Heat exchange – Flow passages for two confined fluids – Interdigitated plural first and plural second fluid passages
Patent
1997-02-21
1998-07-14
Rivell, John
Heat exchange
Flow passages for two confined fluids
Interdigitated plural first and plural second fluid passages
165166, 165174, F28F 308
Patent
active
057789754
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention refers to a plate heat exchanger for heat transfer between two fluids, comprising several permanently joined modules, each consisting of two outer heat transfer plates and between them several principally rectangular inner heat transfer plates, which have openings for respective fluids in their corner portions, to form flow passages through the plate heat exchanger, said outer heat transfer plates showing smaller openings for at least one of the fluids than said inner heat transfer plates and said modules being joined to each other around said openings in respective outer heat transfer plates.
BACKGROUND OF THE INVENTION
It has until now not been possible to let the fluid flow in several passes through a permanently joined plate heat exchanger constructed of modules. The flow in several passes can be attained by delimiting several sections of heat transfer plates from each other, in which the fluid first flows through one section and subsequently in series flows through the remaining sections. The definition of a pass comprises a flow path from one of the flow passages, through several parallel plate interspaces, to the other flow passage. In several passes the fluid consequently flows back and forth between the flow passages.
However, it is previously known in a conventional plate heat exchanger, provided with gaskets, to let one of the fluids flow through the plate heat exchanger in several passes. For instance, in GB 1522369 such a plate heat exchanger is shown, in which two passes are provided by leaving one or several heat transfer plates non perforated, i.e. the portion of a heat transfer plate that normally is cut away, to make an inlet opening, has been kept. The plate heat exchanger, which is of conventional kind, comprises gaskets between each pair of heat transfer plates and can thus be taken apart. The heat transfer plates can optionally be replaced by non perforated plates.
In the plate heat exchanger, described in the preamble, non perforated plates cannot be used to achieve several passes. That is because the permanently joined modules are joined to each other around the openings in respective outer heat transfer plates. A problem would appear during welding of several non perforated modules.
SUMMARY OF THE INVENTION
The objects with the present invention are to make it possible, in a plate heat exchanger of the above mention kind, to join modules safely, simultaneously as the plate heat exchanger can be adapted to a flow in several passes.
These objects are attained with the present invention, which principally is characterized in that at least one of the fluids is arranged to flow through the plate heat exchanger in several passes, and that at least a disc of a pass is introduced in at least one flow passage and is arranged towards two outer heat transfer plates joined with each other to essentially close said opening.
To be able to assemble the disc of the pass, an imaginary straight line from the periphery of the disc of the pass through its centre, should have a length, which is shorter than the diameter of the openings in the outer heat transfer plates in at least one direction. This can be attained in that the disc of the pass is essentially circular, with a diameter, which exceeds the diameter of the openings in the outer heat transfer plates, and in that the disc of the pass has a recess, in which an outer heat transfer plate partly can be inserted, and that the distance from the bottom of the recess to the periphery of the disc of the pass in all directions is shorter than the diameter of the openings in the outer heat transfer plates.
By reason that an accumulation of air should not prevent the fluid to reach the plate interspaces closest to the disc of the pass it may, in an upper flow passage, be orientated in such way that the recess is turned upwards, forming an upper slot for ventilation of the flow passage.
Similarly, the fluid should not be left in the plate heat exchanger at drainage of the same, and therefore the disc of
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patent: 4090556 (1978-05-01), Almqvist
patent: 4386652 (1983-06-01), Dragojevic
patent: 4396002 (1983-08-01), Lipets
patent: 4813478 (1989-03-01), Jonsson et al.
patent: 5400853 (1995-03-01), Wolters
patent: 5435383 (1995-07-01), Rajagopal
PCT Int. Search Report.
Alfa Laval AB
Atkinson Christopher
Rivell John
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