Transient Parameters Research Articles

Performance Evaluation of Hydroponics Control Systems for pH, Temperature, and Water Level Control

This study evaluates different control algorithms used in a hydroponic farming system to improve the quality of farm produce and resource efficiency. It focuses on three key hydroponic control parameters(potential hydrogen (pH), water level, and temperature control). Mathematical models are derived from the literature to represent hydroponic environments. These models are used for simulation purposes in MATLAB software to implement various control algorithms to evaluate their performance against each other and the system requirements utilizing transient performance parameters. Transient performance parameters are overshoot, settling time, rise time ,and steady-state error. The various control algorithms are fuzzy logic (FL), Proportional Integral Derivative (PID), and Proportional Integral Derivative-Fuzzy logic controller (PID-FL). This paper examines the performance of the hybrid PID-FL controllers compared to the most commonly used fuzzy logic and PID controllers. The result of the work shows that PID-FL is generally better for all the system models, making it more applicable.

Effects of the Broken Kernel on Heat and Moisture Transfer in Fixed-Bed Corn Drying Using Particle-Resolved CFD Model

To investigate the pore structure distribution and the coupled heat and moisture transfer during the drying process of the grains, this study focuses on fixed-bed corn drying with varying levels of broken kernel rate. A model of internal flow and conjugate heat and mass transfer was established for the drying process. Random packing models of whole and half corn kernels with different proportions were generated using rigid body dynamics (RBD), and the porosity, airflow distribution, and coupling of temperature and moisture transfer in fixed beds with different levels of broken kernel rate were analyzed. A fixed-bed corn drying device was developed, and the effects of broken particle contents of 0%, 10%, 20%, and 30% on drying characteristics were studied. The research findings reveal that the radial porosity in the fixed bed exhibits an oscillating distribution, with the localized porosity decreasing as the broken kernel rate increases. Increasing the broken kernel rate intensifies the curvature of the airflow paths within the fixed bed, increasing the pressure drop in the bed. The broken kernels fill the gaps between the whole kernels, improving the uniformity of the velocity distribution within the fixed bed. Under various packing models, the average discrepancy between pressure drop obtained from Particle-resolved Computational Fluid Dynamics (PRCFD) simulations with experimental remains below 15%. The increase in broken kernel rate within the fixed bed enlarges the heat transfer area, resulting in an elevation of the transient heat transfer characteristic parameters during drying. Simultaneously, the broken kernel rate increases the surface area of mass transfer, thereby enhancing the moisture transfer rate within the fixed bed. Compared to the fixed bed without broken kernels (0%), which requires 560 min to dry the corn pile to a safe moisture of 14% (d.b.), the drying time is reduced by 60 min, 100 min, and 130 min for the respective broken kernel contents of 10%, 20%, and 30%, respectively. The PRCFD method successfully simulates the processes of convective heat and mass transfer in the fluid phase and thermal and mass diffusion in the solid phase, exhibiting a strong correlation with experimental data.

Chemical kinetic analysis on the auto‐ignition characteristics of natural gas–diesel dual‐fuel combustion under engine‐relevant conditions

AbstractWith the advent of energy crisis and stringent emission regulations, natural gas (NG)/diesel dual‐fuel engines have entered the popular view. In this paper, the accurate boundary conditions are determined by the Converge model and the transient parameters were introduced into the chemical kinetics model to make the operating conditions more closely match the actual engine operating conditions. The effects of different methane/n‐heptane ratios, initial temperatures, initial pressures, and equivalence ratios on the IDT of methane/n‐heptane fuel mixtures were analyzed using comprehensive chemical kinetic tools such as mole fraction analysis, ROP analysis, and sensitivity analysis. The IDT of methane/n‐heptane mixture decreased significantly with increasing the equivalence ratio, initial pressure, and the proportion of n‐heptane in the mixture, but the change of temperature was more complicated for the IDT. The NTC behavior of methane/n‐heptane mixture was also affected by the NTC behavior of n‐heptane. With the increase of initial temperature, the consumption of methane and n‐heptane appeared to be significantly accelerated. The peak of radicals and intermediate groups appeared earliest and had the highest radical concentration when the n‐heptane content was 30%. With the increase of initial pressure, the peak moments of the six radicals were further advanced, but the mole concentrations of O, OH, H radicals decreased significantly. This paper not only provides a reference for the design of NG/diesel dual‐fuel engines, but also provides a theoretical basis and data support for improving the ignition and initial condition setting strategies of the engines.

