US2475764A - Caloric piston engine comprising heat exchange devices - Google Patents

Description

July 12, 1949. G. J. H. VERMEER 2,475,764

. CALORIC PISTON ENGINE COMPRISING HEAT EXCHANGE DEVICES Filed April 12, 1946 s Sheets-Sheet 1 22 FIGJ FIG. 2

GERARD J. H. VERMEER iNVENTOR MMM7 AGENT G. J. H. VERMEER CALORIC PISTON ENGINE COMPRISING July 12, 1949.

HEAT EXCHANGE DEVICES 5 Sheets-Sheet 2 Filed April 12, 1946 FIG. 6

FIG. 5

GERARD J. HNERMEER AGENT y 1949- G. J. H. VERMEER 2,475,764

CALORIC PISTON ENGINE COMPRISING v HEAT EXCHANGE DEVICES Filed April 12, 1946 3 Sheets-Sheet 3 Ill k JIHI 1 1 11,111 11 r1111 11,, I I 1 GERARD J H VERMEER INVENTOR.

A GENT Patented July 12, 194 v CALORIC PISTON ENGINE COMPRISING HEAT EXCHANGE DEVICES Gerard Jan Huber tus Vermeer, Eindhoven, Netherlands, assignor, b

Hartford National y mesne assignments, to Bank and Trust Company,

Hartford, Conn., as trustee Application April 12, 1946, Serial No. 661,472 In the Netherlands December 6, 1945 7 Claims.

This invention relates to caloric piston machines (hot-gas engine refrigerating apparatus operating on the reverse hot-gas engine principle) in which the working chamber is surrounded by an annular space which compnses, owing to the presence of one or a plurality of walls, a number of spaces both for the working medium and for the medium which is in heatexchanging contact with the working medium, which spaces are located in such manner that as viewed in a section normal to the axis of the working space through the annular chamber, there are on an annular strip of this section spaces for the working medium as well as for the medium which is in heat-exchanging contact with the former. In order to ensure a high output of such a machine, it is desirable that the heat-exchanging contact should be optimum. n the one hand, it is desirable that the media should experience a minimum resistance in the machine on passing through the spaces intended for them. This can be ensured by giving the paths along which the media move through the ducts, a comparatively short length. Now, applicant has found that these requirements can be fulfilled by using the present invention.

The caloric piston machine, according to the invention, has the feature that the partitions between the two media are provided, on one or on either side, with projecting parts such as ribs, fins or the like, so that on at least one of the sides of these partitions the medium on that side is compelled to flow, in a plurality of parallel paths, along the partitions in one or more directions at an angle with the longitudinal direction of the partitions.

By the subdivision of one or of the two media into a plurality of parallel paths of flow it is ensured that this subdivided medium is in a highly satisfactory heat-exchanging contact with the partition concerned. If, in addition, these flows are guided along the partitions by the location of the projecting parts thereof in such a manner as to make an angle with the longitudinal direction of the partitions, it is, moreover, ensured that the paths along which these flows pass along the partitions in question are very short with the result that the resistance experienced b the medium concerned is low.

In one form of construction of the piston machine, according to the invention, the ducts for the medium which is in heat-exchanging contact with the working medium are formed by a plurality of tubes protruding into the annular space and externally provided with projecting parts.

2 It is advisable that these tubes, at least through the greater part of their length, should be slightly inclined with respect to the axis of the working space and this in such manner that the ends of the tubes in the proximity of the machine lid are remotest from the axis of the working space. In connection with the average direction of flow of the medium out of the engine space along the heat-exchanger to the remaining part of the engine and conversely, it is thus ensured that the paths along which the working medium is in contact with the walls separating this medium from the medium with which the former is in heat-exchanging contact, may have a short length. In addition, the heat-exchanging surface available can be used more effectively than in the well-known heat-exchanger.

In a further form of construction of the caloric piston machine according to the invention the spaces for the working medium and for the medium which is in heat-exchanging contact with the former are separated by a screen which is folded zigzag and arranged in the annular space.

