Abstract:
A modular insulated water tank comprising a hollow insulated support structure, a liner, and an insulated cover, with the support structure being comprised of two or more separable, vertically stackable retention tiers, the liner being a flexible container capable of retaining fluids within the interior of the support structure, and the cover being capable of enclosing contents contained within the interior of the water tank. So configured, the modular insulated water tank is capable of retaining a large quantity of fluid, such as water, at an elevated temperature for an extended length of time, for purposes of using the heat energy stored therein for space heating purposes or for domestic hot water use. The modular water tank employs a heating exchange interface comprised of inflow and outflow conduits and a heat exchanger, capable of bringing fluids into and out of the water tank to either release heat energy into the fluid contained in the water tank for heat storage or to absorb heat energy from the fluid contained in the water tank for heat use. The modular design of the water tank allows it to be easily shipped and stored, and assembled in otherwise difficult to access locations. The water tank is intended to be used to store heat energy generated by an external heat source, such as a boiler, solar collectors, or a wood stove.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to environmental climate control devices, namely, heat energy storage devices. Specifically, an aspect of the present invention relates to an improvement on water storage tanks for storing heat energy for residential and commercial use, where the heat energy is produced asynchronously by boilers, solar collectors, wood stoves, and the like. Improvements disclosed in the present invention include a modular configuration of the water tank to allow for easy manufacture, shipping, and storage, as well as easy assembly and disassembly in difficult to access locations. 
       BACKGROUND 
       [0002]    Water may be used as a storage medium for heat. In residential and commercial settings, this may be accomplished by use of a water storage tank. The tank is filled with water and then heat energy from an external source, such as solar collectors, geothermal heating, biomass, wood pellets, cogeneration, or even traditional fossil fuels or electrical sources, is used to raise the temperature of the water in the tank. The heat energy stored in the water may then be extracted for use in space heating or for domestic hot water purposes, or the heated water itself may be used for these purposes. Because water is capable of absorbing and retaining a great amount of heat energy, it is a cost-effect medium for storing heat energy that is collected or generated at a time other than when it is to be used. 
         [0003]    Typically, water storage tanks are constructed of steel and are lined with glass or concrete or some other massive material which insulates and helps retain heat. The tanks are also often wrapped in bulky insulation. However, this method of tank construction creates heavy and cumbersome tanks that are difficult to install. For example, the basement of a home or building is often the desired location for a water storage tank, but access to a basement is usually through a narrow staircase or small window. Therefore, traditional water storage tanks were usually limited in size, reducing the amount of heat energy that could be stored and eliminating efficiencies. In order to use make use of larger quantities of water to store heat energy (say, over 100 gallons), either multiple small tanks were necessary or large tanks were built on site, at substantial cost. 
         [0004]    There have been attempts to solve the problem of bringing large tanks into difficult to access locations. For example, U.S. Pat. No. 4,660,594 (Apr. 28, 1987), to Gocze, discloses a portable collapsible tank for storing and insulating heated water, in which the tank is comprised of an elongate flexible and foldable outer cylindrical sleeve formed with sufficient tensile strength to support the tank and water stored therein. These tanks could store up to 1500 gallons and were relatively easy to install, though time consuming. However, the water storage tanks of the &#39;594 patent are not structurally rigid, thereby leading to some inherent disadvantages, primarily that they are not designed to bear a load on their covers. Thus, persons climbing onto or placing objects on top of these tanks could inadvertently cause failure. Moreover, the substantially circular footprint of these tanks is an inefficient use of floor space. 
         [0005]    There thus remains a need for a water storage tank that is easy to manufacture, ship, and store, while providing the capability of storing a large quantity of water for long term retention of heat energy for later uses, which is also quick and easy to assemble in any location, is significantly stronger than previously patented tank designs, has a more efficient square configuration to better fit into buildings, and is structurally rigid to provide a greater margin of safety during use. 
         [0006]    It is therefore an object of an aspect of the invention to provide an improved modular insulated water tank which is easy to manufacture, ship, and store. 
