Abstract:
A heat distribution apparatus comprising a fluid conduit having a peripheral wall defining a flow passage and a pair of fluid capillaries extending along the wall and secured thereto. The capillaries being connected to one another in series to provide a fluid flow path along one of the capillaries and a return path along another of said capillaries to convey heat exchange fluid to transfer heat between the flow passage and the heat exchange fluid.

Description:
[0001]     This application claims priority from U.S. Patent Application No. 60/507,127 filed on Oct. 1, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to methods and apparatus for distributing heat to or removing heat from remote locations.  
       DESCRIPTION OF THE PRIOR ART  
       [0003]     It is often necessary to distribute heat to or remove heat from remote locations to inhibit freezing at that location. For example, in a fluid conveying system such as a water supply system, there is a danger during cold weather that fluid in the conduit will freeze. There are many proposals to supply heat to such a conduit such as by wrapping an electric heating cable about the conduit but these have tended to be used in locations close to. an electrical power source. Moreover, such installations tend to be used intermittently due to their relative inefficiency and power consumption.  
         [0004]     An alternate form of heating apparatus is shown in Canadian Patent 2019590 in which a self-regulating heating cable is inserted within a fluid conduit. With this arrangement it is possible to insulate the conduit to conserve energy and to regulate the power consumption due to the self-regulating nature of the cable. This arrangement has found wide-spread use, particularly in domestic water supplies in remote areas. The heating effect obtained from this installation is however limited to the available length of the heating cable which becomes a limiting factor in some installations. Moreover, the electrical system is prohibited in some environments such as sewers or drains that may contain methane because of the possibility of ignition of sewer gas. There is also a reticence to use electric heating cables in some environments where the cable may be exposed, such as roof and gutter de-icing, where damaged cables may come in contact with water and can result in fire when breakdown occurs. Proper electrical installation ensures the safe operation of such devices but nevertheless there is always a risk of improper installation.  
         [0005]     It will also be appreciated that such cables cannot function to extract heat from the fluid.  
         [0006]     It is therefore an object to the present invention to provide a method and apparatus for providing heat to remote locations in which the above disadvantages are obviated or mitigated.  
       SUMMARY OF THE INVENTION  
       [0007]     According to one aspect of the present invention there is provided a fluid conduit having a peripheral wall to define a flow passage and a pair of fluid capillaries extending along the wall. The capillaries are connected in series and secured to the wall. Fluid may then flow along one of the capillaries in one-axial direction and be returned through the other capillary in the opposite direction. The capillaries are connected to a source of heat exchange fluid and thereby transfer heat through the wall of the conduit between the heat exchange fluid and fluid within the conduit.  
         [0008]     In an alternative embodiment, the capillaries may be contained within the peripheral wall defining the conduit. In both embodiments an external jacket may be applied to provide insulation to the conduit.  
         [0009]     In an alternative aspect of the invention there is provided a heating apparatus comprising a pair of concentric conduits and an end-cap at one end of said conduits to direct fluid flowing in one of the conduits to the other. At the opposite end, the conduits are connectable to a source of heat exchange fluid.  
         [0010]     In a further aspect, the present invention provides a heat distribution system having a source of heat exchange fluid, a manifold having a fluid supply and a fluid return, a pump to circulate fluid between the supply and return through the heat exchange fluid source and a conduit connected to each of the supplies and returns with said conduits being connected in series. The conduits transfer heat along their path. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     These and other features of the preferred embodiments of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein:  
         [0012]      FIG. 1  is a schematic representation of a heat distribution system.  
         [0013]      FIG. 2  is a perspective view of a heat distribution apparatus used in the system of  FIG. 1 .  
         [0014]      FIG. 3  is a view on the line III of  FIG. 2 .  
         [0015]      FIG. 4  is a view partly in section of an alternative embodiment of heating apparatus used in the system of  FIG. 1 .  
         [0016]      FIG. 5  is a view on the line V-V of  FIG. 4 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]     Referring therefore to  FIG. 1 , a heat distribution system  10  includes a fluid heater  12 , a central manifold  14  and a pair of heat distribution apparatus  16 ,  18  connected at respective locations to the manifold  14 . It will be appreciated that a cooling effect can be obtained using a fluid cooler rather than a heater but for ease of description reference will be made to the apparatus functioning as a heater.  
         [0018]     The fluid heater  12  is connected to the manifold  14  through a supply line  20  and a return line  22 . The lines  20 ,  22  are connected through an inlet  21  and outlet  23  to a coil  24  within the heater  12 . A heating source, such as a gas or electric heater, is supplied to the coil  24  so that fluid within the coil  24  is heated as it passes through the coil between the inlet  21  and outlet  23 . Fluid is circulated through the coil  24  by a pump  26  located within the manifold  24  and connected to the supply line  20 . The lines  20 ,  22  are connected to each of a series of outlets  30 ,  32 ,  34  provided on the manifold  14 . Each of the outlets  30 ,  32 ,  34  has a pair of pipes  36 ,  38 , one of which is connected to the supply line  20  and the other of which is connected to the return line  22 . The pipe  36  is connected to the supply line  20  through a check valve  40  and the return line  22  is connected to the pipe  38  through a selector valve  42 . The valve  42  may be moved between an open and closed position to permit fluid to flow from the pump  26  through the coil  24  to be discharged in the supply conduit  22  and to the outlet  30 . The manifold therefore permits selective distribution of fluid to one or more of the outlets  30 ,  32 ,  34 .  
