ABSTRACT
An Ohmic heating device for electrical conductivity measurement can be a glass, polycarbonate or Teflon cylinder with (possibly) 1 in. internal diameter (Wang and Sastry, 1997a,b; Lima et al., 1999; Castro et al., 2003 and 2004; Zareifard et al., 2003; Kulshrestha and Sastry, 2006). Palaniappan and Sastry (1991a,b), a steel tube with a Teflon sleeve inside it, for electrical insulation and inertness, to make a cylindrical sample chamber. The steel tube device is the first-generation device, and is not currently the recommended option. The ends of the cylinder are fitted with electrodes and secured using plastic spacers. The distance between the electrodes can be varied. The electrode seals are maintained with o-rings. The sample of which electrical conductivity is to be measured is placed between the electrodes, taking care to ensure that the sample is in contact with electrodes at all times. There may be one or more ports on the top for locating thermocouples or pouring liquid
materials. The holes can be equipped with pressurized fittings for type-T thermocouples for monitoring temperatures. These are basically static Ohmic heating cell units; however, the cells can be mounted on a shaker to ensure mixing of the material (Wang and Sastry, 1997a). The heaters can be jacketed for maintaining temperature inside the cell (Palaniappan and Sastry, 1991a,b; Castro et al., 2004). These heaters can also be pressurized and electrical conductivity measurements done at elevated temperatures.
