Abstract:
The present invention is a system for managing heat stress by both controlling the core body temperature of an individual and facilitating hydration. The system provides cooling to an individual through means of a liquid coolant such as water which is circulated by a pump through a heat exchanger to a heat exchange garment. The liquid coolant passes through the heat exchange garment where it extracts heat, increasing in temperature as a result of heat removed from the individual wearing the garment. The liquid coolant is then returned to the heat exchanger where it is again cooled. The cycle is then repeated. A drinking outlet provides a means for hydrating the wearer.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a heat exchanging apparatus, and in particular to an apparatus for cooling the body of an individual in heat stress.  
         BACKGROUND OF THE INVENTION  
         [0002]    Certain occupations are known to expose individuals to heat stress resulting from the use of protective clothing and/or exposure to harsh environmental conditions. Examples of these occupations include fire fighting, hazardous materials (HAZMAT) cleanup, brick-firing and ceramics operations, iron and steel foundry operations, laundry and dry cleaning, and explosive ordnance disposal (ROD). As well, athletes training or competing in the outdoors can be vulnerable to heat stress. Heat stress can result in illnesses such as heat cramps, fainting, heat exhaustion, heat stroke, and dehydration. All of these illnesses can have a major effect on both performance and safety.  
           [0003]    In order to prevent or decrease the effects of heat stress, a number of body cooling systems have been developed. The three kinds of body cooling systems that are most prominent are ice cooling systems, circulating air systems, and liquid cooling systems.  
           [0004]    Ice cooling systems usually consists of ice packets held in pockets in a garment such as a vest. These “ice vest” garments are designed to cool the torso due to the large surface area available for heat exchange. The ice vest garment is worn close to the skin and as such provides cooling to the wearer of the garment by conduction. Ice packets filled with water are generally used, although carbon dioxide (dry ice) can also be used. The cooling offered by the ice packets lasts only a limited number of hours depending on the intensity and frequency of the work performed by the wearer of the ice vest garment. Ice vests are heavy and require doffing to replenish the cooling medium. As well, they do not allow the user to control the rate of cooling. Another concern is that the very high temperature difference between ice (less than 0° C.) and the skin of the wearer of the garment may cause localized ‘freeze’ burns.  
           [0005]    An alternate means of body cooling is with circulating air systems. Such systems typically include a torso garment, a compressor, and an umbilical cord which carries pre-chilled air from the compressor to the garment. The pre-chilled air circulates around the body of the wearer under the garment, increasing the evaporation of sweat, and to a lesser extent provides cooling by convection, and then exits through cuffs or special vents. Cooling capacity can be enhanced with the use of compressed air and a vortex tube that reduces the air temperature supplied to the distribution system. An example of a circulating air system is U.S. Pat. No. 5,386,823 to Chen. Circulating air systems, however, are noisy and require a constant source of compressed air supplied through an attached air hose, thus limiting worker mobility. These systems can also lead to more rapid dehydration. While the cool, dry air supplied feels comfortable to the wearer of the garment, the wearer may not realize that hydration through frequent liquid ingestion is still required to minimize the adverse effects of heat stress.  
           [0006]    A third body cooling system that is available is known as a liquid cooling system. A liquid cooling system provides cooling of the skin through a steady flow of cool liquid through closed circuits of tubing in a suit. U.S. Pat. No. 4,691,762 to Elkins et al is exemplary of such a system. In such systems a chilled liquid, usually water, is circulated by a pump through a heat exchanger to a user wearable garment. The fluid passes through tubes in the garment where it extracts heat before returning to the heat exchanger where it is again cooled. The cycle is then repeated. Ice is typically used as the heat sink for the heat exchanger. Liquid cooling systems have the advantage of allowing significant wearer mobility and independence.  
