Dynamic generation of power function gradient profiles in a universal microfluidic gradient generator by controlling the inlet flow rates

We report a two-inlet universal microfluidic gradient generator capable of generating gradient profiles of the functional form xp in the same device by controlling only the inlet flow rates. We...

Continuous Separation Process of Water-in-Crude Oil Emulsion by Simultaneous Application of an Electrical Field Combined with a Novel Absorbent Based on Functionalised PolyHIPE Polymer

During the extraction process of crude oil, the removal of water from a high stability water-in-crude oil emulsions is life-threatening for the production of a profitable product. However, several technologies of separation exist today, e.g. stripping columns, centrifugal separators, coalescence separators, vacuum distillation systems and gravity separators, almost all of these approaches are not able to completely remove water from water-in-crude oil emulsions besides their high cost. In this study, the preparation of a high internal phase emulsion (HIPE) was achieved on a laboratory scale. Subsequently, it was polymerized and sulphonated to produce a hydrophilic macroporous polyHIPE polymer (PHP) called silane (vinyl trimethoxy silane) PHP with a relatively high surface area of 104 m 2/g. It demonstrates high water absorption capability in addition to its ability to remove surface active substances such as Mg, Ca, Na and Cl, from crude oil which cause crude oil emulsification. The rates of demulsification of water-in-crude oil emulsions were examined in high AC field under various emulsion inlet flow rates from 100 ml/min to 1500 ml/min and different applied voltages from 1-5 kV (equivalent to 14-69 kV/m) by using a model of an electrostatic separator combined with silane PHP as absorber. It was found that the best separation efficiency was 91% with applied voltage of 5 kV and emulsion inlet flow rate of 100 ml/min. When the spent silane PHP was reused in the demulsification process under similar conditions, a separation efficiency of up to 73% was achieved. Also, it was noticed that the separation efficiency was increased with the increase in applied voltage and reduction in the inlet flow rate of emulsion. Moreover, the original or spent silane PHP were able to remove the undesired metals present in the crude oil. Keywords: Demulsification; Emulsion flow rate; Separation efficiency; Electrostatic Separator; Electric field strength.

Investigation of the effects of main geometric parameters and flow characteristics on secondary flow losses in a turbine cascade

This paper presents numerical simulation results of a three-dimensional (3D) transitional flow in a stator cascade of an axial turbine. The influences of the main geometric parameters and flow characteristics including, the blade aspect ratio, pitch-to-chord ratio, inlet flow angle, and exit Mach number, on secondary flows development and end-wall losses, were studied. The numerical results were validated by the results of experiments conducted in the laboratory of the steam and gas turbine faculty of the Moscow Power Engineering Institute. The maximum difference between computed and experimental results was 2.4 %. The total energy losses decrease by 20 % when the exit Mach number changes from 0.38 to 0.8. Numerical results indicated that the blade aspect ratio had the most effect on secondary flow losses. The total energy losses increase by 46.6 % when the aspect ratio decreases from 1 to 0.25. The total loss of energy by 13.2 % decreases by increasing the inlet flow angle from 60 degrees to 90 degrees. Then by increasing the inlet flow angle from 90 to 110 degrees, the total loss rises by 3.6%. As the pitch-to-chord ratio increases from 0.7 to 0.75, the total energy losses are reduced by 12.2 %. Then by increasing the pitch-to-chord ratio from 0.75 to 0.8, the total energy losses increase by 6 %. As with experimental data, the numerical results showed that the optimal inlet flow angle and relative pitch for the cascade are 90 degrees and 0.75, respectively.

Microwave-assisted preparation of polyphosphoric acid in a continuous-flow reactor

Polyphosphoric acid (PPA) is widely used in inorganic salt production, petrochemical industry, electronic material preparation and other manufacturing industries. Conventional preparation methods of PPA has disadvantages of pollution, high energy consumption and long production time. To address this problem, microwave continuous-flow preparation may be a desirable way due to its advantages of environmentally-friendly, rapidity and high efficiency. Therefore, to explore the process of preparing PPA by microwave continuous-flow method, a continuous-flow microwave reactor was designed for the dehydration process of orthophosphoric acid to prepare PPA in this paper. The microwave-assisted dehydration process was studied in comparison with the conventional dehydration process and the “closed” microwave-assisted dehydration process in terms of energy efficiency, process times and treatment capacity. The effect of input microwave power, reduced pressure and inlet flow velocity of orthophosphoric acid on the performance of the dehydration process was studied. The results showed that the influence of the microwave power on the temperature rise process during dehydration is greater than that of the reduced pressure. Moreover, the inlet flow rate has a great impact on the treatment capacity and product quality of the dehydration process. Bedsides, the comparison with the other two methods showed that microwave heating can effectively shorten the dehydration time, and the continuous-flow treatment can effectively improve the treatment capacity of microwave heating. The perspectives of the process scale-up by continuous-flow microwave heating method is also discussed.

