Actual Mass Flow Rate Research Articles

Modeling the Discharge Rate of a Screw Conveyor Considering Hopper–Conveyor Coupling Parameters

Developing a flow rate model for the screw feeder and optimizing discharge performance are crucial for achieving automated intelligent precision feeding. This study constructs a mass flow rate model for screw conveyors, considering the coupled structural parameters of the hopper and screw conveyor. The model is developed using single-factor tests and central composite design (CCD) response surface tests and is validated through actual discharge tests. Results indicate that the discharge rate in the hopper–screw conveyor system is primarily influenced by the screw conveyor itself. Among the structural parameters, the hopper inclination angle and the hopper discharge opening length significantly affect the filling coefficient. Validation tests show an average error of 6.8% between the predicted and simulated mass flow rates and 5.0% with the actual mass flow rate, demonstrating the model’s high precision and accuracy.

Fluid–Thermal–Structure Interaction of Hypersonic Inlets Under Different Aspect Ratios

It is crucial to consider the fluid–thermal–structural interaction (FTSI) in designing the scramjet inlet for sustained hypersonic flight. To understand the aerothermal and aeroelastic responses of the planar hypersonic inlets under different flight Mach numbers and aspect ratios, a three-dimensional FTSI framework was developed and validated. After that, the FTSI characteristics under different flight Mach numbers and aspect ratios were investigated. The result reveals that the most obvious horizontal displacement happens at the cowl lip leading edge, whereas the maximum vertical displacement takes place at the compression-ramp leading edge. The FTSI improves the capture area and generates an additional compression angle due to the different thermal expansions between the windward and leeward panels. The thermal expansion in the spanwise direction causes the cowl lip to hump into an arc, and the maximum height happens at the midplane. The effects of FTSI on the inlet flowfield, the mass flow rate, and the total pressure ratio under different flight Mach numbers and aspect ratios were obtained. Overall, the FTSI can improve the contraction ratio, the actual mass flow rate, and the pressure ratio while causing the total pressure ratio to decrease by up to 14.64%.

Solar Field Output Temperature Optimization Using a MILP Algorithm and a 0D Model in the Case of a Hybrid Concentrated Solar Thermal Power Plant for SHIP Applications

Using solar power for industrial process heat is an increasing trend to fight against climate change thanks to renewable heat. Process heat demand and solar flux can both present intermittency issues in industrial systems, therefore solar systems with storage introduce a degree of freedom on which optimization, on a mathematical basis, can be performed. As the efficiency of solar thermal receivers varies as a function of temperature and solar flux, it seems natural to consider an optimization on the operating temperature of the solar field. In this paper, a Mixed Integer Linear Programming (MILP) algorithm is developed to optimize the operating temperature in a system consisting of a concentrated solar thermal field with storage, hybridized with a boiler. The MILP algorithm optimizes the control trajectory on a time horizon of 48 h in order to minimize boiler use. Objective function corresponds to the boiler use, for completion of the heat from the solar field, whereas the linear constraints are a simplified representation of the system. The solar field mass flow rate is the optimization variable which is directly linked to the outlet temperature of the solar field. The control trajectory consists of the solar field mass flow rate and outlet temperature, along with the auxiliary mass flow rate going directly to the boiler. The control trajectory is then injected in a 0D model of the plant which performs more detailed calculations. For the purpose of the study, a Linear Fresnel system is investigated, with generic heat demand curves and constant temperature demand. The value of the developed algorithm is compared with two other control approaches: one operating at the nominal solar field output temperature, and the other one operating at the actual demand mass flow rate. Finally, a case study and a sensitivity analysis are presented. The MILP’s control shows to be more performant, up to a relative increase of the annual solar fraction of 4% at 350 °C process temperature. Novelty of this work resides in the MILP optimization of temperature levels presenting high non-linearities, applied to a solar thermal system with storage for process heat applications.

