Experimental Investigation on the Microbial Inactivation of Domestic Well Drinking Water using Ozone under Different Treatment Conditions

The effect of ozonation on the microbial activities of domestic well drinking water was investigated, and the influence of the treatment conditions such as pH, temperature, ozone dose, and contact time was elucidated by comparing removal efficiencies. The results revealed that the disinfection of the microorganisms was related to an increase in contact time and thereby increases in Ct values with ozone. Higher ozone doses led to a large amount of microbial inactivation. The addition of hydroxyl and hydronium ions contributed greatly to the destruction of any microorganism in both acidic and basic mediums, achieving 25–88% efficiencies.     

Performance comparison of three trigeneration systems using organic rankine cycles

In this paper, energetic performance comparison of three trigeneration systems is presented. The systems considered are SOFC-trigeneration, biomass-trigeneration, and solar-trigeneration systems. This study compares the performance of the systems considered when there is only electrical power and the efficiency improvement of these systems when there is trigeneration. Different key output parameters are examined: energy efficiency, net electrical power, electrical to heating and cooling ratios, and (GHG) GHG (greenhouse gas) emissions. This study shows that the SOFC-trigeneration system has the highest electrical efficiency among the three systems. Alternatively, when trigeneration is used, the efficiencies of all three systems considered increase considerably. The maximum trigeneration efficiency of the SOFC-trigeneration system is around 76% while it is around 90% for the biomass-trigeneration system. On the other hand, the maximum trigeneration efficiencies of the solar-trigeneration system is around 90% for the solar mode, 45% for storage and storage mode, and 41% for the storage mode. In addition, this study shows that the emissions of CO₂ in kg per MWh of electrical power are high for the biomass-trigeneration and SOFC-trigeneration systems. However, by considering the emissions per MWh of trigeneration, their values drop to less than one fourth.     

Performance evaluation of different configurations of biogas-fuelled SOFC micro-CHP systems for residential applications

Three configurations of solid oxide fuel cell (SOFC) micro-combined heat and power (micro-CHP) systems are studied with a particular emphasis on the application for single-family detached dwellings. Biogas is considered to be the primary fuel for the systems studied. In each system, a different method is used for processing the biogas fuel to prevent carbon deposition over the anode of the cells used in the SOFC stack. The anode exit gas recirculation, steam reforming, and partial oxidation are the methods employed in systems I–III, respectively. The results predicted through computer simulation of these systems confirm that the net AC electrical efficiency of around 42.4%, 41.7% and 33.9% are attainable for systems I–III, respectively. Depending on the size, location and building type and design, all the systems studied are suitable to provide the domestic hot water and electric power demands for residential dwellings. The effect of the cell operating voltage at different fuel utilization ratios on the number of cells required for the SOFC stack to generate around 1 kW net AC electric power, the thermal-to-electric ratio (TER), the net AC electrical and CHP efficiencies, the biogas fuel consumption, and the excess air required for controlling the SOFC stack temperature is also studied through a detailed sensitivity analysis. The results point out that the cell design voltage is higher than the cell voltage at which the minimum number of cells is obtained for the SOFC stack.     

A comprehensive 1D model of a flowing electrolyte‐direct methanol fuel cell with experimental validation

This paper presents the development of a new comprehensive single‐phase model for a flowing electrolyte‐direct methanol fuel cell (FE‐DMFC) to determine the operating range of key input parameters for the optimum performance of the fuel cell. These parameters include the inlet concentration of the FE, as well as the flow rate and thickness of the flowing electrolyte channel (FEC). In addition, in‐house FE‐DMFC experimental results were used to validate the model for the first time. It was found that the experimental and modeling results were in a good agreement. The results of the parametric studies showed that an FE concentration within the range of 1.5 and 3.2 M would yield the best performance, while avoiding the corrosive nature of the liquid electrolyte. Furthermore, an FEC flow rate of 1 mL min^?1, at an FEC channel thickness of 0.6 mm, was deemed to be sufficiently high to remove adequate amounts of methanol from the crossover stream. It was also determined that the thinnest possible FEC thickness should be used to provide high power output. Copyright © 2014 John Wiley & Sons, Ltd.     

FRACTURE OF THICK-WALLED CYLINDERS SUBJECTED TO TRANSIENT THERMAL STRESSES

In this paper, the fracture problem of a thick cylinder subjected to transient thermal stresses is considered. The problem has practical significance in the conventional and nuclear power industries where the structural integrity of components may be damaged due to sudden temperature changes. Neglecting the inertia effects, the thermal fracture problem is uncoupled. First the thermal stresses in a thick cylinder due to a sudden change in temperature are computed separately as a function of time. Then, these stresses are used as external loads in analyzing the fracture of a thick cylinder. The assumed crack, may be an inner edge crack, outer edge crack or an embedded crack. Extensive results are obtained by varying the parameters of the problems. The main parameters affecting fracture are identified and the results are discussed in some detail.     

CFD SIMULATION OF THE GAS-SOLID FLOW IN THE RISER OF A CIRCULATING FLUIDIZED BED WITH SECONDARY AIR INJECTION

A comprehensive investigation was carried out to study hydrodynamics aspects of secondary air injection in circulating fluidized beds. This article presents modeling and results of computational fluid dynamics simulations of gas-solid flow in the riser section of a laboratory-scale (ID = 0.23 m, height = 7.6 m) circulating fluidized bed with a radial secondary air injector. The gas-solid flow model is based on the two-fluid (Eulerian-Eulerian) approach, where both gas and solids phases are treated as interpenetrating continua. A granular kinetic theory model is used to describe the solids phase stresses. The simulation results are compared with measured pressure drop and axial particle velocity profiles; reasonable agreement is obtained. Qualitatively, excellent agreement is obtained in predicting the increase in solids volume fraction below secondary air ports, the accumulation of solids around the center of the riser due to momentum of secondary air jets, and the absence of the solids down-flow near the wall above the secondary air injection ports, which are the prominent features of secondary air injection observed in the experiments.     

Analysis of bent crack in unidirectional fibre reinforced composites

This paper presents a fracture analysis for a bent crack in an infinite orthotropic plate subjected to a far-field uniform tensile stress. To determine parameters relevant to the mixed-mode fracture conditions at the tip of the bent crack, the problem is formulated in terms of singular integral equations with generalized Cauchy kernels. The resulting system of equations is then solved numberically employing a Gaussian quadrature and the collocation method. Stress intensity factors, k1 and k2, and the strain energy release rates, GI and GII at the tip of the bent crack are obtained for various values of fibres direction and L2/L1 ratios. Extensive results for a graphite-epoxy unidirectional composite laminate are presented.     

Guest Editorial Management of Mobility in Distributed Systems

Mobile Networks and Applications -