US 3490523 A
Description (OCR text may contain errors)
Jan. 20, 1970 w. G. ESMOND TRANSFERDEVICE Filed April 8, 1968 WQLLMM G. ESMOND ATTORNEY United States Patent U.S. Cl. 165-166 11 Claims ABSTRACT OF THE DISCLOSURE This disclosure relates to a transfer device which includes a centrally disposed envelope having secured to opposite sides thereof in sealed relation a pair of flow sheets. Each flow sheet has a plurality of longitudinal channels which open towards the respective face of the envelope throughout the lengths of the channels whereby a first fluid may flow through the envelope and a second fluid may flow through the channels of the flow sheet. The envelope is formed of a flexible material and when clamped by the flow sheets, a plurality of individual channels is formed within the envelope. The channels of the flow sheets are preferably of the sine-cosine configuration. The transfer device, depending upon the material from which the envelope is formed, may be utilized as a heat exchanger, an artificial kidney or an artificial lung or gill.
This invention relates in general to new and useful improvements in transfer devices, and more particularly to a novel transfer device which may be used as an exchanger of all types both in the industrial and medical fields. The transfer device includes a central envelope through which a first fluid flows and the material of which envelope is varied in accordance with the desired transfer. The envelope is clamped between two face sheets which have formed therein longitudinally extending channels. The envelope is of a flexible construction and when clamped between the face sheets, the channels of the face sheets automatically form channels within the envelope to provide for a controlled flow :path therethrough. n
A primary object of this invention is to provide a novel transfer device which is of a construction to provide an even flow resistance geometry so that even amounts of two fluids may be constantly and evenly distributed on the opposite sides of a mass transfer or heat exchange surface.
Another object of this invention is to provide a novel transfer device wherein two fluids are passed through an envelope and; on opposite surfaces of the envelope between the envelope and a pair of face sheets, and the face sheets and envelope having formed therein channels which are of the sine-cosine configuration and wherein there is a relative crossing of the channels of the two face sheets and a like crossing of the channels within the envelope whreby there is a constant intermixing of the fluid flowing through the envelope and a constantly changmg relationship between the fluid in the envelope and the fluid passing between the envelope and the face sheets.
Another object of this invention is to provide a novel transfer device which may be utilized as a heat transfer device when the envelope thereof is formed of an impermeable material and at the same time is of a construction whreein when the envelope is in the form of a membrane, the transfer device will have uses in the medical field depending upon the construction of the membrane 7 envelope and the particular fluids passed therethrough.
3,490,523 Patented Jan. 20, 1970 Still another object of this invention is to provide a novel light weight transfer device which can be very inexpensively mass produced.
A still further object of this invention is to provide a novel transfer device wherein the flow sheets are formed of a transparent material and the envelope is in the form of a membrane whereby the passage of bubbles through the membrane may be visually observed so as to visually determine the operation of the transfer device.
With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings.
In the drawings:
FIGURE 1 is an exploded perspective view of the transfer device and shows generally the details thereof.
FIGURE 2 is a schematic single line sectional view taken along the line 22 through one of the flow sheets.
FIGURES 3 and 4 are schematic single line sectional views similar to FIGURE 2 for taking along the lines 3-3 and 44, respectively.
FIGURE 5 is a schematic single line transverse sectional view taken through the entire transfer device along the line 55 of FIGURE 1.
FIGURE 6 is a fragmentary enlargement of FIGURE 5 and shows specifically the details of the transfer device.
Referring now to the drawings in detail, it will be seen that there is illustrated in FIGURE 1 the transfer device which is generally identified by the numeral 10. The transfer device 10 includes a central envelope, which is generally identified by the numeral 11, and through which a first fluid is intended to flow. On opposite sides of the envelope 11 there is clamped a pair of flow sheets 12 and 13. It is intended that a second fluid flow between the flow sheets and the envelope.
Considering first the construction of the envelope 11, it will be seen that it is formed of a pair of sheets 14 and 15 of flexible material which has positioned in the opposite ends thereof flow tubes 16 and 17. The sheets 14 and 15 are bonded together in any suitable manner about the peripheral edges thereof and to the flow tubes 16 and 17 to form a fluid tight seal therewith.
It is to be noted that one end of each of the flow tubes 16 and 17 is open to facilitate either the inlet or discharge of a fluid and the opposite end thereof is closed by means of a suitable plug. In addition, each of the flow tubes 16 and 17 is provided with an elongated slot 18 which opens longitudinally of the envelope 11 so as to provide for the even distribution of fluid across the width of the envelope. For purposes of description, the flow tube 16 is an inlet tube and the flow tube 17 is a discharge tube.
Each of the flow sheets 12 and 13 is formed with a plurality of longitudinally extending channels 20 which open towards the envelope 11 and together with the envelope 11 form flow passages for a second fluid. These channels may vary in cross section, as is clearly shown in FIGURES 2, 3 and 4.
