Christophe wrote:
If this greenhouse does not heat more than 45 ° C in summer, it means that the losses (by conduction, convection and radiation from the greenhouse) are balanced with solar radiation ...thus at 45 ° C one can say that the sun "does not bring" any more "useful" energy inside the greenhouse since the T ° stagnates ...
However if we lower this T °, we can think that the sun will continue to bring calories in the greenhouse ...
This is not good? : mrgreen:
For me, you are still only half there!
a) letting the greenhouse cool down under the outside temp is, in this case, an absurdity, since your heat pump will be less efficient! So to think that then solar energy is better captured is true, but without interest!
b) with regard to the flows themselves and the greenhouse balance:
1) at a given time, the solar energy that enters the greenhouse depends on the solar intensity, the nature and cleanliness of the windows ...
2) Out of the heat pump, the radiation linked to the temperature of the ground, the wall, the air ... radiation at a frequency other than solar radiation at 'sharp (it is very very infrared)
3) It enters or leaves by conduction, air current, energy depending on whether the external temp is lower or higher ...
Normally, outside the heat pump, the results are positive when there is sunlight: a lot of "high temperature" radiation coming in; this captured energy is greater than the sum "losses by conduction + losses by low temperature radiation"; the greenhouse effect, that's it, based on the observation that the frequency of the "input" and "output" radiations is not the same, and that the window retains part of the second, while it leaves enter first ...
But with the temperature rising in the greenhouse, the losses increase, and we always arrive at a balance. In a closed greenhouse, even in the middle of summer, we never reached the boil, even if we can make plants burst !!! It is that the "entries" remain stable, but the "exits" increase
So yes, with your CAP:
a) either you just manage to align the external and internal temp; you eliminate the losses by conduction and by radiation "low temperature" (the incoming BT radiation compensates the outgoing BT radiation); all "input" solar energy is captured by the heat pump ...
b) or you can only lower the temp in the greenhouse (it is 10 ° external, with the sun without PAC it would be 27; with PAC, it is 14): there, in fact, you will have reduced the losses by conduction and by radiation - compared to a greenhouse without PAC -, thus you auars improved the output of your greenhouse; and with that, that of your cap ...
c) either your heat pump cools your greenhouse under the external temperature, and we have already seen that this is absurd; the "infinite reservoir of air at the external temperature" is more "profitable" ... Even if your greenhouse captures even better solar energy + conduction + LV radiation !!!
So I put 50/50. You were both a little right.
