US3223152A - Surface condenser - Google Patents

Description

Dec. 14, 1965 F. SCHULENBERG FIG.

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F. SCHULENBE RG SURFACE CONDENSER m m m Filed Dec. 27, 1962 Dec. 14, 1965 m m E United States Patent 3,223,152 SURFACE CONDENSER Franz Schulenberg, Boehum, Germany, assignor to Gea- Luftkuhler-Gesellschaft rn.b.H., Bochum, Germany Filed Dec. 27, 1962, Ser. No. 250,729 11 Claims. (Cl. 165-146) The present invention relates to surface condensers in general, and more particularly to a surface condenser for steam and similar vaporous media which is preferably cooled by atmospheric air. Still more particularly, the invention relates to a surface condenser which is especially suited for condensing steam by exchange of heat with positively circulated directed currents of air.

This application is a continuation-in-part of my application Serial No. 682,238, filed Sept. 5, 1957, now US. Patent No. 3,073,575.

It.is an important object of my invention to provide an apparatus which is capable of condensing large quantities of vaporous media per unit of time and which is constructed and assembled in such a way that, even though the medium to be condensed may be divided into two or more streams, condensation of all such streams occurs at the same rate of speed and is sufficiently uniform to insure that each stream will yield the same amount of condensate if the streams contain identical volumes of a vaporous medium, or that each stream will yield proportionally equal quantities of condensate if the streams contain different quantities of a vaporous medium.

Another object of the invention is to provide an improved system of tubular conductors in which large quantities of steam or another vaporous medium may be condensed in a simultaneous operation, whose operation is independent of temperatures prevailing in the surrounding atmosphere, which is equally useful for rapid condensation of a vaporous medium in cold as well as in moderate or hot climates, and which may be assembled of a large number of identically configurated parts so that it may be manufactured and assembled at reasonable cost.

A further object of my instant invention is to provide an air-cooled surface condenser which may be constructed and assembled in such a way that one or more of its sections may be shut off or reactivated to insure that the capacity of the condenser corresponds to the volume of the vaporous medium which must be condensed per unit of time.

Still another object of the invention is to provide a surface condenser of the above outlined characteristics which may be manufactured of a wide variety of readily available material and which may be constructed with a view to eliminate or to reduce undesirable effects of so-called boundary layers which normally hinder the exchange of heat between a vaporous medium and the coolant.

The surface condenser of the present invention differentiates from the apparatus which is protected by the claims of my aforementioned patent in that its condenser units (ihereinafter also called condenser elements) comprise one or more rows of elongated tubular conductors of different heat exchanging capacity whereas the patented apparatus achieves a similar result by regulating the rate of flow (i.e., the total amounts) of a vaporous medium through the individual conductors. Of course, it is also within the purview of my invention to construct a condenser element in such a way that its conductors receive different quantities of vaporous medium and are additionally constructed and/ or shaped in a manner to have different heat exchanging capacities.

With the above objects in view, the invention resides in the provision of a surface condenser which comprises means for producing one or more directed currents of coolant such as atmospheric air, at least one condenser unit including (in its elementary form) two elongated tubular conductors arranged in such a Way that one thereof is located downstream of the other as seen in the direction in which the coolant flows whereby the one conductor is brushed by coolant which has been heated y and whose cooling capacity has been reduced in response to exchange of heat with the other conductor, a source of steam or another vaporous medium con nected with the intake end of each conductor, and means for receiving condensate from the discharge end of each conductor.

In accordance with the present invention, the heat exchanging capacity of the one conductor is different from the heat exchanging capacity of the other conductor, and the arrangement is preferably such that the heat exchanging capacities of the conductors are selected with a view to insure that the temperature of condensate discharged by both conductors is at least approximately the same. Thus, the heat exchanging capacity of the one conductor is superior to the heat exchanging capacity of the other conductor. It can be said that the heat exchanging capacity of consecutive conductors, as seen in the direction of coolant flow, increases proportionally with the drop in cooling capacity of the coolant so that the temperature of condensate at the discharge ends of all of the conductors is at least approximately the same.

The heat exchanging capacities of the two conductors may differentiate from each other for a number of reasons, for example:

(a) Because the total area of heat exchanging surfaces on one of the conductors is different from the total area of heat exchanging surfaces on the other conductor;

(b) Because the thermal conductivity of the material of one of the conductors is different from the thermal conductivity of the material of the other conductor;

(c) Because the mass of one of the conductors is different from the mass of the other conductor; and/or (d) Because one of the conductors comprises means for reducing the effect of the boundary layer or because the boundary layer affecting means on one of the conductors is more effective than the boundary layer affect.- ing means on the other conductor.

In addition, two or more of the above-outlined possibilities may be resorted to simultaneously, and it is equally possible to take advantage of one, two or more such possibilities in a surface condenser of the type protected by my aforementioned patent wherein the tot-a1 amounts of vaporous medium admitted to one of the conductors per unit of time are different from the total amounts of vaporous medium admitted to the other conductor within the same period of time.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, W111 be best understood from the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal vertical section through a complete condenser plant as seen in the direction of arrows from the line II of FIG. 2;

FIG. 2 is a partial top plan view of and a partial horizontal section through the condenser plant as seen in the direction of arrows from the line II-II of FIG. 1;

FIG. 3 is an enlarged transverse vertical section through the air-cooled condensing part of the condenser plant as seen in the direction of arrows from the line III-III of FIG. 2;

FIG. 4 is a front elevational view of a condenser element which forms part of the condenser plant shown in FIGS. 1 and 2;

FIG. is a section through the condenser element as seen in the direction of arrows from the line VV of FIG. 4;

FIG. 6 is a fragmentary partly end elevational and partly sectional view of a modified condenser element which differentiates from the element of FIGS. 4 and 5 in that its conductors comprise radial ribs of different surface areas, the section of FIG. 6 being taken along the line VIVI of FIG. 7;

FIG. 7 is a transverse section as seen in the direction of arrows from the line VII-VII of FIG. 6;

FIG. 8 is a fragmentary partially end elevational and partially sectional view of a further condenser element wherein the masses of the conductors are different;

FIG. 9 is a transverse section through an additional con- 1 denser element wherein staggered groups of conductors comprise heat dissipating elements of different materials and wherein the ribs of such heat dissipating elements are of different thicknesses;

FIG. 10 is a fragmentary partially end elevational and partially sectional view of an additional condenser element wherein the groups of conductors comprise heat dissipating elements consisting of different materials but wherein the thickness of all of the ribs which form part of such heat dissipating elements is the same;

FIG. 11 is a similar fragmentary partly end elevational and partly sectional view of another condenser element wherein the groups of conductors comprise heat dissipating elements and pipes consisting of different materials;

FIG. 12 is a transverse section through a further condenser element wherein the rows of conductors are staggered with respect to each other and wherein the heat dissipating elements in such staggered rows of conductors consist of materials having different thermal characteristics;

FIG. 13 is a fragmentary front elevational view of another condenser element which comprises three groups of o'val pipes and wherein certain heat dissipating elements comprise specially formed projections which serve as a means for reducing the thickness of or for eliminating the boundary layer of insulating fluid which normally develops around the conductors;

FIG. 14 is a transverse section as seen in the direction of arrows from the line XIV-XIV of FIG. 13;

FIG. 15 is an end elevational view of the condenser element as seen in the direction of arrows from the line XVXV of FIG. 14;

FIG. 16 is a transverse section through another condenser element whose heat dissipating elements are formed with differently configurated and differently distributed projections; and

FIG. 17 is a side elevational view of another heat dissipating element whose rib is formed with projections at each of its sides.

