Development and validation of a three-dimensional, twophase, dual porosity, fully implicit, compositional coalbed simulator are presented. Multicomponent sorption equilibria using a thermodynamically consistent ideal adsorbed solution (IAS) theory is implemented to the simulator using a non-equilibrium sorption formulation. The sorption model accounts for the nonideality of the free gas phase, as partial fugacity of the gas component is calculated using the Peng-Robinson equation of state. Model predictions of multicomponent sorption of methane, nitrogen and carbon dioxide mixtures on the coal are found to be in good agreement with experimental measurements. The transport component of the compositional coalbed simulator is verified using an existing two-phase coalbed simulator. Introduction Enhanced coalbed methane recovery by means of injecting other gases into coalbed reservoirs is an attractive recovery technique. Reznik et al.(1) reported their experimental results of carbon dioxide injection in coal seams that can yield close to 100% methane recovery. Similar work performed by Puri and Yee(2) showed that almost all methane adsorbed to coal can be stripped by nitrogen. Modelling of carbon dioxide and nitrogen injection in enhanced coalbed methane recovery processes cannot be accurately achieved using conventional two-phase fluid flow formulations. The complex physico-chemical processes encountered require multicomponent gas sorption formulation to be coupled with compositional fluid flow formulation in coalbed reservoirs. Seidle and Arri(3) proposed a procedure to adapt conventional black oil reservoir models for coalbed methane simulation purposes. In their approach, adsorbed gas is modelled by gas dissolved in immobile oil where adsorption capacity in the physical coalbed is replaced by the solution gas-oil ratio in a black oil model. For a multicomponent gas system, they suggested to use Langmuir sorption constants and molar solution gas-oil ratio to calculate oil-gas equilibrium ratios (K-values). These K-values, together with the free gas concentration, are then used to calculate the adsorbed gas phase mole fraction and the adsorption capacity. Implementing this technique to conventional simulators with a K(p) approach, one can model compositional fluid flow in coalbed methane reservoirs without changing the original computer codes. This technique, however, requires alterations to the porosity, saturations, relative permeabilities and oil phase PVT properties data. Stevenson et al.(4) examined the validity of the thermodynamically consistent IAS and real adsorbed solution (RAS) theories in the prediction of multicomponent sorption at in-seam conditions. Later, Stevenson et al.(5) implemented this multicomponent sorption to their compositional, two-phase coalbed reservoir simulator and performed an economic evaluation and analysis of nitrogen injection for coalseam gas recovery. In these two works, information on the mathematical description of the compositional fluid flow formulation and an explanation on how to implement the sorption modelto the flow equation are not included. The principal objective of this paper is to describe the development of mathematical and numerical models of the simultaneous flow of multicomponent gas and water in coalbed reservoirs. Formulations implement the thermodynamically consistent ideal adsorbed solution (IAS) theory, which can be used as a tool to study the potentials of enhanced coalbed methane recovery in field scale coalbed reservoir simulators.

