HDPE pipes failure analysis and damage modeling

Thermoplastic pipes are used in all the industrial fields such as water, sewage and gas piping systems and other industrial applications, like the transport of minerals and slurries. The choice of the right piping system's material depends on many criteria. First of all, it depends on the conditions of use of each kind of material. Secondly, it depends on the cost of the chosen material and finally the mastering of the material's scenarios of failure. The last criteria are possible through the mastering of the material characteristics and the capability to detect the failure, burst or crack, before its occurrence. The adopted approach must be proactive to facilitate the prediction of the failure and help the maintenance staff to apprehend the piping system's damage at the right time. In this paper, we chose HDPE pipes as material for our study. Then, we leaded a new approach of failure analysis and prediction using new models. These models are obtained through a modified version of the stress controlled unified theory, a static damage model using burst pressures and a static damage model using the time to failure. For that reason, we used burst pressures of undamaged HDPE pipe instead of ultimate stresses. Then, we created groove notches with different levels of depth. The obtained burst pressures from these pipes have been considered as the residual burst pressures used in our damage models. The representation of the obtained data according to the life fraction gave us an idea about the critical life fraction and then the critical groove depth which can be allowed. This information has been confirmed by three damage models. Then, we determined the different stages of damage to help the predictive maintenance to define the safe intervals of the HDPE pipes' service. Moreover, the three developed models, presented in this paper, represent a simplified approach to assess the damage based on static tests only, without doing any dynamic tests. The developed cost-effective approach can be a tool that can help the industrials to have an anticipative maintenance strategy and respect the safety requirements. Also, it can help them to do quick checks or launch audit mission to the manufacturers' factories for HDPE pipes' quality control and conformity check regarding the codes.     

A framework for allocating greenhouse gas emissions from electricity generation to plug-in electric vehicle charging

This paper describes a number of different allocation methods for assigning greenhouse gas emissions from electricity generation to charging plug-in electric vehicles. These methods for calculating the carbon intensity of electricity are discussed in terms of merits and drawbacks and are placed into a framework to aid in understanding the relation with other allocation methods. Three independent decisions are used to define these methods (average vs. marginal, aggregate vs. temporally-explicit, and retrospective vs. prospective). This framework is important because the use of different methods can lead to very different carbon intensities and studies or analyses that do not properly identify the methods used can confuse policymakers and stakeholders, especially when compared to other studies using different methods.     

Electrocatalytic oxidation of cyclohexanol on a nickel oxyhydroxide modified nickel electrode in alkaline solutions

Electrocatalytic oxidation of cyclohexanol was investigated with cyclic voltammograms, linear galvanic voltammograms and chronoamperometric responses on a nickel oxyhydroxide modified nickel (NOMN) electrode prepared by cycling the potential of a nickel electrode in the potential range of 0.1 V to 0.6 V (vs SCE) in alkaline solutions. It was found that cyclohexanol was oxidized by NiOOH generated with further electrochemical oxidation of nickel hydroxide during the anodic potential sweep. One of the products of the reaction between cyclohexanol and NiOOH was Ni(OH)₂ which was subsequently oxidized to NiOOH on the anode. This resulted in the appearance of a new anodic peak in cyclic voltammograms compared with the absence of cyclohexanol and this anodic peak strongly depends upon potential scan rates and cyclohexanol concentrations. In addition, the presence of cyclohexanol in NaOH solutions also lead to the decrease of anodic potentials in linear galvanic voltammetric responses and the increase of current densities in chronoamperometric curves. Results showed that the oxidation of cyclohexanol on the NOMN electrode follows the catalytic reaction mechanism.     

Analysis of transport phenomena within PEM fuel cells – An analytical solution

Transport phenomena within PEM fuel cells are investigated and a comprehensive analytical solution is presented. The methodology couples the transport within the fuel cell supply channels and the substrate which is composed of five different layers. The layers are all treated as macroscopically homogeneous porous media with uniform morphological properties such as porosity and permeability. The locally volume-averaged equations are employed to solve for transport through the porous layers. The problem encompasses complex interfacial transport phenomena involving several porous–porous as well as porous–fluid interfaces. Chemical reactions within the catalyst layers are also included. The method of matched asymptotic expansions is employed to solve for the flow field and species concentration distributions. Throughout the analysis, the choice of the gauge parameters involved in the perturbation solutions for velocity and concentration is found to be inherently tied to the physics of the problem and therefore an important physical metric. The analytical solution is found to be in excellent agreement with prior computational simulations. The analytical results are used to investigate several aspects of transport phenomena and their substantial role in PEM fuel cell operation. The solution presented in this work provides the first comprehensive analytical solution representing fuel cell transport phenomena.     

Base‐Catalyzed Depolymerization of Lignin: Separation of Monomers

In our quest for fractionating lignocellulosic biomass and valorizing specific constitutive fractions, we have developed a strategy for the separation of 12 added value monomers generated during the hydrolytic based‐catalyzed depolymerization of a Steam Exploded Aspen Lignin. The separation strategy combines liquid‐liquid‐extraction (LLE), followed by vacuum distillation, liquid chromatography (LC) and crystallization. LLE, vacuum distillation and flash LC were tested experimentally. Batch vacuum distillation produced up to 4 fractions. Process simulation confirmed that a series of 4 vacuum distillation columns could produce 5 distinct monomer streams, 3 of which require further chromatography and crystallization for purification.     

Potential benefits from improved energy efficiency of key electrical products: The case of India

The economy of the world's second most populous country continues to grow rapidly, bringing prosperity to a growing middle class while further straining an energy infrastructure already stretched beyond capacity. At the same time, efficiency policy initiatives have gained a foothold in India, and promise to grow in number over the coming years. This paper considers the maximum cost-effective potential of efficiency improvement for key energy-consuming products in the Indian context. The products considered are: household refrigerators, window air conditioners, motors and distribution transformers. Together, these products account for about 27% of delivered electricity consumption in India. The analysis estimates the minimum Life-Cycle Cost option for each product class, according to use patterns and prevailing customer marginal rates in each sector. This option represents an efficiency improvement ranging between 12% and 60%, depending on product class. If this level of efficiency was achieved starting in 2010, we estimate that total electricity consumption in India could be reduced by 4.7% by 2020, saving over 74 million tons of oil equivalent and over 246 million tons of carbon dioxide emissions. Net present financial savings of this efficiency improvement totals 8.1 billion dollars.