Russian Civilization: Civilizational Approach in Political Theory

Discussions about the applicability of the civilizational approach in political science correlate with methodological and discursive rethinking of linear philosophical and political interpretive projects. The search for new epistemological and ontological optics of modern political constructions is largely focused on the value-symbolic parameters underlying the civilizational approach. The civilizational paradigm is one of the conceptual schemes of political theory, which makes it possible to interpret political institutions, processes, and world politics through the lens of more stable and deeper factors - value systems and culture. Becoming the identifying basis of politics and the legitimizing ideological and semantic content of instrumental strategies, the civilizational approach appeals to the multiplicity and equality of the paths of historical and political formation. In political discourse, the relevant intentions are the plots of ensuring the completeness of sovereignty, historical memory and falsification of history, a common value-semantic space, national unity, and many others. The point of concentration of scientific and ideological-political search is the definition of the civilizational status of Russia. According to the authors, giving Russia a civilizational status allows us to offer adequate explanations of its socio-political ontology and phenomenology, stable and transient parameters, invariant and innovative characteristics. The emphasis is on the metaphysics of Russian statehood as determined by the specifics of civilization.

Preserving microgrid sustainability through robust islanding detection scheme ensuring cyber-situational awareness

Along with the numerous environmental and operational benefits of renewable energy sources (RESs) integration into modern distribution networks, maintaining system security in these networks during challenging phenomena, especially unintentional islanding can still be problematic in some cases. This paper puts forward a sensitivity-based islanding detection algorithm that utilizes the transient kinetic energy of the RESs to identify the islanding condition in microgrids and also considers cyber-attacks, which may lead to operators making inappropriate operational choices. To be specific, the proposed algorithm finds a generalized index that considers simultaneously the impact of volatility of parameters during islanding and non-islanding conditions and is also robust against data integrity attacks. The generalized index, the so-called sensitivity islanding detection (SID) index, is designed based on the sensitivity of transient kinetic energy over transient influential parameters. Furthermore, a statistical index for islanding detection is introduced based on the standard variation that effectively monitors the volatilities. An unsupervised anomaly detection method that uses kernel density estimation technology and statistical calculations are proposed as a way to find cyber-attacks. Following that, an outlier detection method is used to identify anomalies. The effectiveness of the proposed algorithm is evaluated under various conditions using simulation environments.

Design techniques for improving energy performance and S-shaped characteristics of a pump-turbine with splitter blades

The development of high-head pumped-storage projects presents various opportunities and challenges. One challenge is the operational stability of pumped-storage power plants, which is closely associated with the characteristics of pump-turbines. In this study, the design and experimental verification of the hydraulic performance of a pump-turbine runner with splitter blades are investigated. The effects of several main parameters on the performance curve and S-shaped characteristics of pump-turbines in turbine mode are examined via numerical simulation. Subsequently, model tests are conducted to validate the improvements in the performance curve, including a comparison of the S-shaped characteristic curve at a constant guide vane opening and under the same initial conditions. An emergency load rejection test based on the same guide vane closing scheme is performed to verify improvements in transient pressure in the spiral case, draft tube, and rotational speed. The results confirm the enhancement in the S-shaped characteristics and transient global parameters of the splitter blade design. Furthermore, a reduction in pressure pulsation intensity in the vaneless space during off-design conditions is confirmed.

