US 3148511 A
Description (OCR text may contain errors)
Sept. 15, 1964 l s. K. GABLE HEAT EXCHANGE APPARATUS Filed OOb. 1, 1962 FIG. l
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United States Patent F 3,148,511 HEAT EXCHANGE APPARATUS Gerald K. Gable, North Syracuse, N.Y., assignor to Carrier Corporation, Syracuse, N .Y., a corporation of Delaware Filed Oct. 1, 1962, Ser. No. 227,440 6 Claims. (Ci. 62-3) This invention relates to heat transfer surfaces, more particularly to means for improving the efficiency of heat exchange via a heat transfer surface by extending the effective area of the surface, and simultaneously implementing condensate drainage from the surface. The improved heat transfer surface is of particular use in situations where condensation is likely to take place on the heat transfer surface.
A variety of situations exist in which a heat transfer surface is utilized under circumstances where condensation occurs upon the surface. As is apparent, this condensation on the heat transfer surface interferes with heat transfer efficiency in that the condensate acts to insulate the surface. Thus in an air conditioning installation, under circumstances of relatively high humidity in the area in heat exchange relationship with the heat absorbing elements of the air conditioner, condensation will occur on the heat exchange surface of the heat absorbing elements with a resultant decrease in heat transfer efficiency.
Conventional modes of increasing the effectiveness of a heat transfer surface as utilized in air conditioning installations include the applications of fins to the heat transfer surface so as to increase the effective area thereof. Where these fins extend in a horizontal plane, the moisture condensed out of the air accumulates on the horizontally extending ns decreasing the effectiveness of heat exchange between the fins and the air moving thereover, and similarly reducing the cross-sectional area of the air flow path between the fins. There are a number of installations where horizontally extending fins are required due to the geometry of the heat exchanger structure. Thus, where the ns are provided on a vertical plate member such as is utilized in thermoelectric panels, with air fiow paths moving horizontally the fins must extend horizontally, and problems of condensate accumulation arise.
It is with the above problems and desiderata in mind that the present means have been evolved, means including both method and apparatus providing for an extension of effective heat transfer surface on a heat exchanger by the use of fins so as to obtain desired heat exchange efficiency, efficient air fiow with respect to the heat exchange surface, and drainage of condensate from the fin surface.
It is accordingly an object of this invention to provide an improved 1in arrangement for extending the effective heat transfer area of a heat exchange surface.
Another important object of the invention is to provide a n arrangement producing desired heat transfer effects from a heat exchange surface and permitting ready drainage of any accumulating condensate.
It is also an object of this invention to eliminate the problems arising from condensate accumulation on the fins of a heat transfer surface.
It is a further important object of this invention to provide a novel fin structure implementing drainage of condensate from a heat exchange surface in conjunction with which said n structure is employed.
A further object of the invention is to provide a drainage implementing fin structure which may readily be combined with a conventional fin structure to obtain desired heat exchange efficiency and condensate drainage.
3?,l485fl Patented Sept. 15., 1964 It is an additional object of this invention to provide an improved heat transfer surface particularly suitable for use with thermoelectric structures employed to cool an air stream by the use of the Peltier effect.
These and other objects of the invention which will become hereafter apparent are attained by provision of a novel fin structure arrangement in which a plurality of spaced conducting rods are extended from the primary heat exchange surface. These rod members are of a heat conducting material such as copper or the like, and are provided with fins arranged about the periphery of the rod so that the heat of the heat exchange surface is conducted via the rods and the surface extending fins of the rods to the medium in which the rods and ns are arranged. This novel fin structure which comprises a combination of a rod and a fin permit orientation of the fn in a vertical plane so that condensate accumulations on either the rods or the fins may readily be drained. The conventional plate iin structure normally employed to extend the effective heat transfer surface of a heat exchanger member may be combined with the novel finned rod so that the desired heat exchange efficiency of the conventional plate fin may be utilized in combination with the drainage effects of the finned rod to obtain desired heat exchange effects, air moving effects, and condensate drainage.
An important feature of the invention resides in the novel finned rods which implement condensate drainage.
Another feature of the invention resides in the cornbination of these finned rods with the plate fins to obtain desired temperature drops over the area covered by the plate fins, and a continuance of temperature drops in the area covered by the nned rods along with condensate drainage at the area of the heat exchanger where condensation first begins to accumulate.
