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Title:
RADIO FREQUENCY SYSTEM AND METHOD FOR MITIGATING INFESTATION IN AGRICULTURAL CROPS
Document Type and Number:
WIPO Patent Application WO/2015/026303
Kind Code:
A1
Abstract:
The present disclosure relates to a radio frequency system for mitigating infestation in agricultural crops, as well as a method of an application of the system. The system comprises a treatment apparatus for treating the agricultural crops with radio frequency radiation. The system also comprises an outlet feeder for feeding the agricultural crops into the treatment apparatus. The agricultural crops flow vertically through the treatment apparatus after being fed therein. An advantage of the present disclosure is that the agricultural crops are continuously flowing through the system, such that the agricultural crops are subject to radio frequency radiation from the treatment apparatus as they vertically flow through the treatment apparatus. Another advantage is that there are lesser spaces within the agricultural crops due to the vertical flow, leading to more efficient use of the radio frequency radiation from the treatment apparatus.

Inventors:
VEARSILP, Suchada (29/68 Tung Hotel Rd, Wat Ket Muang, Chiang Mai, 50000, TH)
THANAPORNPOONPONG, Sa-Nguansak (Faculty of Agriculture, Chiang Mai University,239 Huay Kaew Road, Suthep, Muang, Chiang Mai, 50200, TH)
KRITTIGAMAS, Nattasak (Faculty of Agriculture, Chiang Mai University,239 Huay Kaew Road, Suthep, Muang, Chiang Mai, 50200, TH)
SURIYONG, Sangtiwa (Faculty of Agriculture, Chiang Mai University,239 Huay Kaew Road, Suthep, Muang, Chiang Mai, 50200, TH)
Application Number:
TH2014/000030
Publication Date:
February 26, 2015
Filing Date:
June 30, 2014
Export Citation:
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Assignee:
AGRICULTURAL RESEARCH DEVELOPMENT AGENCY (PUBLIC ORGANIZATION) (2003/61 Phaholyothin Rd, Ladyao Chatuchak, Bangkok, 10900, TH)
NATIONAL RESEARCH COUNCIL OF THAILAND (196 Phaholyothin Rd, Ladyao Chatuchak, Bangkok, 10900, TH)
CHIANG MAI UNIVERSITY (239 Huay Kaew Road, Muang District, Chiang Mai, 50200, TH)
International Classes:
A01M17/00; A01M1/00; A23B9/00
Foreign References:
CA975434A
JP2012187037A
JPH08308911A
Attorney, Agent or Firm:
PHANGSEE, Budsarakam et al. (Axis Associates International Co. Ltd, 253 Asoke, 15th Floor, Sukhumvit 21 Road,Klongtoey Nua, Wattana, Bangkok, 10110, TH)
Download PDF:
Claims:
Claims

1. A radio frequency system for mitigating infestation in agricultural crops, the system comprising:

a treatment apparatus for treating the agricultural crops with radio frequency radiation; and

an outlet feeder for feeding the agricultural crops into the treatment apparatus,

wherein the agricultural crops flow vertically through the treatment apparatus after being fed therein. 2. The system as in claim 1 , the treatment apparatus comprising an irradiating unit for irradiating the agricultural crops with radio frequency radiation.

3. The system as in claim 2, the treatment apparatus further comprising a preheating unit connected to the irradiating unit, the preheating unit for heating the agricultural crops before the agricultural crops are irradiated. 4. The system as in claim 2 or 3, the treatment apparatus further comprising a cooling unit connected to the irradiating unit, the cooling unit for cooling the agricultural crops after the agricultural crops are irradiated.

5. The system as in claim 4, wherein the agricultural crops flow through the preheating unit, the irradiating unit, and the cooling unit sequentially. 6. The system as in claim 4, the cooling unit further for maintaining the agricultural crops at a predetermined temperature for a predetermined duration of time.

7. The system as in claim 4, the treatment apparatus further comprising a heat exchanger for exchanging heat between the preheating unit and the cooling unit.

8. The system as in claim 2, the irradiating unit further comprising a set of electrodes for generating an electric field.

9. The system as in claim 1, further comprising a set of controls for controlling a flow rate of the agricultural crops from the outlet feeder.

10. The system as in claim 9, wherein the set of controls is for at least one of monitoring and controlling parameters from the treatment apparatus.

1 1. A radio frequency method for mitigating infestation in agricultural crops, the method comprising:

feeding the agricultural crops from an outlet feeder into a treatment apparatus;

treating the agricultural crops with radio frequency radiation from the treatment apparatus;

wherein the agricultural crops flow vertically through the treatment apparatus after being fed therein.

12. The method as in claim 11, further comprising irradiating the agricultural crops with radio frequency radiation from an irradiating unit of the treatment apparatus.

