+) T cells shape antibody responses In Vivo following protein immunisation and peripheral viral infection

Crosstalk between T and B cells is crucial for generating high-affinity, class-switched antibody responses. The roles of CD4+ T cells in this process have been wellcharacterised. In contrast, regulation of antibody responses by CD8+ T cells is significantly less defined. CD8+ T cells are principally recognised for eliciting cytotoxic responses in peripheral tissues and forming protective memory. However, recent findings have identified a novel population of effector CD8+ T cells that co-opt a differentiation program characteristic of CD4+ T follicular helper (Tfh) cells, upregulate the chemokine receptor CXCR5 and localise to B cell follicles. While it has been shown that CXCR5+CD8+ T cells mediate the removal of viral reservoirs in the context of follicular-trophic viral infections and maintain the response to chronic insults by virtue of progenitor/stem-like properties, it is not known if CXCR5+CD8+ T cells arise during acute peripheral challenges in the absence of follicular infection and whether they influence B cell responses in vivo in these settings. Using the ovalbumin-specific T cell receptor transgenic (OT-I) system in an adoptive transfer-immunisation/infection model, this study demonstrates that CXCR5+CD8+ T cells arise in response to protein immunisation and peripheral viral infection, displaying a follicular-homing phenotype, expression of cell surface molecules associated with Tfh cells and limited cytotoxic potential. Furthermore, studies assessing the B cell response in the presence of OT-I or Cxcr5-/- OT-I cells revealed that CXCR5+CD8+ T cells shape the antibody response to protein immunisation and peripheral viral infection, promoting class switching to IgG2c in responding B cells. Overall, the results highlight a novel contribution of CD8+ T cells to antibody responses, expanding the functionality of the adaptive immune system.Timona S. Tyllis, Kevin A. Fenix, Todd S. Norton, Ervin E. Kara, Duncan R. McKenzie, Shannon C. Davi

Neo-Newtonian cosmology: An intermediate step towards General Relativity

Cosmology is a field of physics in which the use of General Relativity theory is indispensable. However, a cosmology based on Newtonian gravity theory for gravity is possible in certain circumstances. The applicability of Newtonian theory can be substantially extended if it is modified in such way that pressure has a more active role as source of the gravitational field. This was done in the neo-Newtonian cosmology. The limitation on the construction of a Newtonian cosmology, and the need for a relativistic theory in cosmology are reviewed. The neo-Newtonian proposal is presented, and its consequences for cosmology are discussed.Comment: 10 pages. Portuguese version submitted to RBE

Modeling the Subsurface Structure of Sunspots

While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local helioseismology is the only means by which we can investigate subphotospheric structure. However, as current linear inversion techniques do not yet allow helioseismology to probe the internal structure with sufficient confidence to distinguish between the monolith and cluster models, the development of physically realistic sunspot models are a priority for helioseismologists. This is because they are not only important indicators of the variety of physical effects that may influence helioseismic inferences in active regions, but they also enable detailed assessments of the validity of helioseismic interpretations through numerical forward modeling. In this paper, we provide a critical review of the existing sunspot models and an overview of numerical methods employed to model wave propagation through model sunspots. We then carry out an helioseismic analysis of the sunspot in Active Region 9787 and address the serious inconsistencies uncovered by \citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find that this sunspot is most probably associated with a shallow, positive wave-speed perturbation (unlike the traditional two-layer model) and that travel-time measurements are consistent with a horizontal outflow in the surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic

CRADA opportunities in pressurized combustion research

The Morgantown Energy Technology Center recently began operation of a Low Emissions Combustor Test and Research (LECTR) Facility. This facility was built to support the development of Advanced Gas Turbine Systems (ATS) by providing test facilities and engineering support to METC customers through the ATS University-Industry Consortiu and through CRADA participation with industrial partners. The LECTR is a versatile test facility with capabilities for evaluating a variety of low emissions combustion concepts at temperatures and pressures representative of gas turbine applications. The LECTR was constructed as a mid-scale test platform to support DOE`s ATS program and utilizes the full range of high pressure (up to 30 atm) high temperature (1000{degrees}F air preheat, 3300{degrees}F combustor wall), and mass flows (3.5 lb/s combustion air) available in METC`s Advanced Combustion Facility. The LECTR is now operational and has most recently been employed to characterize the operating and emissions characteristics of an industrical-scale, lean premixed gas burner at elevated pressures for potential gas turbine applications