Implementing Power‐to‐Gas to provide green hydrogen to a bitumen upgrader

Hydrogen is an important commodity in the processing of intermediate bitumen products into a finished petroleum product and for upgrading bitumen into synthetic crude. With the continued extraction of bitumen‐rich material from Alberta's oil sands project, there is an opportunity to reduce the greenhouse gas emissions of upgrading and refining operations by using electrolytically produced hydrogen in place of hydrogen produced by steam methane reformation. Recently, a bitumen upgrading facility had been proposed for the city of Sarnia, Ontario because of its pre‐existing petroleum processing infrastructure. Using the Ontario electrical system, which has a lower emissions factor than Alberta, the use of electrolytic hydrogen could result in a significant reduction of greenhouse gasses. In this paper, the objective is to determine an optimal system configuration for reducing greenhouse gas emissions while maintaining a low system cost. The analysis is performed with General Algebraic Modelling System tool, a mixed‐integer linear optimization in addition to a simple model in Visual Basic. For each case, an economic and environmental analysis is performed including the use of cap‐and‐trade values for the price of carbon emissions, which are applied to determine the overall economic impact of the emissions reductions. Copyright © 2016 John Wiley & Sons, Ltd.     

Response to “Commentary by Dr. Henryk Drulis”

One safety aspect of a material-based hydrogen storage system is the exposure of such system to a high-temperature environment (e.g., a fire) causing an increase in pressure. A simple analysis, based on a material balance, is provided to estimate the effect of temperature on equilibrium storage pressure in a material-based hydrogen storage system. Jiann C. Yang in Int J Hydrogen Energy 33 (2008) 4424–4426.     

Fitting the duct to the “body” of the convective flow

This paper is a proposal to design flow structures with maximal heat transfer rate per unit volume, by shaping each duct so that it fits optimally on the body of the convective flow. Optimally shaped ducts can be assembled into larger constructs. Two examples are given. In the first, a heat-generating strip is cooled inside a duct of rectangular cross-section. The duct geometry has two degrees of freedom, which can be selected so that the fixed duct volume packs a maximum of heat transfer rate. In the second example, the duct is a tube with isothermal internal surface, and the flow is sufficiently slow so that boundary layers do not form inside the duct. Once again, the duct aspect ratio can be optimized for maximal heat transfer rate density. Further improvements can be sought by endowing the duct geometry with more degrees of freedom.     

The k‐ϵ‐fP model applied to wind farms

The recently developed k‐?‐f_P eddy‐viscosity model is applied to one on‐shore and two off‐shore wind farms. The results are compared with power measurements and results of the standard k‐? eddy‐viscosity model. In addition, the wind direction uncertainty of the measurements is used to correct the model results with a Gaussian filter. The standard k‐? eddy‐viscosity model underpredicts the power deficit of the first downstream wind turbines, whereas the k‐?‐f_P eddy‐viscosity model shows a good agreement with the measurements. However, the difference in the power deficit predicted by the turbulence models becomes smaller for wind turbines that are located further downstream. Moreover, the difference between the capability of the turbulence models to estimate the wind farm efficiency reduces with increasing wind farm size and wind turbine spacing. Copyright © 2014 John Wiley & Sons, Ltd.     

淀粉样心肌病的诊断

【摘要】 目的 探讨淀粉样心肌病的诊断方法。方法 分析2例表现为难治性右心衰竭患者，分别采用右心导管和心内膜活检等方法明确诊断。结果 2例患者心脏超声和MRI均提示室间隔增厚、心肌回声和延迟扫描增强，右心导管检查提示右心压力增高，心内膜活检刚果红染色阳性。结论 心脏症状通常是系统性淀粉样变性的第一表现，部分患者表现为难治性心力衰竭，右心导管和心内膜活检可以明确诊断。
     

Ammonia borane at low temperature down to 90 K and high pressure up to 15 GPa

We have studied the phase transformation behavior of the potential hydrogen storage compound ammonia borane at low temperature (from room temperature down to 90 K) and high pressure (from ambient pressure to 9.5 GPa at room temperature and up to 15 GPa at 90 K) region using the diamond anvil cell. This material shows four new phase transitions in this pressure and temperature region. The phase transition phenomenon is evidenced by the splitting of the peak and/or the appearance of the new peak in the Raman spectra as well as by the change of the pressure coefficient of the Raman modes. The phase boundaries between these phases are also established from the data collected during different cooling cycles. These results provide the information about the stability of the bonding characteristics of this potential hydrogen storage material at low temperature and high pressure region.     

The nonlinear response of inverted “V” flames to equivalence ratio nonuniformities

Recent studies indicate that heat release fluctuations generated by equivalence ratio perturbations may constitute sources of instability with effects similar to those induced by acoustic perturbations. The present article addresses this issue by considering the dynamics of an inverted laminar dihedral (“V”) flame spreading in an open geometry when this flame is submitted to equivalence ratio modulations. The problem is investigated with numerical simulations by first establishing a steady state flame which then evolves in a uniform flow transporting a fixed level of equivalence ratio perturbations. The flame features wrinkles of increasing amplitude locking on the convected composition perturbations. The wrinkling amplitude grows with distance from the injector. For sufficiently large wrinkle amplitudes, the flame interacts with the fresh mixture outer boundary, giving rise to sudden disruptions of the flame sheet. The rapid burning of fresh mixture pockets generates a nonlinear heat release signal with abrupt changes in the waveform. It is found that high levels of modulation induce axial velocity perturbations, which in turn interact with the flame and modify the response. Calculations described in this article may serve to guide analytical modeling of the response of combustion to equivalence ratio inhomogeneities. A simple model is devised on this basis to distinguish regimes corresponding to weak and strong interactions.     

Heat exchanger: from micro‐ to multi‐scale design optimization

This paper presents a consideration of micro‐heat exchangers design optimization for the aim of process intensification. Two examples are discussed to illustrate different ways of heat transfer intensification in micro‐heat exchangers. To solve the key issue of the link between the micro‐scale and the macro‐scale, a multi‐scale design optimization method using fractal and constructal approaches is introduced. The concept of a novel constructal heat exchanger is also proposed. Copyright © 2007 John Wiley & Sons, Ltd.