US2175376A - Method of and apparatus for converting heat - Google Patents

Description

Oct. 10, 1939. v. BUSH ET AL 2,175,376

METHOD OF AND APPARATUS FOR CONVERTING HEAT Filed Nov. 21, 1955 3 Sheets-Sheet l I NVEN'FD S:

0d. 10, 1939. v BUSH ET AL 2,175,376

IBTHOD OF AND APPARATUS FOR CONVERTING HEAT Filed Nov. 21, 1935 s Sheets-Sheet 2 fF -l Oct. 10, 1939. v. BUSH ET AL IBTHDD OF AND APPARATUS FOR CONVERTING HEAT Filed Nov. 21, 1935 3 Sheets-Sheet 3 INQ ENJU Rs:

f. QM

- WALQQQM 25 to a sink, where it is dumped or dissipated.

Patented Oct.10,1939

7 METHOD OF AND APPARATUS FOR CONVERTING HEAT Vannevar Bush, Belmont, Mass., and Edwin L. Rose, Waterbury, Conn., assig'nors, by mesne assignments, to Research Corporation, New York. N. Y., a corporation of New York Application November 21, 1935, Serial No. 50.918

13 Claims.

In a prior application Serial No. 31,859, filed July 1'7, 1935. by Vannevar Bush, are described a method and apparatus for directly utilizing heat energy for the purpose of efiecting the transfer of gas from a region of relatively low pressure to a region of relatively high pressure without the interposition of mechanical power, the apparatus employed being conveniently termed a compressor" or gas pump. In another application,

Serial No. 45.553. filed October 18, 1935, now ma tured into Patent No. 2,127,286, by the same applicant, are described a method and apparatus for util zing the same or similar principles to effect the transfer of heat from one region to another of higher thermal potential, that is to say,

against the direction of normal heat flow, the apparatus employed being conveniently termed a thermal pump". In accordance with the invention described in each of said applications, the

20 energy employed for the accomplishment of the desired result is heat energy, as distinguished from mechanical energy, being developed by the intermittent flow of heat in the normal direction from a source, where it is generated or applied, In each, a substantially constant volume of gas is alternately heated and cooled, thereby alternately raising and lowering its pressure. In the case of a compressor, these fluctuations in pressure are utilized to effect the transfer of gas between two regions of different pressure by admitting gas to the system from a region of low pressure when the pressure in the system is low, and ejecting gas from the system to a region of 35 high pressure when the pressure is high. In the case of a thermal pump, the fluctuations in pressure are utilized to effect corresponding fluctuations in pressure in another but communicating body of gas from which heat is ejected to a region of high thermal potential when the pressure is raised and which is caused to absorb heat from a region of low thermal potential when the pressure is lowered.

In each of the several forms of apparatus described in the prior applications above referred to, the alternate heating and cooling of the gas is effected by moving or transferring it between two relatively hot and cold regions in a cylinder n by means of a reciprocating member termed a displacer. Also, in the case of the thermal pump, the transfer of the second body of gas between the heat ejection and heat absorption regions is effected by a similar displacer. Such a 55 displacer has the additional function of providing,

in the cylinder, chambers of variable volume within which the gas meets walls of a substantially uniform temperature not greatly different at any time from that of the contained gas itself. In some instances, particularly in large installations where the ratio of volume to surface area is large, this second function can be economically dispensed with without substantial loss of efliciency, and other advantages thereby secured. In accordance with the present invention, the displacers of the prior applications are replaced by other gas moving means, for example, a continuously operating rotary blower with suitable provision for reversing the direction of circulation at the proper times. This has the advantage that the gas impelling means may be small, since it acts upon relatively small portions of the gas in sequence instead of acting upon substantially the entire body of gas affected at once. Also, instead of merely transferring the gas to the several regions (i. e., the heated region, the cooled region, the heat ejection region, and the heat absorption or refrigerated region), it is caused to flow through said regions to suitable storage spaces. Consequently, the heated region may be small, and the heat transfer to and from the other regions can be more effectually accomplished. Moreover, since, in the case of the thermal pump and that of the multi-stage compressor, only one movement of the gas need take place at one time, one blower, continuously operated, with suitable valves and connections, may be made to provide for all needed gas motions, although in both of these cases it is sometimes desirable to use separate blowers in order to more readily use different volumes of the separate storage spaces. The driving motor for such a blower may be located within the gas space, so that the apparatus may be hermetically sealed.

