Liquid heater with temperature control

摘要

A liquid heater such as a direct electrical resistance liquid heater having multiple flow channels is provided with a temperature-sensing element in the form of a wire extending across numerous channels, preferably all of the channels, near the downstream ends of the channels. The resistance of the wire represents the average temperature of the liquid passing through all of the channels, and hence the temperature of the mixed liquid exiting from the heater. A bubble suppressing structure is provided in the vicinity of the wire.

主权项

1. A fluid heater comprising:
(a) a channel structure defining an inlet, an outlet and a plurality of channels extending in a downstream direction and communicating with the inlet and outlet so that fluid can flow in parallel though the channels from the inlet to the outlet, the channel structure including one or more electrical energy application elements associated with each channel; (b) a temperature-sensing wire extending across the plurality of channels adjacent downstream ends thereof and in a direction transverse to the downstream direction; and (c) a control circuit connected to the electrical energy application elements and the wire, the control circuit being arranged to monitor an electrical resistance of the wire and control application of power to the electrical energy application elements responsive to the electrical resistance of the wire so as to maintain fluid flowing through the outlet at a temperature near a set point, the control circuit being operative to control said application of power so that in at least some control conditions, fluid flowing through different ones of the channels will be heated to different temperatures.