Non-metallic Heat Exchanger

Abstract

A heat exchanger made from fiberglass reinforced plastic includes a pair of end modules interconnected by metal tubes and a cylindrical, encapsulating shell. Headers fit over the outside ends of the end modules and include manifolds for directing one of the fluids passing through the heat exchanger. The other fluid circulates about the tubes in the heat exchanger through openings provided in the end modules.

Description

BACKGROUND OF THE INVENTION

This invention relates to an improved heat exchanger construction.

Generally, heat exchangers are fabricated from metallic materials. The choice of materials is dependent upon the fluids or gases being utilized in the heat exchanger. That is, a highly toxic fluid or gas may require the use of some non-reactive material such as stainless steel or the like for fabrication of the heat exchanger. Most heat exchangers, however, are fabricated from metals because of the temperature ranges involved in the heat exchange process as well as a traditional belief that metal should be used for construction of the heat exchanger.

Because heat exchangers are generally made from metal, a number of metal forming and machining operations are required to fabricate apparatus. Additionally, metal heat exchangers often require extra fasteners or fastening operations such as welding in order to assemble the parts.

The present invention is directed to a heat exchanger and, in particular, a non-metallic heat exchanger which can be fabricated by molding methods thereby simplifying the method of production and providing other benefits.

SUMMARY OF THE INVENTION

In a principal aspect, the present invention comprises a heat exchanger formed of a pair of molded end modules. A manifold is placed over the end modules. The modules are connected by tubes with a shell encapsulating the tubes in the region between the modules. The shell includes openings therein for receipt of fluid or gas that circulates around the tubes thereby effecting an exchange of heat with fluid flowing through the manifold and into the tubes.

It is thus an object of the present invention to provide an improved heat exchanger having a fewer number of parts than prior art heat exchangers and, additionally, having a new simplicity of construction.

Still another object of the present invention is to provide a heat exchanger construction which may be formed by plastic material molding methods.

One further object of the present invention is to provide a heat exchanger construction wherein the separate parts of the heat exchanger may be fastened together by means of an adhesive material.

These and other objects, advantages and features of the invention will be set forth in the detailed description which follows.

BRIEF DESCRIPTION OF THE DRAWING

In the detailed description which follows, reference will be made to the drawing comprised of the following figures:

FIG. 1 is a cut-away perspective view of the improved heat exchanger of the present invention;

FIG. 2 is an exploded partial perspective view of the components forming the heat exchanger of the present invention;

FIG. 3 is a cross-sectional view of the molded end module and encapsulating shell of the improved heat exchanger of the present invention taken substantially along the line 3--3 in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the Figures, the heat exchanger of the present invention is comprised of first and second end modules 10 and 12 interconnected by a cylindrical shell 14. The modules 10 and 12 and the shell 14 are preferably molded from a plastic material. Depending upon the application, the material chosen for the modules 10 and 12 and the shell 14 may be selected by a person skilled in the art of plastic and reinforced plastic materials. The choice of material is dependent upon the following factors, among others, (1) toxicity of fluids or gases through which heat is exchanged, (2) temperature of fluids or gases between which heat is exchanged, (3) pressure range of fluids or gases between which heat is exchanged. Preferably, the plastic material used to form the modules 10 and 12 and the shell 14 will be made from a reinforced plastic material such as a plastic material reinforced by fiberglass.

In any event, the modules 10 and 12 are substantially identical. Thus, the following description will relate to module 12 except as indicated, although the description is equally applicable to the modules 10 and 12. Module 12 includes an end plate 16 having a plurality of parallel tube passages or openings 18 therethrough. Extending outwardly from one side of the end plate 16 is a flange 20. The flange 20 forms a cylindrical portion of the module 12 and has an axis of revolution which is substantially parallel with the centerline axis of the openings 18.

A threaded inlet or outlet opening 22 is molded through a portion of the flange 20. Fluid or gas conduit means may be threaded into the opening 22 to provide for a path of discharge into the interior of the heat exchanger defined by shell 14.

