In this paper, the outflow process of a sharp-crested and broad weir is studied using the dimensional analysis and the incomplete self-similarity theory. The new stage discharge is theoretically ...deduced and its testing is carried out using measurements both available in literature and obtained by laboratory runs carried out in this investigation.
In this paper the results of the experiments performed to study the flow through a Triangular Central Baffle Flume (TCBF) are reported. The investigated flume consists of a triangular baffle of the ...apex angle of 75° with a given base width. The theoretical stage-discharge formula was deduced by applying the Buckingham's Theorem and incomplete self-similarity hypothesis and was calibrated using the laboratory measurements carried out in this investigation. The proposed stage-discharge formula is characterized by a mean absolute relative error of 7.4% and 72% of the data points are in an error range of ±5%. The results indicate that TCBF flume is characterized by a flow capacity higher than that of a typical central baffle flume. Experimental observations show that the contraction ratio is a key parameter to distinguish between free and submerged flow regimes through a TCBF. Finally, to identify the flow condition, submergence threshold condition was formulated.
•A flow measuring device called as Triangular Central Baffle Flume, TCBF, is presented in this study.•Experiments are performed to formulate the stage-discharge curve for free flow condition.•Submergence threshold curve is studied experimentally to identify the flow condition through TCBF.
The Universal Soil Loss Equation (USLE) was originally deduced by a statistical analysis of a large data set of soil loss measurements. The multiplicative structure of the model has been criticised ...due to the considerable interdependence between the variables. Using the soil erosion representative variables and the reference condition adopted in the USLE, the aim of this paper was to apply dimensional analysis and self-similarity theory to deduce the functional relationship among the selected variables. The analysis yielded a multiplicative equation, similar to the USLE. Therefore, this study suggested that the USLE has a logical structure with respect to the variables used to simulate the physical soil erosion process and the adopted reference condition.
•NH3–IL absorption cycles are modeled by COSMO-based Aspen simulations.•Proposed a priori computational approach is validated using experimental data.•Cycle performance was analyzed for conventional ...and task-specific ILs.•IL solvents with high NH3 absorption capacity improve the cycle performance.•Using IL mixtures is revealed as promising alternative in NH3 absorption applications.
COSMO-based process simulations with Aspen Plus/Aspen HYSYS are used, for the first time, to a priori estimate the thermodynamic performance of ammonia absorption refrigeration cycles using ionic liquids as absorbents. This allows not only broadening the criteria set used to select/design ionic liquids with optimized properties to be used in that role, but also evaluating innovative strategies to improve the cycle’s performances. COSMO-RS method provides the information required for both creating the ionic liquid non-database components and specifying the COSMOSAC property model to perform Aspen Plus calculations. The computational procedure used here gives at the same time reasonable good property predictions of the vapor (refrigerant) and the condensed (ammonia+ionic liquid) phases as well as physically consistent estimations of the cycle’s performance under different conditions. Current results agree with those previously reported in the literature for several ionic liquid-based systems taken for comparison. In addition, task-specific ionic liquids, with improved properties for ammonia absorption, and also binary ionic liquid mixtures are considered in the analysis. It is obtained that ionic liquids showing higher ammonia absorption capacity among the considered absorbents simultaneously provide the best cycle’s performances. The cycle performances vary in relatively wide intervals depending on the ammonia concentration in the (refrigerant+absorbent) solutions. This behavior is strongly modulated by the ammonia absorption capacity of the selected absorbent. IL mixtures allow not only the tailoring of the working concentration interval of the cycle but also improving its performance.
Rainfall is one of the factors affecting soil erosion, and rainfall kinetic energy or momentum is used to represent the capability of the precipitation to erode soil, named rainfall erosivity. ...Accurate measurements of rainfall erosivity are useful for a reliable prediction of soil loss. Rainfall momentum and kinetic energy, both calculated per unit time and area, can be obtained using terminal raindrop velocity and the drop size distribution (DSD) measured by disdrometers, which are instruments expensive and not suitable for large scale use. An innovative patented method to measure the rainfall energy is based on the estimation of DSD by simultaneous detection, in a given time interval, of the rainfall intensity I and the number N of raindrops that hit a specific piezoelectric surface. In this paper, advances of this method are presented. In particular, two new theoretical procedures to estimate the parameters μ and Λ of Ulbrich's distribution, that allow for the calculation of the rainfall kinetic energy and momentum, are proposed. Both procedures (Scenario 1 and 2) are based on the frequency distribution of the momentum M(D) of raindrops detected in a sampling time interval. Specifically, in the Scenario 1, μ and Λ are estimated by using I, N and the standard deviation, s(D), of the drop diameters obtained from the measured momentum distribution. In the Scenario 2 the parameters are estimated using I, N and the mean value, m(D), of the drop diameters deriving from the momentum distribution. The reliability of the proposed procedures was tested using DSD measurements recorded in three different experimental sites. The developed analysis demonstrated that Scenario 2 is the best method to estimate μ and Λ, and to reproduce the DSD, accordingly. The proposed method, associated with a patented device, not yet build, will allow the direct measurement of the rainfall energy characteristics, which are usually roughly estimated from rainfall intensity. The possibility to easily measure these energy variables can support the development of research in the field of soil erosion and, in general, of hydrogeological instability. In particular, the proposed measurement method and the construction of the device could stimulate the scientific community to deepen the study of the effect of the rainfall energy on soil erosion for improving the predictive capability of water erosion models.