Thermal Method for Non-Destructive Control of Actual Coolant Mass Flow through a Heating Device

The studies show that expenses for heating buildings and structures account for more than 60% of total utility costs in the Russian Federation. Therefore, the issues on energy and resource conservation and improving the energy efficiency of construction projects for various purposes are relevant and priority. Infrared thermography is actively used during examination of thermomechanical equipment, building structures, external and internal engineering systems and their elements. Heat monitoring makes it possible to avoid significant costs for dismantling of controlled objects and to localize the thermal defects found during the inspection stage, thereby reducing costs of repair works. The article considers and analyzes the existing options for the quantitative analysis of thermograms. The authors propose a new method for quantitative processing of thermograms, aimed at assessing the operation of heating devices in heating systems of buildings and structures. The essence of thermal non-destructive testing technique is to determine the actual mass flow rate of coolant through the heating device.

Signal Analysis of Supersonic Vapor Condensation in Nozzle Sensor Using Distributed Transient Pressure Probes

The amplitude–frequency characteristics of self-excited oscillating pressure in nozzle condensation dominate the actual flow field and mass flow rate, which affect the measurement accuracy of the sonic nozzle for the moist gas. In order to estimate this effect and improve the measurement accuracy, the complex supersonic vapor nozzle condensation with different nozzle geometries was investigated. First, the raw signals of the time-averaged and transient oscillating pressure during the condensation occurs in the nozzle were acquired, by using a multiparameter adjustable humidification apparatus, two nozzle sensors with distributed pressure probes and a 10th order low-pass hardware filter. Then, these raw signals were decomposed and reconstructed to further improve the filtering result, by using discrete wavelet transforms with the Db5 wavelet bases. Finally, the accurate amplitude–frequency characteristics of the transient pressure signals were extracted and analyzed by fast Fourier transform and the ratio correction method. It found that the experimental frequencies are mainly dependent on the curvature of nozzle wall and mass fraction of water vapor, which is also compared with a semiempirical formula derived from the experiments of 2-D symmetric rectangular nozzle. The results showed that this formula has a significant deviation from the experimental results of 3-D toroidal nozzles, which needs to be investigated further. All the research is contributed to further analyze the effect of condensation on the actual mass flow of the sonic nozzle.

A novel quasi-one-dimensional model for performance estimation of a Vaporizing Liquid Microthruster

The present work aims to propose a novel quasi-one-dimensional model for the performance estimation of a Vaporizing Liquid Microthruster (VLM). The analytical model was applied to the analysis of a MEMS-based VLM composed of a rectangular inlet chamber, a set of parallel microchannels as heating chamber, and a planar convergent–divergent micronozzle. It combines a steady-state boiling model for the analysis of the heater with a real nozzle flow model for the evaluation of actual thrust force and specific impulse, based on iterative procedure aiming at the convergence of the actual mass flow rate and the heat flux. For the purpose, a set of semi-empirical formulas found among both theoretical and experimental scientific works have been introduced for the estimation of the critical heat flux condition and the local heat transfer coefficient. In addition, the real nozzle flow model predicts the performance and the viscous losses due to the boundary layer growth inside the micronozzle. The last ones are estimated by introducing analytical expressions for the discharge coefficient and the Isp-efficiency into the isentropic nozzle flow theory. The resulting performance predictions of the 1D model referred to the on-design operating conditions. They well agreed with the experimental data, with a maximum estimated error of 7.3% on the thrust and the specific impulse. Furthermore, the analytical model of the micronozzle predicted a reduction of the mass flow rate up to about 8%, as well as thrust losses up to 15% due to the contraction of the cross sectional area.In addition, 2D and 3D computational fluid dynamics (CFD) simulations were performed in order to enforce the analysis of the viscous effects. Predictions of 2D computations overestimated the performances of the microthruster with respect to experiments, up to about 19% of the thrust and 20% of the specific impulse. On the other hand, the 3D predicted thrust approached to the experimental one with an error of about 9.2% below. In addition, a severe reduction of jet thrust in favor of the pressure thrust was observed at the nozzle exit. Furthermore, 3D computations pointed out the influence of the micronozzle depth on the boundary layer growth and the viscous losses. In particular, they revealed the establishment of the nozzle blockage and the thermal chocking of the supersonic flow owing to the subsequent viscous heating.