Referring now in greater detail to the illustrated embodiments, and first to FIGS. 1 and 2, there is shown a condenser plant including a steam turbine 2 which drives an electric generator 3 or a like machine and which discharges spent steam through a conduit 1 leading to a pair of symmetrically arranged conduits 4 each of which branches off into a pair of smaller-diameter conduits 4a for delivering steam to four upright connecting conduits 5. The diameter of the conduits 1, 4, 4a are proportioned to each other in such a way that the speed at which steam flows therethrough is substantially the same, i.e., the combined crosssectional area of two conduits 4a equals the cross-sectional area of the respective conduit 4, and so forth. As shown in FIG. 1, the conduits 4, 4a are laid below the ground, and FIG. 2 illustrates that the upright connecting conduits 5 are substantially equidistant from each other. The upper end of each conduit 5 is connected with two coaxially arranged diverging steam distributing conduits 6, 6a, and each of these steam distributing conduits feeds steam into two series of condenser elements or units 7, 7a. The diameters of the conduits 6, 6a diminish preferably 4 gradually in a direction away from the respective connecting conduits 5 proportionally with the rate at which the conduits 6, 6a feed steam to the respective series of condenser elements 7, 7a.

FIG. 3 shows that the associated series of condenser elements 7, 7a are inclined with respect to each other so as to resemble a roof structure wherein the respective steam distributing conduit 6 is disposed at a level above and between the upper ends of the condenser elements. Thus, the condenser elements 7, 7a diverge downwardly and outwardly from the opposite sides of the respective conduit 6.

The lower ends of the series of condenser elements 7, 7a are respectively connected with condensate collecting conduits 8, 8a which are parallel with the steam distributing conduit-s 6, 6a. The arrangement is preferably such that the condenser elements 7, 7a which are connected to a common steam distributing conduit 6 or 6a form two sides of a substantially equilateral triangle (see particularly FIG. 3), and the space between each pair of condensate collecting conduits 8, 8a accommodates one or more means for producing directed currents of coolant. Such means preferably assume the form of propeller blowers 9 of comparatively large diameter which are disposed in horizontal planes at a level somewhat below the level of the condensate collecting conduits 8, 8a. FIG. 2 shows that three closely adjacent blOWers 9 may be arranged beneath each series of condenser elements 7, 7a and each blower is preferably provide-d with a separate drive motor 10 which may be adjusted to drive the respective blower at a higher or lower speed. Furthermore, it is often desirable to provide each blower with blades 9a whose angle of incidence may be adjusted in any suitable way not forming part of this invention so that each b'lower may be regulated independently of the other blowers to produce an air current of desired volume and/or speed. Condensate collected by conduits 8, 8a is conveyed underground (arrows Z) by conduit means SD shown in FIGS. 1 and 2.

FIG. 3 illustrates that each series of condenser elements 7, 7a is mounted above an elongated suction chamber 11 open at all sides to communicate with large suction apertures 12 through which the blowers 9 draw substantial quantities of atmospheric air, and such air is thereupon compelled to form an upwardly flowing directed current of cool-ant and to pass through the gaps between the condenser elements 7, 7a in order to exchange heat with steam which flows from the respective distributing conduit 6 or 61: toward the respective condensate collecting conduits 8, 8a. Currents of air created by the blowers 9 are indicated in FIG. 3 by arrows X, whereas the arrows Y (FIGS. 1 and 2) indicate the flow of steam through the conduits 4 and toward the condenser elements 7, 7a. Walls 12a which surround the condenser elements 7, 7a form a duct through which heated air flows into the atmosphere so that such heated air cannot return directly into the suction chambers 11. In other words, air which has already passed through the condenser must be thoroughly mixed with cooler atmospheric air before it can be recirculated through the chambers 11.

It is not always necessary to arrange the condenser elements 7, 7a in mutually inclined double series or rows since such condenser elements may be disposed in horizontal planes or in planes which are inc-lined through more or less than 60 degrees with respect to the planes of the blowers 9. However, :it is normally desirable that the surface condenser comprise several condenser elements 7 and/or 7a which are connected in parallel insofar as the flow of vaporous medium is concerned, and which are cooled by exchanging heat with one or more directed currents of air or another coolant. As a rule, the currents of coolant are produced and directed to flow in a predetermined path artificially by means of blowers or the like. Furthermore, and as will be explained in connection with FIGS. 4 and 5, each condenser element 7 or 7a should comprise at least two steam conveying conduits or pipes which are spaced from each other as seen in the direction of air flow and which are connected in parallel so that each thereof may receive a stream of steam or another vaporous medium from a common source.

Referring now to FIGS. 4 and 5, the-re is shown a condenser element or unit 7 comprising a distributor or header 18 of large cross-sectional area which is connected with the steam distributing conduit 6 by a hollow connector 20 so that steam admitted into the header 18 (arrows Y) may be divided into several rows of smaller streams each including three streams U U U which are caused to enter through the intake ends of three spaced but aligned parallel conduits or pipes 13, 14, 15 and to flow in a direction toward a condensate-collecting header 19 which communicates with one or more hollow connectors 21 serving as a means for admitting condensate into the collecting conduit 8. The connector 20 preferably extends substantially along the entire length of the header 18. The connector or connectors 21 may be replaced by a tubular member which resembles the connector 20. It will be noted that the axes of the pipes 13-15 shown in FIG. 5 are perpendicular to the direction of flow of cooling air current (arrows X), and that these pipes are equally spaced from each other in the direct-ion indicated by such arrows so that steam admitted into the intake end of the median pipe 14 exchanges heat with air which has been preheated by exchange of heat with steam admitted into the intake end of the front pipe 13, and that steam admitted into the intake end of the rear pipe 15 exchanges heat with air which has been heated first -by exchanging heat with steam passing through the front pipe 13 and thereupon with steam passing through the median pipe 14. In accordance with my invention, the condenser element 7 is constructed and assembled in such a way that the temperature of all of the fluid streams (be it condensate or gas) which are discharged through the discharge ends of the pipes and enter the header 19 is at least nearly the same irrespective of the fact that the three streams were caused to exchange heat with air currents whose temperature rises as they pass from the front pipe 13 to the median pipe 14 and finally toward and beyond the rear pipe 15.

FIG. 4 shows that the condenser element 7 comprises eight sets of pipes 13-15 (only the front pipes 13 are shown) and that the axes of all pipes 13, 14 or 15 are located in common planes which are perpendicular to the direction of air flow. In other words, steam admitted to the header 18 by the connector 20 is divided into twentyfour smaller streams each of which passes through a separate pipe, and the condensate which the streams of steam yield in the respective pipes is thereupon discharged into the second header 19 to be conveyed through the connector or connectors 21 and into the collecting conduit 8. The header 19 communicates with a further hollow connector 22 leading into an exhaust conduit 23 which leads to an air evacuating device 23a shown in FIGS. 1 and 2. This air evacuating device may assume the form of a so-called steam ejector pump and serves as a means for creating partial vacuum in the pipes 13, 14 and 15 and for thereby causing steam or another vaporous medium to flow through the condenser element 7. In addition, the device 23a withdraws air which remains in the header 19 upon evacuation of condensate into the collecting conduit 8.

It goes without saying that each condenser element 7 or 7a may be equipped with a separate air evacuating device 23a or that a single air evacuating device may be connected with two, more or all conductors, the latter modification having been shown in FIGS. 1 and 2. Of course, it is equally possible to omit the conduits 23 and the connectors 22 and to connect the air evacuating device or devices 23a directly to the condensate collecting conduits 8, 8a. The air evacuating device 23a of FIGS.

6 1 and 2 is assumed to maintain the internal spaces of the condenser elements 7, 7a at a pressure of about 0.05 atmosphere absolute pressure.

As clearly shown in FIGS. 1 to 5, the header 18 and the steam conduitry connected thereto together constitute a source of vaporous medium whose temperature is higher than the temperature of coolant. This source is connected to all of the pipes 13 to 15 so that the temperature of streams of vaporous medium entering these pipes is at least nearly the same.

