US3610333A - Tubular-type heat-exchange apparatus - Google Patents

Tubular-type heat-exchange apparatus Download PDF

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US3610333A
US3610333A US855722A US3610333DA US3610333A US 3610333 A US3610333 A US 3610333A US 855722 A US855722 A US 855722A US 3610333D A US3610333D A US 3610333DA US 3610333 A US3610333 A US 3610333A
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flues
flue
supply
discharge
gas
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US855722A
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Leonard A Fisher
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H B SMITH CO Inc
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H B SMITH CO Inc
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28FDETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/02Header boxes; End plates
    • F28F9/026Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits
    • F28F9/0263Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits by varying the geometry or cross-section of header box
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28FDETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F13/06Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S165/00Heat exchange
    • Y10S165/454Heat exchange having side-by-side conduits structure or conduit section
    • Y10S165/471Plural parallel conduits joined by manifold

Definitions

  • This invention relates to heat-exchange apparatus, for specific example, a parallel-flue boiler having a plurality of parallel flues spaced from each other and which are of the same transverse cross-sectional area, each of which communicates at one end with a supply flue and at the other end with a delivery or discharge flue.
  • the object of the present invention is to provide heatexchange apparatus of the parallel-flue type and of such construction that the total quantity of the heating gas which passes through the apparatus, per unit of time, will be equally distributed among the several parallel flues.
  • the heating fluid which would usually be a gaseous product of combustion, and thus a gaseous fluid, will herein be referred to merely as gas.”
  • FIG. 1 is a diagrammatic vertical section, in a plane which passes through the axes of the parallel flues, illustrating a fiveflue boiler according to the present invention
  • FIG. 2 is a diagram illustrative of the comparative quantity of gas which passes, per unit of time, through the several parallel flues;
  • FIG. 3 is a view similar to FIG. 1, but showing a conventional boiler of the usual type.
  • H0. 4 is a diagram, similar to FIG. 2 showing the relative amount of gas which passes trough the several flues of the boiler of FIG. 3.
  • FIG. 3 which illustrates a boiler of conventional type, would expect that fluid entering the supply flue S at X and passing through the parallel flues to the discharge flue D, would divide itself equally between the several parallel flues, but this would not be truev What' actually would occur would be that the first of the series of parallel tubes (that is the tube nearest to the intake point X, would carry the least amount of gas, while the last of the series would carry the greatest quantity.
  • the temperature of the hot gas, entering the supply flue S at the point X would be higher than that of the gas leaving the discharge flue D at the point Y.
  • the temperature of combustion products of a burner, entering at X would normally be approximately 3,200 F., and it may be assumed that the temperature of the gas at the points 1, 2, 3, 4 and 5, of the supply flue S would be about the same.
  • the temperature at each of the points 10, 9, 8, 7 and 6 of the delivery flue D would be nearly equal and probably approximately 400 F.
  • the density of the gas at the points Y, 6, 7, 8, 9 and 10 would be greater than at the points X, l. 2, 3, 4 and 5, in an inverse ratio to the absolute temperatures.
  • a heat exchanger comprising spaced parallel flues of uniform cross section, one of which constitutes a supply flue and the other a discharge flue, and a plurality of spaced parallel transfer flues situated between the supply and discharge flues with the ends of each of the transfer flues connected with the supply and discharge flues and perpendicular thereto, the supply and discharge flues having inlet and outlet openings and being positioned with the inlet and outlet openings at the same end so that the gas entering the inlet opening of the supply flue flows along the supply flue, then through the transfer flues, then into and along the discharge flue and finally out through outlet opening so as to reverse the gas flow; characterized in that the cross section of the discharge flue is less than that of the supply flue in such proportion that the heated gas which enters the supply flue is divided equally among the several parallel flues on its way to the discharge flue.
  • a heat exchanger comprising spaced parallel flues of uniform cross section, one of which constitutes a supply flue and the other a discharge flue and n spaced parallel transfer flues arranged with their axes perpendicular to the axes of the supply and discharge flues and with their ends in communication with the supply and discharge flues, the supply and discharge flues having inlet and outlet openings and being positioned with the inlet and outlet openings at the same end so that the gas entering the inlet opening of the supply flue flows along the supply flue, then through the transfer flues,
  • said inlet and outlet openings comprising open ends preceding the first of the n spaced transfer flues and closed ends following the last of the n spaced transfer flues, and wherein the cross-sectional area of the discharge flue is less than the cross-sectional area of the supply flue in such proportion that at the intersections of the opposite ends of each one of said n transfer flues with the supply and discharge flues, respectively, the dynamic pressure of the heated gas is the same.
  • T, and T are the absolute temperatures, at the entrance end of the supply flue and the delivery end of the discharge flue, respectively.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Geometry (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Abstract

Heat-exchange apparatus of a kind wherein a substance is heated by the flow of a hot gaseous fluid through a series of like, spaced, parallel flues which pass through the substance to be heated and wherein each of the parallel flues communicates at one end with a supply flue and at its opposite end with a delivery flue, and wherein the supply and delivery flues are so relatively arranged and are so proportioned, as to relative transverse area from point-to-point, that an equal quantity of the gaseous fluid flows through each of the parallel flues per unit of time.