Real-time acoustic emission monitoring of powder mass flow rate for directed energy deposition

In order to ensure a reliable and repeatable additive manufacturing process, the material delivery rate in the directed energy deposition (DED) process requires in situ monitoring and control. This paper demonstrates acoustic emission (AE) sensing as a method of monitoring the flow of powder feedstock in a powder fed DED process. With minimal calibration, this signal closely correlates to the actual mass flow rate. This article describes the fabricated mass flow monitoring system, documents various conditions in which the actual flow rate deviates from its set value, and details situations that highlight the system’s utility. While AE mass flow monitoring is not free of concerns, its features make it an attractive measurement technique in the powder-fed DED process. The work presented here highlights the results obtained and illustrates that accurate monitoring of powder flow in real-time regardless of environmental conditions within the build chamber is possible.

Development of a numerical correlation for the discharge coefficient of round inclined holes with low crossflow

Abstract The estimation of the discharge coefficient is of paramount importance in gas turbine design as this parameter affects the actual mass flow rate through secondary air and cooling systems. The lack of confidence in the estimation of its value may entail a reduction in the engine performance as well as lifespan. The scope of this work is therefore still an object of study in the scientific community, mostly due to the complexity and the variety of phenomena involved. In an effort to provide a general characterization of the aerodynamic losses across round orifices, an extended numerical campaign was carried out to develop a correlation for the discharge coefficient. The investigation was focused on round, inclined holes at isothermal conditions, with limited crossflow on both mainstream and coolant sides. Exploiting CFD simulations validated against a literature test case, a Design of Experiments (DoE) was performed to assess the influence of length-to-diameter ratio (L/d), inclination angle with respect to the crossflow direction (α) and pressure ratio (β). The large amount of data obtained were then correlated in order to provide an expression capable of predicting the discharge coefficient. The correlation is valid for round holes ( α = 20 ∘ − 90 ∘ , L / d = 1 − 10 , β = 1.01 − 2.0 ) with low crossflow on both mainstream and coolant sides ( M a m = M a c = 0.02 ). allowing to reproduce the CFD data set with a mean absolute error of 3.44% and a standard deviation of 1.81%.

Gasification of high-ash Indian coal in bubbling fluidized bed using air and steam – An experimental study

In this experimental study, gasification characteristics of Indian coals having high ash content (>35%) in a bubbling fluidized bed reactor, using air and steam as the gasification agents under atmospheric pressure, are presented. The thermal power output of the gasification device has been varied in the range of 80–100kW. The ratio of the actual mass flow rate of air supplied to the stoichiometric air mass flow rate (required for complete combustion) has been varied in the range of 0.25–0.35. The ratio of mass flow rate of steam to that of coal has been varied from 0.15 to 0.25. Effects of air and steam flow rates on the calorific value of product gas, carbon conversion and cold gas efficiency have been studied in detail. For high-ash Indian coals, supply of steam produces positive effect as all the metrics such as calorific value of product gas, carbon conversion and cold gas efficiency increases with increase in the steam supply rate.

Forecasting the Time Evolution of the Oil Price During Months of Negative Inflation Rate

Mass conservation equation is employed to study the time evolution of the mass of oil in a reservoir, according to the actual mass flow rate of extraction. It is also possible to define the critical mass flow rate of extraction, which is the value exhausting the reservoir in an infinite time. The evolution with time of the price of the resources extracted and sold to the market is investigated in case of no-accumulation and no-depletion of the resources, i.e., when the resources are extracted and sold to the market at the same mass flow rate. The total energy conservation equation is transformed into a money or capital per time conservation equation, which allows to study the price evolution with time, which is dependent on the following parameters. The price evolution with time of the extracted resource is dependent on the parameter PIFE, “Price-Increase Factor of Extracted resource,” which is the difference between the basic interest rate of the capital, e.g., the inflation rate, and the mass flow rate of extraction. The price evolution with time of the sold resource is dependent on the parameter PIFS, “Price-Increase Factor of Sold resource,” which is the difference between the interest rate of the capital, e.g., discount or prime rate, and the mass flow rate of extraction. The parameter CIPS, “Critical Initial Price of Sold resource,” depends on the initial price of the extracted resource, on the interest rate of nonextracted resource, and on the difference between PIFS and PIFE. The parameter CIPES, “Critical Initial Price Extreme of Sold resource,” depends on the initial price of the extracted resource, on the interest rate of nonextracted resource, and PIFS. The time evolution of the oil price during the 8 months of 2009, when the inflation rate was negative, and following the economic crisis of 2008, is investigated introducing a new category of cases, i.e., the negative inflation rate one. The paper presents and discusses the results of the forecasting for different values of the interest rate of the capital, i.e., prime and discount rate, with the conclusion that the present theory can forecast the evolution of the oil price with a reasonable confidence using the prime and the discount rates as extreme limits.

