Boundaries for heat transfer

A boundary is a surface for heat transfer. It is represented on the screen as a line, or rather a flat rectangle with an arrow in the middle. The menu command View|Heat transfer boundaries must be checked to see the boundaries. The arrows are only visible if View|Arrows is checked. The colour of a boundary is green, unless two component are attached at the boundary. Then the colour is blue. If the boundary is marked (has focus), the colour is black.

There are a number of component models (always or optionally) that are equipped with boundaries for heat transfer. The model 1D heat source/sink has at least two boundaries, the external boundaries. In addition it may have one boundary for each of the layers constituting the one-dimensional multi-layered structure. A layer boundary is activated in the layer dialogue. The Temperature zone component model can have an arbitrary number of boundaries equal to the number of corners of the polygon constituting the component.

A component boundary is only active if attached to the boundary of another component. Boundaries are attached to each other by first marking the boundary of the component to be moved (turning the boundary black) and then marking the boundary of the component not to be moved at the same time holding down the Control key. Mark a boundary by clicking close to the boundary arrow in the middle. If instead you click near the boundary ends, you will normally mark the component owning the boundary.

If two boundaries are of the same kind, e.g. convection boundary conditions or temperature boundary conditions, the two boundaries will not actually attach when joined, but form a "twin set". In this case, the surface temperature of one will be the ambient temperature of the other, and opposite.

After an attachment, the components cannot move. You detach a component by detaching all its boundaries. To detach a boundary, just hold down the Shift key while clicking it. You will see the detachment effect as the boundary turns from blue to green.

It is possible to perform an action on the plant that makes two attached components separated position-wise. A detach and re-attach is then necessary to re-join the components at their common boundary.

If, after attaching two components, one or both of the basis components holding the components data change in size, the components are detached from each other. Then repeat the attachment. If suddenly a boundary seems to be adiabatic, check to see if it is still attached (i.e. blue).

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