13. The method as in claim 12, further comprising heating the agricultural crops with a preheating unit of the treatment apparatus, before the agricultural crops are irradiated, wherein the preheating unit is connected to the irradiating unit.

14. The method as in claim 12 or 13, further comprising cooling the agricultural crops with a cooling unit of the treatment apparatus, after the agricultural crops are irradiated, wherein the cooling unit is connected to the irradiating unit.

15. The method as in claim 14, wherein the agricultural crops flow through the preheating unit, the irradiating unit, and the cooling unit sequentially.

16. The method as in claim 14, further comprising maintaining the agricultural crops at a predetermined temperature for a predetermined duration of time with the cooling unit.

17. The method as in claim 14, further comprising exchanging heat between the preheating unit and the cooling unit with a heat exchanger of the treatment apparatus.

18. The method as in claim 12, further comprising generating an electric field with a set of electrodes from the irradiating unit.

19. The method as in claim 1 1, further comprising for controlling a flow rate of the agricultural crops from the outlet feeder with a set of controls.

20. The method as in claim 19, further comprising at least one of monitoring and controllmg parameters from the treatment apparatus with the set of controls.

Description:
RADIO FREQUENCY SYSTEM AND METHOD FOR MITIGATING

INFESTATION IN AGRICULTURAL CROPS

Technical Fiejd

The present disclosure generally relates to a radio frequency system and method for mitigating infestation in agricultural crops, crop materials, and/or crop products. More particularly, the present disclosure describes various embodiments of a radio frequency system for controlling and/or mitigating infestation in agricultural crops, crop materials, and/or crop products as well as a method of an application of the radio frequency system.

Background Different systems and methods have been used for controlling and/or mitigating infestation of agricultural crops, by controlling, killing, and/or eliminating parasites, pests, and insects in the agricultural crops. These parasites, pests, and insects may include rice weevils, rice moths, corn weevils, and beetles. The agricultural crops may include seeds and grains of wheat, corn, rice, and millet. One method is to use a basic heat generator or source to heat the agricultural crops. The outer surfaces of the agricultural crops are first heated before the heat energy is subsequently conducted deeper into the agricultural crops. The heat energy may not be sufficient or strong enough to penetrate into the core of the agricultural crops. In such situations, pests and insects that are deeper in the agricultural crops may not be affected, unless a stronger heat source is used. If such a stronger heat source is used to increase the heat energy in order to penetrate deeper, the outer surfaces of the agricultural crops could be damaged by the high temperatures. Such external-to-internal heating could even damage the outer surfaces before the heat even reaches the inner cores of the agricultural crops. Another method is to use electromagnetic waves or radiation to irradiate onto the agricultural crops. The electromagnetic radiation is generally within the range of radio frequencies, also known as radio frequency waves or radiation. For scientific and industrial purposes, only the frequencies of 13.56, 27.12, and 40.68 megahertz (MHz) may be used for the radio frequency radiation. Lower frequency radiation has a higher penetration rate, such that they can penetrate deeper into the agricultural crops, which is suitable for larger-sized seeds and grains. The irradiation of the agricultural crops with radio frequency radiation is also known as radio frequency heating or dielectric heating. Such heating process is more efficiency in heat distribution and is more rapid, resulting in less energy consumption.

The radio frequency radiation is caused by applying an alternating electric field between capacitor plates or electrodes. A material placed between within the electric field will be irradiated by the radio frequency radiation, thereby heating the material. The material contains polar molecules having an electrical dipole moment. The electric field causes the polar molecules in the material to continuously reorient them in different directions. Molecular friction resulting from the molecular movement causes the material to rapidly heat up throughout its entire mass. The agitated or excited molecules also move faster within the material, thereby increasing the average kinetic energy of the molecules and thus the temperature of the material. Therefore, because of the rapid oscillation of the molecules within the material, heat is more uniformly generated from within the material and conducted to the external surfaces, otherwise known as internal-to-external heating.

Research has been done on using electromagnetic radiation to address the problem of parasites, pest, and insect infestation in agricultural crops, which has severely affected the quality of agricultural products. For example, Weerayout Faikrajaypuan et al. (Effect of Heat from Radio Frequency on Maize Weevil, 2011) had researched that using radio frequency radiation at 780 watts for 3 minutes can effectively kill maize or corn weevils. Additionally, Stuart O. Nelson (RF and Microwave Energy for Potential Agricultural Applications, 1985) had experimented on killing rice weevils using radio frequency waves and microwaves, and the death rate in both groups were the same. However, unlike radio frequency waves, microwaves induce a higher temperature to the agricultural crops, thereby causing greater damage. The use of radio frequency radiation has been applied in the development of methods, systems, and devices for addressing the at least one of the aforementioned infestation problems in agricultural crops.