Numerical Study on Three-Dimensional Wall Effects of Flat Micro Nozzle

The FLUENT6.1 software is applied to simulate the supersonic flow in micro convergent-divergent nozzle which is fabricated from flat silicon wafers. The simulation is complemented by parallel computing steady 2-D and 3-D Navier-stokes equations to study the three-dimensional wall effects on temperature and velocity inside the micro nozzle. Also the performances of fluent mass coefficients and thrust force efficiencies are studied. It is observed by the study that three-dimensional wall effects are not negligible in flat micro nozzle. The velocity of fluid in three-dimensional nozzle is less than the corresponding velocity of fluid in two-dimensional nozzle significantly, while the temperature of fluid in three-dimensional nozzle is much higher than the corresponding temperature of fluid in two-dimensional nozzle. The mass flow rate and thrust at the exit of 2-D nozzle are greater than the corresponding mass flow rate and thrust at the exit of three-dimensional. With the throat Renaults being increased, the corresponding differences between two-dimensional numerical results and three-dimensional numerical results decreased accordingly. Two-dimensional numerical results can not correctly predict the actual mass flow rate and thrust at the exit of micro nozzle.

Experimental and numerical investigation of tar destruction under partial oxidation environment

Tar in biomass product gas is a major problem because it reduces the reliability of the equipment and enhances pollutant emission. Partial oxidation is effective for reducing tar inside gasifiers. In order to predict tar reduction with partial oxidation technology, knowledge of the fate of tar during partial oxidation process is paramount. A continuous reactor was developed for tar destruction experiment under partial oxidation environment. Tar components and non-condensable gasses were measured and analyzed. Results show that the defined “primary tar” contents share about 60% of the total tar amounts. Phenolics prevail under initial reaction, but it is easy to form PAHs (polycyclic aromatic hydrocarbons) by polymerization reactions under certain ER (actual mass flow rate of oxygen/oxygen required for complete oxidation of biomass feed stock). This process results in an increase of tertiary tar. Hydrogen's evolution curve shows a steep rise with ER, which could be an indicator for the crack of secondary tar. A model was developed for describing partial oxidation of tar. Phenol, toluene, benzene and naphthalene were chosen as model compounds. Fluid flow, chemical mechanism and heat transfer are considered in the model. The calculated total tar amounts are in qualitative agreement with experimental results.

Extended Insight into the Metastable Liquid Region Behavior in an Adiabatic Capillary Tube