Experimental Research on Reconstruction Techniques for Instantaneous Regression Rate of Hybrid Rocket Motor with Single-Port Wagon Wheel Fuel Grain

This study investigated reconstruction techniques for building the instantaneous fuel regression rate of the hybrid rocket motor (HRM). Specifically, an experiment in a laboratory 500 N-class hybrid rocket motor with single-port wagon wheel fuel grain, operated with hydrogen peroxide (HP) and hydroxyl-terminated polybutadiene (HTPB) based fuel (including Al), was carried out. A piece of post-processing software was developed to reconstruct the instantaneous regression rate and other performance parameters of the HRM during the firing test. The results produced by the reconstruction techniques are in good agreement with experimental data obtained by traditional methods, with a maximum error of less than 5.75%. Moreover, compared with the traditional endpoint method, the reconstruction method had a significant advantage, which could ascertain the sensitivity of the regression rate to changes in the oxidizer mass flux and fit the formula of regression rate in a single firing test. Additionally, digital image processing techniques were employed to determine the axial distribution of the fuel regression rate after the test using computed tomography (CT) scanning. This served to verify the accuracy of the instantaneous reconstruction calculation. The error in the average regression rate between CT scanning and the reconstruction calculation was 1.91%, proving that the CT scanning and pixel statistic method of the calculating regression rate was practical for characterizing the axial distribution of the average regression rate during the firing test. In summary, the main objective of this study was to reconstruct the transient parameters of hybrid rocket motor with single-port wagon wheel fuel grain using reconstruction techniques, and to fit the formula of the regression rate through a single-firing test. Furthermore, this paper proposes a modified reconstruction method that is essential for investigating fuel regression rate during the firing test of HRMs.

Transient Productivity Analysis and Completion Parameter Optimization of Perforating Herringbone Wells.

Herringbone wells are of great significance in tapping the potential of remaining reservoirs, improving recovery efficiency, and reducing development costs and have been widely used in oilfields, especially offshore oilfields. Due to the complex structure of herringbone wells, there is mutual interference between wellbores during seepage, resulting in complex seepage problems, and it is difficult to analyze the productivity and evaluate the perforating effect. In this paper, considering the mutual interference between branches and perforations, a prediction model of transient productivity of perforated herringbone wells was derived based on the theory of transient seepage, and the complex structure with any number of branches, arbitrary configurations, and orientations in three-dimensional space could be considered in this model. The formation pressure in reservoir points at different production times, IPR curves, and the radial inflow of herringbone well were studied by the line-source superposition method, which directly reflected the process of productivity and pressure change, avoiding the one-sidedness caused by using a point source to replace the line source in the stability analysis. Then, through the productivity calculation of different perforation schemes, the influence curves of perforation density, perforation length, perforation phase angle, and perforation radius on unstable productivity were obtained. Orthogonal tests were performed to obtain the degree of impact of each parameter on productivity. Lastly, the selective completion perforation technology was adopted. When the shot density at the end of the wellbore was increased, the productivity of herringbone wells could be improved economically and effectively. According to the above study, a scientific and reasonable construction scheme is recommended for oil well completion construction, which provides a theoretical basis for the improvement and development of perforation completion technology.

Performance Analysis of Spectrum-Dependent Integrated Thermal–Electrical Model of a PV Module

The diurnal and seasonal changes in the solar spectrum affect the photovoltaic (PV) module performance. In this article, the transient solar spectrum was integrated with the thermal–electrical model of the PV module for precise estimation of diurnal and seasonal PV performance. The transient meteorological parameters were considered for determining the dynamic power output of the PV. The SMARTSv2.9.5, COMSOL Multiphysics, and MATLAB were used for modeling different sections and integrated throughout. The cell temperature and power output were obtained and experimentally validated for various seasons. The statistical errors, such as mean absolute error (MAE), mean relative error, and root-mean-square error (RMSE) values, and the coefficient of determination ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) value were calculated for the developed model during various seasons. The RMSE of back surface temperature and power output from monocrystalline ranges from 1.67 to 2.59 °C and 1.83 to 2.92 W, respectively, and the same for polycrystalline PV module ranges from 1.93 to 2.29 °C and 1.70 to 3.63 W, respectively. The MAE of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sc</sub> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub> ranges between 0.10 and 0.29 A and 0.41 and 0.58 V, respectively, for monocrystalline, 0.13–0.43 A and 0.39–0.52 V, respectively, for polycrystalline PV modules. The present model is a simple integration and uses basic mathematical equations and parameters to predict the PV outputs.

