Devices for ohmically heating a fluid

A liquid heater comprising:

• (a) a chamber configured to receive a liquid passing therethrough along a flow direction between an inlet and an outlet;
• (b) a plurality of rod-like electrodes disposed within the chamber and extending substantially parallel to one another along a direction transverse to the flow direction, the electrodes being disposed a two-dimensional array including outer electrodes cooperatively defining an outer boundary of the array and inner electrodes disposed within the boundary;
• (c) a three-phase electrical power supply having three poles, the power supply being operable to supply alternating potentials offset by 120° in phase to the respective poles;
• (d) power switches electrically connected between at least some of the plurality of electrodes and the poles, the power switches being operable to selectively connect each of the electrodes to one or another of the poles and to selectively disconnect each of the electrodes from the poles so as to form current paths extending through the liquid disposed in the chamber between electrodes connected to different ones of the poles;
• and
• (e) a control processing unit coupled to the power switches and configured to actuate the power switches according to switch setting data retrieved from a memory, the memory storing a plurality of predefined connection schemes;
• wherein the connection schemes include electrode groupings having three-fold symmetry about a central axis and define current paths between pairs of poles of the three-phase power supply with substantially equal specific resistance.

A liquid heater comprising:

• (a) a chamber;
• (b) a plurality of rod-like electrodes disposed within the chamber and extending substantially parallel to one another, the electrodes being disposed a two-dimensional array;
• (c) a three-phase electrical power supply having three poles, the power supply being operable to supply different electrical potentials to different ones of the poles;
• (d) power switches electrically connected between at least some of the plurality of electrodes and the poles, the power switches being operable to selectively connect each of the electrodes to one or another of the poles and to selectively disconnect each of the electrodes from the poles so as to form current paths extending through liquid disposed in the chamber between electrodes connected to different ones of the poles and
• (e) a control processing unit coupled to the power switches and configured to actuate the power switches based on switch setting data retrieved from a memory, the memory storing a plurality of predefined connection schemes, wherein the connection schemes include groupings of electrodes defining current paths having three-fold symmetry about a central axis and substantially equal specific resistances between the poles of the three-phase power supply;
• wherein the electrodes are arranged in a hexagonal array including outer electrodes cooperatively defining an outer boundary of the array in the shape of a regular hexagon and inner electrodes disposed within the boundary and defining at least one inner hexagon, the array including rows extending along three sets of row axes disposed at 60° angles to one another, the row axes in each set being uniformly spaced and the spacings between row axes of the three sets being equal to one another, the row axes intersecting one another to form a grid of equilateral triangles, the electrodes being disposed at the vertices of the equilateral triangles, the power switches being operable to connect three sets of the electrodes to the respective poles so that the electrodes connected to the poles have three-fold symmetry around a central axis and define current paths between the poles having three-fold symmetry around the central axis.