Transient Flow Library

Channel

Model

Models the low-pressure side of a heat exchanger. Use this model for heat exchanger tube rupture.

DynamicSettings

Model

Provides advanced Dynamics parameters that help you debug and fix issues with your Dynamics runs. We recommend that you use this model to update the integration method to use a trapezoidal method rather than implicit Euler. This increases the simulation accuracy at larger time steps.

EndElem*

Submodel

Models the end element in a Pipe model. This submodel does not include inertia. It serves as a connection between two Pipes when you place them in series. The EndElem submodel appears after an alternating series of FlowElem and WallElem submodels within the Pipe model.

Fit

Model

Allows you to enter the flow resistance due to fittings into the pipe. This model uses a submodel to allow you to specify the number of fittings.

FlowElem*

Submodel

Models the flow inertia in a pipe. It includes the inertia of the fluid so that the difference in pressure accelerates the flow. The FlowElem equation is based on the definition of force (Force = Mass * Acceleration). The submodel calculates the force by the pressure difference and the mass from the liquid slug in the pipe. It uses the acceleration to calculate the time-dependent flow rate. The FlowElem submodels construct one half of the Pipe model, which alternates the FlowElem submodel with the WallElem submodel to simulate water hammer along a pipe.

HP2Source

Model

Defines the flow, thermodynamic state, and composition of a feed stream. In Process mode, specify the pressure, temperature, flow, and composition of the stream. In Fluid Flow and Dynamics modes, the flow is typically calculated.

HPSink*

Model

Allows you to test the HPSource and Tube models without attaching a Channel or Shell.

HPSource

Model

Sets the conditions of the high-pressure fluid. The HPSource model is based on the Process Library Source model. Refer to the Process Library for more information.

Motor

Model

Represents the physical motor that powers rotating equipment items. Connect a Motor to a rotating equipment model, such as a Pump, to set its speed to any value between zero and the Speedref value of the rotating equipment model.

Orifice

Model

Models a flow restriction orifice (RO) device. It is based on orifice equations in Crane Technical Paper 410. It uses a curve for a square-edged orifice coefficient based on the assumption that the flow is fully turbulent.

PID

Model

Represents a Proportional-Integral-Derivative (PID) controller with integral windup protection used for pressure control. The PID model in the Transient Flow Library is the same as the PID model in the Controls Library except that it provides only Types that are suitable for the Transient Flow Library. Use this model for surge analysis.

Pipe

Model

Models a one-dimensional segmented pipe of alternating flow and wall elements. Use this model for long pipes so that you do not need to construct the pipe manually with alternating PipeFlow and PipeWall models.

PipeFlow

Model

Models the flow inertia in a pipe or the low-pressure side of a heat exchanger. This model includes the inertia of the fluid so that the difference in pressure accelerates the flow. The PipeFlow equation is based on the definition of force (Force = Mass * Acceleration). The model calculates the force by the pressure difference and the mass from the liquid slug in the pipe. It uses the acceleration to calculate the time-dependent flow rate.

PipeWall

Model

Models the fluid compressibility and pipe wall elasticity of a section of pipe. You can alternate the PipeWall and PipeFlow models to simulate water hammer in a long pipe or to represent the low-pressure supply and return piping in a heat exchanger tube rupture simulation.

Pump

Model

Uses pump performance curves to calculate pressure rise.

RD

Model

Calculates the flow of low-pressure liquid through a rupture disk. The model uses a time delay such that the disk is delayed for a few milliseconds until after the pressure exceeds the burst pressure to model the deformation of the disk.

RV

Model

Calculates the flow of low-pressure liquid through a relief valve. The model uses a force balance around the disk to calculate the disk acceleration. The flow through the relief valve is based on the disk position.

RVS

Model

Models a simplified relief valve (as compared to the RV model with a force balance around the moving disk). It assumes incompressible flow only.

Shell

Model

Models the low-pressure side of a heat exchanger. Use this model for heat exchanger tube rupture.

Sink

Model

Specifies the terminal pressure of the system. You must use the Sink model to terminate the simulation so that you can change from Process mode to Fluid Flow mode to Dynamics mode.

Source

Model

Defines the inlet boundary pressure of the system and the inlet stream properties. You can directly define the fluid properties, density, viscosity, bulk modulus, vapor pressure, and molecular weight or you can calculate them in a reference fluid state. In either the direct or Fluid-based case, the simulation feeds the properties to downstream equipment models and does not recalculate them to increase computation speed.

StandPipe

Model

Models a vertical pipe for pressure surge suppression that is open to the atmosphere. As height increases, the pressure at the base of the StandPipe model increases. We assume the StandPipe model is infinitely tall.

Suppress

Model

Models a bladder surge suppressor or hydraulic dampener. The Suppress model has a volume of compressible inert gas modeled as an ideal gas. It also includes an inlet pipe that allows fluid to enter and exit the suppressor, which compresses the gas. The volume of gas in the suppressor dampens pipeline pressure spikes.

Trans

Model

Represents a transmitter which can connect to a PID or other control model. It is the same as the Trans model from the Controls Library. Use this model for surge analysis.

Tube

Model

Calculates the flow rate in one opening of a ruptured heat exchanger tube. Typically, the high-pressure side is a gas or two phases. The Tube model is derived from the FlareLib Pipe model.

Valve

Model

Uses flow equations from the Instrument Society of America (ISA) for incompressible and compressible flow. You can use the Valve model as a manual valve if its control port is not connected. If the control port is connected to a PID or other control model, the Valve model automatically assumes the position of the controls it is connected to.

WallElem*

Submodel

Models the fluid compressibility and pipe wall elasticity of a section of pipe. You can alternate FlowElem and WallElem submodels within the Pipe model to simulate water hammer in a long pipe.