US1912556A - Heating convector - Google Patents

Description

June 6, 1933. R. s. WENTWORTH HEATING CONVECTOR Filed Feb. 6, 1951 Patented June 6, 1933 UNITED STATES PATENT GFFEQE ROBERT S. WENTWORTH, OF IOI-INSTOWN, PENNSYLVANIA, ASSIGNOR T NATIONAL RADIATOR CORPORATION, OF JOHNSTOWN, PENNSYLVANIA, A CORPORATION OF DELAWARE HEATING GONVIECTORv Application filed February 6, 19.31. Serial No. 513,883.

This invention pertains to heating radiators and more particularly to radiators of the type commonly known as convectors.

The requirements of modern heating 1nstallations demand the use of radiators of smaller dimensions than the present standard type of radiation. Modern heating 1nstallations, however, favor the use of completely enclosed radiators contained within cabinets setting in the room, or in cablnets built into the wall structure, air entering the cabinets at the bottom, passing through the heating units, and emerging through an opening at the top of the cabinet above the radiator. Radiators adapted for use 1n enclosures of this kind are commonly referred to as convectors. The limited dimensions of the cabinet in which they are located require the radiators to be very compact and highly efficient. Specially constructed units hav-' ing horizontally extending copper tubes with radiating fins thereon have been largely used for this purpose because of the relatively large amount of heat which can be dissipated per pound of metal in the radiator.

Cast iron radiators as heretofore constructed for such use have met with less favor even though cast iron is cheaper metal and is more resistant to acid corrosion than copper, because of the relatively high amount of metal employed relatively to the amount'of heat dissipated.

The art of casting necessitates a very appreciable wall thickness in the radiator and if radiating fins are provided to give increased air heating surface, the number of fins and the spacing of the fins is very definitely limited by the practical problems of molding. If the fins are too closely spaced or they are made too thin, the pattern can not be successfully lifted from the sand, or the metal will not run freely into the mold cavities.

According to the present invention, there is provided a radiator specially adapted for cast metal construction wherein there is a considerably higher efliciency per pound of metal employed than has been obtainable in other types of cast metal convector radiators. It is also contemplated that the radiator made in accordance with the present invention shall be adaptable for use in cabinets of different depths with a high degree of efliciency in the different cabinets. The invention also contemplates a type of construction which enables the space within the cabinet to be utilized to the best possible advantage.

The invention may be readily understood by reference to the accompanying drawing in which Figure 1 represents an end view of a radiator embodying my invention, the outline of the cabinet being diagrammatically indicated around the radiator;

Figure 2 is a front elevation of the radiator assembly, and in this view also the di mensions of the inside of the cabinet or compartment for receiving the radiator are indicated;

Figure 3 is an end view showing the end section reversed, whereby the pipe connecion is at the top;

Figure 4 is a transverse section in the plane of line IVIV of Figure 3, Figure 4 however being on a larger scale;

Figure 5 is a curve showing the falling off in the rate of heat transfer from the surface of the radiator to the air over a distance of several inches of air travel; and

Figure 6 is an enlarged detail view of a portion of the barrel of a section showing the angular relation between the heat radiating tins and the longitudinal and transverse axes of the barrel.

As stated above, radiators used as convectors are housed in cabinets or recesses in the wall of a building. The bottom of the cabinet is usually flush with the floor line of the room in which the radiator is located, while the top of the cabinet is quite customarily flush with the window sill of the room. There is an opening at the bottom of the cabinet and another opening at or just below the top of the cabinet, while the front of the cabinet is completely closed between the opening at the I top and the opening at the bottom.

In Figures 1 and 2 A designates the inside of the cabinet having an opening B near the top and on opening C near the bottom. The front of the cabinet is closed as indicated by the wall D. Sometimes these cabinets are set in the room, in which case they are made of sheet metal, but the present tendency is to build them into the wall structure. The depth of tne cabinet is limited by the amount of floor space available in the room for the accommodation of the cabinet, in case the cabinet is set in front of the wall, and is limited by the thickness of the wall of the building where the cabinet is built directly into the wall. Furthermore, radiators are commonly placed under a window sill and the length of tile air openings or grille for the cabinet is usually restricted to the length of the window sill in order to secure an artistic eifect.