Adjacent the opposite ends of each of the flow sheets 12 and 13 there is provided a pair of transversely extending channels which are preferably of a half cylinder configuration. The channels at each end of each flow sheet 12 and 13 includes an inner channel 21 and an outer channel 22. The channels 21 and 22 of the flow sheets combine to define transverse passages. It will be readily apparent that the channels 21 snugly fit about the flow tubes 16 and 17 and the respective enlarged portions of the envelope 11 while the channels 22 combine to define inlet and discharge passages for the second fluid. At one end of the transfer device, the cooperating pair of channels 22 is provided with an inlet fitting 23 at one end and a plug 24 at the opposite end. The other of the passages defined by the channels 22 is provided with a discharge fitting 25 at one end and a plug 26 at the opposite end.
It is to be noted that the channels 20 extend across the channels 21 and terminate in the channels 22 so that there is fluid flow from one channel 22 across the channels 21 and to the other channel 22. It is also to be noted that the peripheral edges of the flow sheets 12 and 13 are planar whereby a suitable seal may be formed between the flow sheets 12 and 13 and the envelope 11.
It is to be understood that the envelope 11 is to be formed of a suitably flexible material whereby when the envelope 11 is clamped between the flow sheets 12 and 13, not only will there be formed as separate fluid passages between the flow sheets and the envelope within the respective channels 20, but also the envelope will be collapsed between the contacting portions of the flow sheets to form a plurality of individual channels or passages 27 within the envelope. Thus, there is a controlled flow of fluid both within the envelope and between the envelope and the flow sheets.
It has been found that the most efficient configuration of the channels 20 is that of the sine-cosine curve. Furthermore, it has been found to be most effective if the flow sheets 12 and 13 are identical and when disposed in face-to-face relations, the channels 20 thereof are 180 out of phase. With this particular type of construction, the two flow sheets 12 and 13 reinforce one another with the ridges thereof defining the channels 20 crossing one another at regular intervals and preventing relative collapse. In addition, the channels or passages formed in the envelope are disposed in constantly crossing relation with the result that there is produced within the fluid flowing through the envelope a shearing and mixing force which constantly changes the relationship of the fluid passing through the envelope with respect to the envelope and at the same time constantly changes the relationship of the fluid within the envelope relative to that passing around the envelope. This provides for a maximum efliciency in the transfer device.
At this time it is pointed out that although the channels 20 are illustrated as being uniform, it is to be understood that certain of the channels 20 may be of a greater volume than others. By so constructing the flow sheets 12' and 13, a greater priming volume may be provided. The priming volume of the transfer device may initially be accurately controlled.
It is to be understood that fluids are to be passed through the transfer device under pressure. As a result, it is necessary to tightly clamp the flow sheets 12 and 13 against the envelope in addition to sealing the peripheral edges of the flow, sheets to the envelope. Inasmuch as this clamping can be effected in many ways which in of itself is not a part of this invention, there has been no specific illustration of the clamping devices. However, it is desirable to set forth here several illustrative clamping methods. The simplest clamping method would be the 'clamping of the transfer device between a pair of rigid plates. In undersea work the pressure of the water alone has been found sufficient to hold the unit flat and retain its precise geometry. The flow sheets 12 and 13 may be held in clamped relation to the envelope 11 by submerging the transfer device in a pool of mercury. Another method of holding the transfer device together is to fix it between two air filter pressurized bladders which are held together by suitable supports such as two vacuum formed blisters clamped together with an air bladder in each and with the transfer unit clamped between the two air bladders. Further, if the expense of the transfer device Warrants it, the flow sheets 12 and 13 may be formed of a heavy rigid construction so that the flow sheets themselves. o ld resist distortion.
When the transfer device 10 is utilized as a simple heat exchanger, the sheets 14 and 15 of the envelope 11 must be formed of an impermeable material. It has been found that this material may be a thin Teflon film or a Mylar film. In addition, even very thin metal sheets, including silver and stainless steel, may be used to form the envelope. Normally, the fluid whose temperature is to be controlled is passed through the envelope while the heat exchanger fluid is passed between the envelope and the flow sheets.
When the transfer device 10 is utilized as an artificial lung or gill, it is necessary that the envelope 11 be formed of a membrane material which is permeable to the gases (oxygen and carbon dioxide) that must be transported. It has been found that the membrane material best suited for the formation of the sheets 14 and 15 includes a very thin Teflon film, silicon rubber and a newly developed siliconpolycarbonate which has additional strength. In the operation of the artificial lung, venous blood is pumped into the envelope 11 while oxygen is led through the outer compartments between the flow sheets 12 and 13 in the envelope with the oxygen preferably flowing countercurrent to the flow of the blood.
The oxygen diffuses through or dissolves in the material of the envelope 11 and finally is picked up in the blood and oxygenates through the hemoglobin in the red cells of the blood. At the same time, carbon dioxide diffuses out of the blood through the membrane envelope and is swept in a rapid stream of excess oxygen. The oxygenated blood is then returned to the patient into an artery.
