Patent ID: 12222341

DETAILED DESCRIPTION OF AN EXAMPLE EMBODIMENT

Referring to the drawings there is shown an embodiment of gas monitoring system generally indicated at10. The architecture of one ripening monitor system10is shown schematically inFIG.1, and the structural details of each of the technical components in the architecture are shown inFIGS.2,3,4,5, and6. Another embodiment of ripening monitor system is shown at110inFIG.7. Like numerals on that Figure denote parts like other embodiments, for efficiency of description.

Output of a target gas sensor of the system is shown inFIG.8, and an example of a conversion algorithm based on a selected concentration is shown in graphical form inFIG.9.FIGS.10to14show correction of results based on the amount of one collateral gas, it being carbon monoxide.

InFIG.1, there is shown a schematic diagram of a gas monitoring system generally indicated as10. There is shown a conditioning unit15, a pump8, a concentrator30, a second gas pump108, a second conditioner115, a sensor module44and a main controller25. These are described in detail below, sometimes overlapping withFIG.7and the flowcharts inFIGS.14,15and17.

Conditioner Module

The conditioner module is described herein, but it is to be understood that it is an optional feature of the technology.

Control of the gas sample air temperature, humidity and pressure provides the advantage of preventing condensation (that may affect gas sensor response downstream), as well as reducing the measurement variables to provide a more accurate gas component reading on a target gas sensor.

To that end, it can be seen that the system10provides an inlet12for receiving a gas sample from either a bottle of purified aerosolized or gaseous compound or mixture or from the environment in a chamber such as the interior of a room, building, toilet cubicle, or ambient atmosphere, shipping container or trucking container or refrigerator or produce storage room or cool room, or from a combination of the above (all not shown). This received gas sample is conditioned in one or two conditioner modules described below, and analyzed downstream of those conditioner modules to assess the concentration of the target gas.

The inlet12is in fluid communication with a conditioner module15, a flow control module17and/or pump8, depending on the embodiment being discussed. Any one of those elements may include a valve11connected to the inlet12, and one of a wide variety of mechanical pumps8capable of moving the gas sample through the system at a controlled rate, with or without a regulator (not shown). One type of pump8contemplated is a peristaltic pump, and another type of pump contemplated is a piston pump. Other types of pump8are contemplated as being of utility in the system include diaphragmatic pumps, and balloon pumps, screw pumps and others that can transfer gas from one place to another in a controlled fashion.

The conditioning module15includes a tube or chamber4into which a sample gas is introduced for conditioning.FIG.2shows one possible embodiment of the conditioning module15.

The conditioning module15further includes a temperature modulation module13disposed in the walls of the tube or chamber. The temperature modulation module includes a heater element18, and a Peltier cooler19.

There is an exhaust outlet5disposed in the conditioning module chamber4to remove gas. There is also a drain3for removal of water and excess moisture and/or ice. The exhaust outlet5and drain3may be provided adjacent a valve52and2.

The temperature modulation module13further includes a sensor module16which includes a temperature sensor20, a humidity sensor22, a flow sensor14, pressure sensor62and which also may include an agitator (not shown) to facilitate the mixing of the gas undergoing pre-conditioning.

In operation, the conditioner, which is connected to the main controller25, is caused by the main controller25to actuate the Peltier cooler19to freeze the water in the sample gas in the chamber4to reduce the humidity, and then warming at least a portion of the walls of the chamber4by actuation of the heating elements18and opening valve2as part of a defrost cycle to drain the water from the conditioner module15.

Main Controller

There is provided a main controller25for, among other things, controlling the conditioning of the sample gas. The main controller25includes a microcontroller, in one form being a 32-bit ARM microprocessor, with analogue or digital inputs, and for conditioning the sample gas it is configured to interface with the sensor module16and the temperature modulation module13and the flow control module17, or in some embodiments, pump8.

Data connections are made between the sensor module16, the temperature modulation module13, the flow control module17, or pump8, and the main controller25. The data connections may also be wireless or optical or indeed any suitable connections for sending data.

One of the other tasks of the main controller25is to control the temperature and humidity in the conditioning module15. In operation, data from the sensor module16is provided to the conditioning controller25, and corrections may be made to final gas component readings to account for gas conditions sensed by the sensor module16.