An additional feature of the invention resides in the fact that normal air movement over the plate fins will aid in directing any condensate forming on the plate fins towards the condensate draining finned rods.
The specific details of a preferred embodiment of the invention will be made most manifest and particularly pointed out in clear, concise and exact terms in conjunction with the accompanying drawings, wherein:
FIGURE 1 is a perspective view with parts broken away of a thermoelectric heat exchanger utilized to effect air cooling and employing the novel fin arrangement of the instant invention; and
FIGURE 2 is a fragmentary cross-sectional view along lines II-II of FIGURE l.
Referring now more particularly to the drawings, like' numerals in the various figures will be taken to designate like parts.
As best seen in FIGURE 1, a heat exchanger 10 is shown, which in this instance happens to be a thermoelectric air cooler, but as will be apparent to those skilled in the art, the principles of this invention may readily be embodied in conjunction with a variety of other types of heat exchange equipment.
In the air cooling heat exchanger 10 of FIGURE 1 a thermoelectric panel 15 forms the core of the heat exchanger. Panel 15 forms no part of this invention and is of the type conventionally formed of thermoelectric couples fabricated from P-type and N-type semi-conductor materials joined by a conductor strap 16. A terminal cover and air deflecting vane 17 is arranged at opposite ends of the panel as viewed in FIGURE 1. Deflecting vane 17 acts to guide the air stream to the fins on opposite sides of the panel. An upper water header Z0 and a lower water header 21 are provided at the top and bottom respectively of the heat exchanger so that cooling water may be directed through inlet pipes 20 into heat exchange relationship with the heat dissipating junctions of the thermoelectric panel 15 and be drained from header 21 through outlet pipes 21'. A heat exchange plate member 25 forming a primary heat transfer surface is arranged in heat exchange relationship with the straps 16 forming heat absorbing cold junctions of thermoelectric panel. As seen in the drawing, the heat exchanger here employed is symmetrical about a vertical plane, with the heat absorbing heat exchange plate members 25 being arranged one on each side of the structure, so that cooling may be effected from either side of the device.
The front side of the structure as viewed in FIGURE l will be described, but it will be understood that the description is applicable to the obverse side of the FIG- URE 1 structure.
Arranged on the left-hand side of heat exchange surface 25 which will form the upstream portion of the heat exchanger are conventional plate fins 27. Platevlins 27 are formed of a material of high heat conducting capacity such as aluminum, copper, or the like material. The plate fins in the illustration are fabricated of a sheet material formed with a plurality of crimps 28 which serve the twofold purpose of increasing the strength of the lin structure and permitting an increase in surface area of the material of the fin per unit of surface area of the heat exchange plate 25 over which said fins are arranged. These conventional plate fins are arranged over the upstream surface of heat exchange plate 25 (to the left in the drawing) and extend in a horizontal plane implementing the movement of air along the heat exchanger surface.
At the downstream end of the heat exchanger, the novel finned rods 29 are arranged. Finned rods 29 as best seen in FIGURE 2 comprises a plurality of spaced vertically extending crimped plate members 30 formed with stiffening ribs 31 as best seen in FIGURE 1. The plate members 30 of finned rods 29 are arranged in a plane parallel to that of heat exchanger plate 25 and perpendicular to that of plate fins 27. The plate members 30 are formed of a material similar to that of plate fins 27 such as copper, aluminum, or the like. Extending through the plate members 30 at spaced intervals, and in heat exchange relationship with and secured to heat exchange plate 25 are projections in the form of pins or rods 32 of a high heat conductivity material such as copper or the like. Appropriate solder joints 33 are suitably utilized for joining the rods to the plate members 30 and for joining the bars to the heat exchange plate 25 as best seen in FIGURE 2.
The aforedescribed improved heat transfer surface may be employed in conjunction with a variety of different types of heat exchangers as will be apparent to those skilled in the art, and as heretofore noted. In the illustrated embodiment of the invention, the novel heat transfer surfaces are shown and described in conjunction with a thermoelectric air cooler in which the heat dissipating junctions of a thermoelectric panel are arranged for water cooling.