In accordance with my invention, the condenser element or unit 7 comprises three difierent types of heat dissipating or heat transmitting elements 24, 25, 26 which are respectively mounted on and surround the pipes 13, 14 and 15. Each heat dissipating element comprises a sleeve and a circular or polygonal washer-like fin or rib 27. The diameters and the areas of all fins 27 are the same whereas the sleeves 28b of the heat dissipating elements 25 are shorter than the sleeves 28a of the heat dissipating elements 24 but longer than the sleeves 280 of the heat dissipating elements 26. In other words, the combined area of heat exchanging external surfaces of all heat dissipating elements 25 on any given median pipe 14 is greater than the combined area of heat exchanging external surfaces of all heat dissipating elements 24 on any given front pipe 13 but smaller than the combined area of heat exchanging external surfaces of all heat dissipating elements 26 on any given rear pipe 15. Consequently, the heat exchanging capacity of each steam conductor 14, 25 is less than the heat exchanging capacity of each steam conductor 15, 26 but greater than the heat exchanging capacity of each steam conductor 13, 26. The expression steam conductor has been chosen to denote a pipe 13, 14 or 15 and all such heat dissipating elements (24, 25 or 26) which are mounted on the respective pipe. Of course, each such steam conductor may be modified by omitting the pipe 13, 14 or 15 and by assembling the sleeves 28a, 28b or 280 in such a way that they form a fiuidtight tubular body. As clearly shown in FIG. 5, the sleeves 28a of coaxial heat dissipating elements 24 abut against the fins 27 of the adjacent heat dissipating elements 24 so that the sleeves 28a actually form a second pipe which surrounds the respective front pip 13. The mounting of heat dissipating elements 25, 26 on the respective median and rear pipes 14, 15 is analogous. FIG. 5 illustrates that, owing to such mounting of the heat dissipating elements, the distance T between a pair of adjacent ribs 27 on a median pipe 14 exceeds the distance T between a pair of adjacent ribs 27 on a rear pipe 15 but is less than the distance T between a pair of adjacent ribs 27 on a front pipe 13. In other words, the heat exchanging capacities of the three groups of steam conductors 13, 24; 14, 25; 15, 26 are different owing to the fact that each conductor 14, 25 comprises a larger number of ribs 27 than a conductor 13, 24 but a lesser number of ribs 27 than a conductor 15, 26. The heat exchanging capacities of the three groups of conductors are correlated in such a way that they are inversely proportional to the temperature of the air currents (arrows X), such temperature being measured along the exterior and in immediate proximity of the respective steam conductor. Thus, since the temperature of the air currents is lowest at the time such currents exchange heat with the steam conductors 13, 24, the heat exchanging capacity of these steam conductors is less than the heat exchanging capacity of the conductors 14, 25 which latter are contacted by and exchange heat with the air currents only at the time such currents were heated by exchanging heat with the steam conductors 13, 24. The same applies to the steam conductors 15, 26 which exchange heat with the air currents after the latter were heated to an elevated temperature by previous exchange of heat first with one or more conductors 13, 24 and thereupon with one or more conductors 14, 25. It is not difficult to select the heat exchanging capacities of the three groups of steam conductors in such a way that the temperature of condensate discharged by the median pipes 14 is the same as or approximates the temperature of condensate which is discharged from the pipes 13 or 15.

The diameters of the/pipes 13 are identical with the diameters of the pipes 14 and 15, and all pipes are of identical length and of identical cross-sectional configuration. In other words, the so-called hydraulic diameters of all pipes are the same whereby each pipe may be assumed to conduct identical quantities of steam per unit of time. In actual operation, the situation is normally somewhat different because, even if the diameters, the lengths and the cross-sections of all pipes are the same, the front pipes 13 will convey greater quantities of steam than the pipes 14 and 15. However, the difference is rather negligible so that one can say without exaggeration that the volume of steam conveyed through a front pipe 13 corresponds substantially to the volume of steam passing through a pipe 14 or 15, i.e. the differences are minor and, as a rule, require no special attention at the time one calculates the capacity of a condenser element.

The thickness of each rib or fin 27 and the wall thickness of each sleeve 28a, 28b or 28c is also the same. In addition, the finish of external surfaces on each of the heat dissipating elements 24, 25, 26 is also the same and all such elements are made of identical material, e.g., steel, aluminum or copper. In other words, the heat dissipating elements 24 differ from the heat dissipating elements 25 or 26 solely in the length of their sleeves whereas all remaining characteristics and dimensions of the heat dissipating elements 24-26 are the same. The ratio T :T :T is inversely proportional with the difference between the temperature of air currents brushing the conductors 13, 24; 14, 25; 15, 26 and the temperature of steam admitted to the pipes 13, 14, 15. Thus, since the difference between the temperature of air brushing the heat dissipating elements 26 and the temperature of steam passing through the rear pipes 15 is less than the difference between the temperature of air brushing the elements 25 and the temperature of steam passing through the median pipes 14, the heat exchanging capacity of a condutcor 15, 26 is greater than the heat exchanging capacity of a conductor 14, 25. The same applies to the heat exchanging capacities of the conductors 14, 25 and 13, 24.

In certain presently utilized surface condensers, the steam conductors in all groups are arranged in a manner similar to that shown in FIGS. 4 and 5 and each pipe receives the same quantity of steam. However, since the overall area of heat exchanging surfaces on all steam conductors is the same, condensation in the first group of conductors which come into contact with cooler air is more rapid than in the conductors which are located downstream of the first group of conductors. In other words, condensation in various conductors of the same condenser element or unit varies considerably so that all of the steam conveyed through the first group of conductors may be condensed at a point spaced from the condensate collecting conduit whereas steam passing through the other group or groups of conductors will be condensed immediately ahead of the condensate collecting conduit or it can happen that the condensation of steam flowing through certain conductors is only partial, i.e., that some steam may enter the condensate collecting conduit. It is obvious that the efficiency of such conventional condensate elements is rather low since the conductors which come into contact with cold air are too long whereas the length of certain other conductors is insufficient to insure full condensation of all of the steam passing therethrough. If a conductor is too long, the last portion thereof undergoes unnecessary undercooling. Such undercooling of steam conductors and of condensate is very undesirable in cold climates, particularly in heavy frost, because the condensate may be cooled below freezing point and the corresponding conductor or conductors are choked or sealed by ice plugs. Once such choking occurs, the next group of conductors is also cooled to a lower temperature which may be sufficiently low to cause freezing of condensate, i.e., even in the second group the boundary between the condensation range and the undercooling range moves further away from the condensate collecting conduit so that ice plugs developing in such next group of conductors prevent outflow of condensate and permit very cool air to undesirably reduce the temperature of condensate in the third, fourth etc. group, depending upon the number of group-wise arranged conductors in the condenser element. Such formation of ice plugs in one, two, three or even more groups of steam conductors is observable in conventional surface condensers at temperatures of about 20 C. It can happen that the surface condenser freezes up entirely or that its capacity is reduced to a very great extent.

The condenser element or unit 7 of FIGS. 4 and 5 avoids such drawbacks of just described conventional condenser elements merely by having the individual steam conductors arranged in such a way that the heat exchanging capacity of the conductors varies in the direction of coolant flow, i.e., the heat exchanging capacity of conductors which are brushed by coolest air is less than the heat exchanging capacity of conductors which are located downstream thereof, as seen in the direction of air flow, and so on, so that the heat exchanging capacity of the conductors preferably increases at the same rate at which the temperature of the air stream increases to insure that the formation of condensate is completed at or in immediate proximity of the condensate collecting conduit 8 or, better to say, in close proximity of the header 19 so that undercooling of condensate is very unlikely. If the temperature of atmospheric air varies considerably, the blowers 9 may be adjusted (by changing their rotational speed, i.e., by adjusting the motors 10, and/ or by changing the angle of incidence of the blades 9a) so that the circulation of very cool air is less pronounced than the circulation of air on warmer days. Consequently, subcooling of condensate and the formation of ice plugs in the conductors of my improved condenser element 7 is very unlikely 0r plainly impossible, and the condensation takes place by far better utilization of the available heatexchanging surfaces which is of advantage not only at low temperatures but also in warmer climates. Furthermore, the likelihood that some steam (particularly in conductors which are brushed by comparatively warm air currents) would enter the condensate collecting conduits is very remote so that the device 23a will not extract any steam from the system.