Hoses

Between the conditioning module15and other components described herein, there are gas transport hoses27connected with barbed attachments and O-rings (not shown) so as to transport the gas and aerosolized compounds and mixtures.

The transport hoses27connect so as to transfer the sample gas from the conditioning module15to a concentrator module30which is identified on the Figures (at leastFIGS.1and2), downstream from the conditioning module15.

Concentrator Module

A concentrator module30shown as part of the system10inFIG.1and in detail inFIG.3, has a gas chamber33configured to receive the sample gas from the conditioning module15through inlet9. The concentrator module30further includes a heater32, a chiller31, and a temperature, humidity and pressure sensor module34. Inside the gas chamber33is provided a separator35in the form of a gas adsorption unit36, being activated carbon.

The concentrator unit30is configured to receive the gas sample (conditioned or not, depending on the embodiment being discussed) through the inlet9, such that in operation, a gas component of interest, in this case, ethylene, can be adsorbed in the activated carbon of the separator35as part of an adsorption process.

In operation, the amount of adsorbed target gas component, (related to the concentration factor of the system), may be modified by varying the mass flow of the gas sample that passes over the activated carbon36by means of the main controller25and flow controller17or pump8, or by the heat, humidity and other conditions in the conditioner15. Once a selected mass of the sample gas has passed over the activated carbon in the separator35, the controller25causes the inlet9to close, and/or the inlet valve81to close, and then heater32, configured to heat the activated carbon in the separator35, heats the activated carbon to break the bond of the adsorbed target gas, which results in a gas concentration effect within the concentrator unit30. This is referred to as a decanting or release phase.

The heater32is in the form of a temperature controlled outer layer or block37in which there is disposed an embedded heating element51, a cooling element53and a temperature sensor52. The cooling element is a Peltier element54. As with the conditioning module15, data connections are made between the main controller25and temperature sensors34and the heater32. The main controller25is configured to vary electrical power supplied to the heater32such that the activated carbon can be maintained at a preferred temperature during the gas release phase. The main controller25is also configured to vary electrical power supplied to the chiller31, which is done after the gas release phase to prepare for another adsorption cycle.

The heater's temperature is configured to be controlled during both adsorption and release phases of the concentration process. Temperature control of the carbon during the adsorption phase is beneficial as the gas sample adsorption rates can be impacted by temperature and humidity, and control of such will increase the accuracy of the system.

Corrections may be made to gas readings at the end of the detection process, described below, to account for changes in adsorption or release rates due to sensed gas conditions in the conditioning module15or in the concentrating module30, or in the secondary conditioning module115.

The flow controller17or pump8(in another embodiment) is controlled with influence from the readings from a gas flow sensor14; this provides facility for more accurate control of gas flow rates in the system and improves overall target gas sensing accuracy.

In an embodiment that is not shown, a flow controller may be placed downstream of the concentrator unit or sensor unit. Mass flow may also be varied by changes to the volumetric flow rate of the flow controller17or by the pump8. Changes to mass flow may be obtained by increasing the duration of phases, such as the number of seconds of the adsorption phase or release phase.

A check valve is in fluid communication with the inlet so that gas samples may only flow one way through the system, thus preventing contamination of results by double-measuring the same sample of gas.

In one embodiment the separation could include CO2 scrubbing by using a membrane and in that embodiment the store would be a separate storage chamber (not shown) to the side or end or at least adjacent to the chamber33.

Sensor Conditioning Module

A sensor conditioning module115which is similar to the conditioning module15is provided in the embodiment shown inFIG.1to facilitate providing the sensors in the analysis module with sample gas within selected parameters for more accurate sample gas component readings.

In this embodiment, when provided and in use, the sensor conditioning module, which looks similar to conditioning module15, receives target gas from the release or decanting phase from the concentrator30. In use, the sensor conditioning module115is instructed by the main controller25to cool the sample gas down to a selected temperature by actuating Peltier elements, so that the target gas sensor reads the gas in its most sensitive zone.

The sensor conditioning module115also includes a pump108to transfer the conditioned sample gas to the analysis module44.

As with the conditioning module15, there is provided an exhaust outlet and a drain outlet for water and moisture and ice.

