Valve Pressure Drop Research Articles

Thermodynamic analysis of a combined heating and power plant hybrid with compressed air energy storage and molten salt heat storage

In face of the increasing penetration of renewable energy, compressed air energy storage (CAES) is promising in improving the flexibility of the conventional coal-fired combined heating and power plant (CHPP). In order to further broaden the operational range and improve the overall efficiency, this paper introduces the molten salt heat storage (MSHS) into the CHPP-CAES system. Based on the thermodynamic model, the effect of the MSHS is discussed in terms of the energy efficiency, exergy efficiency, and the power regulation based on the topology with and without MSHS. The inclusion of the MSHS can improve the exergy efficiency and reduce the average coal consumption for power supply, while also effectively widening the power regulation range. Parameter analysis is carried out in terms of the compression and expansion stages of CAES, the steam extraction position of MSHS, throttle valve pressure drop, and the capacities of CAES and MSHS. It is revealed that, extracting steam from the boiler reheater and reducing the CAES capacity can lead to better efficiency but smaller operational range. Furthermore, reducing the throttle valve pressure drop and improving the MSHS capacity are simultaneously favorable for the overall performance and operating range. These conclusions can provide theoretical guidance for the structure and parameter design of the CHPP in hybrid with CAES and MSHS.

Analysis of Fluid Pressure Drop through a Globe Valve using Computational Fluid Dynamics and Statistical Techniques

Fluid mechanics plays a crucial role in everyday life, enabling the selection of accessories, materials, and various components essential for a system through which fluid flows. Pressure drop stands out as one of the most relevant factors in the design of fluid flow systems. However, analytical and experimental physical methods can increase these analyses' costs and time. Hence, in this study, statistical tools are employed to carry out specific experiments supported by numerical fluid simulation, aiming to comprehend the pressure drop behavior in a fluid as it passes through a globe valve. This valve, in turn, possesses distinct operating and manufacturing characteristics. The methods employed encompass a complete factorial system of response surface as support to construct the experimental design path through computational fluid dynamics. Among the key findings, it is demonstrated that, for systems with relatively low flow rates, the valve opening percentage does not exhibit a significant relationship with fluid pressure drop. Conversely, significant effects are observed for systems with relatively high flow rates regarding the valve opening percentage and pressure drop, reaching values of up to 73% pressure drop in this study. It can be inferred that the integration of statistical experimental design techniques and computational fluid dynamics constitutes a valuable resource for studying the pressure drop of a fluid passing through a system.

Analysis of pressure drop and response characteristics of an enhanced radial magnetorheological valve based on magneto-fluidic coupling

To analyze the pressure drop characteristics of MR valves more realistically, a simulation method of coupling electromagnetic field and flow field was proposed in this paper. An enhanced radial MR valve with radial and annular compound paths was proposed, and its structure and working principle were also elaborated. Next, the mathematical equation of pressure drop was established using the non-Newtonian constitutive model of MR fluid Bingham-Papanastasiou. The dual physical model was completed by the sequential coupling way based on Maxwell equation and Naiver stokes equation. The distribution law of electromagnetic field and flow field in the process of mutual coupling was numerically simulated by COMSOL software. Furthermore, a series of pressure drop and response characteristics tests were performed for the proposed MR valve. Through the experimental analysis, it could be seen that the pressure drop and response time of the MR valve hardly change with the applied load and flow rate, while the pressure drop increases significantly and the dynamic response time basically decreases with the augment of the applied current. At an excitation current of 1.6 A, the maximum pressure drop of the experiment and simulation was 4.46 MPa and 4.84 MPa, respectively. Consequently, all the maximum relative errors were less than 7.9 %.

