US2043644A - Heat transfer apparatus - Google Patents

Description

June 9, 1936. c. c. YOUNG 2,043,644

HEAT TRANSFER APPARATUS Filed Sept. 21, 1935 [NVENTOR BY a I 20 V Mm/1 TTORNEY Patented June 9, 1936 UNITED STATES PATENT OFFICE HEAT TRANSFER APPARATUS Cyril 0. Young, Topeka, Kans. Application September 21, 1933. Serial No. 690,386 6 Claims. (01. 138-42) invention relates to heat transfer apparatus and more particularly to apparatus to se cure a highly efficient transfer of heat between the-products of combustion in furnace and the water, steam in the furnace.

a domestic heating or air being heated Most domestic heating furnaces are formed with fines or radiators through which the products of combustion circulate i 11 passing from the firebox or combustion space to the stack. These radiators are intended for giving extended heat transfer surface between the air, water or steam being heated, and the products of combustion of the burning fuel.

At the present time domestic heating furnaces which were originally designed for burning coal are now being modified and adapted for burning oil, natural gas or artificial gas. The radiators and flue ducts for coal furnaces do not always readily lend themselves for efliciently extracting the heat from the combustion products of all types of fuel. On the other hand a distinct effort is being made to cut downthe number of designs of furnaces and arrange the furnaces so that they are adaptable for burning any kind of fuel.

When the products of combustion pass out of the furnace to the stack at a comparatively high temperature a large proportion of the heat available in of the hot products the fuel is lost on account of the passage of combustion out of the chimney. An important factor therefore is to obtain a transfer of the heat products order to bustion gases before they The primary object of to provide a baflie for use pass of the gases to the being heated through the radiators in effectively absorb the heat of the comout of the furnace.

the present invention is in radiators or ducts of terfering with the draft of the furnace or the resistance of the flow of the combustion gases through the fines or radiators.

Another object of the invention is to provide a 50' bailie arrangement by gases may be to continuously bring the hot tact with the metal surfaces heat from the gases and to 55' transferring the heat; by b0 which the combustion held in a constant state of agitation products into confor conducting the provide means for th convection and direct conduction between metal bafiies being heated and the metal forming parts of the flues or radiators.

With these and other objects in view, one feature of the invention contemplates the use of a series .of perforated metal plates which are supported and spaced upon a flexible holder in such a manner that the. plates may be located in ducts of irregular shape and effectively form mixing passages for the flow of flue gases through the ducts.

This and other features of the invention will be understood from the following specification as illustrated in the accompanying drawing in which:'

Fig. 1 is a view in cross section of a duct or radiator of the usual hot air furnace in which the improved baflle string of the present invention is located in the duct, the baflle being shown in plan view;

Fig. 2 is a front elevational View of one plate of the improved bafile;

Fig. 3 is a top plan View of the bafile plate shown in Fig. 2 and showing the mounting of the baffle plates upon a flexible carrier or cable; and

Fig. 4 is a cross sectional view showing the use of the improved baffles in furnace radiators or ducts of different cross sectional shapes.

The baflle forming the subject of the present invention consists primarily of a fiat metal plate In which may be made as a stamping with a die press. When the plate is stamped from sheet metal a central opening 12 is formed in the body of the plate and a series of louvres I4 are formed on one side of the plate having the openings between the louvres so shaped that gases passing through the openings will pass in an upward direction as illustrated in Fig. 2. In the same stamping operation a series of louvres 16 are formed on the opposite side of the plate I2 with the louvre openings arranged to direct the gases downwardly as illustrated in Fig. 2. If the plates were positioned in the radiator with the long axis in a vertical position then the louvres l4 and I6 would tend to direct the gases transversely of the radiator duct. The shape of the stamping dies is such that the plates I0 have substantially the same outline as the cross-sectional shape or area of the flue into which the plates are mounted.

As illustrated in Fig. 2 the plate I0 is stamped to have substantially an elliptical shape, the same as the cross-sectional area of the fine or radiator l8 of the hot air furnace illustrated in Fig. 1.

In mounting the baflle in the radiator [8 the baffle is supported upon and held in spaced relation upon a cable or flexible supporting member 20. To accomplish this a supporting flange 22 is struck out of the body of the plate l6 and is provided with a hole 24 (Fig. 3) by which the plate may be secured to the cable with a cotter pin 26. Preferably the opening l2 is rectangular so that it will fit on a rectangular flexible supporting member and thus hold the plate in a definite fixed supporting position on the cable. With a series of plates mounted on the'flexible carrier a bafiie string is formed which may be readily worked into an irregularly shaped radiator or duct and thus form an efficient heat 7 transferring medium that will accurately con form itself to the shape of the duct or radiator. Such a flexible bafile string can be readily, in-

serted into and removed from a radiator. The

bafile string can be made of any desired length to fill a radiator or duct. Furthermore each. of,

the plates of the baille string is flexible which helps in getting the baflle into position in the radiator even though the radiator surface has irregularities.

