Heat exchange – Flow passages for two confined fluids – Interdigitated plural first and plural second fluid passages
Patent
1997-12-29
2000-07-11
Flanigan, Allen
Heat exchange
Flow passages for two confined fluids
Interdigitated plural first and plural second fluid passages
165916, F28D 900
Patent
active
06085832&
DESCRIPTION:
BRIEF SUMMARY
This invention embodies a plate heat exchanger consisting of a stack of ring-shaped plates of identical size and profile, in which identical plates face each other with their front and rear sides alternately and are welded or soldered at the places where they touch or rest against each other. The fields of application of this heat exchanger are above all refrigeration and freezing with evaporating and condensing media, machine cooling and heat transmission processes in which a medium enters the heat exchanger freely from a container.
In known heat exchangers heat-releasing and heat-absorbing media flow through conduits with an almost constant cross section. This cross section may fluctuate around a mean value, e.g. due to the installation of barriers which increase flow turbulence and are thus intended to improve heat transfer, but it neither falls nor grows continuously during the heat exchange. This holds true for the known shell-and-tube exchangers and for known spiral and plate heat exchangers.
The guiding principle for heat exchangers is to accommodate the largest possible heat exchange surfaces in the smallest possible space and to attain high heat transmission values while minimizing pressure losses.
In the DE-PS 669442 and 862757 this principle is implemented by plates arranged in successive layers between which a conduit describing a spiral is arranged for each medium involved in the heat exchange. The media are forced to flow down the whole length of the conduits. This does not permit steady heat transfer with a high degree of efficiency in heat transmission, since the laminar flow which forms produces a boundary layer on the walls, which hinders heat transfer.
To improve heat transfer, overflow openings have been included in the spiral-wound partition walls (DE-PS 2615977) or axially in every other plate of the heat exchanger (DE-PS 3210168). The manufacturing input and consumption of materials, however, is very high for such heat exchangers, while the steps taken do not substantially increase the degree of efficiency.
The heat exchanger according to DE-OS 3327828 was to reduce the weight to such an extent as to permit consideration of its use in space. One medium is channelled down a spiral tube, while the other medium flows radially around this tube from the periphery to the centre where the pressure is lower than at the periphery. In this heat exchanger too, the laminar flow predominates in the tubes and heat exchange is relatively low. When it was realized that turbulence is conducive to heat transfer, the flow was made more turbulent by fitting barriers.
In plate heat exchangers, this was achieved mainly through the profile of the plates, as described, for example, in DE-OS 4020757. The profile usually consists of a wave-shaped imprint with wave peaks and wave valleys of identical cross section transverse to the waves' direction of spread. The wave-shaped profiles describe a straight line and form a sharp angle with the longitudinal axes of the plates, so that for plates positioned at 180.degree. to each other the waves cross and keep the plates apart. The medium flowing in the gap formed between the plates undergoes constant changes of direction and the flow cross section varies periodically. This produces larger heat exchanger surfaces and greater turbulence, which both improve heat transfer. The profiles additionally increase the stability of the plates, so that the latter can be made very thin. This is likewise conducive to heat transfer.
These benefits have been exploited in plate heat exchangers for regenerative gas turbines, e.g. according to U.S. Pat. No. 3,424,240. In heat exchangers of this type, a stack of corrugated, ring-shaped heat exchanger plates bounds a central inlet for the hot turbine exhaust gases. These exhaust gases flow radially between pairs of plates, which in turn have cool compressor air flowing round them in the counterflow, to an outlet at the periphery, which is connected to the turbine combustion chamber. The plates are corrugated to improve the heat exchange
REFERENCES:
patent: 1325637 (1919-12-01), Harrison
patent: 2217316 (1940-10-01), Kallstenius
patent: 2251066 (1941-07-01), Persson et al.
patent: 4535840 (1985-08-01), Rosman et al.
patent: 5179999 (1993-01-01), Meekins et al.
patent: 5203832 (1993-04-01), Beatenbough et al.
patent: 5343936 (1994-09-01), Beatenbough et al.
patent: 5472045 (1995-12-01), Poehlman
Steinmetz, W.: Der Evolventenwarmeubertrager--ein neues Konstruktionsprinzip des Ol-Wasser-Warmeubertragers. In: Kraftfahrzeutechnik Feb. 1972, S. 50-52.
Flanigan Allen
Kasper Horst M.
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