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First of all, we make a distinction between the calculations within one dwelling, and the calculations over multiple dwellings.
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Within Single dwelling
Step 1 : recalculation of the tapflows
Step 4 : aggregation of the DHW flow/power with the CH flow/power at CH side
Example (outdated)
Consider a system of appartments, each having a satellite heat exchanger for instantaneous domestic hot water production. To keep the example simple, we assume each appartment to have a DHW heat load of 40kW with a temperature regime of 70°C / 30°C, and a 15kW central heating heat load, with a temperature regime of 70°C / 60°C. This results in following flow rates in relation to n. We use M for total mass flow.
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Q CH (kW) | M CH (kg/s) | Q DHW (kW) | M DHW (kg/s) | m DHW (kg/s) | f (-) | m total (kg/s) | Q total (kW) | m sizing (kg/s) | Q sizing (kW) | T return (°C) | |
|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 15 | 0.36 | 40 | 0.24 | 0.17 | 0.72 | 0.27 | 33 | 0.36 | 33 | 48.0 |
2 | 30 | 0.72 | 80 | 0.48 | 0.33 | 0.69 | 0.55 | 64 | 0.72 | 64 | 48.5 |
3 | 45 | 1.08 | 120 | 0.72 | 0.43 | 0.60 | 0.86 | 90 | 1.08 | 90 | 50.0 |
4 | 60 | 1.43 | 160 | 0.96 | 0.51 | 0.53 | 1.18 | 113 | 1.43 | 113 | 51.1 |
5 | 75 | 1.79 | 200 | 1.19 | 0.57 | 0.48 | 1.51 | 135 | 1.79 | 135 | 52.0 |
6 | 90 | 2.15 | 240 | 1.43 | 0.62 | 0.43 | 1.84 | 155 | 2.15 | 155 | 52.8 |
7 | 105 | 2.51 | 280 | 1.67 | 0.67 | 0.40 | 2.17 | 175 | 2.51 | 175 | 53.3 |
8 | 120 | 2.87 | 320 | 1.91 | 0.71 | 0.37 | 2.51 | 194 | 2.87 | 194 | 53.8 |
9 | 135 | 3.23 | 360 | 2.15 | 0.75 | 0.35 | 2.85 | 213 | 3.23 | 213 | 54.2 |
10 | 150 | 3.58 | 400 | 2.39 | 0.78 | 0.33 | 3.19 | 232 | 3.58 | 232 | 54.5 |
Graphs (outdated)
To clarify things further, we include some graphs for the combined flow rates and power. These graphs are for increasing domestic hot water power / flow rates at 70° / 30°C with a fixed power of 50kW heating at 70° / 60°C.
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