Phase equilibria of quaternary LiCl–NaCl–MgCl2–H2O and NaCl–Na2B4O7–MgCl2–MgB4O7–H2O systems at 273 K were studied by isothermal dissolution. The isothermal solubility of each salt was measured. Based on the experimental data and the corresponding equilibrium solid phases, equilibrium phase diagrams and water content diagrams were drawn. The results show that the quaternary LiCl–NaCl–MgCl2–H2O system forms a double salt LiCl·MgCl2·7H2O at 273 K. The phase diagram contains two invariant points, five univariant curves and four crystalline regions. The crystalline regions are LiCl·2H2O, NaCl, MgCl2·6H2O and LiCl·MgCl2·7H2O, respectively. There are two invariant points, five univariant curves and four crystallizing fields in the quaternary NaCl–Na2B4O7–MgCl2–MgB4O7–H2O system at 273 K, and the corresponding crystallizing fields are NaCl, Na2B4O7·10H2O, MgCl2·6H2O and MgB4O7·9H2O.
An optical fiber probe (OFP) is an intrusive but useful device for bubble/droplet measurement in gas–liquid two-phase flows. Although previous researchers have invented various types of OFP and established their own probe systems, few techniques have been applied to measurements in practical machinery. In particular, successful examples of OFP for droplet measurement are extremely rare. We invented a single-tip OFP (S-TOP) for size/velocity measurement of submillimeter droplets. The difficulty of using S-TOP measurement in droplet flows, as is true with other OFPs and electric conductivity probes, is how to discriminate touch positions of the S-TOP on the droplet. To solve this difficult problem and improve the accuracy of the S-TOP, signal analysis of S-TOP was performed based on 3D ray tracing. Our ray-tracing simulation successfully revealed a very hopeful characteristic signal (named the post-signal) from a seemingly noisy peak; its intensity corresponded to the S-TOP’s touch position. Based on this characteristic of the post-signal, we developed a method of signal processing for practical measurement of droplet velocity, chord length, and number density through the S-TOP. This new method considerably reduced the difference in the measured results between the chord lengths and velocities through the S-TOP and through visualization, to less than 10%.
Air impingement is a cooling technology which applies to freezing, cooling and plastics industries. An air impingement device was set up to investigate the flow characteristics of air jets. The influences of the arrangement and jet height on air flow characteristics were investigated experimentally. An oil film technique was used to visualize the jet flow on the surface of the impingement plate, and a hot-wire anemometer was used to measure the air velocity between the orifice plate and impingement plate in order to study the vertical velocity distribution of air jets. In the experiments, the specific value of jet height (H) and orifice diameter (D) was adjusted in the range of 4 to 7, and the pressure of the plenum chamber was adjusted in the range of 50 to 200 Pa. The vertical velocities were measured at different specific value of the distance (Z, between measuring point and orifice plate) and orifice diameter (D) when H/D was 7. Based on the patterns of oil film and the air vertical velocity distribution of the air jets, the airflows under an in-line orifice plate and in a staggered orifice plate were analyzed and compared with each other. The results indicate that the two jet arrangements have an identical initial state out of the orifices; however, the oil film of the staggered array has more crosses and less obstruction in the impingement plate. In addition, the fastest drop of air velocity under the orifice was in the Z/D range of 3 to 5 and the staggered array had higher velocity than the in-line array. Accordingly, airflow in the staggered array is better than in the in-line array.
Extrudate swell is an important phenomenon occurring when high viscoelastic materials, such as rubber and rubber compounds, are extruded. In this work, the effects of relaxation time and relaxation mode on swell predictions using a nonlinear differential viscoelastic model, that is, the Giesekus model, are studied systematically for rubber extrusion in a capillary die. The corresponding 3D, steady-state finite element simulation for predictions of swelling is presented and compared with experimental data for validation. Velocity distribution, pressure drop and circulation flow in the die are analyzed and discussed through the simulation. The results of swell prediction reveal that three-relaxation mode of the Giesekus model with a wide range of relaxation times reproduce experimental data. In addition, the number of relaxation mode and relaxation time have remarkable effects on circulation flow at the die corner and some effect on other field variables.
In this study, macroporous ceramic particles were synthesized by emulsion-assisted self-assembly with or without the use of sacrificial templates. Sodium silicate was employed as an economical precursor for the synthesis, and hence industry-scale application of the particles can be expected with control over particle size distribution. After the removal of sodium from sodium silicate using an ion-exchange resin, the resultant aqueous silicic acid solution was emulsified in a continuous oil phase to form tiny droplets that act as micro-reactors for template-free synthesis of porous silica particles. The crumpling and folding of the thin silica shell inside the emulsion during heating resulted in the formation of porous particles without the use of templates. The particles were spherical with a number of irregular macropores. Macroporous silica particles with spherical cavities were also synthesized using polystyrene nanospheres as sacrificial templates and silicic acid as a precursor of silica. In a demonstrative application, the porous particles were used as coating materials in the fabrication of water-repellent surfaces by lotus effect, indicating that the particles can be potentially applied to self-cleaning surfaces.