It will be readily understood that the condenser elements or units 7a are identical with the condenser element 7 of FIGS. 4 and 5 excepting that they discharge the condensate into collecting conduits 8a. By the same token, the condenser element 7 of FIGS. 4 and 5 is identical with certain other condenser elements 7 which are shown in FIG. 2 as receiving steam from conduits 6a. In other words, all condenser elements of the surface condenser shown in FIGS. 1 and 2 may be of identical construction. Of course, such identity of all condenser elements 7, 7a is not essential for proper operation of the surface condenser but is preferred because a so constructed apparatus may be manufactured and assembled at a cost which is less than the cost of a surface condenser wherein the condenser elements in one group would be different from the condenser elements in the other groups or wherein each group would contain two or more differently constructed or dimensioned condenser elements.

The condenser element or unit of FIGS. 4 and 5 may be modified in a number of ways without departing from the spirit of my invention. In its simplest form, the condenser element may comprise only two steam conductors, for example, a conductor 13, 24 and a conductor 14, 25 or 15, 26. Furthermore, the condenser element may comprise one or more rows of four, five or even more steam conductors, as viewed in the direction of arrows X in FIG. 5, even though it is normally impractical to form the condenser element with rows of more than five conductors. As a rule, and insofar as I am advised at this time, the condenser element preferably comprises one or more rows of three or four steam conductors. Of course, the number of rows of such conductors (eight such rows having been shown in FIG. 4) may be increased or reduced, depending on the desired capacity of the condenser element. I have found that, if the number of steam conductors in a row exceeds five, i.e., if the row of three conductors shown in FIG. 5 were replaced by a row of six, seven or more conductors, the sixth, seventh, etc. conductors come in contact with air currents which were preheated by exchange of heat with the first five conductors of the same row to such an extent that there is very little difference between the temperature of such additional conductors and the temperature of air, i.e., the cooling effect of air which was preheated five or more times is frequently negligible.

For example, if the difference between the temperature of steam entering a front pipe 13 and the mean temperature of air brushing the heat dissipating elements 24 is 40 C., if the difference between the temperature of steam entering a median pipe 14 and the mean temperature of air brushing the elements 25 is 30 C., and if the difference between the temperature of steam entering a rear pipe 15 and the mean temperature of air brushing the elements 26 is 23 C., the ratio of heat exchanging surfaces and capacities of conductors 13, 24; 14, 25; 15, 26 should be 1/40zl/ 30:1/23. In other words, the ratio of the temperature of steam in the header 18 to the mean temperature of air brushing the three groups of steam conductors should be inversely proportional with the ratio of the heat exchanging surfaces and heat exchanging capacities of such conductors. Such construction of steam conductors insures that the temperature of all streams of condensate entering the header 19 is substantially the same.

FIGS. 6 and 7 illustrate a modified condenser element or unit 107 which comprises six rows of steam conductors and wherein each such row comprises three steam conductors of different heat exchanging capacities. The pipes 113, 114, 115 of all six rows of steam conductors are connected directly to a steam admitting header 118. Each front pipe 113 is surrounded by a series of coaxial heat dissipating or heat transmitting elements 124 and each such element comprises a sleeve 128 and a substantially square rib or fin 127a. The heat dissipating or heat transmitting elements 125 on the median pipes 114 comprise sleeves 128 and rectangular ribs or fins 1271? whose area is greater than the area of the ribs 127a. Finally, the heat dissipating or heat transmitting elements 126 on the rear pipes 115 comprise sleeves 128 and ribs or fins 1270 whose area is greater than the area of the ribs 127b. Thus, the heat exchanging surface of each steam conductor 114, 125 is greater than the heat exchanging surface of a conductor 113, 124 but smaller than that of a conductor 115, 126. The axial length of all sleeves 128 is the same so that the difference in the heat exchanging capacities of the three groups of steam conductors is obtained by providing the elements 125 with ribs 127:) whose heat exchanging surfaces are greater than the heat exchanging surfaces of the ribs 127a but smaller than the heat exchanging surfaces of the ribs 1270. The diameters and the lengths of all pipes 113, 114, 115 are the same and the material of each steam conductor 114, 125 is the same as that of a steam conductor 113, 124 or 115, 126. The manner in which the header 118 receives steam from a distributing conduit and the manner in which the pipes 113, 114, 115 discharge condensate into a collecting header and thence into a collecting conduit is the same as described in connection with FIGS. 1 to 5. Steam admitted into the header 118 in the direction indicated by the arrow Y is divided into eighteen smaller streams, there being six streams flowing through the group of front pipes 113 (arrow U six streams flowing through the group of median pipes 114 (arrow U and six streams flowing through the group of rear pipes (arrow U The air currents flow in the direction indicated by arrows X.

It will be noted that, in contrast to the construction of FIGS. 4 and 5, the three groups of steam conductors in the condenser element or unit 107 have different heat exchanging surfaces not because their heat dissipating elements are formed with sleeves of different length but rather because they comprise ribs or fins of different areas. The end result is the same as in the condenser element 7, i.e., condensate flowing from the median pipes 114 has the same or nearly the same temperature as the condensate flowing from the pipes 113 or 115. The distance T between adjacent pairs of ribs 127a, 127b or 1270 is always the same, i.e., all sleeves 128 are of identical axial length. The wall thickness of all sleeves 128 is the same, and the same applies for the thicknesses of the ribs 127a, 127b, 1270.

It will be understood that similar results can be obtained if some or all of the ribs 127a, 127b, 1270 are replaced by ribs of circular, oval, triangular, square, hexagonal or other shape. In other words, the illustration of square ribs 127a and of rectangular ribs 127b, 1270 should not be construed in a limitative sense because similar results can be obtained with otherwise configurated ribs so long as such ribs insure that the heat exchanging surfaces of the corresponding heat dissipating elements are selected in such a way that the temperature of condensate discharged from all steam conductors is substantially the same.

It is equally possible to reduce the number of steam conductors in each group or to form the condenser element or unit 107 with rows which comprise two, four or more conductors.

The axes of all pipes 113, 114 or 115 are disposed in a common plane and are substantially perpendicular to the direction of air flow.

The condenser element or unit 207 of FIG. 8 comprises one or more rows of pipes 213, 214, 215 whose intake ends are connected to a header 218 so as to receive streams U U U of steam or another vaporous medium which enters the distributor 218 in a direction indicated by the arrow Y. In this embodiment of my invention, the ribs 227a, 227b, 2270 which respectively form part of three different heat dissipating or heat transmitting elements 224, 225, 226 are of identical outlines and consist of identical material (e.g., steel, aluminum or copper); however, the thickness D of each rib 227b exceeds the thickness D of a rib 227a but is less than the thickness D of a rib 2270. The same applies for the sleeves 228a, 228b, 2280 which consist of the same material and are of identical axial lengths; however, the wall thickness of each sleeve 22812 is greater than the wall thickness of a sleeve 228a but less than the wall thickness of a sleeve 2280. Consequently, the heat exchanging capacity of the conductor 214, 225 is greater than the heat exchanging capacity of the conductor 213, 224 but is less than that of the conductor 215, 226. The wall thicknesses of the heat dissipating elements 224, 225, 226 are again selected in such a way that the temperature of condensate discharged from the pipes 213, 214, 215 is at least approximately the same. The pipes 213-215 consist of the same material and their axial lengths and diameters are identical.

Of course, after looking at FIG. 8, one could say that the sleeves 22812 are shorter than the sleeves 228a but longer than the sleeves 2280. However, if one considers that the innermost portion of each rib 227a, 227b, 2270 forms part of the respective sleeve, then the sleeves may be said to be of identical lengths.

It can also be said that the heat exchanging surface of the conductor 214, 225 is identical with the heat exchanging surface of the conductors 213, 224 or 215, 226. Thus, the feature that the heat exchanging capacity of the conductor 214, 225 is greater than that of the conductor 213, 224 but less than that of the conductor 215, 226 is due to the fact that the mass of the conductor 214, 225 is greater than that of the conductor 213, 224 but less than the mass of the conductor 215, 226. In other words, instead of utilizing steam conductors with heat exchanging surfaces of different areas, one can achieve the same result by using steam conductors with different masses or volumes, the expression volumes being intended in this instance to denote the total mass of a pipe and of all heat dissipating elements which are mounted thereon.