         [0007]    It is a further object of an aspect of the invention to provide an improved modular insulated water tank which is easy to assemble and disassemble for use in difficult to access locations. 
         [0008]    It is yet a further object of an aspect of the invention to provide an improved modular insulated water tank capable of storing a large quantity of water for long term retention of heat energy for later uses. 
         [0009]    It is yet a further object of an aspect of the invention to provide an improved modular insulated water tank that is structurally rigid and capable of bearing external weight without failure. 
         [0010]    It is yet a further object of an aspect of the invention to provide an improved modular insulated water tank that utilizes an efficient footprint to better fit within a structure. 
         [0011]    It is yet a further object of an aspect of the invention to provide an improved modular insulated water tank which may be easily integrated with an external heating source, such as a boiler, solar collectors, a wood stove, a geothermal heating system, a biomass heating system, cogeneration, a fossil fuel burner, or electrical heat source. 
         [0012]    It is yet a further object of an aspect of the invention to provide an improved modular insulated water tank which efficiently integrates with a space heating system or a domestic hot water system. 
         [0013]    It is yet a further object of an aspect of the invention to provide an improved modular insulated water tank which can be easily reconfigured to contain greater or lesser quantities of water for heat energy storage purposes, as needed. 
         [0014]    Other objects of this invention will be apparent to those skilled in the art from the description and claims which follow. 
       SUMMARY OF THE INVENTION 
       [0015]    An aspect of the present invention discloses a modular insulated water tank useful for storing heat energy generated by an external heat source, such as a boiler, solar collectors, or a wood stove, which typically produces heat at a time when heat may not be called for. The modular configuration of the water tank allows it to be easily manufactured, shipped, and stored, and easily assembled in otherwise difficult to access locations, such as basements. The insulating properties of the water tank permit it to retain a large quantity of fluid, such as water, at an elevated temperature for an extended length of time, whereby the stored heat energy is made available for space heating purposes or domestic hot water use as required. 
         [0016]    The modular water tank is comprised of a hollow insulated support structure, a liner, and an insulated cover. The support structure is comprised of two or more separable, vertically stackable retention tiers. The liner is a flexible container capable of retaining fluids within the interior of the support structure, and the cover encloses the contents of the water tank. A heating exchange interface comprised of inflow and outflow conduits and a heat exchanger, capable of bringing fluid into and out of the water tank for purposes of either releasing heat energy or absorbing heat energy, is contained within the support structure and integrated with the external heat source and the external heating system or domestic hot water system. 
         [0017]    The retention tiers are fashioned of modular side walls and then stacked onto each other to form the support structure. The side walls of each retention tier may be removably joined to each other for easy assembly and disassembly. Reinforcement members may be employed to increase the rigidity of the side walls. 
         [0018]    Other features and advantages of the invention are described below. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0019]      FIG. 1  is a front perspective view of one aspect of the present invention, representing an embodiment having three retention tiers, each retention tier having four sides, and a cover comprising sub-covers. 
           [0020]      FIG. 2  is the same view depicted in  FIG. 1  except with the cover removed, thereby revealing the interior of the device in which the liner and the heating system interface are located. 
           [0021]      FIG. 3  is a perspective view of a single retention tier. In the depicted embodiment the retention tier is four sided and utilizes top and bottom reinforcement members. 
           [0022]      FIG. 4  is a top plan view of a retention tier. In the depicted embodiment each side wall of the retention tier has attached to its interior surface a flat metal panel, and onto each flat metal panel a flat insulating foam panel. No reinforcement members are shown. 
           [0023]      FIG. 5  is a perspective view of the detail of a corner of a retention tier. In the embodiment depicted each side wall of the retention tier has attached to its interior surface a flat metal panel, and onto each flat metal panel a flat insulating foam panel. The top and bottom reinforcement members of one side wall extend beyond the second lateral end of the side wall, thereby providing attachment points for the second side wall. Arrows show how the second side wall is positioned against the first side wall to form the corner. 
