Heat exchange – Three non-communicating fluids
Reexamination Certificate
2000-09-08
2001-10-23
Flanigan, Allen (Department: 3743)
Heat exchange
Three non-communicating fluids
C165S167000, C165SDIG003
Reexamination Certificate
active
06305466
ABSTRACT:
This invention relates to a three circuit plate heat exchanger.
Heat exchangers having three circuits are used where it is desirable to have a single fluid flow to exchange heat with two separate fluid flows. E. g. a flow of water may be used for evaporating or condensing two separate flows of refrigerant.
Plate heat exchangers are widely used also for exchangers having three circuits of heat exchanging media due to their low volume, weight and manufacturing cost relative to their efficiency. The plates are defining almost parallel channels for the three flows of media and are generally sealed and interconnected by brazing or soldering—preferably by vacuum brazing—although even welding or gluing may be used.
Known types of currently used three circuit heat exchangers have been described e. g. in WO 95/35474 and in WO 97/08506. The objects are to design plate heat exchangers which are reliable in use—i.e. the sealing of the channels for the heat exchanging media should remain intact during the life time of the exchanger—and to keep the manufacturing cost low.
The WO 95/35474 relates to a heat exchanger in which the plates defining the channels for the flows of the three heat exchanging media are provided with three pairs of holes defining ports connecting the inlets and the outlets of each of the three flows of fluids with the channels between the plates of the exchanger. In order to prevent each of the entering flows of fluids from passing into channels which should be passed only by the remaining two flows, said channels are blocked at the ports for each flow by interconnecting adjacent plates by brazing at ring shaped areas at the port defining holes. According to WO 95/35474 the brazing is established at ring shaped areas around the port holes having substantially different sizes. This may cause problems during the brazing operation. Also the effective plate area will decrease.
The WO 97/08506 shows a way of blocking channels from entrance of fluid from the actual port hole by use of ring shaped space between certain plates to ensure that all brazing at ring shaped sealing areas at each port hole may be performed at substantially uniform inner and outer diameters. However, this solution is more expensive and more heavy due to the extra weight of the spacers.
The present invention relates to a three circuit plate heat exchanger comprising
at least ten stacked plates provided with a pressed pattern defining channels for three different flows of heat exchanging fluids; where
at least six of the said stacked plates defining channels are provided with six holes;
all said channel defining plates are of equal outer dimensions, the said holes having identical locations in all plates;
the said channel defining plates having six holes are interconnected by means comprising brazing, soldering, welding or gluing at ring shaped contact areas adjacent to the holes, as well as at their outer periphery.
The present invention has for its object to provide a plate heat exchanger of the above type combing the possibility of obtaining a reliable interconnection and a low cost manufacture.
According to the present invention this is obtained thereby that said ring shaped areas of the plates adjacent to four of the said six holes are of substantially equal outer and inner shapes, the areas adapted to contact a neighboring plate at two of the holes in a plate being displaced away from a plane containing the contact areas around the remaining four holes in the plate through a distance which is about twice the distance through which the remaining, to the greatest extent displaced channel defining material in the plate has been displaced.
REFERENCES:
patent: 2617634 (1952-11-01), Jendrassik
patent: 5180004 (1993-01-01), Nguyen
patent: 5462113 (1995-10-01), Wand
patent: 6164371 (2000-12-01), Bertilsson et al.
Andersson Sven
Dahlberg Thomas
Breiner & Breiner L.L.C.
Flanigan Allen
SWEP International AB
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