The projecting parts on the partitions between the two media may be obtained by locally embossing the material of the wall which ensures a light construction. As an alternative, the projecting parts may be made in a different manner. for example by milling grooves in the relative portions of the wall, in which event the wall portions that have not been milled away form the projecting parts.

In a further form of construction of the piston machine according to the invention the spaces for the medium which is in heat-exchanging contact with the working medium comprises supply pipes for a combustible'gas, which pipes end in these spaces with a plurality of apertures, the projecting parts being provided on the sides of the circumscribing walls of these spaces which are facing these spaces, in such a manner as to form on these walls ducts for the flames leaving the gas outlets.

In order that the invention may be clearly understood and readily carried into eifect, it will now be explained more fully by reference to the accompanying drawings. a

Figure 1 is a diagrammatic sectional view of the head of a hot-gas engine.

Figure 2 is a longitudinal section of the head of a hot-gas engine in which a modified structure of the heat exchanger is shown.

Figure 3 is a transverse section of the modified heat exchanger along the line III-III in Figure 2.

Figure 4 is a longitudinal section of the modified heat exchanger along the line .IV--IV in heat exchanger shown in hot-gas engine in which a third form of the heat exchanger is shown.

is a horizontal cross sectional view in the drawing, may be slightly inclined relatively to this axis. The latte form of construction thereby avoids too large a clearance space in the apparatus, and has the further advantage that the ducts between the ribs l4 can, in general, be given a smaller length.

In a further form of construction or the machine according to the invention, shown in Figures 2, 3 and 4 of which Figure 2 shows a longitudinal section of the head of a. hot-gas engine, Figure 3 is a sectional view taken along the line IIIIII of Figure 2, and Figure 4 is a sectional the tubular heat exchanger shown in Figures 1 and '7.

Figure 9 is a horizontal cross sectional view of an alternate construction of the tubular heat exchanger shown in Figure 1.

Figm-e 1 is a diagrammatic sectional view of the head of a hot-gas engine as noted hereinabove. In it the displacer I is movable in a cylinder 2. The working space in the cylinder' 2 is surrounded by an annular space 3 which com- .municates, through an annular passage 4', with the working space inside the cylinder 2. At the top of the head the lid 5 has introduced through it a plurality of tubular heating elements 6 which form, so-to-say, re-entrant parts in the space 3. For simplicity's sake the figure only shows two of these tubes 6; Under the tubes 6 is arranged a regenerator 1. When .the displacer I moves upwards the medium enclosed in the working space 2 is driven upwards and enters through the passage 4 into the annular space 3,

the medium flowing between the tubes 6. The

latter are flattened and are closed at their bottom ends 8 and open at their top ends 9. In the longitudinal direction they are divided into two parts by partitions i0 (shown in Figure 1 by dotted lines in horizontal cross section in Figure 7) ,which nearly extend to the bottom 8 of the tubes.

This is shown more clearly in the longitudinal sectional view of Figure 8. In this manner a U- shaped duct is formed in the re-entrant parts.

' designates the lid of the engine.

