This paper describes the basic principles and physical modelling of sy
stems based on the ohmic heating of liquids by passage of mains freque
ncy electric current through the liquid itself, in order to heat it on
a continuous flow regime. Preliminary numerical results for non-Newto
nian fluids of Herschel-Bulckley type (Carbopol 940) are presented and
the effect of natural convection, and shear and temperature dependenc
e are emphasized.