Comparative Analysis of the Performance Characteristics of Butterfly and Pinch Valves

Valves are important components in controlling the amount of fluid going to devices. One of these types is the butterfly valve (BFV) that adjusts the amount of flow by rotating the valve disk by means of its shafts which is usually located in the middle of the flow. Despite its common usage in various applications, the BFV is known to cause a high-pressure drop. Conversely, the pinch valve is another type of flow control device that uses a pinching mechanism to open and close the inner tube by pinching at different degrees. The absence of flow-controlling mechanisms in the flow path, such as the valve disk and its shaft, contribute to the minimal pressure drop in pinch valves. The high-pressure drop in BFVs and the minimal pressure drop in pinch valve flow make it worthwhile to investigate and compare their flow at all opening positions of the two valves. Therefore, this work numerically explores the potential of using the pinch valve as an alternative to the BFV in terms of its ability to attain a lower pressure loss, hence better flow rate. The influence of various BFV parameters such as shaft diameter, valve thickness, and valve disk edge were examined. The performance characteristics of both valves were obtained using CFD models formed on the SolidWorks program. This CFD model solves the differential equations using the finite element method. Moreover, a mathematical model to determine the area of the pinch valve at various pinching degrees was developed and compared with the results obtained from other mathematical models and CFD. It was shown that using a flat 1 mm valve disk thickness with round edges resulted in a 7.5% increase in mass flow rate compared to standard BFVs. On the other hand, using the pinch valve resulted in over a 700% mass flow rate compared to the BFV at a 25% opening position and a 49% increase in flow rate at a 75% opening position. Thus, the pinch valve has the potential to replace the BFV due to its better flow characteristics in any application.

Entropic Analysis of Processes in Control Valves

The thermodynamic analysis of irreversible processes has an important influence in energy efficiency growing of any thermodynamic processes or systems. All of thermodynamic processes are entropy generators but there are processes with such a high level of irreversibility so that couldn’t be ignored. That is why is so important to identify what causes entropy generation and also to identify those system components that contribute the most to the overall irreversibility of the thermodynamic system. One of the processes with the highest level of entropy generation is flow with friction in various ducts and flow networks such as control valves. In order to see the direct connection between frictional pressure drop and thermodynamic irreversibility the paper will firstly analyze the steady and adiabatic flow of pure substance through a short segment of pipe with variable section (control valve). Because the entropy generation value during the throttling process is proportional to control valve pressure drop, the paper will do a flow thermodynamic analysis inside the control valve and the conclusions about drop pressure in different working conditions will be taken. Pressure drops along a valve are not constant, but rather vary in relation to the port left open by the plug. They normally increase as the valve narrowest section is reduced, although the upstream drop does increase at a slower rate than the downstream one. Actual increases and decreases in pressure drop and their effects are related to valve type and flow direction. It can be deduced that, for all types, pressure drops increase at flow tending to close, mainly as a result of the increased drop generated downstream. Also, the paper will take into account the drop pressure variation during the substance flow and will be analyzed its influence on the process irreversibility. In the same time, the paper will analyze the change of state influence during the liquid throttling process on the entropy generation, in situations of low titer bipolar phase fluid or high titer bi-phase fluid and will identify this phenomenon effects and remedies.

Modeling of an industrial mixing valve and electrostatic coalescer for crude oil dehydration and desalination

ABSTRACT This paper aims to present a new model for an industrial desalination system including a mixing valve and an electrostatic coalescer. This model uses a one-dimensional population balance equation in steady-state conditions. The effect of hydrodynamic, diffusion and electrostatic mechanisms on the collision or breaking of water droplets dispersed in crude oil was considered. Also, using the film drainage model, the droplet coalescence rate has been determined. The developed model can predict the outlet droplet size distribution as well as the desalination and dehydration efficiency. The simulation results showed good agreement with the industrial data. Finally, the effect of some important parameters on the electrostatic desalination process, such as mixing valve pressure drop, electric field intensity, crude oil viscosity, crude oil temperature, diluting water flow rate, and crude oil API on the efficiency of the process was analyzed. The results indicated that by increasing the crude oil temperature from 314 to 334 K, the efficiency of dehydration improves from 97.95% to 99.02%. Also, reducing crude oil API from 33 to 30 and crude oil viscosity from 4 to 2 mPa.s caused a decrease in water separation by 2.88% and 1.16%, respectively.