Thermal energy storage can be divided in three main categories: the storage of sensible heat, latent heat, and thermochemical heat [1]. Thermochemical heat storage is divided into storage by adsorption and storage by reaction [2]. In this work, the focus lies on the thermochemical adsorptive heat storage, which follows the mechanism shown in Scheme 1, where two components A (adsorbent) and B (adsorbate) either interact physically or react chemically [3]. The interaction or reaction of the surface A and the adsorbate B to the adsorbed species AB is exothermic and therefore releases heat which can be utilized. If energy in form of heat has to be stored, the endothermic reverse process of AB to A and B is performed.All examined adsorption systems in this work follow the mechanism of physisorption only. The energy is stored through the enthalpy of adsorption, which results from attractive forces between the adsorbate and the adsorbent (plus contributions from interactions between molecules of the adsorbate). Under the assumption of an adiabatic adsorbent fixed bed, the only loss in the process is the sensible heat, which is needed to heat the adsorbent in the adsorption and desorption process. This loss is mainly effected by the isobaric heat capacity of the adsorbent. The operation of an adsorptive energy storage system is shown in Scheme 2. If energy, in this case heat, is needed, a gas stream which is saturated with the adsorbate flows through the adsorber (A). The adsorption of the adsorbate releases heat, which heats the gas stream. AbstractThe main influencing parameter on the efficiency of adsorptive thermochemical energy storage is the efficiency of the desorption process, which is influenced by the process conditions, for example, desorption time and desorption temperature, and the working pair (adsorbent-adsorbate). Due to constrained process requirements, for example, hours of sun shine and low desorption temperatures available from a flat plate solar collector (333-373 K), the only possibility to increase the efficiency is to change the working pair. The reference working pair water-zeolite 13X needs high desorption temperatures of 500 K and high heat inputs per mass adsorbent (1080 kJ kg −1 ) in the desorption process to reach the maximum efficiency of 79 % and maximum energy density of 844 kJ kg −1 . Therefore, the goal is to reach efficiencies in the same range as the maximum efficiency of water-zeolite 13X for desorption temperatures lower than 500 K with the usage of different adsorbates. Four systems of alcohol as adsorbate on activated carbon are compared with the reference working pair. The usage of alcohols on activated carbon allows for highly efficient adsorptive storage even at low desorption temperatures between 360 and 450 K. The maximum efficiency is shifted to higher desorption temperatures with increasing carbon chain length of the alcohol. At low desorption temperatures, the energy density and efficiency of methanol, ethanol, and propanol are higher than the energy density of the refer...

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Friction stir spot welding (FSSW) process is widely used in the automobile industry for a range of applications such as battery components, standard wire connectors and terminals. This manuscript addresses two grand challenges in the arena of FSSW, hitherto, unaddressed in the extant literature: (i) lap joining of thin sheets (0.3 mm thickness) of AA 5754 alloy and (ii) lap joining of more than two sheets using FSSW. To accomplish this task, a novel pinless convex shaped tool was designed to alter the stress state while gradually advancing the tool which led to achieving stress state necessary for obtaining defect free lap joints. The weld joints were inspected by optical microscopy, SEM imaging and analysed by nanoindentation tests and Vickers microindentation tests for assessment of the quality of the weld interface (WI). Process parameters of FSSW such as torque on the tool and axially applied load were used to analytically obtain the average local measure of peak normal and axial stresses as well as the coefficient of friction in the contact zone. In samples welded at low rotational speeds, strain-hardening mechanism was seen dominating in contrast to samples welded at higher rotational

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In this work, a dissimilar copper/aluminum lap joint was generated by force-controlled hybrid friction diffusion bonding setup (HFDB). During the welding process, the appearing torque, the welding force as well as the plunge depth are recorded over time. Due to the force-controlled process, tool wear and the use of different materials, the resulting data series varies significantly, which makes quality assurance according to classical methods very difficult. Therefore, a Convolutional Neural Network was developed which allows the evaluation of the recorded process data. In this study, data from sound welds as well as data from samples with weld defects were considered. In addition to the different welding qualities, deviations from the ideal conditions due to tool wear and the use of different alloys were also considered. The validity of the developed approach is determined by cross validation during the training process and different amounts of training data. With an accuracy of 88.5%, the approach of using Convolutional Neural Network has proven to be a suitable tool for monitoring the processes.

An infrared differential comparator with no dispertor bolometer served as the heat-sensitive element;sion was built at the request of the Rubber Reserve samples in the two beams were compared six times fellowship of the Mellon Institute of Industrial Reper second and the difference in absorption was research. The instrument was designed to be used corded. The sensitivity of the instrument was for the control of the purity of various streams in the great enough to permit operation even with strongly synthetic rubber industry. Good stability was ob-absorbent filters. The operation of the instrument tained without thermostatic control by means of a under plant conditions without the necessity for frefliclter system using a single source of radiation, quent optical adjustment is attributed to the rugged symmetrical optical paths, a single radiation detector construction and the method of mounting the and alternating current amplification. A thermisoptical components.