Sensor Module

Reference is made toFIG.6. Inlet42is in fluid communication with analysis chamber44which receives sample gases and puts them into contact with carbon monoxide sensor46, Ethylene sensor45and a temperature, pressure and humidity sensor unit48. The analysis chamber44is shown as passing the sample gases sequentially between these sensors (Temp/pressure/humidity unit, ethylene, CO) but there could be a sinuous chamber, or the sensor units could be arranged in parallel with the others in one common analysis chamber44, say, around the outside of it, so that there is a simultaneous reading of all component gases from the one sample.

The sensors45,46, and48are connected to the main controller25so as to transfer data thereto, either wirelessly or in a wired or other suitable way (such as optically if suitable). The connections are so that the controller25can provide central monitoring of the analysis process for multiple gas concentrations simultaneously, and apply any one of a plurality of correction regimes during and before and after analysis as described below.

Main Controller

The target gas result can be obtained by transmitting data from the ethylene sensor45into the main controller25. The main controller25displays the results on a display (not shown).

To obtain a more accurate result, the gas component reading can be refined by combining the ethylene sensor45and correcting it with offsets or multiplication factors based on the readings from any combination of the other sensor readings in the system. As one example, the ethylene reading could be obtained by taking the ethylene sensor45reading, and providing a correction offset based on the carbon monoxide detected in the sample, in order to calculate a more accurate ethylene reading. This is advantageous as some ethylene sensor readings may also be impacted by carbon monoxide gas, and the present invention could be used to remove such inaccuracies in the ethylene reading.

This is done by for example,

An automatic calibration method is employed, comprising the steps of taking of a number of measurements based on various concentration multiples, wherein the concentration multiple is controlled by the main controller25by varying the mass flow past the concentrator prior to each gas analysis, and a calibration curve of sensor readings vs concentration multiple is obtained. An interception of the calibration curve with the Y axis may then be mathematically determined to calculate a calibration offset, and that calibration offset may be applied to ethylene readings to increase accuracy and reduce sensor drift inherent in typical electrochemical sensors.

In an alternative embodiment and as part of an automated calibration step, a known gas sample, such as from a calibration gas canister or other generated means, may be passed through the gas analysis unit44, and gas sensor readings can be compared with the known gas sample concentrations, and any variations in readings between measured and known values may be offset from future gas sample readings in order to improve accuracy.

Overload Detection

An automatic concentration overload detection method is employed in some embodiments to prevent damage to, or inaccuracy of, the gas analysis sensors45and46. This feature includes the steps of taking a first measurement based on a low (or no) concentration multiple, wherein if it is determined that the gas sample is further concentrated a sensor overload may occur, higher concentration steps may not be completed and an error message generated.

The automatic concentration overload detection method consists of reading the carbon monoxide sensor (or an alternative sensor), and abandoning the measurement if concentrations are higher than a preferred threshold.

The sensor unit40is in fluid connection to the outlet61, where the used gas sample is exhausted back into the atmosphere.

The system can be mounted in a housing and placed inside a chamber in which is disposed ripening produce.

The controller25includes a memory, processor, I/O port for data transfer and therefore can be programmed to implement control of gas measurement steps and calibrations, and monitoring of the desired atmosphere (not shown).

The calibration cycles and regimes can be programmed into the controller25for routine implementation, or when one gas is measured as being off design, or any one of them can be manually actuated by a remote controller such as for example, a mobile device.

The main controller25may connect to a central database server and upload data relating to the gas concentrations, and hence ripeness of fresh produce. The server may then process this data, and provide feedback to users on recommended actions via alerts (such as via SMS messages, push notifications, emails, or recorded phone messages), such that users of the system can reduce produce wastage due to over ripening.

Connection to the database server may be achieved via wired or wireless connection to the internet, or via connection through a third party device (such as via WiFi connection to a smartphone, wherein the smartphone connects to the internet over a 3G/4G/5G connection).

System users may also input into the database, such as via an internet-connected smartphone App (shown onFIG.16), physical observations of fruit ripeness and condition. This data may then be processed in conjunction with previously collected gas sample data, in order to develop optimal algorithms for determining recommended actions. In one embodiment, optimal algorithms may be determined with the use of artificial intelligence and/or machine learning systems.

