The Challenge of Air Valve Selection in Pumping Systems

2021 ◽  
Author(s):  
Leila Ramezani ◽  
Jean-Luc Daviau
Keyword(s):  
Air Valve

scholarly journals Experimental and Numerical Study on Water Filling and Air Expelling Process in a Pipe with Multiple Air Valves under Water Slow Filling Condition

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2511
Author(s):  
Jintao Liu ◽  
Di Xu ◽  
Shaohui Zhang ◽  
Meijian Bai
Keyword(s):  
Numerical Model ◽  
Stokes Equations ◽  
Numerical Study ◽  
Practical Method ◽  
Navier Stokes ◽  
Physical Processes ◽  
Two Phase ◽  
Saint Venant Equations ◽  
Water Filling ◽  
Air Valve

This paper investigates the physical processes involved in the water filling and air expelling process of a pipe with multiple air valves under water slow filling condition, and develops a fully coupledwater–air two-phase stratified numerical model for simulating the process. In this model, the Saint-Venant equations and the Vertical Average Navier–Stokes equations (VANS) are respectively applied to describe the water and air in pipe, and the air valve model is introduced into the VANS equations of air as the source term. The finite-volume method and implicit dual time-stepping method (IDTS) with two-order accuracy are simultaneously used to solve this numerical model to realize the full coupling between water and air movement. Then, the model is validated by using the experimental data of the pressure evolution in pipe and the air velocity evolution of air valves, which respectively characterize the water filling and air expelling process. The results show that the model performs well in capturing the physical processes, and a reasonable agreement is obtained between numerical and experimental results. This agreement demonstrates that the proposed model in this paper offers a practical method for simulating water filling and air expelling process in a pipe with multiple air valves under water slow filling condition.

Uncertain Gain and Time-Delay Control of 300-kW SOFC-GT

2021 ◽  
Author(s):  
Tooran Emami ◽  
David Tucker ◽  
John Watkins
Keyword(s):  
Fuel Cell ◽  
Time Delay ◽  
Pid Controller ◽  
Transfer Functions ◽  
Cell Mass ◽  
Electric Load ◽  
Cold Air ◽  
Internal Gain ◽  
Air Valve ◽  
Turbine Speed

Abstract This paper presents a Proportional Integral Derivative (PID) controller design with the presence of an uncertain internal gain and additional time delay in the forward path of a 300 kW Solid Oxide Fuel Cell-Gas Turbine (SOFC-GT). The outputs of the system are turbine speed and the fuel cell mass flow rate. A fixed set of proportional controller coefficients are determined to graphically develop an area of selection for the integral and derivative coefficients of the PID controller. The inputs to the power plant are the electric load and cold air valve. The decentralized controllers are applied to four sub-systems as a Single Input Single Output (SISO). The PID controller coefficients are selected from a singular matrix solution that stabilizes the system and satisfies the internal gain and time delay uncertainties. Two sub-systems are the transfer functions of the turbine speed over the electric load and the cold air valve. The other two sub-systems are the transfer functions of the fuel cell mass flow rate over the electric load and the cold air bypass valve. Multiple options for selecting PID controller coefficients are beneficial to the SOFC-GT plant due to the wide range of operations and internal uncertainty interactions. The specific internal time delay and gain margins increase the reliability and robustness of the SOFC-GT with multiple uncertain parameters.

Discussion on the Harm and Protection of Water Hammer of Cavities Collapsing during Long Distance Water Transfer Project

2013 ◽  
Vol 777 ◽  
pp. 407-411
Author(s):  
Li Zhao ◽  
Yu Dong Lu
Keyword(s):  
Water Hammer ◽  
Water Transfer ◽  
Constant Speed ◽  
Long Distance ◽  
Hydraulic Impact ◽  
Tube Explosion ◽  
Valve Effect ◽  
Air Valve ◽  
Pipeline Pressure

In long distance water transfer project, the pipeline pressure caused by the change of hydraulic impact on pipeline is the most dangerous, which cavities hammer boost up to the general water several times, the tube explosion phenomenon is most caused by water hammer of cavities collapsing. After long-term practice, two-way surge tower and constant speed buffer air valve effect remarkable on water hammer of cavities collapsing.

scholarly journals Study on the Mathematical Model of Vacuum Breaker Valve for Large Air Mass Conditions