Although the shape of the baflie .does not conform exactly to the cross sectional shape of the duct the battle string substantially 16115 the duct and some of the baifles are in contact with all of the metal walls of the radiator. When the gases pass through and aroundthe bafile string the metal plates get hot and by conduction carry .the heat to the walls of the radiator. time the hot gases heat the radiator walls by convection.

By having the louvre spaces arranged to direct some gases upwardly and. other gases downwardly a constant agitation and stirring of the gases is secured so that a high velocity of the gases is eflected and a more efiicient heat transfer carried out.

In the hot air furnace section illustrated in Fig. 1 the air to be heated passes upward around the radiator I 8 entering a duct 28 which is formed between the radiator and an outer wall 30. The gases for heating the air rise through a central duct 32, pass outwardly through a duct 34 and then through both branch ducts of the'radiator l8 in passing to an outlet 36. In passing through the radiator IS the combustion gases pass through and in direct contact with the individual plates of the bailie strings and by getting an efficient heat transfer the gases are cooled to a lower temperature than they would be cooled if the gases passed through the radiator l8 which had no baffles therein. By actual test it has been found that the spaces formed by the louvres in the bafiie plates give adequate spaces for the passage of combustion gases so that a comparatively low pressure drop results in the passage of the gases from the combustion chamber to the outlet flue.

It has been found that when a comparatively large flue or duct is provided for the passage of combustion gases that even though the flue has an irregular shape the outer shell of the combustion gases in contact with'the walls of the radiatorwill be rapidly cooled and form a cooled stream of gases which follows the radiator wall while the central core of gases is hot and remains hot while it passes through the flue. With a battle arrangement for breaking up the streamline flow of the gas a very much more efficient heat transfer of the products of combustion to the walls of the radiator is effected.

In Fig. 4 are illustrated a baffle plate 38 for use'in a flue of substantially oval cross section hyde resins.

At the same and a bafile plate 40 for use in a radiator or flue duct having an irregularly shaped hexagonal passage. The shape of the bafile plates can be made substantially any shape that is desired but it has been found in practice that a comparatively small number of baflle plate shapes are suflicient for use in most of the difierent types of flues or radiators in domestic boilers and furnaces.

The bafile plates are preferably coated with an aluminum paint or with a high temperature resin condensation product such as phenol formalde- The baffles also may be coated with aluminum or zinc metals. Such coatings are particularly useful in resisting corrosion. The .metallic coatings furthermore do not interfere in anyway with the heat transferring ability of The preferred form of the invention having been thus described what is claimed as new is:

l. A domestic heating furnace having flues or radiators comprising ducts for combustion gases whose longitudinal axes are curved, baflle plates. arranged transversely of the ducts and having a shape substantially conforming to the cross sectional area of the ducts, a flexible cable passing through the baffle plates, said baflle plates being fixed to and held in spaced relation upon the cable in such a manner as to readily conform a baiile string to the shape of the duct in which the baffle .is located and openings in the baffle plates having deflecting members arranged to agitate and change the direction of flow of combustion gases passing through the openings.

.2. A domestic heating furnace having flues or radiators comprising ducts for combustion gases whose axes are curved, baflie plates arranged transversely of the ducts and having a shape substantially conforming to the cross sectional area of the ducts, a flexible cable with said baflie plates fixed to and held thereon and so arranged that a string of the bafiie plates will readily conform itself to theshape of the ducts, and louvre openings formed in the greater part of the area of thebafile plates.

3. A domestic furnace having flues or radiators comprising ducts for combustion gases whose axes are curved, substantially flat flexible baffle plates arranged transversely of the ducts and having a shape substantially conforming to the cross sectional area of the ducts, a flexible cable passing through the plates, the plates being fixed upon and held in spaced relationship on the cable, the flexible plates forming a bafile string capable of readily conforming itself to the shape of the duct andopenings in the baflie plates having deflectors adjacent thereto arranged to agitate and change the direction of flow of combustion gases through the openings.

4. A domestic heating furnace having flues or radiators comprising ducts for combustion gases whose axes are curved, and flexible bafiie plates with louvres formed in the major portion of the area of the plates and arranged transversely of the ducts, a flexible carrier with said bafile plates being fixed at their central portion upon and held in spaced relationship by the. carrier to form a baffle string arranged to readily conform itself to the shape of the axis of the ducts.

5. A bafile for a furnace duct or radiator comprising a flexible cable, a series of flexible plates having a shape and cross sectional area of approximately the shape and. cross sectional area of the duct in which they are to be used, mounted upon the cable and held in fixed spaced relation thereon, openings for flue gases formed in the body of the plates with deflecting members adjacent the openings, said plates having a corrosionresisting surface.

6. A baiile for a furnace duct or radiator comprising a series of flexible plates having a shape approximating the shape of the duct in which they are to be used, a flexible carrier passing through the central portions of the plates, means holding the plates in a spaced relationship thereon, said plates having a series of louvres formed of the major portion of the surface of the plates. 5

CYRIL CHARLES YOUNG.

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