           [0007]    Adequate fluid replacement can be at least as important as cooling when seeking to minimize the effects of heat stress. It is well understood that proper hydration through fluid ingestion helps maintain health, safety and an optimal physical performance. It is also known that without adequate fluid replacement, dehydration and even hyperthermia can occur. Water loss occurs during the evaporation of sweat from the surface of the skin, which acts to rid the body of excess heat. The effects of water loss are further enhanced by the intensity of the activity, the temperature, relative humidity, clothing, physical fitness and acclimatization of an individual. To prevent the occurrence of dehydration and heat-induced disorders, it is extremely important to maintain the necessary body fluid levels, which involves consuming water prior to, during and following an activity that takes place over a sustained amount of time.  
         SUMMARY OF THE INVENTION  
         [0008]    In accordance with an aspect of the present invention there is provided a portable personal cooling and hydration system comprising:  
           [0009]    a heat exchange garment incorporating a garment inlet, a garment outlet and a garment fluid path extending from the garment inlet to the garment outlet;  
           [0010]    a heat exchanger having an exchanger inlet, an exchanger outlet and a heat sink wherein the heat exchanger is adapted to receive a supply of fluid through the exchanger inlet and to emit cooled fluid from the exchanger outlet;  
           [0011]    a pump;  
           [0012]    a plurality of conduits interconnecting the garment fluid path, the heat exchanger and the pump in a circuit, the circuit being adapted to conduct a fluid in operation; and  
           [0013]    a reservoir containing a drinkable fluid, associated with the heat exchanger, and incorporating a drinking outlet;  
           [0014]    wherein the heat exchanger, the pump, the plurality of conduits and the reservoir are adapted to be carried by a user of the heat exchange garment.  
           [0015]    The present invention is a system for managing heat stress by both controlling the core body temperature of an individual and facilitating hydration. The system provides cooling to an individual through means of a liquid coolant such as water which is circulated by the pump through the heat exchanger to the heat exchange garment. The liquid coolant passes through the heat exchange garment where it extracts heat, increasing in temperature as a result of heat removed from the individual wearing the garment. The liquid coolant is then returned to the heat exchanger where it is again cooled. The cycle is then repeated. The drinking outlet provides a means for hydrating the wearer.  
           [0016]    In one embodiment, the system of the present invention is a self-contained portable unit worn by an individual. The portable unit comprises a backpack for housing the heat exchanger, the circulating pump, and the tubing necessary to carry liquid coolant between the heat exchanger and the heat exchange garment. The heat exchanger comprises a sealed, insulated bag containing copper tubing surrounded by a reservoir of liquid such as ice water. The pump circulates liquid coolant out of the heat exchanger and into a heat exchange garment which typically comprises a vest or pants containing a plurality of hollow tubes sewn into the garment. A drinking tube is connected to a drinking port in the bag so that the individual can hydrate himself/herself. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    In figures which illustrate, by way of example only, embodiments of the present invention,  
         [0018]    [0018]FIG. 1 is a schematic plan view of a heat exchanger in accordance with the present invention;  
         [0019]    [0019]FIG. 2 is a schematic plan view of the cooling loop of the present invention;  
         [0020]    [0020]FIG. 3 is a schematic front view of the inside of a typical heat exchange garment that can be used in association with the present invention;  
         [0021]    [0021]FIG. 4 is a perspective view an embodiment of the present invention contained in a backpack;  
         [0022]    [0022]FIG. 5 is a perspective view of the backpack of FIG. 4 shown carried on the back of a wearer; and  
         [0023]    [0023]FIG. 6 is a perspective view of the wearer of FIG. 5 ingesting fluids from the backpack of FIG. 4. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    [0024]FIG. 1 shows a heat exchanger  2  which is a component of a cooling loop  18  depicted in FIG. 2. In brief, a circulating cooling fluid passes through cooling loop  18  and a heat exchange garment  80  shown in FIG. 3. As this fluid passes through the heat exchange garment it absorbs heat, cooling the individual wearing the garment. After the circulating cooling fluid leaves the heat exchange garment, it is pumped through heat exchanger  2 , which transfers the heat from the circulating cooling fluid to a heat sink. The cycle then repeats itself until switched off.  