view taken along the line IV-IV of Figure 2 as noted hereinabove, reference numeral 2| desi nates the cylinder lining in which a displacer (not shown) is movable. Reference numeral 22 Outside the cylinder lining 2| is provided an annular chamber 4|, which is externally circumscribed by a wall 33. This chamber comprises spaces or ducts 42 for the medium which is active in the engine, and spaces or ducts 43 for the medium which is in heat-exchanging contact with the former. These ducts are separated from one another by the zigza screen 24. This screen has, at the top and at the bottom. a folded rim 25 which is secured, by means of soldered or welded joints to the adjacent parts ofthe engine. The top ends of the ducts 42 intended for the working medium are closed by the elongated projecting parts 4'4 of the lid 22 of the engine and the bottom ends of the ducts for the gases which are in heat-exchanging contact with the working medium, for example, the flue gases of a burner are closed by means of the elongated projecting parts of a plate 23. The top ends of the ducts .43 are open. Into these the flue gases of the Fig. 9 is a horizontal cross section of an alternate construction of the tube 6 wherein a rectangularly shaped heating element 6' is shown instead of the circular tube 6. In the rectangularly shaped heating element 6, i0 is the dividing partition and I4 designates the ribs. Adjacent the top of the tubes 6 is an annular parti- F tion H, by means of which the inlet apertures l2 of the tubes 6 are separated from their outlet apertures l3. On top of the head of the engine, inside the annular partition II, is arranged a burner whose exhaust gases can thus only flow through the U-shaped ducts in the tubes 6. These gases follow the path designated by arrows. The working medium flowing between the tubes 6 is consequently heated by the walls of these tubes. Owing to the fact that a great number of ribs H are provided on the outside of the reentrant parts, the latter have a great number of ducts formed on them by which the working medium is subdivided to a greater extent and by which all these parallel-flows of the working medium come into intimate, heat-exchanging contact with the walls of the tubes 6. It can be seen from Figure 1 that by the inclined position of the ribs I4 with respect to the longitudinal axis of the walls of tubes 6 the ducts existing between these ribs are short with the result that the resistance experienced by the working medium is low. The longitudinal axis of the re-entrant parts 6 may be positioned in parallel with the axis XX of the working space, or. as is the case and the annular'partition 32. The combustion gases traverse the spaces intended for them in the zigzag screen and leave at 34 from the heatexchanger. The path of the flue gases is designated by arrows P. The working medium, the course of which in the heat-exchanger is designated by arrows Q, flows past the top edge of the cylinder lining 2| into the spaces of the zigzag screen, which are open to the inside, traverses these spaces and leaves the heat-exchanger through the apertures between the projecting parts 23. Subsequently, this medium finds its way to the regenerator 21, which is enclosed between the outer wall of the engine and the wall 29. In order to reduce the clearance space in the engine, the space 30 in the engine is separated from the space for the working medium by means of the aforesaid wall 29 and the wall 28, which is provided with embossed parts 45. As can be. seen from the figures, the walls of the screen are furnished with ribs 26, which are preferably provided in them by pressing before the screen has been folded zigzag. As can more particularly be seen from Figure '2, these ribs form an angle of about 45 with the longitudinal direction (which extends parallel with the axis XX of the engine space) of the wall, which is formed in this case by the zigzag screen 24. It is thus ensured that the paths thus produced along the screen for the working medium in the engine have a direction somewhat corresponding to the shortest path of the working medium from the engine space to the regenerator and conversely. Short gas paths are thus ensured, which is of importance for a minimum resistance of the gas, whilst the ribs ensure a particular satisfactory heatexchanging contact between the two media.

Owing to .the fact that the ribs 26 have been obtained by pressing the material of the screen 24, in this form of construction the paths for the flue gases also have ribs. due to which the flue gases along the ribs follow paths which are substantially parallel to the paths for the working medium and which consequently form also an angle of 45 with the longitudinal direction of the parts of the zgzag wall 24. The spaces intended for the flue gases contain screens 3| of key-shaped sections which, on the one hand. prevent the walls of the zigzag screen from being bent outwards due to any difference of pressure which may exist between the spaces on either side of these walls while, on the other hand, the flue gases are thus compelled to flow along the ribs provided on the walls of the screen 24. The spaces inside the screens 3! are closed at their top by the partition 32. It can furthermore be seen from Figure 2 that the connecting lines DD and EE between the extreme points of the ribs 26 make an angle with the axis X--X of the working space. It is'thus ensured that the medium flowin from the working space to the regenerator or from the regenerator to the working space (arrows Q) and the combustion gases arrows P) are distributed somewhat evenly over the ducts between the ribs 26.

Figures 5 and 6 are partial longitudinal and cross sectional Views respectively of a third form of construction of the heat-exchanger in the engine according to the invention. In this case the working space 50 of the engine is surrounded by an annular space 5! which comprises ducts 53 for the working medium and ducts 54 for the medium which is in heat-exchanging contact with the former. In the ducts 56 are provided pipes 55, which contain a combustible gas. These pipes have outlets 56 through that part of their length which protrudes into the space 54. 'Besides, the partitions 51 between the spaces 53. which extend substantiall radially, are provided with ribs 58. When the heat-exchanger is operative and the gases at the outlets 56 are burnins We obtain, by suitably shaping the mouthpieces of the burners, the flames 59 which are shown in Figure 6. They transfer their heat to the ribs 58 on the walls 51, whereas the ribs provided on the other side of thewalls 5'! transfer this heat in their turn to the working medium in the engine space. Consequently, in this form of construction there are ribs on either side of the walls 51, which ribs make an angle with the longitudinal direction of the walls, which extends in parallel with the axis Y-Y of the working space.