Comparison Performances between MABSA-PI Controller and MABSA-PD Controller for DC Motor Position System

The goal of this project is to create two different types of controllers for regulating DC motor position systems which are the MABSA-PI controller and the MABSA-PD controller. The MATLAB controllers are developed using the Simulink toolbox, while the transfer function of a DC motor is obtained from its circuit. Modified adaptive bats sonar algorithm (MABSA) will be implemented in the PI controller and PD controller as the main algorithm. MABSA is one of the swarm intelligences and is usually for an optimization problem. Next, the tuning method for the PI controller and PD controller will be the trial-and-error method. The combination graph of each controller will be shown in Simulink scope as the project is tested for various positions. The controller's ability to regulate the position of a DC motor was studied. The comparision among the system's transient response parameters, including percentage overshoot, rising time (Tr), and settling time (Ts), would be discused. Various toolbox functions available in Simulink software can be employed to repossess these parameter outcomes.

Aircraft pitch control design using LQG controller based on genetic algorithm

Designing a robust aircraft control system used to achieve a good tracking performance and stable dynamic behavior against working disturbances problem has attracted attention of control engineers. In this paper, a pitch angle control system for aircraft is designed utilizing liner quadratic Gaussian (LQG) optimal controller technique with a numerical tuning algorithm method in the longitudinal plane through cruising stage. Main design approach of LQG controller includes obtaining best weighting matrices values using trial and error method that consumes effort and takes more time, in addition, there is no guarantees to obtain optimum values for weighting matrices elements. In this research, genetic algorithm (GA) is used to optimize the state and control weighting matrices and determine best values for their elements. The proposed traditional and optimized LQG pitch controller schemes are implemented utilizing Matlab simulation tool and their performance are presented and compared based on transient and steady state performance parameters. The simulation results reveal the ability of the optimized GA_LQG controller to reject the effect of the noises in the aircraft system dynamic and achieve a good and stable tracking performance compared with that of the conventional LQG pitch control system.

Role of Dual-Contingency Management in Family-Based Obesity Therapy and the Effects of Weight Loss on Liver Transient Elastography Parameters in Youth: A Pilot Study.

The pilot study evaluated contingency management (CM) for family-based obesity therapy (FBT). The secondary outcome assessed the association of the hepatic transient electrography (TE) parameters, including the controlled attenuation parameter (CAP) and liver stiffness (LSM), and changes in liver function blood tests and BMI changes in youth involved in intensive FBT. It included youth-parent dyads from an urban pediatric center randomized to weekly behavioral therapy (BT, n= 4) who received fixed financial compensation for attendance, or BT+CM (n= 5) who received an escalating monetary reward for weight loss. At week 30, all youth and parents had weight-loss trends without significant differences between groups. While the TE measures and blood tests were normal in the youth at baseline and week 30, the CAP changes correlated with BMI changes (R2= 0.86, P< 0.001) and LSM changes with alanine aminotransferase changes (R2= 0.79, P=0.005). In conclusion, BT+CM did not significantly add to the BMI improvement seen with BT alone in youth and their parents. However, in youth with obesity and normal liver blood tests, TE may be useful for monitoring changes in fatty liver disease.

Performance Analysis and Implementation of Brushless DC Motor by PID, Fuzzy and ANIFS Controllers

Now a day’s Brushless DC (BLDC) motors are more popular because of its good electrical and mechanical property. These motors are now changing to brushed DC motors and induction motors in various applications. The main problem that occurs in the traditional PID controller is that the parameters obtained from the drive control system of the BLDC servo motor cannot produce a steady state under various operating conditions such as adjusted gain plus transient response and parameter variation, load disturbance. So a fuzzy controller provides good speed response for start-up. In this paper how the design and simulation of ANFIS controller is better for the performance of brushless DC motor (BLDC) servomotor as well as the design and implementation of ANFIS controller and its performance are compared is shown. The capability of BLDC servomotor based on Fuzzy, ANFIS and PID controller is investigated under different operating conditions. Paper represents the PID controller and fuzzy controller to demonstrate error tracking capability and usefulness of ANFIS controller in control applications. By using the PID, Fuzzy and ANFIS controller we can implement, analyze the overall performance of brushless DC motor. KEYWORDS: Proportional-Integral-Derivative (PID) controller, Brushless DC (BLDC) motor, Adaptive-Network- Based Fuzzy Inference System (ANFIS), (FLC) Fuzzy logic controller (IGBT) Insulated Gate Bipolar Transistor.

