ErfGoed’s Airflow system offers opportunities for energy savings as well as achieving a significantly lower temperature between the crops. The latter benefits growth and quality. This is evident from measurements and tests carried out with the Airflow system recently. Although the results are positive and the system appears promising, there are still many questions, and the company says follow-up research is needed.
The new Airflow system consists of an ebb-and-flow floor, which is heated and cooled through hoses under the floor. In addition, air is introduced through distribution tubes in the floor to heat or cool the air around the crop. These tubes are fitted with holes, allowing the air to distribute through the floor, which has a porous layer. The combination of the heating and cooling tubes and the insertion of air makes the system unique.
ErfGoed carried out extensive trials of the new system recently. This took place at its site in Moerkapelle, in a crop of Sarcococca. Adviser Leo de Rijke of De Rijke Techniek was closely involved and carried out various measurements and analyses. “We measured both pot, floor, and room temperatures,” he says. “We did this in a department with an innovative floor and in a ‘normal’ department, with a regular ebb and flow floor from ErfGoed. All other conditions being equal, the added value of the Airflow floor was very clearly visible.”
Making better use of low-grade heat
Part of the study involved mapping the effects of heating through the Airflow floor. Here, via the hoses, low-grade heat of 35 degrees was supplied. Air was also introduced into the floor, which was distributed through the floor via a special system. “We saw that by introducing the air, we were able to cool the low-grade heat back to a temperature of 22 degrees. Without input from the air, the return temperature was 27 degrees. Specifically, this means that you can use the low-grade heat much better this way. In other words, with the Airflow system, you get more efficiency from low-grade heat. That has everything to do with the fact that the release capacity of the floor is increased by introducing the air.”
According to De Rijke, this fact offers opportunities for energy saving and can be of interest to entrepreneurs working with geothermal heat or heat pumps, among others. “We have now introduced the low-grade heat via the boiler for the trial, but you can, of course, also use geothermal heat or heat from a heat pump. Then, as an entrepreneur, you can either choose to cool the heat back as far as possible or lower the supply temperature. That way, you need less energy to keep your greenhouse at the right temperature. How much exactly, we need to find out. But this does result in a better efficiency of a heat pump or geothermal heat source.”
Cooler on hot days
In addition, during the past period, extensive tests were carried out on cooling the Airflow floor via the hoses in combination with introducing cold air. This proved to have a clear added value on hot days, indicates the consultant. “We saw that the temperature between the crop in the section with the Airflow system was, on average, about five degrees lower on these days than in the section with the regular ErfGoedVloer. This is due to the combo of introducing cold water through the hoses and cold air and the fact that you bring the cold exactly where you want it.”
The lower temperature has a clear added value for crop growth, according to Cor Bremmer, Commercial Director at ErfGoed. “A temperature between 20 and 30 degrees is most optimal for crops in terms of growth. The RH went up because the dry airflow absorbed moisture from the floor. And this makes the stomata open, which promotes photosynthesis. In addition, air movement is beneficial for plant growth, and we saw that the microclimate around the plant improved.”
So, both heating and cooling with the AirFlow system appear to have clear added value. According to De Rijke, which variant is most interesting depends on a grower’s specific business situation and their location. “It makes sense that cooling with the AirFlow system is probably especially interesting for entrepreneurs in warmer areas. But these are issues we will look at further in follow-up trials. There are still many questions anyway, such as whether the investment in the system can be calculated around and, if so, in what time frame. But it is clear that the Airflow system offers plenty of potential.” New trials will soon be set up at ErfGoed and also among a number of customers in the field.
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2751 GH Moerkapelle