JPS6240626B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Over the past few years, energy conservation has become a subject of increasing interest, and increasing the efficiency of energy use is being considered as a means of achieving that objective.
Since boilers and other heating devices for liquids are very commonly used in industrial and residential applications, increasing the efficiency of these devices naturally contributes significantly to energy savings.

It has long been known that increased efficiency in heating liquids is obtained by increasing the heat exchange surface area between the heat source and the liquid being heated. Various designs of liquid tanks have been proposed, and one that has been shown to have potential for use is an annular tank. Generally, in devices of such design, the gaseous combustion products are introduced into a cylinder formed by the inner wall of an annular tank. The hot gas passes over the internal wall, which acts as a heat exchange surface to heat the liquid in the tank. The gas is then planned to be redirected onto the outer walls of the annular tank, in which case both said walls act as heat transfer surfaces. In some cases, fins, convoluted surfaces, or area-enhancing means have been designed to improve heat transfer efficiency, but such devices impede hot gas flow and are expensive in terms of assembly costs. Moreover, because the structure became complicated, it showed failure to some extent. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a means for increasing the amount of heat transfer, which is relatively simple and inexpensive in structure, and which operates to avoid the effects of boundary layers that inhibit heat transfer functions, and a sufficient amount of hot gas source. The object of the present invention is to provide a boiler that maximizes the gain in heat transfer efficiency in combination with an annular tank having an annular tank.

The present invention relates generally to the heating of liquids, and more particularly to the heating of liquids.
This invention relates to a highly efficient and compact boiler of simple and relatively inexpensive design. This boiler has the following basic components:
It includes a hot gas source such as a combustor, an annular water tank, and heat transfer enhancement means for maximizing heat transfer from the hot gas through the inner and outer walls of the tank to the water in the annular tank.

An interior chamber is formed at least in part by the interior wall of the tank, and combustion product gases occurring within the combustor are channeled through a group of superimposed radial fins mounted in heat transfer relation to the interior wall. It is passed along a tortuous path through the interior chamber. The boundary layer that normally occurs along the fins and inner walls is disrupted by the disturbances imparted to the gas by the rotational bias adjacent to the fins.

After passing through the inner chamber, the gas is redirected along the outer wall of the annular tank via a jet impingement heat transfer device, where the element with a multi-perforated wall is directed toward an adjacent solid wall. This gas is formed in the form of a jet. Furthermore, the boundary layer is collapsed,
The amount of heat transfer is increased and the efficiency of heating the water is improved.

In FIG. 1, the preferred type of liquid heating device shown is in the form of a water boiler enclosed within a double-walled insulating jacket 11. In FIG. The basic working elements are formed in part by the annular water tank 12, by the inner wall 20 of the annular tank 12 through which the gas passes through the outer chamber 18, and in part by the outer wall 22 of the annular tank 12. A combustor 14 is arranged to first ignite the hot gases passing through the formed interior chamber 16. These chambers are equipped with jet impingement type heat transfer increasing elements, the details of which will be described later.

The annular tank 12 is formed into a closed vessel by a concentric arrangement of inner and outer walls 20 and 22, an end plate 24, and an end cap 26. The water to be heated is passed through the end plate 24 to a sealed inlet line 28.
into the annular tank. Hot water passes through end cap 26 to similarly sealed outlet line 30
from the annular tank. Entrance line 28
A deflection plate 32 is disposed within the annular tank near the entry point of the inlet line 28 to prevent water from flowing directly from the outlet line 30 to the outlet line 30 . This deflection plate 3
2 is curved in the same shape as the inner inner cylindrical wall 20 and is attached to this inner wall and extends radially towards the outer cylindrical wall 22. It has the form of a portion of a disc with its central area placed against a 90° corner and approximately opposite the entry line 28.