Validation of the utility of Agile scores to identify advanced fibrosis and cirrhosis in Japanese patients with nonalcoholic fatty liver disease.

Agile 3+ and Agile 4 scores, based on liver stiffness measurement (LSM) by transient elastography and clinical parameters, were recently reported to be effective in identifying advanced fibrosis and cirrhosis in nonalcoholic fatty liver disease (NAFLD). This study aimed to validate the utility of these scores in Japanese patients with NAFLD. Six hundred forty-one patients with biopsy-proven NAFLD were analyzed. The severity of liver fibrosis was pathologically evaluated by one expert pathologist. The LSM, age, sex, diabetes status, platelet count, and aspartate aminotransferase and alanine aminotransferase levels were used to calculate Agile 3+ scores, and the parameters above excluding age were used for Agile 4 scores. The diagnostic performance of the two scores was evaluated using receiver operating characteristic (ROC) curve analysis. Sensitivity, specificity, and predictive values of the original low cut-off (for rule-out) value and high cut-off (for rule-in) value were tested. For diagnosis of fibrosis stage ≥3, the area under the ROC (AUROC) was 0.886, and the sensitivity of the low cut-off value and the specificity of the high cut-off value were 95.3% and 73.4%, respectively. For diagnosis of fibrosis stage 4, AUROC, the sensitivity of the low cut-off value, and the specificity of the high cut-off value were 0.930, 100%, and 86.5%, respectively. Both scores had higher diagnostic performance than the FIB-4 index and the enhanced liver fibrosis score. Agile 3+ and Agile 4 are reliable noninvasive tests to identify advanced fibrosis and cirrhosis in Japanese NAFLD patients with adequate diagnostic performance.

A Method for Calibrating the Transient Storage Model from the Early and Late-Time Behavior of Breakthrough Curves

Solute transport in rivers is controlled by mixing processes that occur over a wide spectrum of spatial and temporal scales. Deviations from the classic advection–dispersion model observed in tracer test studies are known to be generated by the temporary trapping of solutes in storage zones where velocities and mixing rates are relatively small. In this work, the relation between the early and late-time behavior of solute breakthrough curves (BTCs) and the key parameters of the Transient Storage Model (TSM) is analyzed using non-asymptotic approximations of the model equations. Two main slopes are identified corresponding to the rising and decreasing limbs of the BTCs which are linked by specific relationships to transport and storage parameters. The validity of the proposed approximations is demonstrated with both synthetic and experimental data. Consistent with the TSM assumptions, the range of validity of the proposed approximations represents the limit of separability between surface dispersion and transient storage and can be expressed as a function of a nondimensional parameter. The results of this work can help environmental scientists identify solute transport and transient storage parameters and support the design of enhanced field tracer experiments.

Experimental study on the electrohydrodynamic deformation of droplets in a combined DC electric field and shear flow field.

A visualization experiment was conducted to investigate the electrohydrodynamic deformation of droplets in a combined DC electric field and shear flow field. Detailed experimental data on both the transient and steady droplet deformation parameters (D) and orientations (ϕd ) are provided at R > S and R < S (R: conductivity ratio; S: permittivity ratio) under different electric field and shear flow field combinations. The internal flow characteristics of the deformed droplet were also examined via the digital particle image velocimetry (DPIV) method. Due to the competition of the extensional component (EC) and the rotational component (RC) of these two fields on the droplet, the response of ϕd is faster than that of D when an electric field is combined with a shear flow. Additionally, under the competition of the EC and RC at R > S and R < S, the steady-state D and ϕd values exhibit distinct variations. In particular, surface charge convection plays a non-negligible role in enhancing and reducing droplet deformation at R > S and R < S, respectively. In addition, an asymmetric vortex forms inside the deformed droplet in the combined fields, and its velocity is lower under R > S and higher under R < S than in pure shear flow. The available prediction models use the experimental data to predict D, and a modified prediction model is proposed for improving the prediction accuracy of ϕd .

