[en] In the petrochemical industry, the synthesis of 2 ethyl-hexanol-oxo-alcohols (plasticizers alcohol) is of high importance, being achieved through hydrogenation of 2 ethyl-hexenal inside catalytic trickle bed three-phase reactors. For this type of processes the use of advanced control strategies is suitable due to their nonlinear behavior and extreme sensitivity to load changes and other disturbances. Due to the complexity of the mathematical model an approach was to use a simple linear model of the process in combination with an advanced control algorithm which takes into account the model uncertainties, the disturbances and command signal limitations like robust control. However the resulting controller is complex, involving cost effective hardware. This paper proposes a simple integer-order control scheme using a linear model of the process, based on active disturbance rejection method. By treating the model dynamics as a common disturbance and actively rejecting it, active disturbance rejection control (ADRC) can achieve the desired response. Simulation results are provided to demonstrate the effectiveness of the proposed method

[en] Highlights: • Cycled carbide slag from calcium looping cycles is used to remove HCl. • The optimum temperature for HCl removal of cycled carbide slag is 700 °C. • The presence of CO₂ restrains HCl removal of cycled carbide slag. • CO₂ capture conditions have important effects on HCl removal of cycled carbide slag. • HCl removal capacity of carbide slag drops with cycle number rising from 1 to 50. - Abstract: The carbide slag is an industrial waste from chlor-alkali plants, which can be used to capture CO₂ in the calcium looping cycles, i.e. carbonation/calcination cycles. In this work, the cycled carbide slag from the calcium looping cycles for CO₂ capture was proposed to remove HCl in the flue gas from the biomass-fired and RDFs-fired boilers. The effects of chlorination temperature, HCl concentration, particle size, presence of CO₂, presence of O₂, cycle number and CO₂ capture conditions in calcium looping cycles on the HCl removal behavior of the carbide slag experienced carbonation/calcination cycles were investigated in a triple fixed-bed reactor. The chlorination product of the cycled carbide slag from the calcium looping after absorbing HCl is not CaCl₂ but CaClOH. The optimum temperature for HCl removal of the cycled carbide slag from the carbonation/calcination cycles is 700 °C. The chlorination conversion of the cycled carbide slag increases with increasing the HCl concentration. The cycled carbide slag with larger particle size exhibits a lower chlorination conversion. The presence of CO₂ decreases the chlorination conversions of the cycled carbide slag and the presence of O₂ has a trifling impact. The chlorination conversion of the carbide slag experienced 1 carbonation/calcination cycle is higher than that of the uncycled calcined sorbent. As the number of carbonation/calcination cycles increases from 1 to 50, the chlorination conversion of carbide slag drops gradually. The high calcination temperature and high CO₂ concentration in the calcination of calcium looping decrease the chlorination conversions of the cycled carbide slag. Increasing the calcination time in the calcium looping is adverse to HCl removal and extending the carbonation time slightly improves the chlorination conversions. The microstructure of the cycled carbide slag shows an important effect on HCl removal capacity

[en] Highlights: • The thermal properties of a PCM with nanofibers are determined. • The solid-phase thermal conductivity scales exponentially with volume fraction. • The liquid-phase thermal conductivity is only enhanced beyond a critical percolation threshold. • The nanoscale interface resistance depends on the nanoparticle’s dimensionality. • The thermal diffusivity and volumetric heat capacity of the nanoenhanced PCMs are found. - Abstract: In many studies, carbon nanoparticles with high values of thermal conductivity (10–3000 W/m K) have been embedded into phase change thermal energy storage materials (PCMs) in order to enhance their bulk thermal properties. While a great deal of work to date has focused on determining the effect of these nanoparticles on a PCM’s solid phase thermal properties, little is known about their effect on its liquid phase thermal properties. Thus, in this study, the effect of implanting randomly oriented herringbone style graphite nanofibers (HGNF, average diameter = 100 nm, average length = 20 μm) on the bulk thermal properties of an organic paraffin PCM (IGI 1230A, T_melt = 329.15 K) in both the solid and liquid phase is quantified. The bulk thermal conductivity, volumetric heat capacity and thermal diffusivity of HGNF/PCM nanocomposites are obtained as a function of temperature and HGNF volume loading level. It is found that the property enhancement varies significantly depending on the material phase. In order to explain the difference between solid and liquid phase thermal properties, heat flow at the nanoparticle–PCM and nanoparticle–nanoparticle interfaces is examined as a function of HGNF loading level and temperature. To do this, the solid and liquid phase thermal boundary resistances (TBRs) between the nanoparticles and the surrounding PCM and/or between contacting nanoparticles are found. Results suggest that the TBR at the HGNF–PCM interface is nearly double the TBR across the HGNF–HGNF interface in both solid and liquid phases. However, both the HGNF–PCM and HGNF–HGNF TBRs are at least an order of magnitude lower when the PCM is in its solid phase versus when the PCM is in its liquid phase. Finally, the effect of nanofiber concentration on the PCM’s latent heat of fusion and melt temperature is investigated in order to determine the applicability of the HGNF/PCM nanocomposite in a wide variety of energy systems

