Numerical study of on-board fuel reforming in a catalytic plate reactor for solid-oxide fuel cells

A pseudo-transient numerical model is used for the simulation of a multi-functional catalytic plate reactor (CPR). The work mainly addresses the problems associated with on-board reforming for solid-oxide fuel cells. Heat management is achieved by indirectly coupling partial oxidation with reforming. Water management is achieved by partially recycling the anode stream from a solid-oxide fuel cell. The model uses detailed heterogeneous chemistry for reforming and oxidation reactions occurring on the catalyst beds

Micro-kinetic modeling of NH3 decomposition on Ni and its application to solid oxide fuel cells

This paper presents a detailed surface reaction mechanism for the decomposition of NH3 to H2 and N2 on a Ni surface. The mechanism is validated for temperatures ranging from 700 to 1500K and pressures from 5.3Pa to 100kPa. The activation energies for various elementary steps are calculated using the unity bond index-quadratic exponential potential (UBI-QEP) method. Sensitivity analysis is carried out to study the influence of various kinetic parameters on reaction rates. The NH3 decomposition mechanism is used to simulate SOFC button cell operating on NH3 fuel

A detailed kinetic model for biogas steam reforming on Ni and catalyst deactivation due to sulfur poisoning

This paper deals with the development and validation of a detailed kinetic model for steam reforming of biogas with and without H2S. The model has 68 reactions among 8 gasphase species and 18 surface adsorbed species including the catalytic surface. The activation energies for various reactions are calculated based on unity bond index-quadratic exponential potential (UBI-QEP) method. The whole mechanism is made thermodynamically consistent by using a previously published algorithm. Sensitivity analysis is carried out to understand the influence of reaction parameters on surface coverage of sulfur. The parameters describing sticking and desorption reactions of H2S are the most sensitive ones for the formation of adsorbed sulfur. The mechanism is validated in the temperature range of 873-1200 K for biogas free from H 2S and 973-1173 K for biogas containing 20-108 ppm H2S. The model predicts that during the initial stages of poisoning sulfur coverages are high near the reactor inlet; however, as the reaction proceeds further sulfur coverages increase towards the reactor exit. In the absence of sulfur, CO and elemental hydrogen are the dominant surface adsorbed species. High temperature operation can significantly mitigate sulfur adsorption and hence the saturation sulfur coverages are lower compared to low temperature operation. Low temperature operation can lead to full deactivation of the catalyst. The model predicts saturation coverages that are comparable to experimental observatio

Predicting the temperature and reactant concentration profiles of reacting flow in the partial oxidation of hot coke oven gas using detailed chemistry and a one-dimensional flow model

A numerical approach is presented for predicting the species concentrations and temperature profiles of chemically reacting flow in the non-catalytic partial oxidation of hot coke oven gas (HCOG) in a pilot-scale reformer installed on an operating coke oven. A detailed chemical kinetic model consisting of 2216 reactions with 257 species ranging in size from the hydrogen radical to coronene was used to predict the chemistries of HCOG reforming and was coupled with a plug model and one-dimensional (1D) flow with axial diffusion model. The HCOG was a multi-component gas mixture derived from coal dry distillation, and was approximated with more than 40 compounds: H2, CO, CO2, CH4, C2 hydrocarbons, H2O, aromatic hydrocarbons such as benzene and toluene, and polycyclic aromatic hydrocarbons up to coronene. The measured gas temperature profiles were reproduced successfully by solving the energy balance equation accounting for the heat change induced by chemical reactions and heat losses to the surroundings. The approach was evaluated critically by comparing the computed results with experimental data for exit products such as H2, CO, CO2, and CH4, in addition to the total exit gas flow rate. The axial diffusion model slightly improves the predictions of H2, CO, and CO2, but significantly improves those of CH4 and total exit flow rate. The improvements in the model predictions were due primarily to the improved temperature predictions by accounting for axial diffusion in the flow model

A Viable Approach for Measuring the Risk-Return Relationship of IT Investments

The importance of managing the risk-return balance of information technology (IT) investments has become clearer than ever. Yet, quantitative assessment of IT investment risk and return based on financial measures remains a major challenge. Recently scholars have used event study analysis to measure the value created via IT investment, by examining the abnormal changes in shareholder wealth around the time a specific IT investment is announced. The abnormal return on equity due to such an event is considered a good proxy for the economic value of that event. In the same spirit, this research proposes estimating several forms of IT investment risk, by combining event study analysis with the use of arbitrage pricing theory. In so doing, this research contributes towards the development of an integrated approach for quantifying the risk-return relationship for IT investment so that practitioners can make more informed investment decisions