The distance between the axis of the median pipe 214 on the one hand and the axes of the pipes 213, 215 on the other hand is the same, i.e., the pipes in the row which is illustrated in FIG. 8 are equidistant from each other. Of course, the condenser element 207 may comprise two or more rows of pipes 213-215 so that two or more pipes 213 form a front group of aligned pipes whose heat dissipating elements 224 are first to come into contact with cool air flowing in the direction indicated by arrows X, that two or more pipes 214 form a median group of aligned pipes which is located downstream of the front group, and that two or more pipes 215 form a rear group of pipes which is located downstream of the pipes 214, as viewed in'the direction of arrows X. Furthermore, the condenser element 207 may be modified by omitting one of the pipes shown in FIG. 8 or by adding one or more pipes in each row so that this condenser element may comprise say two, three or more rows of pipes wherein the number of pipes normally does not exceed five for the reasons explained hereinbefore. In this description, different steam conductors are being said to form rows which (in the embodiments of FIGS. 1 to 8) are disposed in comm-on planes, and two or more identical steam conductors (see FIG. 4 or 7) are said to be arranged in groups which, in the embodiments of FIGS. 1 to 8, are also arranged in common planes, such planes being preferably perpendicular to the direction of air flow.

The condenser element 207 is constructed with a view to take advantage of the fact that the transfer of heat from the interior of a thick-walled body to the surrounding atmosphere is greater than the transfer of heat from the interior of a thin-walled body. The thicker the ribs 22711-2270 and/or the walls of the sleeves 228a- 2280, the better will be the transfer of heat from a vaporous medium surrounded by such heat dissipating elements to the current of air which brushes the exterior of the heat dissipating elements. It will be readily understood that, at least in some instances, it is sufficient if only the wall thickness of the sleeves 228a2280 or of the ribs 227a-227c is different. When applied in the condenser element 207 of FIG. 8, this would mean that one could reduce the thickness of the ribs 2270 by simultaneously increasing the wall thickness of the sleeves 2280 so that the thickness of the ribs 2270 would approximate or be even less than that of the ribs 227]; or 227a. All that counts is that the thicknesses of the ribs and/ or the wall thicknesses of the sleeves be selected with a view to insure that the temperature of condensate which is discharged from the median pipe 214 is substantially the same as or identical with the temperature of condensate which is discharged from the pipe 213 or 215.

Referring to FIG. 9, there is shown a condenser element or unit 307 which comprises three groups of pipes 313, 314, 315 and each such group comprises seven pipes. In contrast to the construction of the condenser elements 7, 107 and 297, the group of front pipes 313 is not arranged in a common plane but rather in Zig-zag formation. Thus, and counting from the left-hand side of FIG. 9, all oddly numbered pipes 313 are disposed in a first plane which is preferably perpendicular to the direction of air flow (arrows X), and all evenly numbered pipes 313 are disposed in a second plane which is parallel with and is located downstream of the first place. The median pipes 314 and the rear pipes 315 are arranged in identical fashion. It will be noted that each front pipe 313 is aligned with a median pipe 314 and with a rear pipe 315, as viewed in the direction of arrows X, so that the pipes form seven rows of pipes with the median pipes 314 located upstream of the respective rear pipes 315 but downstream of the respective front pipes 313, as viewed in the direction of air flow.

Each front pipe 313 is surrounded by a series of heat dissipating or heat transmitting elements 324 having sleeves 328a of identical axial lengths and rectangular ribs 327a, such pipes and the heat dissipating elements 324 mounted thereon forming a group of seven steam conductors which may receive steam and which may discharge condensate in the same way as described in connection with FIGS. 4 and 5. The heat dissipating or heat transmitting elements 325 on the median pipes 314 comprise sleeves 32819 and rectangular ribs 327b whose configuration is the same as but whose thickness exceeds the thickness of the ribs 327a. The thickness of the ribs 3270 which together with the sleeves 3280 constitute heat dissipating or heat transmitting elements 326 for the rear ipes 315 is greater than the thickness of the ribs 327b.

Furthermore, the material of the heat dissipating elements 325 is a better thermal conductor than the material of the heat dissipating elements 324, and the material of the heat dissipating elements 326 is a better thermal conductor than the material of the heat dissipating elements 325. For example, the heat dissipating elements 324 may be made of steel, the heat dissipating elements 325 may consist of aluminum, and the heat dissipating elements 326 may consist of copper. Thus, the advantage that the temperature of condensate discharged from all of the pipes 313, 314, 315 is substantially the same is due to the combination of two features, namely, that the thickness of the ribs 32711 is greater than the thickness of the ribs 327a but less than the thickness of the ribs 3270, and also that the material of the ribs 327b (and preferably of the entire elements 325) is a better thermal conductor than the material of the ribs 327a but inferior to the material of the ribs 3270. Otherwise, the dimensioning of all of the steam conductors 313, 324; 314, 325; 315, 326 is the same and the pipes 313-315 may consist of identical material. The feature that the thermal conductivity of the material of the ribs 327a is less than the thermal conductivity of the material of the ribs 327b and that the thermal conductivity of the material of the ribs 327]) is less than the thermal conductivity of the material of the ribs 3270 is indicated in FIG. 9 on one of the ribs 327a by closely adjacent inclined lines 327a, on one of the ribs 32717 by a set of more widely spaced inclined line 32712, and on one of the ribs 3270 by a set of widely spaced inclined lines 3270'.

For example, the ratio of the thickness of the ribs 327a, 327b, 327a may but need not always be 3:425. Of course, and as will be explained hereinafter, it is equally possible to utilize ribs of identical thicknesses and to rely solely on different thermal conductivity of materials of which the ribs, the entire heat dissipating elements and/ or the pipes are made.

In the condenser element or unit 407 of FIG. 10, all of the heat dissipating or heat transmitting elements 424, 425, 426 and all of the pipes 413, 414, 415 are of identical configuration and of identical dimensions. However, the material of the heat dissipating elements 425 is a better conductor of heat than the material of the heat dissipating elements 424. Also, the material of the heat dissipating elements 426 is the best conductor of heat. For example, the heat dissipating elements 424 may be made of steel, the heat dissipating elements 425 may consist of aluminum, and the heat dissipating elements 426 may consist of copper. The hatching of the heat dissipating elements 425 is denser than the hatching of the heat dissipating elements 426 but less dense than the hatching of the heat dissipating elements 424 to indicate visually that the thermal conductivity of the steam conductor 414, 425 is superior to that of the conductor 413, 424 but inferior to that of the conductor 415, 426. The pipes 413415 consist of identical material and receive streams of steam (arrows U U U from a common header 418. The ribs 427a427c may be of circular, oval or polygonal shape and are integral with the respective sleeves 428a, 428b, 428a.

-A further embodiment of my invention which is so obvious that it requires no illustration comprises one or more rows of pipes which consist of different materials and heat dissipating elements of identical material. Another readily conceivable modification may comprise one or more rows of pipes made of materials having different heat conductivities and surrounded by heat dissipating elements of identical material but of different wall thicknesses so that the heat exchanging capacity of the front conductor or conductors will be less than the heat exchanging capacity of the conductor or conductors located downstream thereof.

In the condenser element or unit 507 of FIG. 11, the front pipe 513 and the heat dissipating or heat transmitting elements 524 consist of metallic material which is a comparatively poor conductor of heat when compared to the thermal conductivity of the material of the median pipe 514 and of the heat dissipating or heat transmitting elements 525, and which is an even poorer conductor of heat when compared with the thermal conductivity of the material of the pipe 515 and of the heat dissipating or heat transmitting elements 526. For example, the steam conductors 513, 524; 514, 525; 515, 526 may respectively consist of steel, aluminum and copper. Otherwise, the dimensions and all other characteristic features of all of the pipes 513-515 are the same, and this also applies for the heat dissipating elements 524-526. The pipes 513- 515 are equidistant from each other, and it will be readily understood that the condenser element 507 may comprise two or more rows of steam conductors which may be arranged in coplanar groups or in zig-Zag fashion as illustrated in FIG. 9, and the pipes 513515 receive streams of steam from a common header 518.

