Heat exchange – Flow passages for two confined fluids – Interdigitated plural first and plural second fluid passages
Patent
1989-12-06
1990-10-30
Schwadron, Martin P.
Heat exchange
Flow passages for two confined fluids
Interdigitated plural first and plural second fluid passages
165166, F28F 310, F28F 308
Patent
active
049662279
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a plate heat exchanger comprising a package of heat exchange plates, each of which is elongated and substantially rectangular and has a central heat exchange portion and corner portions provided with ports; an inlet member connected both to a source for liquid to be at least partly evaporated in the plate heat exchanger, and to a first channel through the package of heat exchange plates, which is formed by aligned ports in the heat exchange plates, in- and outlet members connected both to a source and a reception place, respectively, for a heating medium and to two other channels through the package of heat exchange plates, which channels are formed by aligned ports in the heat exchange plates on each side of the central heat exchange portions of the heat exchange plates, said first channel communicating with only every second interspace between the heat exchange plates, while the other two channels communicate with the other interspaces between the heat exchange plates; and sealing means arranged between adjacent heat exchange plates such that said liquid and the heating medium during operation of the plate heat exchanger are allowed to flow substantially in parallel through the plate interspaces in the longitudinal direction of the heat exchange plates, either concurrently or countercurrently.
Plate heat exchangers of the above described general kind are known and used since at least 50 years. They are used for many different heat exchange duties, such as for evaporation of liquids.
In connection with evaporation of a liquid there is a problem in that the steam released from the liquid has a volume that is many times larger than the volume of the liquid out of which the steam has been formed. This means that those ports of the heat exchange plates which are to form an outlet channel through the plate package for the formed steam and possibly remaining liquid have to be made very large in order that the outlet channel should not create a too large through-flow resistance for the steam. Such a particular shape of the heat exchange plates, and a necessary adaptation thereto of other parts of the plate heat exchanger, makes the production of the whole plate heat exchanger expensive.
In U.S. Pat. No. 3,201,332 (corresponding to SE 200.605) a solution to the above discussed problem was suggested. The solution resided in use of conventional heat exchange plates with relatively small ports in all of the four corners, an outlet opening for the formed steam and possibly remaining liquid being created by omission of the sealing means in every second plate interspace along the upper part thereof. An advantage of this solution was that already available heat exchange plates produced for other heat exchange duties could be used also in connection with evaporation of liquids.
In U.S. Pat. No. 3,201,332 there is described in detail only one embodiment of the suggested plate heat exchanger, in which the long sides of the plates extend horizontally. The reason therefore is that the outlet openings from the plate interspaces for the at least partly evaporated liquid, which openings are situated at the top, should be made as large as possible to offer as small a flow resistance as possible. Possibly, the inventor in question has noticed that the flow resistance in the outlet openings would have become undesirably large, if the heat exchange plates had been arranged with their long sides extending vertically and, thus, the outlet opening from every second plate interspace had been created by omission of the sealing means only along the upper short sides of the heat exchange plates.
However, by arranging the heat exchange plates with their long sides extending horizontally and by having the outlet openings for the at least partly evaporated liquid extending along the upper whole long sides of the plates the inventor has changed the heat exchange conditions, for which the heat exchange plates in question were originally calculated. Thus, the flow conditions concerning for instance the pressure
REFERENCES:
patent: 3042382 (1962-07-01), Hoyniszak
patent: 3850234 (1974-11-01), Fowler
patent: 4184542 (1980-01-01), Sumitomo
patent: 4291754 (1981-09-01), Morse et al.
patent: 4296803 (1981-10-01), Sumitomo
patent: 4373579 (1983-02-01), Jernqvist
Alfa-Laval Thermal AB
Flanigan Allen J.
Schwadron Martin P.
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