scholarly journals Nanoparticles and Nanocrystals by Supercritical CO2-Assisted Techniques for Pharmaceutical Applications: A Review

2021 ◽  
Vol 11 (4) ◽  
pp. 1476
Author(s):  
Paola Franco ◽  
Iolanda De Marco
Keyword(s):  
Supercritical Co2 ◽  
Operating Conditions ◽  
Nanosized Particles ◽  
Future Perspectives ◽  
Active Compounds ◽  
Drug Particle ◽  
Effective Current ◽  
Polymeric Carriers ◽  
Site Of Action ◽  
Assisted Technologies

Many active ingredients currently prescribed show limited therapeutic efficacy, mainly due to their dissolution rate inadequate to treat the pathology of interest. A large drug particle size creates an additional problem if a specific site of action in the human body has to be reached. For this reason, active ingredient size reduction using micronization/nanonization techniques is a valid approach to improve the efficacy of active compounds. Supercritical carbon-dioxide-assisted technologies enable the production of different morphologies of different sizes, including nanoparticles and nanocrystals, by modulating operating conditions. Supercritical fluid-based processes have numerous advantages over techniques conventionally employed to produce nanosized particles or crystals, such as reduced use of toxic solvents, which are completely removed from the final product, ensuring safety for patients. Active compounds can be processed alone by supercritical techniques, although polymeric carriers are often added as stabilizers, to control the drug release on the basis of the desired therapeutic effect, as well as to improve drug processability with the chosen technology. This updated review on the application of supercritical micronization/nanonization techniques in the pharmaceutical field aims at highlighting the most effective current results, operating conditions, advantages, and limitations, providing future perspectives.

Preliminarily Design of Supercritical CO2 Compression Test System

2021 ◽  
Author(s):  
Geng Teng ◽  
Laijie Chen ◽  
Xin Shen ◽  
Hua Ouyang ◽  
Yubo Zhu ◽  
...  
Keyword(s):  
Simulation Model ◽  
Compression Test ◽  
Thermodynamic Model ◽  
Supercritical Co2 ◽  
Operating Performance ◽  
Test System ◽  
Operating Conditions ◽  
Working Fluid ◽  
Stable Operation ◽  
Test Loop

Abstract The centrifugal compressor is the core component of the supercritical carbon dioxide (SCO2) power cycle. It is essential to carry out component-level experimental research on it and test the working characteristics of the compressor and its auxiliary equipment. Building an accurate closed-loop simulation model of closed SCO2 compression loop is a necessary preparation for selecting loop key parameters and establishing system control strategy, which is also an important prerequisite for the stable operation of compressor under test parameters. In this paper, the thermodynamic model of compressor, pre-cooler, orifice plate and other components in supercritical CO2 compression test system is studied, and the simulation model of compression test system is established. Moreover, based on the system enthalpy equations and physical property model of real gas, the compressor, pre-cooler and other components in the test loop are preliminarily designed by using the thermodynamic model of components. Since the operating conditions are in the vicinity of the critical point, when the operating conditions change slightly, the physical properties of the working fluid will change significantly, which might have a greater impact on the operating performance of the system. So the operating performance and the parameter changes of key nodes in the test loop under different operating conditions are calculated, which will provide theoretical guidance for the construction of subsequent experimental loops.

Numerical Approach for Real Gas Simulations: Part II — Flow Simulation for Supercritical CO2 Centrifugal Compressor

2017 ◽  
Author(s):  
Swati Saxena ◽  
Ramakrishna Mallina ◽  
Francisco Moraga ◽  
Douglas Hofer
Keyword(s):  
Critical Point ◽  
Centrifugal Compressor ◽  
Supercritical Co2 ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Thermodynamic Quantities ◽  
3D Flow ◽  
Real Gas ◽  
The Real ◽  
Operating Range

This paper is presented in two parts. Part I (Tabular fluid properties for real gas analysis) describes an approach to creating a tabular representation of the equation of state that is applicable to any fluid. This approach is applied to generating an accurate and robust tabular representation of the RefProp CO2 properties. Part II (this paper) presents numerical simulations of a low flow coefficient supercritical CO2 centrifugal compressor developed for a closed loop power cycle. The real gas tables presented in part I are used in these simulations. Three operating conditions are simulated near the CO2 critical point: normal day (85 bar, 35C), hot day (105 bar, 50 C) and cold day (70 bar, 20C) conditions. The compressor is a single stage overhung design with shrouded impeller, 155 mm impeller tip diameter and a vaneless diffuser. An axial variable inlet guide vane (IGV) is used to control the incoming swirl into the impeller. An in-house three-dimensional computational fluid dynamics (CFD) solver named TACOMA is used with real gas tables for the steady flow simulations. The equilibrium thermodynamic modeling is used in this study. The real gas effects are important in the desired impeller operating range. It is observed that both the operating range (minimum and maximum volumetric flow rate) and the pressure ratio across the impeller are dependent on the inlet conditions. The compressor has nearly 25% higher operating range on a hot day as compared to the normal day conditions. A condensation region is observed near the impeller leading edge which grows as the compressor operating point moves towards choke. The impeller chokes near the mid-chord due to lower speed of sound in the liquid-vapor region resulting in a sharp drop near the choke side of the speedline. This behavior is explained by analyzing the 3D flow field within the impeller and thermodynamic quantities along the streamline. The 3D flow analysis for the flow near the critical point provides useful insight for the designers to modify the current compressor design for higher efficiency.

