In this study, the torque and horizontal load on an agitating shaft in an eccentric mixer with a MAXBLEND impeller at various impeller rotational speeds and eccentric conditions were measured in a turbulent state. The averages of both the torque and the horizontal load, and their standard deviations, corresponding to the amplitude of fluctuation, were calculated, and the causes of the fluctuation were investigated by FFT analysis. The average of torque was proportional to the square of the impeller rotational speed, and increased exponentially to 4.6 times the eccentric ratio. The standard deviation of the torque was smaller than the average torque. The increase in the average torque accompanying the increase in impeller rotational speed and eccentric length was summarized as a estimation equation for the average torque. In measuring of the horizontal load, the loads parallel to, and perpendicular to, the blade were measured independently. The average of these values was almost zero. The load perpendicular to the blade was one order larger than that parallel to the blade. The load perpendicular to the blade and the resultant load in parallel and perpendicular directions to the blade were proportional to the power of the impeller rotational speed and were an exponential function of the eccentric ratio. Based on this relation, equations for estimating the horizontal load were proposed.
An important problem for the vacuum gas oil (VGO) hydrocracking process is to control the product yield, which is difficult to measure online. In the present study, the performance of a single input single output (SISO) control loop provided for a pilot scale VGO hydrocracker is studied. The controller aims to set the yield of the process at the desired value by manipulating the reactor temperature. To do such a task, the dynamic model of the reactor is solved by the using conservation element/solution element (CE/SE) method; then, a PID (proportional–integral–derivative) controller, tuned using the genetic algorithm method, is applied to control the yield of the process. Results show that the reference yield of the process is accurately tracked that guarantees the production of the naphtha and middle distillate at the desired values. In addition, no temperature overshoot is observed, thereby protecting the catalyst from premature deactivation.
Microencapsulated phase change material (MEPCM) with dodecanol as the core material and urea-formaldehyde resin as the wall material was prepared using an in situ polymerization approach in this work. The effects of the ratio of core to wall material (0.5–1.5), the content of OP-100 (0.1–0.3 wt%), and the content of resorcin (1–3 wt%) on the mass content of dodecanol in the final product were evaluated by a complete 23 central composite rotatable design. The products obtained were characterized using a scanning electronic microscope (SEM), differential scanning calorimeter (DSC), and thermogravimetric analyzer (TGA). The MEPCMs obtained were spherical microparticles with a rough surface and an average diameter of about 1 µm. The content of dodecanol in the MEPCMs obtained is up to 64.7 wt%. The results from the TGA show that the microcapsules prepared have excellent thermal stability with a two-stage decomposition profile at considerably high temperatures (above 80°C). Finally, the optimum conditions were a ratio of core to wall material 1.5, the content of OP-100 0.24 wt%, and the content of resorcin 2 wt%.
The optimization of catalyst layer activity is essential for PEFCs to improve their performance. In this study, the relation between the structure of the nanofiber catalyst layer and catalyst layer activity, which includes reactivity and diffusivity, was examined. Carbon-alloy nanofiber, which is alloyed with nitrogen atoms and Pt free catalyst for oxygen reduction reaction, was used for the cathode catalyst. Four catalyst layers of nanofiber catalyst in different lengths from 0.80 to 6.4 µm were prepared and their performances in a half cell and membrane electrode assembly (MEA) were evaluated. The bulky catalyst layer with an increased pore volume at the large secondary pore size larger than 2 µm was formed with the longer catalyst. The MEA with the longer catalyst showed a higher performance. The bulky catalyst layer by using the longer catalyst can provide a higher utilization of the active sites and also promote mass transport.