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1358
Author(s):  
Zhang ◽  
Fan ◽  
Yu ◽  
Zhang ◽  
Lv ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Theoretical Basis ◽  
Isothermal Process ◽  
Air Mass ◽  
Protection Scheme ◽  
Calculation Results ◽  
Air Valve ◽  
The Mathematical Model ◽  
Valve Model ◽  
Derivation Process

The mathematical model of vacuum breaker valve is significant to the protection scheme. The more accurate the vacuum breaker valve model, the more reliable the calculation results. In this study, the application conditions of the air valve model are analyzed according to the assumptions used in the derivation, and the contradictions between these assumptions are proposed. Then, according to the different working characteristics between the vacuum breaker valve on the siphon outlet pipe and the air valve, the vacuum breaker valve model is deduced based on the modified assumptions. In the derivation process, the thermodynamic change of the gas in the vacuum breaker valve is assumed to follow the isentropic process rather than an isothermal process, and the water level in the vacuum breaker valve is considered to be changeable. An engineering case is introduced, and the results calculated according to the vacuum breaker valve model are compared with those resulting from the air valve model. The results indicate that the vacuum breaker valve model is suitable for large air mass conditions and can provide a theoretical basis for the numerical simulation and settings of vacuum breaker valves.

A phrenic nerve-actuated electronically controlled positive-pressure ventilator

1987 ◽  
Vol 62 (5) ◽  
pp. 2121-2125 ◽  
Author(s):  
E. R. Schertel ◽  
D. A. Schneider ◽  
D. L. Howard ◽  
J. F. Green
Keyword(s):  
Moving Average ◽  
Inspiratory Flow ◽  
Positive Pressure ◽  
Feedback Signal ◽  
Position Signal ◽  
Tracheal Pressure ◽  
Valve Position ◽  
Air Valve ◽  
The Difference ◽  
Operational Modes

We have constructed an electronically controlled positive-pressure ventilator actuated by phrenic neural activity for use in open-chested or paralyzed experimental animals for the study of breathing pattern. A Bird Mark 14 positive-pressure ventilator was modified such that flow is a linear function of a command signal. Flow is delivered by advancing an air valve with a servo-motor that is controlled by one of three different operational modes. In two of the modes, the difference between the electronic average of inspiratory phrenic activity (moving average) and a feedback signal determines the inspiratory flow. The feedback signal is derived from either tracheal pressure or an electronic measure of inspired volume. In the third mode, the moving average is differentiated to provide control of inspiratory flow and volume. Physiological flow profiles were created using all three operational modes. Integration of an air-valve position signal provides an electronic measure of tidal volume. An additional feature of this ventilator allows inspiratory flow and duration to be predetermined for a given breath.

Solutions for Air Valve Breakage Caused by Hydraulic Transients in Pinellas County's Wastewater Force Main System

2009 ◽  
Vol 2009 (2) ◽  
pp. 143-163 ◽  
Author(s):  
Guohua Li ◽  
Christopher C. Baggett ◽  
John H. Horvath ◽  
Mike Engelmann ◽  
William H. Gill
Keyword(s):  
Hydraulic Transients ◽  
Main System ◽  
Air Valve

A novel approach to disturbance rejection in idle speed control towards reduced idle fuel consumption

2003 ◽  
Vol 217 (8) ◽  
pp. 677-690 ◽  
Author(s):  
C Manzie ◽  
H C Watson
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Multiple Input Multiple Output ◽  
Speed Control ◽  
Idle Speed ◽  
Novel Approach ◽  
Idle Speed Control ◽  
Bypass Valve ◽  
Input Multiple Output ◽  
Air Valve

Idle speed control remains one of the most challenging problems in the automotive control field owing to its multiple-input, multiple-output structure and the step nature of the disturbances applied. In this paper a simulation model is described for a 4.0 l production engine at idle which includes the standard bypass air valve and spark advance dynamics, as well as the e ects of operating point on cycle-by-cycle combustion-generated torque variations. A model predictive control scheme is then developed for the idle bypass valve and spark advance. The idle speed control algorithm is based on rejecting the torque disturbance using model predictive control for the bypass valve duty cycle while minimizing the transient e ects of the disturbance by adjusting the spark advance. Simulation results are presented to demonstrate the effects of different elements of the controller such as levels of spark offset from minimum spark advance for best torque at idle and feedforward load previews. Compensation of the effects of cyclic variation in combustion torque is also implemented in the controller and its benefits are discussed.

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