The knowledge of rainfall intensity, the droplet number and the mean diameter obtained by rainfall momentum distribution allows to reproduce the DSD and to measure the rainfall impact by momentum, M, and kinetic power, Pn. The simple and cheap devise, already patented, could be improved by making it suitable to measure all these variables.
•SLE is properly described with refined e-NRTL electrolyte-solvent parameters.•Systems showing multiple precipitate equilibria are more difficult to predicted.
The aim of this work is to use the ...refined binary electrolyte-solvent interaction parameters of the e-NRTL model obtained in a previous paper (J.L. Valverde et al. Fluid Phase Equilibria (2022), 551, 113264) and to analyse the impact of considering the electrolyte-electrolyte interaction parameters different from zero on the prediction of solid-liquid equilibria in salt-water mixtures. For this purpose, experimental data were fitted to the complete e-NRTL model by non-linear regression. Ternary (two salts + water) and quaternary (three salts + water) systems were considered. Almost all the systems analyzed were precisely predicted by using the e-NRTL model with the electrolyte-water pairs regressed previously and electrolyte-electrolyte ones set to zero. Including the electrolyte-electrolyte binary parameters in a proper way can slightly improve the solid-liquid equilibria prediction for some of the selected systems. The Na2SO4+K2SO4+Li2SO4+H2O mixture was described poorly than the remainder ones computed due to the complexity of the system which exhibits the formation of multiple salts.
► In this paper COSMO-RS methodology is integrated to Aspen Tech’s process simulators. ► New criteria for the design/selection of ionic liquids to specific applications are elaborated. ► These ...criteria are related to the operating conditions and energetic consumptions of the processes. ► The procedure capabilities are demonstrated through the example of the IL regeneration in separation processes.
The integration of COSMO-RS methodology to Aspen Tech’s process simulators is used in this work to elaborate new criteria for the design/selection of ionic liquids to specific applications. These criteria are related to the operating conditions and energetic consumptions being the procedure capabilities demonstrated through the example of the IL regeneration in separation processes. Previously, the predictive capacity of the COSMO-RS method respect to VLE of mixtures (organic solvent+IL) is assessed and the correct transferability of the COSMO-RS results to Aspen Plus/Aspen HYSYS process simulators demonstrated.
This paper reports the results of a field investigation aiming at characterizing the morphology and hydraulics of both rills and ephemeral gullies (EGs) monitored at Sparacia experimental area, ...Sicily, Italy. The comparison between rill and interrill erosion measurements showed that sediment delivery processes occurred in some erosive events and that the rill erosion rate was dominant in many cases.
The measurements were used for testing both the empirical relationships between the channel (rill, EGs and gully) length and its eroded volume and among the morphological variables (length, width, depth and volume) describing the channelized process.
Finally, the rill and EGs hydraulic geometry was modelled by three well known power equations relating the discharge with the mean flow velocity, with the flow depth and with the width of each channel segment, respectively. The rill measurements also showed that the flow velocity was affected by the rill segment slope while the flow depth and width were controlled by the plot slope. Therefore, three equations, taking into account these slope effects, were proposed to estimate the hydraulic characteristics of the rills monitored at the Sparacia area.
► Rill and ephemeral gully erosion in Sicily, Italy. ► At event scale rill erosion is dominant in comparison with interrill erosion. ► The severity of the channelized erosion process can be estimated by channel length. ► A morphological similarity between rills and ephemeral gullies exists. ► Plot slope affects rill width and depth.
●The e-NRTL binary parameters for 171 binary electrolyte systems were obtained.●Parameters were fitted by non-linear regression of γ± vs. m data reported elsewhere.●The e-NRTL equation was ...implemented in Excel VBA and used in Aspen Plus via automation.●The obtained binary parameters predicted well the properties of multicomponent systems.
The main objective of the current work is to obtain and validate the binary interaction parameters of the e-NRTL model for different salts in water, using the data of mean ionic activity coefficients vs. molality compiled by Robinson and Stokes (Electrolyte Solutions, Dover Publications, 2012). This way, the interaction parameters τsalt,water and τwater,salt of the e-NRTL thermodynamic model for 171 binary (salt + water) electrolyte systems have been calculated by non-linear regression of the data available in the literature. The fitting was performed by the Marquardt-Levenberg algorithm which was computationally implemented in an Excel VBA homemade program. The e-NRTL equation was solved by using two different procedures: (i) included in the Excel VBA code or, (ii) implemented in Aspen Plus by linking the process simulator and the Excel VBA code via automation as the third-party software. The interaction parameters obtained by both approaches were able to adequately fit the experimental results. They were successfully validated by the thermodynamic prediction of multicomponent systems reported by other authors. Additionally, the current predictions were compared with those obtained with the parameters contained in the Aspen Properties database showing a significant improvement for several systems. Finally, this work demonstrates that it is possible enhancing the quality of the prediction of multicomponent systems with proper values of the binary electrolyte interaction parameters, without considering electrolyte-electrolyte interactions foreseen in the original e-NRTL model, which makes possible the simulation of processes containing a variety of chemical species regardless their nature.
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