           [0024]      FIG. 6  is a an exploded perspective view of one aspect of the present invention, whereby the depicted embodiment has three retention tiers with each retention tier having four sides, a cover comprising three sub-covers, and a floor. 
           [0025]      FIG. 7  is a front perspective exploded view of a side of one embodiment of the present invention. Each of the side walls of the three retention tiers uses top and bottom reinforcement members, and the side is fitted with corner members. 
           [0026]      FIG. 8  is a perspective view of one embodiment of the heating system interface shown in  FIG. 2 , comprising a fluid inflow conduit, a fluid outflow conduit, and a heat exchanger formed of a plurality of coiled copper tubing tied together by an inflow manifold. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    An aspect of the present invention discloses a modular insulated water tank  1  capable of storing thermally isolated fluid. The water tank  1  comprises a support structure  100 , a liner  200 , and a cover  300 . See  FIGS. 1 and 2 . The support structure  100  is a substantially hollow enclosure formed of a plurality of substantially rigid sides  102  surrounding an interior  104 . It must be capable of containing and supporting the liner  200  within its interior  104  when the liner  200  contains fluid. Moreover, the sides  102  of the support structure  100  must be thermally isolatable, to minimize the loss of heat energy from the fluid contained within the water tank  1 . The support structure  100  is further comprised of two or more separable, stackable retention tiers  110 . See  FIG. 3 . Because the retention tiers  110  are separable, the support structure  100  may be broken down for ease of shipment and storage. 
         [0028]    The liner  200  is a flexible container capable of retaining fluids. In the preferred embodiment the liner  200  is a large, water-impermeable bag with an opening oriented upwards. The liner  200  should be dimensioned to fit within and substantially fill the interior  104  of the support structure  100 . When filled with a fluid, preferably water, the liner  200  is supported by the support structure  100 . The liner  200  may be constructed of polyethylene, polypropylene, polyvinyl chloride (PVC), ethylene propylene diene monomer rubber (EPDM rubber), or any other flexible, sturdy, water-impermeable material. In the preferred embodiment the liner  200  is constructed of 30 mil high temperature PVC. 
         [0029]    The cover  300  of the water tank  1  is suitably adapted to enclose the contents contained within the liner  200  within the interior  104  of the support structure  100 . The cover  300  must be thermally isolatable to minimize the loss of heat energy from the fluid contained within the water tank  1 . In one embodiment the cover  300  is constructed of the same material as comprises the rigid sides  102  of the support structure  100 . In another embodiment the cover  300  is comprised of two or more sub-covers  310  which fit together to form a single cover  300 . See  FIG. 1 . The use of sub-covers  310  allows for easier shipping and storage of the water tank  1 . It also allows for a subset of the sub-covers  310  to be fixedly attached to the support structure  100 , for security, with others being removable from the support structure  100  to permit access to the interior  104  of the support structure  100 . Caulk may be used to further seal the cover  300  or one or more of the sub-covers  310 . In other embodiments the cover  300  or one or more of the sub-covers  310  may be hingedly attached to the support structure  100 . 
         [0030]    Each of the retention tiers  110  comprising the support structure  100  has three or more substantially rigid, substantially planar side walls  120 . In the preferred embodiment each of the retention tiers  110  has four side walls  120 , forming a substantially rectangular continuous circumferential enclosure, open at the top and bottom. See  FIG. 3 . In other configurations each retention tier  110  may comprise six side walls to form a hexagon, or eight side walls to form an octagon, or any other number of side walls to form any preferred shape. Each retention tier  110  must have the same number of side walls  120  as each other retention tier  110 . See  FIG. 6 . The side walls  120  of each retention tier  110  should be substantially the same shape and size and arranged in substantially the same configuration as the side walls  120  of each other retention tier  110 . So configured, the retention tiers  110  are stacked vertically one on top of another, thereby forming the sides  102  of the support structure  100 . See  FIGS. 1 and 7 . 