Influence of Equation-of-States on Supercritical CO2 Combustion

2020 ◽  
Author(s):  
K. R. V. (Raghu) Manikantachari ◽  
Scott M. Martin ◽  
Ramees K. Rahman ◽  
Carlos Velez ◽  
Subith S. Vasu
Keyword(s):  
Supercritical Co2 ◽  
Carbon Capture ◽  
Flame Structure ◽  
Compressibility Factor ◽  
Operating Conditions ◽  
Binary Interaction ◽  
Binary Interaction Parameter ◽  
Combustion Modeling ◽  
Equation Of States ◽  
Supercritical Combustion

Abstract Fossil fuel based direct-fired supercritical CO2 (sCO2) cycles are gaining the attention of industry, academia and government due to their remarkable efficiency and carbon capture at high-source temperatures. Modeling plays an important role in the development of sCO2 combustors because experiments are very expensive at the designed operating conditions of these direct-fired cycles. Inaccurate density estimates are detrimental to the simulation output. Hence, this work focuses on comprehensive evaluation of the influence and applicability various equation-of-states (EOS) which are being used in the supercritical combustion modeling literature. A state-of-the-art supercritical combustion modeling methodology is used to simulate counter-flow supercritical CO2 flames by using various equation-of-states. The results show that, using the corresponding state principle to evaluate compressibility factor is not accurate. Also, van der Waal type EOSs predictions can be as accurate as complex Benedict-Webb-Rubin EOSs; hence van der Waal EOSs are more suitable to simulate sCO2 combustor simulations. Non-ideal effects are significant under the operating conditions considered in this work. The choice of EOS significantly influences the flame structure and heat release rate. Also, assuming the binary interaction parameter as zero is reasonable in sCO2 combustion simulations.

Influence of Equation-of-States on Supercritical CO2 Combustion Mixtures

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
K.R.V. (Raghu) Manikantachari ◽  
Ramees K. Rahman ◽  
Scott M. Martin ◽  
Carlos Velez ◽  
Subith S. Vasu
Keyword(s):  
Supercritical Co2 ◽  
Carbon Capture ◽  
Flame Structure ◽  
Compressibility Factor ◽  
Operating Conditions ◽  
Binary Interaction ◽  
Binary Interaction Parameter ◽  
Combustion Modeling ◽  
Equation Of States ◽  
Supercritical Combustion

Abstract Fossil fuel based direct-fired supercritical CO2 (sCO2) cycles are gaining the attention of industry, academia, and government due to their remarkable efficiency and carbon capture at high-source temperatures. Modeling plays an important role in the development of sCO2 combustors because experiments are very expensive at the designed operating conditions of these direct-fired cycles. Inaccurate density estimates are detrimental to the simulation output. Hence, this work focuses on comprehensive evaluation of the influence and applicability of various equation-of-states (EOS) which are being used in the supercritical combustion modeling literature. A state-of-the-art supercritical combustion modeling methodology is used to simulate counter-flow supercritical CO2 flames by using various equation-of-states. The results show that using the corresponding state principle to evaluate compressibility factor is not accurate. Also, van der Waal type EOSs predictions can be as accurate as complex Benedict–Webb–Rubin EOSs; hence van der Waal EOSs are more suitable to simulate sCO2 combustor simulations. Non-ideal effects are significant under the operating conditions considered in this work. The choice of EOS significantly influences the flame structure and heat release rate. Also, assuming the binary interaction parameter as zero is reasonable in sCO2 combustion simulations.

scholarly journals Optimization and Comparison of Direct and Indirect Supercritical Carbon Dioxide Power Plant Cycles for Nuclear Applications

2011 ◽  
Author(s):  
Edwin A. Harvego ◽  
Michael G. McKellar
Keyword(s):  
Power Plant ◽  
Supercritical Co2 ◽  
Operating Conditions ◽  
Working Fluid ◽  
Primary System ◽  
Outlet Temperature ◽  
Reactor Outlet ◽  
Temperature Range ◽  
System Pressure ◽  
Intermediate Heat Exchanger

