[TRNSYS-users] Type 71 Evacuated tube collector - Control vs. overheating

[maverickxxx1991 <maverickxxx1991@googlemail.com>]

Hi,

I’m using 2 type 71 and I get temperature up to 400°C if I use a control. I have 3 Controllers of type 2b:

1st looks if temperature of collector is higher than secondary inlet of heat exchanger with hysteresis (7K and 4K)
2nd looks for storage temperature (<95°C with hysteresis again „On“ at 90°C)
3rd is for collector protection (collector temperature <110°C with hysteresis again „On“ at 95°C)

The collector values are (0.688, 0.583, 0.003) (last in W/(m^2*K) and W/(m^2*K^2)).
Test condition flow rate 0.02 kg/(s*m^2).
2x86 m^2 area, no. in series 1, flow rate 2600 kg/hr.

So if the controls says out the temperature in the collectors rise up to 400°C. Is it normal? How can I fix it? I even wondering about the temperatures rising so fast also in winter from 15 to 80°C.

Thanks for help!
maverickxxx