Flow Features Analysis of Throttle Notches of Proportional Direct Valve

2011 ◽  
Vol 189-193 ◽  
pp. 2285-2288
Author(s):  
Wen Hua Jia ◽  
Chen Bo Yin ◽  
Guo Jin Jiang
Keyword(s):  
Fluid Flow ◽  
Dynamic Behavior ◽  
Flow Rate ◽  
Discharge Coefficient ◽  
3D Models ◽  
Operating Conditions ◽  
Flow Models ◽  
Flow Features ◽  
Rate Discharge ◽  
Spool Valve

Flow features, specially, flow rate, discharge coefficient and efflux angle under different operating conditions are numerically simulated, and the effects of shapes and the number of notches on them are analyzed. To simulate flow features, 3D models are developed as commercially available fluid flow models. Most construction machineries in different conditions require different actions. Thus, in order to be capable of different actions and exhibit good dynamic behavior, flow features should be achieved in designing an optimized proportional directional spool valve.

Experimental Characterization and Gray-Box Modeling of Spool-Type Automotive Variable-Force-Solenoid Valves With Circular Flow Ports and Notches

2005 ◽  
Vol 128 (3) ◽  
pp. 636-654 ◽  
Author(s):  
M. Cao ◽  
K. W. Wang ◽  
L. DeVries ◽  
Y. Fujii ◽  
W. E. Tobler ◽  
...  
Keyword(s):  
Flow Rate ◽  
Discharge Coefficient ◽  
Automatic Transmission ◽  
Operating Conditions ◽  
Neural Network Modeling ◽  
Fluid Force ◽  
Physical Knowledge ◽  
Fluid Field ◽  
Variable Force ◽  
Hydraulic Valve

In automatic transmission design, electronic control techniques have been adopted through proportional variable-force-solenoid valves, which typically consist of spool-type valves (Christenson, W. A., 2000, SAE Technical Paper Series, 2000-01-0116). This paper presents an experimental investigation and neural network modeling of the fluid force and flow rate for a spool-type hydraulic valve with symmetrically distributed circular ports. Through extensive data analysis, general trends of fluid force and flow rate are derived as functions of pressure drop and valve opening. To further reveal the insights of the spool valve fluid field, equivalent jet angle and discharge coefficient are calculated from the measurements, based on the lumped parameter models. By incorporating physical knowledge with nondimensional artificial neural networks (NDANN), gray-box NDANN-based hydraulic valve system models are also developed through the use of equivalent jet angle and discharge coefficient. The gray-box NDANN models calculate fluid force and flow rate as well as the intermediate variables with useful design implications. The network training and testing demonstrate that the gray-box NDANN fluid field estimators can accurately capture the relationship between the key geometry parameters and discharge coefficient/jet angle. The gray-box NDANN maintains the nondimensional network configuration, and thus possesses good scalability with respect to the geometry parameters and key operating conditions. All of these features make the gray-box NDANN fluid field estimator a valuable tool for hydraulic system design.

Analytical Dynamic Modeling of Line-Focus Solar Collectors

1981 ◽  
Vol 103 (3) ◽  
pp. 244-250 ◽  
Author(s):  
J. D. Wright
Keyword(s):  
Fluid Flow ◽  
Flow Rate ◽  
Industrial Process ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Fluid Flow Rate ◽  
Digital Controllers ◽  
Dynamics Models ◽  
Line Focus

Solar thermal electric power and industrial process heat systems may require a constant outlet temperature from the collector field. This constant temperature is most efficiently maintained by adjusting the circulating fluid flow rate. Successful tuning of analog or digital controllers requires a knowledge of system dynamics. Models relating deviations in outlet temperature to changes in inlet temperature, insolation, and fluid flow rate illustrate the basic responses and the distributed-parameter nature of line-focus collectors. When plotted in dimensionless form, the frequency response of a given collector is essentially independent of the operating conditions, suggesting that feedback controller settings are directly related to such easily determined quantities as collector gain and fluid residence time.