[en] A modified process to enhance the latent heat of fusion of n-eicosane microcapsules in melamine-formaldehyde shells is suggested for application in textiles. Deviations in melt enthalpy and phase change temperatures were determined for produced microcapsules by differential scanning calorimetry. Thermo-regulation efficiency of eicosane-microcapsule-treated fabrics was evaluated via fitting the Newton cooling law to the experimental data, and a new constant, α, was defined as the thermal delay factor. Scanning electron microscopy images and particle size distribution analysis were consistent and the particle size was found to be between 0.5 and 2.7 μm. Melamine-formaldehyde/n-eicosane microcapsule composition was confirmed using a Fourier transform infrared spectrophotometry. The microcapsules developed showed excellent heat storage capacities, over 162.4 J/g, over melting and crystallisation ranges compared with previous studies undertaken in this field. - Highlights: • Modified eicosane microcapsules with the highest phase change enthalpies were made. • Newton cooling law was fitted to determine thermal delay in PCM-substrates. • Fine microcapsule units with diameters less than 0.5 μm were prepared. • All pliable PCM-substrates can be thermally assessed using thermal logging method

[en] The reversible reactions between ammine magnesium complex and ammonia are studied by volumetric method and the heterogeneous reaction kinetic analysis at a grain level. The influence of heat and mass transfer limitations at a pellet level on the overall absorption/desorption rate is sufficiently minimized with the reactive block and the micro-channel reactor. The pseudo equilibrium for Mg(NH₃)₂Cl₂ + 4NH₃ ⇔ Mg(NH₃)₆Cl₂ is not observed in the volumetric measurement. The kinetic parameters for the kinetic model are identified by the experimental data. The analysis reveals that the heterogeneous temperature or pressure distribution in the grain is the predominant factor on the overall absorption/desorption rate. - Highlights: • The thermodynamic properties were obtained without the pseudo equilibrium behavior. • The dependence of absorption/desorption rate on pressure and temperature was investigated. • The kinetic parameters for an empirical kinetic model were determined

[en] Up to now, the use of ammonia/water absorption cycles has been mainly limited to the production of refrigeration or air conditioning but due to the relatively high generator pressure some authors have proposed the integration in parallel of an expander to produce cooling and power simultaneously. This feature could provide many benefits in the future such as the use of solar thermal energy to partially cover the heating, cooling and electricity demand of a building. In the other hand the life cycle cost of the absorption system is improved because of the increase in the number of running hours in periods in which there is no demand for cooling but the demand for electrical power is still important. This paper shows a new combined absorption system using a scroll expander and three different working fluids using ammonia as refrigerant: ammonia/water, ammonia/lithium nitrate and ammonia/sodium thiocyanate. The scroll expander performance maps were obtained experimentally and modeled to predict the power production, rotational speed and exhaust temperature of the expander and included in the complete absorption cycle model build using Engineering Equation Solver (EES) Software. This system produces different amounts of cooling and power at the desired power/cooling ratio to cover varying demand profiles. - Highlights: • New combined absorption system using a scroll expander and three different working fluids. • Characterization the scroll expander with ammonia as working fluid. • Sensitivity to the heat source, sink and chilled water temperatures on the new combined absorption system

[en] This paper presents experimental results about CO₂ capture in a hybrid adsorbent/catalyst system at both laboratory and bench scale. The proposed novel system consists of a homogeneous mixture of a K-doped hydrotalcite and a high temperature Fe–Cr WGS catalyst in a single reactor, which was selected in previous works. Tests were performed using simulated syngas compositions (CO, CO₂, H₂, N₂, H₂O) and simplified binary mixtures (N₂/CO and N₂/CO₂) at temperatures in the range of 300 °C–500 °C and pressures up to 15 bar. The effect of contact time, process temperature and feed gas composition in the CO₂ capture capacity of the sorbent was investigated and main results are presented. Moreover, the sorbent showed catalytic activity towards the WGS reaction which was highly dependent on process temperature. Details on the influence of temperature in the catalytic activity of the sorbent are also described in this paper. The influence of temperature and volume ratio adsorbent/catalyst (V_ads/V_cat) in the performance of the hybrid system proposed is discussed in terms of CO conversion and CO₂ capture capacity of the sorbent