The combustor 14 can be of any conventional type, but is preferably a screen combustor with fuel, such as gas, from an inlet 29 and air from a blower 31 for combustion. The blower outlet was sealed through the center of the end plate 24 adjacent to the spark igniter 40, which was also sealed through the end plate 24 and located adjacent to the screen of the combustor 14. It has an electrode 41.

The interior chamber bounded by the inner wall 20 of the tank, with its center open, has proven effective in directing hot gases to the wall 20 by means of a high temperature insulating material 34. The insulating rod 34 preferably has a beveled end that faces the combustor and the beveled end is used to support and center the screen of the combustor 14.

Superimposed on the inner wall 20 are rows or groups of fins 36, 37, 38, 39 extending radially inwardly from the wall. Each group of fins is 18 in number and is arranged symmetrically and spaced at 20° intervals around the inner surface of the wall 20. These fins are made of a highly heat conductive material and are either integral with the inner wall 20 or welded or soldered to the inner wall with good heat conductivity.

The arrangement of fin groups 36 and 37 is clearly shown in FIG. 2, although four such fin groups are used in the systems shown in FIGS. 1 and 2.
The fins of each group are rotationally offset from adjacent groups. In FIG. 2, which shows the case of fins having a 20 DEG spacing, the desired offset of the fins of group 36 to the fins of group 37 is approximately 10 DEG as shown.
The fins of subsequent fin groups 38 and 39 are likewise offset by 10° from the adjacent group.

Although the slots between the fins lie in a plane passing through the axis of the inner wall 20, the staggered arrangement of each group or row relative to adjacent groups provides a tortuous path for hot gas flow and a This creates disturbances that disrupt the boundary layer normally associated with use.
In other words, the fins are spaced and spaced such that the resistance to gas flow axially through the chamber 16 is not significantly increased as would be the case with transverse fins extending radially inwardly from the inner wall 20. It is located. On the other hand, if the fins have no rotational angular deviation and the fins of all groups are aligned, the straight flow of gas will disrupt the boundary layer enough to promote good heat transfer. It would not be possible.

At the end of the annular tank 12 opposite the combustor, hot gas flows from the inner chamber into the pressure chamber 43;
It is forced outwardly by the deflector and flows into an outer annular chamber 18 formed by the inner wall of the insulating jacket 11 and the outer wall of the tank 12.

A series of jet impingement members are disposed within the outer chamber 18 and extending along substantially its entire length. Although the precise design of these components varies, the key design considerations are to create a jet of hot gas that impinges on the heat transfer surface in a manner that disrupts the boundary layer, as discussed in more detail below. It is in. However, in the particular construction shown in FIG.
As shown in the partial view of the figure, it has a large number of perforations and is bent and formed.

In particular, FIG. 3 shows a section of the sheet metal, in which the holes are perforated at regular intervals and the fold lines are represented. The first row of holes 51 are symmetrically offset from the second row of holes 52, and this arrangement is similarly repeated for the following rows. This length of material is folded along line 53 and similar fold lines as shown in FIG. The resulting corrugated or convoluted sheet is then fitted around the outer tank wall 22 to form the rectangular groove described above. These grooves extend over almost the entire length of the wall 22, or are formed in groups of grooves that overlap one another. The desired jet-forming holes and opposing non-porous heat transfer surfaces can be configured in a variety of ways. Applicable theoretical considerations and comparable fabrication techniques are set forth in US Pat. No. 3,804,159, owned by the assignee of the present application, and the relevant contents of that patent are incorporated herein by reference.

The important point is that the staggered arrangement of holes is such that each hole provided in a given groove wall allows gas to eject and impinge on the non-porous wall, collapsing the boundary layer and improving heat transfer efficiency. It is to be placed facing a non-perforated wall.

For representative grooves 57 and 58 in FIG. 2, groove 57 is open into high pressure chamber 43 and groove 58 is closed. This continuous array of open and closed grooves is repeated around the outer circumference of the structure.