Theoretical and experimental study on performance of compound-driven MR valve-controlled damper

A compound-driven magnetorheological (MR) valve is designed to cope with the low reliability and high energy consumption of traditional MR valves. The operating magnetic field of the valve is applied by both the excitation coil and ring magnet, maintaining excellent pressure drop performance even at zero current. To analyze the performance and obtain the variation law of the magnetic flux density and pressure drop, a pressure drop mathematical model and a magnetic field simulation model are established. The key parameters of the MR valve are also optimized using non-dominated sorting genetic algorithms-II. A dynamic performance test system is built, and the influence of the load on the pressure drop and hysteresis characteristics of the MR valve is studied. The results show that the optimized pressure drop and adjustable coefficient are improved by 4.7% and 8.6% respectively. The pressure drop grows nonlinearly with the electric current and reaches saturation at a current of 1.5 A, and a pressure drop of 1485 kPa is still generated at zero current. The output damping force of the compound-driven MR valve-controlled damper can be continuously adjustable, indicating that the dynamic performance of the damper can be controlled by adjusting the input current.

Flow characteristics and flow rate prediction of pulverized coal through a regulation valve

• The optimum valve sweeping gas fraction was determined. • Control characteristics of the regulation valve were studied. • Limit operating conditions of the regulation valve were defined. • A semi-empirical model was established for pulverized coal flow rate prediction. In this paper, experiments of dense-phase pneumatic conveying of pulverized coal were carried out in an industrial-scale system to study the control characteristics of the regulation valve and to predict the solid mass flow rate. Firstly, effects of valve sweeping gas on conveying stability and solid mass flow rate were investigated and the optimum valve sweeping gas was determined. Second, effects of valve opening on pressure distribution and solid mass flow rate were investigated by conducting experiments at different conveying pressure drops and different valve openings. A good linear relationship between the valve pressure drop ratio and the valve opening was found, and as the valve opening increased from 13 % to 70 % the solid mass flow rate increased gradually. Limit operating conditions of the regulation valve including flow blockage and control failure were consequently determined and analyzed. Finally, a robust model was established to predict the solid mass flow rate by introducing the valve sensitivity coefficient into the traditional pressure drop ratio model. The model can predict the solid mass flow rate well by providing errors mostly within ± 10 %. This study will provide certain reference for solid mass flow rate regulation in the dry coal gasification process.

Thermodynamic analysis and efficiency improvement of trans-critical compressed carbon dioxide energy storage system

A novel trans-critical compressed carbon dioxide energy storage (TC-CCES) system was proposed in this paper, then the sensitivity analysis of thermodynamic with a 10 MW unit as the target were conducted, and finally the round-trip efficiency (RTE) of system was improved through distributing the pressure of key nodes and adopting the design method of non-equal pressure ratio. It can be concluded by sensitivity analysis that the system thermodynamic can be improved by increasing the isentropic efficiency of compressors and turbines, increasing the energy release pressure, reducing the outlet pressure of turbines, the pressure drop of high-pressure throttle valve, and the temperature difference of heat exchangers. The RTE of system with non-equal compression ratio and equal expansion ratio can be up to 74 % when the stages are three and the compression temperature is 115 °C. Compared with 65.44 % RTE without the method of pressure distribution at key nodes and non-equal pressure ratio design, the RTE of system is increased by 6.46 %.

Dynamic simulation of aortic valve stenosis using a lumped parameter cardiovascular system model with flow regime dependent valve pressure loss characteristics.

Valvular heart diseases are growing concern in impoverished parts of the world, such as Southern-Africa, claiming more than 31 % of total deaths related to cardiovascular diseases. The ability to model the effects of regurgitant and obstructive lesions on the valve body can assist clinicians in preparing personalised treatments. In the present work, a multi-compartment lumped parameter model of the human cardiovascular system is developed, with a newly proposed valve modelling approach which accounts for geometry and flow regime dependent pressure drops along with the valve cusp motion. The model is applied to study various degrees of aortic stenosis using typical human cardiovascular parameters. The predicted transvalvular pressure drops for the different modelling approaches are compared to typical measured mean and peak gradients found in literature for severely stenosed aortic valves. The comparison between the predicted and measured values show that the previously published valve models under predicts expected severely stenosed peak and mean transvalvular pressure drops by approximately 47% and 25% respectively, whereas the newly proposed model under predicts the peak pressure drop by 25% and over predicts mean pressure drop by 7%.

