US 2664274 A
Description (OCR text may contain errors)
Dec. 29, 1953 G. A. WORN ET AL A METHOD AND APPARATUS EMPLOYING soNIc wAvEs 1N HEAT EXCHANGE 2 Sheets-Sheet 1 Filed Dec. 22, 1951 lNvENToRs 660g@ War/q @nit Dec. 29, 1953 G. A. woRN ETAL 2,664,274
METHOD AND APPARATUS EMPLOYING SONIC WAVES IN HEAT EXCHANGE 2 Sheets-Sheet 2 Filed DSC. 22, 1951 30 INVENToRs George# 0172 Patentedl Dec. 29, V1953 METHOD AND APPARATUS EMPLOYING SONIC WAVES IN HEAT EXCHANGE George A. Worn, Greenwich, Conn., and Frank L. Rubin, Brooklyn, N. Y., assignors to The Lummus Company, New York, N. Y., a corporation of Delaware Application December 22, 1951, Serial No. 262,948
This invention relates to improvements in lndirect heat transfer wherein the transfer is effected between two fluids separated by a heatconducting wall. More particularly, the invention is concerned with effecting Ycontact of at least one of the fluids with said wall in a manner to increase the efficiency of the heat transfer.
Important objects of the invention are, to provide for said improved Contact and increased eiliciency of heat transfer by producing waves of the nature of sound waves in the fluid; to provide for production and direction of said waves in a manner to obtain the maximum desired result with a minimum input of power; to provide for the production of said waves in a manner to avoid vibration of an exchanger structure in which the heat transfer is effected; to provide for employment of the principle of resonance to reinforce the waves and further increase the heat transfer efficiency; and to provide for satisfactory production and utilization of the waves in the tube-side fluid of an exchanger wherein one of the fluids is conducted through a bundle of tubes.
Other objects of the invention will appear from the following description taken with the accompanying drawings.
In the drawings:
Fig. l is a longitudinal section of a heat exchanger equipped for conducting the heat transfer according to the invention.
Fig. 2 is a view similar to Fig. l showing the heat exchanger modified for employing the principle of resonance.
Fig. 3 is a sectional view of an end portion of the heat exchanger showing another modification thereof for employing the principle of resonance.
Fig. 4 is a section on the line llof Fig. 3.
Fig. 5 is a view similar to Fig. 1 showing a heat exchanger of the U-tube type equipped for conducting the heat transfer according to the invention.
Fig. 6 is a sectional view of an end portion of a heat exchanger of the type shown in Fig. 5 showing a modification thereof.
The structure of the exchanger illustrated in Fig. l includes a shell which may be cylindrical or of other suitable form and has nozzles 2 and 3 for passing fluid through it. At one end of the shell there is a channel or header formedby an annular member 4, a tube sheet 5 and a cover plate 6. As shown, the tube sheet 5 is welded to the shell, the annular member is bolted to the tube sheet, and the cover plate is bolted to the annular member with gaskets between the bolted members. These structural details may be modified, however. At the opposite end of the shell a tube sheet 'I is welded or otherwise suitably secured to the shell and a bundle of substantially parallel tubes 8 within the shell are connected at their opposite ends to the tube sheets 5 and 'I, respectively. A channel member 9 is bolted or otherwise suitably secured over the outer face of the tube sheet l, with a gasket interposed. The exchanger is shown as vertical but it may be otherwise disposed. The upper channel has an inlet nozzle I0 and an outlet nozzle I I and a pass partition l2 dividing the channel into two cornpartments I3 and I4. Nozzle I0 opens into the compartment I3 and nozzle II opens from the compartment I4. One half of the tubes open from the compartment I3 and the other half open into the compartment I4. The lower channel forms a single chamber with which all of the tubes communicate. The tube bundle may be substantially circular in cross section.
The channel member 9 'is cup-shaped and has a smooth inner surface I5 which is paraboloidal, or substantially so. This surface faces the tube sheet 'I, is coaxial with the tube bundle and its projected area is sufficient to take in the projected area of the adjacent end of the bundle. At the focus of the paraboloid of said surface, or approximately so, there is disposed a device Iii for initiating sonic waves in the fluid within the lower` channel. This device may be of any suitable character. For example, it may be an electrically or mechanically operated vibrator or a wind instrument. As anl electrically operated vibrator it may be of the piezo-electric type employing a transducer of quartz, ceramic or other suitable material. The device is shown as provided with a tubular supporting stem projecting through an aperture in the member 9 and secured therein. Wires II are shown extending into the stem to supply electric current for operating the device. In the operation of the heat exchanger, the shell-side uid is circulated through the shell, via the nozzles 2 and 3, to surround the tubes of the bundle and, if desired, suitable baffles, not shown, for the fluid may be employed within the shell. The tube-side-fluid is passed through the nozzle I0, thechannel compartment I3 and one group of the tubes 8 to the lower channel. Thence, it is passed through the other group of tubes, the channel compartment I4 and the out let nozzle II. While said fluids are being passed through the exchanger, the device I6 is continuously operated to initiate waves of the nature of sound waves in the tube-side fluid within the lm of the fluid from forming on the tube wall and prevent deposit of solid matter, both of which reduce heat exchange efliciency.y
Waves of sonic, ultrasonic or subsonic frequency may be employed for said purposes depending upon the character of the tubeside fluid, its operating temperature A and other factors. Hereinafter in the specification and claims the term sonic is intended to include waves of any frequency which are of the nature of sound Waves. The invention particularly contemplates the use of a tubeside uid in gaseous state such as vapors or gases of various kinds. However, liquid may be used.
