US2055838A - Heat exchange apparatus - Google Patents

Description

Sept. 29, 1936. H ERG A HEAT EXCHANGE APPARATUS Filed Aug. 14, 1935 I iatented Sept. 1936' UNITED STATES HEAT EXCHANGE APPARATUS Lawrence H. Frltzberg, Hyde Park,

Mass, as-

signor to B. F. Sturtcvant Company, Inc.,

Boston, Mass.

Application August 14, 1935, Serial No. 36,091 4 Claims. (01. 257-262) This invention relates to heat exchange apparatus and relates more particularly to the streamlining of heat exchange tubes such as are used in air conditioning systems for the heating or cooling 5 of air.

In many air conditioning systems, it is desired to obtain the heat exchange effect by forcing the air to be conditioned over heat exchange tubes through which is circulated a cooling or heating medium depending upon the duty required. In order to obtain the maximum heat transfer from air to tube or tube to air, as the case may be, it has been customary to provide the tubes with a plurality of spaced extended surfaces known more generally as fins.

It is desirable especially where the air is moved at high velocities to stream line the heat exchange coils. Streamlining results in a saving in fan power due to the elimination of theeddy currents which form to the rear with respect to air flow of round tubes and results in a gain in heat transfer due to the fact that the air passes in close confact with the entire tube surface of stream-lined tubes, there being no shadow area to their rear as in the case of round tubes.

It has been proposed heretofore to manufacture heat exchange tubes with stream-lined shapes and even to provide extended surface fins with stream-lined outlines around such tubes, but the cost of and the difiiculties of manufacture of such tubes as well as the difilculty of providing a group of such tubes with headers, has prevented their general use.

According to this invention, a plurality of round-v tubes is provided throughout their'length with stream-lined air contacting portions by a plurality of spaced extended surface plates or sheets which are common to the plurality of tubes and which form between themselves stream-lined en- 40 closures for the tubes.

In one embodiment of the invention, a plurality of extended surface metal sheets is placed in spaced relationship around a plurality of tubes, the sheets being provided with round openings to receive the tubes. In the sheet around each round opening, a streamlined indentation is made with a depth corresponding to the width between the spaced sheets. When assembled the streamlined indentations provide the round tubes between the extended surfaces with stream-lined external contours.

An object of the invention is to provide round heat exchange tubes with efficient, inexpensive stream-lined enclosures.

Another object of the invention is to provide a round heat exchange tube with an extended surface fin which stream-lines a portion of the tube.

Another object of the invention. is to provide a plurality of round tubes with a plurality of extended surface sheets which provide therebetween 5 stream-lined enclosures for the tubes.

Other objects of the invention will be apparent from the following description taken together with the drawing.

The invention will now be described with refer- 10 ence to the drawing of which:

Fig. 1 is a side view of an assembled heat exchange unit embodying the invention;

F1Figl. 2 is a sectional view along the lines 2--2of Fig. 3 is a sectional view along the lines 3-4 of Fig. 2, and

Fig. 4 is a sectional view similar to Fig. 3 and illustrates a modified way of fitting the extended surfaces around the round tubes. 20

The heat exchange unit illustrated by Fig. 1, comprises the pair of headers 5 into which the outer ends of the plurality of tubes 6 are fitted.

The heating or cooling medium may enter the upper header 5 through the pipe 1 and after pass- 25 'ing through the tubes 6 into the lower header 5,

may be exhausted through the pipe 8. v

As shown by Figs. 2 and 3, the plurality of extended surface sheets 9 are placed in spaced relationship longitudinally of the tubes. In the em- 30 bodiment illustrated, each sheet 9 is common to all of the tubes. The sheets 9 are provided with circular openings ID of substantially the same diameter as the outer diameter of the tubes 6 and the sheets are forced over the tubes in order that 35.

effective contact for heat transfer purposes may be obtained. of course, the sheets l0 could be soldered to or otherwise suitably attached to the I tubes 6.

Each sheet In prior to assembly on the tubes 40 is pressed in the shop to have the indented stream-lined portions H formed around each circular opening for the reception of a round tube, as shown in plan view'by Fig. 2, and in section and in profile by Fig. 3. The indented portions 45 II have a depth equal to the desired spacing between the extended surfaces with the result that when the sheets 9 are assembled upon the tubes 6, the indented portions it provide streamlined enclosures around the tubes 6, between the 50 sheets 9.

In the embodiment illustrated by Fig. 4, the circular openings in the sheets 9 for the reception of the tubes 6, have around their circumferences the in-turned portions 8 2 which extend in contact 55 with the outer surfaces of the tubes 6, between the sheets 9. In this way, a greater surface of contact between the tubes 6 and the extended surface sheets 8, is provided.

Whereas one or more embodiments of the inventicn have been described for the purpose of illustration, it should be understood that the invention is not to be limited to the exact arrangement disclosed as many departures will suggest themselves to those skilled in the art after having had access to this disclosure.

What is claimed is:

1. A heat exchangetube assembly comprising a plurality of substantially round tubes, and an extended surface metal sheet extending crosswise said tubes, said sheet having attached thereto substantially stream-lined sheet metal enclosures for portions of said tubes.

2. A heat exchange tube assembly comprising I) a plurality of substantially round tubes, and a pair of extended surface sheets extending crosswise said tubes, one of said sheets having formed as integral parts thereof thin walled substantially stream lined enclosures for the portions of said tubes between it and the other of said sheets.

3. A heat exchange tube assembly comprising a plurality of substantially round tubes, and an extended surface sheet extending cross-wise said tubes, said sheet having formed therein, a plurality of indented portions forming substantially stream-lined enclosures for portions of said tubes.

4. A heat exchange tube assembly comprising a plurality of substantially round tubes, a pair of extended surface sheets extending cross-wise said tubes, and means comprising portions of one of said sheets forming substantially stream-lined thin walled enclosures for said tubes between said sheets.

LAWRENCE H. FRITZBERG.

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