Over the past decade, the development of theoretical models used to simulate capillary tube performance has steadily progressed. Currently, the major obstacle to improving performance model accuracy is the inability to accurately predict the onset of vaporization (flash point) and thereby the metastable liquid region length. It has been demonstrated that neglecting this region's effect on the overall flow resistance can lead to an underprediction by 5 to 25% of the actual mass flow rate through a capillary tube. Before an accurate metastable liquid region model can be developed, however, a more thorough understanding of the region behavior is necessary. In response, an experimental study has been completed with R-134a using a single adiabatic capillary tube. Testing was undertaken to determine if the metastable liquid region effect on steady-state mass flow rate measurements was repeatable and dependent on controllable test parameters, as had been suggested in a recent study. The experimental parameters were: steady-state inlet subcool level (three levels), the direction of approach to the steady-state inlet temperature (increasing or decreasing temperature), and the forced inlet temperature response rate used in attaining the steady-state flow condition. The resulting general data trend demonstrated increasing scatter in repeated flow rate measurements as the inlet subcool level decreased. Further, there appeared to be some dependence of the flow rate data on the experimental procedure used in setting the inlet condition. However, even under controlled test conditions the dependence was not always repeatable. Using a theoretical flow model, it was shown that most of the data scatter among repeated measurements was caused by variation in the flash point location and thereby the metastable liquid region length. These results precipitated a second experimental phase designed to determine if the flash point location could be controlled. If so, the scatter in measured mass flow rate data for a common inlet condition would be reduced. Two modifications were made to the capillary tube. First, a thin wire was run through its entire length and the original test matrix repeated. The overall measured flow rate levels were lower due to the decrease in flow area caused by the wire. But in comparison to the measurements without the wire, the proportional range of data scatter was cut in half. The second modification was made by drilling five 0.020 in. (0.51 mm) diameter holes through the tube wall, which were spaced at 5 in. (127 mm) toward the end of the tube. Each hole was sealed along the outer tube surface, thus creating a series of wall cavities acting as potential nucleation sites. The overall measured flow rate levels were reduced by roughly 13% in comparison to the original unmodified tube. But more interestingly, the range of data scatter was reduced by nearly an order of magnitude. In conclusion, it was proven that the data scatter in repeated measurements of mass flow rate was caused by variation in the flash point location. It was then demonstrated that the variation in the flash point location could be controlled. Once controlled, an accurate prediction of the metastable liquid region length is potentially possible, which will in turn improve the accuracy of theoretical flow models used to simulate capillary tube performance.

Velocity and Mass Flow Rate Profiles of Particle Conveying Using Electrical Charge Tomography

This paper describes measurements made on a gravity drop conveyor using two arrays of axially spaced electrodynamic sensors to measure axial velocities close to the wall of the conveyor and velocity profiles of both flowing sand and plastic beads. The level of correlation obtained using pixels is investigated. The velocity profile is combined with a tomographic concentration profile to estimate the mass flow profile, which is summed over the measurement cross-section to estimate the mass flow rate. A calibration of tomographically determined mass flow rate versus actual mass flow rate is presented.

Velocity and mass flow rate profiles of dry powders in a gravity drop conveyor using an electrodynamic tomography system

This paper describes measurements made on a gravity drop conveyor using two arrays of axially spaced electrodynamic sensors to measure axial velocities close to the wall of the conveyor and velocity profiles both of flowing sand and of plastic beads. The level of correlation obtained using pixels is investigated. The velocity profile is combined with a tomographic concentration profile to estimate the mass flow profile, which is summed over the measurement cross section to estimate the mass flow rate. A calibration of the tomographically determined mass flow rate versus the actual mass flow rate is presented.

Development of the dry sand/rubber wheel abrasion test

A rubber wheel abrasion tester with some advantages over the design described in ASTM G65 has been designed and characterised. In the new design the specimen was held horizontally. It was therefore possible to determine the actual mass flow rate of abrasive abrading the specimen and consequently the number of particles in the contact zone and the load carried by each particle. The abrasive feed system was designed to improve control over the conditions in the contact region. The performance of the apparatus was evaluated in tests on low carbon (AISI 1020) steel, with wheels made from cast polyurethane and chlorobutyl rubber. The influences of load, sliding speed and rubber hardness were investigated. Temperature rises of wheel, specimen and sand, and the friction force were measured; the main mechanism of heat dissipation was through the continual flow of fresh abrasive past the specimen.

Effect of the degree of aeration on the error of flowmeter converging devices

1. It has been shown that when measuring flow rates of incompressible liquids using standard diaphragms, considerable errors may arise due to the presence of gas in the liquid (even for small gas contents). In the experiments when measuring the flow rate of water aerated with a gas content of 5% by volume at the input to the diaphragm, the errors can be as much as 2.2% of the actual mass flow rate of the liquid phase. 2. The errors in measuring the flow rate which were observed for gas contents from 0.5 to 8.0% and ratios of the absolute pressure at the exit from the converging device to the absolute pressure at the entrance of greater than 0.8 have an upper limit set by the limit of the dependence obtained for the flow of a uniform mixture, and a lower limit set by the individual flow of liquid and gas phases ignoring compressibility.