Adjacent to the plate 24, another pressure chamber 49 is formed, and the sequential manner of opening and closing grooves is reversed. In other words, the representative groove 57 that opens into the pressure chamber 49 is closed from the pressure chamber 49, while the representative groove 58 that is closed from the pressure chamber 43 opens into the pressure chamber 49. Exhaust line or passage 61 is insulating shell 1
1 and communicated with a pressure chamber 49 for conveying waste gas.

The heat exchange element in the outer chamber 18 can be simply fabricated as a perforated cylinder surrounding the outer wall 22, and the jet is formed by the holes of the perforated cylinder and is ejected towards the outer wall. Various designs can be implemented to break up the laminar flow or break up the boundary layer with perforated or slotted fins to ensure that the hot gas re-impinges face-to-face of adjacent fins.

[Brief explanation of the drawing]

1 is a cutaway elevational view of a liquid heating system embodiment of the present invention; FIG. 2 is a cross-sectional end view of the system shown in FIG. 1 taken along line 2--2 of FIG. 1;
Figures 1 and 4 illustrate one method of construction and details of the heat transfer mechanism used in the embodiment of Figures 1 and 2. 11... Insulating jacket, 12... Annular water tank,
14...Combustor, 16...Inner chamber, 18...Outer chamber, 20...
Inner wall, 22... Outer wall, 24... End plate, 26... End cover, 2
8... Inlet line, 29... Inlet, 30... Outlet line, 31... Air blower, 32... Deflection plate, 34... Insulating rod, 36, 37, 38, 39... Fin group, 40...
Spark igniter, 43...pressure chamber, 45...deflection device, 4
9... Pressure chamber, 51, 52... Hole, 53... Line, 5
7, 58...groove.

Claims (1)

[Scope of Claims] 1. An annular tank containing a heated liquid having a concentric inner wall and an outer wall acting as heat exchange surfaces, with an inner chamber formed within the inner wall, and spaced from and surrounding the outer wall. an outer shell having an outer chamber formed between the outer shell and the outer wall; a device for circulating hot gas first through the inner chamber and then through the outer chamber; A boundary which is arranged in the inner chamber in a heat transfer relationship and forms a winding path along the inner wall for the flow of the high temperature gas, thereby causing disturbance in the gas. A plurality of heat exchange effect enhancing fins that collapse layers, a jet forming device for forming the high temperature gas in the outer chamber into a jet, and a heat transfer device for conducting heat in the outer chamber to the outer wall. a boiler, wherein the heat transfer device has a non-perforated surface facing the jet forming device and arranged to impinge on the non-perforated surface portion when the jet is formed. 2. the jet forming device and the heat transfer device have at least one jet impingement member in thermal conductive relationship with the outer wall of the annular tank, the impingement member having opposing surfaces having jet forming holes therein; The holes on each opposing surface face the unperforated portions of the opposing surfaces,
2. A boiler as claimed in claim 1, wherein the hot gases directed through the holes form a jet impinging on the non-perforated portion. 3. Each jet impingement member has a metal sheet formed into a plurality of rectangular corrugations, the corrugations being rectangular in shape extending perpendicularly between the outer shell and the outer wall and extending along the length of the outer wall. Claims 1 and 2 have opposing surfaces for defining a channel, each said surface having a plurality of jet-forming holes arranged so as to face the unperforated portions of the mutually opposing surfaces. Boiler described in item 2. 4. The apparatus for directing hot gas includes a combustor disposed to ignite hot gas entering the interior chamber and a combustor disposed within the interior chamber to assist in directing the hot gas toward the interior wall. 2. A boiler as claimed in claim 1, including a deflection device of high temperature insulating material centrally located. 5. The plurality of fins disposed within the inner chamber include a plurality of overlapping rows of fins extending radially inward from the inner wall, each row of fins being offset relative to an adjacent row of fins. The boiler described in the range 1 above. 6. Each fin row includes a plurality of fins arranged equiangularly apart from each other, and the spacing angle between the fins is approximately twice the angle by which each fin row deviates from an adjacent fin row. A boiler according to claim 5.