The condenser element or unit 607 of FIG. 12 comprises three groups of pipes 613, 614, 615 which may consist of steel. The front and the rear groups (as seen in the direction of arrows X) respectively comprise six coplanar pipes 613, 615, whereas the median group comprises merely five coplanar pipes 614 which are staggered with respect to the pipes 613, 615. The thermal conductivity of the heat dissipating or heat transmitting elements 624 on the front pipes 613 of the uppermost group of steam conductors, as viewed in FIG. 12, is poorer than the thermal conductivity of heat dissipating or heat transmitting elements 625 on the median pipes 614, and the thermal conductivity of the heat dissipating or heat transmitting elements 626 on the rear pipes 615 is superior to that of the heat dissipating elements 625. For example, the heat dissipating elements 624, 625, 626 may respectively consist of steel, aluminum and copper. Of course, many different variations are possible in the selection of materials for the heat dissipating elements 624 626, and this also applies for the parts shown in FIGS. 9 to 11; thus, it is possible to utilize various alloys of the aforementioned metals and of certain other metals as long as such alloys exhibit the desirable heat conducting characteristics.

The parts identified by numerals 641, 642 are bafiies which compel the currents of air flowing in the direction of arrows X to impinge against the heat dissipating elements 624-626 in this order, i.e., the currents of air are compelled to pass through the gaps 643 between the heat dissipating elements 624, thereupon through the gaps 644 between the heat dissipating elements 625, and finally through the gaps 645 between the rearmost heat dissipating elements 626 before such currents can mix with cooler atmosphericair. It will be noted that the configuration of all of the heat dissipating elements 624- 626 is the same and that the width of the gaps 643645 is also the same throughout the entire condenser element 607. In this embodiment of my invention, each front conductor 613, 624 is aligned with and forms a row with a rear conductor 615, 626 but is out of alignment with a median conductor 614, 625. An important advantage of such construction is that air currents passing through the gaps 643 are compelled to impinge squarely against the heat dissipating elements 625, and that air currents passing through the gaps 644 are also compelled to impinge squarely against the heat dissipating elements 626, i.e., contact between the air currents and the steam conductors is superior to that in the previously described condenser elements.

It goes without saying that the number of pipes in each of the three groups may be increased or reduced, and that one or more additional groups of staggered steam conductors may be added if necessary.

Referring to FIGS. 13, 14 and 15, there is shown a further condenser element or unit 707 which comprises nine parallel pipes of oval or elliptical cross section. The length, cross-sectional configuration and the material of all nine pipes is the same. As illustrated in FIG. 14, the condenser element 707 includes three front pipes 713 which are surrounded by heat dissipating or heat transmitting elements 724 each of which comprises a sleeve 728a and a smooth-surfaced rectangular rib or fin 727a; three pipes 714 surrounded by heat dissipating or heat transmitting elements 725 each of which includes a rib 727b and a sleeve 72%; and three pipes 715 surrounded by heat dissipating or heat transmitting elements 726 each of which comprises a sleeve 728s and a rib 7270. The front pipes 713 are coplanar and form a group whose plane is perpendicular to the direction of air flow (arrows X), and each front pipe 713 forms with a medium pipe 714 and with a rear pipe 715 a row coplanar pipes which are disposed in planes parallel with the direction of air flow. It is assumed that the heat dissipating elements 724726 are of identical configuration, of identical dimensions and of identical material, e.g., steel, aluminum, copper or an alloy of such metals. The spacing between all of the steam conductors 713, 724; 714, 725; 715, 726 is the same, and it is assumed that the pipes 713-715 receive a vaporous medium from a common header 718, see the arrows U U and U The longer axis of the elliptical outline of each pipe is parallel with the direction of air flow.

In order to insure that the temperature of condensate which is discharged from the front pipes 713 is at least substantially the same as the temperature of condensate discharged from a pipe 714 or 715, one side of each of the ribs 727b and 7270 is respectively provided with suitable projections or lugs 750B, 7500 which serve as a means for reducing the thickness of or for eliminating the socalled boundary layer of air or another coolant which is formed around the heat dissipating elements and which hinders the exchange of heat between the steam flowing through the pipes 713-715 and the surrounding air currents. In the embodiment of FIGS. 13 to 15, the projections 750B, 750C are formed by stamping or by a similar method in that each such projection assumes the form of a rectangular lug which is bent from the general plane of the respective rib and into a plane which is substantially perpendicular to the plane of the respective rib. As shown, the ribs 727a are without such projections so that the effect of boundary layer is felt more strongly on the heat dissipating elements 724 which are first to come into contact with currents of cooling air. The ribs 727b are formed with four symmetrically arranged projections 750B which are disposed in or close to the four corners of these ribs and are located in planes parallel with the direction of air flow so that such projections 750B tend toweaken the effect of the boundary layer and permit better exchange of heat between the steam flowing through the median pipes 714 and the currents of air which was preheated by contact with the heat dissipating elements 724. Each rib 7270 is formed with six projections 7500 which are similar to or identical with the projections 750B and which are. capable of weakening the effect of the boundary layer surrounding the heat dissipating elements 726 to such an extent that the exchange of heat between the steam flowing through the rear pipes 715 and atmospheric air which was preheated by contact with the heat dissipating elements 724, 725 is better than the exchange of heat between the air current and the steam conductors 713, 724 or 714, 725. The projections 750C on each of the ribs 727c are arranged in two rows each comprising three such projections, and it will be noted that all of the projections 750B, 7500 are disposed in such a way that they are not concealed by the pipes 713-715, as viewed in the direction of air flow. The feature that the influence of the boundary layer may be weakened or that such boundary layer may be eliminated is utilized in the condenser element 707 to insure that the exchange of heat between the conductors and the air currents improves at the same rate at which the temperature of the air currents rises to thereby insure that the ultimate effect of this condenser element will be the same as or similar to that of the previously described condenser elements. Of course, it goes without saying that the number of pipes 713-715 may be increased or reduced together with the number of heat dissipating elements, and that the projections 750B, 750C may be arranged in a number of other ways. For example, and as shown in FIG. 16 which illustrates a very simple condenser element or unit 807 having a single roW of steam conductors 813, 824; 814, 825; 815, 826, each heat dissipating or heat transmitting element may be provided with means for reducing the effect of or for eliminating the boundary layer. In this embodiment of my invention, each of the ribs 827 which together with the sleeves 828 constitute the heat dissipating elements 824 is provided with a single projection 850A which is parallel with the direction of air flow (arrow X) and which assumes the form of an elongated centrally located bead or corrugation. Each of the ribs 82711 which form part of the heat dissipatingelements 825 is integral with a sleeve 828b and is formed with three equidistant projections in the form of beads or corrugations 850B which are parallel with the projections 850A. The ribs 827a are integral with sleeves 8280 to form the heat dissipating elements 826 and each thereof is provided with five projections or beads 8500 which are parallel with the projections 850A, 850B. The pipes 813-815 are of circular cross section and consist of identical material, preferably but not necessarily of the same material as the heat dissipating elements 824-826. Thus, in the embodiment of FIG. 16, the boundary layer is influenced around each of the steam conductors so that the exchange of heat between streams of a vaporous medium and the surrounding air currents is very satisfactory immediately in the area around the front conductor 813, 824.

In the condenser elements 707 and 807, all of the ribs 727a-727c and 827a-827c are assumed to be equidistant from each other.

FIG. 17 illustrates a modified heat dissipating or heat transmitting element 926 which may be utilized in the previously described condenser elements, for example, in the element 707 or 807, and which comprises a sleeve 928a and a rib 9270, the latter having projections 950C in the form of ribs, beads or lugs provided at each of its sides to insure that the effect of the boundary layer is felt even less than if such projections were provided only at the one or the other side of the rib 927c.