United States patent number 6,346,693 discloses a heating system for removing moisture in grains. The system comprises a containment vessel and an electromagnetic energy source. The heat from the electromagnetic energy source within the containment vessel flows through the grains in order to conduct the heat through to the outside of the containment vessel. This system is operated in the heated containment vessel and there is no flow of the grains. Due to the grains being stationary in the vessel for irradiation by electromagnetic radiation, a large vessel is necessary in order to maintain efficiency of the process. However, a large vessel would lead to greater energy usage because the electromagnetic radiation needs to penetrate deeper through the grains in the vessel.

Europe patent number 2,399,464 discloses a method for preventive protection of agricultural products, particularly cereals, against attack by pests and pathogens. The method includes applying electromagnetic radiation on the agricultural products. The electromagnetic radiation is in an effective range of from 5 megahertz (MHz) to 250 gigahertz (GHz), preferably from 13 MHz to 45 MHz. The agricultural products are continuously moving by means of a horizontal conveyor belt, and are irradiated by the electromagnetic radiation during the motion on the conveyor belt. One problem associated with this method is that a large floor area is required to set up the system, due to the use of the conveyor belt. Space constraints may reduce the scale of using such a method and thereby reduce the quantity of agricultural products that have been treated with the electromagnetic radiation.

Therefore, in order to address at least one of the aforementioned problems and/or disadvantages, there is a need to provide a system and method for mitigating infestations in agricultural crops using radio frequency, in which there are improved features compared to the aforementioned prior art.

Summary

According to a first aspect of the present disclosure, there is a radio frequency system for mitigating infestation in agricultural crops. The system comprises a treatment apparatus for treating the agricultural crops with radio frequency radiation. The system also comprises an outlet feeder for feeding the agricultural crops into the treatment apparatus. The agricultural crops flow vertically through the treatment apparatus after being fed therein.

According to a second aspect of the present disclosure, there is a radio frequency method for mitigating infestation in agricultural crops. The method comprises feeding the agricultural crops from an outlet feeder into a treatment apparatus. The method also comprises treating the agricultural crops with radio frequency radiation from the treatment apparatus. The agricultural crops flow vertically through the treatment apparatus after being fed therein. An advantage of the present disclosure is that the agricultural crops are continuously flowing through the system, such that the agricultural crops are subject to radio frequency radiation from the treatment apparatus as they vertically flow through the treatment apparatus. There is thus a reduced need for a large containment vessel for the agricultural crops because of the continuous flow and the treatment during the flow. By having the flow being in a substantially vertical direction, equipment for the system can be installed vertically upwards, thereby reducing the floor area required to implement such a system. The vertical flow of the agricultural crops keeps the density of various portions of the agricultural crops consistent, because gravity assists in compressing the spaces between the portions. Advantageously, there are lesser spaces within the agricultural crops, due to the vertical flow, leading to more efficient use of the radio frequency radiation from the treatment apparatus.

Preferably, the treatment apparatus comprises an irradiating unit for irradiating the agricultural crops with radio frequency radiation. The treatment apparatus further comprises a preheating unit connected to the irradiating unit, the preheating unit for heating the agricultural crops before the agricultural crops are irradiated. The treatment apparatus yet further comprises a cooling unit connected to the irradiating unit, the cooling unit for cooling the agricultural crops after the agricultural crops are irradiated. The cooling can maintain the agricultural crops at a predetermined temperature for a predetermined duration of time. An advantage of the preheating unit is to reduce the temperature differential when the agricultural crops reach the irradiating unit, thereby reducing the energy consumption of the irradiating unit and improving energy efficiency. An advantage of the cooling unit is to reduce the temperature of the heated and irradiated agricultural crops sufficiently in order to be processed in the subsequent stages. In this arrangement, the agricultural crops flow through the preheating unit, the irradiating unit, and the cooling unit sequentially. Preferably, treatment apparatus comprises a heat exchanger for exchanging heat between the preheating unit and the cooling unit. This advantageously allows the preheating unit to make use of heat that is absorbed by the cooling unit when the agricultural crops are cooled therein. The irradiating unit preferably comprises a set of electrodes for generating an electric field, such that the agricultural crops can be sandwiched in between the electrodes in order to be irradiated.

Further, the system preferably comprises a set of controls for controlling a flow rate of the agricultural crops from the outlet feeder, as well as monitoring and/or controlling parameters from the treatment apparatus. An advantage of this feature is that it allows users of the system to adjust the system according to requirements and specifications, especially when dealing with different types and sizes of agricultural crops which have different electromagnetic or dielectric properties.

A radio frequency system and method according to the present disclosure is thus disclosed hereinabove. Various features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description of the embodiments of the present disclosure, by way of non-limiting examples only, along with the accompanying drawings in which like numerals represent like components.

