AU754348B2 - Heat exchanger coil and apparatus for forming same - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicants: PAUL JOHN ABBOTT GUISEPPE ABBOTT DANNY BEGO Invention Title: HEAT EXCHANGER COIL AND APPARATUS FOR FORMING SAME The following statement is a full description of this invention, including the best method of performing it known to us: HEAT EXCHANGER COIL AND APPARATUS FOR FORMING SAME This invention relates to a heat exchanger coil, and an apparatus for forming such a coil, and more particularly, but not exclusively, a coil formed from copper and for incorporation within a housing, whereby hot fluid passing through the housing heats a fluid passing through the coil to thereby form a heat exchanger.

25 It is known to provide a heat exchanger of the above type, and one particular, but not the only, application is for use when camping at sites where there are no facilities to provide hot water, such as for showering. With such an apparatus, hot water from the 30 engine cooling system of a vehicle is passed through the :housing, and water from an available source, such as a river or dam, is pumped through the coil of the heat exchanger, whereby to become heated as it passes therethrough and thereafter supplied or delivered to a handheld shower nozzle or shower rose for direction over the body of the person showering.

Although such known heat exchanger units have proved satisfactory for such showering and other purposes, there has been a need to increase the heat exchange efficiency of units whereby to achieve higher temperatures of heated fluid, and it is therefore a primary object of the present invention to achieve such higher efficiency and therefore heated fluid temperatures.

In accordance with the invention it has been determined that by partially flattening the copper tube forming the coil through which the fluid to be heated is passed, a greater wall surface area is created per volume of fluid passing through the coil, and a greater heat transfer through the wall to the fluid is achieved.

Therefore, in accordance with the present invention there is envisaged a heat exchanger element for a heat exchanger and formed from tubing which has been partially flattened.

Preferably the tubing is metal tubing.

Preferably the tubing is formed into an elongate coil, or alternatively, the tubing is formed into a planar spiral.

~Preferably in the case of an elongate coil, the coil is retained within an elongate housing through which hot fluid is passed to heat fluid passing through the coil.

Alternatively, in the case of a planar spiral tubing, such may be placed in a position exposed to the sun *.-whereby to act as a solar heater.

One problem which has been encountered when forming elongate coils of partially flattened tubing is in achieving a consistent coil free of significant buckling, distortion, denting, or other malformations, and the present inventor has spent many months attempting to achieve such consistency before successfully developing an apparatus suitable for the purpose.

Therefore, also in accordance with the present invention, there is envisaged an apparatus for forming a length of partially flattened tubing into an elongate coil of the type defined above, said apparatus comprising a rotatable elongate shaft onto which the partially flattened tubing is wound as the shaft is rotated, means to guide a length of said tubing onto said shaft, means to support said shaft for longitudinal axial movement relative to said guide means, and whereby said shaft, said guide means and said tubing cooperate with each other as said shaft is rotated whereby to axially move said shaft as the tubing is progressively formed into an elongate coil around and along said shaft.

Preferably said guide means defines a channel for o*o said tubings and is carried by a hinged support member pivotable into a position engaging said shaft and said tubing, and means are provided to clamp said support member and said guide member into position engaging said shaft and 25 said tubing.

Preferably the shaft is manually rotated by a handle at one end thereof.

30 Alternatively the shaft may be rotatably driven by a motor.

One preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is an exploded view of a heat exchanger incorporating an elongate heat exchanger coil in accordance with the preferred embodiment of the invention, Figure 2 is a perspective view of the preferred apparatus for forming the heat exchanger coil for the heat exchanger of Figure 1, with the apparatus shown in a nonoperating mode, and Figure 3 is a perspective view of the apparatus of Figure 2 and shown in the operating mode.

Referring to Figure 1 of the drawings, the heat exchanger, generally indicated as 10, and incorporating the elongate heat exchange coil 11 of this preferred embodiment of the invention and formed from copper tubing, has an elongate housing or casing made up of two halves 12a and 12b within which the coil 11 is received. The housing halves 12a and 12b have abutting circumferentially extending flanges 13a and 13b which are fastened together o. by bolts or similar fasteners passing through aligned holes 14a and 14b in the respective flanges. The end walls of each casing half have ports 15a and 15b therethrough, and through one of which (15a), at the end wall of housing half 25 12a, hot fluid is delivered to flow through the housing 11 and out through the equivalent port at the end wall of the ther housing half 12b. Fluid to be heated is passed through the port 15b of one housing half into the coil 11 via an inlet duct 16a at one end of the coil and aligned 30 with, and received within, port 15b. Heated fluid passes out of the coil through the equivalent port 15b in the end wall of the other housing halve via an outlet duct 16b aligned with, and received within, the port 15b. The coil 11 is completed by an elongate copper tube 17 received within, and along the length of, the coil and fitting tightly and snugly within the inside diameter of the coil as shown. The inner tube 17 may be roll formed, and the roll forming may be accomplished by utilising the shaft of the apparatus to be later described, and utilising an appropriate roll forming jig.