         [0025]    Heat exchanger  2  is defined by a watertight reservoir  4 . The reservoir  4  is preferably made of a lightweight flexible material such as treated nylon or a heavy plastic. A screw cap  6  is located at an upper end of the reservoir  4 . Screw cap  6  is mated with a hole (not shown) in reservoir  4 . When in place, screw cap  6  forms a watertight seal with reservoir  4 .  
         [0026]    When screw cap  6  is removed, reservoir  4  is filled with a heat sink liquid  5  which is poured through the hole. Heat sink liquid  5  is preferably a mixture of ice and water, made up predominately of ice. Alternatively, other drinkable fluids (preferably in partially frozen state) may also be used.  
         [0027]    Reservoir  4  includes a drain valve  8  at its lower end. Drain valve  8 , as well as the various other tubes and connectors described herein, is preferably of a type known in the art and formed from PVC (polyvinyl chloride). Drain valve  8  is normally in a closed position. However, drain valve  8  is opened when reservoir  4  is emptied for cleaning or before heat sink liquid  5  is replenished.  
         [0028]    A copper tube  10  is positioned as shown within reservoir  4 . Although preferably made of copper, the copper tube  10  may be made of any similar highly heat conductive material known in the art. The copper tube  10  is a single continuous tube which describes a circuitous route within the reservoir  4 . The copper tube  10  is fixedly positioned within the reservoir  4  by an inlet connector  12  and an outlet connector  14  at opposite ends of the copper tube  10 . The connectors  12  and  14  extend through the reservoir  4  and seal an interior of the copper tube  10  from the reservoir  4  and seal the reservoir  4  from leakage. When the reservoir  4  is filled, the copper tube  10  is surrounded by the heat exchange fluid  5 .  
         [0029]    The reservoir  4  also has a connector  16  at a lower end. The connector  16  extends from the interior to an exterior of the reservoir  4 . The operation of the connector  16  will be explained further in reference to FIG. 2.  
         [0030]    [0030]FIG. 2 shows the heat exchanger  2  in the cooling loop  18 . The cooling loop  18  is a hydraulic circuit which contains a circulating cooling fluid. The circulating cooling fluid is preferably water but can alternatively be another heat exchange fluid known in the art such as antifreeze.  
         [0031]    The cooling loop  18  is primarily comprised of the heat exchanger  2 , a pump  40 , a replenishing reservoir  20 , a heat exchange garment (shown only in FIG. 3), and a series of interconnecting tube segments. The replenishing reservoir  20  is a small container, of plastic or other lightweight watertight material. The replenishing reservoir  20  is a known requirement of a hydraulic circuit needed to replenish losses of the circulating cooling fluid.  
         [0032]    A cap  28  seals the replenishing reservoir  20 . An inlet hole  24  and an outlet hole  22  are defined through the cap  28 . A first end of a tube segment  30  extends through the outlet hole  22  and a first end of a tube segment  90  extends through the inlet hole  24 . The tube segment  30  and the tube segment  90  are sealed to the respective holes  22  and  24 . It is understood that all the tubing interconnections described herein form watertight seals. A filter  26  covers the first end of the tube segment  30 . The filter  26  is of a type known in the art. The filter  26  allows the circulating cooling fluid to enter the tube segment  30  while blocking dirt or other debris.  
         [0033]    A second end of the tube segment  30  is interconnected to a fluid inlet of the pump  40 . The pump  40  is a positive displacement pump, preferably a gear pump or diaphragm pump. The pump  40  is powered by a battery pack  56  and controlled by an on/off controller  52 . The battery pack  56  preferably consists of 4 D-cell batteries but rechargeable or other battery combinations may be used. The pump  40 , the battery pack  56  and the on/off controller  52  are interconnected in an electrical circuit  60  by a series of electrical wires  42 . A fuse  58  forms part of an electrical interconnection between the battery pack  56  and the pump  40  to protect the pump  40  from overload.  