Brief Description of the Drawings FIG. 1 is a schematic diagram of a radio frequency system according to an embodiment of the present disclosure.

FIG. 2 is a schematic diagram of a treatment apparatus of the radio frequency system according to an embodiment of the present disclosure.

FIG. 3 is a flowchart of a method of an application of the radio frequency system according to an embodiment of the present disclosure. Detailed Description

Various embodiments of the present disclosure are directed toward structural and functional aspects of a radio frequency system and method for mitigating infestation in agricultural crops. In the context of the present disclosure, the term "agricultural crops" is defined to encompass one or more types of agricultural crops, crop materials, or crop products. While aspects of the present disclosure will be described in conjunction with the embodiments provided herein, it will be understood that they are not intended to limit the present disclosure to these embodiments. On the contrary, the present disclosure is intended to cover alternatives, modifications and equivalents, which can be included within the spirit and scope of the present disclosure as defined by the appended claims. Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be recognized by one of ordinary skill in the art that the present disclosure can be practiced without at least some of these specific details. In other instances, well-known systems, methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the embodiments of the present disclosure.

Unless explicitly stated otherwise, in the description herein the recitation of particular numerical values or value ranges is taken to be a recitation of particular approximate numerical values or approximate value ranges. For purposes of brevity and clarity, descriptions of embodiments of the present disclosure are limited hereinafter to a radio frequency system and method for mitigating infestation in agricultural crops, in accordance with the drawings in FIG. 1 to FIG. 3. This, however, does not preclude embodiments of the present disclosure where fundamental principles prevalent among the various embodiments of the present disclosure such as operational, functional or performance characteristics are required.

In a representative or preferred embodiment of the present disclosure, a radio frequency system 10 for controlling and/or mitigating infestation in agricultural crops, including a method of an application of the system 10, is described hereinafter.

The radio frequency system 10 and method thereof controls and/or mitigates infestation of the agricultural crops by controlling, killing, reducing, and/or eliminating parasites, pests, and insects in the agricultural crops. FIG. 1 shows a schematic illustration of a radio frequency system 10 for mitigating infestation in agricultural crops according to the preferred embodiment of the present disclosure. In the preferred embodiment, the system 10 comprises a treatment apparatus 12 and an outlet feeder 14. The treatment apparatus 12 is for treating the agricultural crops with radio frequency radiation and the outlet feeder 14 is for feeding or discharging the agricultural crops into the treatment apparatus 12. The agricultural crops are stored in a storage unit 16 of the system 10 prior to being discharged or fed from the outlet feeder 14. The treatment apparatus 12 is positioned in a substantially vertical manner as shown in FIG. 1, such that the agricultural crops are fed to the top portion of the treatment apparatus 12, thereby allowing the agricultural crops to flow vertically downwards through the treatment apparatus 12.

The storage unit 16 is useful for industries that require bulk storage of their agricultural crops or raw materials. The storage unit 16 is positioned adjacent and proximate to the treatment apparatus 12. A transport mechanism, pipe, or line 18 connects the storage unit 16 to the outlet feeder 14, wherein the agricultural crops is discharged or transported (e.g., vertically, or at a given angle relative to vertical) through the transport pipe 18. In a representative. or preferred embodiment, the outlet feeder 14 is positioned vertically above the treatment apparatus 12 and the storage unit 16. This requires the installation of a pumping or discharging device (not shown) to transport the agricultural crops vertically upwards along the transport pipe 18 towards the outlet feeder. Alternatively, the storage unit 16 can be positioned above the outlet feeder 14, such that the agricultural crops stored in the storage unit 16 can flow downwards under the force of gravity into the outlet feeder 14 and subsequently into the treatment apparatus 12. The pumping device can also include structures, features, and/or functions to control the flow rate of the agricultural crops from the storage unit 16 to the outlet feeder 14 through the transport pipe 18. Additionally, the outlet feeder 14 can also include structure, functions, and/or features to automatically control the flow rate of the output and the time duration of the flow. For example, the outlet feeder 14 and/or the pumping device can control the amount of agricultural crops that are discharged into the treatment apparatus 12 within a predetermined duration of time. The outlet feeder 14 and/or the pumping device can also control the timing of the flow, such as setting a cut-off time to automatically terminate the flow after a predetermined duration of time or after a predetermined amount of agricultural crops have flowed through.