The foregoing and other objects and advantages of the invention will best be understood from the following description of the construction, arrangement and operation of certain forms of apparatus, illustrated in the accompanying drawings, in which it may be embodied and by which it may be practiced, these, however, having been chosen for purposes of exemplification merely, it being obvious that the invention, as defined by the claimshereunto appended, may be otherwise embodied and practiced without departure from its spirit and scope.

In said drawings:

Fig. 1 is a vertical sectional view, largely diagrammatic, of a thermal pump embodying the invention.

Figs. 2 and 3 are sections taken substantially.

on the lines 2--2 and 3-3, respectively, Fig. 1.

Fig. 4 is an enlarged section taken substantially on the line 4-4, Fig. 1.

Figs. 5 and 6 are sections taken substantially on the lines 5-5 and 6-6, Fig. 4.

Fig. 7 is a view similar to Fig. 1 showing an alternative arrangement.

Fig. 8 is a simplified diagrammatic view of a single unit, illustrating the principles of the invention as applied to a compressor.

Figs. 9 and 10 are longitudinal and transverse sections, respectively of an alternative form of regenerator.

Fig. 11 is a plan view of the heater shown in Fig. 1.

Referring first to Fig. 8, there is shown thereinan apparatus which comprises a cylinder or,

chamber I5 connected at its upper and lower ends, respectively, through pipes or conduits II and I1, with the upper and lower ends of a regenerator ll, thereby constituting a closed circuit or system containing a substantially constant volume of gas the major portion of which is enclosed in said chamber IS. The portion of the conduit l8 adjacent the cylinder I5 is arranged in the form of a coil located within a water jacket l9, whereby gas entering said cylinder through said conduit is cooled. The cylinder l5, regenerator i8, and water jacket l8 are preferably enclosed in an insulating jacket comprising an outer casing I l filled with suitable insulating material, such as lampblack. The conduit l! is locally heated, as by a suitable burner 2|. The regenerator i8 comprises a plurality of loosely intertwined tubes I8m each embedded in the insulating Jacket and all connected to common headers ilu, said tubes being composed of suitable material, such as stainless steel, capable of receiving and giving up heat rapidly but of low thermal conductivity, thereby providing a thermal gradient along the length of the regenerator, without serious loss due to heat conduction between the ends thereof. Alternatively, and as shown in Figs. 9 and 10, the regenerator may, in some cases, comprise a simple bundle of straight parallel tubes l8: of suitable material connected to common headers i811. Located at some point in the circuit or system, for example in the conduit I8, is a blower 23 for maintaining a substantially continuous circulation of gas therein, means being provided for periodically reversing the direction of flow. This may be accomplished by employing a rgtary blower with means for periodically reversing its direction of rotation or (in the case of aian blower) the angle of its blades, or by employing such a blower together with a suitable reversing valve, as hereinafter more fully explained. Also communicating with the system at suitable points are inlet and outlet passages 24 and 25 controlled respectively by inlet and outlet valves 26 and 21. As shown, these passages communicate with the conduit I! through a branch 28. The outlet passage 28 communicates with a region of relatively high pressure, such as a high pressure reservoir 29, and the inlet passage 24 with a similar low pressure reservoir or with the atmosphere or other region of relatively low pressure, depending upon the use to which the apparatus is to be put. Within the cylinder i5 is a separator 30 whose function it is to prevent relatively hot and cold gases from mixing, but which may, in some instances, be dispensed with, particularly if the cylinder be inverted to locate the cooled conduit at the bottom and the heated conduit at the top. The separator consists of a very light metal or insulating member slidably mounted by means of a sleeve 3i upon a central guide rod or tube 32 and having a smallclearance between its peripheral edge and the wall of the cylinder. The bearing of the sleeve ll upon the tube 32 is suitably lubricated as by a graphite lining. The ends of the cylinder II are preferably provided with recesses I51: to receive the ends of the sleeve 3| when the separator is in its extreme position and thereby reduce waste space. Said separator is preferably formed with double walls with a small gas space between and perforated at 30.1: to equalize internal and external pressures and prevent collapse. Due to its very light weight, it is readily moved or blown upwardly by the gas when the latter enters the bottom of the cylinder through the conduit i1 and downwardly when gas enters the top of the cylinder through the conduit It. If desired, a light spring s may be provided for the separator to contact with as it approaches the end of its downward movement and thus provide a slight impulse tending to keep it in correct mean position.

