Note: Descriptions are shown in the official language in which they were submitted.
CA 02199342 2004-02-18
1
TITLE OF THE INVENTION:
Polymer Plastic Heat Transfer Piping
FIELD OF THE INVENTION
The present invention relates to polymer plastic heat transfer piping and, in
particular,
refrigeration piping used for ice rinks.
BACKGROUND OF THE INVENTION
An ice rink has a surface, usually of concrete or sand, in which there is
embedded
hundreds of feet of refrigerant pipe or tubing. Water is sprayed upon the
surface. Coolant
circulated through the refrigerant pipe or tubing, effects a heat transfer
with the water as it lies
on the surface, causing ice to be formed on the surface.
For a number of years refrigerant pipe or tubing has been made of polymer
plastic.
2 0 When polymer plastic was first introduced piping with an inner diameter of
one inch had a
wall thickness of approximately .125 of an inch. In order to increase the
efficiency of the heat
transfer, experiments were attempted with a wall thickness of .085 of an inch.
It was found
that this wall thickness was not sufficiently robust for refrigeration piping
applications. The
pipe or tubing tended to collapse while being covered with concrete and was
readily
2 5 punctured. As a result of this experience, a minimum wall thickness of
.100 of an inch was
adopted for piping with an inner diameter of one inch. It remains recognized
in the industry,
however, that if a robust refrigeration piping could be made with a thinner
wall thickness,
there would be more efficient heat transfer.
CA 02199342 2004-02-18
2
SUMMARY OF THE INVENTION
What is required is a robust polymer plastic heat transfer piping with a wall
thickness
of less than .100 of an inch.
According to the present invention there is provided a polymer plastic heat
transfer
piping which includes a tubular body having an exterior surface and an
interior surface. In
order for the tubular body to remain sufficiently robust for a refrigeration
piping application
with a thinner wall, a plurality of vanes must be positioned on either the
exterior surface, the
interior surface or both. It is preferred that the vanes be positioned on both
the exterior
surface and the interior surface. The tubular polymer plastic body has a wall
thickness which
is between S.0% and 8.5% of its inner diameter. Piping with a one inch inner
diameter has a
wall thickness of less than .085 of an inch. Piping with a two inch inner
diameter has a wall
thickness of less than .165 of an inch.
When polymer plastic refrigeration piping is set in concrete some shrinkage
occurs.
This shrinkage leaves air voids which serve as an insulator and, therefore,
are detrimental to
the required heat transfer. A polymer plastic refrigeration piping with a
thinner wall thickness
and vanes on the exterior surface has a number of advantages. Firstly, the
vanes reinforce the
2 0 walls of the refrigeration piping, making them more robust. Secondly, the
thinner wall
thickness promotes more effective heat transfer. Thirdly, the vanes provide a
greater surface
area over which a heat transfer can be effectal. Fourthly, the vanes assist in
improving the
contact between the refrigeration piping and the concrete; securely anchoring
the refrigeration
piping notwithstanding some shrinkage occurring.
The flow of coolant through polymer plastic piping is a substantially laminar
flow.
This means that not all of the coolant comes in contact with the interior
surface and, therefore,
not all of the coolant is being fully utilized for heat transfer. A polymer
plastic refrigeration
piping with a thinner wall thickness and vanes on the interior surface has a
number of
3 0 advantages. Firstly, the vanes reinforce the walls of the refrigeration
piping, making them
more robust. Secondly, the thinner wall thickness promotes more effective heat
transfer.
Thirdly, the vanes provide a greater surface area over which a heat transfer
can be effected.
CA 02199342 2004-02-18
3
Fourthly, the vanes can be used as a means of promoting a non-laminar flow
through the
refrigeration piping for more efficient heat transfer to the coolant. One
example of a means
for using the vanes to promote non-laminar flow is by having the vanes
arranged in a helical
pattern.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more apparent from the
following description in which reference is made to the appended drawings,
wherein:
FIGURE 1 is an end view of a first embodiment of polymer plastic heat transfer
piping constructed in accordance with the teachings of the present invention
with vanes on the
interior surface.
FIGURE 2 is an end view of a second embodiment of polymer plastic heat
transfer
piping constructed in accordance with the teachings of the present invention
with vanes on the
exterior surface.
FIGURE 3 is an end view of a third embodiment of polymer plastic heat transfer
piping constructed in accordance with the teachings of the present invention
with vanes on the
2 0 exterior surface.
FIGURE 4 is a side view, in section, of the polymer plastic heat transfer
piping
illustrated in FIGURE 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment, a polymer plastic heat transfer piping generally
identified
by reference numeral 10, will now be described with reference to FIGURES 1
through 4.
CA 02199342 2004-02-18
4
Referring to FIGURE 1, polymer plastic heat transfer piping 10 includes a
tubular
body 12 having an exterior surface 14, an interior surface 16, and an inner
diameter 17. The
wall thickness of for polymer plastic heat transfer piping 10 depends upon
inner diameter 17.
It is preferred that the wall thickness be less than 8.5% of inner diameter
17. This makes the
wall thickness less than .085 of an inch when the inner diameter is one inch.
This is a
thickness that was found inadequate with previous polymer plastic heat
transfer piping.
Beneficial results have been obtained using a wall thickness of less than .065
of an inch, or
6.5% of inner diameter 17. It is believed that the wall thickness can be made
as thin as .050
of an inch, or 5% of inner diameter 17. A wall thickness of less than .050 is
not
recommended. In accordance with the present invention, a plurality of vanes 20
are
positioned on either interior surface 16, as illustrated in FIGURE 1, or a
plurality of vanes 18
are positioned on exterior surface 14, as illustrated in FIGURE 2. Referring
to FIGURE 3,
vanes can also be positioned on both interior surface 16 and exterior surface
14. Referring to
FIGURE 4, vanes 20 are arranged in a helical pattern for the purpose of
promoting a non-
laminar flow of coolant. The illustrated configuration has 16 of vanes 18 and
16 of vanes 20.
It takes 36 inches in pipe length for helical pattern of vanes 20 to rotate
about 360 degrees.
The use and operation of polymer plastic heat transfer piping 10 will now be
described with reference to FIGURES 1 through 4. Tubular body 12 is set in
concrete. As
2 0 the concrete sets, some shrinkage occurs. This shrinkage tends to leave
air voids. Vanes 18
improve the contact between tubular body 12 and the concrete and securely
anchor heat
transfer piping 10 in the concrete, notwithstanding such air voids. Vanes 18
and 20 reinforce
the walls of the heat transfer piping 10, making them more robust. The thinner
wall thickness
promotes more effective heat transfer, and vanes 18 and 20 provide a greater
surface area over
2 5 which such heat transfer can take place. Referring to FIGURE 4, the
helical arrangement of
vanes 20 promotes a non-laminar flow through heat transfer piping 10. This
allows the
coolant to be more efficiently used for heat transfer.
CA 02199342 2004-02-18
It will be apparent to one skilled in the art that modifications may be made
to the
illustrated embodiment without departing from the spirit and scope of the
invention as
hereinafter defined in the Claims.