As shown in FIG. 1 , in some embodiments the system 10 also comprises a conveyor or screw feeder 20 for transporting the treated agricultural crops to a packaging system 22. The conveyor 20 is connected to a bottom portion of the treatment apparatus 12 in order to receive the agricultural crops that have been treated with the radio frequency radiation when they flow downwardly through the treatment apparatus 12. The conveyor or screw feeder 20 is controlled by a motorized component (not shown) that rotates the conveyor 20 and allows the treated agricultural crops to move outwards towards the packaging system 22, where the agricultural crops will be further processed into various agricultural products. The rate of rotation can be controlled in order to vary the transport rate of the treated agricultural crops to the packaging system 22. Moreover, instead of a screw feeder, a horizontal conveyor belt can be used to transport the treated agricultural crops to the packaging system 22. Alternatively or additionally, other forms of transportation or conveying means known to a person having ordinary skill in the art can be used.

The agricultural crops are treated with radio frequency radiation as they flow vertically through the treatment apparatus 12. FIG. 1 shows the treatment apparatus 12 comprising a preheating unit 24, an irradiating unit 26, and a cooling unit 28. In the preferred embodiment as shown in FIG. 2, the treatment apparatus 12 is positioned in a vertical manner to allow downward flow of the agricultural crops by gravity or gravitational force. The preheating unit 24 is positioned at the top portion of the treatment apparatus 12; the irradiating unit 26 is positioned at the middle portion of the treatment apparatus 12; and the cooling unit 28 is positioned at the bottom portion of the treatment apparatus 12. The bottom portion of the preheating unit 24 is connected or coupled to the top portion of the irradiating unit 26, and the bottom portion of the irradiating unit 26 is connected or coupled to the top portion of the cooling unit 28. Thus, in a frontal view of the system 10 as shown in FIG. 1 and FIG. 2, the treatment apparatus 12 has a vertical arrangement with the respective units - preheating unit 24, irradiating unit 26, and cooling unit 28 - arranged in a top-down sequence. As the agricultural crops flow out from the outlet feeder 14 into the treatment apparatus 12, they flow vertically downwards through the preheating unit 24, irradiating unit 26, and cooling unit 28, sequentially. The various units (24, 26, and 28) are connected or coupled close to one another in order to minimize the vertical height of the treatment apparatus 12 and to improve efficiency of the system 10. The means of connection or coupling between the various units (24, 26, and 28) will be apparent to and understood by the person having ordinary skill in the art. FIG. 3 shows a flowchart of the different stages of a treatment process 500 of the agricultural crops flowing through the treatment apparatus 12, according to the preferred embodiment of the present disclosure. In the first stage 100 of the treatment process 500 through the treatment apparatus 12, the agricultural crops are conventionally heated by the preheating unit 24. The preheating unit 24 comprises a conventional heat generator to transmit heat energy to the agricultural crops, thereby heating them, in an external-to- internal manner as described above. At the first stage 100, the average temperature of the agricultural crops is raised from the environmental temperature to a predetermined temperature, preferably 40 °C. The system 10 comprises a set of controls (not shown) for controlling the intensity of heat from the preheating unit 24. For example, if a larger amount of agricultural crops is flowing through the preheating unit 24, the intensity of heat from the preheating unit 24 needs to be higher. This is necessary in order to raise the average temperature of a substantial portion of the agricultural crops to the preferred 40 °C during the time period when the agricultural crops are passing through the preheating unit 24. Additionally, the predetermined temperature to be effected by the preheating unit 24 can be adjusted depending on the requirements and specifications.

Referring to FIG. 3, in the second stage 200 of the treatment process 500 through the treatment apparatus 12, the agricultural crops are irradiated with radio frequency radiation from the irradiating unit 26. Referring to FIG. 2, the irradiating unit 26 comprises a radio frequency generator 30 and a pair of electrodes 32. The radio frequency generator 30 creates an alternating electric field between the electrodes 32. When the agricultural crops flow in between the electrodes 32, the alternating electric field agitates and excites the molecules in the agricultural crops. The agitated or excited molecules also move faster, thereby increasing the temperature of the agricultural crops. Therefore, because of the rapid movement of the molecules, heat is more uniformly generated in an internal-to- external heating. In the preferred embodiment, the frequency of the radio frequency radiation is 27.12 MHz. However, the frequency can also be either 13.56 MHz or 40.68 MHz, in order to conform to scientific and industrial requirements. The intensity of the electric field generated by the radio frequency generator 30 is preferably at least 3.0 kilovolts per metre (kV/m). Each of the electrodes 32 is preferably a flat capacitor plate capable of efficiently generating the electric field and radio frequency radiation using input from the radio frequency generator 30, for irradiating the materials between the electrodes 32. The agricultural crops are the materials to be irradiated, which is also known as the dielectric material. The viscosity, water content, and chemical composition of the agricultural crops affect the dielectric properties and thus the efficiency and effectiveness of the irradiating unit 26.

