# Result Table - Valves (2 Port)

The available results that are listed in the table vary depending upon the fluid phase state and upon the visible properties that you have selected. Figure 1 shows all of the available results for a liquid phase state. Figure 2 shows the normal or default rows. You can choose the rows you wish to display in the results table via the Set Visible Results Dialog. Figure 1: Available results for a valve. Only descriptions for the default results are shown in this section. If you wish to see the definition for other values click here. -- ID -- (aka User Number): All flowsheet elements have a unique number that is assigned by FluidFlow. It is not possible for the user to change this number because it is used as a unique identifier by the scripting module. Node numbering starts from 1, incrementing upwards, and pipe numbering starts from -1, decrementing downwards. Composition Mass %: This is the fluid mass composition that remains constant throughout the element. FluidFlow determines the composition because an individual component mass balance is carried out at each node. Flow: This is the valve inlet flow that FluidFlow has calculated will be flowing. For all phase states the mass flow into and out of the valve will be identical. For incompressible fluids the valve inlet and exit flows expressed in volumetric units will be identical, but this will not be the case if the temperature changes across the valve. For gas flows this represents the actual flow at the element inlet. For two phase flow of constant quality and temperature, volumetric flow will be identical, for changing quality or changing temperature volumetric inlet and outlet flows will be different. Flow at NTP: This is the volumetric flow referenced to normal conditions (0°C and 101325 Pa). NTP flow is the same as the gas flows through the element. NOTE: This result is available for Gas Calculations. Flow at STP: This is the volumetric flow referenced to standard conditions (15°C and 101325 Pa). STP flow is the same as the gas flows through the element. NOTE: This result is available for Gas Calculations. Friction Loss: This is the calculated total pressure loss. Total pressure loss is not always the same as frictional loss, for example, when a temperature or velocity change occurs. In FluidFlow total pressure loss is defined (from the Energy Equation) as Δ P = (z 1 ρ 1 g + p 1 + 0.5 ρ 1 v 1 2) - (z 2 ρ 2 g + p 2 + 0.5 ρ 2 v 2 2) Heat Transferred: If the Heat Loss Model is not equal to "Ignore Heat Loss/Gain", then an additional row will appear in the results table showing the amount of heat that has been transferred. In Mach Number: This is the ratio of inlet velocity to the velocity of sound at the inlet conditions. It is not possible to reach a mach number greater than 1 within this element. The velocity of sound is a thermo physical property and depends on temperature and pressure. NOTE: This result is available for Gas Calculations. In Stagnation Pressure: The stagnation pressure at the valve inlet. This is the sum of kinetic and pressure energies (static pressure + velocity pressure). Stagnation pressure is the pressure a flowing fluid would rise to if brought isentropically to rest, converting its kinetic energy to enthalpy. Stagnation pressure is a measure of the usefulness of the gas's energy. In Stag. Temperature: This is the stagnation temperature at the valve inlet. The stagnation temperature is the temperature that the fluid would reach if it were brought to rest isentropically, converting its kinetic energy to enthalpy. In Static Pressure: This is the pressure that acts equally in all directions at the point in the fluid and is present irrespective if the fluid is flowing or if the fluid is at rest. The pressure inside any valve is not the static pressure, unless there is no flow. Stagnation pressure is the flowing pressure. In Static Temperature: The static temperature at the valve inlet. Static temperature is related to stagnation temperature (ignoring work, heat exchange, and potential energy) by the equation T 1 = T 1 0 - 0.5 v 1 2 / C p In Velocity: The velocity at the valve inlet. For gases, velocity increases as the fluid moves across the valve. This can also occur with two phase flow where flashing exists, or for an incompressible where the temperature rises. Velocity can also decrease as a fluid flows across an element, for example cooling of a liquid. Joule–Thomson Coefficient: The Joule–Thomson effect describes the increase or decrease in the temperature of a gas when allowed to expand. The change in temperature (T) with a decrease of pressure (P) at constant enthalpy (H) is referred to as the Joule–Thomson coefficient (μJT). FluidFlow uses the Peng Robinson EOS to evaluate the Joule–Thomson coefficient which is expressed as: μ JT = (∂T/∂P)H The value of μJT is typically expressed in °C/bar and is dependent on the physical properties of the gas, as well as the temperature and pressure of the gas before expansion. K Value: This represents the Pressure Loss Coefficient (K) which has been automatically back-calculated by the software. Let's consider the valve performance data in Figure 1. The K value displayed for the Gate Valve in the results is the K value calculated from the equation: K = Δ P / 0.5 * ρ * v^2 where: ρ is the fluid density at the valve inlet in kg/m3 v is the fluid velocity at the valve inlet in m/s ΔP is the pressure drop across the valve in Pascals Therefore, K for the Gate Valve is determined as follows: K = 37.160216 / 0.5 * 999.101221 * 0.304830^2 K = 37.160216 / 46.41890658 K = 0.8 Out Mach Number: This is the ratio of outlet velocity to the velocity of sound at the outlet conditions. It is not possible to reach a mach number greater than 1 within this element. The velocity of sound is a thermo physical property and depends on temperature and pressure. NOTE: This result is available for Gas Calculations. Out Stagnation Pressure: The stagnation pressure at the valve outlet. This is the sum of kinetic and pressure energies (static pressure + velocity pressure). Stagnation pressure is the pressure a flowing fluid would rise to if brought isentropically to rest, converting its kinetic energy to enthalpy. Stagnation pressure is a measure of the usefulness of the gas's energy. Out Stag. Temperature: This is the stagnation temperature at the valve outlet. The stagnation temperature is the temperature that the fluid would reach if it were brought to rest isentropically, converting its kinetic energy to enthalpy. Out Static Pressure: This is the pressure that acts equally in all directions at the point in the fluid and is present irrespective if the fluid is flowing or if the fluid is at rest. The pressure inside a valve is not the static pressure, unless there is no flow. Stagnation pressure is the flowing pressure. Out Static Temperature: The static temperature at the element outlet. Static temperature is related to stagnation temperature (ignoring work, heat exchange, and potential energy) by the equation T 2 = T 2 0 - 0.5 v 2 2 / C p Out Velocity: The velocity at the valve outlet. For gases, velocity increases as the fluid flows across the valve. This can also occur with two phase flow where flashing exists, or for an incompressible fluid where the temperature rises. Velocity can also decrease, for example cooling of a liquid. Stagnation Pressure Loss: This is the difference between the inlet and outlet stagnation pressures. Static Pressure Loss: This is the difference between the inlet and outlet static pressures.