scholarly journals On morphology and amplitude of 2D and 3D thermal anomalies induced by buoyancy-driven flow within and around fault zones

2020 ◽  
Author(s):  
Laurent Guillou-Frottier ◽  
Hugo Duwiquet ◽  
Gaëtan Launay ◽  
Audrey Taillefer ◽  
Vincent Roche ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Fault Zone ◽  
3D Models ◽  
Fault Zones ◽  
Rock Properties ◽  
Thermal Anomalies ◽  
Flow Models ◽  
Temperature Anomalies ◽  
Vertical Fault ◽  
Dip Angle

Abstract. In the first kilometres of the subsurface, temperature anomalies due to heat conduction processes rarely exceed 20–30 °C. When fault zones are sufficiently permeable, fluid flow may lead to thermal anomalies much higher, as evidenced by the emergence of thermal springs or by fault-related geothermal reservoirs. Hydrothermal convection triggered by buoyancy effects creates thermal anomalies whose morphology and amplitude are not well known, especially when depth- and time-dependent permeability are considered. Exploitation of shallow thermal anomalies for heat and power production partly depends on the volume and on the temperature of the hydrothermal reservoir. This study presents a non-exhaustive numerical investigation of fluid flow models within and around simplified fault zones, where realistic fluid and rock properties are accounted for, as well as appropriate boundary conditions. 2D simplified models point out relevant physical mechanisms for geological problems, such as thermal inheritance or splitting plumes showing a pulsating behaviour. When permeability is increased, the classic finger-like upwellings evolve towards a bulb-like geometry, resulting in a large volume of hot fluid at shallow depth. In the simplified 3D models, where fault zone dip angle and fault zone thickness are varied, the anomalously hot reservoir exhibits a kilometre-sized hot air balloon morphology, or, when permeability is depth-dependent, a funnel-shape geometry. For thick faults, the number of thermal anomalies increases but not the amplitude. The largest amplitude (up to 80–90 °C) is obtained for vertical fault zones. At the top of a vertical, 100 m wide, fault zone, temperature anomalies greater than 30 °C may extend laterally over more than 1 km from the fault boundary. These preliminary results should motivate further geothermal investigations of more elaborated models where topography and fault intersections would be accounted for.

Rack-Level Thermosyphon Cooling and Vapor-Compression Driven Heat Recovery: Compressor Model

2021 ◽  
Author(s):  
Rehan Khalid ◽  
Raffaele Luca Amalfi ◽  
Aaron P. Wemhoff
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Recovery ◽  
Operating Conditions ◽  
System Level ◽  
Scroll Compressor ◽  
Discharge Temperature ◽  
Shaft Power ◽  
Rate Discharge

Abstract This paper introduces a novel thermal management solution coupling in-rack cooling and heat recovery system. System-level modeling capabilities are the key to design and analyze thermal performance for different applications. In this study, a semi-empirical model for a hermetically sealed scroll compressor is developed and applied to different scroll geometries. The model parameters are tuned and validated such that the model is applicable to a variety of working fluids. The identified parameters are split into two groups: one group is dependent on the compressor geometry and independent of working fluid, whereas the other group is fluid dependent. By modifying the fluid-dependent parameters using the specific heat ratios of two refrigerants, the model shows promise in predicting the refrigerant mass flow rate, discharge temperature and compressor shaft power of a third refrigerant. Here, the approach has been applied using data for two refrigerants (R22 and R134a) to achieve predictions for a third refrigerant’s (R407c) mass flow rate, discharge temperature, and compressor shaft power, with normalized root mean square errors of 0.01, 0.04 and 0.020, respectively. The normalization is performed based on the minimum and maximum values of the measured variable data. The technique thus presented in this study can be used to accurately predict the primary variables of interest for a scroll compressor running on a given refrigerant for which data may be limited, enabling component-level design or analysis for different operating conditions and system requirements.