What I claim is:

1. A caloric piston machine comprising first means defining a working chamber for the working medium used in the machine, second means defining an annular chamber surrounding a section of said working chamber, said Working chamber and said annular chamber being in gas communication with each other whereby the working medium may flow between said working chamber and said annular chamber, at least one heat exchanger element in said annular chamber, said heat exchanger element having a heat exchanging fluid inlet and a heat exchanging fluid outlet and comprising wall means for keeping the working medium separated from the heat exchanger fluid but in heat exchange relationship therewith through the body of said wall means, said heat exchanger element extending longitudinally in said annular chamber substanchamber, and said wall means of said heat exchanger element having a plurality of parallel projections thereon which are at an angle to the longitudinal axis of said heat exchanger element.

2. A caloric piston machine as claimed in claim 1. wherein the heat exchange element is in the form of a tube protruding into the annular chamber.

3. A caloric piston machine comprising first means defining a working chamber for the working medium used in the machine, second means defining an annular chamber surrounding a sec tion of said working chamber, said working chamber and said annular chamber being in gas communication with each other whereby the working medium may flow between said working chamber and said annular chamber, at least one heat exchanger element in said annular chamber, said heat exchanger element having a heat exchanging fluid inlet and a heat exchanging fluid outlet and comprising wall means for keeping the working medium separated from the heat exchanger fluid but in heat exchange relationship therewith through the body of said wall means, said wall means being in the form of a tube, said tube extending longitudinally in said annular chamber and slightly inclined in relation to the axis of said working chamber, and said tube having a plurality of parallel projections thereon which are at an angle to the longitudinal axis of said tube in said annular chamber, said angle being in a direction opposite the inclination of said tube.

4. A' caloric piston machine as claimed in claim 1, wherein the wall means comprises a zigzag screen.

5. A caloric piston machine as claimed in claim 1, wherein the parallel projections are ribs pressed from the wall means.

6. A caloric piston machine comprising first means defining a working chamber for the working medium used in the machine, second means defining an annular chamber surrounding a section of said working chamber, said working chamber and said annular chamber being in gas communication with each other whereby the working medium may flow between said working chamber and said annular chamber, at least one heat exchanger element in said annular chamber, said heat exchanger element having a heat exchanging fluid inlet and a heat exchanging fluid outlet and comprising wall means for keeping the working medium separated from the heat exchanger fluid but in heat exchange relationship therewith through the body of said wall means, said heat exchanger element extending longitudinally in said annular chamber substantially in the direction of the axis of said working chamber, and said wall means of said heat exchanger element having a plurality of parallel projections thereon which are at an angle to the longitudinal axis of said heat exchanger element, said wall means comprising a zigzag screen and having spacer elements in the spaces formed by said zigzag screen.

7. A caloric piston machine comprising first means defining a working chamber for the working medium used in the machine, second means deflning'an annular chamber surrounding a section of said working chamber, said working chamber and said annular chamber being in gas communication with each other whereby the working medium may flow between said working chamber and said annular chamber, at least one heat exchanger element in said annular chamber, said heat exchanger element having a heat exchanging fluid inlet and a heat exchanging fluid outlet and comprising wall means for keeping the working medium separated from the heat exchanger fluid but in heat exchange relationship a combustible gas projecting thereinto and ending therein with a plurality of apertures, the projections on the sides of said wall means which face said supply pipe being located in relation to said apertures so as to form ducts on said wall means for the flames coming out of said apertures.

GERARD JAN HUBERTUS VERMEER.

REFERENCES CITED Thefollowing references are of record in the file of this patent? UNITED STATES PATENTS Name Date Lundgaard Apr. 21, 1925 Number

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