The thermal stores in Hysopt can be used for central heating (CH) or domestic hot water (DHW).
Central heating storage units
Direct, indirect and electrical
The central heating storage units can be divided into three types: Direct, Indirect, and Electrical.
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Besides the visualized base circuits (BCs) above, more BCs are available combining different types or allowing multiple connection possibilities.
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Two-pipe and three-pipe storage tanks
In addition to thermal storage tanks with four (or more) pipe connections, the Hysopt library also includes two buffer vessels (BCs) with respectively three and two pipe connections (see figure below). All variants in Hysopt provide hydraulic separation, which is why the two- and three-pipe tanks feature wide connections at both the top and bottom.
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Depending on the designer’s preferences and the specific application, two- or three-pipe storage tanks can offer certain advantages. For example, these configurations allow supply water from the primary side to be delivered directly to the secondary side without passing through the tank. This is particularly useful during start-up, as it ensures the secondary side receives sufficiently high flow temperatures without the need to partially charge the buffer.
The three-pipe variant includes a direct connection at the top for supply, while the bottom features two connections. This setup ensures that the return water from the secondary side passes through the buffer before returning to the production units, which helps to mitigate highly fluctuating temperature swings in the return water to more stabilised return temperatures towards the primary side.
Additional variants
Furthermore, there are 3 more exotic thermal storage units.
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The third one is a thermal store in the supply pipe. In contrast to all other stores, this one only has a capacitance as design parameter. Its main purpose is to put thermal mass into the system.
Design parameters
The parameters needed for the design of the system are mostly the design heat flow and the temperature regime.
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Remark: For units with electrical resistance, the design heat flow is needed for simulation not for design since there is no primary side to propagate to. The design heat flow is used in simulation to specify the amount of thermal power going into the thermal store. Seeing as it is a production unit as well, a control signal is needed to activate and/or modulate the thermal power delivered by the electric resistance.
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Domestic hot water
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Domestic hot water store units are similar to the central heating store units, except that they no longer have a secondary gate. Instead, a tap profile from the control library must be attached in order to generate a load towards the heating store. More information on a tap profile can be found here: Tap profile generators As there is no longer a circuit downstream of the BC, the design heat flow & temperature regime from the BC’s parameters are propagated further upstream, even if those values aren’t locked.
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