TALENT RETENTION IN PRIVATE ENGINEERING INSTITUTIONS IN RURAL PARTS OF ANDHRA PRADESH, INDIA

It has been observed that, Talent Retention in Higher Educational Institutions is an ongoing problem in rural parts of India and Andhra Pradesh is no exception to this phenomenon. Many private higher educational institutions especially Engineering Educational Institutions in rural Andhra Pradesh are on the wedge of closure and are not in a position to sustain due to lack of revenue generation to meet even the operational expenses and with this, the existing huge and expensive infrastructure of these sick institutions are going to turn in to National Waste. This has been the burning problem for the last six to seven years due to little importance given to the most important aspect, “Talent Retention”. It is strongly believed that, institutions are made up of staff both Teaching and Non-Teaching: Teaching Staff creating value through proven teaching & Learning processes, innovation, mentorship and many other relevant activities and Non-Teaching staff providing administrative and logistic support to fulfill the needs of the deliverables of Teaching staff. As, an Educational institution strives to meet its organizational goals, it must make sure that it has a continuous and integrated process for Recruiting, Training, Managing, Supporting and Compensating these people to achieve high success rate of Talent Retention

Androgen Receptor Function Links Human Sexual Dimorphism to DNA Methylation

Sex differences are well known to be determinants of development, health and disease. Epigenetic mechanisms are also known to differ between men and women through X-inactivation in females. We hypothesized that epigenetic sex differences may also result from sex hormone functions, in particular from long-lasting androgen programming. We aimed at investigating whether inactivation of the androgen receptor, the key regulator of normal male sex development, is associated with differences of the patterns of DNA methylation marks in genital tissues. To this end, we performed large scale array-based analysis of gene methylation profiles on genomic DNA from labioscrotal skin fibroblasts of 8 males and 26 individuals with androgen insensitivity syndrome (AIS) due to inactivating androgen receptor gene mutations. By this approach we identified differential methylation of 167 CpG loci representing 162 unique human genes. These were significantly enriched for androgen target genes and low CpG content promoter genes. Additional 75 genes showed a significant increase of heterogeneity of methylation in AIS compared to a high homogeneity in normal male controls. Our data show that normal and aber

Pricing e-service quality risk in financial services

a b s t r a c t E-service quality is crucial for differentiating e-commerce offers and gaining competitive advantage. Eservice quality risk is the risk that a firm's e-service quality will drop, or improve, relative to competitors. There is evidence that benchmark ratings of e-service quality that are published regularly by third-parties can impact the market value of rated firms. Firms therefore continue investing in IT-related determinants of e-service quality. However, they do so without knowing: (1) the cost or return associated with a unit relative deterioration, or improvement in e-service quality ratings, and (2) how this cost or return may vary across firms. To answer these questions, we adapt a well-established financial risk pricing approach for the case of pricing a single idiosyncratic IT investment risk, where an event study is used to generate the market data needed to price ris

Experimental and Theoretical Investigation of Catalyst Poisoning and Regeneration During Biogas Steam Reforming on Nickel

Biogas is an important source of renewable energy produced by the anaerobic digestion of biomass. The composition of biogas depends on the biomass source and duration of the digestion process. Biogas is an ideal fuel for distributed power generation using Solid-Oxide Fuel Cells (SOFCs), especially in areas that are not grid connected. Biogas may be combusted to produce electricity or can be converted to synthesis gas by reforming over Rh or Ni catalyst. However, the presence of H2S or other sulfur containing compounds is a major problem for reforming of biogas because sulfur poisons most transition metals. The goal of this research is two fold; i) experimental investigation of catalyst deactivation and regeneration, and ii) development of a comprehensive predictive microkinetic model for biogas steam reforming on Ni based catalysts. The kinetic model is developed based on experimental data and further validated by simulating the experiments reported in the literature. The kinetic model is able to capture the performance of a fixed bed reactor used to reform model biogas with and without H2S in the feed gas. The objective of the experimental study is the deactivation and regeneration of Ni catalysts supported on γ-Al2O3 during steam reforming of biogas containing ppm levels of H2S. In order to ensure that the catalyst does not lose activity over time in a non-poisoning atmosphere (without H2S), reforming experiments are performed at 700 and 800 ◦C for 22 hrs and no loss in activity of the catalyst is observed during this period. Catalyst deactivation experiments are then performed for two different temperatures (700 and 800 ◦C) and three different H2S concentrations (20, 50, and 100 ppm). A low S/C ratio is employed to ensure the participation of CO2 in reforming reactions. Low temperature operation (700 ◦C) lead to full deactivation of the catalyst where as at higher temperature (800 ◦C) the catalyst maintained some residual activity. In certain cases, catalyst regeneration is also performed by removing H2S from the feed gas and by increasing the reforming temperature. The fully poisoned catalysts are then regenerated by steam treatment followed by reduction in H2. The regenerated catalyst is tested for its activity by performing steam reforming reaction without H2S in the feed stream. The regenerated catalyst showed stable operation for more than 13 hrs