Variable frequency automated capacitive radio frequency (RF) dielectric heating system
AssigneesState of Oregon acting by and through the State Board of Higher Education on behalf of Oregon State University, Benjamin A. Flugstad
InventorsBenjamin A. Flugstad, Qingyue Ling, Edward R. Kolbe, John Henry Wells, Yanyun Zhao, Jae W. Park
Life of this patent
Estimating the term…
Abstract
A food product is heated by maintaining the food product in an AC electrical field generated by an RF signal. As the heating takes place, maximum energy is delivered to the food product using automatic impedance matching to adjust the rate of the process.
Claims28
A capacitive RF dielectric heating apparatus for treating food products, the apparatus comprising:
- a source of an AC RF signal at an RF frequency not greater than 300 MHz, the source being connected to a pair of electrodes on opposite sides of a product treatment zone to cause an RF signal to generate an AC electric field in the product treatment zone;
- a frequency controller to adjust the frequency of the RF signal between different RF frequencies;
- a mathematical model that predicts impedance of the food products as a function of temperature;
- an impedance sensor to sense an impedance of the food products;
- a computer programmed to receive impedance data from the impedance sensor, to process the impedance data using the model for the product, and to apply a control signal to the frequency controller to adjust the frequency of the RF signal to match the sensed impedance to a predetermined impedance.
A capacitive RF dielectric heating apparatus for treating food and seed products, the apparatus comprising:
- a source of an AC RF signal at a frequency not greater than 300 MHz;
- a first electrode that is connected to the source;
- a second electrode that is connected to the source and that is spaced from the first electrode so that a product treatment zone is defined between the electrodes and an RF signal flows through the product treatment zone;
- and
- impedance matching means for matching an impedance of the heated food or seed products to a predetermined constant by adjusting the frequency of the RF signal.
A capacitive dielectric (RF) heating apparatus from treating food products, the apparatus comprising:
- at least one pair of spaced-apart electrodes defining therebetween a food product treatment zone that can accommodate a food product to be treated;
- signal generating circuitry connected to the electrodes, the signal generating circuitry being capable of providing an AC RF signal to charge the electrodes and generate an AC electric field in the food product treatment zone;
- impedance measuring circuitry connected to the electrodes and to the signal generating circuitry, the impedance measuring circuitry measuring an impedance of the electrodes and the food product within the food product treatment zone;
- and
- a controller linked to the impedance measuring circuitry and the signal generating circuitry, the controller controlling the signal generating circuitry and the AC electric field generated thereby based on the impedance measured by the impedance measuring circuitry.
A capacitive RF dielectric heating apparatus for treating food and seed products, the apparatus comprising:
- a source of an AC RF signal at an RF frequency not greater than 300 MHz, the source being connected to a pair of electrodes on opposite sides of a product treatment zone to cause an RF signal to flow through the product treatment zone;
- a frequency controller to adjust the frequency of the RF signal between different RF frequencies;
- a mathematical model that predicts Debye resonance frequency as a function of temperature for a product to be heated by the apparatus;
- a temperature sensor to measure the temperature of a product located in the zone;
- a computer programmed to receive temperature data from the temperature sensor, to process the temperature data using the model for the product, and to apply a control signal to the frequency controller to adjust the frequency of the RF signal to a Debye resonance frequency of the product at the sensed temperature in the zone.
A capacitive RF dielectric heating apparatus for treating food and seed products, the apparatus comprising:
- a source of an AC RF signal at a frequency not greater than 300 MHz;
- a first electrode that is connected to the source;
- a second electrode that is connected to the source and that is spaced from the first electrode so that a product treatment zone is defined between the electrodes and an RF signal flows through the product treatment zone;
- multiple temperature sensors positioned to measure the temperature at multiple regions of a product located in the zone;
- and
- a computer which receives temperature data from the temperature sensors, processes the temperature data using a model for the product, and adjusts at least one characteristic of the RF signal in response to changes in the sensed temperatures in the zone.
A system for heating a medium that includes a food product, comprising:
- means for subjecting the medium to an AC electrical field generated by an RF waveform applied at a selected frequency that heats the medium;
- means for measuring an effective load impedance initially dependent upon the impedance of the medium;
- means for comparing the effective load impedance with an output impedance of a signal generating unit that generates the RF waveform;
- and
- means for automatically adjusting the effective load impedance to match the signal generating unit output impedance.
Dependencies are inferred from the claim text.