Vapour-liquid phase equilibria and thermodynamic properties of solutions of the ethylbenzene and n-alkylbenzenes binary systems

The methods of theoretical description of the patterns of changes in thermodynamic properties depending on the composition and structure of solution components are a priority direction in the development of the theory of solutions. This article is devoted to the establishment of relationships between the thermodynamic properties, composition of solutions, and the structure of their components. The study of the thermodynamic properties of binary solutions formed by a common solvent (ethylbenzene) and substances of the homologous series of n-alkylbenzenes contributes to the establishment of the aforementioned relationships. In the production of ethylbenzene and its homologues, solutions based on n-alkylbenzenes are quite common. Alkylbenzenes are widely used in various fields of science and chemical technology as solvents, extractants, and plasticisers. Using the ebuliometric method, we measured the boiling points of solutions of four binary systems formed by ethylbenzene and n-alkylbenzenes under various pressure values. Compositions of equilibrium vapour phases of the binary systems were calculated using the obtained isotherms of saturated vapour pressure of the solutions. Using the Runge-Kutta method, the composition of the vapour phases of the solutions of the systems was calculated by the numerical integration of the Duhem–Margules equation on a computer. The obtained data on the vapour-liquid equilibrium became the basis for calculating the thermodynamic functions of the systems’ solutions. The Gibbs and Helmholtz energy values, the enthalpies of vaporisation and mixing, the internal energy, and entropy of solutions were calculated. The thermodynamic properties of the solutions were calculated using a comparison of the values baed on two standards: an ideal solution and an ideal gas. It was found that the values of the Helmholtz energy linearly depend on the molar mass of the substance (the number of –CH2– groups in a molecule) in the homologous series of n-alkylbenzenes. An increase in the Helmholtz energy values for n-alkylbenzenes in the homologous series is associated with a linear increase in the molar volume of liquid substances and an exponential decrease in the saturated vapour pressure of substances. For binary solutions of constant molar concentrations formed by ethylbenzene and n-alkylbenzenes, the Helmholtz energy linearly depends on the molar mass (number of –CH2– groups in the molecule) of n-alkylbenzene in the homologous series. We obtained an equation that makes it possible to predict the thermodynamic properties of solutions of binary systems with high accuracy. The equation accelerates the process of studying vapour-liquid phase equilibria and thermodynamic properties of solutions of binary systems by 300 times. The determined patterns confirm the hypothesis of the additive contribution of functional groups to the thermodynamic properties of solutions. This hypothesis underlies the statistical theory of group models of solutions. The thermodynamic patterns determined by this study can also be used to solve a wide range of technological issues in the chemical industry.

In situ monitoring of hydrothermal reactions by X-ray diffraction with Bragg–Brentano geometry

This note describes an autoclave chamber developed and constructed by Anton Paar and its application for in situ experiments under hydrothermal conditions. Reactions of crystalline phases can be studied by successive in situ measurements on a conventional laboratory X-ray diffractometer with Bragg–Brentano geometry at temperatures <483 K and saturated vapour pressure <2 MPa. Variations in the intensity of X-ray diffraction reflections of both reactants and products provide quantitative information for studying the reaction kinetics of both dissolution and crystal growth. Feasibility is demonstrated by studying a cementitious mixture used for autoclaved aerated concrete production. During a period of 5.7 h at 466 K and 1.35 MPa, the crystallization of torbermorite and the partial consumption of quartz were monitored.

Rainfall Intensity and Evapotranspiration Patterns Nexus over Nigeria in Different Solar Cycles

The study employed Mass – Transfer Model (MTM) to estimate evapotranspiration (ET) from 12 selected locations spread across three climatic zones over Nigeria at intervals of 30 years (1988 and 2018) depicted by different solar cycles. Based on this finding the impacts of rainfall intensity on evapotranspiration patterns over Nigeria were investigated. Daily averaged values of wind speed at 2 m from soil, air temperature and relative humidity for 12 selected stations across Nigeria were employed for 1988 and 2018. The actual vapour pressure and saturated vapour pressure were estimated. A correlation between evapotranspiration with rainfall intensity was established to determine impacts of rainfall intensity on evapotranspiration patterns over Nigeria in solar maxima and minima scenarios. The results showed that ET was higher in 2018 than 1988 in 3 out of 4 stations in tropical monsoon; in tropical savannah and only Ibadan and Akure had a reduction in these values when 1988 was compared with 2018. Lowest values of ET was observed between August and October corresponding to the peak of rainy season. 7 stations out of 12 were influenced by solar minima phenomenon namely Port Harcourt, Owerri, Enugu, Ibadan, Minna, Borno and Gusau. The lowest values of ET were recorded at Calabar and Port Harcourt for both 1988 and 2018 while the highest values were observed at Borno for 1988 and Sokoto for 2018. Rainfall intensity had greater impacts on ET values in tropical monsoon than any other climatic zone in Nigeria.