A standard type of radiator may be successfully employed in a cabinet of this kind. However, the air passing from the bottom of the cabinet toward the top is heated very considerably in the first few inches of travel where the diiierence in temperature between the air and the radiator is greatest. However, as the air becomes more highly heated its capacity for absorbing additional heat is reduced with the result that there is a fairly high efiiciency with a standard type of section in the lower part of the cabinet. The upper part of a standard radiator so enclosed, however, gives very little additional heat to the air in proportion to its bulk or volume, so that the total amount of heat delivered to the air per pound of metal is extremely low where such a standard section is employed.

On the other hand, the depth of the cabinet, i. e., the distance from the inside of the front wall D to the back wall, is usually so small that a cast metal radiator which was only a fe inches high would not have a sufiicient heat dissipating area unless the cabinet could be very long.

According to the present invention there is provided a radiator 2 within the cabinet A comprised of a plurality of intermediate sections 3 between end sections 4 and 5. The intermediate sections 3 are provided at the top with a header portion 6 and at the bottom with a header portion 7, these headers being connected by a substantially elliptical barrel 8. The headers are provided with nipple ports and the center line between the nipple ports coincides with the longitudinal axis of the section so that they are symmetrically arranged and difi'erent pairs of core bosses are not necessary in the casting of the sections.

The ba rel is set so that the longest axis of the ellipse extends from the front to the back of the cabinet. The wide side faces of the barrel are provided with transversely extending fins 9, these fins extending across the width of the barrel and being spaced as close together as good casting practice will permit or as the needs demand. If the fins are too close together dust is apt to accumulate on them, eventually clogging many of the air passages. Consequently, it is not desirable that the fins should be spaced too closely together. The fins, however, instead of going straight across the barrel, at an angle of 90 to the long axis of the barrel, are inclined at an angle with reference to the axis of the barrel as clearly shown in Figure 3.

It will be obvious that if the fins went straight across the barrel at 90 to the longitudinal axis there-cf, i. e., parallel with the transverse axis of the barrel, the would have a minimum length and the greatest number of fins could be used with the minimum spacing between the fins. The more the fins are inclined with respect to the transverse axis of the section, the fewer the number of fins that can be employed even though the spacing between the fins remains the same. It is desirable that there shall be as many fins as possible without crowditg them too much. Also, it is desirable that the fins be as short as possible. This is apparent from an inspection of the curve shown in Figure 6. The curve indicates the falling away of the amount of heat transferred to the air the longer it travels pastthe hot metal surface of the radiator. In the first four inches of travel past the hot surface of the metal the rate of heat transfer is above the standard rating, indicated as 100% on the curve, and beyond this it is below the standard of rating. A. 100% rating is the point at which a square foot of surface will condense one-quarter pound of steam per hour when the steam is at a temperature of 215 F. and the air in the room is This equals 240 B. t. us per square foot per hour. In order, therefore, to secure the highest efilciency per pound of metal employed, it is obviously desirable to have a short air travel and a lot of surface.

F or this reason there is, an advantage in having a large number of fins and having the fins relatively short. However, if the fins were parallel with the transverse axis of the section, or at 90 to the longitudinal axis, while they ould be of the shortest length, and the greatest number of them to be pr vided with the desired spacing between them, there would not be sufficient slope to the channels between the fins to induce a high velocity of air through these channels. Since the efficiency of the radiator is also dependent upon the velocity of the air which it will orculate, it is desirable that the fins should be set at an angle which will induce a free flow of air through these channels between the fins.

I have found that the best length of fins, space of fins and slope obtains where the fins are at an angle somewhere between 2? and el5 to the plane of the transverse axis of the section. This will be understood by reference to Figure 6 in which the line a'a2 indicates the longitudinal axis of the section and yy is a line representing the plane parallel with the transverse axis of the section. The fin 2-2 is at an angle to both the lines wcc and 3 y. The angle 2 ranges between 27 and a and more especially between 27 and 88. As a matter of practice, I prefer that the angle y2 shall be 33. This angle gives the greatest efficiency for the section over the widest range of adjustments for the angularity of the sec tion itself. In other words, in Figure l the section is inclined at what is ordinarily the minimum angle with respect to the vertical position, but in use the same section may be set at a much greater angle. Forming the fins at an angle of 33 with respect to the plane of the transverse axis of the section gives the best results over the range of angular adjustments to which the section might have to operate. The fins have merely been illustrated in the conventional way, but Figure G'discloses the angularity actually preferred.