         [0031]    Each of the individual side walls  120  of each retention tier  110  should be substantially rectangular. Pairs of adjacent side walls  120  are removably joined to each other at their respective adjacent lateral ends  121 , 122  such that the side walls  120  form a continuous circumferential enclosure. See  FIG. 4 . The adjacent pairs of side walls  120  are removably attached to each other at their junctions, to facilitate storage and shipping. See  FIG. 5 . All of the side walls  120  of each retention tier  110  should be of substantially uniform height, such that the top and bottom sides of each retention tier  110  are substantially parallel to each other and oriented substantially horizontally. 
         [0032]    The side walls  120  of the retention tiers  110  may be constructed of any substantially rigid insulating material. In the preferred embodiment each of the side walls  120  of each retention tier  110  is constructed of a rigid foam material. Rigid foam panels are typically formed of polystyrene, polyisocyanurate (polyiso), and polyurethane, but may be formed of any other suitable material known in the art. Each of the side walls  120  of each retention tier  110  may further utilize one or more substantially rigid vertical reinforcement members  130 , each said vertical reinforcement member  130  being oriented substantially vertically and integrated within a side wall  120 . See  FIG. 5 . In one embodiment the vertical reinforcement members  130  are configured as angles, having two substantially planar flanges oriented substantially ninety degrees to each other. In the preferred embodiment the vertical reinforcement members  130  are made of aluminum. However, they may be made of other materials having suitable rigidity and strength. In the most preferred embodiment the vertical reinforcement members  130  are configured as channel iron or channel steel having a squared-off “U” profile, with a vertical reinforcement member  130  fitted over each lateral end of each rigid foam sub-panel. The vertical reinforcement members  130  may be affixed to the sub-panels by mechanical fasteners, or by an adhesive, or both. In a preferred embodiment the side walls  120  are comprised of a plurality of substantially rectangular rigid foam sub-panels, with one or more vertical reinforcement members  130  placed between pairs of adjacent sub-panels. 
         [0033]    In another embodiment each of the side walls  120  of each retention tier  110  further comprises a substantially rigid top reinforcement member  140  and a substantially rigid bottom reinforcement member  150 . See  FIG. 5 . Both horizontal reinforcement members  140 , 150  are oriented substantially horizontally, with the top reinforcement member  140  located along the top side  124  of the side wall  120  and the bottom reinforcement member  150  located along the bottom side  125  of the side wall  120 . See  FIG. 7 . In one embodiment the horizontal reinforcement members  140 , 150  are configured as angles, having two substantially planar flanges oriented substantially ninety degrees to each other. In the preferred embodiment the horizontal reinforcement members  140 , 150  are made of aluminum. However, they may be made of other materials having suitable rigidity and strength. In the most preferred embodiment the horizontal reinforcement members  140 , 150  are configured as channel iron or channel steel having a squared-off “U” profile, with the top reinforcement member  140  fitted over the top side  124  of the side wall  120  and the bottom reinforcement member  150  fitted over the bottom side  125  of the side wall  120 . The horizontal reinforcement members  140 , 150  may be affixed to the side walls  120  by mechanical fasteners, or by an adhesive, or both. In other embodiments portions of the ends of the horizontal reinforcement members  140 , 150  may extend beyond the ends  121 , 122  of the side walls  120  to provide interlocking flanges for securing pairs of side walls  120  to each other, by screws or other appropriate fasteners. 
         [0034]    The water tank  1  may further comprise corner members  180 , each corner member  180  being substantially the same height as the fully assembled support structure  100  and suitably adapted to be placed over the junction of a pair of adjacent sides  102  of the support structure  100 . See  FIGS. 1 and 7 . Each corner member  180  should be rigid, constructed of aluminum, steel, rigid plastic, or the like. Each corner member  180  should further have a left flange  182  and a right flange  184 , with the left flange  182  angled from the right flange  184  to the substantially same degree as the corresponding adjacent sides  102  are angled to each other. In the preferred embodiment, where the support structure  100  has four sides  102  and a substantially rectangular configuration there are four corner members  180 , and the left and right flanges  182 , 184  of each corner member  180  are angled substantially ninety degrees from each other. See  FIG. 7 . Each corner member  180  is placed onto a corner of the support structure  100  such that the left flange  182  of the corner member  180  is adjacent to and affixed to one of the sides  102  of the corresponding pair of adjacent sides  102  and the right flange  184  of the corner member  180  is adjacent to and affixed to the other side  102  of the corresponding pair of adjacent sides  102 . The corner members  180  may be affixed to the sides  102  by mechanical fasteners, or by an adhesive, or both. 
