In this paper, a modified three-parameter Lee–Kesler-like corresponding states model is presented to calculate the vapor pressure of pure refrigerants and refrigerant mixtures by using two reference fluids (R13 and R227ea). A new scaling parameter is proposed in the model to substitute for the classical acentric factor. The modified model shows a good accuracy over a wide range of temperatures and especially in the low-temperature region when compared to other Lee–Kesler-like corresponding states models such as Lee–Kesler, Teja, and Estela-Uribe.
The present study investigates deformable spherical gel particles that were packed in a column to separate silica particles. Spherical dimethylacrylamide gel particles with a mean diameter of 40 µm were polymerized in a water-in-oil suspension. The pressure loss during water permeation at varying flow rates of 10–50 mL h−1 through the gel-packed column at various heights was determined. The pressure loss increased exponentially with an increase in permeation time. This exponential increment is attributed to a deformation of the gel particles. Suspensions that contain silica particles with diameters of 0.12, 1.0, or 10 µm flowed, which indicates that larger silica particles were trapped within gaps of the packed gel at the top of the column; whereas, smaller particles were trapped within gaps of the deformed gel at the bottom of the column. The deformation pitch of gel particles that were packed in a column had a distribution in the flow direction to achieve particle separation at each position in a flowing silica-particle suspension.
Macroporous Co3O4–MgO composites with uniform pores of 0.3–1.0 µm were successfully fabricated for the first time by the sol–gel method using poly(methyl methacrylate) (PMMA) particles as a template. The macropore size and BET surface area were easily controlled by selecting a proper size of the commercial PMMA microspheres. In addition, the composites showed smaller Co3O4 particles than the catalysts prepared by the conventional impregnation method. High surface area composite catalysts with controlled porous structure exhibited a higher methylene blue degradation activity in the presence of Oxone as an oxidant than conventional supported catalysts. Because good dispersion of the active Co3O4 species is a key factor to enhance the catalytic activity, this finding could be attributed to the good mixing of Mg and Co precursors, a distinct advantage of the sol–gel technique.
Engineering plastic is used as a replacement for metal structural parts, in particular in the automotive industry, aiming at its lightweight effect that leads to the reduction of carbon dioxide emission. Design of the engineering plastic parts requires a broad range of expertise, which are unable to be covered by one company. For effective product design, activities and information related to the design should be arranged across the related companies such that required qualities can be designed systematically. Such companies appear to be well collaborated; however, their design work is actually separated on company basis. Although the computer aided engineering (CAE) environment is applied to processes of the design, the CAE environment is not utilized properly, which does not contribute to optimizing the processes. In order to optimize the processes with utilizing the CAE environment, the processes need to be organized so as to provide design-related information for each design activity by clarifying requirements and specifications of the activities. In this paper, we proposed a consistent business process model of the engineering plastic parts design with a template that has structured PDCA (Plan, Do, Check, Action) cycles for clearly defining activities related to the processes. Then, the current process of product design (“As-Is”) was analyzed by the consistent business process model (“To-Be”). As a result, the root cause of the current process was identified to inconsistent engineering standards that are used in CAE simulations. Finally, two countermeasures to overcome the company-based unfavorable structure were proposed for utilizing the CAE environment in the design process, which leads to systematizing the design process.
Three bioenergy technologies, gasification, Biodiesel fuel production, and H2–CH4 fermentation processes, were modeled using ASPEN PLUS. A comparative performance was analyzed for different regions and scales. The proportions of feedstock were set corresponding to urban, suburban and rural regions. Verification of the simulation with our experiment indicated adequate validation to simulate using our model designs. Advantage of scale was found in the H2–CH4 fermentation process, while total efficiency in the gasification process was considered to be affected greater to feedstock proportion by region category than to scale. Then, combined system of the three processes was simulated to assess advantages to the combining bioenergy technologies. Compared with the non-combined system, the combined system has high efficiencies because sludge and glycerol discharged from the three individual processes were fed again as feedstock into the combined system, and the sludge for the combined system was dried using waste heat exhausted from gas engine.