Turbine Design and Optimization for a Supercritical CO2 Cycle Using a Multifaceted Approach Based on Deep Neural Network

Turbine as a key power unit is vital to the novel supercritical carbon dioxide cycle (sCO2-BC). At the same time, the turbine design and optimization process for the sCO2-BC is complicated, and its relevant investigations are still absent in the literature due to the behavior of supercritical fluid in the vicinity of the critical point. In this regard, the current study entails a multifaceted approach for designing and optimizing a radial turbine system for an 8 MW sCO2 power cycle. Initially, a base design of the turbine is calculated utilizing an in-house radial turbine design and analysis code (RTDC), where sharp variations in the properties of CO2 are implemented by coupling the code with NIST’s Refprop. Later, 600 variants of the base geometry of the turbine are constructed by changing the selected turbine design geometric parameters, i.e., shroud ratio (rs4r3), hub ratio (rs4r3), speed ratio (νs) and inlet flow angle (α3) and are investigated numerically through 3D-RANS simulations. The generated CFD data is then used to train a deep neural network (DNN). Finally, the trained DNN model is employed as a fitting function in the multi-objective genetic algorithm (MOGA) to explore the optimized design parameters for the turbine’s rotor geometry. Moreover, the off-design performance of the optimized turbine geometry is computed and reported in the current study. Results suggest that the employed multifaceted approach reduces computational time and resources significantly and is required to completely understand the effects of various turbine design parameters on its performance and sizing. It is found that sCO2-turbine performance parameters are most sensitive to the design parameter speed ratio (νs), followed by inlet flow angle (α3), and are least receptive to shroud ratio (rs4r3). The proposed turbine design methodology based on the machine learning algorithm is effective and substantially reduces the computational cost of the design and optimization phase and can be beneficial to achieve realistic and efficient design to the turbine for sCO2-BC.

Effect of Emissary Vein on Hemodynamics of the Transverse- Sigmoid Sinus Junction

Objective: To investigate the effect of the blood flow direction and afflux location of emissary veins (EVs) on the hemodynamics of the transverse-sigmoid sinus (TS-SS) junction.Methods: A patient-specific geometric model was constructed using computed tomography venography (CTV) and 4D flow MR data from a venous pulsatile tinnitus (PT) patient. New EV models were assembled with the afflux at the superior, middle and inferior portions of the SS from the original model, and inlet and outlet directions were applied. Computational fluid dynamics (CFD) simulation was performed to analyze the wall pressure and flow pattern of the TS-SS junction in each condition.Results: Compared to the model without EVs, the wall pressure was greatly increased in models with inlet flow and greatly decreased in models with outlet flow. The more closely the EV approached the TS-SS, the larger the pressure in models with inlet flow, and the smaller the pressure in models with outlet flow. The flow streamline in the lateral part of the TS-SS junction was smooth in all models. The streamlines in the medial part were regular spirals in outlet models and chaotic in inlet models. The streamlines showed no obvious changes regardless of afflux location. The velocity at the TS-SS junction of inlet models were uniform, medium-low flow rate, while in control and outlet models were the lateral high flow rate and the central low flow rate.Conclusion: The flow direction and afflux location of EVs affect the hemodynamics of the TS-SS junction, which may influence the severity of PT.

Single Needle Option: An Alternative to Dual-Needle Access in Erythrocytapheresis in Patients with Sickle Cell Disease

Background: Erythrocytapheresis or red cell exchange (RCE) is an invaluable treatment option for patients with complications related sickle cell disease, including acute stroke, stroke prevention, acute chest syndrome, and recurrent pain crisis. The procedure entails the removal of each patient's red blood cells containing the abnormal sickle hemoglobin and replacing them with normal red blood cells carrying non-sickled hemoglobin. Adequate vascular access is essential for erythrocytapheresis to allow for high flow rates and various forms of access are used including peripheral veins and central venous access devices. Our center typically uses a single vortex port (Angiodynamics, Walnut Creek, CA) with placement of a peripheral IV at time of procedure in order to maintain a circuit for exchange. Using peripheral access reliably becomes particularly difficult in young patients and those that require multiple access over time due to scaring. To ensure a successful procedure in patients with poor peripheral access, a single-needle (SN) option for TPE (SN-TPE) that is available on Spectra Optia (Terumo BCT, Lakewood, CO) was used. The single-needle procedure utilizes intermittent, rather than continuous, flow, and thus requires extra procedure run time. One discontinuous cycle consists of "exchanging red cells," which is the drawing of blood and removal of the red cells, and "adjusting the volume in the reservoir," which is the returning of blood. These cycles continue until the procedure is complete. This procedure allows us to continue RCE in a select number of patients with poor vascular access. Methods: We evaluated our institutional experience on patients treated using single-needle RCE. In addition, information regarding each RCE session was collected including duration of procedure and inlet flow rate. Results: An average of 45 RCE procedures are performed each month. Patients are scheduled every 3 to 8 weeks, with an average of every 4-5 week frequency. We started the Single Needle option in July of 2019 on 3 patients: one adult aged patient and 2 pediatric patients. By the end of 2019 we had perform a total of 27 SN procedures. In 2020, we performed a total of 112 SN procedures, average of 9 procedures each month. As of the first 6 months of 2021, we have completed 35 SN procedures, averages 6 a month. In patients undergoing single needle exchange we were able to increase inlet flow rates from an average of 30-50ml/min to 60-80ml/min. This decreased the duration of run times from 120-198 min to 77- 119 min. Pre and post hemoglobin S% was comparable between dual and single exchange patients and there was no change in the interval between RCE sessions. Conclusion: With our increasing experience with single-needle RCE, our findings suggest that RCE can be successfully completed using the single-needle option with no impact on pre- and post-exchange hemoglobin S% levels. There was a reduction in the total length of procedure due to ability to maintain higher inlet rates and decreased time to obtain access for RCE. The single needle option also improved patient satisfaction due to more reliable access and negating need for peripheral IV access. Disclosures Munson: Terumo Medical Corporation: Consultancy, Honoraria, Speakers Bureau. Raj: Forma therapeutics: Consultancy; Terumo Medical Corporation: Honoraria, Speakers Bureau; Global biotherapeutics: Speakers Bureau.