Liquid heater with temperature control
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.
1. A fluid handling device comprising:
(a) a channel structure defining a channel extending in a downstream direction;
(b) an elongated temperature-sensing wire extending across the channel in a widthwise direction transverse to the downstream direction, and adjacent a downstream end of the channel; and
(c) an exit structure bounding the channel at a downstream end of the channel, the exit structure defining a slot extending across the channel in the widthwise direction in alignment with the wire, the slot having a cross-sectional area smaller than the cross-sectional area of the channel, the slot being open for flow of fluid exiting from the channel, the exit structure further defining a pair of collection chambers disposed on opposite sides of the slot and offset from the slot in lateral directions transverse to the downstream direction and widthwise direction, and a pair of elongated lips extending in the widthwise direction and separating the chambers from the slot, the collection chambers being open in the upstream direction and extending downstream from the lips, the exit structure further defining exit bores communicating with the collection chambers and open for flow of fluid exiting from the channel, the exit bores collectively having cross-sectional area smaller than the cross-sectional area of the slot.
2. A device as claimed in claim 1 wherein said wire extends within the slot.
3. A device as claimed in claim 1 wherein each of the chambers has an inner bounding wall defined by one of the lips, the inner bounding wall sloping away from the slot in one said lateral direction along the downstream extent of the bounding wall.
4. A device as claimed in claim 3 wherein each of the chambers has an outer bounding wall remote from the slot and sloping toward the slot along the downstream extent of the outer bounding wall.
5. A device as claimed in claim 1 wherein each of the chambers has bounding walls generally in the form of a half of a circular cylinder having an axis extending in the widthwise direction.
6. A device as claimed in claim 1 wherein said channel is generally rectangular in cross-section and wherein said exit chambers and said slot cooperatively extend over substantially the entire cross-sectional area of the channel.
7. A device as claimed in claim 6 wherein the channel structure defines a plurality of channels extending side-by-side and offset from one another in the wire direction, the wire extends across said plurality of channels, and the exit structure defines a slot, collection chambers and exit bores as aforesaid for each said channel.
8. A device as claimed in claim 7 wherein the channel structure includes one or more heating elements associated with each said channel.