Thermal Performance Analysis of the Stationary Reflector/Tracking Absorber (SRTA) Solar Concentrator

1975 ◽  
Vol 97 (3) ◽  
pp. 451-456 ◽  
Author(s):  
J. F. Kreider
Keyword(s):  
Fluid Flow ◽  
High Temperature ◽  
Flow Rate ◽  
Thermal Performance ◽  
Concentration Ratio ◽  
Heat Energy ◽  
Operating Conditions ◽  
Fluid Flow Rate ◽  
Wide Range ◽  
Temperature Heat

The performance of a novel solar energy concentrating system consisting of a fixed, concave spherical mirror and a sun-tracking, cylindrical absorber is analyzed in detail. This concentrating system takes advantage of the spherical symmetry of the mirror and its linear image which, when taken together, form a tracking, solar-concentrating system in which only the small cylindrical absorber need move. The effects of mirror reflectance, concentration ratio, heat transfer fluid flow rate, radiative surface properties, incidence angle, an evacuated absorber envelope, and insolation level upon thermal performance of the concentrator are studied by means of a mathematical model. The simulation includes first order radiation and convection processes between the absorber and its concentric glass envelope and between the envelope and the environment; radiation processes are described by a dual-band, gray approximation. The energy equations are solved in finite difference form in order that heat flux and temperature distributions along the absorber may be computed accurately. The results of the study show that high-temperature heat energy can be collected efficiently over a wide range of useful operating conditions. The analysis indicates that mirror surface reflectance is the single most important of the principal governing parameters in determining system performance. Efficiency always increases with concentration ratio although the rate of increase is quite small for concentration ratios above 50. High fluid flow rate (i.e., lower operating temperature), an evacuated envelope, or a highly selective surface can enhance performance under some conditions. The conclusion of the study is that high-temperature heat energy can be generated at high efficiency by the present concentrator with present technology in sunny regions of the world.

scholarly journals Modeling of fiber bridging in fluid flow for well stimulation applications

2019 ◽  
Vol 17 (3) ◽  
pp. 671-686 ◽  
Author(s):  
Mehdi Ghommem ◽  
Mustapha Abbad ◽  
Gallyam Aidagulov ◽  
Steve Dyer ◽  
Dominic Brady
Keyword(s):  
Fluid Flow ◽  
Numerical Model ◽  
New Product Development ◽  
Flow Rate ◽  
Empirical Studies ◽  
Operating Conditions ◽  
Solid Particles ◽  
Fluid Viscosity ◽  
Design Guideline ◽  
Fiber Loading

AbstractAccurate acid placement constitutes a major concern in matrix stimulation because the acid tends to penetrate the zones of least resistance while leaving the low-permeability regions of the formation untreated. Degradable materials (fibers and solid particles) have recently shown a good capability as fluid diversion to overcome the issues related to matrix stimulation. Despite the success achieved in the recent acid stimulation jobs stemming from the use of some products that rely on fiber flocculation as the main diverting mechanism, it was observed that the volume of the base fluid and the loading of the particles are not optimized. The current industry lacks a scientific design guideline because the used methodology is based on experience or empirical studies in a particular area with a particular product. It is important then to understand the fundamentals of how acid diversion works in carbonates with different diverting mechanisms and diverters. Mathematical modeling and computer simulations are effective tools to develop this understanding and are efficiently applied to new product development, new applications of existing products or usage optimization. In this work, we develop a numerical model to study fiber dynamics in fluid flow. We employ a discrete element method in which the fibers are represented by multi-rigid-body systems of interconnected spheres. The discrete fiber model is coupled with a fluid flow solver to account for the inherent simultaneous interactions. The focus of the study is on the tendency for fibers to flocculate and bridge when interacting with suspending fluids and encountering restrictions that can be representative of fractures or wormholes in carbonates. The trends of the dynamic fiber behavior under various operating conditions including fiber loading, flow rate and fluid viscosity obtained from the numerical model show consistency with experimental observations. The present numerical investigation reveals that the bridging capability of the fiber–fluid system can be enhanced by increasing the fiber loading, selecting fibers with higher stiffness, reducing the injection flow rate, reducing the suspending fluid viscosity or increasing the attractive cohesive forces among fibers by using sticky fibers.