         [0035]    In yet another embodiment, each of the side walls  120  of each of the retention tiers  110  has one or more flat metal panels  160  affixed to its inner surface  127 . See  FIGS. 4 and 5 . These panels  160  may cover substantially the entire inner surface  127  of each side wall  120 . The metal panels  160  add further rigidity to the retention tiers  110 . The metal panels  160  may be affixed to the inner surfaces  127  of the side walls  120  by mechanical fasteners, or by an adhesive, or both. In yet another embodiment one or more flat insulating foam panels  170  may be affixed to the metal panels  160 . See  FIGS. 4 and 5 . The foam panels  170  create a thermal break between the liner  200  and the metal components of the side wall  120 , thereby minimizing heat loss. 
         [0036]    In still another embodiment, each of the side walls  120  of each of the retention tiers  110  has one or more protective panels  190  affixed to its outer surface  128 . See  FIG. 7 . These panels  190  may cover substantially the entire outer surface  128  of each side wall  120 . The panels  190  add further rigidity to the retention tiers  110  and protect the retention tiers  110  from damage. The panels  190  may be made of metal, plastic, wood, or any other suitable material, and may be affixed to the outer surfaces  128  of the side walls  120  by mechanical fasteners, or by an adhesive, or both. 
         [0037]    The support structure  100  of the water tank  1  may be comprised of any number of vertically stacked retention tiers  110 . In the preferred embodiment the support structure  100  is comprised of three retention tiers  110 . See  FIGS. 1 and 7 . In the most preferred embodiment the lowermost retention tier  110  has a height shorter than the heights of the other two retention tiers  110 . This provides the lowermost retention tier  110  with a superior load bearing capability. In other embodiments gussets are used to help distribute the load of the fluid contained within the water tank  1 . In yet other embodiments wherein the water tank  1  is designed to contain a relatively large amount of fluid (in excess of 1000 gallons) strapping may be utilized circumferentially about the lowermost retention tier  110  to further resist the potential for buckling of the side walls  120  of that retention tier  110 . 
         [0038]    In another embodiment of the water tank  1 , a floor  400  is used. See  FIG. 6 . In this embodiment the floor  400  is placed beneath and attached to the bottom of the support structure  100 , forming a lowermost portion of the water tank  1 . The floor  400  is substantially planar, so that a large proportion of its lower surface area is in contact with the surface upon which it is placed. The floor  400  should also be thermally isolatable, to minimize heat loss from the fluid contained within the water tank  1 . In another embodiment the floor  400  is constructed of the same material as comprises the rigid sides  102  of the support structure  100 . 
         [0039]    The water tank  1  may include a heating system interface  500  which is used to transfer heat energy into and out of the water tank  1 . See  FIG. 2 . The heating system interface  500  may be comprised of a fluid inflow conduit  510 , a fluid outflow conduit  520 , and a heat exchanger  530 . See  FIG. 8 . The fluid inflow conduit  510  must be capable of transporting a first fluid from a location exterior to the water tank  1  into the interior of the water tank  1 . The fluid outflow conduit  520  must be capable of transporting the first fluid from within the interior of the water tank  1  to a location exterior to the water tank  1 . The heat exchanger  530  must be capable of transferring heat energy between the first fluid and a second fluid that is retained within the of the water tank  1 . The fluid inflow conduit  510 , the heat exchanger  530 , and the fluid outflow conduit  520  are placed in respective serial fluid communications with one another to circulate the first fluid into and out of the water tank  1 . In one embodiment the fluid inflow conduit  510  and the fluid outflow conduit  520  are comprised of copper tubing. However, other materials are also contemplated. 