When the transfer device 10 is utilized as an artificial kidney, the material of the sheets 14 and 15 of the envelope must be that of a membrane which is selectively permeable to some specific toxin in the blood or be nonselective to diifusible ions and molecules of low molecular weight such as a thin cellulose cellophane member or cellulose member from hydrolized cellulose acetate. In the use of the transfer device as an artificial kidney, a bath solution or electrolyte is passed through the outer compartments defined between the flow sheets 12 and 13 and the envelope while the blood to be treated is pumped through the envelope. This electrolyte is preferably held at a normal temperature of 37.5" C. although the temperature may be slightly varied. The electrolyte is a bath solution containing NaCl, Na acetate, MgCI- KCl, CaCl and glucose in proper concentrations such as Na+ 132 meq./ l., CllOO meq./l., Ca++ 2.5 meq./l., Mg++ 1.5 meq./l, K+ 2 to 4 meq/l. and glucose to 200 mg. percent or more.
The electrolyte is pumped or siphoned by gravity through the outer compartments and recirculated or possibly pased directly down a drain in One pass at the rate of 500 ml./min. The blood is led through the cellulose membrane envelope 11 by arterial pressure or by a pump and after the loss of toxins (uremic or drugs) by dialysis, the blood is led back through the tubing into the patients veins.
At this time it is pointed out that although the preferred pattern of the channels 20 of the flow sheets is preferably that of a sine-cosine cur-ve, it is to be understood that this pattern may be interrupted at intervals or may be slightly modified without varying the spirit and scope of the invention.
It is also pointed out here that while the flow sheets 12 and 1 3 may be formed in any desired manner, it has been found that the flow sheets may be most economically formed from plastic sheet material by a vacuum molding process. When the material of the flow sheets 12 and 13 is a transparent material, the operation of the transfer device, particularly when utilized as either an artificial kidney or an artificial lung, may be readily observed and the rate of bubbling of gases outwardly from the envelope 11 may be visually detected,
Although the flow sheets may be secured to the envelope by any type of sealing medium, it has been found that in many instances where the envelope and the flow sheets are formed of plastic materials, a suitable waterproof cement manufactured by General Electric and identified as RTV118 has proved to be very satisfactory.
Although only a single embodiment of the transfer device has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the transfer device without departing from the spirit and scope of the invention, as defined by the appended claims.
1. A transfer device for fluids comprising an envelope having first fluid inlet and discharge fittings at the opposite ends thereof, and a pair of flow sheets disposed on opposite sides of said envelope and being sealed thereto at least along peripheral edge portions of said envelope, each of said flow sheets having formed therein longitudinally extending channels opening substantially throughout the length thereof to face surfaces of said envelope wherein said channels are of the sine-cosine configuration and the two flow sheets are so positioned that said channels are arranged in crossing relation, and second fluid inlet and discharge fittings at the opposite ends thereof.
2. The transfer device of claim 1 wherein said envelope is flexible with said envelope being clamped between said flow sheet intermediate said channels with intermediate portions of said envelope projecting into said channels and forming longitudinal flow passages in said envelope.
3. The transfer device of claim 1 wherein said channels of the two flow sheets are 180 out of phase.
4. The transfer device of claim 1 wherein said flow sheets define at each end thereof two transverse assages, inner ones of said transverse passages receiving said first fluid inlet and discharge fittings, and outer ones of said transverse passages forming parts of said second fluid inlet and discharge means, and said longitudinal channels extending across said inner transverse passages and terminating in said outer transverse passages.
5. The transfer device of claim 1 wherein said envelope is in the form of a membrane capable of limited predetermined fluid flow therethrough.
6. The transfer device of claim 1 wherein said transfer device is an artificial kidney and wherein said envelope is in the form of a membrane capable of having passed therethrough by diffusion waste products from blood flowing through said envelope. i
7. The artificial kidney of claim 6 wherein said membrane envelope is formed of a cellulose material selected from a group including cellulose cellophane and hydrolized cellulose acetate.
8. The artificial kidney of claim 6 wherein an electrolyte is passed through said channels.
9. The transfer device of claim 1 wherein said transfer device is an artificial lung with said envelope being formed of a membrane capable of passing gases from blood running through said envelope and delivering oxygen from said channels to blood within said envelope.
10. The artificial lung of claim 9 wherein said membrane is formed of a material from a group including Teflon, silicon rubber and silicon-polycarbonate;
11. The transfer device of claim 1 wherein said transfer device is a heat exchanger and said envelope is formed of an impermeable material.
References Cited UNITED STATES PATENTS 2,735,812 2/1956 Van Hoek 210-321 X 3,216,492 11/ 1965 Weaver -166 X 3,332,746 7/1967 Claff et al 23-2585 3,362,540 1/1968 Bluemle 210-321 3,398,091 8/1968 Greatorex 210-321 X 3,412,865 11/1968 Lantz et a1. 210-321 3,435,893 4/1969 Withers 165-180 X MEYER PERLIN, Primary Examiner T. W. STREULE, Assistant Examiner US. Cl. X.R. 23-2585; 165-46; 210-321