Within the interior of the shell 14 and extending between the openings 18 of modules 10 and 12 are tubes 24. The particular arrangement of the tubes 24 as well as their diameter and placement is dependent upon the design requirements and characteristics of the particular heat exchanger desired. The tubes 24 are preferably of a highly conductive material which is in most cases a metal material, though the remainder of the heat exchanger is made from a molded plastic material.

The tubes 24 are maintained in a properly spaced relationship and supported by baffles 26. The baffles 26 may include extra openings for fluid flow therethrough between the various compartments within the shell 14 defined by the baffles 26. The baffles 26 may contact the shell 14 entirely about its circumference or at various desired portions along the circumference of the baffles 26 depending upon design requirements or desires.

A header or head unit 28 is attached to the outside surface of plate 16. The head 28 is attached to the plate 16 by bolts 30 positioned through appropriate openings in the head 28 and threaded into openings 32 in the plate 16. The portion of the head 28 facing the plate 16 defines a manifold. That is, two cavities 34 and 36 are separated by wall 38. Wall 38 sealingly engages the plate 16 to define the manifold cavities 34 and 36.

An inlet port 40 through the head 28 connects with the cavity 34 and permits fluid flow into the tubes 24 passing through the plate 16 in connection with the cavity 34. A second opening 42 connects through the head 28 with the cavity 36 and thereby also connects with the tubes 24.

The heat exchanger described above is a single pass heat exchanger wherein fluid would flow into the inlet 40 through the tubes 24 associated with the cavity 34 through a single cavity (not shown) in the opposite head 29. In this instance, there is no equivalent wall 38 in the opposite head 29. Thence, fluid flows through the tubes 24, into the cavity 36 and exits through the outlet 42. Of course, any desired arrangement of manifolding, inlet and outlet connections through the heads 28 and 29 may be provided.

The end modules 10, 12 and shell 14 are preferably of a plastic material as described above. Additionally, the end modules 10 and 12 and the shell 14 are interconnected or fastened together by a suitable adhesive appropriate for the particular plastic which has been chosen. In this manner, fastening means such as screws, bolts or the like, or a welding operation is not required. Consequently, it is an easy matter to provide a wide range of heat exchanger constructions utilizing simplified plastic molding techniques. The cost of fabrication and assembly time are thereby reduced.

The exchanger of the present invention can therefore be made by molding the modules 10 and 12 as well as the end plates 28 and 29. The shell 14 may be extruded or molded. The baffles 26 may be molded or stamped. All of these parts are preferably made from a plastic or reinforced plastic by plastic fabrication techniques known to those in the art. The tubes 24 are preferably of a heat conductive metal to enhance heat transfer characteristics of the device. Once the separate parts are formed, they are assembled in the fashion described above.

Importantly, the plastic portions of the heat exchanger may act as an insulator. Thus, heat is retained within the exchanger providing more efficient heat transfer by the tubes 24. This eliminates the necessity for additional external insulation for the heat exchanger and thereby increases the efficiency of the heat exchanger and decreases the cost.

While in the foregoing there has been set forth a preferred embodiment of the invention, it is to be understood that all those embodiments set forth in the following claims as well as their equivalents are to be considered within the scope of the invention.

Claims

What is claimed is:

1. An improved heat exchanger comprising, in combination:

first and second integral end modules formed from a plastic material, each module including a planar end plate, a plurality of parallel tube passages through said end plate, and a circumferential flange projecting from one side of said plate perpendicular to said plate and parallel to said passages with a fluid opening through said flange for conveying a heat transfer fluid;

said first and second modules being positioned with the flanges opposed, said modules being interconnected by a plurality of fluid carrying tubes through said tube openings;

a tube encapsulating shell of plastic material connected to said flanges;

a head attached to each end plate, one head including an inlet opening, an outlet opening and a manifold structure opposed to said end plate for fluid flow to said tubes and the other head including a manifold structure for fluid flow to said tubes; and

means for attaching said heads to the associated plate of said modules.

2. The improved heat exchanger of claim 1 including at least one baffle on the interior of said shell transverse to the axis of said tubes and supporting said tubes within said shell between said plates.

3. The improved heat exchanger of claim 1 wherein said tubes of said heat exchanger are fabricated from a metal.

4. The improved heat exchanger of claim 1 wherein said shell is adhered to said flanges by an adhesive compound.