A bit similar as for the production side, it is possible to connect multiple consumers in different ways. Besides the regular parallel emission configuration, the Hysopt Optimiser provides two different configuration possibilities.

Serial Consumer

This BC can be used to put emission units in series. In practice, this is used whenever there is an emission system that requires a hot flow temperature and that still has a sufficiently high return temperature to function as flow temperature for an emission system at low temperature.

The serial consumer BC has no parameters.

Consumer switch

This BC can be used to put emission systems in a switchable configuration.

The consumer switch BC has two parameters:

Primary regime: The temperature regime at the primary gate that is further propagated upstream during the ‘Compute design flow’ step. By default, this value is set to 75/65 °C.

Note that, as the two emission systems can be designed at different temperature regimes, the primary regime must be filled in manually by the user. The Optimiser will not propagate a temperature regime from the secondary to the primary gate during the ‘Compute design flow’ step.

Primary design heat flow: The designed heat flow at the primary gate that is further propagated upstream during the ‘Compute design flow’ step. By default, this value is set to 10 kW.

Note that, as the two emission systems can be designed at different heat flows, the primary design heat flow must be filled in manually by the user. The Optimiser will not propagate a design flow from the secondary to the primary gate during the ‘Compute design flow’ step.

Besides its parameters, the BC has two components:

Three way on-off valve: A control valve that is used to switch between the emission circuits.
Actuator: The device that helps make the physical movement of the control valve.

More information on those components can be found here: Control valves

Implementation of hybrid emission circuits in the Optimiser

This section will briefly look at the differences between the different emission circuit configurations within the Optimiser.

Parallel emission circuits

A parallel emission circuit is the most common type of end unit configuration. In the Optimiser, the parallel connection of end units is simply done by connecting the two circuits to the same node. During the ‘Compute design flows’ step, the primary design flow rate & heat power are calculated by simply adding up the design flow rates & heat power of both end units.

Serial emission circuits

A serial emission circuit is represented in the Optimiser by connecting both end units to one of the secondary gates of the ‘Serial consumer’ BC. In the example, the upper circuit is supplied first, and the circuit on the right is supplied with the return flow of the first circuit.

Note that, as this is a serial circuit, the flow rates towards both circuits will be the same. This should also be respected during the design phase of the end units. On top of that, the design flow temperature of the second circuit should be the same as the design return temperature of the first circuit.

When the end units are designed in such a way that the design flow rates, calculated during the ‘Compute design flows’ step, are not the same, the Optimiser will stop its calculations at the ‘Serial consumer BC’ and generate the following error:

To solve this, the user has to change either the design power or the design temperatures in one of the end circuits such that the design flows match.

When the end units are designed in such a way that the design supply temperature of the second circuit doesn’t match the design return temperature of the first circuit during the ‘Compute design flows’ step, the Optimiser will stop its calculations at the ‘Serial consumer BC’ and generate the following error:

To solve this, the user has to change the design temperature of either the first or second circuit until the design flow temperature of the secondary circuit matches the design return temperature of the first circuit.

When done correctly, the Optimiser will calculate the primary design heat power by simply adding up the heat power of both end units.

Switchable emission circuits

A switchable emission circuit is represented in the Optimiser by connecting both end units to one of the secondary gates of the ‘Consumer switch’ BC. The position of the three way on-off valve determines which circuit end circuit will be supplied. A proper control strategy should therefore be applied to the valve by the user.

Note that the ‘Consumer switch’ BC does not propagate temperature regimes or heat flows from the secondary to the primary gate of the circuit block. The right design parameters should be filled in by the user. If not, the Optimiser will not give an error during the ‘Compute design flows’ step.

Example of a wrong primary design. The Optimiser will detect no error.

When done correctly, the primary design heat power should be equal to the largest design heat power at the secondary gates. Note that the design powers of both gates are not added up, as the consumer switch will only provide heat flow towards one end circuit at a time.

HYSOPT wiki