In Situ Radio Frequency Heating

Task Description

This technology involves the use of radio frequency (RF) energy to heat vadose zone sediments through a dielectric heating mech-
anism in which the application of an electromagnetic field physically distorts the molecular structure of the material (Figure 5.2). The phy-
sical distortion is transferred into mechanical and then into thermal energy. The frequencies applic-
able for heating earthen materials and mineral formations lie be-
tween 0.01 and 60 MHz. The most commonly used frequencies, 6.78 and 13.56 MHz, are those set aside for use by industrial, scientific, and medical equipment. Because of its ability to penetrate and couple

with the soil, RF heating is faster than convective or conductive heating modes.

The RF heating project is centered around the use of a dipole appli-
cator developed and patented by KAI Technologies, Inc. The single wand applicator, approximately 20 feet in length, is constructed of flexible copper coaxial cable to facilitate the use of a horizontal well drilled to dissect and traverse a shallow clay lens located from 35 to 40 feet below the ground surface.

Computer modeling was perform-
ed to determine the output imped-
ance history and temperature con-
tours. The modeling was based on laboratory measurements of repre-
sentative soils and assumes a