System Properties

You can set properties for the whole system, for the inlets and outlets, and also for the circuit elements.

Circuit Properties

The circuit properties include the name of the circuit, the gravity orientation, and the calculation method for minor losses.

Gravity

The gravity vector is required to calculate elevation differences in the network, as they can have a significant impact on the flow.

Minor Losses

Minor losses depend on various factors such as sudden changes in the pipe diameter, bending angles, or valves.

There are three calculation methods for minor losses:

• Calculate except when K factor specified

  This is the default method. Minor losses are calculated automatically unless a K factor has been defined. If k factors have been supplied, Dalton uses them to calculate the minor losses.

• Don't calculate (use specified K factors)

  If this option is selected, the provided K factors are used to calculate minor losses.

• Calculate & add them to the specified values

  If this option is selected, minor losses are calculated and added to the specified K factors.

Boundary Conditions

A boundary node is a node that is connected to one element. You must specify boundary conditions for at least one inlet and one outlet.

Type

In a circuit, there are two types of boundary nodes: inlets and outlets. To run the simulation, the circuit must contain at least one inlet and one outlet.

Constraint / Value

Pressure, velocity, mass flow rate and Reynolds number are typical boundary conditions.

When solving pipe networks, at least one boundary condition in the network needs to be a pressure boundary condition.

Fluid

The fluid density may vary in response to changes in the fluid temperature and pressure.

You can use the default fluid temperature, or specify a temperature.

Element Properties

Elements are assigned a set of properties which depends on their type.

Type

There are four types of elements in a circuit: Pipes and connectors, Pumps, Valves, and Generic Losses.

Energy Type / Energy Value

The energy type can depend on the element or on the heat flux.

Diameter (Pipes, connectors, valves)

The diameter and cross sectional area of the pipe or duct are required for the pressure drop calculation.

Material / Roughness (Pipes, connectors, valves)

The friction factor depends on the Reynolds number in the fluid and the relative roughness of the pipe or duct material.

The roughness depends on the type of material used for the element.

K factor (Pipes, connectors, valves)

The K factor is useful for calculating minor losses and the performance of valves.

Wetted pe. (Pipes, connectors, valves)

The wetted perimeter and the cross sectional area are required in order to calculate the hydraulic diameter of the element.

Curve (Pumps and Generic Loss)

The pump curve represents the pressure rise flow rate relationship through the pump or fan.

This value is used to define the efficiency at which the pump is operating at.

The Generic losses vary with the pipe diameter, surface roughness, Reynolds number and the geometry of the design.