US3370644A - Method of increasing the rate of heat transfer - Google Patents

Description

Feb. 27, 1968 w. B. DAILY E L 7 I METHOD OF INCREASING THE RATE OF HEAT TRANSFER Filed Dec. 28, 1965 38 ,la" UUUEJEEIEJ UEIUEHEE] EIUE1- EUEEIE BEE BEBE INVENTORS [710 J dfaeaa v awry/[M59675 United States Patent 3,370,644 METHOD OF INCREASING THE RATE OF HEAT TRANSFER William B. Daily, and Elio J. Speca, Wellsville, N.Y., as-

signors to The Air Preheater Company, Inc., New York,

N.Y., a corporation of Delaware Filed Dec. 28, 1965, Ser. No. 516,936 1 Claim. (Cl. 165-1) ABSTRACT OF .THE DISCLOSURE The method of increasing the rate of heat transfer between fluids in a heat exchanger by electronically increasing the circulation within a fluid and simultaneously removing particulate matter therefrom without mechanically increasing the resistance of the passageways to the flow of fluid therethrough.

This invention relates generally to heat exchangers, and particularly to a method by which the heat transfer rate of a recuperative heat exchanger may be substantially increased.

Fluids flowing through passageways in heat exchangers tend to stratify and produce zones of laminar flow which insulate rather than promote the transfer of heat. Consequently heat exchangers constructed according to conventional heat exchanger standards frequently assume large proportions as a compensation for their low coefficient of heat transfer. To overcome this objection as to size and low heat transfer coefl'icient various forms of extended surface have been placed in the heat exchanger along the walls of the heating fluid or the fluid to be heated. Such extended surface means disrupt the laminar flow and create a degree of turbulence that enhances the rate of heat transfer but also increase the resistance of the passageways to the flow of fluid therethrough.

Thus an optimum design of heat exchange equipment would afford simultaneously a maximum rate of heat transfer and a minimum resistance to the flow of fluids therethrough, and this invention therefore has for its principal object the provision of a heat exchange device that has a high rate of heat transfer and a low resistance to the flow of a fluid.

According to the invention it has been discovered that 4 zones of stratified fluid flow may be disrupted without substantial variation in the resistance to the flow of fluid therethrough by causing an ionic discharge to traverse the several stratifled layers of fluid flow. The manner that this discovery has been applied to the invention at hand may be more readily understood by referring to the accompanying drawings in which:

FIGURE 1 is a sectional elevation of the heat exchanger according to the invention.

FIGURE 2 is a horizontal section of FIGURE 1 as seen from 2-2, and

FIGURE 3 is a horizontal section of a modified form of heat exchanger.

A heat exchanger embodying the present invention is shown in FIGURE 1 wherein a heating fluid admitted to a housing through an inlet 12 is directed through grounded tubes 14 to an outlet 16 and a connected exhaust duct. A fluid to be heated is admitted to the housing through an inlet port 22 where it flows around the tubes 14 to receive heat from the heating fluid inside said tubes before it is exhausted to the outlet port 26 as a heated fluid.

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The tubes 14 extend axially through the housing 10 between apertured tube sheets 28 and 34 having one or more baflle plates 36 preferably positioned therebetween to effectively increase the dwell period of any fluid passing over the tubes between inlet and outlet ducts. Each tube 14 contains a centrally mounted discharge electrode 38 supported by insulators 40 which electrically isolate the electrodes 38 from the grounded tubes 14. The discharge electrodes 38 are themselves electrically charged by being connected to a suitable source 42 of high voltage direct current, and then discharged across the space which surrounds each electrode to the grounded tubes 14. As the flow of ions moves from the discharge electrode 38 to the grounded tube 14 an electric Wind is produced transversely with respect to inlet and outlet ports so as to increase the turbulence of the fluid inside the tubes and to preclude conditions of laminar flow. Inasmuch as laminar flow conditions are obviated without the necessity of placing extended surface means in the fluid stream, there is an increase of heat transfer without a corresponding increase in pressure drop of the fluid.

FIGURE 3 shows a modified form of the invention wherein the tubes of the design illustrated in FIGURES 1 and 2 have been replaced by plates 44 spaced apart according to a predetermined plan to provide alternate inter-plate passageways 14 and 48 for the heating fluid and the fluid to be heated. Ionic discharge electrodes 38 may be subsequently positioned in the passageways for one or both of the fluids in accordance with the foregoing disclosure to increase the rate of heat transfer of the several fluids.

While this invention has been described with reference to the several embodiments illustrated in the drawing it is evident that various changes may be made without departing from the spirit of the invention, and it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. The method of increasing the rate of heat transfer between a heating fluid and a fluid to be heated in a heat exchanger having a housing with surface members forming walls between passageways for said fluids and openings which comprise inlet and outlet ports for said fluids flowing through said passageways, said method comprising the steps of electrically grounding said wall forming surface members, effecting a discharge of ions in the passageway for at least one of said fluids to simultaneously ionize the fluid it traverses and the particulate matter entrained therein so as to attract the ionized particles to the grounded surface, and periodically terminating the discharge of ions to permit fluid flowing through said passageways to flow directly therethrough and remove deposits from said wall forming surface members.

References Cited UNITED STATES PATENTS 1,916,337 7/1933 Schmidt 165-1 2,605,377 7/1952 Kaehni et a1. 1651 FOREIGN PATENTS 373,051 4/1923 Germany.

ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner.

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