The invention further provides for mounting of a vibrator device for producing the waves in a posltion spaced from all parts of the heat exchanger, as shown in the drawing, to avoid transmission of the vibrations to the heat exchanger structure and possible damage thereof. The location of said device in the return channel of the exchanger is also particularly advantageous for the reason that it enables a single device and a single reflector to propagate the waves through all of the tubes of the bundle. The location of the device also renders it conveniently accessible by unbolting and removing the channel member 9.
The invention also comprehends employment of the principle of resonance whereby the waves passing through the tubes from the reflector l5, or directly from the device I6 may be reinforced by reflected, or echo, waves passing in the opposite direction. For that purpose, the channel cover B may be so spaced from the tubes, with reference to the wave length as to reflect the Waves in the required phase relation to the original waves to effect reinforcement of the latter and further increase the heat transfer eiciency of the contact of the medium within the tubes. Fig. 2 shows provision for obtaining resonance from different Wave lengths. Within each of the channel compartments I3 and Ill there is a plate I8 having an area substantially equal to the cross section of the respective compartment. Each plate is adjustable toward and from the tubes by screws I9. These are in screw-threaded connection with the channel cover 6 and have swivel connections with the plate I 8. The plates I8 serve as reflecting surfaces for the waves coming from the tubes and may be adjusted a proper distance from the tubes to establish resonance relation between the reflected waves and the oncoming Waves to reinforce the latter. The term resonance used in the specification and claims is to be understood as applying to the reinforcement of waves of any suitable frequency according to the principle of resonance and as not limited to waves of sonic frequency.
Provision for more flexible adjustment of wave reflection is shown in Figs. 3 and 4. There4i in each kof the compartments there is a number of reflecting plates which are-individually adjustable. these plates, designated I8a Ib and I8c in each In the present instance, there are three of.
4 l compartment. Plates lila and i817 are segmental in form and plate I8c is semicircular. All of the plates are shown as concentric and screws lQa are provided to adjust them individually toward and from the tubes, as in the case of the plates I8 of Fig. 2. The plates IBa, I8b and I8c have flanges upon their back faces to avoid a gap when one of the plates is adjusted a substantial distance farther than an adjacent plate. Of course, the shape and number of the plates may be Varied to suit conditions such as variations in the tube layout and in the shape of the channel The plates may also be adjusted by means other than the screws.
Fig. 5 shows an adaptation of the invention to a heat exchanger having U-tubes. The exchanger structure shown includes a shell 2i closed at one end having a tube sheet 22 Welded or otherwise suitably secured to its opposite end. A bundle of U-tubes 23' have their ends secured in the tube sheet and opening into a channel defined by a member 2li bolted or otherwise suitably secured to the tube sheet. A pass partition 25 divides the interior of the channel member into two compartments 25 and 2l and one leg of the tubes opens into one of said compartments and the other into the other compartment. The member 2Q has nozzles 28 and 29 opening into the compartments .23 and 2l respectively, to circulate fluid through the tubes. The shell 2l has a longitudinal partition 30 extending from the tube sheet 22 and between the legs of the tubes. At opposite sides of the partition the shell has nozzles 3| and 32, for circulating fluid through the shell and around the outer surfaces of the tubes.
The channel member 21% has two internal reflecting surfaces 33 within the respective channel compartments and facing the tubes. Each of the surfaces forms approximately half of a paraboloid and the two surfaces together form approximately a complete paraboloid. At cpposite sides of the pass partition 25 two devices similar to the device I6 of Fig. 1, and similarly designated, are mounted in the region of the focus of the paraboloid to initiate sonic waves which are reflected by the surfaces 33 substantially in parallel into both legs of all of the tubes of the bundle. Thereby, as described in connection with Fig. 1, a molecular agitation of the uid Within the tubes will be caused and the heat exchange eiciency will be increased. In Fig. 6 only one of the devices IS is employed to initiate the waves. Said device is disposed in one of the channel compartments. In some cases a single device will be su'cient to send the waves through the U-tubes. As in the case of the operation of the exchanger shown in Figs. l and 2 the use of a tube-side fluid in gaseous state lis particularly contemplated but liquid may be used.
VIt is, of course, to be understood that the present disclosure of the invention is merely illustrative and in nowise limiting and that the invention comprehends such modifications as will fall within the scope of the claims.