The cycle of operations of this unit is as follows: Starting with the separator 30 at the bottom of the chamber l5, as shown, and with both valves 2' and 2! closed, the blower 23 is operated to circulate the gas in the system in a clockwise direction, drawing cool gas from the upper end of the chamber through the conduit I6 and passing it downwardly through the regenerator it, where it absorbs a certain amount of heat, thence through the conduit I I. where it is further heated by the burner 2i, and finally into the lower end of the chamber, forcing the separator 30 upwardly. The chamber is thereby gradually filled with heated gas, so that the average temperature of the gas contained in said chamber gradually rises, and, since the volume of the entire system, and consequently of the total body of gas therein, is fixed or'constant, the pressure of said gas rises. At a definite point in the course of the circulation of the gas in this direction, the pressure equals or slightly exceeds the pressure in the reservoir 20. The outlet valve 21 then opens, and, as the circulation of the gas in the clockwise direction continues, the pressure remains nearly,

constant, except as the reservoir pressure increases slightly, and gas is forced through the outlet passage 25 into the reservoir. When the chamber has been substantially completely filled with heated gas, the direction of circulation is reversed, drawing gas from the lower end of the chamber through the conduit i] and passing it upwardly through the regenerator l8, when it gives up the greater part of its heat, and thence through the conduit it, where it is further cooled, and into the upper end of the chamber, the separator 2| moving downwardly. The chamber is Y thereby gradually filled with cool gas which causes a decrease in the pressure in the system. With the initial drop in pressure to an amount equal to or slightly less than that in the reservoir, the outlet valve 2'! closes; and when it is further reduced to an amount equal to or slightly less than that of the region with which the inlet passage 24 communicates, the inlet valve 26 opens. Therealter the pressure remains substantially constant due to the inflow 01' gas through said inlet passage and valve. These operations are repeated, the direction of circulation being periodically reversed, and the chamber is being filled with heated and cooled gas alternately, thereby, since able resistance.

pressure thereof, and resulting in the transfer of gas from a region of low pressure through the inlet valve to a region of high pressure through the outlet valve 21.

From the foregoing it will be seen that the compression or transfer "of the gas is effected primarily and directly by heat ener y. as distinguished from; and without the interposition of, mechanical energy or power. Although the apparatus includes certain mechanically operated moving parts, namely, the blower and the reversing valve, when the latter is used, these parts are merely for the control of the thermal Since the system comprises a closed circuit, the pressures at the inlet and outlet sides, respectively, of the blower are substantially balanced, so that the gas imposes no considerable resistance to the operation of the latter but flows substantially freely about the circuit under its impulse. Consequently, the ony force required to operate these controlling parts is that necessary to move the very light separator and to overcome gas friction and such mechanical friction as may develop in the parts themselves, all of which are relatively small.

The general principles utilized in the apparatus above described for the purp'se of transferring gas from one region to another of higher pressure, that is to say, against the direction of normal gas flow, can also be utilized for the purpose of transferring heat from one region to another of higher thermal potential, that is to say,

against the direction of normal heat flow. An

apparatus for effecting the latter result, and Cesigned for refrigerating purposes, is shown in Fig. 1. Said apparatus comprises two units A and B which, for convenience, may be termed the power or compressor unit and the refrigerator unit, respectively. The unit A comprises a cylinder l5a, preferably of stainless steel, and a regenerator "a; corresponding, respectively, to the cylinder l5 and regenerator I! of the apparatus above described and connected at their upper ends by a conduit l'la. In this construction, however, the regenerator l8a comprises a cylinder containing spaced, perforated, aluminum or copper disks 22. the perforations in adjacent disks being staggered, and the space not filed by the disks being relatively small. The unit B comprises a similar cylinder or chamber |5b and regenerator l8b connected at their upper ends by a heat absorption or refrigerating coil 33, preferably formed from a flattened tube. The lower ends of the regenerators l8a and Hlbprespectively, are connected by conduits 34a an 341) with a combined blower and valve casing 35, as hereinafter further described. The'conduit I la and the upper ends of the cylinder [5a and regenerator I811 are preferably enclosed by an insulating jacket comprisingan outer casing 36 sealed at its lower end to the cylinder and regenerator, the intervening space being filled with a suitable insulating material, such as lampblack.