Thermoregulatory and cardiovascular responses to up-step change transient thermal environments: A risk factor in individuals with prosthetic heart valves

Exposure to step-change thermal environments can trigger the human body's thermoregulatory processes. The reactivation of thermoregulatory mechanisms is usually accompanied by the excitation of cardiovascular responses. This paper presents a combined thermoregulatory-cardiovascular model for predicting the effect of transient thermal environments on heart rate and cardiovascular responses. The proposed model was validated against multiple sets of experimental data reported in the literature. The validation results showed that the proposed model, which considers the thermoregulatory effects, could predict heart rate more accurately compared to the Givoni and Goldman practical model. The impacts of different up-step temperature changes on cardiovascular responses were investigated using the proposed model. The results showed that exposure to a relatively small (10°C), medium (20°C), and large (30°C) up-step temperature changes increased the heart rate by about 7%, 20%, and 35%, respectively. It was also found that ambient relative humidity did not have remarkable effects on cardiovascular responses. The results of our analysis performed in the temperature range of 20°C to 50°C showed that the heart rate could reflect the reactivation of the body's thermoregulatory mechanisms. The findings indicated that in people with artificial heart valves, sudden exposure to temperature step-changes of 10°C to 30°C could increase the heart valve pressure drop by about 14%–85%, greatly increasing the risk of blood damage. Furthermore, it is concluded that the proposed model can pave the path for utilizing integrated wearable devices for predicting individualized thermal comfort and managing cardiovascular health risks associated with ambient heat stresses.

Modeling and Experiments of an Annular Multi-Channel Magnetorheological Valve

With the increasing number of cars, the demand for vehicle maintenance lifts is also increasing. The hydraulic valve is one of its core components, but there are problems with it such as inaccurate positioning and failure. In order to improve the service performance of vehicle maintenance elevators, a novel annular multi-channel magnetorheological (MR) valve structure was creatively proposed based on intelligent material MR fluid (MRF), and its magnetic circuit was designed. The influence of current, damping gap and coil turns on the pressure drop performance of the annular multi-channel MR valve was numerically studied and compared with ordinary type magnetorheological valve pressure drop performance through contrast and analysis. The influence of different loads and currents on the pressure drop performance of annular multi-channel magnetorheological valve was verified by experiments, and the reliability of numerical analysis results was verified. The results show that the single winding excitation coil is 321 to meet the demand. The pressure drop performance of the annular multi-channel magnetorheological valve is 5.6 times that of the ordinary magnetorheological valve. The load has little influence on the regulating range and performance of pressure drop of the MR valve. Compared with the common type, the pressure drop performance of the annular multi-channel MR Valve is improved by 3.7 times, which is basically consistent with the simulation results.

Design analysis of a novel orifice control valve for turbomachinery testing facilities

In testing facilities for turbomachinery applications, the main component for the regulation of the flow is the control valve. In order to fulfill the flow rate requirements, the performance of the control valve should be highly accurate in a specified flow range. The robustness against variations or disturbances, is a major issue to be considered. A control valve incorporated in any testing facility has to meet certain requirements. Thus, operating aspects, such as the flow rate range and the valve pressure drop, along with control prerequisites, regarding flow stability, repeatability and robustness of the valve, are considered. The purpose of this study is to establish a new designing approach for control valves. Orifice plates are used as a guideline for this study because of the geometrical similarities with the control valve. A sensitivity analysis determines the most influential parameters and prioritizes the requirements. With emphasis on the cross-sectional area and by neglecting its shape, a simplified 2-D model is optimized. Eventually, a CFD model, verified by experiments, is used for the analysis of the effects of geometrical parameters. The established workflow weighs the requirements according to each application and indicates the method to reach the desired goals. CFD simulations verify the 2-D model and assist in the fine adjustment of the control valve’s characteristics. With an average deviation of 3% between the 2-D and the 3-D model, the simplified 2-D model proves to be sufficient for setting the valve’s characteristics, setting the CFD simulations necessary, only in applications of extreme flow rates and temperature conditions.

