|Phase Change||What can you expect?||Protection limits||Guidelines for use||Improving fruit set||Agrofrost vs. science||Wet and dry temperature|
Agrofrost versus Science
Frost protection with our Frostbuster and FrostGuard is a new and revolutionary system. Since 2001, when the Frostbuster was introduced on the European market, tests has been done and results have been analyzed. It was easy to found out that the machine was very effective, but it was difficult to find out why it was so effective.
Most scientists first look at the energy input of our system. Based on that, they conclude that our system cannot work. This is because all other frost protection systems are based on raising the temperature above the critical values. And this demands a huge input of energy. Because we only use a fraction of that energy, most people will say that the energy input is too low and that it’s impossible to create a good frost protection with such little energy input.
But practice has proven that these people are wrong. So there must be another explanation why our systems is so effective, using such low energy input.
Let’s take a look at some facts and experiences.
- The hot air stream of our machines passes and provides energy where it’s needed: on the flowers and buds.
- The outlets of the machines make sure that the air stream remains horizontal as far as possible.
- Air with a high humidity has more latent heath (=energy) than air with a low humidity (at the same temperature).
- Air with a high humidity transfers more heath (=energy) to its surroundings than dryer air.
- Wet flowers freeze easier than dry flowers. So if we can dry the atmosphere, damages will be less. (a wet flower freezes at -2°C, a dry flower freezes at -5 °C)
Experiences from tests and experiences from our customers
- It’s very important to start the machines before the wet temperature becomes negative.
- It’s very important to start the machines before flowers and leaves are covered with hoarfrost.
- Where we use our machines, the forming of hoarfrost in the protected orchard is less compared to not protected areas.
- Contradiction 1: it’s necessary to pass with the machines on the same spot with intervals between 7 and 10 minutes. In this way, we create a temperature fluctuation. At every passage of the machine, the temperature rises and drops again after a few minutes. This fluctuation is important. We have done tests, passing every 2 to 3 minutes on the same spot, so putting in 3 times the energy, and avoiding the temperature to drop between passages. So there was no fluctuation. Result: the flowers were not protected as good as passing every 10 minutes. This was also for us a complete surprise, but practice showed very clearly that the results were much better if the temperature could go down between 2 passages. Why? We will see this later.
- Contradiction 2: normally, the risk of damages due to frost will be greater when air humidity is high. When we use our machines, we see that the results are better when the humidity is high and get worse when humidity gets very low. So, in general, the bigger the risk, the better our machines perform.
- Contradiction 3: tests done in the south of France has shown that during the use of the Frostbuster, while the instantaneous temperature becomes lower than the average temperature of the 30 previous minutes and of the next 30 minutes, the air humidity of the ambient air drops at the same time, where it normally should rise. (See article of Jean-François Berthoumieu)
Based on all above facts, conclusions, tests and experiences, we have found out what gives us the good results.
The forming of hoarfrost liberates energy. The transformation of vapor into hoarfrost gives energy. This energy is transferred to its surroundings, in this case the surrounding air but above all into the leaves and flowers themselves. The warm air stream of our machines, that passes every 7 to 10 minutes, gives energy to the ice. A part of the ice evaporates. After the surrounding air has cooled down again, some new rhyme will be formed, giving again new energy to the flowers. This explains why we need the temperature fluctuation.