Communicating with the lower end of the cylinder i5a are the upper ends of a plurality of curved, radially disposed heat exchange pipes 31a (see also Fig. 3) soldered to similarly disposed cooling fins 38a and communicating at their lower ends with an annular header 39a which, in turn, communicates, through a conduit 43a including an intermediate regenerator the cylinders.

I similar to the regenerators Ma and I lb, with the casing 35. Similarly, the lower end of the cylinder l5b communicates, through heat exchange pipes 31b soldered to cooling fins 33b, with an annular header 391) which, in turn, communicates, through a conduit 40!), with the casing 35. The temperature range between the several regions of the unit A is greater than that between the several regions of the unit B, so that it is permissible to employ a higher temperature, as compared to the air temperature, in the cooled region of the unit A, constituted by the heat exchange pipe 31a, than ispermissible in the heat ejection region of theunit B, constituted by the heat exchange pipes 31b. The cooling fins 38a may therefore be smaller than the cooling fins 38b. In the operation of the ap-' paratus, there is a certain amount of flow back and forth between the units A and B, due to fluctuations in pressure as hereinafter explained, and, in the course of this flow, the gas gives up a portion of its heat to the intermediate regenerator 'I in passing therethrdugh toward the right in Fig. 1, and absorbs heat therefrom in passing therethrough in the opposite direction.

Within the cylinders |5a and l5b in the construction shown, are separators 30a and 30b similar to the separator 30 and like it having sleeves 3| a and 3") guided on central guide rods or tubes 32a and 32b.

Located in the upper and lower ends of the cylinders, adjacent their points of communicat on with the pipes or conduits I'm, 33, 31a and 311), respectively, are honeycomb baffles 4la, 4| b, 42a and 42b for producing parallel or lamellar flow and preventing turbulence. These comprise (see also Fig. 2) circular grids or plates of thick sheet metal of sizes corresponding to the cross sections of the cylinders, having central openings to receive the sleeves 3m and 3H), and perforated to form parallel holes of angular cross section to cause the gas to flow parallel to the axes of the cylinders and at substantially uniform velocities across their cross sections, the metal portions separating the perforations being thin to offer as little resistance as possible to the flow of gas while permitting the grids to perform their intended function. This effect may be further enhanced, at the ends of the cylinders which communicate with the conduit I10. and refrigerating coil 33, by the use of additional baflle plates 43a. and 43b which act to distribute.

the inflowing gases across the cross section of Either the honeycomb bafiies or the separators may be omitted, although the use of both is preferred. If the separator 30b be omitted, the refrigerator unit B should be inverted to locate the heat exchange pipe 31b and cooling fins 381) at the top and the refrigerating coils 33 at the bottom.

Located at the upper end of the cylinder l5a, preferably between the baffles Ma and 43a, is an electric heater 44 (see also Fig. 11) comprisr ng a fiat ribbon of a suitable heater alloy arranged in the form of a spiral, supported by a transverse rod 44;: having porcelain spacers 441 between the convolutions of the spiral, and connected with lead wires 45 which, suitably insulated as by a porcelain tube, pass downwardly through the guide tube 32a and out through a suitably sealed outlet 46 in the lower end of the cylinder. This spiral is so shaped as to assist the baiile Na in producing parallel fiow, and may even replace the latter for this purpose.

