US2344588A

US2344588A - Heat transfer device

Info

Publication number: US2344588A
Application number: US373211A
Authority: US
Inventors: Warren S Blauvelt
Original assignee: BLAUVELT ASSOCIATES Inc
Current assignee: BLAUVELT ASSOCIATES Inc
Priority date: 1941-01-06
Filing date: 1941-01-06
Publication date: 1944-03-21
Anticipated expiration: 1961-03-21

Description

March 21, 1944. w, L LT 2,344,588

HEAT TRANSFER DEVICE Filed Jan. 6, 1941 2 @Sheeis-Sheet 1 Inventor Warren 5. Blauvelc,

His Attorney.

March 21, 1944. s, BLAUVELT 2,344,588

HEAT TRANSFER DEVICE Filed Jan. 6, 1941 2 Sheefs-Sheet 2 Inventor y K/ ,His Attorney Warren 5. Blauvelt, I

Patented Mar. 21, 1944 HEAT TRANSFER DEVICE Warren S. Blauvelt, Ann Arbor, Mich, assignor to Blauvelt Associates, Inc., Troy, N. Y., a corporation of New York Application January 6, 1941, Serial No. 373,211

1 Claim.

One of the objects of my invention is the provision of a relatively inexpensive, compact and thermally efficient device for the transfer of heat from one gas, vapor or mixture thereof to another gas, vapor or mixture thereof in their passage therethrough. Throughout the specification and claims I shall, for convenience, refer to the gases, vapors or a mixture thereof simply as gases, intending thereby to cover gases, vapors or mixtures thereof.

The device embodying my invention may be used for various purposes necessitating a variety of designs. For example, it may be used to preheat air for combustion by abstracting heat from ,the combustion gases leaving a furnace in which case the total weight of air passing through the heat transfer device may be of the order of 90% of the weight of the combustion gases passing through said device during any given period. Likewise, it may be used to transmit heat from combustion gases from a warm air heating furnace to the circulated air in which case there may be twenty-five times as many pounds of air heated in a given period as there are pounds of combustion gases cooled.

One of the objects of my invention is the provision of a novel combination of ducts for the passage of heated gases, usually combustion gases, and of gases to be heated, so associated as to facilitate the transfer of heat from the one gas to the other, with corrugated baffles so disposed in both the ducts that carry the hot gases and in those that carry the gases to be heated as to create turbulence in the gases and reduce the thickness of the viscous film which adheres to the walls of the ducts and retards the transfer of heat therethrough.

Other objects of my invention will appear in the specification and the novel features thereof will be pointed out in the claim.

My invention will best be understood by refer ence to the accompanying drawings in which I have illustrated preferred forms thereof and in which Fig. 1 is a plan view of one form of the heat transfer device embodying my invention;

Fig. 2 is a sectionai elevation taken along the line 2-2 of Fig. 1 looking in the direction of the arrows;

Fig. 3 is a sectional view taken along the line 33 of Fig. 1, looking in the direction of the arrows;

Fig. 4 is an end elevation of one of the baiiies over which heated gas flows and the support therefor;

Fig. 5 is an end elevation of one of the baflles which is disposed in a duct and the supportstherefor;

Figs. 6, 7, 8 and 9 are sectional views taken through the baiiies which are disposed in the air ducts and the supports therefor, the four figures showing the battle in different positions with respect to the walls of the ducts within which they are located; and

Fig. 10 is a perspective view, partially broken away, of a heat transfer device in which the heated gases flow through respective ducts in a direction at substantially right angles to the direction of flow of the gases to be heated.

Like reference characters indicate like parts throughout the drawings.

The heat transfer device proper embodying my invention comprises end plates l0 and II which are lower and upper plates in Fig. 2 and which are provided with spaced slots in which are inserted spaced ducts [2 of rectangular cross section the ends of which are welded or otherwise sealed to said plates I 0 and H and which ducts l2 serve to carry the heated gases which flow upwardly from a common inlet l3 (Fig. 3) through the ducts l2 to a common outlet M as best indicated in Figs. 2 and 3. Each of the long side walls ii of each of the said heated gas ducts l2 serves also as a side wall of a duct ll through which the air to be heated flows. In the embodiment of my invention here illustrated, outer walls 45 are side walls for the air ducts I? through which the gas to be heated flows. The heated gas in the embodiment of the invention here illustrated flows upwardly through the ducts i2 and the gas to be heated flows in a substantially horizontal direction through the air ducts ii. A common inlet 18 for the air leads to one side of the heat transfer device through which it is distributed to the air ducts it through which it flows transversely of the heat transfer device to a common air outlet it as best indicated in Figs. 1 and 3 from which the air flows to the places where it is to be used. The heat of the heated gases is thus transferred through a common wall it between the gas duct i2 and the air duct ill to the air to which heat is to be transferred.