At the second stage 200 when the agricultural crops are in between the electrodes 32, the electric field and the radio frequency radiation rapidly heats up the agricultural crops to a predetermined temperature, preferably 55 °C. The heat generated by the radio frequency radiation is substantially uniform because of the internal-to-external manner of heating. The irradiated agricultural crops are subsequently maintained at this temperature for 3 minutes, before they leave the irradiating unit 26 to the cooling unit 28. Prior research has shown that the temperature of 55 °C is sufficient to kill a substantial proportion of the parasites, insects, and pests that have contaminated and infested the agricultural crops, such as rice weevils infested in rice crops. The aforementioned set of controls of the system 10 can also be utilized to modify the aforementioned parameters of the irradiating unit 26, including the predetermined temperature to be effected by the irradiating unit 26 and the time duration of maintaining the irradiated agricultural crops at the predetermined temperature. For example, if a larger amount of agricultural crops is flowing through the irradiating unit 26, the intensity of the electric field and the radio frequency radiation from the irradiating unit 26 may need to be higher. This is necessary in order to raise the average temperature of a substantial portion of the agricultural crops to the preferred 55 °C during the time period when the agricultural crops are passing through the irradiating unit 26. An advantage of modifying the parameters is being able to adjust them based on different requirements and specifications, , including the unique natures of different types of agricultural crops which will affect their dielectric properties. As shown in FIG. 2, the irradiating unit 26 further comprises a matching unit 34. The matching unit 34 is used to ensure the combined impedance of the irradiating unit 26, which includes the impedances of the agricultural crops and the electrodes 32. Because different types and sizes of the agricultural crops can vary their impedances, the matching unit 34 functions to maintain consistent overall impedance.

Prior to the agricultural crops reaching the irradiating unit 26 at the second stage 200, they have been heated during the first stage 100 at the preheating unit 24. By performing an initial heating of the agricultural crops, i.e. to 40 °C, there is less energy required by the irradiating unit 26 to further heat up the agricultural crops to 55 °C. This improves energy efficiency of the system 10 and provides greater flexibility in implementing the system 10. For example, the agricultural crops can be first heated by the preheating unit 24 to 50 °C and subsequently by the irradiating unit 26 to 60 °C. More energy would be used by the preheating unit 24 than before, but less would be used by the irradiating unit 26 than before. It should be noted that a higher temperature caused by the preheating unit 24 could potentially damage the outer surfaces of the agricultural crops and thus affect their quality. The overall energy usage of the treatment apparatus 12 may also vary as a whole. Thus, depending on requirements, the predetermined temperatures at both the preheating unit 24 and the irradiating unit 26 can be adjusted in order to optimize the efficiency and effectiveness of the system 10. Such adjustment would be apparent to and understood by the person having ordinary skill in the art based on the preferred embodiment, as well as various aspects of the present disclosure.

Referring to FIG. 2 and FIG. 3, in the third stage 300 of the treatment process 500 through the treatment apparatus 12, the heated and irradiated agricultural crops are cooled in the cooling unit 28. The cooling unit 28 holds the agricultural crops for cooling to a predetermined temperature, and maintains them at the predetermined temperature for a predetermined duration of time. For example, the agricultural crops are cooled to environmental temperature or 30 °C and maintained at that temperature for 5 minutes. The cooling can be performed by air convection currents and/or other means known to the skilled person. The predetermined temperature and the predetermined duration of time are adjustable using the aforementioned set of controls for the system 10 in order to suit different requirements and specifications. For example, if a larger amount of agricultural crops is flowing through the cooling unit 28, the cooling power needs to be higher. This is necessary in order to reduce the average temperature of a substantial portion of the agricultural crops to the preferred 30 °C during the time period when the agricultural crops are at the cooling unit 28. After the predetermined duration of time has passed, the cooled agricultural crops leave the cooling unit 28 towards the conveyor 20 for further processing. An advantage of the cooling unit 28 is to cool the heated and irradiated agricultural crops enough to be processed in the subsequent stages of the radio frequency system 10, such as the packaging system 22.