scholarly journals On the morphology and amplitude of 2D and 3D thermal anomalies induced by buoyancy-driven flow within and around fault zones

Solid Earth ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 1571-1595 ◽  
Author(s):  
Laurent Guillou-Frottier ◽  
Hugo Duwiquet ◽  
Gaëtan Launay ◽  
Audrey Taillefer ◽  
Vincent Roche ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Fault Zone ◽  
3D Models ◽  
Fault Zones ◽  
Rock Properties ◽  
Thermal Anomalies ◽  
Flow Models ◽  
Temperature Anomalies ◽  
Vertical Fault ◽  
Dip Angle

Abstract. In the first kilometers of the subsurface, temperature anomalies due to heat conduction processes rarely exceed 20–30 ∘C. When fault zones are sufficiently permeable, fluid flow may lead to much larger thermal anomalies, as evidenced by the emergence of thermal springs or by fault-related geothermal reservoirs. Hydrothermal convection triggered by buoyancy effects creates thermal anomalies whose morphology and amplitude are not well known, especially when depth- and time-dependent permeability is considered. Exploitation of shallow thermal anomalies for heat and power production partly depends on the volume and temperature of the hydrothermal reservoir. This study presents a non-exhaustive numerical investigation of fluid flow models within and around simplified fault zones, wherein realistic fluid and rock properties are accounted for, as are appropriate boundary conditions. 2D simplified models point out relevant physical mechanisms for geological problems, such as “thermal inheritance” or pulsating plumes. When permeability is increased, the classic “finger-like” upwellings evolve towards a “bulb-like” geometry, resulting in a large volume of hot fluid at shallow depth. In simplified 3D models wherein the fault zone dip angle and fault zone thickness are varied, the anomalously hot reservoir exhibits a kilometer-sized “hot air balloon” morphology or, when permeability is depth-dependent, a “funnel-shaped” geometry. For thick faults, the number of thermal anomalies increases but not the amplitude. The largest amplitude (up to 80–90 ∘C) is obtained for vertical fault zones. At the top of a vertical, 100 m wide fault zone, temperature anomalies greater than 30 ∘C may extend laterally over more than 1 km from the fault boundary. These preliminary results should motivate further geothermal investigations of more elaborated models wherein topography and fault intersections would be accounted for.

scholarly journals Model Predictive Control of a Double Effect Evaporator Via Simulation

2021 ◽  
Vol 28 (1) ◽  
pp. 49-63
Author(s):  
Duraid Ahmed ◽  
Ihal Abed
Keyword(s):  
Dynamic Behavior ◽  
Flow Rate ◽  
Material Balance ◽  
Temperature Response ◽  
Double Effect ◽  
Difficult Problem ◽  
Operating Conditions ◽  
Feed Concentration ◽  
Operational Conditions ◽  
Wide Range

This paper is a study of the dynamic behavior of the double effect evaporator on the basis of energy and material balance under unsteady state conditions inside the evaporator. The simulation process was based on a model for the intensification of tomato juice. The mathematical model was used to study the effect of operational conditions, namely, the temperature of the feed, the flow rate of the feed, and the feed concentration. The dynamic behavior of the open system was studied by measuring the temperature response of the evaporators to the change of the staging function in the temperature of the feed, the feed flow rate and the feed concentration in the rate of (±10%, ±20%).The proportionalintegral-derivative and model predictive controllers were applied to solve the difficult problem by determining the best operational conditions and avoid a sharp increase in temperature. Two methods are tested to control a wide range of operating conditions and simulation results show that there is good accuracy. The MPC controller is more accurate than the PID control and faster to reach the constant value.