When heat is thus to be transferred through a plate or wall, there is present a viscous film of gas that clings or adheres closely to the wall and which serves as a heat insulating material which retards the flow of heat to and from the wall.

In accordance with my invention means are provided for causing turbulence of flow of gas through the ducts carrying both gases or vapors from which heat is to be transferred and those carrying the gases or vapors which are to be heated, thereby reducing the thickness of the viscous films from the wall or walls of the ducts and thus facilitating the transfer of heat. In accordance with my invention corrugated bafiie plates are disposed in both the ducts which carry the heated gases and also in the ducts which carry the gases to be heated, the bafile plates being provided with alternating crests and valleys preferably angular in form at their edges arranged substantially at right angles to the general direction of flow of gas thereover and which cause turbulence in the flow of gases thereby reducing the thickness of the viscous film adhering to the common wall through which heat is to be transmitted from one gas or vapor to another.

Referring particularly to Figs. 4 and 10, I have indicated a bafile plate 20 disposed in a heated gas flue i2, the bafile plate having its ends in common planes and received in an opening 2| in one side of a support 22 as best indicated in Figs. 4, 5 and 10. The heated gases, therefore, flow upwardly across the crests and valleys of the baffle plate 20 on either side thereof.

The flow areas between the crests of the baiile plates and the walls of the duct, progressively decrease from the lower and hotter end of the baffle plate to the upper and cooler end thereof thereby decreasing the flow areas of the gases as their volume decreases.

In the embodiment of my invention illustrated in Figs. 1 to 10, there are thus formed a plurality of ducts I2 (Fig. in which the heated gases flow upwardly.

The air or other gases or vapors to be heated flow through the ducts in a direction, in the embodiment illustrated, substantially at right angles to the upward flow of the heated gases. In

Fig. 2 each of these air ducts i1 is divided into a plurality of ducts by the supports 22 of the baffie plates 20.

When the flow areas between the bafiie and the adjacent wall are progressively decreased in the direction of the flow of gases, the slot 2! in which the bafile plate is received is tapered outwardly as indicated in Fig. 4 in the direction of the flow of gases.

Referring to Figs. 6, '7, 8 and 9 it will be noted that the bafile plate is differently placed relatively to its distance from the side walls of the ducts in which the bafile plate is placed. In Fig. 6 and in Fig. 7 the bafile plates are placed centrally between the side walls so that in each case the distance from the crest of the baffle to the side wall is substantially the sameon each side of the baiile plate. Figs. 8 and 9 illustrate positions of the baffle plates in the outside duct ll where only one of the side walls of said duct is also a side wall of a gas duct. The distance of the battles from the side wall which is also the side wall of the adjacent hot gas duct is greater than the distance of the baiiies on the other side of the baille plate from the outside wall of duct ii, the relative distances of the bafile edges from the two side walls of the duct being determined by the desired temperature at which the gases to which heat is to be transmitted leave the heat transfer device.

It will be understood that the device embodying my invention not only creates turbulence in both the heated gases and the gases to be heated, thereby partially removing the viscous film from the walls of the device, but heat is also transmitted by radiation from the hot gas baffles which absorb heat from the heated air and transmit it to the common wall between the hot air duct and the duct carrying gases to be heated.

The device embodying my invention has been found to be highly eificient in operation and is of comparatively inexpensive construction.

Under some conditions instead of having baffie plates of the character described installed in the ducts carrying the gas to be heated, other means for facilitating the transfer of heat may be used. For example, when the gases are to be cooled from 2700" F. to 200 F. by transfer of heat to air which may be heated from F. to F., the ducts carrying theheated gases could be the same as those already described, while the air ducts would have no separate baffie plates of the character described but the common wall between adjacent ducts might be provided with fins projecting at substantially right angles therefrom into the air duct.

While I have described my invention in its preferred embodiment, it is to be nderstood that the words which I have used are words of description rather than of limitation. Hence, changes Within the purview of the appended claim may be made without departing from the true scope and spirit of my invention in its broader aspects.

What I claim is:

In a heat transfer device, a first duct and a second duct, each substantially rectangular in cross section andhaving a common fiat wall therebetween, means for causing gases to be cooled to flow through said first duct, means for causing gases to be heated to flow through said second duct in a general direction substantially at right angles to the general direction of flow of gases through said first duct, a baffle plate means for supporting said plate within said first duct, said baflle plate being provided with alternating crests and valleys extending substantially at right angles to the general direction of flow of gases through said first duct, the distanc of the crests of said baille plate from the walls of its duct progressively decreasing in the direction of flow of gases through said first duct.

WARREN S. BLAUVELT.