This paper investigates the theoretical saturation sulfur capacity of a renewable wet flue gas desulfurizer, sodium phosphate buffer solution. The saturated pH value and desulfurization capacity in the sodium phosphate buffer solution were calculated by means of ion balance, dissolution equilibrium and numerical calculation software. The results were tested and verified by experiments. The results show that the change law and the result are consistent. The sulfur capacity increases with the increase of the concentration of phosphate in the buffer solution, which indicates that the theoretical calculation method is reasonable and feasible. The results can provide basic data and reference for phosphate flue gas regeneration desulfurization processes, such as the liquid–gas ratio, solution pH value, and phosphoric acid concentration.
Aluminophosphate molecular sieves (AlPO-5) were substituted with seven metals (Ca, Co, Mg, Ni, Sr, Cr and Fe). From XRD measurement, all patterns of seven substituted AlPO-5 were identical to that of the AFI structure. Except for Cr substituted AlPO-5, they were mainly in a hexagonal pillar structures based on the SEM images. For Mg, Ni, Sr and Fe substituted AlPO-5, the water adsorption capacity at 30°C and the difference in the amount of adsorbed water between 30°C (adsorption temperature) and 100°C (desorption temperature) increased by the substitution. Although, for Fe substituted AlPO-5, the initial water adsorption rate was slightly decreased by the substitution, the water desorption temperature was equal for the temperature of AlPO-5. This is because Fe substituted AlPO-5 had about 1.8 times water adsorption capacity at 30°C and was able to be regenerated at 100°C, Fe substituted AlPO-5 was the most advantageous adsorbents.
Batch distillation is a useful separation technique for obtaining a pure product from a multi-component mixture. However, it is less energy-efficient than continuous distillation. This paper describes the system we developed for an internally heat-integrated batch distillation column (Batch or Semi-batch HIDiC) to minimize the energy consumption of the batch distillation process. We simulated the isopropyl alcohol dehydration process as a non-ideal system. The applicability of the system was examined using a commercial process simulator, Aspen Plus Dynamics®, to evaluate energy-saving performance. The energy evaluations of the Batch and the Semi-batch HIDiC model were compared against the conventional batch distillation model. It was found that with the Semi-batch HIDiC, this system has the potential to reduce process time and energy consumption more effectively than with conventional batch distillation.
Microscopic-scale trenches that were formed on silicon wafers were filled with polyamic acid (PAA) and polyimide (PI) that consisted of the pyromellitic dianhydride (PMDA)-2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFDB) pair with the aid of supercritical carbon dioxide (scCO2) and 20 mol% N,N-dimethylformamide (DMF) at 50 and 75°C and at monomer concentrations of 2.0×10−2 mol/dm3 each. Most of the trenches were well filled with the polymer, which consisted mostly of PAA. Moreover, PAA and PI that consisted of the PMDA-4,4′-diaminodiphenyl ether (ODA) pair was also investigated at deposition temperatures ranging from 50 to 150°C and at monomer concentrations of 2.0×10−2 mol/dm3 each. The trenches were completely filled with PAA and PI at 50°C. Slight shrinkage of the deposited polymers inside the trenches was observed after thermal imidization.
Global warming is a serious problem that must be urgently addressed. Synthesis gas can be produced via the dry reforming of methane using CO2. In this study, a kaolin-supported nickel catalyst was investigated for the production of synthesis gas. In addition, the effect of doping with cesium or mixed potassium and sodium-based promoters on the desired catalyst was studied, and it was found that the promoter enhanced the conversion and stabilized the H2/CO ratio. The catalyst containing 3% mixed potassium–sodium promoter showed excellent catalytic performance, having an initial CH4 conversion as high as 74.4% and a steady H2/CO ratio of almost unity. The catalysts were also characterized using nitrogen adsorption–desorption isotherms, X-ray diffraction, thermogravimetric analysis, thermal programmed oxidation, and thermal programmed reduction.
Metal halides are promising ammonia (NH3) absorption/desorption materials for hydrogen energy transport. In this study, a new NH3 carrier material, Ca0.5Sr0.5(NH3)8Cl2, was synthesized, and its crystal structure and NH3 desorption properties were analyzed. The crystal structure of the new material was orthorhombic (space group: Pnma) at 296±2 K, and was similar to those of Ca(NH3)8Cl2 and Sr(NH3)8Cl2. Its crystal volume was intermediate between those of Ca(NH3)8Cl2 and Sr(NH3)8Cl2, and its NH3 desorption equilibrium pressure (490 kPa) was also intermediate between those of Ca(NH3)8Cl2 (583 kPa) and Sr(NH3)8Cl2 (420 kPa) at 342 K. Thus, the NH3 desorption properties of Ca1−xSrx(NH3)8Cl2 may be controlled by varying the value of x.