Referring to Figs. 4, 5 and 6, the casing 35 a sealed outlet comprises three sections 41, l8 and .9 and is totally enclosed and may be hermetically sealed by soldering the joints between the sections after asscmbly. The section 41 encloses an electric motor 53 the lead wires to which are brought out at The section 49 encloses a pump or blower which, as shown, is of the ordinary gear pump type comprising two gears 52 and 53 one of which may be of steel and the other of impregnated fibrous material such as is commonly used in gears to reduce noise. The gear 52 is fast on the armature shaft 54 of the motor 50, and the casing section 49 is provided with suitably located outlet and inlet ports 55 and 55. The section 49 encloses a circular valve chamber 51 having about its circumference four equally spaced ports with which the conduits 34a, 34b, 49a and 49b communicate, and in which is located a rotary valve element 59 so shaped, as shown in Fig. 5, as to divide the chamber 51 into two spaces or regions 59 and 69. The wall 6| of the casing section 48 adjacent the section 49 is formed with a recess or gear space 62 in which is located gearing for slowly rotating the valve element 58. Said gearing comprises a pinion 53 fast on the shaft 64 of the pump gear 53 which meshes with a gear 65 having a shaft or trunnion 96 journalled in the wall SI and also having associated therewith a coaxial pinion 61 1 which meshes with a gear 59 having a hollow shaft or trunnion 69 likewise journalled in the wall 6 I. The valve element 58 is riveted or otherwise secured to the face of the gear 69 which is.

formed with a port Ill communicating with the valve space or region 69 and with an annular recess 1| formed in the adjacent face of the wall 5i and which, in turn, communicates with the inlet port 56. The port Ill and recess II are so located that they do not register or communicate with the portion of the gear space 52 containing cessively connected with the pump outlet, the

others being connected with each other and with the pump inlet, and the shape of the valve element 58 being such that it begins to open communlca ion from the space 59 to one of said conduits just as it begins to close such communication to the previous. conduit. Consequently, as the valve element 58 is rotated in a clockwise direction, as indicated by the arrow on Fig. 5, gas

will be blown in sequence, and in the order named, into the top of the cylinder l5a, into the top of the cylinder l5b, into the bottom of the cylinder l5a, and into the bottom of the cylinder l5b. The eifect of this cycle of operations is as follows:

Starting with the separators 30a and 30b in the upper ends of their respective cylinders, as shown in Fig. 1, and with the valve element 59 in the positon to connect the conduit 34a with the valve space 59 and blower outlet 55, relatively cool gas is drawn from the lower end of the cylinder l5a (which at this time is in communication through the conduit 40a with the valve space 60 and blower inlet 55) and blown into the upper end of said cylinder, the separator 30:; moving downwardly. During this operation, the gas passes upwardly through the regenerator I 9a, where it absorbs heat, and thence through the conduit I'la into the upper end of the cylinder where it is further heated by the heating coil 44. The cylinder a is thereby gradually filled with heated gas, so that the average temperature of the gas contained in said cylinder rises. Since the two units are at this time interconnected through the conduits 40a, 34b and 40b and valve space 60, and since the system is a closed one and the total volume of gas contained therein constant, the gas pressure in the whole apparatus, including the unit B, rises. The valve 58 then moves into the position to connect the conduit 34b with the valve space 59 and blower outlet 55, and the conduits 34a, 40a and 49b with the valve space 69 and blower inlet 56. Gas is thereupon drawn from. the lower end of the cylinder l5b through the heat exchange pipes 31b, where the greater portion of its heat is ejected by the cooling fins 38b, and passed upwardly through the regenerator l8b, where it gives up additional heat, and through the refrigerating coils 33 into the upper end of the cylinder l5b, the separator 30b moving downwardly, so that said cylinder is g.adually filled with relatively cool gas. The valve 58 then moves into the position to connect the conduit 40a with the valve space 59 and blower outlet 55 and the conduits 34a, 94b and 49?) with the valve space 60 and blower inlet 55. Gas is thereupon drawn from the upper end of the cylinder 15a through the conduit Fla and downwardly through the regenerator I811, where it gives up a portion .of its heat, and is passed through the heat exchange pipes 31a, where it is further cooled by the fins 38a, the separator 30a being forced upwardly. The cylinder 15a is therefore gradually filled with cold gas, and the average temperature of the gas in said cylinder falls, so that the pressure in the system as a whole falls, and the gas in the cylinder l5b is expanded and further cooled or refrigerated. The valve 59 then moves into the position to connect the conduit 40b with the valve space 59 and blower outlet 55 and the conduits 34a, 34b and 40a with the valve space 60 and blower inlet 56. The refrigerated gas in the cylinder l5b is thereupon drawn from the upper end of said cylinder through the refiigerating coils 33, which are thereby refrigerated and enabled to absorb heat from the region to be cooled, and downwardly through the regenerator 182), where it absorbs the heat given up during its upward passage, and is passed through the heat exchange pipes 31b into the lower end of the cylinder l5b, the separator 39b moving upwardly. Consequently the coils 33, and the region in which they are located, will be cooled or refrigerated. The valve 58 then moves into the position to connect the conduit 34a with the valve space 59, thereby completing the cycle.