The fins are uniformly spaced. They are parallel at all points, and are of uniform thickness throughout. The fins project a considerable distance out from each side of the barrel, but the overall width of the section from the tip of one fin to the tip of the next is slightly smaller than the overall width of the header portions 6 and 7.

The end sections 4 and 5 are substantially the same as the intermediate sections with the exception that one of the headers 6 or 7 is provided with an offset connector portion 10, the center of which is laterally offset with respect to the center of the header portions 6 and 7.

There are several advantages in the provision of the connector portion 10 in that this connector portion will always be spaced away from the back and front walls of the cabinet, enabling the inlet and outlet pipes to enter the bottom of the end sectionsyas shown in Figure 2, or it enables one or both of the end sections to be reversed and still the pipe connection will be between the front and back walls of the cabinet. Even though the sections are inclined to a. .considerably greater angle than that shown in Figure 1,

'the connections can still be conveniently made. Because of the factthat the connections can come into the bottom or into the top of the sections instead of into the ends, as is commonly the practice, it is possible to make the radiator substantially the full width of the cabinet. This is apparent from Figure 2 in which I have shown a radiator comprised of eight sections the overall length of which is only slightly less than the over all length of the cabinet. It will be seen that if the pipes, designated 11 and 12, had to enter the ends of the sections instead of the bottoms as shown in Figure 2, or the tops as shown in Figure 3, considerable space would be lost.

I have shown the sections as being clamped together by means of tie rods 13. The sections may be joined in any usual manner of joining radiator sections, either by push nipples, screw nipples, or gaskets may merely be interposed between the sections and the tie rods to keep the gaskets in compression. The end faces of the headers should be ground off smooth for the assembly of the sections. By reason of the fact that the overall width of the fins is made less than the overall width of the header portions, the sections can be laid on a flat grinding surface and the faces of the headers ground off without necessitating that the fins be ground, or without the fins interfering with the accurate grinding of the ends. As shown in Figures 1 and 3, the ends of the fins do not project edgewise beyond the edges of the barrel so that when the sections are laid edgewise in a crate for shipment, the weight will be carried by the stronger barrel and not by the relatively frail fins. This is a protection not only in the shipping of the sections, but in any handling which they must undergo.

In Figure 1 I have shown the radiator section set at the angle most nearly approaching the vertical plane at which it would ordinarily be set, but it might be inclined consid erably more where the cabinet will permit. It will be seen that the cold air entering the opening C will rise up in the space between the under side of the radiator and the back wall of the cabinet. It flows through the space between the fins and merges from the upper surface of the section, rising in the cabinet and escaping through the opening B. The effect produced therefore closely approximates the effect which would be procured if the section lay in a horizontal position and had vertical fins and the cabinet had a depth sufficient to accommodate the section laid in this position.

The sloping section has an advantage over a horizontal section in that the mean draft head, i. e., the distance from the bottom of the radiator to the outlet opening in the cabinet, is less with'the sloping section. A gain is secured because of the greater surface provided on a sloped section over a horizontal section in cabinets of thesame depth.

The advantage of the arrangement will be readily observed when reference is made to the curve 5. The air from the room entering the opening C rises up and under the radiator without being substantially heated until the air starts to pass through the channels between the fins. Since the maximum length of the fins is only :slightly. more than three inches, almost the entire area of the section is emitting heat onthat portion of the curve which lies between 1 and 4 on the base lineof the curve.

By reason of the angle at which the fins are set, it will be seen that where the building construction permits the cabinet to be of greater depth the radiator can be sloped to a greater extent away from a vertical plane, toward a horizontal position, and its efficiency very greatly increased. The straight fins arranged at this angle with reference to the major longitudinal axis of the section give the greatest degree of efficiency over a wide range of angular adjustment for the section. Actually, if the cabinet can be made a few inches deeper so that the inclination of the section may be greater, the efficiency of the radiator is very materially increased without varying at all the weight of the radiator, and therefore a greater heating emission can be obtained without any increase in cost whatever.