Seawater injection into oil reservoirs for secondary oil recovery is frequently accompanied by souring (increased sulfide concentrations) in crude oil. The hydrogen sulfide produced by microbiological sulfate reduction in the seawater causes various problems, including corrosion of tubing materials and deterioration of crude oil. Sulfate-reducing bacteria (SRBs) play major roles in souring. However, under high pH (>9), most microbes (including SRBs) cannot grow. Moreover, it is known that iron corrosion is theoretically negligible under the alkaline condition. To investigate new approaches to simultaneously control souring and metal corrosion, we analyzed souring under high-pH conditions. NaOH was added to adjust the pH clean seawater (ca. pH 8) to 11, or 13. Then, a carbon steel test coupon was incubated for 123 d and supplemented with microbes separated from oil field water (OFW) and crude oil. At pH 11 and pH 13, the corrosion rate of the test coupon was decreased. Additionally, souring did not occur at pH 11 and 13, although it took place at pH 8 with microbes. Next-generation sequencing analysis of the 16S rRNA gene revealed drastic changes in the microbial consortia for pH 8 after incubating for 111 d. Desulfotignum, which shows a high identity compared to that of toluene-utilizing SRB, became dominant. It is thought to contribute a biological souring by utilizing toluene in the crude oil at pH 8. On the other hand, at pH 11, the microbial consortia did not change significantly after 111 d of incubation. At pH 13, the microbial consortia drastically changed compared with that of initial condition (OFW) due to cell lysis. That is, even under strict conditions (e.g., pH 13), some bacteria are not lysed, increasing their relative ratio without growth. Alkaline addition could inhibit not only metal corrosion but also biological souring.
Nano Microbial Cellulose (MC) has many applications in producing biocomposites such as biodegradability, lightness, purity and high specific area. Therefore, many studies focus on improving characteristic and enhancing the amount of production. In this study, mechanical properties of MC are evaluated by investigating the effect of some medium condition parameters like surface area to volume ratio, type of strain, kind of nutrient and cultivation time. Two different kinds of strains such as Acetobacter xylinum BPR2001 and Acetobacter xylinum AT have been cultivated in an HS and molasses mixture culture medium for 10 and 20 d with a surface area to volume ratio of 0.25 and 0.75, and the mechanical properties of specimens were assessed. According to the obtained results, the tensile strength of produced MC from HS culture medium with a 0.25 (20-d) surface area to volume ratio by Acetobacter xylinum BPR2001 is 58% more than Acetobacter xylinum AT, and its tensile Modulus is also improved by 63%. The results indicated that increasing the tensile strength and tensile Modulus is directly related to the time of growth. In addition, the tensile strength and tensile Modulus decrease considerably whenever the surface area to volume ratio increases. The 20-d MC produced by Acetobacter xylinum AT in a 0.25 surface area to volume ratio represents higher tensile strength (2.5 times) and tensile modules (2.2 times) than the other. MC produced in molasses culture medium shows 12% and 36% growth in tensile strength and tensile modulus, respectively. Therefore, MC produced by Acetobacter xylinumBPR2001 with a 0.25 surface area to volume ratio is an adequate alternative which can be applied for biocomposite.
Oxygen-blown co-gasification behavior in an entrained down-flow gasifier was investigated experimentally, using pulverized woody biomass and pulverized coal, at various mixing ratios, as the gasification fuel. The gasification temperature was controlled to over 1200 K and the oxygen ratio (O2/O′2) was varied during the gasification experiments. The temperature of the gasifier and the composition and volume of the produced gas were measured; the carbon conversion, cold gas efficiency, and overall apparent reaction rates were calculated to evaluate the co-gasification behavior. The gasification temperature and composition of the produced gas varied significantly with the mixing ratio and oxygen ratio. The highest gasification temperature at the same oxygen ratio was observed for the fuel containing 20% woody biomass, due to enhanced oxidation reaction of the feedstock. The carbon conversion increased upon mixing woody biomass when compared to coal, due to the increased volatile content in the feedstock, but varied with the mixing ratio. The fuel ratio of the feedstock was identified as an important parameter for the cold gas efficiency and overall apparent reaction rate, which had a negative correlation with the fuel ratio when the oxygen ratio remained the same.