Dynamic Performance Analysis of a Compact Annular-Radial-Orifice Flow Magnetorheological Valve and Its Application in the Valve Controlled Cylinder System

A compact annular-radial-orifice flow magnetorheological (MR) valve with variable radial damping gaps was proposed, and its structure and working principle were also described. Firstly, a mathematical model of pressure drop was established as well to evaluate the dynamic performance of the proposed MR valve. Sequentially, the pressure drop distribution of the MR valve in each flow channel was simulated and analyzed based on the average magnetic flux densities and yield stress along the damping gaps through finite element method. Further, the experimental test rig was setup to explore the pressure drop performance and the response characteristic of the MR valve and to investigate dynamic performance of the valve controlled cylinder system under different radial damping gaps. The experimental results revealed that the pressure drop and response time of the MR valve augment significantly with the increase of applied current and decrease of the radial damping gap. In addition, the damping force of the proposed MR valve controlled cylinder system decrease with the increase of the radial damping gap. The maximum damping force can reach about 4.72 kN at the applied current of 2 A and the radial damping gap of 0.5 mm. Meanwhile, the minimum damping force can reach about 0.67 kN at the applied current of 0 A and the radial damping gap of 1.5 mm. This study clearly demonstrates that the radial damping gap of the MR valve is the key parameter which directly affects the dynamic characteristics of the valve controlled cylinder system, and the proposed MR valve can meet the requirements of different working conditions by changing the radial damping gaps.

Numerical and experimental studies of gas-liquid flow and pressure drop in multiphase pump valves.

A numerical and experimental study was carried out to investigate the two-phase flow fields of the typical three valves used in the multiphase pumps. Under the gas volume fraction conditions in the range of 0%-100%, the three-dimensional steady and dynamic two-phase flow characteristics, pressure drops, and their multipliers of the ball valve, cone valve, and disk valve were studied, respectively, using Eulerian-Eulerian approach and dynamic grid technique in ANSYS FLUENT. In addition, a valve test system was built to verify the simulated results by the particle image velocimetry and pressure test. The flow coefficient CQ (about 0.989) of the disk valve is greater than those of the other valves (about 0.864) under the steady flow with a high Reynolds number. The two-phase pressure drops of the three valves fluctuate in different forms with the vibration of the cores during the dynamic opening. The two-phase multipliers of the fully opened ball valve are consistent with the predicted values of the Morris model, while those of the cone valve and disk valve had the smallest differences with the predicted values of the Chisholm model. Through the comprehensive analysis of the flow performance, pressure drop, and dynamic stability of the three pump valves, the disk valve is found to be more suitable for the multiphase pumps due to its smaller axial space, resistance loss, and better flow capacity.

Pressure drop in valve for different open flow areas

In any piping system different types of regulating components (valves) are used. To determine the pressure drop of the liquid in these components, it is necessary to know the exact values of the local loss coefficients, which depend on their design and manufacturer. The calculations of local loss coefficients of the valves are usually carried out according to engineering methods using design handbooks. However, the large design diversity of the valves does not allow an accurate assessment of the local loss coefficient for a particular product (using handbooks). There are two ways to solve this problem. The first way is experimental determination; the second is calculation using CFD modelling. This article presents the results of CFD simulation of the pressure drop of liquid through valves and a comparison with experimental data obtained from the thermal hydraulic test bench.

Two-Phase Expander Approach for Next Generation of Heat Recovery Systems

This study presents the numerical adaptations to the semi-empirical expander model in order to examine the feasibility of piston expanders under off-design and two-phase scenarios. This expander model considers supply valve pressure drop, condensation phenomena, heat losses, leakage losses and friction losses. Using Aspen HYSYS©, the expander model is utilised in simulating the next generation of integrated engine cooling and exhaust heat recovery system for future heavy-duty engines. The heat recovery system utilises water-propanol working fluid mixture and consists of independent high pressure (HP) and low pressure (LP) expander. The results of off‑design and two-phase operation are presented in terms of expander efficiency and the different sources of loss, under two distinctive engine speed-load conditions. The heat recovery system, operating with the LP expander at two-phase and the HP expander at superheated condition, represented the design point condition. At the design point, the system provided 15.9 kW of net power, with an overall conversion efficiency of 11.4%, representing 10% of additional engine crankshaft power. At the extreme off-design condition, the two-phase expander operation improved the system performance as a result of the nullification of leakage losses due to the much denser working fluid. The optimised two-phase operation of the LP expander (x=0.55) and the HP expander (x=0.9) at the extreme-off design condition improved the system power by nearly 50% (17.4 vs. 11.7 kW) compared to the reference state. Finally, adapting piston air motors as two-phase expanders for experimental evaluation and reduction in frictional losses was a recommended research direction. ©2019. CBIORE-IJRED. All rights reserved