The blower and reversing valve unit 23, above referred to in connection with the apparatus shown in Fig. 8, may obviously be substantially like that shown in Figs. 4, 5 and 6, except that the valve chamber 51 would be provided with two ports communicating respectively with the portions of the conduit l6 at opposite sides of the unit, and the valve element 58 so modified as to place these ports alternately in communication with the blower inlet and outlet, respectively. When a continuously operating positive blower, such as a gear blower, is used, extra ports should also be provided to permit the gas to be freely circulated about a short path or by-pass during the intervals when the blower is not circulating gas through the system.

In each of the several forms of apparatus herein described, the heat exchange regions, such as the. refrigerating coils 33, heat exchange pipes 31a, 31b, regenerators I8a, Ilb, etc., are so designed with reference to the velocities employed as to give a Reynolds number above that representing the critical point of turbulence, so that the flow of gas through these regions is turbulent. By reason of this, as well as of the more or less tortuous forms of the paths traversed,'the gas is brought into close thermal relationship with the several heat exchange elements, 1. e., the walls of the several tubes or pipes, the regenerator elements, etc., and the rapid and efiicient extraction and absorption of heat at the desired points thereby promoted. On the other hand, in the storage spaces, i. e., the cylinders Ila and lib,

containing a fixed volume of gas and including a region provided with means for establishing a substantially quiescent film of gas on the walls the fiow is slow and parallel or lamellar: due to the large cross section of the cylinders, the honeycomb bailles a, lib, 42a, 4212, etc. Consequently, the amount of gas which is brought into thermal relationship with the walls of the cylinders is very small in proportion to the total volume of gas therein, there is no considerable heat interchange, and the gas at any time in a cylinder is thermally isolated therein and retains substantially the temperature at which it entered except for differences resulting from pressure changes. This result is enhanced by the fact that, due to the lamellar flow, and also, in part, to the action of the separators, there tends to form on the walls of the cylinders a more or less permanent, quiescent film of gas which acts as an excellent thermal barrier and is fully as effective as a wall of solid heat-insulating material. The great difference between the heat transfer resulting from the turbulent flow through small, tortuous, or subdivided passages in the heat exchange regions, and that resulting from the slow lamellar flow through the large cross section storage spaces, renders the apparatus described highly practical and eificient and makes possible the adoption of the blower circulating means described with the advantages above pointed out.

In Fig. 'l is shown, in simplified and diagrammatic form, a more compact arrangement, and

one better suited to actual installation in certain situations, of apparatus otherwise substantially similar, as to its general organization and mode of operation, to the apparatus shown in Fig. 1. As shown in Fig. '7, the power and refrigerator units A and B, respectively, are coaxially arranged within a cylindrical outer casing or housing 15, the power unit being at the top, and both units being inverted with respect to those shown in Fig. 1, so that the heated end of the unit A and the refrigerated end of the unit B are located at the bottom of the respective units. The motor I", blower I48, valve I49, and intermediate regenerator I are located between the units, and the refrigerator unit B is enclosed in an insulating jacket I361) similar to the jacket iii of the power unit A. The remaining parts of the apparatus shown in Fig. 'l are indicated in said figure by the same reference numerals as the corresponding parts in Fig. 1, but with the numeral 1 prefixed in each case, and will, it is thought, be clearly understood without further description.

possible to employ pressures substantially higher than atmospheric and thereby obtain a large output with a given volume, and it is also desirable to use as a working medium a monatomic gas, such as argon or helium, of low molecular specific heat, all as more fully discussed in the prior applications above referred to.

We claim:

1. Thermal apparatus comprising a closed container having a plurality of relatively small volume regions at diverse temperatures and storage regions of relatively large volume, circulating means for transferring portions of the enclosed gas along paths within the apparatus in a repeated sequence, and means for establishing a turbulent flow of the circulating gas in the small regions and lamellar flow thereof in the large regions, whereby heat is caused to be transferred among the several small regions.

