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Патент USA US2055838

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Sept. 29, 1936.
Filed Aug. 14, 1935
i’atented Sept.
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 appa
round heat exchange tube with an extended sur
ratus and relates more particularly to the stream
lining of heat exchange tubes such as are used in
air conditioning systems for the heating or cooling '
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
10 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 “?ns”.
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’
20 which form to the rear with respect to air flow
of round tubes and results in a gain in heat trans
fer due to the fact that the air passes in close con
face ?n 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 ex
tended 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 ex
change unit embodying the invention;
F1Figl. 2 is a sectional view along the lines 2--2‘of
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 modi?ed way of ?tting the extended
surfaces around the round tubes.
The heat exchange unit illustrated by Fig. 1,
comprises the pair of headers 5 into which the
fact with the entire tube surface of stream-lined . outer ends of the plurality of tubes 6 are ?tted.
The heating or cooling medium may enter the
25 as in the case of round tubes.
upper header 5 through the pipe 1 and after pass- 25
It has been proposed heretofore to manufacture 'ing through the tubes 6 into the lower header 5,
tubes, there being no “shadow area” to their rear
heat exchange tubes with stream-lined ‘shapes
and even to provide extended surface ?ns with
stream-lined outlines around such tubes, but the
30 cost of and the di?iculties of manufacture of such
tubes as well as the di?‘lculty of providing a group
of such tubes with headers, has prevented their
general use.
may be exhausted through the pipe 8.
As shown by Figs. 2 and 3, the plurality of ex
tended surface sheets 9 are placed in spaced rela
tionship 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 cir- '
cular openings ID of substantially the same diam
According to this invention, a plurality of round-v eter as the outer diameter of the tubes 6 and the
35 tubes is provided throughout their'length with sheets are forced over the tubes in order that 35.
stream-lined air contacting portions by a plu
rality 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
45 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 stream
lined indentations provide the round tubes be
50 tween 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
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 cir
cular opening for the reception of a round tube,
as shown in plan view'by Fig. 2, and in section
and in pro?le 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 stream‘
lined 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.
pair of extended surface sheets extending cross
wise said tubes, one of said sheets having formed
as integral parts thereof thin walled substantially
Whereas one or more embodiments of the in
venticn have been described for the purpose of
illustration, it should be ‘understood that the in
vention is not to be limited to the exact arrange
tubes between it and the other of said sheets.
3. A heat exchange tube assembly comprising
a plurality of substantially round tubes,aand an
extended surface sheet extending cross-wise said
'- ment disclosed as many departures will suggest
10 themselves to those skilled in the art after having
rality of indented portions forming substantially
streamslined enclosures for the portions of said
tubes, said sheet having formed therein, a plu
had access to this disclosure.
stream-lined enclosures for portions of said tubes.
4. A heat exchange tube assembly comprising
1. A heat exchangetube assembly comprising‘ a plurality of substantially round tubes, a pair
' a plurality of substantially round tubes, and an of extended surface sheets extending cross-wise
extended surface metal sheet extending crosswise said tubes, and means comprising portions of one 15
said tubes, said sheet having attached thereto sub
of said sheets forming substantially stream-lined
stantially stream-lined sheet metal enclosures for
thin walled enclosures for said tubes between said
portions of said tubes.
What is claimed is:
2. A heat exchange tube assembly comprising
I) a plurality of substantially round tubes, and a
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