Description

United States Patent TUBULAR-TYPE HEAT-EXCHANGE APPARATUS 5 Claims, 4 Drawing Figs.
U.S. C1 165/175,
122/155, 165/1 Int. Cl F28f 9/00 Field of Search... 165/ l 74,
[56] References Cited FOREIGN PATENTS 192,936 11/1957 Austria 165/175 1,396,215 3/1965 France 165/175 Primary Examiner-Albert W. Davis, Jr. Attorney-Roberts, Cushman & Graver ABSTRACT: Heat-exchange apparatus of a kind wherein a substance is heated by the flow of a hot gaseous fluid through a series of like, spaced, parallel flues which pass through the substance to be heated and wherein each of the parallel flues communicates at one end with a supply flue and at its opposite end with a delivery flue, and wherein the supply and delivery flues are so relatively arranged and are so proportioned, as to relative transverse area from point-to-point, that an equal quantity of the gaseous fluid flows through each of the parallel flues per unit of time.
TUBULAR-TYPE HEAT-EXCHANGE APPARATUS This invention relates to heat-exchange apparatus, for specific example, a parallel-flue boiler having a plurality of parallel flues spaced from each other and which are of the same transverse cross-sectional area, each of which communicates at one end with a supply flue and at the other end with a delivery or discharge flue. For heating efficiency an equal quantity of the gaseous heating fluid should pass through each of the parallel flues per unit of time, and this means that the pressure differential between the receiving and delivery ends of each respective one of the parallel flues must be alike, but this high efficiency is not attained in customary devices of this type wherein the supply and delivery flues are of the same diameter and in which the gaseous heating fluid flows in the same direction through the supply and the delivery flues.
This lack of efficiency is due, primarily, to the fact that the several flues do not conduct the same quantity of gas per unit of time.
The object of the present invention is to provide heatexchange apparatus of the parallel-flue type and of such construction that the total quantity of the heating gas which passes through the apparatus, per unit of time, will be equally distributed among the several parallel flues.
For convenience in description but without limiting in text, the heating fluid, which would usually be a gaseous product of combustion, and thus a gaseous fluid, will herein be referred to merely as gas."
ln the accompanying drawing:
FIG. 1 is a diagrammatic vertical section, in a plane which passes through the axes of the parallel flues, illustrating a fiveflue boiler according to the present invention;
FIG. 2 is a diagram illustrative of the comparative quantity of gas which passes, per unit of time, through the several parallel flues;
FIG. 3 is a view similar to FIG. 1, but showing a conventional boiler of the usual type; and
H0. 4 is a diagram, similar to FIG. 2 showing the relative amount of gas which passes trough the several flues of the boiler of FIG. 3.
One unfamiliar with apparatus of this type, in looking at FIG. 3, which illustrates a boiler of conventional type, would expect that fluid entering the supply flue S at X and passing through the parallel flues to the discharge flue D, would divide itself equally between the several parallel flues, but this would not be truev What' actually would occur would be that the first of the series of parallel tubes (that is the tube nearest to the intake point X, would carry the least amount of gas, while the last of the series would carry the greatest quantity.
This result is because of the dynamic pressure increase between the inlet end 1 of the supply flue and the dead end 5 of the supply flue, and the dynamic pressure loss between the points 6 and 10 of the discharge flue.
Assuming that the pressure at the point 1 is P, and the dynamic pressure of the entering gas at the point 1 is represented by the expression A,V,/2gc, (where Ais the density of the gas) then. since the velocity V decreases approximately to zero at the point 5, (because of the loss of gas through the several parallel flues) and because of the resultant conversion of kinetic energy into pressure, the pressure at the point 5 is represented by the expression P,+A, Vfi/Zgc On the contrary, in the discharge flue, the velocity will increase from the point 6 to the point 10, (because of the influx of gas along the discharge flue D) so teat the pressure differential between the points 5 and 10 will exceed the pressure differential between the points 1 and 6 by 517%;- Ami 2, Zgc
Thus the flow rate in the last of the parallel flues (between the points 5 and 10) will exceed the flow rate between points 4 and 9, etc., until the lowest flow rate will be from 1 to 6. This nonuniform distribution of hot gas is graphically illustrated in FIG. 4. v
By rearranging the discharge flue D as shown in FIG. 1, and by properly proportioning the cross-sectional areas of the supply and discharge flues S and D, the pressure drop along each of the parallel flues may be made equal.
Referring to FIG. 1, if the density of the gas at the inlet point X and at the discharge point Y, were equal, then the transverse areas at those points should be equal so that P,,P,=A,V /2gc while P,,,P =A, V,"'/2gc which would assure thatP,-P P,P,,,. Similarly, it may be shown that all of the parallel flues would show the same pressure differential and therefore have equal flow rates.
in proof of the possibility of attaining the above results, certain assumptions based on observed facts may be made.