         [0034]    The on/off controller  52  has an on/off switch  46  and, optionally, an LED (light emitting diode)  50  or other known indicator. The LED  50  is connected to the electrical circuit  60  through a resistor  48 . The on/off switch  46  is of a push button type. In operation, the LED  50  is lighted when the pump  40  is turned on. An electrical connector  54  allows the battery pack  56  to be disconnected from the electrical circuit  60  and an electrical connector  44  similarly allows the on/off controller  52  to be disconnect from the electrical circuit  60 .  
         [0035]    A fluid outlet of the pump  40  is interconnected to a T-junction  68  by a tube segment  66 . A first outlet of the T-junction  68  is interconnected to an inlet of a relief valve  41  by a tube segment  62 . The relief valve  41  is of a type known in the art. The relief valve  41  is normally in a closed position such that no circulating cooling fluid is flowing through the tube segment  62 . A second outlet of the T-junction  68  is interconnected to the inlet connector  12  of the heat exchanger  2  by a tube segment  74 . The outlet connector  14  of the heat exchanger  2  is in turn interconnected to a quick disconnect valve  78  by a tube segment  76 .  
         [0036]    The quick disconnect valve  78  connects to a heat exchange garment  80  (shown is FIG. 3). The quick disconnect valve  78  has an outlet  84  to the heat exchange garment  80  and a return  82  from the heat exchange garment. The return  82  is further connected to a tube segment  38 . A second end of the tube segment  38  is coupled to a T-junction  34 . A second inlet of the T-junction  34  is connected to a tube segment  36 . The tube segment  36  interconnects the T-junction  34  to an outlet of the relief valve  41 . As previously indicated, the relief valve  41  is normally in an closed position such that no circulating cooling fluid is flowing through the tube segment  36  and the relief valve  41 .  
         [0037]    As noted in regard to FIG. 1, the heat exchanger  2  has a connector  16  at a lower end. The connector  1 - 6  is interconnected to a bite valve  94  by a tube segment  92 . The bite valve  94  is of a type known in the art. The bite valve  94  is normally closed and is opened when a user squeezes the bite valve  94  between their teeth. When the bite valve  94  is opened, the user draws in water as with any drinking straw. The connector  16  in normally open and the heat sink liquid  5  from the reservoir  4  flows freely into tube element  92 . The bite valve  94  provides a seal to the reservoir  4  to prevent fluid from escaping through connector  16  and the tube segment  92 . The connector  16  is shown to be connected to the reservoir  4  of the exchanger  2 . However, alternatively, the connector  16  could connect to a separate reservoir.  
         [0038]    In operation, the reservoir  4  is first filled with the heat sink liquid  5 . Similarly, the cooling loop  18  is also filled with the circulating cooling fluid. The pump  40  provides hydraulic power to the cooling loop  18 . The operation of the heat exchange circuit will be described beginning with the replenishing reservoir  20 . The circulating cooling fluid exits the replenishing reservoir  20  through the filter  26  and the tube segment  30 . The circulating cooling fluid flows out through the outlet hole  22  and the tube segment  30 .  
         [0039]    The circulating cooling fluid flowing through the tube segment  30  will enter the pump  40  and be forced forward by the pump  40  through the tube segment  66 . The cooling fluid will flow from the tube segment  66  through the T-junction  68  to the tube segment  74 . The relief valve  41  is normally in the closed position so that no fluid flows through the tube segments  36  and  62 . The circulating cooling fluid will then flow into the inlet connector  12  to the copper tube  10  within the heat exchanger  2 . The copper tube  10  is, as noted above, surrounded by heat sink liquid  5 , which comprises a mixture of water and ice. The circulating cooling fluid flowing through the copper tube  10  will be cooled by the conduction of heat from the circulating cooling liquid through the copper tube  10  to the heat sink liquid  5  in the reservoir  4  of the heat exchanger  2 . The circuitous route of the copper tube  10  through the reservoir  4  is intended to optimize the length of time the circulating cooling fluid, at a given rate, is exposed to the heat sink liquid  5  in the reservoir  4  to facilitate maximum cooling. The circulating cooling fluid flows out through the outlet connector  14  to the tube segment  76 .  