Experimental study and numerical simulation on in-cylinder flow of small motorcycle engine

This study aimed at experimental and numerically investigating in-cylinder flows of a small motorcycle engine under steady-state conditions. The experiment was conducted in the engine head for a variety of fixed valve lifts at two pressure drops (300 and 600 mmH2O). Besides, this study attempted to analyze the characteristics of in-cylinder flows in a small engine by applying CFD methods. Looking at the results, there was a good agreement between the results of experiment and simulation in terms of flow coefficient, air flow rate and discharge coefficient at two pressure drops. In both horizontal and vertical planes, both increased valve lift and pressure drop delivered increased velocity and vorticity magnitude. An increase in pressure drop at the beginning of valve lift opening appeared to have no effect on the swirl ratio until the valve lift reached 5 mm. However, the swirl ratio got a 25% reduction when the valve lift reached 6.25 mm. An increase in pressure drop at the intake stroke did not deliver a significant effect on the tumble ratio and accumulated air mass. However, the accumulated air mass increased 3.77% at compression stroke. An increase in pressure drop delivered a significant effect on turbulent kinetic energy (TKE), turbulent length scale and turbulent kinematic viscosity. TKE reached its peak (200%) at 470 °CA, while turbulent length scale and turbulent kinematic viscosity reached their peaks at 590 °CA where the intake valve was almost closed. The increase in turbulence in fact produced a more homogeneous in-cylinder air-fuel mixing. Besides, the increase in turbulence directly increased the rate of fire propagation. Further study would be expected to focus on modifying the design of intake port for improving the air flow characteristics of small engines. Then, this study was expected to reduce the number of experiments required for investigating optimized parameters in small engines.

Investigation of the Pre-Treatment for Reducing Salt and Sediments in Khurmala Oil Field

Oil produced in most of the oil fields is accompanied by water in the form of an emulsion that must be treated. This water normally contains dissolved salts, principally chlorides of sodium, calcium, and magnesium. If crude oil is left without treatment, the salt will cause various operational problems. This research investigates experimentally the effect of major factors on the efficiency of the desalting process for a Khurmala crude oil in Kurdistan Region. These factors are chemical treatment, PH value of water, temperature and pressure drop. One of the factors is systematically varied when the others are constant and the efficiency is analyzed. It was found that the best desalter efficiency can be concluded when the embreak dosage is 100 ppm, PH of wash water 6.5 in average, the optimum temperature is 55°C and pressure drop of mixing valve is 1.5 bars and the best desalter efficiency was in acidified condition.

Performance Simulation Analysis for Magnetorheological Damper with Internal Meandering Flow Valve

Magnetorheological (MR) damper as a semi-active system for a vehicle suspension is simulated in this study. The proposed design of Magnetorheological (MR) valve consists of meandering flow channel or gaps that fixed in the piston of the damper. The focus of this study is to estimate the performance of proposed MR valve based on actual front suspension parameter of a vehicle. Annular and radial gaps are combined to produce an MR valve with meandering fluid flow path. Furthermore, the damper is filled with Magnetorheological (MR) fluid to energize the damper under the presence of magnetic fields. The magnetic flux density within each gap is obtained via the Finite Element Method Magnetics (FEMM) software. Therefore, the yield stress of MR fluid and magnetic flux relationships both can be predicted. The present paper shows a reduction in pressure drop when the thickness of each gap is increased. Pressure drop is closely affected by the fluid flow rate that enters each gap. This means that the lower flow rate increases the pressure drop of MR valve at various current.