On Testing and Modeling Automotive Spool-Type Hydraulic Valve With Circular Flow Ports

2004 ◽  
Author(s):  
M. Cao ◽  
K. W. Wang ◽  
L. DeVries ◽  
Y. Fujii ◽  
W. E. Tobler ◽  
...  
Keyword(s):  
Flow Rate ◽  
Discharge Coefficient ◽  
Operating Conditions ◽  
Lumped Parameter Model ◽  
New Approach ◽  
Fluid Force ◽  
Valve System ◽  
Fluid Field ◽  
Lumped Parameter ◽  
Hydraulic Valve

This paper describes empirical investigations of the fluid field for a spool-type hydraulic valve with symmetrically distributed circular ports that is often found in an automotive VFS (Variable Force Solenoid) valve system. Through extensive data analysis, a general trend of fluid force and flow rate is derived as a function of pressure drop and valve opening. Aiming at further revealing the insights of the steady state spool valve fluid field, the equivalent jet angle and discharge coefficient are calculated from the measurements based on the lumped parameter models. New Non-Dimensional Artificial Neural Network (NDANN)-based hydraulic valve system models are also developed in this paper through the use of equivalent jet angle and discharge coefficient. By introducing the outputs of the new NDANN models into the lumped parameter model, fluid force and flow rate can be easily calculated. Therefore, the new approach calculates fluid force and flow rate as well as the intermediate variables (equivalent jet angle and discharge coefficient) with useful design implications. The network training and testing demonstrate that the NDANN fluid field estimators can accurately capture the relationship between the key geometry parameters and discharge coefficient/jet angle. The new approach also maintains the non-dimensional network configuration and possesses scalability with respect to the geometry parameters and key operating conditions. All these features make the new NDANN fluid field estimator a valuable tool for automotive hydraulic system design.

Nonempirical Apparent Permeability of Shale

2014 ◽  
Vol 17 (03) ◽  
pp. 414-424 ◽  
Author(s):  
H.. Singh ◽  
F.. Javadpour ◽  
A.. Ettehadtavakkol ◽  
H.. Darabi
Keyword(s):  
Fluid Flow ◽  
Pore Size ◽  
Flow Rate ◽  
Gas Flow ◽  
Operating Conditions ◽  
Pore Geometry ◽  
Apparent Permeability ◽  
Knudsen Flow ◽  
Proposed Model ◽  
Shale Reservoirs

Summary Physics of fluid flow in shale reservoirs cannot be predicted from standard flow or mass-transfer models because of the presence of nanopores, ranging in size from one to hundreds of nanometers, in shales. Conventional continuum-flow equations, such as Darcy's law, greatly underestimate the fluid-flow rate when applied to nanopore-bearing shale reservoirs. As a result of the existence of nanopores in shales, the molecular mean free path becomes comparable with the characteristic geometric scale, and we hypothesize that under this condition, Knudsen diffusion, in addition to correction for the slip boundary condition, becomes the dominant mechanism. Recently, a few models have been developed that use various empirical parameters to account for these modifications (Javadpour 2009; Civan 2010; Darabi et al. 2012). This paper aims to provide a different approach to modeling apparent permeability in shale reservoirs. The proposed model is analytical, free of any empirical coefficients, and has been derived without invoking the assumption of slip flow at the pore wall. Our model of apparent permeability represented by a single analytical equation, depends only on pore size, pore geometry, temperature, gas properties, and average reservoir pressure. The proposed model is valid for Knudsen numbers less than unity and it stands up under the complete operating conditions of a shale reservoir. Our model reasonably predicts results as reported by other models. Finally, the model shows that pore-surface roughness and mineralogy have a negligible influence on gas-flow rate, whereas pore geometry and pore size play a significant role in the proportion of diffusion in total flow rate. Our study shows that a combination of Darcy flow and Knudsen flow—ignoring the Klinkenberg effect—can describe gas flow for a range of Knudsen flow applicable to a shale-gas system.

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