         [0040]    In operation, the quick disconnect valve  78  is connected to the heat exchange garment  80 . The now chilled circulating cooling fluid flows through the outlet  84  and into the heat exchange garment  80  (FIG. 3). The flow of the circulating cooling fluid through the heat exchange garment  80  cools the wearer as described in respect of FIG. 3. The circulating cooling fluid then returns through the return  82  of the quick disconnect valve  78 . The circulating cooling fluid returns in a heated state and flows through the tube segment  38 , through the T-junction  34 , through the tube segment  90  and back through the inlet hole  24  into the replenishing reservoir  20 . The cycle is repeated to again cool the circulating cooling fluid and in turn cool the wearer.  
         [0041]    The purpose of the relief valve  41  is to protect the pump  40  from damage if the quick disconnect  78  is disconnected from the heat exchange garment  80  while the pump remains running. If this happens, the pressure built by the pump  40  in the circuit will open the relief valve  41  forming an alternative fluid circuit which excludes the heat exchange garment  80  to prevent burn out of the pump  40 .  
         [0042]    The heat sink liquid  5  contained in the reservoir  4  is gradually warmed and the ice melted by the process of heat exchange with the circulating cooling fluid. As previously noted, the reservoir  4  is connected to the bite valve  94  via the connector  16  and the tube segment  92 . When the wearer of the heat exchange system requires hydration, the wearer need only bite on the bite valve and drink the heat sink liquid  5  from the reservoir  4  through the tubing  92 . Thus, the reservoir  4  serves a dual purpose. It both functions as the heat sink of the heat exchange system and functions as a fluid reservoir for the hydration of the wearer of the heat exchange garment  80 . As an added benefit, the consumption of the fluid portion of the heat sink liquid  5 , reduces the thermal load on the heat exchanger  2  since the fluid is the warm component of the ice and fluid mixture which comprises the heat sink liquid  5 .  
         [0043]    An exemplary heat exchange garment  80  is depicted in FIG. 3. The quick disconnect valve  78  is depicted schematically. As described above, the circulating cooling fluid flows out through the quick disconnect valve  78  and into a network of tubing  100  which extends through a heat exchange garment  80 , in this case, a shirt. When the shirt is worn, the flow of the circulating cooling fluid through the shirt provides a second heat exchange system. The circulating cooling fluid is gradually heated, and the wearer cooled, as the heat from the wearer&#39;s body is conducted to the circulating cooling fluid. The circulating cooling fluid exits the shirt in a heated condition and returns to the cooling loop  18  depicted in FIG. 2.  
         [0044]    [0044]FIG. 4 depicts the preferred physical embodiment of the heat exchange system of the present invention. The entirety of the system including the heat exchanger  2 , the pump  40 , the replenishing reservoir  20 , and all other components of the system are contained within a back pack  102 . The backpack  102  can be easily worn by the wearer of the heat exchange garment  80  as shown in FIG. 5. This arrangement makes the system completely portable. When the reservoir  4  has been depleted, the reservoir  4  can easily be refilled by opening the screw cap  6  and filling the reservoir  4 . As can be seen in FIG. 4, the tube segment  92  and the bite valve  94  preferably extend at shoulder level from the backpack. The tube segment  92  operates as a straw to allow the wearer to easily drink from the reservoir  4  as shown in FIG. 6. The backpack  102  is preferably constructed of lightweight insulating material to assist in maintaining the reservoir  4  at a low temperature.  
         [0045]    The above description of a preferred embodiment should not be interpreted in any limiting manner since variations and refinements can be made without departing from the spirit of the invention. The scope of the invention is defined by the appended claims and their equivalents.