Turning to Figures 2 and 3 of the drawings, the apparatus as indicated as 18 for forming the heat exchanger coil 11 of Figure 1, and which is also in accordance with a preferred embodiment of the invention, comprises a base frame 19 made up of two elongate members 20 with underlying support members 21 at either end.

The base frame supports an elongate shaft 22 mounted for rotation by a handle 23 in a pair of spaced apart journals or bearings 24 and 25 bolted at 26 to the elongate members 20, and whereby the shaft is free to rotate within the journals or bearings whilst also being free to move axially with respect to the journals or bearings.

Although Figures 2 and 3 both show a number of turns of coil wound onto the shaft, in practice the end of a length of copper tubing 27, which has been previously partially flattened between a pair of flattening rollers, is received within a channel 28 between a pair of lugs 29 25 and 30 mounted on the shaft, whereafter upon rotating the shaft to form some preliminary coils, a guide member 31 having a pair of wall defining a slot 31a therebetween, and mounted on a hinge support member 32, is pivoted down to engage over the tubing and against the shaft with the .30 tubing in the slot 31a. The coil is then formed by continued rotation of the shaft, and the combined interaction between the guide member 31 and the tubing 27 it coils onto the shaft causes the shaft to move axially in the direction of the end of the shaft carrying the handle 23, and an elongate coil of tubing is progressively formed along and around the shaft 22.

In order to clamp the support member 32 and the guide member 31 into position engaging the shaft and the incoming portion of the tubing 27 to guide the tubing onto and around the shaft, a toggle type clamping mechanism 33 is provided mounted on, and bolted at 35 to, a support bracket 34 bridging the shaft between the journals or bearings 24 and 25, with feet 36 forming part of the support bracket being bolted at 37 to the elongate members of the base frame 19.

An outer cylindrical member (not shown) may also be incorporated on the apparatus and surrounding the shaft 22 to confine, and therefore define, the outside diameter of the coil as it is formed around the shaft.

It is has been found that with a heat exchanger incorporating the heat exchanger coil of this preferred embodiment of the invention, and passing engine cooling water from a vehicle at running temperature through the housing of the heat exchanger, water temperatures of up to *6000 can be achieved with water to be heated passing through the coil 11 at a rate of 4.4 litres per minute.

In some applications the fluid passing through 25 the housing may be water from the cooling system of an engine, such as a vehicle engine, or the fluid may be from a hot gas burn or even the exhaust gases from an engine, such as a vehicle engine.

Claims (9)

1. A heat exchanger element for a heat exchanger such as a hot water heat transfer system for use for showering in camping conditions said element formed from metal tubing which has been partially flattened and the tubing formed into an elongate coil around a central tube such that the flattening provides a greater wall surface area per volume of fluid passing through the coil and a greater heat transfer through the central tube wall is achieved.

2. A heat exchanger element as claimed in claim 1 wherein the tubing is formed into a planar spiral.

3. A heat exchanger element as claimed in claim 1 or 2 wherein the coil is retained within an elongate housing through which hot fluid is passed to heat fluid passing through the coil.

4. An apparatus for forming a length of partially flattened metal tubing into an elongate coil, said apparatus including: a rotatable elongate shaft onto which the partially flattened tubing is wound as the shaft is rotated, means to guide a length of said tubing onto said shaft, means to support said shaft for longitudinal axial movement relative to said guide means, and whereby said shaft and said tubing cooperate with each other as said shaft is rotated whereby to axially move said shaft as the tubing is progressively formed into an elongate coil around and along said shaft.

An apparatus as claimed in claim 4, wherein said guide means defines a channel for said tubing and is carried by a hinged support member pivotable into a position engaging said shaft and said tubing, and means are provided to clamp said support member and said guide member into position engaging said shaft and said tubing.

6. An apparatus as claimed in claims 4 or 5, wherein the shaft is adapted to be manually rotated by a handle at one end thereof.

7. An apparatus as claimed in claims 4 or 5 wherein the shaft is rotatably driven by a motor.

8. A heat exchanger element as defined in any one of claims 1 to 3 formed by an apparatus for forming a length of partially flattened metal tubing into an elongate coil as defined in any one of claims 4 to 7.

9. A heat exchanger substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings. An apparatus for forming a length of partially flattened metal tubing into an elongate coil substantially as hereinbefore described with reference to Figures 2 and 3 of the accompanying drawings