The heat exchanger 10 as shown in FIGURE 1, and above described, is formed with two thermoelectric panels arranged so that their heat absorbing junctions face outwardly. The heat dissipating junctions of thermoelectric panels 15 are arranged for water cooling by the space between opposed plates serving as a water jacket sandwiched between the two thermoelectric panels.
In use, the novel heat exchanger 10 is arranged so that the air to be cooled passes over the surface of the heat exchanger in a direction from left to right as viewed in FIGURE 1. Air ow is established over the surface in any conventional fashion, due to natural air currents, or artificially by means of fans or the like.
The heat exchanger is set into operation by appropriately energizing the heat pumping components of the panel, in this case by directing current flow through the thermoelectric elements, and the resulting heat pumping effects will reduce the temperature of heat exchange plates 25. When heat exchange plates 25 reach a temperature below that of the air passing over the heat exchanger 10, heat is absorbed from this air. As the air stream progresses over the surface of the heat exchanger 1f) it is reduced in temperature so that the air at the upstream side of the heat exchanger (to the left in FIGURE 1) is at a higher temperature than the air at the down stream side (to the right in FIGURE 1).
Desired design conditions are such that the temperature of the air at the end of the run of plate fins 27 will approach the dew point temperature of the air. Under these optimum design conditions condensation will first begin to form when the air stream enters the section containing the nned rods 29. Thus any condensate forming will be drained downwardly where it may either be collected or dissipated.
Since optimum design conditions do not always prevail, there is, of course, the possibility that under conditions of high humidity the dew point temperature will occur before the air stream reaches the novel condensate draining finned rods 29. Under these circumstances, condensate will form on the surface of the plate fins 27. However, the condensate will, in most instances, be blown along by the air stream until it reaches the novel finned rods 29, whence it may be drained.
It is thus seen that a novel heat transfer surface has been provided in which the heat transfer efficiency of the plate fin may be utilized to obtain rapid and efficient cooling of an air stream, and the drainage benefits of a novel finned rod structure may be utilized for condensate dissipation once the air has attained desired temperature levels, and dehumidification with its resultant condensate accumulation results.
The above disclosure has been given by way of illustration and elucidation, and not by way of limitation, and it is desired to protect all embodiments of the herein disclosed inventive concept within the scope of the appended claims.
1. An air cooler comprising: a thermoelectric panel; heat dissipating junctions on said panel in heat exchange relationship with cooling water; a heat exchange plate member in heat transfer relationship between the air to be cooled and the heat absorbing junctions of said panel; plate fins on said panel contacting the air to be cooled as it first commences flow over the heat exchange plate member, said plate fins extending in the direction of flow of the air; rods extending from said plate member downstream of said plate fins; and tins on said rod extending in a direction other than the horizontal, whereby condensate will be drained.
2. Means for effecting heat transfer between a heat exchanger and a gaseous medium flowing over the heat exchanger from an upstream point to a downstream point, said means comprising: primary heat conducting surface means on said heat exchanger; upstream fin means on said primary surface means in heat exchange relationship with said primary surface means and the gaseous medium as the gaseous medium first commences flow over the heat exchanger, said upstream fin means extending in a plan parallel to the direction of flow of the gaseous medium; and downstream fin means in heat exchange relationship with said primary heat conducting surface means and the gaseous medium, said downstream n means extending in a plane other than the horizontal whereby condensate will be drained.
3. Means for effecting heat transfer as in claim 2 in which projecting means extend from said primary heat conducting surface means through said downstream fin means in heat exchange relationship with said surface means and said fin means.
4. Means for effecting heat transfer as in claim 2 in which said fin means are formed with reinforcing rib means.
5. A heat transfer surface for effecting heat exchange between a relatively cold coolant and a flowing relatively warmer gaseous medium with the ow of heat from the gaseous medium produced by said heat exchange resulting in condensate formation on the heat transfer surface, said surface comprising: a primary heat conducting surface in heat exchange relationship with the relatively cold coolant; ns formed on said primary surface and extending in a plane parallel to the direction of ow of the gaseous medium; and ns in heat exchange relationship with said primary conducting surface and said owing gaseous medium at a point downstream of said first named ns, said last-named downstream fins extending in a plane other than the horizontal whereby condensate will be drained.
6. A heat transfer surface as in claim 5 in which heat conducting rods are extended from said primary surface to said downstream fins.
References Cited in the le of this patent UNITED STATES PATENTS