The effect of different direct antivirals on hepatic steatosis in nondiabetic and naïve hepatitis C-infected Egyptian patients

BackgroundHepatitis C is associated with metabolic effects and fatty liver disease. The effect of different direct antivirals on the liver steatosis, and the metabolic profile, still needs to be established. The aim of this study is to determine the effect of achieving the sustained virological response after 12 weeks (SVR-12 weeks) with different combinations of direct antiviral drugs, on the hepatic steatosis, and fibrosis presented by laboratory and transient elastography parameters. Our study population is nondiabetic, chronically infected HCV Egyptian patients and naïve to any form of HCV treatment.MethodsThis cohort study was carried on 100 nondiabetic HCV treatment-naïve patients attending the Hepatology Clinic, in the Gastroenterology and Hepatology Department, Ain Shams University, and Kobry El Koba Military Hospital. The patients were divided into four groups according to their treatment regimens as follows: group A: 25 patients who received sofosbuvir (400 mg) and daclatasvir (60 mg) daily for 12 weeks; group B: 25 patients who received sofosbuvir (400 mg) and ledipasvir (90 mg) daily for 12 weeks; group C: 25 patients who received ombitasvir (12.5 mg), paritaprevir (75 mg), and ritonavir (50 mg) daily for 12 weeks; and group D: 25 patients who received sofosbuvir (400 mg) and simeprevir (150 mg) daily for 12 weeks. All patients were subjected to the following investigations: HCV quantitative PCR before and after 12 weeks of treatment, clinical and laboratory metabolic evaluation including alfa-fetoprotein level, thyroid profile assessment, ferritin level, pelvi-abdominal ultrasound, and FibroScan examination.ResultsAll patients achieved SVR after 12 weeks. FibroScan median decreased (P < 0.001) from 19.29 ± 6.97 kPa at baseline to 14.15 ± 6.48 kPa at SVR12. NAFLD score median increased from 1.88 (1.49–2.22) at baseline to 2.01 (1.61–2.33) after 12 weeks of treatment. The highest level of NAFLD score was in group C, and the lowest was in group B. The BMI mean decreased from 28.31 ± 1.53 at baseline to 28.07 ± 1.52 at SVR12. HbA1C level mean decreased from 5.73 ± 0.23 at baseline to 5.40 ± 0.24 at SVR12. In addition, liver enzymes, cholesterol, triglycerides, APRI score (AST-platelet ratio index), and HBA1C decreased after 12-week treatment with a statistically significant difference, while the mean LDL increased after 12 weeks of treatment.ConclusionsDAAs affect the metabolic profile of the treated patients. There is a noticed improvement in the FibroScan, NAFLD score, and lipid profile after achieving the SVR-12 weeks. However, LDL is increased after viral cure, mostly due to viral-host molecular interaction.

Pharmaco-Toxicological Effects of Atypical Synthetic Cathinone Mephtetramine (MTTA) in Mice: Possible Reasons for Its Brief Appearance over NPSs Scene.

Over the last year, NPSs have been steadily on the rise in the illicit drug market. Among these, synthetic cathinones seem to become increasingly popular among young adults, mainly because of their ability to replicate the effects of traditional psychostimulant drugs, such as cocaine, MDMA and amphetamines. However, scarce data are available about the in vivo pharmaco-toxicology of these new substances. To this end, this study focused on evaluation of effects induced by repeated administration of mephtetramine (MTTA 0.1-30 mg/kg i.p.) in mice. This atypical cathinone highlighted a sensorial (inhibition of visual and acoustic reflexes) and transient physiological parameter (decrease in breath rate and temperature) change in mice. Regarding motor activity, both a dose-dependent increase (accelerod test) and biphasic effect (drag and mobility time test) have been shown. In addition, blood and urine samples have been analysed to enrich the experimental featuring of the present study with reference to evaluation of potential toxicity related to consumption of MTTA. The latter analysis has particularly revealed important changes in blood cells count and blood and urine physicochemical profile after repeated treatment with this atypical cathinone. Moreover, MTTA induced histological changes in heart, kidney and liver samples, emphasizing its potential toxicity.