[en] Highlights: • Measurements of activity coefficients at infinite dilution using GLC. • 22 Organic solutes in the ionic liquid [BMIM][CH₃SO₄]. • The excess thermodynamic functions, the (gas + liquid) partition coefficients were calculated. • The solubility parameter of the IL [BMIM][CH₃SO₄] was determined by the regular solution theory. • The linear free energy relationship (LFER) analysis of the results was performed. - Abstract: Activity coefficients at infinite dilution (γ_i^∞) and (gas + liquid) partition coefficients (K_L) for organic solutes: alkanes, alkenes, alkyl benzenes, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, and chloromethanes in the ionic liquid (IL) 1-butyl-3-methylimidazolium methyl sulfate ([BMIM][CH₃SO₄]) have been measured by the (gas + liquid) chromatographic method in the temperature range of (313.15 to 363.15) K. The values of the partial molar excess enthalpies at infinite dilution (H^‾_i^E,∞) were derived from the temperature dependence of the γ_i^∞ values. The entropies (T_refS^‾_i^E,∞) and Gibbs free energies (G^‾_i^E,∞) of organic solutes in [BMIM][CH₃SO₄] at a reference temperature T_ref = 298.15 K were also calculated from the γ_i^∞ values. The solubility parameters of the IL [BMIM][CH₃SO₄] were also determined by the regular solution theory (RST). The linear free energy relationship (LFER) analysis of the results was performed to disclose molecular interactions operating between the IL and the individual solutes

[en] Graphical abstract: - Highlights: • Solubility of 5′-IMPNa₂ in various solvents was studied for the first time. • The solubility could be ranked as follows: water > methanol > ethanol > acetone. • Modified Apelblat equation gave the best correlating results. • Mixing Gibbs free energies, enthalpies, and entropies were predicted. • Solubility data and equations can optimise the crystallization conditions. - Abstract: The solubility of biological chemicals in solvents provide important fundamental data and is generally considered as an essential factor in the design of crystallization processes. The equilibrium solubility data of inosine-5′-monophosphate disodium (5′-IMPNa₂) in water, methanol, ethanol, acetone, as well as in the solvent mixtures (methanol + water, ethanol + water, acetone + water), were measured by an isothermal method at temperatures ranging from (293.15 to 313.15) K. The measured data in pure and mixed solvents were then modelled using the modified Apelblat equation, van’t Hoff equation, λh equation, ideal model and the Wilson model. The modified Apelblat equation showed the best modelling results, and it was therefore used to predict the mixing Gibbs free energies, enthalpies, and entropies of 5′-IMPNa₂in pure and binary solvents. The positive values of the calculated partial molar Gibbs free energies indicated the variations in the solubility trends of 5′-IMPNa₂. Water and ethanol (in the binary mixture with water) were found to be the most effective solvent and anti-solvent, respectively

[en] Highlights: • We report 0.1 MPa density data for four still poorly studied ionic liquids. • We analyze the density data within the group contribution concept. • Molar volume contributions of three particular atomic groups were determined. • The molar volume contribution of the alkyl inner CH₂ group is (16.99 ± 0.10) cm³ · mol⁻¹. • Standard reference density values for [C_nMIM][NTf₂] ionic liquids were developed. - Abstract: Experimental data over the temperature range from (262 to 365) K are presented on the 0.1 MPa densities for seven imidazolium and pyridinium based ionic liquids with hexafluorophosphate and bis(trifluoromethylsulfonyl)imide anion. Four of them almost have not been studied in this respect yet. The reported density data were obtained using a single-sinker buoyancy method. The estimated expanded combined uncertainty at 0.95 confidence level ranges from 0.1 kg · m⁻³ for [BMPy][PF₆] to 1.0 kg · m⁻³ for [EMIM][NTf₂], that is, from (0.8·10^-4 to 6.7·10^-4)ϱ (T = 298.15 K). The Krűss K100MK2 tensiometer was used to determine the buoyancy forces. For the contribution to the ionic liquid molar volume at T = 298.15 K and 0.1 MPa follows from the obtained density data for a CH₃ group bound to a nitrogen atom in the imidazolium ring a value of (17.65±0.16) cm³ · mol⁻¹, for a CH₃ group bound to a carbon atom in the imidazolium ring a value of (17.71±0.3) cm³ · mol⁻¹, and for an inner CH₂ group in the alkyl side chain the value of (16.99±0.02) cm³ · mol⁻¹, where 0.95 confidence level uncertainties are given arising from the data scatter. Nonlinearity of the dependence of the alkyl side chain contribution to the molar volume on the number of its carbon atoms limits the accuracy attainable using the group contribution method to about 0.1 cm³ · mol⁻¹, that is, 5·10^-4ϱ. A model is proposed to generate recommended values of density at 0.1 MPa for 1-C_n-3-methylimidazolium bis(trifluoromethylsulfonyl)imides with n=2 to 14 at temperatures from (260 to 473) K