Dielectric heating in industry application of radio frequency and microwaves

1981 ◽  
Vol 128 (9) ◽  
pp. 583 ◽  
Author(s):  
Pat Hulls ◽  
Ralph Shute
Keyword(s):  
Radio Frequency ◽  
Dielectric Heating

scholarly journals Dielektrické vlastnosti zemědělských produktů a některé jejich aplikace

2008 ◽  
Vol 54 (No. 2) ◽  
pp. 104-112 ◽  
Author(s):  
S.O Nelson
Keyword(s):  
Dielectric Properties ◽  
Moisture Content ◽  
Radio Frequency ◽  
Fruits And Vegetables ◽  
Agricultural Products ◽  
Dielectric Heating ◽  
Quality Factors ◽  
Poultry Products ◽  
Microwave Dielectric ◽  
Microwave Dielectric Heating

The use of dielectric properties of agricultural products for sensing moisture in grain and seed and their application in radio-frequency and microwave dielectric heating is discussed briefly. Values for the dielectric properties of a number of products, including grain and seed, fruits and vegetables, and poultry products, are presented graphically to show the dependence of these properties on frequency, moisture content, and temperature. The potential for using the dielectric properties to sense quality factors other than moisture content is also considered.

scholarly journals Effects of Moisture, Temperature, and Salt Content on the Dielectric Properties of Pecan Kernels During Microwave and Radio Frequency Drying Processes

Foods ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 385 ◽  
Author(s):  
Zhang ◽  
Li ◽  
Cheng ◽  
Wang ◽  
Ding ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Moisture Content ◽  
Radio Frequency ◽  
Salt Content ◽  
Rf Heating ◽  
Dielectric Heating ◽  
Time Histories ◽  
Properties Of Materials ◽  
Content Range ◽  
Temperature Time

Dielectric properties of materials influence the interaction of electromagnetic fields with and are therefore important in designing effective dielectric heating processes. We investigated the dielectric properties (DPs) of pecan kernels between 10 and 3000 MHz using a Novocontrol broadband dielectric spectrometer in a temperature range of 5–65 °C and a moisture content range of 10–30% wet basis (wb) at three salt levels. The dielectric constant (ε′) and loss factor (ε′′) of the pecan kernels decreased significantly with increasing frequency in the radio frequency (RF) band, but gradually in the measured microwave (MW) band. The moisture content and temperature increase greatly contributed to the increase in the ε′ and ε′′ of samples, and ε′′ increased sharply with increasing salt strength. Quadratic polynomial models were established to simulate DPs as functions of temperature and moisture content at four frequencies (27, 40, 915, and 2450 MHz), with R2 > 0.94. The average penetration depth of pecan kernels in the RF band was greater than that in the MW band (238.17 ± 21.78 cm vs. 15.23 ± 7.36 cm; p < 0.01). Based on the measured DP data, the simulated and experimental temperature-time histories of pecan kernels at five moisture contents were compared within the 5 min RF heating period.

Microwave Processing of Polymers and Biomass Materials

1988 ◽  
Vol 124 ◽  
Author(s):  
Clifford E. George ◽  
G. R. Lightsey ◽  
A. G. Wehr
Keyword(s):  
Quality Control ◽  
Radio Frequency ◽  
Wood Flour ◽  
Biomass Conversion ◽  
Microwave Processing ◽  
Conversion Process ◽  
Dielectric Heating ◽  
Polymer Blending ◽  
Biomass Materials ◽  
Drying Quality

ABSTRACTDielectric heating techniques have been applied to plastics drying applications, polymer blending, wood flour drying, and to an existing biomass conversion process. While both radio frequency and microwave equipment is expensive per unit of capacity, certain advantages may be gained in terms of the speed of drying, quality control, and the overall capitalized cost which may make dielectric heating feasible.

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