Non Return Override Valve - MapleSim Help

Non Return Override Valve

Non return override valve

Description

The Non Return Override Valve component is a check valve with a pilot pressure that can be used to assist in opening or closing the valve.

The sonic conductance of the valve is assumed to be a piecewise linear function of the pressure difference between port A and port B.

Based on the orifice area, the pressure vs. flow rate relationship is calculated by the formulation used in the Orifice ISO 6358 component.

 Formulation Approaches Two approaches were taken for formulation of the flow equation inside the device. When the boolean parameter $\mathrm{UseRestrictionArea}$ is true, the flow area at the local restriction can be provided which will be converted to sonic conductance using Gidlund's approximation.
 Equations $p={p}_{A}-{p}_{B}\phantom{\rule[-0.0ex]{0.0em}{0.0ex}}\phantom{\rule[-0.0ex]{0.0em}{0.0ex}}$ Orifice Gas Equations Linear Gain k is given by When UseRestrictionArea is checked, Gidlund's approximation is used to calculate C using $\mathrm{Ar__max}$ $\mathbf{Pilot Equations}$ ${C}_{t}=\left\{\begin{array}{cc}{C}_{\mathrm{min}}& {p}_{\mathrm{tot}}\le {p}_{\mathrm{close}}\\ {C}_{\mathrm{min}}+\left({p}_{\mathrm{tot}}-{p}_{\mathrm{close}}\right)\frac{{C}_{\mathrm{max}}-{C}_{\mathrm{min}}}{{p}_{\mathrm{open}}-{p}_{\mathrm{close}}}& {p}_{\mathrm{tot}}<{p}_{\mathrm{open}}\\ {C}_{\mathrm{max}}& \mathrm{otherwise}\end{array}$ ${p}_{\mathrm{tot}}=p+\left\{\begin{array}{cc}{k}_{p}{p}_{C}& \mathrm{dir}=1\\ -{k}_{p}{p}_{C}& \mathrm{otherwise}\end{array}$ ${\mathrm{mflow}}_{C}=0$

Variables

 Name Units Description Modelica ID $p$ $\mathrm{Pa}$ Pressure drop from A to B p ${p}_{X}$ $\mathrm{Pa}$ Pressure at port X pX $\mathrm{mflow}$ $\frac{\mathrm{kg}}{s}$ Mass flow rate from A to B mflow ${\mathrm{hflow}}_{X}$ $\frac{J}{\mathrm{kg}}$ Specific Enthalpy into port X hflowX

Connections

 Name Description Modelica ID $\mathrm{portA}$ Pneumatic port on left side portA $\mathrm{portB}$ Pneumatic port on right side portB $\mathrm{portC}$ Pneumatic port on the bottom (no volume, used as pilot) portC

Parameters

Fluid Medium Parameters

The Gas parameters used in the equations are properties defined in the Gas Model component used in the model.

 Name Default Units Description Modelica ID $\mathrm{true}$  When true the default gas properties defined for Air will be used. useDefaultMedium $\mathrm{medium}$ $-$  When Use default medium is false this option gets turned on. The user can specify the name of the Gas model dragged into the canvas. medium

Orifice Parameters

 Name Default Units Description Modelica ID $\mathrm{b__lamreg}$ $0.999$ Flow transition constant from turbulent to laminar zone blamreg $\mathrm{UseRestrictionArea}$ $\mathrm{false}$ True (checked) means flow restriction area can be given which will be converted to sonic conductance based on Gidlund's approximation UseRestrictionArea

Valve Parameters

 Name Default Units Description Modelica ID ${p}_{\mathrm{crack}}$ $\mathrm{Pa}$ Pressure at which valve is fully closed (C = Cmin) pclose ${p}_{\mathrm{open}}$ $\mathrm{Pa}$ Pressure at which valve is fully open (C = Copen) popen ${C}_{\mathrm{min}}$ $\frac{{m}^{3}}{s\cdot \mathrm{Pa}}$ Valve Sonic Conductance when closed (leakage) Cmin ${C}_{\mathrm{max}}$ $\frac{{m}^{3}}{s\cdot \mathrm{Pa}}$ Valve Sonic Conductance when fully open Cmax ${A}_{\mathrm{min}}$ $0$ ${m}^{2}$ Restriction Area when closed (leakage); used when  is true Amin $\mathrm{Ar__max}$ $0.00001$ ${m}^{2}$ Valve restriction area when fully open; used when  is true Armax $b$ $0.54$ Critical pressure ratio bcr Pilot action Open Select whether the pilot operates to open or close the valve dir ${k}_{\mathrm{pilot}}$ $3$ Pilot ratio kp