FIG. 1 and FIG. 2 show a heat exchanger 36 connecting the preheating unit 24 to the cooling unit 28. FIG. 3 shows a stage 400 comprising a heat exchange process performed by the heat exchanger 36 between the preheating unit 24 and the cooling unit 28. The preheating unit 24 functions to preheat the agricultural crops at the first stage 100 of the treatment process 500, and the cooling unit 28 functions to cool the agricultural crops at the third stage 300 of the treatment process 500. Thus, the installation of the heat exchanger 36 improves the efficiency of heat exchange in the preheating unit 24 and the cooling unit 28. Particularly, the cooling unit 28 receives heat from the agricultural crops that are being cooled during the third stage 300. This heat that is received by the cooling unit 28 will be transferred via the heat pipes within the heat exchanger 36 to the preheating unit 24. The preheating unit 24 can utilize the received heat from the cooling unit 28 for heating up the agricultural crops during the first stage 100. Therefore, the preheating unit 24 is able to make use of the heat energy that is absorbed by the cooling unit 28 as a result of the cooling of the agricultural crops during the third stage 300. The heat energy is transmitted by air from the cooling unit 28 to the heat exchanger 36, and from the heat exchanger 36 to the preheating unit 24. Other means of heat exchanger or heat transfer between the various components known to the skilled person can also be used. This cyclic process of heat exchange during the stage 400 improves the efficiency of heat transfer by allowing the preheating unit 24 to recover the heat energy returned from the cooling unit 28. The heat exchanger 36 can also be used by the preheating unit 24 to replace or complement the conventional heat generator in the preheating unit 24. The schematics in FIG. 1 and FIG. 2 show that the radio frequency system 10 is operated in a vertical manner, allowing the agricultural crops to flow substantially vertically downwards, by gravity, through the treatment apparatus 12. There is greater compression of the agricultural crops because the particles or grains are closer together as they are gravitationally pulled downwards. With a smaller gap between the particles or grains, the efficiency of heat transfer during the stages (100, 200, and 300) of the treatment process 500 is improved. This is unlike the conveyor belt system in EP 2,399,464, wherein the agricultural crops are likely to be placed in batches or at intervals along the belt, such that there are empty spaces between successive crop materials or products, or batches of crops, crop materials, or crop products. This makes the system more inefficient because there are instances or positions along the belt when there is irradiation of radio frequency radiation but without any agricultural crops on the belt. In the preferred embodiment of the present disclosure, such disadvantage is mitigated because the crop materials, crop products, or crops are continuously flowing and receiving treatment without or essentially without any intervals or gaps in between. The vertical continuous flow of the agricultural crops reduces the spaces and gaps between the grains and particles of the crops. As such, there is more compression of the agricultural crops to reduce their overall porosity and there is also greater consistency in the densities of different portions of the agricultural crops while they flow through. Therefore, with less spaces and gaps in the agricultural crops and a more consistent density, there is an improvement in their heat conductivity as they pass through the treatment apparatus 12, thereby also improving the efficiency of use of the radio frequency radiation from the treatment apparatus 12.

Aspects of the present disclosure show that the agricultural crops are flowing substantially vertically downwards through the treatment apparatus 12. In the preferred embodiment, the internal channel of the treatment apparatus wherein the agricultural crops flow through is a vertical pipe or tube. Depending on the height of each respective section - the preheating unit 24, the irradiating unit 26, and the cooling unit 28 - of the treatment apparatus 12, the duration of time the agricultural crops spend in each section can vary. For example, if the irradiating unit 26 has a greater height or vertical length, the time taken for the agricultural crops to fall from the top to the bottom of the irradiating unit 26 is higher, thus allowing more time for the agricultural crops to be irradiated with radio frequency radiation from the irradiating unit 26. Additionally, if the height or vertical length of each section is fixed, the treatment apparatus 12 can implement mechanisms or means to restrict or slow down the vertical flow of the agricultural crops. For example, the internal channel of the treatment apparatus 12 can include or be a spiral or zigzag configuration instead of a straight vertical pipe. This would maintain the vertical length of the treatment apparatus 12 while extending the time taken for the agricultural crops to flow from the top to the bottom of the treatment apparatus 12, due to the larger distance based on the length of the spiral or zigzag channel. By extending the time taken, the agricultural crops can be subjected to longer periods of treatment by the respective sections. This is advantageous when there are requirements for such situations, such as when there is a larger amount of agricultural crops with larger grain or particle sizes.

Another advantage of the vertical arrangement of the treatment apparatus 12 in the radio frequency system 10 is that the various components and sections can be built vertically upwards. This is unlike the teachngs of EP 2,399,464, which relies upon a conveyor belt and requires more horizontal space area. The present disclosure implements a vertical system that requires a relatively or significantly smaller area to install and operate, and is thus significantly more space efficient and more convenient to implement and operate compared to other existing systems. Facilities or factories and industries with space constraints will benefit from the use of the system 10.

Due to the use of radio frequency radiation in the system 10, the various components of the system 10, including the treatment apparatus 12, are made from materials that have a high resistance to radio frequency radiation. In particular, the irradiating unit 26 of the treatment apparatus 12 requires materials with higher resistance to radio frequency signals because of the high(er) power or voltages involved and also in order to maintain continuous internal-to-external heating of the agricultural crops. An example of a suitable material is Teflon®. Additionally or alternatively, the components of the system 10 can be surrounded or coated with a layer of electromagnetic frequency shielding.