         [0019]     The heat distribution apparatus  16  is connected to the outlet  30  and is shown in greater detail in  FIG. 2 . The apparatus  16  includes a conduit  50  having a peripheral wall  52  defining an interior channel  54  through which a fluid to be heated, for example water, flows. A pair of capillary tubes  56 ,  58  are located on the exterior of the peripheral wall  52  and extend axially parallel to the axis of the conduit  50 . A metallic tape  60  is interposed between the capillary tubes and the wall  52  and an outer sleeve  62  is located over the conduit  50 . The sleeve  62  is preferably made from heat shrinkable plastics material and retains the capillary tubes  56 ,  58  in location. A tracer wire  64  extends parallel to the capillary tubes  56 ,  58  to assist in locating the apparatus  16  at a later date if it is buried or hidden.  
         [0020]     At one end of the conduit  52 , the capillary tubes  56 ,  58  are interconnected by a connector  66 . The connector  66  is a press fit on the exterior of the capillary tubes  56 ,  58  and may be secured by a suitable cement. The connector  66  also includes a wire loop  68  that may be used to indicate the end of the capillaries during a subsequent inspection.  
         [0021]     The opposite end of the capillaries  56 ,  58  are split from the conduit  52  and connected at the port  30  to the lines  36 ,  38  respectively. A continuous loop is therefore provided from the pump  26  through the heater  12  and the capillaries  56 ,  58  for fluid that is heated within the coil  24 . The conduit  52  is used to convey fluid, such as a water supply line and the heat supplied from fluid flowing through the capillaries  56 ,  58  flows through the wall  52  to maintain the fluid above the freezing point or other predetermined temperature. The supply of heat may be regulated by varying the temperature of the fluid or by varying the flow rate through modulation of the pump  26 .  
         [0022]     An alternative heat distribution apparatus  18  is shown in greater detail in  FIGS. 4 and 5  and is intended for the direct application of heat to remote areas such as an eavestrough or roof or to be located internally within a fluid conduit, such as a water pipeline sewer. The heat distribution apparatus  18  includes a pair of concentric ducts  70 ,  72  defined by annular walls  71 , 73  respectively with an end-cap  76  bridging the termination of the ducts  70 ,  72 . At the opposite end, an end-cap  78  provides a spigot  80  for connection to the line  36 . The conduit  70  extends through the end-cap  78  where it is sealed by an o-ring  82  and terminates in an end-cap  84  with a connecting spigot  86  for connection to the line  38 .  
         [0023]     Again, therefore, the heated fluid is discharged through the spigot  86  into the duct  70  and is re-directed by end-cap  76  into the exterior duct  72 . Heat is transferred across the wall of the duct  72  to provide distributed heating to the surrounding environment.  
         [0024]     Each of the heat distribution apparatus  16 ,  18  has one or more temperature sensors  80 ,  82 , along the axis to sense either the temperature of fluid in conduit  52  or the ambient temperature. The sensor  80 ,  82  control the valves  42  to direct fluid to the outlet at which heat is required.  
         [0025]     The heating apparatus  16  may be co-extruded as a unitary moulding and sized to meet the requirements of the fluid within the conduit  52 . The heating apparatus  18  is likewise sized to provide a flexible pliant heater that may be entrained along the edge of a roof or within an eavestrough.  
         [0026]     Typically the fluid conduit is a extruded polyethylene pipe or similar extrudeable material. A cross linked polyethylene pipe, such as that known by the trade name PEX or KITEC is suitable. For a conduit of nominal 50 mm diameter the capillary tubes  56 ,  58  have a diameter of 5 mm to 10 mm for the apparatus  18 , the ducts  70 ,  72  have a diameter of 12 mm to 16 mm, although it will be appreciated that other dimensions may be used to suit different applications.  
         [0027]     In the embodiment of  FIGS. 2 and 3 , the number of capillary tubes  56 ,  58  may be increased to 4, 6, or more if required to meet the heating needs for particular environments. The pair of capillary tubes  56 , 58  may then be connected in parallel and supplied through a common manifold or may be controlled independently so that the heating effect can be regulated according to the ambient temperature. Thus, as the temperature drops below a given level, an additional pair of capillaries are connected to the heat source and additional heat supplied to the conduit by multiple flow paths.  
         [0028]     It will also be appreciated that the capillaries may be wound about the exterior of the conduit in a spiral pattern if so desired to distribute the heating effect uniformly over the wall  52  of the conduit.  
         [0029]     The capillaries may be co-extruded with the conduit  50  and may be secured with adhesive if preferred.  
         [0030]     Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto.