Pressurized bellows flat contact heat exchanger interface

Disclosed is an interdigitated plate-type heat exchanger interface. The interface includes a modular interconnect to thermally connect a pair or pairs of plate-type heat exchangers to a second single or multiple plate-type heat exchanger. The modular interconnect comprises a series of parallel, plate-type heat exchangers arranged in pairs to form a slot therebetween. The plate-type heat exchangers of the second heat exchanger insert into the slots of the modular interconnect. Bellows are provided between the pairs of fins of the modular interconnect so that when the bellows are pressurized, they drive the plate-type heat exchangers of the modular interconnect toward one another, thus closing upon the second heat exchanger plates. Each end of the bellows has as a part thereof a thin, membrane diaphragm which readily conforms to the contours of the heat exchanger plates of the modular interconnect when the bellows is pressurized. This ensures an even distribution of pressure on the heat exchangers of the modular interconnect thus creating substantially planar contact between the two heat exchangers. The effect of the interface of the present invention is to provide a dry connection between two heat exchangers whereby the rate of heat transfer can be varied by varying the pressure within the bellows.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to heat exchangers and more particularly 
to contact interfaces between two heat exchangers. 
2. Background Art 
There is taught a thermal operated circuit controlling device in U.S. Pat. 
No. 2,109,169. The device provides for adjustment of the time of operation 
of bi-metallic thermal elements enclosed in an evacuated or gas filled 
bulb. A diaphragm is provided as a means of varying the pressure within 
the device for the purpose of adjusting the operating time of a thermally 
operated circuit controller. 
In U.S. Pat. No. 3,225,820 there is taught a device for maintaining the 
operating temperature of an electronic component by controlling the rate 
at which the heat generated within the component is allowed to dissipate. 
A bellows containing an expansive medium expands and contracts to vary an 
air gap, the bellows itself serving as a heat conductor and the width of 
the air gap serving to control the resistance to heat dissipation. 
A heat valve is taught in U.S. Pat. No. 3,391,728. The heat valve is formed 
in the gap between the heat source and a heat sink. The gap is capped on 
one end by a pressurized gas reservoir and on the opposite end by a 
bellows containing a liquid thermal conductor. By varying the level of the 
liquid thermal conductor, the conduction of heat across the gap can be 
controlled. 
In U.S. Pat. No. 3,450,196 there is taught an apparatus which uses gas 
pressure control to vary thermal conductivity. A heat radiating component 
is surrounded with multiple layers of thermal insulation with the outer 
layer of the thermal insulation being a pressurizable container. Gas or 
liquid may be passed between the layers of thermal insulation and by 
varying the pressure of the gas or liquid, the thermal conductivity of the 
gas or liquid is varied resulting in a regulation of the heat loss of the 
component. 
In U.S. Pat. No. 3,463,224 there is described a heat transfer switch which 
utilizes a contained fluid, a bellows and heat conducting plate. As the 
temperature of the fluid is increased, it expands filling the bellows with 
the bellows in turn elongating and driving one thermal conducting plate to 
contact another. 
In U.S. Pat. No. 3,478,819 there is taught a variable heat conductor for 
use in space vehicles. A thermal responsive element is used to drive an 
actuator causing a piston to contact a heat sink. 
A thermal coupling device for use in cryogenic refrigeration is taught in 
U.S. Pat. No. 3,807,188. The device incorporates a mercury filled bellows. 
When the mercury freezes the bellows clamps around a thermal transfer 
neck, thus providing a coupling between a refrigerant source and a device 
to be refrigerated. 
A double tube heat exchanger is taught in U.S. Pat. No. 3,907,026. The heat 
exchanger is conventional in that heat is transferred from a primary fluid 
to a secondary fluid. The tubes through which the fluids flow are 
interdigitated. 
Building panels having controllable insulating capabilities are taught in 
U.S. Pat. No. 3,920,953. The panels comprise a pair of walls which can be 
moved toward or away from each other to vary the insulating properties of 
the panels. Air is used to inflate flexible ducts residing between the 
walls, thus driving the walls further apart to increase the insulating 
properties of the panel. Deflating the flexible ducts draws the walls 
together and decreases the insulating properties of the panel. 
U.S. Pat. No. 3,957,107 teaches yet another thermal switch connecting a 
heat sink to a heat source. An expandible bellows encloses a refrigerant. 
As the bellows assembly is heated, the refrigerant vaporizes expanding the 
bellows and connection the heat circuit between the heat sink and the heat 
source. 
yet another heat controlling device utilizing a bellows arrangement is 
taught in U.S. Pat. No. 4,454,910. As with some other patents discussed 
above, the bellows encloses a working fluid with a relatively high vapor 
pressure As the working fluid is heated, the resultant vapor pressure 
causes the bellows to expand thereby driving a contact plate toward a 
radiating plate. Heat from a heat source is then transmitted through the 
working fluid and the contact plate to the radiating plate. 
Although it can be seen that heat transfer devices have incorporated 
bellows to drive contacting plates together to complete a heat circuit, 
the use of a bellows has not been incorporated to drive multiple 
plate-type heat exchangers into contact with a second plate-type heat 
exchanger in an interdigitated arrangement. Further, nowhere has there 
previously been used a thin membrane diaphragm forming an end portion of 
the bellows to allow the surface of the membrane diaphragm to conform to 
any contours in the heat exchanger plates thereby applying a uniform 
contact pressure between the heat exchangers. The result is a dry, 
efficient heat transfer where the rate of heat transfer can be varied by 
varying the pressure within the bellows. 
SUMMARY OF THE INVENTION 
Accordingly, it is therefore an object of the present invention to provide 
an apparatus for thermally coupling two interdigitated plate-type heat 
exchangers. 
A further object of the present invention is to provide an apparatus for 
heat transfer between two fluid loops without using fluid connections. 
Another object of the present invention is to provide a bellows driven 
conformable membrane diaphragm which when pressurized drives the plates of 
two interdigitated plate-type heat exchangers into contact interface. 
Still another object of the present invention is to form the area of the 
bellows in contact with the plates of the heat exchangers as a thin 
membrane diaphragm which conforms to the surface contours of the attached 
plate so that a uniform pressure is applied to the plate thus ensuring 
substantially full planar contact between interfacing plates. 
Briefly stated, the foregoing and numerous other features, objects and 
advantages of the present invention will become readily apparent upon a 
reading of the detailed description, claims and drawings set forth 
hereinafter. These features, objects and advantages are accomplished by 
providing for an interdigitated heat exchanger interface between two heat 
exchangers. In essence, a male/female type connection is made between a 
first heat exchanger surface and a modularized interconnect containing the 
second heat exchanger surface. The plates of the first heat exchanger are 
inserted into the slots created in the modularized interconnect between 
pairs of heat exchanger plates of the modularized interconnect. 
A pressurized bellows arrangement is provided to drive the heat exchanger 
plates into substantially full planar contact with one another, thus 
providing a dry, efficient, thermal contact conduction interface between 
two heat exchangers. Each bellows arrangement features a thin membrane 
diaphragm forming a part of the pressurized bellows where the pressurized 
bellows attaches to the plates of the modularized interconnect. As the 
bellows are pressurized, the thin diaphragm conforms to the surface 
contours of the attached plate to provide efficient heat transfer. By 
varying the pressure of the fluid within the bellows, the thermal contact 
conductance and thus, the rate of heat transfer can also be varied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Turning first to FIG. 1, there is shown a modularized heat exchanger 
interconnect 1 and a set of heat exchangers 3. Modularized interconnect 1 
contains the plates 5 of a plate-type heat exchanger. The plates 5 are 
arranged in pairs within containment structure 7. Plates 5 are rectangular 
and form an array of spaced pairs of plates 5. A slot 9 is present in 
between the plates 5 of each pair. Also housed within containment 
structure 7 are a plurality of bellows 11. Each bellows 11 attaches to two 
plates 5 on the faces of plates 5 opposite slots 9. The ends of each 
bellows 11 are provided with a plurality of peripheral projections 12 with 
apertures 14 therein. Screws or bolts 16 extend through apertures 14 to 
attach bellows 11 to plates 5. The end portions of each bellows 11 which 
contact plates 5 are thin membrane diaphragms 13. The ends 15 of 
containment structure 7 enclose a perforated honeycomb structure 17 which 
pressurizes simultaneously with bellows 11 during operation to provide 
lateral containment support within containment structure 7. Perforated 
honeycomb structure 17 is preferably an open celled metallic honeycomb. 