In order for the agricultural crops to be irradiated with radio frequency radiation from the irradiating unit 26, they need to be located in between the pair of electrodes 32 when they flow or pass through the irradiating unit 26. The agricultural crops can be construed as the material to be irradiated or the absorber; and the electrodes 32 can be construed as the electromagnetic radiator or emitter. The distance between each of the electrodes 32 and the material(s) to be irradiated, i.e. the distance from electromagnetic radiator to absorber, is preferably about 1/2π of the wavelength of the radio frequency waves. At a representative or preferred frequency of 27.12 MHz, the wavelength is approximately 11 metres, resulting in a radiator-to-absorber distance of 1.75 metres. Thus, by allowing the agricultural crops to flow substantially midway between the electrodes 32, the distance between the electrodes 32 is approximately 3.5 metres. In contrast, the embodiment in EP 2,399,464 shows the agricultural crops (absorbers) distributed on a conveyor belt with the radiator directly above. Given the same radio frequency, the radiator-to-absorber distance will be 3.5 metres. Therefore, there is a shorter radiator-to-absorber distance in the present disclosure, resulting in less energy consumption by the irradiating unit 26 and thus improves energy efficiency.

Moreover, the distance between the pair of electrodes 32 can be varied, depending on the type and size of the agricultural crops, and the frequency of the radio frequency radiation, etc., in a manner understood by one having ordinary skill in the relevant art. This allows more flexible usage of the irradiating unit 26 and greater optimization of the treatment apparatus 12, depending on requirements and specifications under consideration. The set of controls for the radio frequency system 10 can be used or operated to control one or multiple parameters of the system 10, such as the flow rate of the agricultural crops, and the intensity / intensities of the treatment apparatus 12. Additionally, the preheating unit 24 and the irradiating unit 26 are equipped with devices or accessories for automatic operating control, such as real-time temperature measurement by fibre optic sensors. Such fibre optic sensors are able to endure the high voltages and electric field, especially in the irradiating unit 26. Further, such accessories can also comprise a proportional-integral- derivative (PID) controller, controls for computer displays, and/or recording devices or functionalities to monitor data derived during or associated with the usage of the system 10. Although the preferred embodiment specifies the agricultural crops to continuously move or flow through the treatment apparatus 12, in an alternative embodiment the agricultural crops can pass through the treatment apparatus 12 in stages or intervals. For example, the agricultural crops can first enter the preheating unit 24 for heating over a predetermined duration of time. During the heating process, i.e. the first stage 100, the agricultural crops are kept stationary at the preheating unit 24 and allow the heating to take place. After a predetermined interval or duration of time has passed, the agricultural crops are released to the second stage 200 for treatment by the irradiating unit 26. Similarly, the agricultural crops are kept stationary at the irradiating unit 24 and allow the irradiation to take place. After another predetermined interval or duration of time has passed, the agricultural crops are released to the third stage 300 for treatment by the cooling unit 28. An advantage of this alternative embodiment is that each stage of the treatment process 500 can be ascertained to have sufficiently treated a substantial portion of the agricultural crops before they move on to the subsequent stage(s). Additionally, the aforementioned spiral or zigzag channels are also applicable to the alternative embodiment.

In another alternative embodiment, the agricultural crops can be discharged, for example, using a pumping device, vertically upwards through the treatment apparatus 12. The preheating unit 24 is located at the bottom of the treatment apparatus 12 and the cooling unit 28 is located at the top of the treatment apparatus 12. The upward flow of the agricultural crops is controlled by the pumping device, such that the pumping device can discharge the agricultural crops through the treatment apparatus 12 at a rate that keeps the agricultural crops substantially compressed. The agricultural crops may be discharged through a pipe or tube of the treatment apparatus 12. If the rate of discharge is sufficiently high, the agricultural crops will be constrained and compressed by the sides of the pipe or tube. Alternatively, the pipe or tube may be tapered or constricted, such that the agricultural crops have to pass through a narrower opening, and thereby becoming compressed in the process. The compression of the agricultural crops creates a more uniform and consistent density, The spaces between each grain or particle of the agricultural crops are more tightly compressed and thus reduced, leading to more efficient use of the radio frequency radiation from the treatment apparatus 12. The treated agricultural crops are subsequently allowed to flow out of the cooling unit 28, after which they can flow vertically downwards for further processing. It would be apparent to and understood by a person having ordinary skill in the art that a method of an application of the radio frequency system 10 is derivable based on the details of the embodiments of the present disclosure.

In the foregoing detailed description, embodiments of the present disclosure in relation to a radio frequency system and method for mitigating infestation in agricultural crops are described with reference to the figures. Although only some embodiments of the present invention are disclosed herein, it will be apparent to a person having ordinary skill in the art in view of this disclosure that numerous changes and/or modifications can be made to the disclosed embodiments without departing from the scope of the present invention. The scope of the disclosure as well as the scope of the following claims is not limited to embodiments described herein.