1. In the operation of a heat exchanger having a group of substantially parallel tubes and means including a channel chamber at one end of the tubes to pass a fluid through the tubes and in which there is provision for fluid with the exterior of ,said tubes in indirect heat exchange relation with the first-mentioned fluid, the improvement comprising initiating sonic waves in the tube-side fluid within a region withccntact of other in said chamber small in comparison with the chamber and spaced from the tubes longitudinally of the latter, and reflecting said waves Within said chamber predominantly longitudinally of the tubes and into the latter to increase 'the heat transfer efiiciency of the contact of the tube-side uid with the inner Walls of the tubes.
2. In the operation of a heat exchanger according to claim 1, the improvement claimed therein wherein said waves are of ultrasonic frequency.
3. In the operation of a heat exchanger according to claim 1, the improvement claimed therein wherein the tube-side fluid is in a gaseous state.
4. In the operation of a heat exchanger according to claim 1, the improvement claimed therein wherein the said waves are of ultrasonic frequency and the tube-side uid is in a gaseous state.
5. In the operation of a heat exchanger having a group of substantially parallel tubes and means including a channel chamber at one end of the tubes to pass a iiuid through the tubes and in which there is provision for contact of other uid with the exterior of said tubes in indirect heat exchange relation with the first-mentioned fluid, the improvement comprising initiating sonic Waves in the tube-side fluid in said chamber at a point surrounded by said fluid and clear of the chamber walls and spaced from the tubes, and directing said waves Within said chamber predominantly longitudinally of the tubes and into the latter to increase the heat exchange efciency of the contact of the tube-side fluid with the inner Walls of the tubes.
6. In the operation of a heat exchanger having a group of4 substantially parallel tubes and means including a channel chamber at one end of the group and a channel chamber at the opposite end of the group to pass a fluid through the tubes, and in which there is provision for contact of other fluid with the exterior of said tubes in indirect heat exchange relation vvith the first-mentioned fluid, the improvement comprising initiating sonic waves within the tube-side fluid in one "of said chambers at a point surrounded by said fluid and clear of the chamber walls and spaced from the tubes, directing the Waves in said chamber predominantly longitudinally of the tubes and into the latter for advance therethrough to increase the heat exchange eiiiciency of the contact of the tube-side fluid with the inner Walls of the tubes, within the other of said chambers, reecting said waves reversely into the tubes, and adjusting said reflection to produce resonance of the reflected waves with the waves advanced through the tubes.
7. In a heat exchanger having a group of substantially parallel tubes, means including a channel chamber at one end of the tubes for passing a uid through the tubes, and in which there is provision for contact of other fluid with the exterior of said tubes in indirect heat exchange relation with the mst-mentioned fluid, the improvement comprising a device Within said chamber operable to initiate sonic waves in the tube-side Iiuid at a point clear of the Walls of said chamber and spaced from the tubes longitudinally of the latter, the area of said device projected longitudinally of the tubes being small as compared With that of said chamber and that of the group of tubes, and reflecting means within the chamber formed and disposed to reect said Waves predominantly longitudinally of the tubes and into the latter, to increase the heat transfer etliciency of the contact of the tube-side iluid with the inner Walls of the tubes.
8. In a heat exchanger according to claim 7, the improvement claimed in said claim wherein said reiiecting means has a paraboloidal surface facing said end of the tubes and said waveinitiating device is located in the region of the focus of said surface.
9. In a heat exchanger having a group of substantially parallel tubes and means including a channel chamber at one end of the group and a channel chamber at the opposite end of the group to pass a huid through the tubes, and in which there is provision for contact of other iluid with the exterior of said tubes in indirect heat exchange relation with the first-mentioned uid, the improvement comprising a device within one of said chambers operable to initiate sonic Waves in the tube-side fluid at a point clear of the Walls of said chamber and spaced from the tubes longitudinally of the latter, the area of said device projected longitudinally of the tubes being small as compared with that of said chamber and that of the group of tubes, renecting means within said chamber formed and disposed to reflect said Waves predominantly longitudinally of the tubes into the latter for passage therethrough, to increase the heat transfer efciency of the tubeside fluid with the inner Walls of the tubes, reilecting means in the other of said chambers disposed to receive said waves transmitted through the tubes and reflect them back through the tubes, and means to adjust the second-mentioned reflecting means toward and from the tubes to produce resonance of the waves reflected thereby With the oncoming waves.
GEORGE A. WORN. FRANK L. RUBIN.
References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,570,781 Ruben Jan. 26, 1926 1,834,875 Schaafhausen Dec. 1, 1931 1,982,341 Hitchcock Nov. 27, 1934 2,351,163 Thomas June 13, 1944 2,489,944 Worn et al. Nov. 29, 1949 2,514,797 Robinson July 11, 1950 2,523,174 Worn Sept. 19, 1950 FOREIGN PATENTS Number Country Date 532,144 Great Britain Jan. 17, 1941