Example Method

Conditioning

Again, the conditioning step is described here, but as an optional step. Turning toFIG.4, (and the steps inFIGS.14,15and17) there is shown the conditioner15and pump8.

In one particular version of the present method and technology, there is provided a batch processing method. This batch processing method is described below. The continuous processing method is described in relation toFIG.7, where a flow meter17and pump8drive and monitor the sample gas through the system for a selected period of time (say, 30 minutes or 1 hour). It is to be understood that the steps inFIGS.14,15and17apply equally to the continuous processing method, not just the batch processing method.

A sample gas conditioner15draws in a gas and holds it until it meets the right conditions. (Step500inFIG.14,600inFIG.15,700inFIG.17)). First, there is provided a fixed quantity of sample gas. The way the controller becomes aware of the quantity of the gas is that it may be measured by a gas sensor (Step710inFIG.17), or it may be pre-programmed into the controller25, (since it may know the volume in a pump8and its revolutions or cycles utilized) or the quantity of sample gas is controlled by a feedback controlled gas pump, either a piston pump or a peristaltic pump. The main controller25actuates the Peltier device19and the temperature is caused to be dropped to below zero. (Step610inFIG.15, Step720inFIG.17). This freezing step reduces humidity in the sample gas in the chamber4, and periodically then the main controller25actuates the heating element18and opens valve2which removes condensed water.

Concentrating/Separating

The target gas ethylene in the chamber4is transferred by pump8and concentrated via a separation method called carbon adsorption (Step510inFIG.14, Step620inFIG.15, Step730inFIG.17). There may be in one embodiment, several phases.

First, there is a separation/adsorption/store cycle (Step740inFIG.17). In that cycle, 1.5× concentrator volume of cold gas (at sub zero temperature) is pumped through the concentrator30to ensure complete volume exchange. The excess gas is released into the exhaust99.

The main controller25holds a valve81at the inlet9and an outlet valve98in the concentrator closed for a selected time, while it opens the valve2in the conditioner to prepare another sample quantity of gas. The pumping of sample gas and the holding cycles are repeated multiple times, and the excess gas is discarded into the cycle waste exhaust99. The number of separation/adsorption/capture cycles is adjusted until gas readings are obtained within the midrange of the sensor34.

Decant/Release Phase

On the last adsorption cycle, the main controller25actuates the heater elements51to heat the separator store36to a temperature that releases C2H4, but with minimal CO (˜115 deg C.) (Step750inFIG.17).

The concentrator outlet port98is opened to the gas pump108. A pump permits hot gas extraction under a vacuum, which facilitates desorption, and extraction of gas without mixing from the previous chamber.

The main controller25causes the valve98to close.

Cooling Phase

The main controller25may actuate the Peltier units54so that the separator/concentrator is cooled down to a fixed sub-zero temperature in preparation for the next phase of adsorption/capture cycles. This reduces the humidity in the separator/concentrator.

Gas Sensor Conditioning and Pumping

C2H4is stored in the sample chamber and/or conditioner tubing until cooled to a fixed temperature (20 deg C.) in preparation for the gas sensors. When the gas reaches 20 deg (actively controlled), it is expelled across the gas sensors for 3 minutes at atmospheric pressure. The pump8is feedback controlled that ensures the gas passes the sensors at atmospheric pressure for 3 minutes.

Two pumping options are possible; a piston pump permits volume changes as the gas changes temperature and has greater volume control over gas quantities than compared to a peristaltic pump.

Sensor Reading and Cleaning Cycles

Once the sample air is 20 deg, it is directed past the sensor module44for 3 mins to obtain the reading. (Step520inFIG.14, Step630inFIG.15, Step760inFIG.17). A tube exiting the gas sensor conditioner transfers gas into a sensor chamber which ensures the gas will pass through and equilibrate with the sensor's reservoir.

Three minutes of gas exposure is controlled by the gas pump (two options; piston pump preferred). A flap at the exit reduces backflow thereby improving one directional flow.

Following the reading cycle, fresh air is drawn by the gas pump, through the conditioner and into the gas sensor chamber for 10-30 mins to reset the sensor for improved sensor performance and lifetime.

