Gas sensors for greenhouse measurements

Transcription

1 HTG 2020 Fresh Valley Installation Dr. Martin Paplewski Gas sensors for greenhouse measurements

2 Agenda 1. Applications for Gas sensors Which gases should be measured? Which sensor technology should be used? 2. Multi Sensor Platform Advantages and features Installed greenhouse gas sensors 3. Results and further improvements Discussion of actual data material Improvement of sensor arrangement

3 Applications C 2 H 4 CO 2 CH 4 C 2 H 4 Greenhouse gases of interest Carbon dioxide as the overall indicator for the plant grow process ( ppm target range) Methane/NO for detection of incomplete combustion or other sources of air pollution (0 100 ppm) Ethylene also submitted by incomplete combustion, but also well known plant hormone produced in nature ( ppm for ripening, <1 ppm by plant release)

4 Applications C 2 H 4 / C 2 H 4 O NO Biogases of interest Ethylenoxid as a precursor of Ethylene to detect incomplete combustion at the source before pollution enters the greenhouse (0 20 ppm) Nitric Oxide for detection of incomplete combustion or other sources of air pollution (0 100 ppm)

5 Applications Sensor requirements for greenhouse operation: low detection limit low drift with auto calibration and corrections for temperature, humidity and air pressure fast response time wide temperature range long lifetime, one by one replacement intrinsic safety competitive price alternative to analytic instruments

6 Gas Sensors Optical Sensors Uses Non Dispersive Infra-Red (NIR) light for the absorption in specific molecular bands of CO2 and CH4. long lifetime of > 4 years very robust and stable internal EEPROM for calibration data very sensitive and specific for the target gas Optimal use inside Greenhouses at higher humidity levels

7 Electrochemical Sensors Gas Sensors Uses a specific, but irreversible chemical REDOX reaction for gas detection. limited lifetime of ~3 years consumes electrolyte for chemical reaction available for many gases C 2 H 4, C 2 H 4 O, NO x, SO x low cross-sensitivity due to special filters requires startup and equilibration time of some hours requires external calibration and configuration Optimal use for bypass measurements at biogas reactors

8 Sensor Platform - Mainboard holds up to four different type of gas sensor modules integrated T-, P- and %RH sensor for auto calibration integrated 32-bit CPU for real time data acquisition + SD-card slot for data storage and data logging + USB, LAN, WLAN and 868 MHz data communication link + eight high power switching outputs + integrated flow controller for gas sample flow + low power consumption and battery operation possible

9 Sensor Platform Sensor PCB available for all gas sensor technologies integrated EEPROM for calibration data + programmable 16-bit A/D converter + fast sampling rate + integrated temperature sensor for drift compensation + small package size

10 Sensor Installation 1. Ethylenoxide + Ag Catalyst Electro Chemical Gas Sensor

11 2. Nitric Oxide (NO) Electro Chemical Gas Sensor Sensor Installation

12 3. Carbon dioxide (CO2) NIR Gas Sensor Sensor Installation

13 Sensor Data

14 Sensor Data

15 Climacteric fruit ripening A rapid rise in the respiration rate during the initiating ripening process => climacteric effect Triggered by low ethylene concentrations (<1ppm) which are difficult to measure Could be controlled over the respiration rate with multiple CO 2 sensors by calculating a difference signal Climacteric Non Climacteric Apple Cherry Banana Citrus Mango Strawberry Olive Pineapple Tomato Watermelon

16 Improvements Greenhouse Unique 4-20 ma transmitter Sensors with long-term stability, high sensitivity and selectivity Biogas Reactor Ethylene and Nitric Oxide sensor installation in stream bypass

17 The ethylene cell-membrane receptor protein includes a copper cofactor Future trends copy the nature

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