Azione B1: Definizione delle specifiche tecniche e sviluppo dei due prototipi
Durata: Giugno 2012 - Marzo 2013
Scopo: Scopo di questa azione è la progettazione e realizzazione dei due prototipi: una stazione di misura per il monitoraggio in continuo della variabilità temporale delle emissioni di N2O, CO2 e CH4 dal suolo e uno strumento trasportabile per la rilevazione della loro variabilità spaziale.
Partner Responsabile: I due prototipi verranno progettati e realizzati dal team di WEST Systems.
Risultati attesi: Il principale risultato atteso di questa azione è la progettazione e realizzazione dei due prototipi, corredati di manuale d'uso.
Stato dei lavori: La realizzazione dello strumento trasportabile è stata completata a Giugno 2013. L'assemblaggio della stazione di monitoraggio continuo è stato completato a Maggio 2014.
Action B1: Definition of the technical specifications and implementation of the two prototipes
Duration: July 2012 - March 2013
This action is addressed to plan and implement the two prototypes for measuring N2O fluxes.
The portable prototype, includes:
(i) the N2O Analyzer and CO2 Analyzer;
(ii) the Accumulation Chamber, which is equipped with a suitable chamber base, a gas mixing device, a port for pressure equilibration with the atmosphere, and a septum for gas sampling;
(iii) the Local Processing Unit (LPU), representing an interface among the Personal Digital Assistant, the two gas analyzers, and the Control Unit;
(iv) the Control Unit, which is a peripheral of the LPU and acquires soil temperature and moisture data from local sensors, and controls the gas flow in the sampling line;
(v) the PDA, which is equipped with a GPS and is connected to the LPU via wireless, through either a Bluetooth or a "WiFi" (IEEE 802.11) protocol.
As already recalled above, the prototype will be able to host each one of the two N2O analyzers acquired in the project. Several accumulation chambers, with different height and base area, will be designed and implemented based on the experience gathered at the INRA Research Centre of Versailles-Grignon and in the pertinent scientific literature (e.g., Rochette and Eriksen-Hamel, 2007).
The LPU will consist of either a small embedded computer, positioned on the accumulation chamber, or a microcontroller. Functioning of the LPU requires development of a specific software, for management of the N2O-A and CO2-A, acquisition of data collected by soil sensors, and control of the pump and mixing device. The LPU, through this software, will continuously monitor the battery level and compute the residual autonomy of the whole system.
Thanks to the wireless connection for device control and data acquisition, only one operator will enter the field, minimizing the impact on the crops.
One of the main challenges for the use of the portable prototype is represented by a light tracked vehicle, powered by an electrical engine and battery-sustained, allowing to move the prototype in the field, as the size and weight of this device make impossible to carry it on the shoulders of an operator. The latter solution is instead possible for the measuring systems of CO2, CH4, H2S, and VOC fluxes, which were developed by West Systems in previous years. The chassis of the tracked vehicle must be high enough and the track distance wide enough to avoid crop damaging. The portable prototype will be planned and implemented to be fully integrated with the vehicle, in that the vehicle must has a suitable platform where to install the prototype and could also power the prototype through its own batteries. Nevertheless, the two items must be easily disassembled as gas analyzers must be exchangeable between the two prototypes.
The station prototype, which is made up of the following items:
(i) the N2O Analyzer and CO2 Analyzer, similar to the portable prototype;
(ii) a series of accumulation chambers (AC), at least four, each one equipped with a suitable chamber base, a gas mixing device, a port for pressure equilibration with the atmosphere, and a septum for gas sampling; a suitable device that moves up and down each inverted chamber is required to perform continuous monitoring of gas fluxes;
(iii) a multiplexer-control unit (MCU), which carries out switching of the different accumulation chambers, allowing to measure gas fluxes in four distinct positions of the surveyed field; it also acquires soil temperature and moisture data from local sensors and controls the gas flow in the sampling line;
(iv) the Local Processing Unit (LPU), autonomously controlling the proper functioning of the station and communicating with a remote control center via UMTS-internet connection;
(v) a remote control center for data acquisition and visualization, check of the instruments, including diagnostics of some parts of the station (not represented in Figure 2).
The system will be powered through the power grid at 230 V AC, which is available at both selected field sites of the Interdipartimental Centre for Agro-Ecological Research E. Avanzi (CIRAA) and the Cesa Research Centre for Agricultural Technologies and Extension Services (CATES). A shelter, apt to work under rough field conditions, will be designed for hosting the instrumentation mentioned above, as well as a back-up battery unit, which will feed the system in case of short black-outs.
All these activities will be performed at the West Systems headquarters in Pontedera (Pisa, Italy) and will be completed in 9 months approximately.
Study of spatial variations in N2O emissions requires transportation of the prototype within the area of interest. To attain a good sensitivity, a bulky and rather heavy detector must be used. Consequently a small tractor is needed for its transport in the field. The tractor, will be powered by electrical engines, working without emission of fumes that could interfere with the measurements. The tractor will be equipped by rechargeable batteries to assure extended range and a sufficiently long running time. The vehicle batteries will be used also to power supply the instrumentation during field-work. This type of vehicle has been chosen as it works on all ground types and enters into field crops .Where field crops prevent access near measurement points, tractor and instrumentation will be positioned as close as possible to the sample area and the accumulation chamber will be connected to the instrumentation by means of small internal diameter (1.2 – 2 mm) stainless steel or PTFE pipes. This technique, already experimented by West Systems and INRA, allows one to obtain good results even using pipes of total length of some tens of meters. The vehicle will be equipped with a case to host the instrumentation, the LPU local processing unit, the power supply/inverter system that will take power from traction batteries. The case will be designed both to protect the instrument from the influence of weather conditions and to mitigate the effects of vibration and acceleration due to transport. The versatility and high load capacity of this type of vehicles will make easy the transport of instruments and related equipment.
The main expected outputs of this action are the two prototypes, as well as their designs and technical specifications, namely:
(i) The portable prototype, comprising the accumulation chamber instrument and the light tracked vehicle for displacing it in the field.
(ii) The station prototype, for continuous monitoring of N2O fluxes in a fixed location.
Other products of action B1 are the operative user’s manuals (one for each prototype), that will be further implemented during the subsequent actions.