The invention lends itself very readily to commercial installation because it can be used in a cabinet space of the minimum depth found in commercial practice and have an efficiency fairly comparable to that of an assembled radiator unit made of expensive copper tubing and sheet metal fins placed in a horizontal position in the bottom of the cabinet.

It will be obvious that a cast metal section as thus arranged has a much higher efficiency than an ordinary multi-loop radiator built into a cabinet.

As indicated above, these sections are quite commonly placed in built-in cabinets formed directly in the wall of the building to be heated. This is indicated in Fig. 1 where the outside of the buildingis diagrammatically indicated. It will be quite obvious that the back wall E of the cabinet will be colder than the front wall D because of the fact that the wall D is surrounded by the air in the room. Moreover. it will be seen that heat dissipated through the wall E will be wasted, whereas heat imparted to the wall D will be radiated into the room and usefully employed. Therefore, where the section is used in a built-in cabinet of this nature, the radiator is set so that the bottom of the radiator is away from the Wall E, close to the wall D, andthe top is close to the wall E. Assume that the air in the room entering through the opening C is There is a relatively low temperature difference between this air and the wall E and the air is not very rapidly cooled, so that it does not dissipate heat through the wall E very rapidly. After the air has passed through the convector, however, and is in the space between the wall D and the top of the convector, which space is marked F, it is much hotter than 70. The wall D being in the room is not as cold as the wall E and will therefore cool this air less, and the heat absorbed by the wall D will be radiated into the room. It is consequently only desirable in such an installation to use some heat insulation at G above the top of the convector. If the radiator were sloped and the thickness of the insulation would re- 1 duce the available air circulating space in the cabinet. Therefore in using the section in a built-in cabinet, my invention contemplates that the section shall preferably be sloped in the manner shown in Figure 1.

While I have illustrated a particular preferred construction of my invention it will be understood that various modifications and changes may be made without departing from the scope of the following claims.

I claim:

1; A heating convector comprising a plurality of sections, each section having an upper and a lower header which are out of vertical alinement, and a barrel portion connecting the upper and lower headers, said barrel portion having straight fins thereon projecting from opposite sides thereof and inclined with respect to both the vertical and the horizontal axis of the section, the overall width of the barrel with the fins being less than the overall width of the header portions of the section.

2. A heating convector comprising a plurality of sections sloped with respect to a vertical plane and having fins extending thereacross, the end sections having offset connector portions projecting in a vertical direction from the end of the sections.

3. A heating convector comprising a rality of cast metal sections comprising intermediate sections and end sections. all of said sections having upper and lower header portions and intermediate barrel portions. the barrel portions having sloping fins on opposite sides thereof. the upper header portions being out of vertical. alinement with the lower header portions whereby the axis of the barrel is inclined from a vertical plane, the end sections having an off-set connector portion on one of the headers thereof. said connector portion being offset on the side of the section to which the section is inclined.

4. A heating convector installation comprising a cabinet the back wall thereof being an outside wall, said cabinet also having a front wall, there being an air inlet adjacent the bottom of the cabinet. the cabinet having an outlet at the top thereof. and a heating convector in the cabinet inclined across the cabinet with the bottom thereof adjacent the front wall and the top thereof adjacent the back wall, said radiator having a plurality of relatively thin, flat barrels turned crlgcwise in the cabinet, said barrels having laterally projecting fins thereon which slone unwardly and forwardly from the baclt wall toward the front wall, said cabinet having a layer of insulation against the back wall above the top of the convector having its lowpluer edge adjacent the top of the convector and its upper edge at the top of the cabinet.

5. A heating convector section comprising a barrel having a header portion at each end thereof with nipple ports on each side of the header, the center lines of the nipple ports coinciding with the longitudinal axis of the section, said barrel having heat dissipating fins on the sides thereof and which are inclined with respect to both the longitudinal and transverse aXes of the section, the opposite ends of the barrel having opposite edge surfaces tapered in toward the center line of the section, whereby the nipple ports may be brought into closer proximity to the sides of the cabinet in which the convector is housed.

In testimony whereof I have hereunto set my hand.

ROBERT S. WENTWORTH.

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