Electric Heating System for Heating a Fluid Flow

An electric heating system for heating a fluid flow, the system comprising:

• a housing having an inlet for a fluid flow to be heated by the electric heating system and an outlet for the fluid flow which has been heated by the electric heating system;
• and
• a resistive heater mounted within the housing, the resistive heater comprising:
• a fluid input and a fluid output which are fluidically coupled, respectively, to the inlet and the outlet,
• a plurality of annular walls composed of an electrically conductive material, the walls being nested to define a plurality of annular flow channels which are serially arranged concentrically about a longitudinal axis, wherein the walls extend between opposite first and second ends of the resistive heater which are mutually separated along the longitudinal axis, and
• first and second electrical terminals for connection to a source of electrical energy to heat the walls of the resistive heater, the first and second electrical terminals being electrically connected to respective first and second walls which are mutually adjacent and comprise an outer pair of the walls which are located at a radially outer side of the resistive heater,
• wherein the plurality of annular walls are mechanically connected together whereby adjacent flow channels have opposite fluid flow directions and are connected at adjacent ends of the respective channels to define an alternating serpentine flow path which has an input end at the fluid input and an output end at the fluid output, wherein the input and output ends are respectively located at radially outer and radially inner positions relative to the longitudinal axis, and
• wherein the plurality of annular walls are electrically connected together to define a continuous electrically conductive path extending between the first and second electrical terminals, the conductive path having a first part which extends from the first wall to a centre of the resistive heater and a second part which extends from the centre of the resistive heater to the second wall.