The various projections on the ribs 72712-7270, 827a- 8270 and 9270 create turbulence around the respective heat dissipating elements, and such turbulence affects the boundary layer which latter forms some sort of an insulating coat or cushion around the heat dissipating elements and tends to prevent direct contact of moving coolant with the material of these elements.

The effect of the projections 750B-750C, 850A-850C and 950C upon the boundary layer may be explained by the theory that such projections cause the aforementioned vibrations or burbulences and/or that the projections provide additional edges which are in the path of the air currents so that the currents penetrate into and reduce the thickness of or eliminate the insulating cushion or coat of fluid which forms the boundary layer.

It has been found that the projections of the type shown in FIGS. 13 to 15 are very satisfactory in actual use and that such projections may be formed at very low cost. In addition, such projections do not undesirably affect the flow of air currents, i.e., they do not overly increase the resistance which the steam conductors offer to the flow of coolant in the direction of arrows X.

Finally, it should be mentioned that the results achieved with the condenser elements or units of FIGS. 4-16 may be obtained by utilizing condenser elements that embody a combination of features which distinguish the condenser elements 7, 107, 207, 307, 407, 507, 607, 707 and 807 from each other. For example, it will be readily understood that each of the condenser elements shown in FIGS. 4-12 may be provided with means which reduce the effect of or which eliminate the influence of the boundary layer; that the condenser elements of FIGS. 4-12 and 16 may comprise steam conducting pipes of elliptical, oval or polygonal cross-sectional outline; that the groups of conductors shown in FIGS. 13 to 15 may consist of different materials or that certain component parts (such as the heat dissipating elements or the pipes) of these conductors may consist of different materials; that the conductors of FIGS. 4 to 11 and 13 to 16 may be staggered in the same way as or in a manner similar to that shown in FIG. 12; that the ribs may form integral parts of the steam conducting pipes, i.e., that the sleeves of the heat dissipating elements may be omitted; that the configuration of ribs in each group of steam conductors may be different; and many other modifications which are too numerous to mention and which will readily occur to men skilled in the art upon perusal of the preceding disclosure. All that counts is to assemble the condenser elements in such a way that each thereof comprises at, least two conductors one of which is located downsteam of the other thereof, as viewed in the direction in which air or another coolant flows and that the heat exchanging capacities of the conductors are sufficiently different to insure that the temperature of condensate discharged from their pipes is at least nearly the same.

1 also wish to mention that it is possible to provide a condenser element or unit which embodies the features of the present invention and the features of my aforementioned patent, for example, by providing means for regulating the rate of flow of a vaporous medium through the pipes, i.e., for varying the total' amounts of vaporous medium in consecutive pipes as seen in the direction of the flow of coolant. in FIG. 11 which shows that the intake end of the pipe 514 may accommodate a removable annular throttling member 560 (shown in phantom lines) which insures that the rate of inflow of vaporous medium into the median pipe 514 is less than the rate of inflow of vaporous medium into the front pipe 513. The intake end of the rear pipe 515 accommodates another removable throttling member 561 which reduces the rate of inflow of various medium into this pipe to below the rate at which such medium may flow into the median pipe 514. Thus, in addition to utilizing conductors of different materials, the condenser element 507 may be constructed in such a way that the rate of flow of vaporous media through different groups of its pipes is different, i.e., that the rate of flow diminishes in the direction of cool- This is illustrated schematically 17 ant flow. Identical. results can be obtained byutilizing pipes of different diameters.

Similar or otherwise constructed throttling means may be used in other condenser elements, if desired. Such throttling means may also be used for uniformly reducing the rate of inflow of steam into each of the pipes in all of the: illustrated. condenser elements in the event that the temperature of coolant drops below such temperature at which the steam condenser of my invention operates with optimum efficiency. However, whenever a condenser element is constructed in a manner to combine two or more features of the present invention or one or more features of the present invention and the feature disclosed in the aforementioned patent, care must be exercised that the heat exchanging capacity of consecutive steam conductors preferably increases and that the total amounts of vaporous medium entering the consecutive conductors preferably decrease at the same rate at which the temperature of coolant coming in contact with the respective conductors increases (i.e., proportionally with the drop in cooling capacity of the coolant) to make sure that the temperature of condensate at the discharge ends of all of the pipes is at least nearly the same.

The following specific example is being given merely for better understanding of the invention and should not be construed in a restrictive sense:

It is assumed that the temperature of the air currents is. 20 C.- and that the surface condenser of my invention comprises one or more condenser units constructed in a manner as shown in FIGS. 4 and 5. The temperature of steam entering the header 18 is assumed to be 40 C.. The air coming into contact with the heat dissipating elements 24 of the front group of steam conductors 13, 24 is already heated to 15 C. at the time it reaches the front group so that the total difference between the temperature of steam entering the pipes 13 and the temperature of surrounding air is 55 C. The air currents reaching the second group of steam conductors 14, 25 are already heated to 6.5 C. so that the total difference between the temperature of steam entering the pipes 14 and the temperature of air surrounding the heat dissipating elements 25 is 46.5 C. At the time the air currents reach the third or rear group of steam conductors 15, 26 their temperature rises to 0.5 C, so that the total difference between the temperature of steam entering the pipes 15 and the temperature of air brushing theheat dissipating elements 26 is 40.5" C. Conse quently, the heat exchanging capacities of the conductors 13, 24; 14, 25; 15, 26 must be proportioned as 40.5 246.5 :55, i.e., the ratio of the heat exchanging capacity of a steam conductor 13, 24 to the heat exchanging capacity of a conductor 14, 25 must be inversely proportional to the ratio of the differential between the temperature of steam entering a pipe 13 and the temperature of surrounding air and the differential between the temperature of steam entering the pipe 14 and the temperature of surrounding air.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for vari ous applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a surface condenser, in combination, means for producing a directed current of coolant; a source of vaporous medium whose temperature is higher than the temperature of coolant so that the medium yields condensate in response to exchange of heat with the coolant; and a condenser unit including a pair of tubular conductors each having an intake end connected with said source and a condensate-discharging second end, said conductors being disposed in the path of and substantially transversely to the direction of the flow of coolant so that coolant brushing said conductors tends to form around said conductors astagnant boundary layer which hinders the exchange of heat between the medium and the flowing coolant, one' of said conductors being located upstream of the other conductor as seen in the direction of flow of the coolant so that coolant brushing said one conductor is heated and its cooling capacity decreases prior to brushing said other conductor, said other conductor comprising means for reducing the effect of the boundary layer suflicien'tly to insure that the heat exchanging capacity of said other conductor is superior to the heat'exchanging capacity of said one conductor proportionally with the drop in cooling capacity of the coolant whereby the temperature of condensate at both said second ends is at least nearly the same.

2. A combination as set forth in claim 1, wherein the means for reducing the effect of said boundary layer comprises external projections on said other conductor.

3. A combination as set forth in claim 2, wherein each of said conductors comprises an elongated pipe and radially arranged ribs provided around the respective pipe, said projections forming part of the ribs on the pipe of said other conductor.

4. A combination as set forth in claim 3, wherein said projections are lugs disposed in planes substantially paral lel with the direction of the flow of coolant.

5. A combination as set forth in claim 3, wherein each of said ribs has a first side and a second side and" wherein said projections are provided along at least one side of each rib.

6. A combination as set forth in claim 1, wherein each of said conductors comprises an elongated pipe and a plurality of heat transmitting elements surrounding. the

respective pipe, each of said heat transmitting elements comprising a rib disposed in a plane substantially perpendicular to the axis of the respective pipe and the means for reducing the effect of the boundary layer around said other conductor comprising a plurality of elongated cor rugations provided on the ribs in the heat transmitting elements of said other conductor, said corrugations being substantially parallel with the direction of the flow of coolant.