Results of analyses performed using the UniSim process analyses software to evaluate the performance of both a direct and indirect supercritical CO2 Brayton power plant cycle with recompression at different reactor outlet temperatures are presented. The direct supercritical CO2 power plant cycle transferred heat directly from a 600 MWt reactor to the supercritical CO2 working fluid supplied to the turbine generator at approximately 20 MPa. The indirect supercritical CO2 cycle assumed a helium-cooled Very High Temperature Reactor (VHTR), operating at a primary system pressure of approximately 7.0 MPa, delivered heat through an intermediate heat exchanger to the secondary indirect supercritical CO2 recompression Brayton cycle, again operating at a pressure of about 20 MPa. For both the direct and indirect power plant cycles, sensitivity calculations were performed for reactor outlet temperature between 550°C and 850°C. The UniSim models used realistic component parameters and operating conditions to model the complete reactor and power conversion systems. CO2 properties were evaluated, and the operating ranges of the cycles were adjusted to take advantage of the rapidly changing properties of CO2 near the critical point. The results of the analyses showed that, for the direct supercritical CO2 power plant cycle, thermal efficiencies in the range of approximately 40 to 50% can be achieved over the reactor coolant outlet temperature range of 550°C to 850°C. For the indirect supercritical CO2 power plant cycle, thermal efficiencies were approximately 11–13% lower than those obtained for the direct cycle over the same reactor outlet temperature range.

scholarly journals Corrosion and Erosion Behavior in Supercritical CO2 Power Cycles

2014 ◽  
Author(s):  
Darryn Fleming ◽  
Alan Kruizenga ◽  
James Pasch ◽  
Tom Conboy ◽  
Matt Carlson
Keyword(s):  
Carbon Dioxide ◽  
Stainless Steel ◽  
Intergranular Corrosion ◽  
Supercritical Co2 ◽  
Power Production ◽  
Operating Conditions ◽  
Working Fluid ◽  
Power Cycles ◽  
Power Cycle ◽  
Potential Issue

Supercritical Carbon Dioxide (S-CO2) is emerging as a potential working fluid in power-production Brayton cycles. As a result, concerns have been raised regarding fluid purity within the power cycle loops. Additionally, investigations into the longevity of the S-CO2 power cycle materials are being conducted to quantify the advantages of using S-CO2 versus other fluids, since S-CO2 promises substantially higher efficiencies. One potential issue with S-CO2 systems is intergranular corrosion [1]. At this time, Sandia National Laboratories (SNL) is establishing a materials baseline through the analysis of 1) “as received” stainless steel piping, and 2) piping exposed to S-CO2 under typical operating conditions with SNL’s Brayton systems. Results from ongoing investigations are presented. A second issue that SNL has discovered involves substantial erosion in the turbine blade and inlet nozzle. It is believed that this is caused by small particulates that originate from different materials around the loop that are entrained by the S-CO2 to the nozzle, where they impact the inlet nozzle vanes, causing erosion. We believe that, in some way, this is linked to the purity of the S-CO2, the corrosion contaminants, and the metal particulates that are present in the loop and its components.

scholarly journals Micronization of Curcuma xanthorrhiza Extract with Addition of PVP Using Supercritical CO2 as Anti-solvent

2021 ◽  
Vol 333 ◽  
pp. 08002
Author(s):  
Rucita Ramadhana ◽  
Sarah Duta Lestari ◽  
Syahna Almadilla ◽  
Rizky Prasetya ◽  
Siti Machmudah ◽  
...  
Keyword(s):  
Particle Size ◽  
Supercritical Co2 ◽  
Ethanolic Extract ◽  
Operating Conditions ◽  
Supercritical Antisolvent ◽  
Particle Size Increase ◽  
Mean Diameter ◽  
Particle Size And Morphology ◽  
Curcuma Xanthorrhiza ◽  
Size And Morphology

Curcuma xanthorrhiza Roxb, known as Temulawak or Javanese ginger, is a plant species. Its rhizomes are used as a medicinal herb. It contains curcumin as an active compound and ethereal oils mainly consisted of sesquiterpenes. In this work, Curcuma xanthorrhiza Roxb ethanolic extract was micronized with an addition of PVP using supercritical antisolvent (SAS) method. The ethanolic extract was obtained from dried Curcuma xanthorrhiza Roxb using soxhletation. For the micronization, the extracted compound solvent was a mixture of acetone and ethanol (90:10 (v/v)), while the supercritical CO2 was used as an antisolvent. The effect of operating conditions on the particle size and morphology was evaluated. Through this method, spherical Curcuma xanthorrhiza/PVP particles with mean diameter ranging from 191 ± 70 nm to 178 ± 57 nm were successfully formed. The particle size not significantly decreased as the pressure increased from 8 12 MPa. The addition of PVP is very effective to reduce the particle size, increase the solubility, and enhance the bioavailability of Curcuma xanthorrhiza extract. This work has the potential to improve the use of Curcuma xanthorrhiza in pharmaceutical and nutraceutical applications.

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