Heat exchange – Flow passages for two confined fluids – Interdigitated plural first and plural second fluid passages
Patent
1994-04-21
1996-06-04
Fox, John C.
Heat exchange
Flow passages for two confined fluids
Interdigitated plural first and plural second fluid passages
165167, F28F 308
Patent
active
055224628
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a plate type heat exchanger, and more particularly to an improved seal between adjacent plates in a plate type heat exchanger. Each such pair of plates will be referred to herein as a "plate pair".
Plate type heat exchangers consist of a number of heat transfer plates which are clamped together in a stack in face to face relationship to define flow channels between the adjacent :plates. Two streams of media each flow through respective sets of alternate channels, the media being in heat exchange contact through the intervening plates. The plates are sealed together at their edges and in the region of two pairs of entry and exit ports provided at the corners of the plates. A pair of ports connects with one set of alternate flow spaces and is sealed from the other set.
Considerable attention has been paid to the seal between adjacent plates. Most typically in the past the outer edges of adjacent plates, and the region around the ports, have been sealed together by gaskets which sit in a groove formed in one of the plates, the groove supporting the gasket against being forced outwards by pressurised medium in the flow space. More recently, the gaskets have been replaced in whole or in part by a permanent joint, such as adhesive, solder, braze, a plastic mould or by welding. This may be done to provide a cheaper seal or to provide increased security against leakage of the medium from between the plates.
In one prior art form of welded seal, a metal gasket is welded into a groove in a plate and is welded to the base of a corresponding groove in the adjacent plate, that corresponding groove carrying an elastomeric gasket which seals between adjacent plate pairs. Such metal gaskets are expensive.
In another prior art form of welded seal, a pair of adjacent plates is arranged with its gasket carrying grooves back to back, the mating bases of the grooves being welded together. A thick elastomeric gasket forms the seal between the pairs of welded plates, the gasket fitting in the facing grooves. This mirror image arrangement results in the formation of a double gap by-pass channel which runs alongside the welded joint and provides a significantly large region of faster flow of the media between the plates compared to the flow in the flow space proper, adversely affecting the performance of the heat exchanger.
According to our invention in a plate pair for a plate type heat exchanger, in which the plate pair comprises first and second plates permanently joined together at an edge region to form a seal, the first plate is provided in the edge region with a groove facing away from the second plate for receiving a gasket to form a seal with a second similar, adjacent, plate pair, and the underside of the groove mates with and contacts a sealing portion of the second plate in a contact region at which the two plates are permanently joined together to form the plate pair with a first by-pass area defined between the plates inboard of the contact region, the groove and the sealing portion are so shaped and arranged that a second by-pass area is defined between the second plate and the first plate of an adjacent, similar, plate pair, and the groove has an inner side-wall which is substantially continuous and which is of fixed or variable height.
By altering the profiles of the first and second plates slightly we are able therefore to provide first by-pass area which is similar to conventional gasketted systems. Since the second by-pass area may be similar to the first by-pass area we are able to achieve similar flow rates between the plates of a plate pair and between adjacent plate pairs. This maintains the performance of a heat exchanger.
A base of the groove may mate with a planar region at the edge of the second plate of the pair, the planar region extending beyond the inner side wall of the groove in the first plate.
The plates are permanently sealed together by welding, brazing, soldering, plastic, or elastomeric seals.
Preferably, the base of the groove in the first plate is positione
REFERENCES:
patent: 4911235 (1990-03-01), Andersson et al.
patent: 4915165 (1990-04-01), Dahlgren et al.
patent: 4966227 (1990-10-01), Andersson
patent: 5291945 (1994-03-01), Blomgren et al.
Kumar Hemant
Lamont Graham A.
APV Corporation Limited
Fox John C.
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