7. In a surface condenser, in combination, means for producing a directed current of coolant; a source of vaporous medium whose temperature is higher than the temperature of coolant so that the medium yields condensate in response to exchange of heat with the coolant; and a condenser unit including a pair of tubular conductors each having an intake end connected with said source and a condensate-discharging second end, said conductors being disposed in the path of and substantially transversely to the direction of the flow of coolant so that coolant brushingsaid conductors tends to form around said conductors a stagnant boundary layer which hinders the exchange of heat between the medium and the flowing coolant, one of said conductors being located upstream of the other conductor as seen in the direction of flow of the coolant so that coolant brushing said one conductor is heated and its cooling capacity decreases prior to brushing said other conductor, each of said conductors comprising means for reducing the effect of' the respective boundary layer and the effect reducing means of said other conductor being sufficiently superior to the effect reducing means of said one conductor to insure that the heat exchanging capacity of said other conductor is greater than the heat exchanging capacity of said one conductor in proportion with the drop in cooling capacity of the coolant whereby the temperature of condensate at both said second ends is at least nearly the same.

8. In a surface condenser, in combination, means for producing a directed current of coolant; a source of vaporous medium whose temperature is higher than the temperature of coolant so that the medium yields condensate in response to exchange of heat with the coolant; and a condenser unit including a pair of tubular conductors each having an intake end connected with said source and a condensate-discharging second end, said conductors being disposed in the path of and substantially transversely to the direction of the flow of coolant so that coolant brushing said conductors tends to form around said conductors a stagnant boundary layer which hinders the exchange of heat between the medium and the flowing coolant, one of said conductors being located upstream of the other conductor as seen in the direction of flow of the coolant so that coolant brushing said one conductor is heated and its cooling capacity decreases prior to brushing said other conductor, said other conductor comprising means for reducing the effect of the boundary layer and the total area of its external surfaces being greater than the total area of external surfaces on said one conductor to insure, in combination with a reduction in the effect of the boundary layer, that the heat exchanging capacity of said other conductor is superior to the heat exchanging capacity of said one conductor proportionally with the drop in cooling capacity of the coolant whereby the temperature of condensate at both said second ends is at least nearly the same.

9. In a surface condenser, in combination, means for producing a directed current of coolant; a source of vaporous medium whose temperature is higher than the temperature of coolant so that the medium yields condensate in response to exchange of heat with the coolant; and a condenser unit including a pair of tubular conductors each having an intake end connected with said source and a condensate-discharging second end, said conductors being disposed in the path of and substantially transversely to the direction of the flow of coolant so that coolant brushing said conductors tends to form around said conductors a stagnant boundary layer which hinders the exchange of heat between the medium and the flowing coolant, one of said conductors being located upstream of the other conductor as seen in the direction of flow of the coolant so that coolant brushing said one conductor is heated and its cooling capacity decreases prior to brushing said other conductor, said other conductor comprising means for reducing the effect of the boundary layer and the thermal conductivity of the material of said other conductor being greater than the thermal conductivity of the material of said one conductor to insure, in combination with a reduction in the effect of the boundary layer, that the heat exchanging capacity of said other conductor is superior to the heat exchanging capacity of said one conductor proportionally with the drop in cooling capacity of the coolant whereby the temperature of condensate at both said second ends is at least nearly the same.

10. In a surface condenser, in combination, means for producing a directed current of coolant; a source of vaporous medium whose temperature is higher than the temperature of coolant so that the medium yields condensate in response to exchange of heat with the coolant; and a condenser unit including a pair of tubular conductors each having an intake end connected with said source and a condensate-discharging second end, said conductors being disposed in the pa'th'of and substantially transversely to the direction of the flow of' coolant so that coolant brushing said conductors tends to form around said conductors a stagnant boundary layer which hinders the exchange of heat between the medium and the flowing coolant, one of said conductors being located upstream of the other conductor as seen'in the direction of flow of the coolant so that coolant brushing said one conductor is heated and its cooling capacity decreases prior to brushing said other conductor, said other conductor comprising means for reducing the effect of the boundary layer and the mass of said other conductor being different from the mass of said one conductor to insure, in combination with a reduction in the effect of the boundary layer, that the heat exchanging capacity of said other conductor is superior to the heat exchanging capacity of said one conductor proportionally with the drop in cooling capacity of the coolant whereby the temperature of condensate at both said second ends is at least nearly the same.

11. In a surface condenser, in combination, means for producing a directed current of coolant; a source of vaporous medium whose temperature is higher than the temperature of coolant so that the medium yields condensate in response to'exchange of heat with the coolant; and a condenser unit including a pair of tubular conductors each having an intake end connected with said source and a condensate-discharging second end, said conductors being disposed in the path of and substantially transversely to the direction of the flow of coolant so that coolant brushing said conductors tends to form around said conductors a stagnant boundary layer which hinders the exchange of heat between the medium and the flowing coolant, one of said conductors being located upstream of the other conductor as seen in the direction of flow of the coolant so that coolant brushing said one conductor is heated and its cooling capacity decreases prior to brushing said other conductor, said other conductor comprising means for reducing the effect of the boundary layer and the total area of its external surfaces being greater than the total area of external surfaces on said one conductor and the thermal conductivity of its material being greater than the thermal conduc tivity of the material of said one conductor to insure, in combination with a reduction in the effect of the boundary layer and with an increase in total area of external surfaces on the other conductor, that the heat exchanging capacity of said other conductor is superior to the heat exchanging capacity of said one conductor proportionally with the drop in cooling capacity of the coolant whereby the temperature of condensate at both said second ends is at least nearly the same.

References Cited by the Examiner UNITED STATES PATENTS 1,380,460 6/1921 Bancel 146 1,524,520 1/1-925 Junkers 165146 1,911,522 5/1933 McIntyre 165-146 1,974,876 9/1934 Schack l65146 2,107,478 2/1938 Happel 165146 ROBERT A. OLEARY, Primary Examiner.

KENNETH W. SPRAGUE, CHARLES SUKALO,

Examiners.

Claims (1)

1. IN A SURFACE CONDENSER, IN COMBINATION, MEANS FOR PRODUCING A DIRECTED CURRENT OF COOLANT; A SOURCE OF VAPOROUS MEDIUM WHOSE TEMPERATURE IS HIGHER THAN THE TEMPERATRE OF COOLANT SO THAT THE MEDIUM YIELDS CONDENSATE IN RESPONSE TO EXCHANGE OF HEAT WITH THE COOLANT; AND A CONDENSER UNIT INCLUDING A PAIR OF TUBULAR CONDUCTORS EACH HAVING AN INTAKE END CONNECTED WITH SAID SOURCE AND A CONDENSATE-DISCHARGING SECOND END, SAID CONDUCTORS BEING DISPOSED IN THE PATH OF AND SUBSTANTIALLY TRANSVERSELY TO THE DIRECTION OF THE FLOW OF COOLANT SO THAT COOLANT BRUSHING SAID CONDUCTORS TENDS TO FORM AROUND SAID CONDUCTORS A STAGNANT BOUNDARY LAYER WHICH HINDERS THE EXCHANGE OF HEAT BETWEEN THE MEDIUM AND THE FLOWING COOLANT, ONE OF SAID CONDUCTORS BEING LOCATED UPSTREAM OF THE OTHER CONDUCTOR AS SEEN IN THE DIRECTION OF FLOW OF THE COOLANT SO THAT COOLANT BRUSHING SAID ONE CONDUCTOR IS HEATED AND ITS COOLING CAPACITY DECREASES PRIOR TO BRUSHING SAID OTHER CONDUCTOR, SAID OTHER CONDUCTOR COMPRISING MEANS FOR REDUCING THE EFFECT OF THE BOUNDARY LAYER SUFFICIENTLY TO INSURE THAT THE HEAT EXCHANGING CAPACITY OF SAID OTHER CONDUCTOR IS SUPERIOR TO THE HEAT EXCHANGING CAPACITY OF SAID ONE CONDUCTOR PROPORTIONALLY WITH THE DROP IN COOLING CAPACITY OF THE COOLANT WHEREBY THE TEMPERATURE OF CONDENSATE AT BOTH SAID SECOND ENDS IS AT LEAST NEARLY THE SAME.

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