In the reading cycle, the target sensor data is sent from sensor45and sensor46and48to the main controller25. The main controller25records the ethylene count (target gas) as shown inFIG.8. The baseline count recording can be seen at90. During the release phase, the peak can be seen rising from the baseline90to peak95and then dropping back. The main controller25subtracts the baseline ethylene count from the peak to obtain a target gas ethylene reading of the sample. The main controller may also calculate the area under the curve (with the baseline being the base) from the moment the curve begins rising from the baseline90to the peak95to obtain the ethylene reading for the concentrated gas. This reading is accurate because it is essentially in a sweet spot for the target gas sensor.

The ethylene reading calculated may then be converted to account for the concentration of the sample. (Step530inFIG.14, Step640inFIG.15, Step770inFIG.17).

To convert the ethylene reading from the target gas sensor to the environmental concentration, a conversion algorithm is prepared and/or solved in the processor. When the amount of sample gas and its conditions are preset and predetermined, the inventors have, surprisingly, and after much hard work, found that a simple graph (in practical terms, stored as a lookup table in the memory of the controller25) such as that shown inFIG.9can be used as a conversion.FIG.9shows the relationship between the ethylene (target gas) sensor45reading (peak-baseline gap output calculation) and environmental gas concentration values.

GapOutput is on the Y-axis ofFIG.9and it relates to the ethylene sensor45reading of the concentrated target ethylene gas, while satConc on the X-axisFIG.9is the environmental concentration of ethylene which correlates with that sensor reading.FIG.9is basically governed by the equation y=mx+c, where c=92, and m=234. So, doing the conversion using the algorithm, the environmental concentration when the ethylene reading is 0.2 ppm is 138.8. This conversion algorithm takes into account the performance of the concentrator at a range of ethylene concentrations.

Changing any of the quantities in the conditioner or concentrator gives you a different slope, y-axis intercept, etc, and a new conversion algorithm can be generated by the processor by receiving data from sensors measuring those quantities.

The ethylene reading calculated above may also be adjusted to account for humidity or pressure or other readings taken from sensor unit48, or unit16, or CO sensor46, and one of those correction factors is CO and is described below and shown inFIGS.10to14. The inventors have identified that ethylene sensors are sensitive to CO gas, and adjustment can be required. The inventors have also noted that CO sensors are sensitive to ethylene gas. The inventors have noted that the responsiveness or sensitivity of certain ethylene sensors to CO is about 8% and the sensitivity of certain CO sensors to ethylene is 50%.

FIG.10is a graph showing the ethylene concentration in ppm measured over time.FIG.11is a graph showing the ethylene concentration after adjustment on the basis of the presence of carbon monoxide.FIG.12is a graph showing the carbon monoxide concentration in ppm measured over time.FIG.13is a graph showing the carbon monoxide concentration in the sample gas after adjustment on the basis of the presence of ethylene.

To resolve this, the two sensitivities can be quantified by solution to the simultaneous equation set out below. The solution to the equations is simplified using the gas sensitivity identified on each of the sensors and the results reduced to a look-up table accessible by the main controller25either on board or on a cloud server.

Equally, the factors correcting for the concentration of ethylene are reduced to data on a lookup table and accessible to the main controller on board or on a cloud server accessible by a wireless module.

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Maintenance

Several processes are useful for longevity and accuracy. Sensor cleaning (occurs every cycle). For each 3 minute of ethylene readings, the gas sensor is flushed with fresh air for 10-30 mins to restore the humidity and stop sensing chemical reactions.

Removal of water from dehumidification. The conditioner coil will retain ice after a while. This can be removed by heating the coil so the water evaporates or drips out.

Alerts/Alarms

As indicated byFIG.16there may be an assessment step in which the main controller25compares the amount or concentration of the target gas to a threshold level or rate of increase. Then, the main controller25causes the actuation of an alarm sent by SMS or push notification or email by wireless module to a mobile device or computer. The alarm may display on a display or loudspeaker and amplifier on a mobile device or computer.

The alarm step is taken by the processor25if the threshold level or rate of increase is exceeded. This allows the wireless module on the main controller25to alert users of ethylene concentrations and therefore impending ripeness. This allows users to get fruit to market in a decent state.

Clarifications

Modifications and improvements to the invention will be readily apparent to those skilled in the art. Such modifications and improvements are intended to be within the scope of this invention.