2. A thermal apparatus comprising means for thereof and thereby thermally insulating the same, means for circulating said gas about said containing means in such a manner as to cause portions thereof to intermittently enter and leave said insulated region, and means for alternately heating and cooling gas entering or leaving said region.

3. In an apparatus of the character described, a gas containing system of substantially constant volume and including a chamber, a regenerator and conduits respectively connecting the opposite ends of said regenerator with said chamber, means for heating gas entering said chamber through one of said conduits, means for cooling gas entering said chamber through the other of said conduits, and gas circulating means for producing a substantially non-turbulent flow of gas into opposite ends of said chamber in alternation by circulating the gas alternately in opposite directions through said system, said gas circulating means comprising a continuously running blower and a distributing valve.

4. Thermal apparatus comprising a closed container having a plurality of relatively small volume regions at diverse temperatures and storage regions of relatively large volume, circulating means for transferring portions of the enclosed gas along paths within the apparatus in a repeated sequence, and means for establishing turbulent flow of the circulating gas in the small regions and lamellar flow thereof in the large regions, whereby heat is caused to be transferred for heating gas entering or leaving said chamber through one of said conduits, means for cooling gas entering or leaving said chamber through the other of said conduits, a second gas chamber, heat exchange conduits communicating with said second chamber and with said first named conduits, a blower, and a valve controlling communication of the blower inlet and outlet with said conduits for causing gas to flow into said first named chamber alternately through said two first named conduits and in alternating sequence for causing gas to fiow through said second chamber and heat exchange conduits alternately in opposite directions.

6. A thermal pump comprising a gas chamber, a conduit communicating therewith, means forheating gas entering or leaving said chamber through said conduit, a second conduit communicating with said chamber, means for cooling gas entering or leaving said chamber-through said second conduit, a second gas chamber, heat absorption and heat ejection conduits communicating with said second chamber, a blower, a valve casing having ports communicating with the several conduits, and a rotary valve in said casing adapted, when rotated, to place said first named conduit, said heat absorption conduit, said secondconduit, and said heat ejection conduit, in the order named, in communication with the blower outlet and the remaining conduits in com-' munication with the blower inlet.

'7. A thermal pump comprising two closed gas containers one of which includes a heated region and a cooled region and the other of which includes a heat absorption region and a heat ejection region, a single gas-displacing means for acting in succession upon volumes of gas that are small in relation to the volumes of gas in the containers, each container including a chamber and conduits for providing communication be-l tween opposite ends of said chambers and said gas displacing means, and valve means controlling communication between the several conduits and said gas-displacing means for efiecting a circulation of said gas in predetermined sequence through the several regions of both containers and for establishing continuous communication between the two containers.

8. A thermal pump comprising a closed system including two intercommunicating gas containers one of which includes a heated region and a cooled region and the other of which includes a heat absorption region and a heat ejection region, a blower for circulating gas about said system, and

alternately in opposite directions and in a predetermined sequence through the several regions of both containers.

9. A thermal pump as claimed in claim 8,

wherein said gas-directing means is a rotary valve mechanically driven by said blower.

10. A thermal pump as claimed in claim 8, wherein said gas-directing means is a rotary valve geared to said blowe'r, said valve and blower having a common casing.

11. Thermal apparatus of the type including a closed container, a regenerator, circulating means for alternately passing gas from end to end of said container through said regenerator, and means for mechanically separating the bodies of gas of different temperature that occupy different ends of said container, characterized by the fact that said separating means comprises a lightweight separator and means guiding said separator for movement from end to end of said container, said separator being displaceable by the unbalanced pressures established at opposite ends of said container by said circulating means.

12. Thermal apparatus comprising a container of fixed volume, a regenerator, circulating means for alternately passing gas from end to end of said 'container through said regenerator, and

means at opposite ends of said container for establishing a lamellar flow of gas in the same during movement of the gas by said circulating means.

13. In the operation of a constant volume thermal system of the type in which gas is alternately transferred from one end of a thermally insulated container to the other end through a regenerator,

the method which comprises establishing a turbulent flow of gas through the regenerator to promote heat transfer, and establishing a lamellar flow of gas in the container to minimize a heat transfer.

VANNEVAR BUSH. EDWIN L. ROSE.

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