         [0040]    In a typical configuration, the water tank  1  will be used in both heat storage mode and in heat usage mode. In heat storage mode, the first fluid will preferably be water, which will receive heat energy from an external heat source, such as a boiler, solar collectors, a wood stove, or the like. The second fluid will also preferably be water, retained within the water tank  1 . The water heated from the external heat source will flow into the water tank  1  via the inflow conduit  510 , give up heat energy to the water contained within the water tank  1  via the heat exchanger  530 , and then flow out of the water tank  1  via the fluid outflow conduit  520 . The first fluid may be circulated by use of a circulating pump. In this mode, the second fluid absorbs and retains heat energy from the first fluid for future use. In heat usage mode, the first fluid will have a lower temperature than the second fluid; this colder water will flow into the water tank  1  via the fluid inflow conduit  510 , absorb heat energy from the water contained within the water tank  1  via the heat exchanger  530 , and then flow out of the water tank  1  via the fluid outflow conduit  520  to an external heating system or domestic hot water system. The first fluid may be circulated by use of a circulating pump. 
         [0041]    The heat exchanger  530  may be any type of heat exchanger known in the art that permits the exchange of heat energy between the first and second fluids. In the preferred embodiment the heat exchanger  530  will be located within the interior  104  of the support structure  100  inside the liner  200  and will be submerged within the second fluid. See  FIG. 2 , In one embodiment the heat exchanger  530  may be comprised of a plurality of coiled copper tubing  532 , each said coil  532  attached in parallel to an inflow manifold  534 . See  FIG. 8 . Each of the coiled copper tubing  532  should have a relatively small inside diameter, to increase the surface-to-volume ratio of the tubing  532  as well as to increase the amount of turbulence of the first fluid when it passes through the tubing  532 , thereby accelerating the exchange of heat energy. In the most preferred embodiment the inside diameter of the coiled copper tubing  532  is between ⅜ inches and ⅝ inches. In this embodiment a sufficient number of parallel copper tubes  532  are used to minimize back pressure on the inflow of the first fluid via the fluid inflow conduit  510 . The preferred number of parallel copper tubes  532  is between two and nine. 
         [0042]    While many different configurations of the present invention are possible, in the most preferred embodiment the support structure  100  will be comprised of three stacked retention tiers  110 , each retention tier  110  comprised of four side walls  120  in a substantially rectangular configuration, with the side walls  120  of each retention tier  110  comprised of rigid foam and incorporating both vertical and horizontal reinforcement members  130 , 140 , 150  and interior metal and foam panels  160 , 170 , with the support structure  100  having four corner members  180  and a floor  400 , the cover  300  being comprised of two sub-covers  310 , and the water tank  1  having a fluid inflow conduit  510 , fluid outflow conduit  520 , and heat exchanger  530  all comprised of copper tubing. The water tank  1  may be manufactured and shipped as disassembled components, for ease of shipment as well as ease of placing the water tank  1  in its proper location, for example in a basement with difficult access. For installation, the side walls  120  are assembled into the retention tiers  110 ; the lowermost retention tier  110  is placed onto and attached to the floor  400  and the remaining retention tiers  110  are stacked onto each other; the corner members  180  are fastened to the corners of the support structure  100 ; the liner  200  is placed within the support structure  100 ; the fluid inflow conduit  510 , fluid outflow conduit  520 , and heat exchanger  530  are properly placed within the water tank  1 ; and the cover  300  is placed over the top of the support structure  100 . The fluid inflow and outflow conduits  510 , 520  are plumbed and then the liner  200  is filled with water to ready the water tank  1  for use. 
         [0043]    What has been described and illustrated herein is a preferred embodiment of the invention along with some it its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention as defined in the following claims in which all terms are meant in their broadest, reasonable sense unless otherwise indicated.