In a heat exchanger such as a boiler or furnace, the temperature of the hot gas, entering the supply flue S at the point X would be higher than that of the gas leaving the discharge flue D at the point Y. For example, the temperature of combustion products of a burner, entering at X would normally be approximately 3,200 F., and it may be assumed that the temperature of the gas at the points 1, 2, 3, 4 and 5, of the supply flue S would be about the same. Assuming that the flow rate of the gas through each of the parallel flues is the same, the temperature at each of the points 10, 9, 8, 7 and 6 of the delivery flue D would be nearly equal and probably approximately 400 F.
The density of the gas at the points Y, 6, 7, 8, 9 and 10 would be greater than at the points X, l. 2, 3, 4 and 5, in an inverse ratio to the absolute temperatures.
Thus, for example, and employing the symbol A as indicating density, and Tindicating absolute temperature,
in order to maintain equal pressure differentials through each of the parallel flues, it is necessary that the-dynamic pressure at the points 1 and 6; 2 and 7-5 and 10, etc. be equal, that is to say l A,V,=A,V,, etc.
Since under a steady-flow condition, the entire mass flow entering at X and leaving at Y is the same, and designating the transverse area of the flue S by the character N, at the point 1, and the transverse area at the point 6 by N -then N, would equal N and A,N, V,=A,,N,, V
Now referring to equations l and (2) supra,
L5 A, V.,
Then
- a N6 Al and In the example above cited l Then by making the transverse flue areas N, and N,,, at the points 1 and 6, respectively, in accordance with the formula equal, and in the same way the dynamic pressure at thepoints 2 and 7, 3 and 8, etc. will be equal.
For instance, with five parallel flues as shown in FIG. 1 and each carrying one-fifth of the totalvolume of flow, the axial velocity V =0.8 V,, and the axial velocity V =0,8 V Since T,= T and Tan, etc.
Then A,=A, and A =A etc.
Substituting in equation l) A,V, A,,V,, A V, =A V A V, /0.8=A, V,,'-/0.8
A, V =A-, V Likewise A V A V etc Thus, by arranging the supply and discharge flues so thatgas flows in opposite directions and by proportioning the supply flue S and the discharge flue D according to the equation N n l where n represents any number of parallel flues; a boiler may be manufactured wherein the flow through each of the parallel flues will be the same.
What I claim is:
l. A heat exchanger comprising spaced parallel flues of uniform cross section, one of which constitutes a supply flue and the other a discharge flue, and a plurality of spaced parallel transfer flues situated between the supply and discharge flues with the ends of each of the transfer flues connected with the supply and discharge flues and perpendicular thereto, the supply and discharge flues having inlet and outlet openings and being positioned with the inlet and outlet openings at the same end so that the gas entering the inlet opening of the supply flue flows along the supply flue, then through the transfer flues, then into and along the discharge flue and finally out through outlet opening so as to reverse the gas flow; characterized in that the cross section of the discharge flue is less than that of the supply flue in such proportion that the heated gas which enters the supply flue is divided equally among the several parallel flues on its way to the discharge flue.
2. A heat exchanger comprising spaced parallel flues of uniform cross section, one of which constitutes a supply flue and the other a discharge flue and n spaced parallel transfer flues arranged with their axes perpendicular to the axes of the supply and discharge flues and with their ends in communication with the supply and discharge flues, the supply and discharge flues having inlet and outlet openings and being positioned with the inlet and outlet openings at the same end so that the gas entering the inlet opening of the supply flue flows along the supply flue, then through the transfer flues,
then into and along the discharge flue and'finally out through outlet opening so as to reverse the gas flow, said inlet and outlet openings comprising open ends preceding the first of the n spaced transfer flues and closed ends following the last of the n spaced transfer flues, and wherein the cross-sectional area of the discharge flue is less than the cross-sectional area of the supply flue in such proportion that at the intersections of the opposite ends of each one of said n transfer flues with the supply and discharge flues, respectively, the dynamic pressure of the heated gas is the same.
3. The combination according to claim 2, wherein there are n parallel flues; characterized in that the cross-sectional areas N, and N of the supply and discharge flues are proportioned in accordance with the formula a 1- n I where A, is the density of the hot gas where it enters the first of the parallel flues, and A is the density of the gas where it leaves the n"' flue of the series.
4. The combination according to claim 2, and wherein there are five of the parallel flues, and wherein the gas enters the supply flue at a temperature of approximately 3,200 F. and leaves the discharge flue at a temperature of approximately 400 F., and wherein the cross-sectional areas N, and N of the supply and discharge flues at their inlet and outlet ends, respectively, are proportioned in accordance with the formula N,/N=2.07.
5. The combination, according to claim 2, further characterized in that the transverse area N, of the supply flue is related to the transverse area of the discharge flue in accordance with the formula & a
where T, and T, are the absolute temperatures, at the entrance end of the supply flue and the delivery end of the discharge flue, respectively,

Claims (5)

1. A heat exchanger comprising spaced parallel flues of uniform cross section, one of which constitutes a supply flue and the other a discharge flue, and a plurality of spaced parallel transfer flues situated between the supply and discharge flues with the ends of each of the transfer flues connected with the supply and discharge flues and perpendicular thereto, the supply and discharge flues having inlet and outlet openings and being positioned with the inlet and outlet openings at the same end so that the gas entering the inlet opening of the supply flue flows along the supply flue, then through the transfer flues, then into and along the discharge flue and finally out through outlet opening so as to reverse the gas flow; characterized in that the cross section of the discharge flue is less than that of the supply flue in such proportion that the heated gas which enters the supply flue is divided equally among the several parallel flues on its way to the discharge flue.
2. A heat exchanger comprising spaced parallel flues of uniform cross section, one of which constitutes a supply flue and the other a discharge flue and n spaced parallel transfer flues arranged with their axes perpendicular to the axes of the supply and discharge flues and with their ends in communication with the supply and discharge flues, the supply and discharge flues having inlet and outlet openings and being positioned with the inlet and outlet openings at the same end so that the gas entering the inlet opening of the supply flue flows along the supply flue, then through the transfer flues, then into and along the discharge flue and finally out through outlet opening so as to reverse the gas flow, said inlet and outlet openings comprising open ends preceding the first of the n spaced transfer flues and closed ends following the last of the n spaced transfer flues, and wherein the cross-sectional area of the discharge flue is less than the cross-sectional area of the supply flue in such proportion that at the intersections of the opposite ends of each one of said n transfer flues with the supply and discharge flues, respectively, the dynamic pressure of the heated gas is the same.
3. The combination according to claim 2, wherein there are n parallel flues; characterized in that the cross-sectional areas N1 and Nn of the supply and discharge flues are proportioned in accordance with the formula where Delta 1 is the density of the hot gas where it enters the first of the parallel flues, and Delta n is the density of the gas where it leaves the nth flue of the series.
4. The combination according to claim 2, and wherein there are five of the parallel flues, and wherein the gas enters the supply flue at a temperature of approximately 3,200* F. and leaves the discharge flue at a temperature of approximately 400* F., and wherein the cross-sectional areas N1 and N6 of the supply and discharge flues at their inlet and outlet ends, respectively, are proportioned in accordance with the formula N1/N6 2.07.
5. The combination, according to claim 2, further characterized in that the transverse area N1 of the supply flue is related to the transverse area of the discharge flue in accordance with the formula where T1 and T6 are the absolute temperatures, at the entrance end of the supply flue and the delivery end of the discharge flue, respectively.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0271084A2 (en) * 1986-12-11 1988-06-15 Nippondenso Co., Ltd. Refrigerant evaporator
US20160201519A1 (en) * 2015-01-14 2016-07-14 Ford Global Technologies, Llc Heat exchanger for a rankine cycle in a vehicle

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT192936B (en) * 1955-12-02 1957-11-11 Hans Dipl Ing Dr Techn Winter Branch system for gases, vapors or liquids
FR1396215A (en) * 1964-05-26 1965-04-16 Luwa Ag Collector for liquid or gaseous fluid applicable to a treatment apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT192936B (en) * 1955-12-02 1957-11-11 Hans Dipl Ing Dr Techn Winter Branch system for gases, vapors or liquids
FR1396215A (en) * 1964-05-26 1965-04-16 Luwa Ag Collector for liquid or gaseous fluid applicable to a treatment apparatus

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0271084A2 (en) * 1986-12-11 1988-06-15 Nippondenso Co., Ltd. Refrigerant evaporator
EP0271084A3 (en) * 1986-12-11 1989-08-09 Nippondenso Co. Ltd. Refrigerant evaporator
US20160201519A1 (en) * 2015-01-14 2016-07-14 Ford Global Technologies, Llc Heat exchanger for a rankine cycle in a vehicle
US9890666B2 (en) * 2015-01-14 2018-02-13 Ford Global Technologies, Llc Heat exchanger for a rankine cycle in a vehicle

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