Spraying can become expensive, especially if you do not target the crop precisely. For this reason, a research group consisting of the Joint Lectureship Water Technology of NHL University and Van Hall Larenstein, Nairobi University (Kenya), Wetsus and Centre of Expertise Water Technology (CEW), has managed to predict accurately and to influence the characteristics of a spray haze that was created with a spray nozzle and an electrical current. With the acquired knowledge, various processes can be executed more exact and more efficiently. For example, the agricultural and horticultural sector can use the technique to apply crop protection products very precisely to crops. As a result, none or only a minimal amount of the products will end up in the environment.
Liquids can be atomized in various ways. In this case it is about atomization by using a spray head (thin tube) and electrical current. The formed droplets have an electric charge. This way, the effect of the conical shaped spray occurs, which, for example, also is produced by a plant sprayer. For a long time it was unclear how it is possible that the droplets do not all go in the same direction. The research group in Leeuwarden discovered that this has to do with the manner in which the droplets deform.
EHDA
The cone can also be influenced by increasing or decreasing the pressure or by enlarging or reducing the nozzle opening. Disadvantages of this are lesser control and the need for a heavy compressor. By using electrical current, the direction of the droplets can be influenced very accurately, it is possible to work with much smaller droplets and the system can be kept very compact and lightweight. An AAA battery can already provide sufficient current. For example, plant protection products can be applied to crops very efficiently by drones. Atomization induced by electricity is called electro-hydro-dynamic atomization (EHDA) or electro spraying.
Symposium
The EHDA research group that conducted the research is unique in the Netherlands, and in Europe there are only five similar research groups. In January 2018 the Dutch group in Leeuwarden intends to organize an international symposium on this subject. More information will be available soon on the websites of the partners.
The research was carried out on behalf of and with funding from the Centre of Expertise Water Technology (CEW) in Leeuwarden and with funding from the Dutch Waterhelp and the International Science Program (ISP) from Sweden, through its physics program at the University of Nairobi. Special thanks goes to Van Hall Larenstein and the Water Application Centre (WAC) in Leeuwarden for making the research facilities available.
An extensive article about the research can be found in Elsevier Journal of Electrostatics (abstract free access, full article via login or purchase).
Source: CEW