Modeling of sodium-cooled fast reactor core – A sensitivity study on number of core channels and axial meshes

System thermal–hydraulic codes are used in the dynamics analysis of sodium-cooled fast reactors (SFRs). In such simulations, the accuracy of the reactor core model is very important to establish plant safety. Coupled physical phenomena, namely, heat transfer, fluid dynamics, and neutronics, need to be simulated in the core. Due to the complexity, a simplified core modeling approach has been traditionally followed in system dynamics codes. Firstly, steady-state core neutronics calculations are carried out using a 2D axisymmetric model to obtain perturbation worth and power distributions. Later, this data is mapped to several core channels (usually 10 to 20), each representing a set of fuel subassemblies (SAs) for thermal-hydraulics calculations.In this paper, a more sophisticated core modeling approach has been followed to understand the importance of such an exercise. A 3D neutronics model was used to obtain subassembly-wise perturbation worths and power distributions. For thermal-hydraulics calculations, the number of core channels was increased with the idea of one subassembly per channel. The number of axial meshes in each channel was also increased. The traditional and new modeling approaches were used to simulate the benchmark problem of FFTF LOFWOS test#13 for comparison. Steady-state parameters from both the new and the old models were comparable. Notably, there was a peaking of the axial power profile in the new model compared to the old model, which resulted in slightly higher peak fuel temperatures in the new model. However, the difference in the evolution of transient parameters between the two models was insignificant, and both models compared reasonably well with the benchmark data.

A dual-mode novel Parabolic Trough Collector for process heating applications in small scale industries—Thermo-hydraulic and performance investigation

Only a few industries worldwide use solar heat for industrial processes, despite the fact that it is a proven and cleaner solution. More over, Small-scale industries need hot water and low-enthalpy steam, but such systems receive scant attention due to the active nature of Parabolic Trough Collectors as well as the use of less efficient flat plate technology in this temperature range. This delineate the opportunity for research focus in efficient passive technologies especially in low temperature range. In this regard a novel dual mode Parabolic Trough Collector based on an Open Natural Circulation Loop (PTC-ONCL) is proposed here. Focus of this work is to assess the proposed system’s suitability for process heating applications requiring hot water/low enthalpy steam, especially in rural areas. Experiments are conducted on an in-house prototype. A novel methodology for correlating actual solar data to the input heat load for the in-house test facility is developed. Five representative solar days are considered for individual tests. Startup, transient, and efficiency parameters are evaluated. Productivity, industrial viability, and environmental impact are also accessed. Throughout the test, the loop maintained a stable flow, where the start-up oscillations, thermal oscillations and type-I instabilities are observed. The system operates at an unprecedented efficiency of 72 ± 4% in hot water mode and 70 ± 5% in Steam generation over a 7 h period. The economic analysis shows an ambitious Levelized Cost of Heat of 2.8 cents/kWh, with a payback period of 3.21 years. Moreover environmental study shows its huge potential in reducing the CO 2 emissions. A dimensionless index is proposed to represent the solar day and is correlated to predict the average water temperature and steam generated with RMSE values of 0.98 °C and 0.125 kg respectively. The solar day index comprehends the total irradiation, wind velocity and the ambient temperature. The proposed PTC-ONCL system is capable of producing an annual average of 8.67 kgday −1 and/or 150 L of hot water at an average temperature of 89.07 °C. The results, and the system’s low cost and near-maintenance-free nature demonstrates its capability in the desired application, both technologically and economically. • A passive Parabolic Trough Collector based on an Open Natural Circulation Loop for process heat at low temperature. • New methodology correlates actual solar data to input for an in-house test facility. • Generates 8.67 kg of steam/ hot water at 89 °C on a yearly average with 65% efficiency. • Levelized Cost of Heat of 2.8 cent/kWh & 3.2 years of payback period found promising. • Dimensionless solar day index includes combines irradiation and ambient condition.