Hydrometeorological Study of Saturated Vapour Pressure (SVP) of Warri, Nigeria

The amount of water vapour present in the air is indirectly expressed through vapour pressure and for any given temperature there is a limit for water vapour that can be held by air. If the air is holding water vapour which is equal to the maximum that it can hold at a given temperature, then the air is said to be saturated. Hydrometeorological study was carried out using vapour pressure (VP) and maximum temperature data for Warri through 2009 – 2018 (10 years) Saturation Vapour Pressure (SVP) were estimated. A graph is established showing the relationship between the Saturation Vapour Pressure (SVP) and the temperature also the graphical representation showing variational trend of SVP and VP were plotted. The study shows the dew point (Td) ranging from 29.9°C to 31.5°C which explained the likely rainfall at any temperature below Td. The study also confirmed increase in SVP bringing increase in Temperature and the variational trend shows the same pattern all through.

Water condensation and transport on bioinspired triangular patterns with heterogeneous wettability at a low temperature

Desert beetles and cactus plants collect water from fog in arid regions. The desert beetle uses heterogeneous wettability to transport water to its mouth. A cactus uses conical spines which provide Laplace pressure gradient to transport water to its base. In this study, bioinspired triangular patterns with various wettability and different from the surrounding regions were investigated to transport condensed water from ambient air. A low temperature of 5°C was used to decrease saturated vapour pressure to promote water condensation. Results from this study can be used to enhance the performance of water collection systems. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology’.

SCR-Catalyst Utilisation and Mixing Comparison Using a Novel Biomimetic Flash-Boiling Injector

NOx pollution from Diesel engines causes over 10 000 premature deaths annually and the trend is increasing. In order to decrease this growing global problem, exhaust after-treatment systems for Diesel engines have to be improved. The most common SCR systems in the market place inject an aqueous Urea solution, DEF that evaporates prior the catalytic surface of the SCR-catalyst. Due to a catalytic reaction within the catalyst, NOx is converted nominally into Nitrogen and Water. Currently, the evaporative process is enhanced by aggressive mixer plates and long flow paths; these, negatively, create extra exhaust back pressure and cool the exhaust gases decreasing engine and catalyst efficiency. To achieve future emission legislation targets SCR efficiency has to be improved especially under low catalyst temperature conditions, plus Ammonia slip has to be avoided as it is now legislated against. Swedish Biomimetic’s novel μMist® platform technology, inspired by the Bombardier Beetle, injects a hot, effervescent, finely atomised, highly dispersed spray plume of DEF into the exhaust stream. This is achieved by raising the temperature of the DEF, in a closed volume, above its saturated vapour pressure. The DEF is then rapidly released creating effervescent atomisation. This study investigates a back to back study of the evaporating and mixing behaviour of the μMist® injector and a class leading DEF injector. The test conditions are with and without a mixer plate and the use of two different flow path designs. Spray distribution across the face of the catalyst is assessed by measuring NOx conversion whilst Ammonia slip is also measured post catalyst. This report describes how the novel μMist® injector significantly increases NOx conversion and catalyst surface usage whilst considerably reducing Ammonia slip.

Engineering applications of Bernoulli’s equation

In this chapter it is shown how Bernoulli’s equation can be applied to practical fluid-flow problems. In the case of internal flows, such as that through a Venturi tube, it is also necessary to use the continuity equation to relate changes in cross-sectional area to changes in flow velocity. For liquid flows it is shown that for sufficiently high flowspeeds the static pressure could fall below the saturated vapour pressure and lead to cavitation. The designs of various flow-measuring devices, including the orifice-plate flowmeter, the Venturi-tube flowmeter, and the Pitot tube, are based on Bernoulli’s equation. The changes in flow velocity occurring in flow through a wind-tunnel contraction are explained by Bernoulli’s equation.

Investigating Multiphase Flow Phenomena in Fine-Grained Reservoir Rocks: Insights from Using Ethane Permeability Measurements over a Range of Pore Pressures

The ability to quantify effective permeability at the various fluid saturations and stress states experienced during production from shale oil and shale gas reservoirs is required for efficient exploitation of the resources, but to date experimental challenges prevent measurement of the effective permeability of these materials over a range of fluid saturations. To work towards overcoming these challenges, we measured effective permeability of a suite of gas shales to gaseous ethane over a range of pore pressures up to the saturated vapour pressure. Liquid/semiliquid ethane saturation increases due to adsorption and capillary condensation with increasing pore pressure resulting in decreasing effective permeability to ethane gas. By how much effective permeability to ethane gas decreases with adsorption and capillary condensation depends on the pore size distribution of each sample and the stress state that effective permeability is measured at. Effective permeability decreases more at higher stress states because the pores are smaller at higher stress states. The largest effective permeability drops occur in samples with dominant pore sizes in the mesopore range. These pores are completely blocked due to capillary condensation at pore pressures near the saturated vapour pressure of ethane. Blockage of these pores cuts off the main fluid flow pathways in the rock, thereby drastically decreasing effective permeability to ethane gas.