8 Function of the check valves [Expert]
2016/05
997655910x-mub-en
–
V07
25
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The density of the solar fluid decreases with rising temperature. In high installations with large
temperature differences, the difference in density will cause gravity circulation. This circulation
can lead to a cooling down of the storage tank.
Calculation example: Δp = Δρ * g * h
Collector temperature: 5 °C
Density solar fluid ρ
1
= 1042 kg/m³
Storage tank temperature: 67 °C
Density of the solar fluid ρ
2
= 1002.5 kg/m³
Δρ = ρ
1
- ρ
2
= 39.5 kg/m³
g = 9.81 m/s²
Installation height h = 10 m
Δp = 3875 Pa = 395 mm wc
The two check valves per storage tank circuit in the station (2 x 200 mm wc) are sufficient for an
installation height of 10 m and a temperature difference between the collector and the tank of up
to 62 K.
