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In case of a heat exchanger, both variables are determined by the UA value of the heat exchanger, and 3 equations that apply (see further).
In case of other regime changing base circuits like a storage tank, the primary return temperature can be a design parameter chosen by the user).
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Now that we know the primary return temperature, we can calculate the primary flow.
In the example above, the primary return temperature is calculated and results in 28°C. The primary flow is also calculated and results in 0.58 m3/h
step 5
The primary power and primary diversity factor are not impacted by regime changing base circuits, this is actually obvious :
first law of thermodynamics : the power at primary and secondary side is always the same (assuming no thermal losses)
the diversity factor is a “probability of simultaneous tappings“ which is obviously not impacted by components in the network
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It is correct to state that the diversity power = diversity factor * total power It is NOT correct to state that the diversity flow = diversity factor * total flow |
Heat exchanger
In the example above , (in which the UA value of the heat exchanger is known) a system of three equations determines the primary flow and primary return temperature. In all equations, the power P is equal.
system equation at secondary side
system equation at primary
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side
heat exchanger equation in between :
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