The bellows material is chosen depending upon the service an conditions 
under which the interface is operated. Contingent on such factors, the 
bellows material may range from steel to titanium. Thickness of the 
membrane diaphragm 13 is governed by the conformability under pressure of 
the particular material chosen. For example, if titanium is the chosen 
bellows material, it has been found that a thickness of 0.01 inches is 
acceptable for membrane diaphragms 13. 
Modular interconnect 1 is provided with a pressurized fluid manifold 19 
connected to each bellows 11 by means of flexible conduits 21. Manifold 19 
also connects to perforated honeycomb pressurized end structures 17 by 
means of conduits 23. 
Heat exchanger 3 is comprised of a plurality of rectangular heat exchanger 
plates 25 extending from a support plate 27. Rectangular plates 25 are the 
first heat exchanger which may, for example, be an ammonia heat exchanger. 
Plates 5 located within containment structure 7 are the second heat 
exchanger which may be, for example, a water heat exchanger. 
In operation, plates 25 insert into slots 9 of modular interconnect 1, thus 
creating a dry, flat contact heat exchanger interface. Bellows 11 and 
perforated honeycomb end structures 17 are pressurized with fluid, for 
example nitrogen, through manifold 19. As bellows 11 are pressurized, they 
expand driving plates 5 into contact with plates 25. Thin membrane 
diaphragm 13 which forms the end portions of bellows 11 conforms to the 
surface contours of attached plate 5, thus ensuring a uniform pressure 
exerted on plates 5. The result is a uniform pressure thermal contact 
conduction interface between plates 5 and plates 25. The thermal contact 
conductance and therefore, the rate of heat transfer can be varied by 
varying the pressure of the fluid to the bellows 11 and perforated 
honeycomb end structures 17. The greater the pressure, the greater the 
conductance. The metallurgy of plates 5 and 25 may be any metallurgy 
typically used in plate-type heat exchangers such as, for example, steel 
or aluminum. 
From the foregoing, it can be seen that the flat contact heat exchanger 
interface of th present invention provides an efficient and dry means of 
providing a contact interface between two heat exchangers. Clearly the 
interface of the present invention is advantageous over a typical 
connectable/disconnectable fluid interface which provides many 
opportunities for leaks to occur. This advantage becomes more apparent 
when it is realized that quite often the fluids contained within the heat 
exchangers are corrosive requiring a special metallurgy. With the present 
invention, if one of the fluids is corrosive, only that heat exchanger 
containing the corrosive fluid be made of the required special metallurgy. 
The second heat exchanger containing the non-corrosive fluid need not be 
manufactured from a special metal because the interface between the two 
heat exchangers is dry. 
Yet another advantage of the present invention is the modularized 
interconnect which allows one heat exchanger to be easily replaced without 
disturbing the second heat exchanger. This situation could develop for 
example, when one heat exchanger develops leaks or becomes fouled. Other 
than disconnecting the interface between the two exchangers, all other 
connections, fluid or otherwise, to the non-leaking exchanger may remain 
in place. Replacement of the leaking or fouled heat exchanger thus becomes 
both cost and time efficient as a result of the dry modularized interface. 
An additional advantage of the interface of the present invention is the 
capability of varying heat loads or changing thermal flow loops while 
maintaining a constant fluid flow condition of a central thermal transport 
loop. The bellows pressure can be reduced so that contact between plates 5 
and 25 is no longer maintained, thereby eliminating heat transfer without 
shutting down circulating pumps or closing valves. Similarly, the 
temperature control of a fluid loop can be regulated by a variation of 
bellows pressure which, as stated above, affects the heat transfer rate 
across the exchanger interface. 
From the foregoing, it is seen that this invention is one well adapted to 
attain all of the ends and objects hereinabove set forth, together with 
other advantages which are obvious and which are inherent to the 
apparatus. 
It will be understood that certain features and subcombinations are of 
utility and may be employed with reference to other features and 
subcombinations. This is contemplated by and is within the scope of the 
claims. 
As many possible embodiments may be made of the invention without departing 
from the scope thereof, it is to be understood that all matter herein set 
forth or shown in the accompanying drawings is to be interpreted as 
illustrative and not in a limiting sense.